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   985篇
  免费   47篇
  国内免费   4篇
耳鼻咽喉   8篇
儿科学   44篇
妇产科学   11篇
基础医学   102篇
口腔科学   27篇
临床医学   118篇
内科学   261篇
皮肤病学   17篇
神经病学   31篇
特种医学   28篇
外科学   121篇
综合类   36篇
预防医学   66篇
眼科学   28篇
药学   92篇
中国医学   4篇
肿瘤学   42篇
  2023年   5篇
  2022年   18篇
  2021年   33篇
  2020年   13篇
  2019年   22篇
  2018年   25篇
  2017年   9篇
  2016年   16篇
  2015年   27篇
  2014年   36篇
  2013年   43篇
  2012年   35篇
  2011年   57篇
  2010年   28篇
  2009年   36篇
  2008年   48篇
  2007年   63篇
  2006年   55篇
  2005年   46篇
  2004年   60篇
  2003年   50篇
  2002年   48篇
  2001年   17篇
  2000年   20篇
  1999年   17篇
  1998年   13篇
  1997年   9篇
  1996年   5篇
  1995年   8篇
  1994年   6篇
  1993年   7篇
  1992年   16篇
  1991年   22篇
  1990年   13篇
  1989年   16篇
  1988年   11篇
  1987年   15篇
  1986年   11篇
  1985年   8篇
  1984年   7篇
  1983年   9篇
  1982年   2篇
  1981年   2篇
  1980年   2篇
  1978年   4篇
  1977年   4篇
  1976年   2篇
  1975年   3篇
  1974年   4篇
  1970年   3篇
排序方式: 共有1036条查询结果,搜索用时 15 毫秒
1.
Prenatal sonographic features of the rare anomaly of complete duplication of the urinary bladder and urethra are described in this case report. A coronal scan of the fetal pelvis at 29 weeks of gestation revealed two pyriform cystic structures. The umbilical arteries coursed around both of them. They emptied independently of each other. Postnatally the newborn had two vulvae, two anal openings, two bladders and two uteri.  相似文献   
2.
3.
4.
BACKGROUND: The effect of mitral valve morphology (MVM) on the long-term results of mitral balloon valvuloplasty (MBV) is not well established. The aim of the study was to evaluate the impact of MVM on long-term outcome of MBV. METHODS: Five hundred and eighteen consecutive patients (mean age, 31+/-11 years) who underwent successful MBV were followed up for 0.5-16.5 (mean, 6+/-4.5) years. Patients were divided into two groups according to their mitral echo score (MES) before MBV: group A (n=340; MES8). RESULTS: We report the immediate and long-term clinical and echocardiographic results of the above-mentioned 518 consecutive patients. The mitral valve area was significantly larger in group A than in group B, both immediately after MBV (2.0+/-0.3 vs. 1.82+/-0.3 cm2, respectively; P<0.0001) and also at the last follow-up (1.8+/-0.33 vs. 1.5+/-0.33 cm2, respectively; P<0.0001). Restenosis occurred in 38/340 (11%) in group A vs. 73/178 (41%) in group B (P<0.0001). Actuarial freedom from restenosis at 5, 10, 15 years were 92+/-2%, 85+/-3%, 65+/-6% for group A vs. 72+/-4%, 44+/-5%, 9+/-6% for group B (P<0.001). Event-free survival rates at 5, 10, 15 years for group A were 93+/-1%, 88+/-2%, 66+/-6% vs. 82+/-3%, 59+/-6%, 8+/-7% for group B (P<0.0001). Stepwise Cox multivariate regression analysis identified MES, preprocedure functional class, and postprocedure mitral valve area相似文献   
5.
6.
7.
A system was developed for exposure of unanesthetized mice to airborne chemicals and for continuous measurement of their breathing pattern prior to, during and following exposure. By measuring inspiratory and expiratory airflows (VI and VE), and integration with time to yield tidal volume (VT), we obtained characteristic modifications to the normal breathing pattern. These permitted recognition that a specific portion of the respiratory tract was affected by the selected airborne chemicals. Following recognition, we also quantitated the degree of effect using one specific measurement in each case. An effect on the upper respiratory tract, induced by the sensory irritant, 2-chlorobenzylchloride, was quantitated by measuring a decrease in respiratory frequency. An effect on the conducting airways, induced by the airway constrictor, carbamylcholine, was quantitated by a decrease in VE at the mid-point of VT. An effect at the alveolar level, induced either by the vagal nerve ending stimulant, propranolol, or by the pulmonary irritant, machining fluid G, was quantitated by an increase in the length of a pause induced at the end of expiration. The system is easy to construct and operate and can be used to rapidly evaluate the effects of airborne chemicals on the respiratory tract.  相似文献   
8.
The blood-brain permeabilities of L-[3H]tyrosine and the tyrosine hydroxylase (TH) inhibitor β-[14C]methyl-para-tyrosine ([14C]AMPT) were determined in rat striatum, a brain region rich in TH activity, and in other brain regions containing relatively little TH activity. In striatum, the unidirectional clearance rate (K1) for L-[3H]tyrosine (6.2 ml hg- ?1 min?1) was significantly greater than the rates for L-[14C]AMPT (2.8 ml hg?1 min?1) and D-[14C]AMPT (0.8 ml hg?1 min?1). The apparent volume of distribution (Vf) for L-[14C]AMPT in striatum (72.5 ± 4.0 ml hg-1) did not differ from the Vf in other brain regions. The homogeneous distribution of L-[14C]AMPT in rat brain indicates that labeled AMPT is unsuitable for the study of TH in vivo by quantitative autoradiography. © 1994 Wiley-Liss, Inc.  相似文献   
9.
10.
Eighty-five young Mauritian Indians, male survivors of premature myocardial infarction (MI) and thus belonging to a high risk group, were compared with 108 stringently selected controls for a possible association between premature MI and an insertion/deletion (I/D) polymorphism in the gene encoding angiotensin I-converting enzyme (ACE). The frequency of the D allele was 0.42 in the MI group and 0.43 in the control group, and thus no association between I/D polymorphism of ACE with susceptibility to early-onset MI was found in this population group. Other gene components of the renin-angiotensin system and lipid metabolism need to be explored to understand the genetic factors involved in causing MI at an early age.  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