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   83752篇
  免费   4438篇
  国内免费   197篇
耳鼻咽喉   1054篇
儿科学   1900篇
妇产科学   1711篇
基础医学   11494篇
口腔科学   3378篇
临床医学   6388篇
内科学   20176篇
皮肤病学   1956篇
神经病学   7508篇
特种医学   1912篇
外国民族医学   2篇
外科学   11197篇
综合类   350篇
一般理论   33篇
预防医学   7355篇
眼科学   1617篇
药学   5477篇
中国医学   310篇
肿瘤学   4569篇
  2023年   551篇
  2022年   353篇
  2021年   1405篇
  2020年   864篇
  2019年   1445篇
  2018年   2616篇
  2017年   1585篇
  2016年   1702篇
  2015年   2380篇
  2014年   2481篇
  2013年   3642篇
  2012年   7090篇
  2011年   7178篇
  2010年   3252篇
  2009年   2423篇
  2008年   6140篇
  2007年   6264篇
  2006年   6311篇
  2005年   5978篇
  2004年   5485篇
  2003年   4932篇
  2002年   4708篇
  2001年   1834篇
  2000年   2338篇
  1999年   1218篇
  1998年   281篇
  1997年   193篇
  1996年   202篇
  1995年   171篇
  1994年   143篇
  1993年   138篇
  1992年   243篇
  1991年   221篇
  1990年   184篇
  1989年   152篇
  1988年   137篇
  1987年   125篇
  1986年   148篇
  1985年   152篇
  1984年   150篇
  1983年   114篇
  1982年   121篇
  1981年   99篇
  1980年   104篇
  1979年   86篇
  1978年   71篇
  1977年   63篇
  1976年   66篇
  1974年   65篇
  1973年   65篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
11.
12.
13.
The influence of left ventricular volume variations and regurgitant fraction variations upon left ventricular ejection fraction, during exercise was examined using equilibrium radionuclide angiography in patients suffering from aortic regurgitation. Ejection fraction (EF), regurgitant fraction (RF), end diastolic volume (EDV) and end systolic volume (ESV) variations from rest to peak exercise were determined in 44 patients suffering from chronic aortic regurgitation (AR) and in 8 healthy volunteers (C). In C, EF increased (+0.10±0.03, P<0.01) and ESV decreased significantly (-23%±12%, P<0.01) RF and EDV did not vary significantly. In AR patients, EF, EDV and ESV did not vary significantly because of important scattering of individual values. Changes in EF and ESV were inversely correlated (r=-0.79, P<0.01) and RF decreased significantly (-0.12±0.10, P<0.01). Volumes and EF changes during exercise occurred in three different ways. In a 1st subgroup of 7 patients, EF increased (+0.09±0.03, P<0.05) in conjunction with a reduction of ESV (-24%±12%, P<0.05) without a significant change in EDV. In a 2nd group of 22 patients. EF decreased (-0.04±0.07, P<0.01) in association with an increase in ESV (+17%±16%, P<0.01) and no change in EDV. In a 3rd subgroup of 15 patients, EF decreased (-0.02±0.06, P<0.01) despite a reduction in ESV (-7%±6%, P<0.01) because of a dramatic EDV decrease (-10%±6%, P<0.05). In this subgroup, changes in EF were inversely correlated with changes in ESV (r=-0.55, P<0.01) and positively related to EDV variations (r=0.42, P=0.02). EDV related to EDV variations (r=0.42, P=0.02). EDV changes were weakly, but significantly, correlated to RF decrease (r=0.39, P<0.05). We conclude that changes in left ventricular ejection fraction during exercise in patients with chronic aortic regurgitation are significantly related in some patients to changes in ventricular loading conditions as well as contractile state. Therefore, a correct interpretation of EF changes during exercise requires the simultaneous determination of changes in LV volumes.Abbreviations EDV end diastolic volume - EF ejection fraction - ESV end systolic volume - LV left ventricle - RV right ventricle  相似文献   
14.
A case of testicular cancer in 2 brothers is reported and a review of the literature about testicular malignancies and etiologic factors in closely related family members is given. The familial incidence of testicular tumor is found to be 3% in twins and 0.6-2.1% in less closely related men. Tumors were of the same histology in 70-77% of the twins, whereas in brothers and in other degrees of relationship tumors of different histology mostly occur. Following the diagnosis of the tumor in the first man, the average interval to presentation of the tumor in the relative was 3.7 years in twins, 7.7 years in nontwin brothers and 13.5 years for less closely related men. The need for a thorough checkup of other family members is advised.  相似文献   
15.
16.
17.
18.
L1 disease is the most common genetic cause of congenital hydrocephalus. Mutations in the L1CAM gene are associated with an overlapping clinical spectrum of four X-linked neurological conditions, characterized by hydrocephalus, mental retardation, lower limb spasticity and adducted thumbs. Brain anomalies are frequently present in L1 disease. We describe these anomalies by reporting a case of a male newborn presenting with congenital hydrocephalus along with corpus callosum agenesis and enlargement of the massa intermedia. These findings, in association with the presence of clasped thumbs, raised the suspicion of L1 disease, which was confirmed by the detection of a mutation in the L1CAM gene. In cases of congenital hydrocephalus, recognition of the brain anomalies associated with L1 disease may contribute to pursuing the genetic analysis needed for the diagnosis and genetic counseling.  相似文献   
19.
20.
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