• <tr id="yyy80"></tr>
  • <sup id="yyy80"></sup>
  • <tfoot id="yyy80"><noscript id="yyy80"></noscript></tfoot>
  • 99热精品在线国产_美女午夜性视频免费_国产精品国产高清国产av_av欧美777_自拍偷自拍亚洲精品老妇_亚洲熟女精品中文字幕_www日本黄色视频网_国产精品野战在线观看 ?

    Photoactivation experiment of 197Au(γ,n)performed with 9.17-MeV γ-ray from 13C(p,γ)14N?

    2019-11-06 00:43:40YongLeDang黨永樂FuLongLiu劉伏龍GuangYongFu付光永DiWu吳笛andNaiYanWang王乃彥
    Chinese Physics B 2019年10期
    關鍵詞:永樂

    Yong-Le Dang(黨永樂), Fu-Long Liu(劉伏龍), Guang-Yong Fu(付光永),Di Wu(吳笛), and Nai-Yan Wang(王乃彥),?

    1College of Nuclear Science and Technology,Beijing Normal University,Beijing 100875,China

    2China Institute of Atomic Energy,Beijing 102413,China

    Keywords:resonance reaction,high energy γ-ray,photonuclear reaction

    1.Introduction

    Development of nuclear power is the strategic choice for solving the energy supply and ensuring the sustainable development of economy and society.However,nuclear reactor of 1-GW power products about 30-tons spent fuel per year,including long-lived fission product(LLFP)about 30 kg.[1]In this situation,the disposal of LLFP becomes much important.The prime ways such as deeply bury,transport to the space,and ice cover are unable to ensure absolute safety which is the fundamental requirement of long-lived radioactive wastes disposal. In 1990s,Accelerator Driven Sub-critical System(ADS)was known as an effective method.[2]For most radioactive wastes,the neutron cross sections are high enough so the coupling efficiencies of transmutation are considerable.However,for some nuclei,the neutron cross section is very low and there may be some new radioactive nuclei generated during the transmutation of137Cs.Another approach,photoneutron transmutation,due to the giant dipole resonance(GDR),may be a supplement of neutron transmutation,in which the largest cross section will be several hundreds millibarn in the high energy range.[3]

    The high energy γ-ray is generated mainly by bremsstrahlung,positron annihilation in flight,laser Compton scattering,and nuclear excitation in nuclear reaction.[4]As a standard for studies on photonuclear reactions,197Au(γ,n)has been investigated to verify the ability of transmutation perform with γ-ray.In previous studies,photonuclear experiments were performed mainly by using the γ-ray source of positron annihilation in flight.[5]The photoactivation experiment on197Au was measured with bremsstrahlung facility on ELBE(electron linear accelerator of high brilliance and low emittance).[6]The photoneutron cross section of197Au(γ,n)was measured with laser Compton scattering γ-ray at ring at AIST Tsukuba.[7]The nuclear transmutation rate on197Au was measured on New SUBARU.[8]While the γ-rays from positron annihilation in flight,bremsstrahlung,and laser Compton scattering are not mono-energetic even continuous,so it is necessary to study the cross section or transmutation using mono-energetic γ-ray and compare the result with the measured values obtained with other methods.

    Table 1 shows several(p,γ)resonance reactions of light nuclei.In the present work,γ-ray from13C(p,γ)14N reaction at Ep=1.75 MeV has been used to measure the cross sections of197Au(γ,n)at 9.17 MeV,by measuring the γ-ray decay from the reaction product,196Au. For the accuracy of measurement,the depth distribution of196Au in gold target and the attenuation of γ-ray from196Au inside the target have been taken into account.

    Table 1.Several resonance reactions.

    2.Experiment

    According to the previous investigations,the reaction threshold of197Au(γ,n)and197Au(γ,2n)are 8.07 MeV and 14.7 MeV respectively.[9]So for the experiment of irradiation on197Au by 9.17-MeV γ-rays generated from13C(p,γ)14N reaction at Ep=1.75 MeV,only197Au(γ,n)reaction can be taken place. There are two methods in measuring this reaction rate,i.e.,by measuring neutrons during the reaction and by measuring γ-rays following the product.Considering the count rate of detector and the background during the irradiation,we decide to measure the γ-rays decay after the irradiation.

