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   211402篇
  免费   3387篇
  国内免费   87篇
耳鼻咽喉   1661篇
儿科学   8190篇
妇产科学   4163篇
基础医学   22140篇
口腔科学   2241篇
临床医学   16237篇
内科学   37735篇
皮肤病学   1341篇
神经病学   20010篇
特种医学   10092篇
外国民族医学   16篇
外科学   33175篇
综合类   2570篇
一般理论   22篇
预防医学   21127篇
眼科学   3397篇
药学   11336篇
中国医学   651篇
肿瘤学   18772篇
  2023年   251篇
  2022年   343篇
  2021年   728篇
  2020年   518篇
  2019年   756篇
  2018年   22641篇
  2017年   17978篇
  2016年   20192篇
  2015年   1712篇
  2014年   1877篇
  2013年   2244篇
  2012年   8986篇
  2011年   23008篇
  2010年   19830篇
  2009年   12530篇
  2008年   21212篇
  2007年   23519篇
  2006年   2342篇
  2005年   3903篇
  2004年   4902篇
  2003年   5787篇
  2002年   3844篇
  2001年   1251篇
  2000年   1383篇
  1999年   1007篇
  1998年   645篇
  1997年   545篇
  1996年   377篇
  1995年   359篇
  1994年   333篇
  1993年   272篇
  1992年   563篇
  1991年   639篇
  1990年   643篇
  1989年   520篇
  1988年   461篇
  1987年   470篇
  1986年   439篇
  1985年   445篇
  1984年   322篇
  1983年   254篇
  1982年   189篇
  1980年   197篇
  1979年   277篇
  1978年   202篇
  1977年   173篇
  1976年   184篇
  1975年   181篇
  1974年   224篇
  1973年   178篇
排序方式: 共有10000条查询结果,搜索用时 46 毫秒
21.
22.
Contraceptive use is an important strategy for the prevention of unwanted pregnancy and avoidance of induced abortion. Of all the contraception methods, emergency contraceptive (EC) offers the last chance to achieve this. However, few studies have documented the use of EC among young people in Ghana. This study explored knowledge and usage of EC as well as the factors associated with it among University of Cape Coast students. Data were obtained on the knowledge and usage of ECs among University of Cape Coast students in 2013. Logistic regression analysis was used to investigate the association between students’ socio-demographic characteristics and EC knowledge and use. More male students (72 %) than females (59 %) were sexually active. Fifty-seven percent of the respondents had ever heard of EC and 36 % had ever used EC. Although males were more likely to be sexually active, females were more likely to have knowledge of EC use compared to males. The study underscores the need to increase awareness regarding EC among University students in order to offer them the opportunity that EC provides if other forms of contraceptives are missed.  相似文献   
23.
24.
Gastroesophageal reflux is the most common benign disorder of the esophagus and laparoscopic Nissen fundoplication has become the standard surgical treatment for its treatment. In our area, where the use of bougie calibration is debatable, postoperative dysphagia is encountered often after this surgery although it is usually not permanent. The aim of this study was to investigate the effect of using a soft silicone tube 39 F in diameter for esophageal calibration during laparoscopic Nissen fundoplication on the incidence of postoperative dysphagia. We divided cases scheduled to undergo laparoscopic Nissen fundoplication between January 2009 and November 2010 into two groups, each consisting 25 patients. Esophageal calibration with a 39 F silicone orogastric tube was used for the first group while there was no operative calibration in the second group. The surgical duration was recorded; the presence and severity of the postoperative dysphagia was calculated by using a dysphagia severity scoring system during the 1-year postoperative follow-up. The dysphagia severity scores were significantly lower in group 1 than group 2 on the postoperative second day and at the end of the first week and first month. We did not find a significant difference at the end of the 6-month and first year. There was also no significant difference regarding surgery duration. The use of a soft orogastric tube 39 F in diameter for esophagus calibration during laparoscopic Nissen fundoplication has significantly decreased the incidence of postoperative transient dysphagia without affecting the duration of surgery. Although dysphagia gradually resolves in the majority of patients, a safe and easy calibration method for its prevention is worth developing, and we believe that the use of our method in larger series could be beneficial.  相似文献   
25.
Hawi  N.  von Falck  C.  Krettek  C.  Meller  R. 《Der Unfallchirurg》2019,122(12):944-949
Die Unfallchirurgie - Zur Diagnostik von Schultergelenkerkrankungen wird routinemäßig die Magnetresonanztomographie (MRT) durchgeführt. Diese kann entsprechend der klinischen...  相似文献   
26.
Batrachochytrium dendrobatidis is a fungal pathogen in the phylum Chytridiomycota that causes the skin disease chytridiomycosis. Chytridiomycosis is considered an emerging infectious disease linked to worldwide amphibian declines and extinctions. Although amphibians have well-developed immune defenses, clearance of this pathogen from the skin is often impaired. Previously, we showed that the adaptive immune system is involved in the control of the pathogen, but B. dendrobatidis releases factors that inhibit in vitro and in vivo lymphocyte responses and induce lymphocyte apoptosis. Little is known about the nature of the inhibitory factors released by this fungus. Here, we describe the isolation and characterization of three fungal metabolites produced by B. dendrobatidis but not by the closely related nonpathogenic chytrid Homolaphlyctis polyrhiza. These metabolites are methylthioadenosine (MTA), tryptophan, and an oxidized product of tryptophan, kynurenine (Kyn). Independently, both MTA and Kyn inhibit the survival and proliferation of amphibian lymphocytes and the Jurkat human T cell leukemia cell line. However, working together, they become effective at much lower concentrations. We hypothesize that B. dendrobatidis can adapt its metabolism to release products that alter the local environment in the skin to inhibit immunity and enhance the survival of the pathogen.  相似文献   
27.
28.
29.
30.
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