首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   12380篇
  免费   422篇
各国政治   794篇
工人农民   489篇
世界政治   1003篇
外交国际关系   685篇
法律   6704篇
中国政治   88篇
政治理论   2932篇
综合类   107篇
  2021年   69篇
  2020年   154篇
  2019年   200篇
  2018年   310篇
  2017年   337篇
  2016年   393篇
  2015年   242篇
  2014年   289篇
  2013年   1617篇
  2012年   321篇
  2011年   323篇
  2010年   292篇
  2009年   300篇
  2008年   376篇
  2007年   420篇
  2006年   396篇
  2005年   337篇
  2004年   333篇
  2003年   318篇
  2002年   288篇
  2001年   374篇
  2000年   328篇
  1999年   329篇
  1998年   175篇
  1997年   164篇
  1996年   141篇
  1995年   129篇
  1994年   141篇
  1993年   143篇
  1992年   187篇
  1991年   218篇
  1990年   213篇
  1989年   192篇
  1988年   208篇
  1987年   203篇
  1986年   206篇
  1985年   184篇
  1984年   168篇
  1983年   147篇
  1982年   108篇
  1981年   120篇
  1980年   86篇
  1979年   145篇
  1978年   104篇
  1977年   89篇
  1976年   70篇
  1975年   94篇
  1974年   109篇
  1973年   91篇
  1971年   62篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
951.
Subject Acquisition for Web-Based Surveys   总被引:1,自引:0,他引:1  
  相似文献   
952.
Beech H 《Time》2001,158(5):32
  相似文献   
953.
954.

Call for Papers

Conference Announcement  相似文献   
955.
A pesticide poisoning victim suspected initially as having died a natural death was autopsied. The victim was a 47-year-old male. Macroscopically, signs of acute death and, in particular, general erosion in the mucosa of the airways and esophagus were observed. In the gastric contents, which had a pungent smell and a greenish-brown color, 5.00 g/L of propanil, 1.27 g/L of carbaryl, 0.38 g/L of ethylbenzene, and 0.32 g/L of xylene were detected. In the blood (serum), 21.6 mg/L of propanil, 8.1 mg/L of carbaryl, 1.7 mg/L of ethylbenzene, and 4.0 mg/L of xylene were identified. Postmortem methemoglobinemia (45%) was recognized. The cause of death was considered to have been pesticide poisoning; propanil was probably most responsible for his death. The police considered the case to be "death with illness as the suspected cause." By performing an autopsy, however, we were able to clarify that the cause of death was pesticide poisoning.  相似文献   
956.
The authors tested whether use of an electro shock weapon (stun gun) leaves marks on skin which can be found in an exterior examination. On pig skin such marks could not be produced postmortally. An experiment on one of the authors caused reddish skin marks which persisted for about 2 h. Inability to act as promised by the weapons' manufacturers did not occur in our experiments, exactly as previously described by other authors. Use of an air tester which shoots barbed electrodes ought to produce bleedings if the electrodes actually penetrate the skin.  相似文献   
957.
Two species of blow flies (Diptera: Calliphoridae) were reared on tissues from rabbits administered different dosages of morphine. These species, Protophormia terraenovae and Calliphora vicina are among the first wave of insects colonizing a dead body. Two series of 3 rabbits were given dosages of 10, 20, and 40 mg/h of morphine over a 3 h period via ear artery perfusion. A morphine blood level plateau was attained after 1 h of perfusion. Two other rabbits were used as controls. Samples of tissues collected from rabbits using a coelioscopic technique were determined to have morphine concentrations similar to those encountered in human overdoses and were correlated with dosages of morphine administered. All samples from control rabbits were negative for morphine. Larvae and puparia of both species were regularly collected from each rabbit for toxicological analysis. Concentrations of morphine in larvae reared on rabbit carcasses containing morphine were significantly lower than concentrations found in the tissues. There was a decrease in concentration in morphine observed in transition from feeding 3rd instar larva to puparium. A correlation between larval concentration and tissue concentration was found only in feeding 3rd instar larvae.  相似文献   
958.
959.
We suggest a multi-layered system of three convergence criteria – similar to those used in the run-up to the European monetary union – that define the notion of "demonstrable progress" towards reaching the emission commitments under the Kyoto Protocol. These are the existence of an independently evaluated national emissions inventory, the level of domestic policies and measures, and the quantitative convergence of emissions towards the Kyoto target. While the first of these criteria constitutes a necessary condition for use of the Kyoto Mechanisms, the other two should determine the degree of participation allowed for any given Annex I country.  相似文献   
960.
Morphine was detected by immunohistochemistry on sections of third stage larvae of Calliphora vomitoria (Diptera, Calliphoridae) reared on minced beef meat previously treated with morphine hydrochloride. The detection was performed with an avidin-biotin-peroxidase-complex method. Positive specimens showed specific staining of the haemolymph and a more intense immunoreaction in an area located at the limit between exocuticle and endocuticle. These results constitute an evidence of morphine accumulation inside the cuticle of Diptera larvae during their development. During the pupariation, the larval cuticle is transformed into the sclerotized puparium. This study consequently points out the possibilities of analyzing empty pupariae when suitable tissues or living necrophagous insects are absent.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号