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   15103篇
  免费   483篇
各国政治   533篇
工人农民   1249篇
世界政治   634篇
外交国际关系   505篇
法律   9536篇
中国政治   34篇
政治理论   3060篇
综合类   35篇
  2020年   157篇
  2019年   167篇
  2018年   1420篇
  2017年   1379篇
  2016年   1212篇
  2015年   252篇
  2014年   191篇
  2013年   746篇
  2012年   331篇
  2011年   1062篇
  2010年   1193篇
  2009年   788篇
  2008年   870篇
  2007年   827篇
  2006年   167篇
  2005年   215篇
  2004年   340篇
  2003年   292篇
  2002年   161篇
  2001年   311篇
  2000年   254篇
  1999年   225篇
  1998年   106篇
  1997年   76篇
  1996年   85篇
  1995年   107篇
  1994年   106篇
  1993年   88篇
  1992年   152篇
  1991年   156篇
  1990年   145篇
  1989年   155篇
  1988年   122篇
  1987年   139篇
  1986年   124篇
  1985年   132篇
  1984年   110篇
  1983年   123篇
  1982年   87篇
  1981年   78篇
  1980年   55篇
  1979年   113篇
  1978年   76篇
  1977年   66篇
  1976年   50篇
  1975年   47篇
  1974年   55篇
  1973年   55篇
  1972年   44篇
  1968年   40篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
921.
We describe three unusual cases of suicide committed by health care workers. The aim of this paper was to analyze and evaluate the evidence of general diagnostic elements of poisoning in these cases.  相似文献   
922.
A news item in the newspaper, the Evening Star, for the Country, October 18, 1833, probably is the first report of a mail bomb in the United States. It is also likely to be the first defusing of a mail bomb. The device appeared to be extraordinarily sophisticated and would have likely worked had it not been for suspicions of the recipient of the bomb.  相似文献   
923.
Allele frequencies for the loci HLA-DQA1, LDLR, GYPA, HBGG, D7S8, GC, and D1S80 were determined for a sample population of unrelated individuals from Slovenia. All loci meet Hardy-Weinberg expectations, except the loci GYPA (p = 0.041) and D1S80 (p = 0.009). There is little evidence for association of alleles among the seven loci. Only one out of 21 pairwise comparisons demonstrated departures from independence (HLA-DQA1/HBGG, p = 0.008). The allelic frequency data generally are similar to that of U.S. Caucasians.  相似文献   
924.
925.
Short tandem repeat (STR) markers are commonly used in basic genetic research and in human identification testing. Clinically, STRs can be used to study genetic alterations in tumors. A genetic deletion common to many types of cancer is referred to as the loss of heterozygosity (LOH). Numerous examples of LOH in cancer have been described and some have been mapped to areas located in close proximity to markers employed in human identity testing. Despite this fact, LOH has rarely been observed for STR loci commonly employed in forensic testing. Recently, for medico-legal purposes, we were asked to determine whether a tissue biopsy originated from a particular individual. For a reference source we assessed two specimens, one from normal tissue and one from cancerous tissue. When both reference specimens were used to generate DNA profiles, we observed LOH at one STR locus, D13S317. As demonstrated in other cancers only the cancerous biopsy demonstrated LOH. The forensic community should be cognizant of these unusual circumstances because, as identification of human DNA continues to be used more extensively, certain instances will arise in which reference material will not be readily available. In these situations, archived specimens may be employed as a reference source. Clinical specimens such as tissue biopsies should be used with caution if they have not been confirmed to contain normal tissue.  相似文献   
926.
Three cases of suicide by electrocution with low-voltage current were observed in five years (1994-1998) by medical clinical forensic examiners of an Emergency Forensic Unit of the Paris suburb among 2,000 external death examinations. The cases involved one woman, aged 72 and two men, aged 38 and 41. In the last two cases, electric burns were retrieved under bared electric wires, placed on the arms or fingers in order to realize a hand-to-hand electric circuit involving the heart muscle. In the other case, the electric circuit between mouth and foot also involved the heart muscle. Household low-voltage current delivered (220 V in France) had a sufficient strength to induce local muscular paralysis and heart fibrillation. In the three cases, blood samples taken have retrieved very high levels of muscular enzymes (CPK, LDH) correlated to the mechanism of electric death. The rareness of suicide by electrocution and its forensic characteristics are detailed in order to help the clinical forensic examiners, prosecutors, and police officers concerned by such death examinations.  相似文献   
927.
The analysis of 35,312 cannabis preparations confiscated in the USA over a period of 18 years for delta-9-tetrahydrocannabinol (delta9-THC) and other major cannabinoids is reported. Samples were identified as cannabis, hashish, or hash oil. Cannabis samples were further subdivided into marijuana (loose material, kilobricks and buds), sinsemilla, Thai sticks and ditchweed. The data showed that more than 82% of all confiscated samples were in the marijuana category for every year except 1980 (61%) and 1981 (75%). The potency (concentration of delta9-THC) of marijuana samples rose from less than 1.5% in 1980 to approximately 3.3% in 1983 and 1984, then fluctuated around 3% till 1992. Since 1992, the potency of confiscated marijuana samples has continuously risen, going from 3.1% in 1992 to 4.2% in 1997. The average concentration of delta9-THC in all cannabis samples showed a gradual rise from 3% in 1991 to 4.47% in 1997. Hashish and hash oil, on the other hand, showed no specific potency trends. Other major cannabinoids [cannabidiol (CBD), cannabinol (CBN), and cannabichromene (CBC)] showed no significant change in their concentration over the years.  相似文献   
928.
Rapid developments in the area of biotechnology within the next decade are likely to have a significant impact on Canadian society. This article outlines the practical and ethical issues that will need to be addressed in the face of scientific advances, and contemplates the development of an appropriate policy framework in this regard. Surveying the approaches to policy development taken thus far, the author notes the underlying need for greater transparency and public participation. Rational and effective policies will only result from additional basic scientific data being made available to a more informed and engaged Canadian public.  相似文献   
929.
AB0 antigens can be extracted from human bone tissue into aqueous solution during boiling and then identified by absorption elution test.  相似文献   
930.
A protocol for comparative analysis of heroin making use of chromatographic methods and infra-red spectroscopy is presented.  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