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   7060篇
  免费   556篇
  国内免费   116篇
耳鼻咽喉   48篇
儿科学   150篇
妇产科学   309篇
基础医学   795篇
口腔科学   151篇
临床医学   811篇
内科学   1577篇
皮肤病学   107篇
神经病学   635篇
特种医学   585篇
外科学   730篇
综合类   159篇
一般理论   2篇
预防医学   403篇
眼科学   189篇
药学   396篇
中国医学   65篇
肿瘤学   620篇
  2023年   41篇
  2022年   70篇
  2021年   142篇
  2020年   86篇
  2019年   187篇
  2018年   210篇
  2017年   169篇
  2016年   194篇
  2015年   245篇
  2014年   283篇
  2013年   346篇
  2012年   448篇
  2011年   480篇
  2010年   325篇
  2009年   327篇
  2008年   343篇
  2007年   346篇
  2006年   371篇
  2005年   282篇
  2004年   272篇
  2003年   248篇
  2002年   216篇
  2001年   174篇
  2000年   163篇
  1999年   127篇
  1998年   134篇
  1997年   119篇
  1996年   97篇
  1995年   72篇
  1994年   69篇
  1993年   71篇
  1992年   94篇
  1991年   89篇
  1990年   80篇
  1989年   97篇
  1988年   72篇
  1987年   64篇
  1986年   70篇
  1985年   57篇
  1984年   48篇
  1983年   44篇
  1982年   41篇
  1981年   31篇
  1980年   23篇
  1979年   25篇
  1978年   25篇
  1977年   32篇
  1976年   22篇
  1975年   27篇
  1974年   30篇
排序方式: 共有7732条查询结果,搜索用时 4 毫秒
91.
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   
92.
93.
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   
94.
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   
95.
96.
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   
97.
98.
99.
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   
100.
Background. Endothelial-derived microparticles (EDMPs) and platelet-derived microparticles (PDMPs) have been reported to be increasing in various diseases including malignant diseases. Here, we investigated whether these MPs may be useful biomarkers for predicting lung cancer (LC) disease status, cell type, or metastasis. Methods and Results. One hundred and thirty LC patients were prospectively enrolled into the study between April 2011 and February 2012. Flow cytometric analysis demonstrated that the circulating levels of platelet-derived activated MPs (PDAc-MPs), platelet-derived apoptotic MPs (PDAp-MPs), endothelial-derived activated MPs (EDAc-MPs), and endothelial-derived apoptotic MPs (EDAp-MPs) were significantly higher in LC patients than in 30 age- and gender-matched normal control subjects (all P < 0.05). Additionally, circulating level of PDAc-MPs was significantly lower (P = 0.031), whereas the circulating levels of the other three biomarkers did not differ (all P > 0.1) in early stage versus late stage LC patients. Furthermore, the circulating levels of the four types of MPs did not differ among patients with different disease statuses (i.e., disease controlled, disease progression, and disease without treatment, i.e., fresh case) (all P > 0.2) or between patients with or without LC metastasis (all P > 0.5). Moreover, only the circulating level of EDAp-MPs was significantly associated with the different cell types (i.e., squamous cell carcinoma, adenocarcinoma, and small cell carcinoma) of LC (P = 0.045). Conclusion. Circulating MP levels are significantly increased in LC patients as compared with normal subjects. Among the MPs, only an increased level of EDAp-MPs was significantly associated with different LC cell types.  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