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   31218篇
  免费   5686篇
  国内免费   365篇
耳鼻咽喉   817篇
儿科学   1145篇
妇产科学   632篇
基础医学   2812篇
口腔科学   817篇
临床医学   4416篇
内科学   7288篇
皮肤病学   772篇
神经病学   2702篇
特种医学   1332篇
外科学   6719篇
综合类   527篇
现状与发展   2篇
一般理论   18篇
预防医学   2816篇
眼科学   648篇
药学   1652篇
中国医学   6篇
肿瘤学   2148篇
  2023年   674篇
  2022年   245篇
  2021年   555篇
  2020年   970篇
  2019年   460篇
  2018年   1009篇
  2017年   969篇
  2016年   1103篇
  2015年   1025篇
  2014年   1489篇
  2013年   1777篇
  2012年   1110篇
  2011年   1096篇
  2010年   1194篇
  2009年   1478篇
  2008年   1126篇
  2007年   1035篇
  2006年   1104篇
  2005年   973篇
  2004年   863篇
  2003年   881篇
  2002年   841篇
  2001年   872篇
  2000年   810篇
  1999年   835篇
  1998年   622篇
  1997年   600篇
  1996年   707篇
  1995年   625篇
  1994年   513篇
  1993年   398篇
  1992年   662篇
  1991年   635篇
  1990年   540篇
  1989年   566篇
  1988年   510篇
  1987年   461篇
  1986年   466篇
  1985年   500篇
  1984年   403篇
  1983年   333篇
  1982年   287篇
  1981年   267篇
  1980年   240篇
  1979年   297篇
  1978年   260篇
  1977年   275篇
  1975年   234篇
  1974年   251篇
  1973年   252篇
排序方式: 共有10000条查询结果,搜索用时 475 毫秒
991.
This study examined HIV and hepatitis risk behaviours among anabolic-androgenic steroid (AAS) users and controls, providing a detailed assessment of both injection and sexual practices. Fifty AAS-using and 40 non-AAS-using weight trainers completed a semi-structured interview followed by a detailed questionnaire. The 'high risk' behaviour of sharing needles and syringes was not current practice among the AAS-using sample, with only one user reporting sharing injecting equipment in the past. However, for some users it was common practice to share multi-dose vials (19%) and to divide drugs using syringes (17%). Both these practices are potential routes for HIV and hepatitis infection. Significantly more AAS users (36%) reported increases in sex drive over the last three months than did the control subjects (5%). More AAS users than controls were engaging in sex with more than one partner while infrequently using condoms. These findings support the maintenance of needle exchange schemes which are essential to continued safe injecting practices among AAS users. The elevated sexual risk behaviour of AAS users could be due to AAS's effect of increasing sex drive or to a 'risk taking' personality trait among AAS users.  相似文献   
992.
993.
994.
995.
996.
997.
The fission yeast telomerase RNA (TER1) precursor harbors an intron immediately downstream from its mature 3′ end. Unlike most introns, which are removed from precursor RNAs by the spliceosome in two sequential but tightly coupled transesterification reactions, TER1 only undergoes the first cleavage reaction during telomerase RNA maturation. The mechanism underlying spliceosome-mediated 3′ end processing has remained unclear. We now demonstrate that a strong branch site (BS), a long distance to the 3′ splice site (3′ SS), and a weak polypyrimidine (Py) tract act synergistically to attenuate the transition from the first to the second step of splicing. The observation that a strong BS antagonizes the second step of splicing in the context of TER1 suggests that the BS–U2 snRNA interaction is disrupted after the first step and thus much earlier than previously thought. The slow transition from first to second step triggers the Prp22 DExD/H-box helicase-dependent rejection of the cleaved products and Prp43-dependent “discard” of the splicing intermediates. Our findings explain how the spliceosome can function in 3′ end processing and provide new insights into the mechanism of splicing.  相似文献   
998.
Hereditary hemochromatosis (HH) is a common preventable disorder of iron overload that can result in liver cirrhosis and reduced lifespan. Most HH is due to homozygosity for the HFE p.C282Y substitution. We conducted a study of screening for p.C282Y in high schools where p.C282Y heterozygotes (CY) individuals were informed of their genotype by letter. We studied whether these individuals understood the implications of their genotype, whether this resulted in anxiety or reduced health perception and whether cascade testing was higher in families of CY than wild‐type homozygous (CC) individuals. We found 586 of 5757 (1 in 10) screened individuals were CY. One month after receiving their result, 83% correctly answered that they have one copy of p.C282Y. There was no adverse change in anxiety or health perception from prior to screening to 1 month after receiving results. Significantly more family members of CY individuals than CC individuals were informed about HH and had testing for HH. In conclusion, we found that informing CY individuals of their genotype does not increase anxiety and the implications are generally well understood. This leads to cascade testing in a minority of families. CY individuals should be informed of their genetic status when identified by population screening.  相似文献   
999.
1000.
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