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   680篇
  免费   22篇
  国内免费   4篇
耳鼻咽喉   2篇
儿科学   3篇
妇产科学   39篇
基础医学   165篇
口腔科学   16篇
临床医学   51篇
内科学   135篇
皮肤病学   4篇
神经病学   34篇
特种医学   3篇
外科学   125篇
综合类   1篇
预防医学   41篇
眼科学   14篇
药学   34篇
中国医学   2篇
肿瘤学   37篇
  2022年   14篇
  2021年   33篇
  2020年   13篇
  2019年   16篇
  2018年   15篇
  2017年   14篇
  2016年   25篇
  2015年   16篇
  2014年   25篇
  2013年   18篇
  2012年   54篇
  2011年   58篇
  2010年   26篇
  2009年   18篇
  2008年   21篇
  2007年   35篇
  2006年   19篇
  2005年   15篇
  2004年   20篇
  2003年   20篇
  2002年   14篇
  2000年   7篇
  1999年   6篇
  1998年   3篇
  1997年   2篇
  1992年   9篇
  1991年   20篇
  1990年   21篇
  1989年   21篇
  1988年   28篇
  1987年   20篇
  1986年   12篇
  1985年   14篇
  1984年   5篇
  1983年   5篇
  1981年   2篇
  1980年   2篇
  1979年   7篇
  1978年   3篇
  1976年   1篇
  1975年   2篇
  1974年   2篇
  1973年   2篇
  1972年   2篇
  1971年   2篇
  1970年   2篇
  1969年   6篇
  1968年   2篇
  1967年   2篇
  1966年   2篇
排序方式: 共有706条查询结果,搜索用时 15 毫秒
1.
The ability of 12 new thiazole derivatives to influence the muscle contractility mediated by purine P2X receptors has been studied in vitro using isolated tissues of rats and guinea pigs. Most of the synthesized compounds did not cause significant effects, but two compounds exhibited pronounced antagonism with respect to P2X-mediated contractility response. These compounds offer a good starting point for the synthesis of new effective antagonists of P2 receptors. __________ Translated from Khimiko-Farmatsevticheskii Zhurnal, Vol. 39, No. 6, pp. 22 – 25, June, 2005.  相似文献   
2.
3.
4.
Technology is a prominent way that young children choose to play. With new advents in technology, children are finding it easier to gain access to technology through parents’ cell phones and tablets. The influx of technology in the daily lives of children is putting into question whether or not children are spending too much time engaging in such play. In the current study, data were collected on how 3–5-year-old children played on a typical weekday and weekend. Of the weekday activities, parents (n?=?31) reported 53.00 hours of technology play for an average of 1.71 hours per child per day. There was an increased amount of time spent on non-technology activities listed by parents for a total of 59.25 hours and an average of 1.91 hours per child. A smaller number of parents (n?=?14) recorded outdoor play, totalling 17.50 hours with an average of 1.25 hours per child.  相似文献   
5.
6.
7.
The proportion of new HIV diagnoses between May and December 2009 across Odessa recently-infected was estimated using the BED-CEIA assay. Logistic regression models were used to explore factors associated with testing as recent. Of 1,313 newly-diagnosed individuals, 321 (24 %) were classified as recent. Recent infection was less likely among older adults [odds ratio (OR) = 0.70 per 10-year increase, 95 % CI 0.60–0.82]. Compared to men residing in Odessa city, women in rural Odessa and non-resident men were more likely to be recently-infected (OR 1.85, 1.26–2.71 and 2.83, 1.15–6.97, respectively). Reason for test was not associated with recent infection. In sensitivity analysis, after excluding individuals tested due to clinical indications, the proportion recently-infected and the association with age remained virtually unchanged. Our findings suggest a high risk of onward transmission, particularly in younger age groups. These findings highlight the need for tailored prevention strategies and ongoing RITA testing to monitor and evaluate effectiveness of prevention programmes.  相似文献   
8.
9.
The adaptive immune system relies on rare cognate lymphocytes to detect pathogen-derived antigens. Na?ve lymphocytes recirculate through secondary lymphoid organs in search of cognate antigen. Here, we show that the na?ve-lymphocyte recirculation pattern is controlled at the level of innate immune recognition, independent of antigen-specific stimulation. We demonstrate that inflammation-induced lymphocyte recruitment to the lymph node is mediated by the remodeling of the primary feed arteriole, and that its physiological role is to increase the efficiency of screening for rare antigen-specific lymphocytes. Our data reveal a mechanism of innate control of adaptive immunity: by increasing the pool of na?ve lymphocytes for detection of foreign antigens via regulation of vascular input to the local lymph node.  相似文献   
10.
Objective: To investigate risk factors for postpartum hemorrhage (PPH) in vaginal deliveries and the influence of previous PPH on the subsequent pregnancy.

Study design: A retrospective cohort study including first singleton deliveries between the years 1988 and 2012 was performed comparing deliveries with and without PPH. In addition, perinatal outcomes of the subsequent pregnancy were evaluated. Multivariable analysis was performed to control for confounders.

Results: PPH complicated 0.8% of all first vaginal deliveries. Significant risk factors for PPH in vaginal delivery, using a multiple logistic regression model, were: post-term pregnancy, fertility treatments, hypertensive disorders, labor dystocia during the 2nd, and perineal tears grade 2 and 3, respectively. Previous PPH was found to be an independent risk factor for PPH in the subsequent pregnancy. Moreover, previous PPH was found to be a significant risk factor for cesarean section (CS) deliver, to complicate delivery with revision of uterus cavity, anemia, and to require blood transfusion.

Conclusion: Previous PPH poses a risk for recurrent PPH in subsequent delivery and an increased risk for CS. As PPH remains one of the major causes of maternal morbidity, this study strengthens the need for a comprehensive evaluation of prior PPH as a major risk factor for PPH recurrence.  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