    As the product of197Au(γ,n)reaction,the unstable nucleus196Au will decay to196Pt(T1/2=6.18 d)by EC+β+or to196Hg by β?.Several main γ-rays during the decay of196Au and their emission probabilities are shown in Table 2.We can see,for the most part,196Au will decay to196Pt with the emission of 355.73-keV γ-rays which can be detected and used to determine the number of196Au nuclei.

    Table 2.Several γ-rays during the decay of 196Au and their emission probabilities.

    In previous experiment about13C(p,γ)14N at the 2×1.7-MV tandem accelerator in China Institute of Atomic Energy(CIAE),we had already determined the thick target yield and angular distribution of 9.17-MeV γ-ray.[10]The experimental setup of photoactivation experiment is shown in Fig.1.

    Fig.1.Experimental setup.

    Before the experiment,we should estimate the reaction rate for this experiment,so the thickness of gold target had to be chosen.Because of the attenuation of 355.73-keV γ-rays in the target,it makes no sense to set a very thick target.We estimated the activities after 1-hour irradiation,in which the yield of 9.17-MeV γ-rays was used 4.7×10?9γ/proton in 4π,and the proton beam was 8μA and the thicknesses of targets were changed from 0.05 cm to 2 cm.The estimation result is shown in Fig.2.The value of cross section of197Au(γ,n)we used in calculations is 50 mb.[9]In Fig.2,the activity is going to be saturated when the thickness reaches to 1 cm.However,there is also attenuation for decaying γ-rays in the target,so the thickness should be chosen as thin as possible. By considering those reasons,we finally chose the target thickness as 0.2 cm.

    Fig.2.Calculation of the activities of targets with different thicknesses after 1-hour irradiation.

    In the experiment,the 8-μA proton beam was directed onto an isotopically pure13C target with 100-μg/cm2thickness,which was evaporated on a gold disk in size φ10×2 mm and cooled with air. There was a collimation to make sure that protons should be bombarded at the center of the target.The coaxial HPGe detector(GXM35P4-70,Ortec)was placed at 69-cm distance from the target and positioned at 0?,it was used to monitor the yield of γ-rays in order to calculate the number of γ-rays which was irradiated on the197Au target.Two197Au targets had been irradiated for 6 h and 5.5 h respectively.To avoid the impact of decay from short-lived nuclei generated during the bombardment,the targets had been shelved for about 3 h.By a rough estimation,the count rate of 355.73-keV γ-rays will no more than 100-per hour. The number of γ-rays from activated nuclei produced during the activation was determined offline with a low-background and anti-Compton HPGe detector with 105%relative efficiency at CIAE.The full-energy background count rate of this detection system is about 0.1 per second.The γ-ray source133Ba was used to calibrate the absolute efficiency of low-background and anti-Compton HPGe detector system.

    There exists absorption when γ-rays traversing through the gold target. The attenuation must be taken into account when measuring the number of 9.17-MeV γ-rays. We set a LaBr3crystal detector in φ3×3 inch(1 inch=2.54 cm)at back direction of proton beam at 85-cm distance from the target and positioned at 125?. Before the irradiation,the13C target was evaporated on a thin Ta disk in order to normalizing these two detectors.By comparing the count rate of two detectors when the gold target was placed,the attenuation could be determined.It is not only necessary for measuring the number of γ-rays but also important for determining the total cross section of 9.17-MeV γ-rays in the gold target.

    3.Data analysis and result

    To gain the high statistics,two gold targets were irradiated by γ-rays for 21600 s and 19800 s,shelved for 12900 s and 11040 s respectively.We determine the cross section of197Au(γ,n)by measureing 355.73-keV γ-rays from the product of196Au.Figure 3 shows the spectrum of γ-rays emitted from196Au after irradiation of197Au.

    Fig.3. Spectrum of γ-rays emitted from 196Au after irradiation of 197Au using low-background and anti-Compton HPGe detector system for about 4 days.The 333.03-keV and 355.73-keV lines are marked which both decayed from 196Au.

    The absolute full-energy-peak detecting efficiency of HPGe detector for γ-ray of 355.73 keV was determined by measuring the 356.01-keV γ-ray decay from133Ba source with the radioactivity of 1.07×105Bq and the emission probability of 356.01-keV γ-ray is 0.621. Considering the emission probability of 355.73 keV from196Au,we got the detecting efficiency,ε=(2.379±0.003)×10?2.

