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   5749篇
  免费   120篇
各国政治   238篇
工人农民   226篇
世界政治   456篇
外交国际关系   209篇
法律   3595篇
中国政治   49篇
政治理论   1079篇
综合类   17篇
  2021年   40篇
  2020年   69篇
  2019年   104篇
  2018年   131篇
  2017年   115篇
  2016年   120篇
  2015年   69篇
  2014年   118篇
  2013年   583篇
  2012年   142篇
  2011年   151篇
  2010年   123篇
  2009年   139篇
  2008年   171篇
  2007年   156篇
  2006年   140篇
  2005年   131篇
  2004年   155篇
  2003年   124篇
  2002年   100篇
  2001年   310篇
  2000年   277篇
  1999年   194篇
  1998年   79篇
  1997年   79篇
  1996年   53篇
  1995年   54篇
  1994年   48篇
  1993年   38篇
  1992年   121篇
  1991年   139篇
  1990年   131篇
  1989年   126篇
  1988年   113篇
  1987年   126篇
  1986年   100篇
  1985年   96篇
  1984年   96篇
  1983年   83篇
  1982年   57篇
  1981年   73篇
  1980年   34篇
  1979年   74篇
  1978年   43篇
  1975年   37篇
  1974年   49篇
  1973年   54篇
  1972年   39篇
  1971年   34篇
  1970年   29篇
排序方式: 共有5869条查询结果,搜索用时 15 毫秒
821.
822.
823.
824.
825.
826.
827.
POPULATIONS: This study reports the genetic polymorphism observed at 15 short tandem repeat loci D3S1358, TH01, D21S11, D18S51, D5S818, D13S317, D7S820, D16S539, CSF1PO, vWA, D8S1179, TPOX, D2S1338, D19S433, and FGA in four aboriginal populations of Bengal. The analysis was performed to decipher the suitability of CODIS as well as six other highly polymorphic and unlinked markers in Forensic Testing. Studied populations include four tribes: Karmali, Kora, Maheli, and Lodha.  相似文献   
828.
Utilizing a database of standards for forensic casework is a valuable resource. Undoubtedly, as more standards (and corresponding information about the specimens) are collected, there is a greater certainty of identification when a questioned and a known item cannot be distinguished after a series of analyses. The United States Secret Service and the Internal Revenue Service National Forensic Laboratory jointly maintain the largest known forensic collection of writing inks in the world, which is comprised of over 8500 ink standards collected worldwide, dating back to the 1920s. This study was conducted to evaluate the reliability of matching arbitrarily purchased pens with known inks from a database. One hundred pens were randomly obtained from a variety of sources and their respective ink compositions were compared with standards. Eighty-five of the inks were determined to be suitable for comparison utilizing optical examinations and thin-layer chromatography. Three of the inks did not match any of the specimens on record; one of these inks was similar to an ink from an identical brand of pen that was in the database, but had a modified formulation.  相似文献   
829.
The population of the Asian elephant is being dramatically reduced due to poaching of the ivory from the male. As poaching occurs in remote forests, it often takes weeks or longer for it to be discovered and it is therefore often very difficult to determine the sex of the decomposed body. Data suggest that in the recent past, over 2000 male elephants have been poached in South India. We have developed a technique based on molecular markers to determine that the carcass is an elephant and that it is a male. Using DNA sequence information from Genbank, we have developed two primer pairs: one for the mitochondrial DNA (mtDNA) and the other for the sex-determining region of Y chromosome (SRY) gene of the Indian elephant. After PCR amplification of known elephant DNA, we found that the mtDNA was common in both males and females, whereas the SRY-specific amplicon was observed only in the male.  相似文献   
830.
Bromethalin is a neurotoxin found in some rodenticides. A delusional 21-year-old male presented to a hospital with altered mental status the day after ingesting a bromethalin-based rodenticide. He died 7 days after his self-reported exposure to c. 17 mg bromethalin (equivalent to 0.33 mg bromethalin/kg). His clinicopathologic course was characterized by altered mental status, obtundation, increased cerebrospinal fluid pressure, cerebral edema, death, and diffuse histologic vacuolization of the white matter in the central nervous system seen on microscopic examination at autopsy. The presence of a demethylated form of bromethalin in the patient's liver and brain was confirmed by gas chromatography with mass spectrometry. Clinical signs and lesions observed in this patient are similar to those seen in animals poisoned with bromethalin. This case illustrates the potential for bromethalin ingestion to result in fatal human poisoning.  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