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   1396438篇
  免费   99887篇
  国内免费   2323篇
耳鼻咽喉   20000篇
儿科学   46006篇
妇产科学   40515篇
基础医学   203688篇
口腔科学   39600篇
临床医学   115947篇
内科学   280802篇
皮肤病学   30494篇
神经病学   109230篇
特种医学   52716篇
外国民族医学   367篇
外科学   211683篇
综合类   27110篇
现状与发展   1篇
一般理论   340篇
预防医学   104650篇
眼科学   31833篇
药学   106328篇
  1篇
中国医学   3039篇
肿瘤学   74298篇
  2019年   11054篇
  2018年   16621篇
  2017年   11761篇
  2016年   12798篇
  2015年   14688篇
  2014年   19564篇
  2013年   29663篇
  2012年   42555篇
  2011年   45608篇
  2010年   26125篇
  2009年   23515篇
  2008年   42605篇
  2007年   46048篇
  2006年   45973篇
  2005年   45100篇
  2004年   42760篇
  2003年   41322篇
  2002年   40527篇
  2001年   61153篇
  2000年   63145篇
  1999年   53324篇
  1998年   14733篇
  1997年   13164篇
  1996年   13366篇
  1995年   12570篇
  1994年   11933篇
  1992年   42034篇
  1991年   41205篇
  1990年   40657篇
  1989年   39325篇
  1988年   36655篇
  1987年   35868篇
  1986年   34263篇
  1985年   32570篇
  1984年   24238篇
  1983年   21066篇
  1982年   12503篇
  1981年   11044篇
  1979年   22935篇
  1978年   16067篇
  1977年   13913篇
  1976年   13156篇
  1975年   14442篇
  1974年   16961篇
  1973年   16387篇
  1972年   15576篇
  1971年   14511篇
  1970年   13473篇
  1969年   13003篇
  1968年   12225篇
排序方式: 共有10000条查询结果,搜索用时 211 毫秒
41.
42.
43.
44.
45.
46.
47.
Preimplantation genetic diagnosis (PGD) was originally developed to diagnose embryo-related genetic abnormalities for couples who present a high risk of a specific inherited disorder. Because this technology involves embryo selection, the medical, bioethical, and legal implications of the technique have been debated, particularly when it is used to select features that are not related to serious diseases. Although several initiatives have attempted to achieve regulatory harmonization, the diversity of healthcare services available and the presence of cultural differences have hampered attempts to achieve this goal. Thus, in different countries, the provision of PGD and regulatory frameworks reflect the perceptions of scientific groups, legislators, and society regarding this technology. In Brazil, several texts have been analyzed by the National Congress to regulate the use of assisted reproduction technologies. Legislative debates, however, are not conclusive, and limited information has been published on how PGD is specifically regulated. The country requires the development of new regulatory standards to ensure adequate access to this technology and to guarantee its safe practice. This study examined official documents published on PGD regulation in Brazil and demonstrated how little direct oversight of PGD currently exists. It provides relevant information to encourage reflection on a particular regulation model in a Brazilian context, and should serve as part of the basis to enable further reform of the clinical practice of PGD in the country.  相似文献   
48.
The present study aimed at measuring seropositivities for infection by Ascaris suum and Toxocara canis using the excretory/secretory (E/S) antigens from Ascaris suum (AES) and Toxocara canis (TES) within an indigenous population. In addition, quantification of cytokine expressions in peripheral blood cells was determined. A total of 50 Warao indigenous were included; of which 43 were adults and seven children. In adults, 44.1% were seropositive for both parasites; whereas children had only seropositivity to one or the other helminth. For ascariosis, the percentage of AES seropositivity in adults and children was high; 23.3% and 57.1%, respectively. While that for toxocariosis, the percentage of TES seropositivity in adults and children was low; 9.3% and 14.3%, respectively. The percentage of seronegativity was comparable for AES and TES antigens in adults (27.9%) and children (28.6%). When positive sera were analyzed by Western blotting technique using AES antigens; three bands of 97.2, 193.6 and 200.2 kDas were mostly recognized. When the TES antigens were used, nine major bands were mostly identified; 47.4, 52.2, 84.9, 98.2, 119.1, 131.3, 175.6, 184.4 and 193.6 kDas. Stool examinations showed that Blastocystis hominis, Hymenolepis nana and Entamoeba coli were the most commonly observed intestinal parasites. Quantification of cytokines IFN-γ, IL-2, IL-6, TGF-β, TNF-α, IL-10 and IL-4 expressions showed that there was only a significant increased expression of IL-4 in indigenous with TES seropositivity (p < 0.002). Ascaris and Toxocara seropositivity was prevalent among Warao indigenous.  相似文献   
49.
50.
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