    Our experimental setup is shown in Fig.4,the travelling distances are different when 9.17-MeV γ-rays injecting from different angles.

    Fig.4.Target setup.

    The total number of target nuclei in unit area Nsalong θ direction can be written as

    where h and r are the thickness and radius of the gold target,respectively,NAis the Avogadro constant,θ0=arctan(r/h).Thus the photoneutron reaction rate in ?? can be written as

    where I(θ)=I(θdet)W(θ)/W(θdet)is the flux of 9.17 MeV in unit solid angle at θ,in which θdetis degree where the detector was established,W(θ)is the angular distribution of 9.17-MeV γ-rays which has been measured in our previous work,[10]and σgis the photoneutron cross section,σtis the total absorption cross section.The term(1 ?e?Ns(θ)σg)is the probability of photoneutron reaction.By integrate Eq.(2),the photoneutron reaction rate can be written as

    Set t as the irradiated time,t1as the shelved time,t2as the detecting time.The number of196Au nuclei after t and number of196Au decay during t2will respectively be,

    Actually,the absorption of 355.73-keV γ-rays in gold target should be taken into account when determining the efficiency. And it is easy to see that the depth distribution of196Au at axial direction in gold target is not uniform.So the attenuation coefficients of 355.73-keV γ-rays in different depths of the target are different.As the photoneutron reaction rate in different depths of the target can indicate the relative depth distribution of196Au at axial direction,we can change the thickness of gold target and calculate the total attenuation coefficient.The total attenuation coefficient can be written as

    where σis the total absorption cross section of 355.73-keV γ-ray in gold,whose value is 87.89 b referred from Photon Cross Sections Database,NIST.Thus the absolute efficiency of 355.73-keV γ-ray by considering the absorption in gold target is determined as follows:

    So the counts of 355.73-keV γ-rays detected in HPGe will be

    Finally,the efficiency was obtained to be ε=(1.741±0.002)×10?2.The total absorption cross section σtwas determined by measured the attenuation of 9.17-MeV γ-ray in gold target with the following equation:

    Thus the value of σtwas obtained to be 17.37±2.61 b.

    According to Eq.(3)and Eq.(8),the cross section of197Au(γ,n)at 9.17 MeV will be written as

    where

    According to the equation above,the cross section of197Au(γ,n)at 9.17 MeV can be obtained,and the results and uncertainties from two targets were shown in Table 3.

    Table 3.Cross section of 197Au(γ,n)at 9.17 MeV along with the statistical()and systematic()uncertainties.

    Table 3.Cross section of 197Au(γ,n)at 9.17 MeV along with the statistical()and systematic()uncertainties.

    Sample Ndet NReaction σg/mb ?σgs tat/mb ?σgsy st/mb 1 1566±49 1.01±0.03×106 40.1±6.9 6.27 0.63 2 6610±100 1.09±0.02×106 40.4±6.9 6.27 0.63

    4.Summary

    The measurement of photoneutron cross section is important for studying the abilities of photonuclear transmutation in nuclear wastes disposal.We came up with a new method for measuring the cross section of photoneutron reaction based on a mono-energetic γ-ray source from(p,γ)reaction.We determined the cross section of197Au(γ,n)at 9.17 MeV by using of γ-rays from13C(p,γ)14N reaction.The value obtained was σg=40.3±6.9 mb.We compared our results with the values 48.34±2.13 mb and 45±5 mb obtained by Osamu ITOH[9]and A.VEYSSIERE[11]respectively.

    Acknowledgments

    One of the authors(Dang)is grateful to professors Chuang-Ye He and Bing Guo for the guide on experiment.The author would like to give sincere gratitude to Mr.Diao for equipment supply of low-background and anti-Compton HPGe detector system.I wish to thank Dr.Qi-Wen Fan for making the target.I would like to give sincere gratitude to the staff in 2×1.7-MV tandem accelerator laboratory at China Institute of Atomic Energy for support in experiment.

