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   22002篇
  免费   1316篇
各国政治   893篇
工人农民   1005篇
世界政治   1554篇
外交国际关系   725篇
法律   14940篇
中国共产党   2篇
中国政治   143篇
政治理论   3952篇
综合类   104篇
  2021年   124篇
  2020年   477篇
  2019年   529篇
  2018年   676篇
  2017年   674篇
  2016年   752篇
  2015年   557篇
  2014年   627篇
  2013年   2292篇
  2012年   589篇
  2011年   631篇
  2010年   633篇
  2009年   671篇
  2008年   643篇
  2007年   629篇
  2006年   631篇
  2005年   539篇
  2004年   561篇
  2003年   455篇
  2002年   488篇
  2001年   902篇
  2000年   798篇
  1999年   618篇
  1998年   307篇
  1997年   241篇
  1996年   233篇
  1995年   238篇
  1994年   214篇
  1993年   208篇
  1992年   395篇
  1991年   418篇
  1990年   394篇
  1989年   379篇
  1988年   391篇
  1987年   367篇
  1986年   395篇
  1985年   394篇
  1984年   324篇
  1983年   302篇
  1982年   226篇
  1981年   219篇
  1980年   172篇
  1979年   279篇
  1978年   156篇
  1977年   116篇
  1975年   128篇
  1974年   166篇
  1973年   126篇
  1972年   110篇
  1971年   97篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
71.
Esophageal and tracheal fistulas, which occur in 0.05% of medicolegal autopsies, were demonstrated in three cases by a postmortem radiographic technique using silicone rubber/lead oxide as a contrasting medium that vulcanizes at room temperature. In one 83-year-old male, a tracheoesophageal fistula was detected, which had developed after surgical repair of an esophageal rupture caused by a flexible fiberoptic endoscope. In a second case, carcinoma of the esophagus in a 78-year-old male had eroded the trachea and arcus of the aorta creating a fatal tracheoesophagoaortic fistula. In a third case, 55-year-old female developed a tracheobrachicephalic artery fistula as a result of an infiltrating cystic adenocarcinoma of the trachea, resulting in a fatal hemorrhage into the trachea. The results of this study indicate that diagnostic radiologic methods using a vulcanized contrasting medium are useful in supplementing normal dissection in autopsy cases with suspected fistulas of the esophagus or trachea.  相似文献   
72.
73.
We investigated the differences in the levels of carboxyhemoglobin (COHb), cyanide (HCN) and petroleum fuels (gasoline and kerosene) between left and right ventricular bloods from fire victims. COHb was slightly, and HCN and petroleum fuels were markedly higher levels in the left than those in the right. These effects were so called 'first pass phenomena' due to the circulation, diffusion and metabolization before the deaths of fire victims.  相似文献   
74.
Attributions of blame for the first and latest episodes of violence were assessed in a sample of 139 couples who were referred to a mandatory domestic violence treatment program in the military. Use of a methodology which allows for reports of nonmutually exclusive categories of attribution from both members of the dyad revealed more complex patterns of attributions than reflected in the existing literature. In addition, there were low rates of agreement within couples as to who was to blame for the violence. Although both men and women exhibited a high frequency of blaming their partner for both episodes of violence, men were significantly more likely to blame themselves for the latest than for the first episode. Attributions of blame were related to contextual variables in both men and women. Sex specific relationships emerged. These results were discussed with specific reference to predictions derived from attribution theory and their clinical implications.  相似文献   
75.
A minisatellite probe, MZ 1.3, detecting hypervariable fragment patterns was isolated from a human genomic library. A repetitive sequence of 27 bp length was identified which is contained in the probe approx. 40 times. The MZ 1.3 repeat shows variable homology of 53-73% to the repetitive sequence of the protein III gene of the bacteriophage M13 genome. Polymorphic restriction fragment patterns were found with MZ 1.3 using the enzymes Hinf I, BstN I, Hae III, Mbo I, PstI/Pvu II, and Rsa I. An average of 18 polymorphic fragments was observed using Hinf I as enzyme. The band sharing frequency after Hinf I digestion among unrelated individuals was determined to be 23.8 +/- 7.2%. An example for the application of MZ 1.3 to paternity testing in an incest case is given. The probe can be used with radioactive or non-radioactive detection systems. An approach is presented to compare polymorphic fragment patterns from individuals obtained by independent gel runs on the basis of relative band positions (RBP) and calculated in a computerized analysis.  相似文献   
76.
Good gas chromatography (GC) separation of molecules is essential for clean gas chromatography/mass spectrometry (GC/MS) confirmation of compounds. The trifluoro derivatives of ephedrine (E) and methamphetamine (MA) coelute on dimethyl silicone capillary columns, such as DB-1, which are most commonly used by chromatographers. Methods are described to separate E and MA to aid GC/MS confirmations of methamphetamine, ephedrine, or both E and MA together, whichever may be present in Enzyme Immunoassay (EIA)-analyzed amphetamine-positive urine samples. The use of the heptafluoro derivatives of E and MA on a DB-1 column, or the trifluoro derivatives of E and MA on a DB-17 column, is suggested for good gas chromatographic separation.  相似文献   
77.
One case of the erroneous administration of deslanoside and high level of drug in antemortem plasma and postmortem specimens has been reported owing to the unusual surrounding circumstances. Deslanoside in antemortem plasma was determined by FPIA and the analysis was done by HPLC in the postmortem tissue samples. The analytical results and methods used in the examinations are discussed in the following paper.  相似文献   
78.
79.
Bloodstains were made with 200 microliters blood on each of 11 different common substrates to examine the effect of the stain carrier on the amount and quality of DNA recoverable. High-molecular-weight DNA was extracted from all samples after 2 days. The yield of DNA from each sample varied considerably, not only between the different stain carriers but also within a given category. With a DNA yield of up to 10 micrograms, paper, glass, nylon, wood, smooth leather and wool gave the best results, followed by blue denim and wallpaper (up to 6 micrograms), cotton fabric and carpeting (up to 4 micrograms) and suede (up to 2 micrograms). For several stain carriers the DNA-containing solution was contaminated by chemical substances, which in the case of the blue denim, suede, and carpet samples inhibited the digestion of the DNA with restriction enzymes and prevented DNA typing. The different textures of the stain carriers tested and (as for varying yields on the same carrier) the differing degree of loss of DNA during extraction and the physiological variation in the number of leukocytes in human blood are discussed as possible reasons for the wide range of variation in the amounts of DNA it was possible to extract.  相似文献   
80.
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