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   298696篇
  免费   17327篇
  国内免费   421篇
耳鼻咽喉   4247篇
儿科学   10335篇
妇产科学   10275篇
基础医学   45307篇
口腔科学   7699篇
临床医学   24355篇
内科学   56357篇
皮肤病学   6404篇
神经病学   21170篇
特种医学   11657篇
外国民族医学   43篇
外科学   46899篇
综合类   7779篇
现状与发展   1篇
一般理论   162篇
预防医学   20243篇
眼科学   6978篇
药学   21064篇
中国医学   803篇
肿瘤学   14666篇
  2019年   2331篇
  2018年   3725篇
  2017年   2709篇
  2016年   3133篇
  2015年   3571篇
  2014年   4694篇
  2013年   7342篇
  2012年   9290篇
  2011年   9694篇
  2010年   6245篇
  2009年   5635篇
  2008年   8803篇
  2007年   9678篇
  2006年   9471篇
  2005年   9061篇
  2004年   8729篇
  2003年   8214篇
  2002年   7813篇
  2001年   13368篇
  2000年   13685篇
  1999年   11452篇
  1998年   3039篇
  1997年   2796篇
  1996年   2642篇
  1995年   2550篇
  1994年   2349篇
  1992年   8338篇
  1991年   8471篇
  1990年   8274篇
  1989年   8089篇
  1988年   7322篇
  1987年   7077篇
  1986年   6723篇
  1985年   6524篇
  1984年   4764篇
  1983年   4124篇
  1982年   2470篇
  1979年   4433篇
  1978年   3234篇
  1977年   2737篇
  1976年   2505篇
  1975年   2838篇
  1974年   3359篇
  1973年   3369篇
  1972年   3119篇
  1971年   2951篇
  1970年   2841篇
  1969年   2589篇
  1968年   2539篇
  1967年   2381篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
992.
CCR5Delta32 is a deletion mutation in the chemokine receptor CCR5. Liver inflammatory activity was found to be significantly reduced (P = 0.005) in Jewish Israeli patients infected with the hepatitis C virus (HCV) carrying the CCR5Delta32 allele. The CCR5Delta32 allele does not alter susceptibility to HCV infection; however, it may play a role in the progression and outcome of the disease.  相似文献   
993.
Furosemide is a potent diuretic that affects water transfer across the respiratory epithelium, which is closely related to the transepithelial potential difference (PD). Water is a critical factor that determines mucus transport; an important lung defence mechanism that removes particles and microorganisms from the respiratory system. The aim of the present study was to investigate the acute effects of furosemide and hypovolaemia on tracheal PD and mucus properties. A total of 36 male mixed-breed dogs were submitted to anaesthesia, mechanical ventilation and haemodynamic monitoring. They were randomly assigned to three groups consisting of: a control group, a furosemide (40 mg i.v.) + hypovolaemia group, and a furosemide (40 mg i.v.) + volume replacement group. Tracheal PD and mucus samples were collected at time 0, 1 and 2 h after intervention. Mucus properties were analysed by means of a magnetic microrheometer and in vitro mucociliary transportability on the frog palate. Compared to controls, furosemide decreased PD to intermediate values, and only significantly when associated with hypovolaemia (-13+/-5 and -8+/-2 mV, time 0 and 2 h, respectively). In addition to the direct effect of furosemide, these results indicate that hypovolaemia also affects ion transport in the tracheal membrane. Furosemide and hypovolemia have no acute effects on respiratory mucus properties.  相似文献   
994.
995.
996.
The sex hormone-binding globulin (SHBG) androgen sensitivity test has been used as a simple method to assess androgen receptor function in vivo. After a short term oral administration of the anabolic-androgenic steroid stanozolol the mean nadir serum concentration of SHBG is used as a measure of androgen response. We performed this test in order to evaluate its applicability in 16 patients with intersexual genital status: eleven with 46,XY gonadal dysgenesis and three with true hermaphroditism (group I), and in two patients with androgen insensitivity syndrome (AIS, group II). Ten healthy adult volunteers served as controls. In the two patients with AIS (group II) we found a diminished decrease of serum SHBG to 80.1 % and 80.7 %, respectively, indicating slight residual androgen responsiveness. In eleven patients of group I who were not on hormone replacement therapy, a mean nadir level of 51.7 +/- 8.7 % was found. In the controls the mean nadir serum SHBG level was significantly higher (62.7 +/- 5.2 %), probably due to interference of endogenous androgens and contraceptive medication with the stanozolol-induced SHBG decrease. In three gonadectomised patients who were on hormone replacement therapy the initial SHBG concentration was increased (513.5 +/- 239.1 nmol/l); the mean nadir SHBG concentration of 45.6 +/- 9.8 % of the initial level indicates an increased sensitivity of the test in patients in whom the counteracting ovarian androgens are absent. Our findings confirm that under standard test conditions the SHBG androgen sensitivity test is a simple diagnostic tool for the detection of androgen receptor malfunction.  相似文献   
997.
Purpose: To report clinically, anotomically and angiographically documented cystoid macular edema (CME) associated with the use of latanoprost in 2 uncomplicated pseudophakic eyes. Methods: Retrospective rewiev of 2 patients who had history of latanoprost use and uncomplicated cataract surgery, described  相似文献   
998.
Cholinergic antagonists have been used since the early 1900s as bronchodilators for chronic obstructive pulmonary disease (COPD). The present study investigated whether an oral muscarinic M3-selective anticholinergic agent (OrM3) would provide an improved therapeutic advantage compared with an inhaled anticholinergic agent in patients with COPD. A 6-week, multicentre, randomised, placebo- and active-controlled, parallel-group study was performed at 56 sites in the USA. In total, 412 male and female patients (aged 35-86 yrs) with a clinical history consistent with COPD were randomised to receive OrM3 0.5, 2, 3 or 4 mg orally once daily, ipratropium bromide 36 mug by inhalation four times daily or placebo. OrM3 demonstrated a significant dose-related improvement in serial forced expiratory volume in one second and a trend for dose-related improvement in patient-reported symptoms compared with placebo. However, at a dose that provided efficacy less than that of ipratropium, the incidence of dose-related, mechanism-based side-effects for OrM3 exceeded those observed for ipratropium. In patients with chronic obstructive pulmonary disease, the oral M3-selective agent did not offer a therapeutic advantage over inhaled ipratropium. These results do not support the hypothesis that high selectivity for muscarinic M3 receptors over airway neuronal M2 receptors will represent a more effective therapy than current inhaled anticholinergics in obstructive airway disease.  相似文献   
999.
1000.
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