    猜你喜歡
    永樂
    “衣冠楚楚”的《永樂大典》
    自己睡覺
    滄桑600年
    黨員文摘(2024年3期)2024-03-08 07:51:33
    自己睡覺
    彩色筆動起來
    洪武、永樂、宣德、成化古瓷鑒定技巧
    藝術品鑒(2020年10期)2020-11-27 01:54:04
    《永樂大典》所見明人佚集二種
    天一閣文叢(2018年0期)2018-11-29 07:48:40
    從倫敦書店到“書格”——《永樂大典》卷一三九九一的重現(xiàn)與重生
    天一閣文叢(2018年0期)2018-11-29 07:48:16
    楊永樂油畫作品
    大眾文藝(2016年2期)2016-03-08 01:30:48
    尋找《永樂大典》
    国产91av在线免费观看| 村上凉子中文字幕在线| 国产亚洲91精品色在线| 春色校园在线视频观看| 亚洲天堂国产精品一区在线| 高清午夜精品一区二区三区| 精华霜和精华液先用哪个| 色哟哟·www| 亚洲av免费高清在线观看| 99久国产av精品| 亚洲国产日韩欧美精品在线观看| 国产女主播在线喷水免费视频网站 | 女人久久www免费人成看片 | 精品久久久久久久久久久久久| 高清视频免费观看一区二区 | 国产女主播在线喷水免费视频网站 | 综合色av麻豆| 国产成年人精品一区二区| 99久久精品热视频| 亚洲av免费在线观看| 七月丁香在线播放| 色噜噜av男人的天堂激情| eeuss影院久久| 久久99蜜桃精品久久| 国产免费男女视频| 成人欧美大片| 中文字幕久久专区| 免费一级毛片在线播放高清视频| 天天一区二区日本电影三级| 日本黄大片高清| 午夜福利在线在线| 村上凉子中文字幕在线| 亚洲精品成人久久久久久| 五月伊人婷婷丁香| 国产真实伦视频高清在线观看| 亚洲乱码一区二区免费版| 又粗又爽又猛毛片免费看| 永久网站在线| 免费av不卡在线播放| 内射极品少妇av片p| 黄色配什么色好看| 亚洲国产精品合色在线| 三级男女做爰猛烈吃奶摸视频| 26uuu在线亚洲综合色| 精品免费久久久久久久清纯| 亚洲国产成人一精品久久久| 黄色日韩在线| 亚洲国产欧洲综合997久久,| 最近2019中文字幕mv第一页| 欧美日韩国产亚洲二区| 男女下面进入的视频免费午夜| 亚洲av熟女| 国产v大片淫在线免费观看| 欧美+日韩+精品| 亚洲精品,欧美精品| 国产亚洲最大av| 亚洲成人久久爱视频| 亚洲在线自拍视频| 91午夜精品亚洲一区二区三区| 男女边吃奶边做爰视频| 免费看av在线观看网站| 亚洲av二区三区四区| 国内揄拍国产精品人妻在线| 能在线免费看毛片的网站| 亚洲av不卡在线观看| 欧美激情久久久久久爽电影| 久久精品夜夜夜夜夜久久蜜豆| 欧美zozozo另类| 久久久久久久国产电影| 最近中文字幕2019免费版| 亚洲国产精品专区欧美| av国产久精品久网站免费入址| 一卡2卡三卡四卡精品乱码亚洲| 色综合色国产| 亚洲怡红院男人天堂| 国产精品久久视频播放| 亚洲三级黄色毛片| 午夜福利网站1000一区二区三区| 欧美性猛交╳xxx乱大交人| 久久99热6这里只有精品| 亚洲性久久影院| 哪个播放器可以免费观看大片| 日日干狠狠操夜夜爽| 久久久久久久国产电影| 国产成人精品久久久久久| 久久人人爽人人爽人人片va| a级毛色黄片| 亚洲,欧美,日韩| 久久国产乱子免费精品| 最后的刺客免费高清国语| 久久人妻av系列| 亚洲欧美精品自产自拍| 听说在线观看完整版免费高清| 啦啦啦啦在线视频资源| 一个人看的www免费观看视频| 99热网站在线观看| 国产美女午夜福利| 九草在线视频观看| 久久这里只有精品中国| 