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   6385篇
  免费   524篇
  国内免费   19篇
耳鼻咽喉   23篇
儿科学   132篇
妇产科学   126篇
基础医学   1041篇
口腔科学   38篇
临床医学   690篇
内科学   1329篇
皮肤病学   125篇
神经病学   717篇
特种医学   138篇
外科学   576篇
综合类   33篇
一般理论   3篇
预防医学   611篇
眼科学   91篇
药学   582篇
中国医学   11篇
肿瘤学   662篇
  2023年   55篇
  2022年   86篇
  2021年   206篇
  2020年   104篇
  2019年   191篇
  2018年   200篇
  2017年   128篇
  2016年   169篇
  2015年   183篇
  2014年   251篇
  2013年   345篇
  2012年   534篇
  2011年   499篇
  2010年   285篇
  2009年   213篇
  2008年   424篇
  2007年   454篇
  2006年   399篇
  2005年   363篇
  2004年   369篇
  2003年   335篇
  2002年   286篇
  2001年   53篇
  2000年   36篇
  1999年   64篇
  1998年   64篇
  1997年   45篇
  1996年   44篇
  1995年   32篇
  1994年   21篇
  1993年   22篇
  1992年   24篇
  1991年   15篇
  1990年   26篇
  1989年   25篇
  1988年   21篇
  1987年   19篇
  1986年   12篇
  1985年   27篇
  1984年   12篇
  1983年   15篇
  1982年   17篇
  1981年   18篇
  1980年   10篇
  1979年   16篇
  1978年   15篇
  1973年   9篇
  1970年   8篇
  1969年   11篇
  1965年   8篇
排序方式: 共有6928条查询结果,搜索用时 93 毫秒
951.
Recent data suggest that inhibitory pathways may be involved in the pathophysiology of depression and in the mode of action of some antidepressant interventions. The aim of the present study was to test whether vagus nerve stimulation (VNS) can affect motor cortex excitability. Measures of motor cortical excitability were probed by using single-pulse and paired-pulse transcranial magnetic stimulation at baseline, after 10 weeks of left VNS, and additionally, in an on-off paradigm in 10 patients with treatment-resistant unipolar depression. Ten weeks of VNS was associated with a selective and pronounced increase in intracortical inhibition, whereas no changes occurred in the on-off paradigm. These results suggest that VNS is capable of changing motor cortical excitability in patients with depression.  相似文献   
952.
953.
Increased angiotensinogen (AGT) production by white adipose tissue has been related to not only obesity but also hypertension. Several studies have highlighted the importance of the angiotensin II type 2 receptor (AT2) in the regulation of blood pressure and fat mass, but the relevance of this transporter in a physiopathological model of increased AGT production, as it occurs in obesity, has not yet been investigated. We used transgenic mice that display either a deletion of AT2 (AT2 KO), an overexpression of AGT (OVEX), or both compound mutants (KOVEX). Results demonstrated that adipocyte hypertrophy and increased lipogenic gene expression induced by adipose AGT overproduction was rescued by deletion of AT2. In line with AGT overexpression, KOVEX and OVEX mice have similar increased plasma AGT levels. However, KOVEX mice display a higher blood pressure than OVEX mice. In kidney, renin expression was clearly reduced in OVEX mice, and its expression was normalized in KOVEX mice. Taken together, we demonstrated that the loss of AT2 expression was sufficient to rescue obesity induced by adipose tissue AGT overexpression and confirmed the necessary role of AT2 for the onset of obesity in this model. Furthermore, despite a reduction of adipose mass in KOVEX, AT2 deficiency caused increased renin production, further worsening the hypertension caused by AGT overexpression.  相似文献   
954.
This retrospective study assessed the long-term effect of transfusional exchange therapy on MRA/MRI abnormalities in 24 homozygous sickle-cell anemia (HbSS) children presenting with abnormal brain MRA. The median time elapsed from baseline to last available MRA was 29 months. Follow-up MRAs showed improvement, stabilization or worsening of cerebrovascular lesions in 11, 6 and 7 patients respectively. Complete normalization of MRA was observed in 6 patients within a mean time of 1.4 years, but stenosis recurred at the same location in the 4 patients in whom transfusion therapy was discontinued. Baseline severe stenosis/occlusion of large cerebral arteries and occurrence of moyamoya syndrome were significantly associated with an absence of improvement of the cerebral vasculopathy. These data emphasize the heterogeneity of the course of cerebrovasculopathy in SS children receiving chronic transfusion. Further studies are needed to determine whether different therapeutic approaches have to be considered according to these different evolutive patterns in SS children.  相似文献   
955.
956.
BackgroundAdolescents in Uganda carry a heavy burden of reproductive health problems. Different environment creates different problems.ObjectivesTo study the prevalence of STI and to compare social and behavioral risk factors for Neisseria gonorrhoea (NG) and Chlamydia trachomatis (CT) among sexually experienced young women in one urban and one rural area in Uganda.MethodsConsenting, sexually experienced women, below 20 years, visiting two different youth clinics were asked about social background, genital symptoms and sexual experiences. Vaginal samples were taken for NG and CT and analyzed by PCR.ResultsThe prevalence of NG and/or CT was 20 (6.8%) in the urban and 23 (7.8%) in the rural study site, a non-significant difference. The rural women were often in marital union, 25.3% compared to 12.2% of the urban women (OR 2.4, 95% CI 1.6-3.8) and had experienced more pregnancies and had more children. Their partners were often more than 10 years older. More urban women (42.2%) knew their HIV status compared to rural women (16.2%), OR 2.1 (1.6–2.7), reported more condom use and more sexual partners.ConclusionsMarital status and few sexual partners does not appear to protect young rural women from sexually transmitted infections (STIs), implying that male sexual behavior may have an important impact on women’s risk to be infected.  相似文献   
957.
Ribavirin (CAS 66510-90-5) associated to peginterferon (CAS 99210-65-8) is the current standard treatment for chronic hepatitis C. Exposure to ribavirin influences the virological response and anemia. Therefore monitoring plasma concentration of ribavirin is a useful tool for individualizing ribavirin dosing regimens. Ribavirin is a substrate of several nucleoside transporters that play a role in its distribution in erythrocytes. After blood sampling, it is essential to limit this mechanism. The aim of this study was to evaluate the influence of temperature and time on ribavirin plasma concentrations. Two blood samples, collected in EDTA tubes, were taken at the same time from 23 patients. One sample was conserved on ice whereas the second one was kept at room temperature during transport to the laboratory. Upon receipt at the laboratory and at different times post-reception (from 1 to 3 h), 1.5 mL of blood from each sample was centrifuged to obtain plasma that was then stored at -20 degrees C until assay. Samples were maintained in the same conditions as during transport for the 3 h. Plasma ribavirin was analysed using an HPLC-UV system. The results showed that mean loss of ribavirin concentration, for samples kept on ice as well as at room temperature, was less than 3%, 9% and 13% after 1, 2 and 3 h, respectively. These results suggest that blood samples for ribavirin analysis can be sent at room temperature within a period of 2 h between sampling and centrifugation.  相似文献   
958.
Phospholipases A2 (PLA2s) form a family of enzymes catalyzing the hydrolysis of membrane phospholipids into arachidonic acid, which is the major precursor of pro-inflammatory eicosanoids. As a result, PLA2s have been considered as potential targets in anti-inflammatory drug discovery.Marine natural products are a rich source of bioactive compounds, including PLA2 inhibitors. Here, we review the properties of marine PLA2 inhibitors identified since the first discovery of PLA2 inhibitory activity in the marine natural product manoalide in the mid 1980s.  相似文献   
959.

