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   209659篇
  免费   3022篇
  国内免费   201篇
耳鼻咽喉   1527篇
儿科学   7667篇
妇产科学   3915篇
基础医学   19892篇
口腔科学   2720篇
临床医学   15386篇
内科学   38193篇
皮肤病学   1318篇
神经病学   18429篇
特种医学   10096篇
外国民族医学   4篇
外科学   35105篇
综合类   3138篇
现状与发展   3篇
一般理论   27篇
预防医学   20372篇
眼科学   4038篇
药学   12145篇
  1篇
中国医学   892篇
肿瘤学   18014篇
  2023年   416篇
  2022年   1065篇
  2021年   1655篇
  2020年   989篇
  2019年   1271篇
  2018年   23211篇
  2017年   18289篇
  2016年   20501篇
  2015年   2185篇
  2014年   2442篇
  2013年   2757篇
  2012年   9898篇
  2011年   23720篇
  2010年   20297篇
  2009年   12806篇
  2008年   21450篇
  2007年   23662篇
  2006年   2478篇
  2005年   3865篇
  2004年   4893篇
  2003年   5597篇
  2002年   3580篇
  2001年   617篇
  2000年   700篇
  1999年   430篇
  1998年   388篇
  1997年   326篇
  1996年   224篇
  1995年   202篇
  1994年   187篇
  1993年   132篇
  1992年   181篇
  1991年   241篇
  1990年   248篇
  1989年   196篇
  1988年   154篇
  1987年   134篇
  1986年   109篇
  1985年   144篇
  1984年   95篇
  1983年   72篇
  1982年   77篇
  1981年   55篇
  1980年   80篇
  1979年   52篇
  1978年   48篇
  1974年   55篇
  1938年   63篇
  1932年   57篇
  1930年   48篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
21.
International Urology and Nephrology - To report current results of complete penile disassembly technique in epispadias repair. In ten years, we have preformed 31 complete penile disassembly for...  相似文献   
22.
To determine the protective effect of aloe-emodin (AE) from high glucose induced toxicity in RIN-5F (pancreatic β-cell) cell and restoration of its function was analyzed. RIN-5F cells have been cultured in high glucose (25 mM glucose) condition, with and without AE treatment. RIN-5F cells cultured in high glucose decreased cell viability and increased ROS levels after 48 hr compared with standard medium (5.5 mM glucose). Glucotoxicity was confirmed by significantly increased ROS production, increased pro-inflammatory (IFN-γ, IL-1β,) & decreased anti-inflammatory (IL-6&IL-10) cytokine levels, increased DNA fragmentation. In addition, we found increased Bax, caspase 3, Fadd, and Fas and significantly reduced Bcl-2 expression after 48 hr. RIN-5F treated with both high glucose and AE (20 μM) decreased ROS generation and prevent RIN-5F cell from glucotoxicity. In addition, AE treated cells cultured in high glucose were transferred to standard medium, normal responsiveness to glucose was restored within 8hr and normal basal insulin release within 24 hr was achieved when compared to high glucose.  相似文献   
23.
24.
25.
Dehydrogenase activity is frequently used to assess the general condition of microorganisms in soil and activated sludge. Many studies have investigated the inhibition of dehydrogenase activity by various compounds, including heavy metal ions. However, the time after which the measurements are carried out is often chosen arbitrarily. Thus, it can be difficult to estimate how the toxic effects of compounds vary during the reaction and when the maximum of the effect would be reached. Hence, the aim of this study was to create simple and useful mathematical model describing changes in dehydrogenase activity during exposure to substances that inactivate enzymes. Our model is based on the Lagergrens pseudo-first-order equation, the rate of chemical reactions, enzyme activity, and inactivation and was created to describe short-term changes in dehydrogenase activity. The main assumption of our model is that toxic substances cause irreversible inactivation of enzyme units. The model is able to predict the maximum direct toxic effect (MDTE) and the time to reach this maximum (TMDTE). In order to validate our model, we present two examples: inactivation of dehydrogenase in microorganisms in soil and activated sludge. The model was applied successfully for cadmium and copper ions. Our results indicate that the predicted MDTE and TMDTE are more appropriate than EC50 and IC50 for toxicity assessments, except for long exposure times.  相似文献   
26.
27.
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   
28.
29.
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   
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