国产老妇伦熟女老妇高清| 99久久精品一区二区三区| 国产三级中文精品| av在线播放精品| 中文字幕亚洲精品专区| 午夜福利在线观看免费完整高清在| 国产男人的电影天堂91| 日本黄色片子视频| 亚洲av二区三区四区| 亚洲自偷自拍三级| 能在线免费看毛片的网站| 国产成人精品一,二区| 中文天堂在线官网| av在线播放精品| 国产乱来视频区| 国产精品永久免费网站| 男女边吃奶边做爰视频| 97在线视频观看| 亚洲av电影在线观看一区二区三区 | or卡值多少钱| 亚洲aⅴ乱码一区二区在线播放| 亚洲国产最新在线播放| 中文乱码字字幕精品一区二区三区 | 深爱激情五月婷婷| 18禁在线无遮挡免费观看视频| 亚洲人与动物交配视频| 别揉我奶头 嗯啊视频| 国产激情偷乱视频一区二区| 欧美日韩一区二区视频在线观看视频在线 | av专区在线播放| 亚洲激情五月婷婷啪啪| 校园人妻丝袜中文字幕| 亚洲不卡免费看| 精品熟女少妇av免费看| 乱人视频在线观看| 老女人水多毛片| 午夜福利高清视频| 99久久无色码亚洲精品果冻| 成人欧美大片| 婷婷六月久久综合丁香| 亚洲av免费高清在线观看| 看黄色毛片网站| 国产精品综合久久久久久久免费| 99热网站在线观看| av在线天堂中文字幕| 国模一区二区三区四区视频| 热99re8久久精品国产| 99久久成人亚洲精品观看| 一级毛片aaaaaa免费看小| 日韩在线高清观看一区二区三区| 日日摸夜夜添夜夜添av毛片| 你懂的网址亚洲精品在线观看 | 能在线免费观看的黄片| 韩国高清视频一区二区三区| 亚洲在线观看片| 97超碰精品成人国产| 欧美日韩综合久久久久久| 亚洲精品,欧美精品| 久久人人爽人人爽人人片va| av卡一久久| 国产又黄又爽又无遮挡在线| 欧美日韩在线观看h| 国产精品久久视频播放| 亚洲无线观看免费| 国产精品一区二区三区四区久久| 99久国产av精品| av.在线天堂| 亚洲欧洲日产国产| 色尼玛亚洲综合影院| 三级国产精品欧美在线观看| 欧美激情在线99| 成人美女网站在线观看视频| 欧美日韩在线观看h| 性色avwww在线观看| 小蜜桃在线观看免费完整版高清| 久久久久久久久大av| 久久精品夜色国产| 九九在线视频观看精品| 淫秽高清视频在线观看| 日本一本二区三区精品| 亚洲精品成人久久久久久| 午夜福利视频1000在线观看| av在线亚洲专区| 菩萨蛮人人尽说江南好唐韦庄 | 在线天堂最新版资源| 久久久久久久午夜电影| 又爽又黄a免费视频| 日韩精品青青久久久久久| 欧美激情在线99| 乱码一卡2卡4卡精品| 白带黄色成豆腐渣| 能在线免费观看的黄片| 啦啦啦啦在线视频资源| 日本一本二区三区精品| 久久精品国产亚洲av涩爱| 精品熟女少妇av免费看| 草草在线视频免费看| 乱人视频在线观看| 欧美色视频一区免费| 99久久成人亚洲精品观看| 欧美日本视频| 精品一区二区三区人妻视频| 色综合亚洲欧美另类图片| 亚洲国产精品成人综合色| 久热久热在线精品观看| 国产成人一区二区在线| 22中文网久久字幕| 一本—道久久a久久精品蜜桃钙片 精品乱码久久久久久99久播 | 久久精品夜色国产| 小蜜桃在线观看免费完整版高清| 精品人妻偷拍中文字幕| 国产不卡一卡二| 午夜福利高清视频| 亚洲一级一片aⅴ在线观看| 六月丁香七月| 麻豆av噜噜一区二区三区| 一级毛片aaaaaa免费看小| 天天躁夜夜躁狠狠久久av| 在线观看美女被高潮喷水网站| 男人狂女人下面高潮的视频| 国产伦在线观看视频一区| 国产精品一区二区性色av| 久久99精品国语久久久| 丰满人妻一区二区三区视频av| 免费大片18禁| 国产精品国产三级国产专区5o | 成人性生交大片免费视频hd| 欧美另类亚洲清纯唯美| 熟妇人妻久久中文字幕3abv| 