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   11227篇
  免费   301篇
各国政治   477篇
工人农民   381篇
世界政治   801篇
外交国际关系   298篇
法律   6963篇
中国政治   100篇
政治理论   2420篇
综合类   88篇
  2020年   103篇
  2019年   158篇
  2018年   191篇
  2017年   219篇
  2016年   214篇
  2015年   167篇
  2014年   201篇
  2013年   994篇
  2012年   248篇
  2011年   278篇
  2010年   230篇
  2009年   286篇
  2008年   300篇
  2007年   288篇
  2006年   282篇
  2005年   260篇
  2004年   241篇
  2003年   257篇
  2002年   244篇
  2001年   425篇
  2000年   371篇
  1999年   303篇
  1998年   167篇
  1997年   132篇
  1996年   147篇
  1995年   141篇
  1994年   150篇
  1993年   148篇
  1992年   245篇
  1991年   260篇
  1990年   254篇
  1989年   258篇
  1988年   235篇
  1987年   240篇
  1986年   279篇
  1985年   276篇
  1984年   245篇
  1983年   227篇
  1982年   162篇
  1981年   133篇
  1980年   123篇
  1979年   164篇
  1978年   94篇
  1977年   121篇
  1976年   108篇
  1975年   79篇
  1974年   95篇
  1973年   87篇
  1972年   86篇
  1971年   74篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
51.
A gas chromatographic (GC) fingerprint method, based on the presence or absence of six congeners, was developed for illicit cocaine samples. The fingerprint utilizes the relative abundances of these congeners towards each other, disregarding cocaine as the main constituent, and can be expressed numerically or graphically in the form of pictograms for rapid visual comparison. The method can be applied directly to a solution of the sample in chloroform, without previous workup procedures. More than 70 unrelated samples were analyzed and a great variation was observed in the parameter composition. On the other hand, a remarkable similarity could be seen between related samples. The GC fingerprint method may be considered an important contribution for sample comparison, as is exemplified by a subdivision of the analyzed samples in different categories, based on the number and types of congeners found.  相似文献   
52.
53.
The polymerase chain reaction (PCR) method of specific gene amplification was used in casework to synthesize millions of copies of the polymorphic second exon of the human leukocyte antigen (HLA)-DQ alpha (or DQA1) locus from a variety of evidence samples. The HLA-DQ alpha allelic variants in the amplified deoxyribonucleic acid (DNA) were determined in a rapid non-radioactive test by hybridization to sequence-specific oligonucleotide probes in both the dot-blot and reverse dot-blot formats. This genetic typing system has been subjected to blind proficiency testing; the performance of this test in the analysis of experimentally mixed samples was also evaluated. As of August 1990, over 250 cases have been tested and more than 2000 individual evidence (bloodstains, semen stains, individual hairs, bone fragments, and tissue sections) and reference samples have been analyzed. The first 198 of these cases are summarized in this paper; in 65% of the cases with conclusive results a suspect was included, and in 35%, all suspects were excluded. Individual cases as well as some of the general issues relating to forensic science analysis and this genetic typing system are discussed. The high rate of exclusion reported here combined with the ability of PCR to type old evidence samples suggests the relevance of this genetic test for postconviction review; two cases in which the convicted suspect was excluded are discussed.  相似文献   
54.
An improved method has been developed for the reliable classification of different C1R genetic variant forms from human serum or plasma. The method combines the use of neuraminidase-digested samples followed by monodimensional isoelectric focusing in the pH range 5 to 8 followed by immunoblotting. The method yields a simple pattern, with one major band in homozygote and two major bands in heterozygote cases.  相似文献   
55.
Fabella  R. V. 《Public Choice》1996,89(3-4):325-337
Public Choice - We consider an economy where the rent value depends indirectly on value-adding investment of agents (thus indirectly endogenous) and the win-probability is a function of rent...  相似文献   
56.
57.
58.
We develop a model of the peace dividend and use it to predict the fiscal consequences of a reduction in the demand for military spending. The model is based on the assumption that the political process responds to political demands and costs in a way that maximizes net political benefits. The predictions of our model on how a peace dividend will be allocated over nonmilitary spending, tax relief, and deficit reduction is tested against the experience of eight major wars in United States history.  相似文献   
59.
A method ist described to determine the CO-content in the tissue of muscles. The prepared tissue is pulverized in a swinging mill at the temperature of liquid nitrogen. Parts of the powder are weighed into headspace vessels. Carbon monoxide ist ejected by a formerly described method and measured gaschromatographically. The Fe-content is determined after an acid disintegration by AAS. Acute intoxications lead to higher CO-contents in heart than in periphere muscles. Chronic exposure to carbon monoxide does not produce these differences.  相似文献   
60.
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