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   1696128篇
  免费   123348篇
  国内免费   3781篇
耳鼻咽喉   21731篇
儿科学   55635篇
妇产科学   46152篇
基础医学   241283篇
口腔科学   48743篇
临床医学   151313篇
内科学   333611篇
皮肤病学   38652篇
神经病学   131138篇
特种医学   63890篇
外国民族医学   242篇
外科学   257305篇
综合类   38947篇
现状与发展   4篇
一般理论   531篇
预防医学   124242篇
眼科学   40211篇
药学   123630篇
  7篇
中国医学   4475篇
肿瘤学   101515篇
  2021年   12792篇
  2019年   13527篇
  2018年   19950篇
  2017年   15216篇
  2016年   16619篇
  2015年   18960篇
  2014年   26214篇
  2013年   37953篇
  2012年   52735篇
  2011年   55436篇
  2010年   32775篇
  2009年   30710篇
  2008年   51539篇
  2007年   54821篇
  2006年   55290篇
  2005年   52584篇
  2004年   50789篇
  2003年   48205篇
  2002年   46424篇
  2001年   91795篇
  2000年   93625篇
  1999年   76977篇
  1998年   19736篇
  1997年   17282篇
  1996年   17406篇
  1995年   16756篇
  1994年   15298篇
  1993年   14081篇
  1992年   57391篇
  1991年   55281篇
  1990年   52976篇
  1989年   50752篇
  1988年   46133篇
  1987年   44938篇
  1986年   42235篇
  1985年   39987篇
  1984年   29351篇
  1983年   24908篇
  1982年   13898篇
  1979年   25530篇
  1978年   17574篇
  1977年   14906篇
  1976年   13874篇
  1975年   14563篇
  1974年   17631篇
  1973年   16944篇
  1972年   15673篇
  1971年   14453篇
  1970年   13431篇
  1969年   12518篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
961.
962.
AIM: The present meta-analysis aims to compare short-term and long-term outcomes in patients undergoing laparoscopic or open subtotal colectomy for benign and malignant disease. METHODS: A literature search of Medline, Ovid, Embase and Cochrane databases was performed to identify studies published between 1992 and 2005, comparing laparoscopic (LSC) and open (OSC) subtotal colectomy. A random effect meta-analytical technique was used and sensitivity analysis performed on studies published since the beginning of 2000, higher quality papers, those reporting on more than 40 patients, and those studies reporting on adult cases or acute colitis. RESULTS: A total of eight studies satisfied the criteria for inclusion. These included outcomes on 336 patients, 143 (42.6%) of whom had undergone laparoscopic resection, with an overall conversion rate to open surgery of 5% (range 0-11.8%). Operative time was significantly longer in the laparoscopic group by 86.2 min (P < 0.001) and throughout subgroup analysis, although it was only in patients with acute colitis that this finding was without significant heterogeneity. Operative blood loss was less in the laparoscopic group by 57.5 millilitres in high quality and studies published since 2000, and 65.3 millilitres in those reporting on more than 40 patients. There was no significant difference in early or long-term complications between the groups. A statistically significant reduction in length of postoperative stay was observed in the laparoscopic groups by 2.9 days (P < 0.001). CONCLUSION: Laparoscopic subtotal colectomy was associated with longer operating times but a reduced length of stay compared to open surgery. Although short-term outcomes were equivalent in both groups, the suggested benefits in terms of reduced long-term obstructive complications were not supported by this meta-analysis.  相似文献   
963.
BACKGROUND: Stress can aggravate the allergic inflammation, but determinants of disturbed immune regulation are largely unknown. OBJECTIVE: To determine systemic immunological, local inflammatory and functional airway responses to stress in healthy and atopic individuals. METHODS: Forty-one undergraduate students, 22 with allergy of whom 16 had asthma, and 19 healthy controls, were studied in a low-stress period and in association with a large exam. Subjects completed questionnaires on stress and health behaviours, underwent lung function tests, bronchial methacholine challenge, measurements of exhaled nitric oxide and urine cortisol. Blood cells were phenotyped, and cytokines from mononuclear blood cells were analysed. RESULTS: Perceived stress and anxiety increased in both groups during the exam period while cortisol increased only in the atopy group. Cytokine production decreased broadly in response to stress in both groups, which was paralleled by an increase in the proportion of regulatory T cells (CD4(+)CD45RO(+)CD25(bright)). Interestingly, atopic individuals, but not controls, reacted with a decreased T-helper type 1/T-helper type 2 (Th1/Th2) ratio and a decrease in natural killer (NK) cell numbers in response to stress. In control subjects only, exhaled nitric oxide decreased and forced expiratory volume in one second increased during stress. CONCLUSION: Atopic and non-atopic subjects shared some immune changes in response to stress, such as a dramatic decline in cytokines and an increase in the number of regulatory T cells in peripheral blood. However, other stress-induced immune changes were unique to atopic individuals, such as a skewed Th1/Th2 ratio and reduced NK cell numbers, indicating that some pathogenic mechanisms in atopics may be more strongly affected by stress than others.  相似文献   
964.
965.
966.
967.
968.
969.
970.
The inhibitory effect of polysaccharide on mumps virus multiplication   总被引:12,自引:12,他引:0  
Polysaccharides derived from type-specific Friedl?nder bacilli cause inhibition of the multiplication of mumps virus in the allantoic sac of the chick embryo. As little as 5 microg. of polysaccharide is effective as an inhibitor. Inhibition of multiplication is obtained when polysaccharide is injected as long as 4 days after inoculation of virus. Chemical studies have shown that the structural configurations of the polysaccharide responsible for specific serological activity are not identical with those which determine the inhibitory effect relative to mumps virus. The possible mechanisms of the inhibition of viral multiplication by means of polysaccharides are discussed.  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