男的添女的下面高潮视频| 色综合站精品国产| 狂野欧美白嫩少妇大欣赏| 日韩一区二区视频免费看| 午夜福利在线观看免费完整高清在| 久久久久久久久久黄片| 国产精品嫩草影院av在线观看| 久久精品国产鲁丝片午夜精品| h日本视频在线播放| 国产一区二区在线av高清观看| 免费黄色在线免费观看| 国产伦在线观看视频一区| 日日啪夜夜撸| 国产亚洲午夜精品一区二区久久 | 日韩av在线免费看完整版不卡| 精品久久国产蜜桃| 国产黄色视频一区二区在线观看 | 亚洲18禁久久av| av国产久精品久网站免费入址| 成人二区视频| 日韩成人伦理影院| 国产一区二区三区av在线| 在线观看美女被高潮喷水网站| 麻豆av噜噜一区二区三区| 黄色配什么色好看| 在线观看美女被高潮喷水网站| 中文字幕久久专区| 97超视频在线观看视频| 国产精品永久免费网站| 久久精品久久久久久噜噜老黄 | 亚洲av成人精品一二三区| 三级毛片av免费| 欧美区成人在线视频| 国产黄色小视频在线观看| 久久精品熟女亚洲av麻豆精品 | 九色成人免费人妻av| 蜜桃久久精品国产亚洲av| 久久久久久九九精品二区国产| 我要搜黄色片| 又爽又黄a免费视频| 欧美最新免费一区二区三区| 亚洲国产欧美在线一区| 国内精品宾馆在线| 国产 一区 欧美 日韩| 欧美三级亚洲精品| 亚洲一级一片aⅴ在线观看| 亚洲av免费高清在线观看| 亚洲在线自拍视频| 国产女主播在线喷水免费视频网站 | 男女啪啪激烈高潮av片| 青春草亚洲视频在线观看| 国产v大片淫在线免费观看| 免费av不卡在线播放| 中文精品一卡2卡3卡4更新| 99热6这里只有精品| 两性午夜刺激爽爽歪歪视频在线观看| 国产精品av视频在线免费观看| 久久99热6这里只有精品| 中文天堂在线官网| 亚洲国产精品成人久久小说| 人妻夜夜爽99麻豆av| 亚洲国产最新在线播放| 一级黄色大片毛片| 亚洲五月天丁香| 特级一级黄色大片| 狂野欧美激情性xxxx在线观看| 国产在视频线在精品| 免费观看a级毛片全部| 午夜激情福利司机影院| 久久精品人妻少妇| 国产成人aa在线观看| 精品国产一区二区三区久久久樱花 | 国产一区二区在线观看日韩| 国产男人的电影天堂91| 热99re8久久精品国产| 三级经典国产精品| 一边亲一边摸免费视频| 久久久久久久国产电影| 天堂中文最新版在线下载 | 最近手机中文字幕大全| 国产色婷婷99| 亚洲精品久久久久久婷婷小说 | 亚洲精品乱码久久久v下载方式| 亚洲电影在线观看av| 国产精品爽爽va在线观看网站| 国产一级毛片在线| 全区人妻精品视频| 变态另类丝袜制服| 桃色一区二区三区在线观看| 白带黄色成豆腐渣| 国产欧美另类精品又又久久亚洲欧美| 麻豆乱淫一区二区| 黄色日韩在线| 精品午夜福利在线看| 亚洲欧美精品综合久久99| 日本-黄色视频高清免费观看| 午夜福利在线在线| 精品久久久久久久人妻蜜臀av| 国产熟女欧美一区二区| 免费av毛片视频| 能在线免费观看的黄片| 国产在线男女| 1000部很黄的大片| 亚洲精品国产成人久久av| 午夜福利成人在线免费观看| av.在线天堂| 欧美性猛交╳xxx乱大交人| 99久久人妻综合| 国产女主播在线喷水免费视频网站 | 岛国毛片在线播放| 亚洲自偷自拍三级| 美女高潮的动态| 精品不卡国产一区二区三区| 国产精品爽爽va在线观看网站| 久久精品国产亚洲av天美| 久久热精品热| 欧美成人a在线观看| 免费一级毛片在线播放高清视频| 久久国产乱子免费精品| 六月丁香七月| 国产午夜精品论理片| 亚洲精品国产成人久久av| 99久久精品一区二区三区| 麻豆国产97在线/欧美| 精品国内亚洲2022精品成人| 麻豆国产97在线/欧美| 欧美97在线视频| 