Purpose

Fenugreek seeds (Trigonella foenum-graecum L.) have long been used as a herbal medicine for treating metabolic and nutritive dysfunctions. They have been shown to modulate feeding behaviour in animals. We have recently observed a selective decrease in fat consumption in healthy normal weight volunteers treated with a hydro-alcoholic seed extract. However, strong clinical data on the effects of fenugreek seeds on energy intake are lacking, especially in overweight individuals. The aim of our study was to investigate the effects of a repeated administration of a fenugreek seed extract on the eating behaviour of overweight subjects.

Methods

Thirty-nine healthy overweight male volunteers completed a 6-week double-blind randomized placebo-controlled parallel trial of a fixed dose of a fenugreek seed extract. Main endpoints were energy intake (dietary records and meal test), weight, fasting and post-absorptive glucose and insulin, appetite/satiety scores and oxidative parameters.

Results

Daily fat consumption, expressed as the ratio fat reported energy intake/total energy expenditure (fat-REI/TEE), was significantly decreased in our overweight subjects administered the fenugreek seed extract relative to those receiving the placebo (fat-REI/TEE 0.26?±?0.02 vs. 0.30?±?0.01, respectively; P?=?0.032). We also observed a significant decrease in the insulin/glucose ratio in subjects treated with fenugreek seed extract relative to the placebo group (0.89?±?0.09 vs. 1.06?±?0.10 mUI mmol?1, respectively; P?=?0.044). No significant effect was observed on weight, appetite/satiety scores or oxidative parameters.

Conclusion

The repeated administration of a fenugreek seed extract slightly but significantly decreased dietary fat consumption in healthy overweight subjects in this short-term study.  相似文献   
960.
Relatively few international comparisons of the incidence of influenza related to climate parameters have been performed, particularly in the Eastern hemisphere. In this study, the incidence of influenza and climate data such as temperature, relative humidity, and rainfall, from cities at different latitudes with contrasting climates: Singapore, Hong Kong (China), Ulaanbaatar (Mongolia), Vancouver (Canada), and three Australian cities (Brisbane, Melbourne and Sydney) were examined to determine whether there was any overall relationship between the incidence of influenza and climate. Applying time‐series analyses to the more comprehensive datasets, it was found that relative humidity was associated with the incidence of influenza A in Singapore, Hong Kong, Brisbane, and Vancouver. In the case of influenza B, the mean temperature was the key climate variable associated with the incidence of influenza in Hong Kong, Brisbane, Melbourne, and Vancouver. Rainfall was not significantly correlated with the incidence of influenza A or B in any of these cities. J. Med. Virol. 82:1958–1965, 2010. © 2010 Wiley‐Liss, Inc.  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