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   6147篇
  免费   532篇
  国内免费   41篇
耳鼻咽喉   47篇
儿科学   104篇
妇产科学   297篇
基础医学   733篇
口腔科学   136篇
临床医学   684篇
内科学   1356篇
皮肤病学   73篇
神经病学   610篇
特种医学   328篇
外科学   686篇
综合类   131篇
一般理论   2篇
预防医学   363篇
眼科学   167篇
药学   353篇
中国医学   64篇
肿瘤学   586篇
  2023年   36篇
  2022年   69篇
  2021年   140篇
  2020年   82篇
  2019年   180篇
  2018年   203篇
  2017年   165篇
  2016年   185篇
  2015年   235篇
  2014年   268篇
  2013年   336篇
  2012年   440篇
  2011年   468篇
  2010年   295篇
  2009年   282篇
  2008年   329篇
  2007年   302篇
  2006年   356篇
  2005年   262篇
  2004年   263篇
  2003年   236篇
  2002年   207篇
  2001年   155篇
  2000年   143篇
  1999年   118篇
  1998年   52篇
  1997年   49篇
  1996年   38篇
  1995年   21篇
  1994年   26篇
  1993年   27篇
  1992年   73篇
  1991年   74篇
  1990年   58篇
  1989年   63篇
  1988年   38篇
  1987年   38篇
  1986年   48篇
  1985年   35篇
  1984年   30篇
  1983年   33篇
  1982年   24篇
  1981年   22篇
  1979年   20篇
  1978年   19篇
  1977年   16篇
  1975年   14篇
  1974年   30篇
  1973年   21篇
  1972年   18篇
排序方式: 共有6720条查询结果,搜索用时 15 毫秒
71.
Clinical Rheumatology - The data concerning the association between dengue viruses (DV) infection and autoimmune diseases (ADs) remain unclear and are scarce. This nationwide population-based...  相似文献   
72.
Several studies have shown cardiovascular benefit in treating hypercholesterolemia with HMG-CoA reductase inhibitor. However, in addition to the lowering of cholesterol, the beneficial effects of this inhibitor reflect other pharmacological activities. Whether these beneficial effects are partly mediated by changes in fibrinolytic factors remains to be proven, since clinical studies on the effects of HMG-CoA reductase inhibitors on fibrinolytic factors have not yielded consistent results. The purpose of this study was to evaluate the effects of fluvastatin on fibrinolytic factors in hypercholesterolemic patients. After 6 weeks on a low-fat, low-cholesterol diet, 23 outpatients known to have primary hypercholesterolemia with low density lipoprotein cholesterol (LDL-C) > or = 130 mg/dl with at least 2 risk factors or fasting LDL-C > or = 160 mg/dl were selected for the study. Venous blood samples were collected at baseline and at 8 weeks after fluvastatin therapy (40 mg/day) to measure of tissue plasminogen activator (t-PA), plasminogen activators inhibitor-1 (PAI-1), fibrinogen, D-dimer and lipid profile. After 8 weeks of therapy, fluvastatin reduced serum cholesterol by 11% (261.9 mg/dl vs 233.2 mg/dl, P < 0.01) and LDL-C by 22% (191.9 mg/dl vs 149.3 mg/dl, P < 0.01). D-dimer was significantly decreased (0.38 ng/L vs 0.28 ng/L, P = 0.02) and tPA, PAI-1 and fibrinogen tended to decrease after therapy. Fluvastatin therapy improved fibrinolytic profile; the result of this study may in part explain the benefit of HMG-CoA reductase inhibitor on cardiovascular system other than lipid lowering.  相似文献   
73.
74.