国产精品一区二区三区四区久久| 青春草视频在线免费观看| 国产一区亚洲一区在线观看| 国产淫语在线视频| 少妇人妻一区二区三区视频| 51国产日韩欧美| ponron亚洲| av女优亚洲男人天堂| 精品一区二区三区人妻视频| 久久久色成人| 精品人妻偷拍中文字幕| 国产精品国产三级国产专区5o | 国产久久久一区二区三区| 国产一区二区在线观看日韩| 日本三级黄在线观看| 国内揄拍国产精品人妻在线| av黄色大香蕉| 亚洲av福利一区| 日韩视频在线欧美| 国产欧美另类精品又又久久亚洲欧美| 久热久热在线精品观看| 欧美精品一区二区大全| 免费无遮挡裸体视频| 国产一区二区在线观看日韩| 国产在视频线精品| 日韩在线高清观看一区二区三区| 欧美一区二区国产精品久久精品| 97超碰精品成人国产| 青春草亚洲视频在线观看| 久久久久免费精品人妻一区二区| 一夜夜www| 岛国毛片在线播放| 丰满少妇做爰视频| 三级国产精品欧美在线观看| 亚洲人与动物交配视频| 村上凉子中文字幕在线| 亚洲av电影不卡..在线观看| 精品一区二区免费观看| 亚洲人成网站高清观看| 日本猛色少妇xxxxx猛交久久| 精品久久久久久久人妻蜜臀av| 淫秽高清视频在线观看| 久久精品国产亚洲av涩爱| 久久6这里有精品| 精品酒店卫生间| 美女内射精品一级片tv| 欧美日韩一区二区视频在线观看视频在线 | 美女被艹到高潮喷水动态| 国产成人福利小说| 日韩在线高清观看一区二区三区| 日本免费a在线| 国产精品不卡视频一区二区| 国产成年人精品一区二区| 久久久久九九精品影院| 在现免费观看毛片| 亚洲国产日韩欧美精品在线观看| 久久久久精品久久久久真实原创| 99在线视频只有这里精品首页| 少妇高潮的动态图| 亚洲av电影在线观看一区二区三区 | 亚洲欧美日韩东京热| 国产黄a三级三级三级人| 色视频www国产| 男女啪啪激烈高潮av片| 国产淫片久久久久久久久| 伊人久久精品亚洲午夜| 又粗又硬又长又爽又黄的视频| 老司机福利观看| 国产极品天堂在线| 亚洲av免费高清在线观看| 亚洲av二区三区四区| 久久久精品欧美日韩精品| 久久久精品大字幕| 免费av毛片视频| 老司机福利观看| 2021天堂中文幕一二区在线观| 久久久久网色| 国产熟女欧美一区二区| 国产免费视频播放在线视频 | 日韩,欧美,国产一区二区三区 | 国产精品人妻久久久久久| 国产成人精品婷婷| 国产又黄又爽又无遮挡在线| 亚洲欧洲国产日韩| 特大巨黑吊av在线直播| 欧美精品一区二区大全| av卡一久久| 嫩草影院入口| 免费看av在线观看网站| 国产伦一二天堂av在线观看| 午夜福利网站1000一区二区三区| 国模一区二区三区四区视频| 欧美日韩国产亚洲二区| 床上黄色一级片| 观看免费一级毛片| 91av网一区二区| 熟女人妻精品中文字幕| 夜夜看夜夜爽夜夜摸| 国产免费视频播放在线视频 | 蜜桃久久精品国产亚洲av| 日本与韩国留学比较| 国产成人aa在线观看| 日本-黄色视频高清免费观看| 国产精品久久视频播放| 岛国毛片在线播放| 校园人妻丝袜中文字幕| 日日摸夜夜添夜夜添av毛片| 久久久久久久午夜电影| 国产免费又黄又爽又色| 国产成人91sexporn| 久久久久久久国产电影| 国产一区二区三区av在线| 国产精品国产三级国产专区5o | 国产麻豆成人av免费视频| 日本黄大片高清| 亚洲综合精品二区| 九九在线视频观看精品| 一区二区三区免费毛片| www.av在线官网国产| 校园人妻丝袜中文字幕| 麻豆成人av视频| 一级二级三级毛片免费看| 十八禁国产超污无遮挡网站| 亚洲av成人精品一二三区| 亚洲人成网站在线播| 免费播放大片免费观看视频在线观看 | 亚洲av电影不卡..