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   17298篇
  免费   508篇
各国政治   716篇
工人农民   672篇
世界政治   1450篇
外交国际关系   603篇
法律   10360篇
中国共产党   2篇
中国政治   78篇
政治理论   3746篇
综合类   179篇
  2020年   208篇
  2019年   251篇
  2018年   330篇
  2017年   395篇
  2016年   425篇
  2015年   299篇
  2014年   340篇
  2013年   1700篇
  2012年   410篇
  2011年   433篇
  2010年   346篇
  2009年   394篇
  2008年   453篇
  2007年   470篇
  2006年   446篇
  2005年   397篇
  2004年   397篇
  2003年   422篇
  2002年   384篇
  2001年   686篇
  2000年   617篇
  1999年   507篇
  1998年   288篇
  1997年   246篇
  1996年   208篇
  1995年   208篇
  1994年   250篇
  1993年   220篇
  1992年   339篇
  1991年   374篇
  1990年   329篇
  1989年   348篇
  1988年   322篇
  1987年   336篇
  1986年   340篇
  1985年   335篇
  1984年   292篇
  1983年   318篇
  1982年   259篇
  1981年   239篇
  1980年   179篇
  1979年   248篇
  1978年   167篇
  1977年   144篇
  1976年   132篇
  1975年   123篇
  1974年   139篇
  1973年   118篇
  1972年   117篇
  1971年   96篇
排序方式: 共有10000条查询结果,搜索用时 46 毫秒
121.
122.
123.
A 6-month-old girl died suddenly without any previous symptoms of heart failure. Autopsy examination showed cardiomegaly (97 g) with a severely fibrotized myocardium. The left coronary artery was originating from the pulmonary artery. Histologically, the myocardium showed myocardial infarcts of different ages, as well as grossly thickened arterial branches due to increased flow in left-right shunt. We suggest that rare anomalies of the coronary arteries should be considered in the autopsies of suspected sudden infant death syndrome cases.  相似文献   
124.
The impact of high temperatures (24 to 39 degrees C) and low to moderately high humidities (20 to 70%) on the applicability of TLC systems for drug identification was studied during a 6 month climatologic cycle in Burkina Faso (West Africa). In general, the Rf values as observed on the plates were found to be substantially affected as compared with values obtained at temperate climates. Some TLC systems were more affected than others and the largest deviations of up to 30 Rf units were at low humidities. Tropical conditions also had a negative effect on the reproducibility of Rf values. However, when an Rf-correction procedure was applied, using reference mixtures of known drugs on each plate, accuracy as well as reproducibility of the resulting Rfc values were drastically improved and data thus corrected were found to be compatible with existing TLC data bases developed under moderate climatological conditions. The impact of high to extremely high humidities (70 to 100%) remains to be investigated.  相似文献   
125.
Washington University v. Catalona revolves around ownership of tissue samples provided by patients for research purposes, raising significant ethical and legal questions concerning patient rights, current human research practices, and the treatment of samples as capital resources by the research institution.  相似文献   
126.
In this study, a new method was developed for the impurity profiling of illicit MDMA tablets. The extraction efficiency, linearity, repeatability and reproducibility of the method were evaluated. Eighty two MDMA tablets coming from presumed unrelated large seizures in 2004 (n >500 tablets) were analyzed by gas chromatography mass spectrometry (GC-MS) in order to assess the discrimination power of the method. The latter was found to be practical, robust, relatively easy to perform, highly discriminative and yielding good chromatography. In addition, some new impurities were detected and identified. Their chemical structures and mass spectra are reported.  相似文献   
127.
128.
In a case of suicidal application of electricity differences between the rectal temperature of the body and the suspected time of death were observed.In order to answer the question whether an electric current from hand to hand over >30 min led to a rise in body temperature FEM-based computer simulations and animal experiments were carried out. Both resulted in a warming of the soft parts in the arm without warming the body core. Thus a temperature-based estimation of the time since death can also be used in cases with electricity as the cause of death. Besides, in the animal experiment we found a spontaneous rise in the body core temperature even without application of electricity which may be a reason for the typical temperature plateau after death.  相似文献   
129.
130.
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