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   26129篇
  免费   1414篇
各国政治   1061篇
工人农民   1129篇
世界政治   1773篇
外交国际关系   800篇
法律   17432篇
中国共产党   2篇
中国政治   162篇
政治理论   5013篇
综合类   171篇
  2021年   124篇
  2020年   491篇
  2019年   555篇
  2018年   716篇
  2017年   749篇
  2016年   822篇
  2015年   629篇
  2014年   682篇
  2013年   2602篇
  2012年   657篇
  2011年   727篇
  2010年   698篇
  2009年   746篇
  2008年   728篇
  2007年   726篇
  2006年   743篇
  2005年   642篇
  2004年   625篇
  2003年   557篇
  2002年   602篇
  2001年   995篇
  2000年   886篇
  1999年   701篇
  1998年   378篇
  1997年   278篇
  1996年   311篇
  1995年   304篇
  1994年   294篇
  1993年   296篇
  1992年   490篇
  1991年   512篇
  1990年   486篇
  1989年   488篇
  1988年   492篇
  1987年   454篇
  1986年   541篇
  1985年   536篇
  1984年   438篇
  1983年   411篇
  1982年   301篇
  1981年   268篇
  1980年   239篇
  1979年   339篇
  1978年   192篇
  1977年   191篇
  1976年   162篇
  1975年   158篇
  1974年   202篇
  1973年   155篇
  1972年   150篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
111.
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   
112.
A case of the sudden death of a 14-month-old girl due to massive hemorrhage in a primitive neuroectodermal tumor (PNET) is presented along with a review of the relevant literature. PNET is a rare, malignant brain neoplasm occurring predominantly in children.  相似文献   
113.
114.
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   
115.
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   
116.
Dilutions of 100 serum samples of various GM phenotypes were dotted onto a nitrocellulose membrane. The serum dot-blots were detected with peroxidase-labeled anti-G3M T monoclonal antibody (anti-G3M T MAb). Up to a 1 : 256 dilution could be G3M T-typed correctly. By use of anti-G3M T MAb and peroxidase-labeled anti-mouse IgG or the biotin-avidin system instead of use of labeled anti-G3M T MAb, up to a 1 : 512 or 1 : 1024, respectively, dilution was typable. As with previous work with G3M G MAb, the dot immunobinding (DIB) method for G3M T typing was found very simple and practical.  相似文献   
117.
A technique was developed for Gm/Km typing of bloodstains and sera in U-bottom microtiter plates. Gm/Km typing of sweat and urine samples was also attempted with limited success.  相似文献   
118.
119.
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   
120.
HIV infection is now perceived as the end stage of a chronic disease that is spreading most rapidly among blacks and Hispanics. The politics of the HIV epidemic in the 1980s were dominated by four interacting factors: fear and fascination; who had the disease and to whom it seemed to be spreading; the endemic problems of United States social policy; and the impact on policy of advances in scientific knowledge. This paper analyzes the political history of each of these factors and describes the dominant policies of the federal government and the states regarding HIV in the areas of surveillance, prevention, research, and financing. Four uncertainties will have a profound influence on the future politics of the HIV epidemic: how the states and the federal government will address the general problems of paying for the care of people with chronic diseases and providing access to care for the uninsured and the underinsured; the number and distribution of the sexual behaviors that transmit infection with HIV and the effectiveness of policies to persuade people to modify these behaviors; precisely who uses addictive drugs and the effectiveness of measures to change their behavior; and the natural history of the virus.  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