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   19419篇
  免费   576篇
各国政治   867篇
工人农民   743篇
世界政治   1627篇
外交国际关系   758篇
法律   11233篇
中国共产党   2篇
中国政治   113篇
政治理论   4431篇
综合类   221篇
  2021年   110篇
  2020年   238篇
  2019年   305篇
  2018年   392篇
  2017年   466篇
  2016年   493篇
  2015年   354篇
  2014年   431篇
  2013年   2013篇
  2012年   488篇
  2011年   494篇
  2010年   410篇
  2009年   452篇
  2008年   509篇
  2007年   547篇
  2006年   520篇
  2005年   459篇
  2004年   478篇
  2003年   490篇
  2002年   449篇
  2001年   724篇
  2000年   658篇
  1999年   549篇
  1998年   319篇
  1997年   272篇
  1996年   235篇
  1995年   238篇
  1994年   280篇
  1993年   257篇
  1992年   367篇
  1991年   389篇
  1990年   345篇
  1989年   374篇
  1988年   333篇
  1987年   358篇
  1986年   354篇
  1985年   359篇
  1984年   309篇
  1983年   345篇
  1982年   283篇
  1981年   261篇
  1980年   200篇
  1979年   259篇
  1978年   178篇
  1977年   155篇
  1976年   139篇
  1975年   136篇
  1974年   144篇
  1973年   128篇
  1972年   116篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
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   
92.
Much attention has been paid to the nature of parent-adolescent relationships, with a frequent conclusion being that it is a time of marked disagreement between parents and their adolescents. However, other literature suggests that this time is not inherently conflictual. The purpose of this study was to examine agreement and disagreement between mothers, fathers, and adolescents on specific issues. Then, adolescent adjustment was assessed, and the degree to which it was a function of congruence with parents was examined. A modified version of the Issues Checklist was used to measure intrafamily agreement; the Revised Behavior Problem Checklist and the Harter Scale of Child's Actual Competence were completed by adolescents' social studies teachers to assess adolescent functioning. Relative to their parents, adolescents reported that they should make more decisions alone, while both mothers and fathers reported that decisions should be made jointly among all family members. Only father-adolescent congruence was found consistently to be related to adolescent functioning. Possible explanations for the present results and relevant issues pertaining to family agreement are discussed.  相似文献   
93.
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   
94.
95.
The impact of research information depends on its ability to change beliefs or policy assumptions within the relevant audiences. As a hybrid of American and British systems, Canada's chosen decision-making structure for policy-making and its legislative framework for health insurance make these audiences unclear and not readily accessible. This factor and historical characteristics of the research community which made them only partially responsive to the values of decisionmakers provide an explanation for the limited past use of research information in Canadian health policy. More recently, improved responsiveness by researchers and an emerging definition of the audiences by legislative policymakers are bringing about a gradual increase in the potential impact of research at the levels of administrative and clinical policy. Because of continuing decision-making constraints on legislative policy, however, impact at this level is predicted to remain diffuse, with only cautious acceptance of the changes in beliefs implied by research.  相似文献   
96.
97.
98.
99.
China's experiments with democracy in this century were few in number, short in duration, and limited in their democratic characteristics. Democratic institutions malfunctioned in numerous ways. Nine sets of causes for the failure of Chinese democracy can be suggested: ideology, internal and external war, military intervention, Chinese political culture, underdevelopment, a peasant mass, flaws in the design of Chinese constitutions, moral failures by democratic politicians, or the lack of transactional benefits for military‐based elites in the process of democratic transition. Each of these factors is reviewed critically with an eye to its possible lessons.  相似文献   
100.
A 22-year-old Korean soldier, who had received blows to the neck and epigastrium from an officer 10 h earlier, suddenly died after massive hematemesis. He had been in relatively good health except for episodes of blood-tinged vomiting approximately 5 and 7 months prior to this event. Postmortem examination revealed angiodysplasia involving the gastroesophageal junction, and the stomach was distended with blood. No abnormal findings were present around the whole viscera, and the duodenum was free of blood. The pathologic significance of upper gastrointestinal angiodysplasia as a potential source of bleeding and a chronologic correlation between the trauma and bleeding are discussed.  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