在线观看| 欧美日韩在线观看h| 婷婷色av中文字幕| 亚洲欧美日韩无卡精品| 桃色一区二区三区在线观看| 日产精品乱码卡一卡2卡三| 最近的中文字幕免费完整| 国产精品一区二区性色av| 亚洲婷婷狠狠爱综合网| 看十八女毛片水多多多| 久久午夜福利片| 人体艺术视频欧美日本| 一级毛片我不卡| 在线a可以看的网站| 18禁在线无遮挡免费观看视频| 可以在线观看毛片的网站| 日韩成人伦理影院| 2021天堂中文幕一二区在线观| 国产乱来视频区| 成人毛片a级毛片在线播放| 亚洲四区av| 人人妻人人澡人人爽人人夜夜 | 中文欧美无线码| 免费看av在线观看网站| 3wmmmm亚洲av在线观看| 高清毛片免费看| 国产成年人精品一区二区| 亚洲av成人精品一区久久| 亚洲精品色激情综合| 国产高清视频在线观看网站| 亚洲在线观看片| 国产精品日韩av在线免费观看| 啦啦啦韩国在线观看视频| 精品久久久久久久久av| 国产又色又爽无遮挡免| 成人漫画全彩无遮挡| 黄色配什么色好看| 午夜福利在线观看吧| 欧美最新免费一区二区三区| 最后的刺客免费高清国语| av天堂中文字幕网| 青春草亚洲视频在线观看| 人人妻人人看人人澡| 中国国产av一级| 伦精品一区二区三区| 国产精品女同一区二区软件| 欧美另类亚洲清纯唯美| av专区在线播放| 亚洲精品色激情综合| av在线老鸭窝| 在线免费观看的www视频| 99热这里只有是精品50| 色吧在线观看| 日韩一区二区视频免费看| 偷拍熟女少妇极品色| 欧美不卡视频在线免费观看| 国产精品久久视频播放| 身体一侧抽搐| 人妻系列 视频| 看非洲黑人一级黄片| 一卡2卡三卡四卡精品乱码亚洲| 久久亚洲精品不卡| 国产成人精品一,二区| 国产黄a三级三级三级人| 亚洲欧美成人精品一区二区| 两个人视频免费观看高清| 国内精品一区二区在线观看| 亚洲婷婷狠狠爱综合网| 国产精品一区二区性色av| 国产成人aa在线观看| 亚洲真实伦在线观看| 国产精品一二三区在线看| 黄片无遮挡物在线观看| 麻豆av噜噜一区二区三区| 成人三级黄色视频| 精品99又大又爽又粗少妇毛片| 国产不卡一卡二| 又爽又黄a免费视频| 美女黄网站色视频| 成年av动漫网址| 国产真实伦视频高清在线观看| 国产视频内射| av在线观看视频网站免费| 熟女人妻精品中文字幕| 国产精品一区二区性色av| 日本免费a在线| 午夜福利成人在线免费观看| 我的女老师完整版在线观看| 99热精品在线国产| 成人特级av手机在线观看| 97超碰精品成人国产| 免费看美女性在线毛片视频| 欧美激情国产日韩精品一区| 99九九线精品视频在线观看视频| 中文资源天堂在线| 视频中文字幕在线观看| 色综合色国产| 国语对白做爰xxxⅹ性视频网站| 国产极品精品免费视频能看的| 人妻少妇偷人精品九色| av在线观看视频网站免费| 特大巨黑吊av在线直播| 日韩制服骚丝袜av| 国产色婷婷99| 91久久精品国产一区二区三区| 国产精品人妻久久久久久| 最近中文字幕高清免费大全6| 人体艺术视频欧美日本| 三级毛片av免费| 国产一区二区在线观看日韩| 久久久久久久亚洲中文字幕| 九九热线精品视视频播放| 亚洲欧美日韩东京热| 18禁裸乳无遮挡免费网站照片| 国产女主播在线喷水免费视频网站 | 久久精品国产自在天天线| 国产精品久久电影中文字幕| 全区人妻精品视频| 国产精品福利在线免费观看| 少妇猛男粗大的猛烈进出视频 | 国产高清视频在线观看网站| 日韩一区二区视频免费看| 国产私拍福利视频在线观看| 一夜夜www| 黄色日韩在线| 在线免费十八禁| 亚洲欧美精品专区久久| 亚洲欧美精品综合久久99| 精品一区二区免费观看| 日韩视频在线欧美| or卡值多少钱| 三级经典国产精品| 日韩亚洲欧美综合| av播播在线观看一区|