Two cases of double outlet right ventricle with subpulmonary ventricular septal defect treated by arterial switch operations are reported. The anatomical problems of coronary artery transfer, occult outflow tract obstruction and position of the pulmonary bifurcation are discussed. Cases of double outlet right ventricle and subpulmonary ventricular septal defect with anterior-to-posterior relation of the great arteries are suited to the repair techniques pioneered by Jatene for complete transposition and ventricular septal defect. Cases in which the great arteries are side-by-side pose more difficult problems, partly because of the more complex and varied anatomy of the coronary arteries, and because of the spatial relation of the roots of the great arteries. Although it may be possible to overcome these technical problems, we have reservations about the reproducibility of such a procedure. We believe, however, that cases of this type are best treated without recourse to "inflow" correction. The options are either the arterial switch procedure or a modified Rastelli operation.  相似文献   
75.
Compared with the coronary arterial system, less attention has been paid to the coronary venous system. In the current era, there are therapeutic options for arrhythmias and for heart failure that use the coronary venous system to access target areas. We review the arrangement of the main cardiac veins to provide a morphologic background to interventionists. In general, the venous system is a useful conduit for delivery of percutaneous transcatheter treatment. But, variability in terms of valves, diameter, angulation, extent of muscular sleeves, proximity to other cardiac structures, and cross-over spatial relationship with branches of coronary arteries have implications for practitioners seeking to make use of the system.  相似文献   
76.
77.
To further clarify the association of HLA DR alleles with type 1 diabetes mellitus and the influence of age-onset and gender on type 1 diabetes, we investigated HLA-DR in 76 child onset Chinese (36 males) type 1 diabetes patients and 154 normal controls by using PCR-SSP (sequence specific primer). The mean age of onset of diabetes patients was 8.43 +/- 3.96 year-old. Our results revealed that the frequencies of DR3, DR4 and DR9 in diabetes patients were significantly higher than those in control group (all P < 0.01). The susceptible alleles were DR3, DR4, DR9, with relative risks of 8.25, 2.57 and 2.67, respectively. The protective alleles to type 1 diabetes were DR 2, DR8, DR11 and DR12 with relative risk of 0.24, 0.15, 0.16 and 0.39, respectively. There were no significant differences between the frequencies of HLA DR 3, DR4, DR9, DR3/4, DR3/9 and DR4/9 in male and female diabetic children. We divided the diabetes patients into three groups according to their age of onset (1-5 years old, 6-10 years old and 11-17 years old). There was a trend that the frequencies of DR9 decreased with the increase of age at onset, but there was no significant difference of DR3, DR4, DR9, DR3/4, DR3/9 and DR4/9 frequencies between diabetes children with age onset 0-10 years and 11-17 years. As to the influence of gender on the HLA genotypes, the frequency of DR3/4 decreased with the increase of age at onset for male patients and the frequency of DR3/4 increased with the increase of age at onset for female patients.  相似文献   
78.
79.
80.
Cardiac fibroblasts in culture produce factor(s) that induce hypertrophy of neonatal rat ventricular myocytes in vitro. As in vivo, the myocyte hypertrophy response in culture is characterized by an increase in cell size and contractile protein content, and by the activation of embryonic genes, including the gene for atrial natriuretic peptide. The purpose of this study was to identify the factor(s) produced by fibroblasts that induce myocyte hypertrophy. The fibroblast hypertrophy activity was inhibited using a combination of the endothelin A receptor blocker BQ-123 and an antibody to leukemia inhibitory factor. The individual antagonists each caused a partial inhibition. The mRNAs for both leukemia inhibitory factor and endothelin were detected by RT-PCR analysis and the concentration of both proteins was determined to be approximately 200 pmol/L in the conditioned medium using immunoassays. Purified leukemia inhibitory factor and endothelin each induced distinctive morphological changes in the myocytes. Their combination generated a different morphology similar to that induced by fibroblast conditioned medium. Each factor also induced atrial natriuretic peptide production, but both were required for the myocytes to produce the levels measured after exposure to fibroblast conditioned medium. These results show that hypertrophy activity produced by cardiac fibroblasts in culture is a result of leukemia inhibitory factor and endothelin.  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