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   8712篇
  免费   522篇
  国内免费   58篇
耳鼻咽喉   64篇
儿科学   188篇
妇产科学   145篇
基础医学   1142篇
口腔科学   179篇
临床医学   893篇
内科学   2079篇
皮肤病学   218篇
神经病学   761篇
特种医学   372篇
外科学   1305篇
综合类   15篇
一般理论   3篇
预防医学   701篇
眼科学   69篇
药学   574篇
中国医学   41篇
肿瘤学   543篇
  2024年   6篇
  2023年   40篇
  2022年   74篇
  2021年   176篇
  2020年   134篇
  2019年   233篇
  2018年   274篇
  2017年   159篇
  2016年   202篇
  2015年   227篇
  2014年   352篇
  2013年   489篇
  2012年   672篇
  2011年   726篇
  2010年   401篇
  2009年   360篇
  2008年   578篇
  2007年   675篇
  2006年   594篇
  2005年   583篇
  2004年   579篇
  2003年   502篇
  2002年   460篇
  2001年   65篇
  2000年   59篇
  1999年   74篇
  1998年   89篇
  1997年   70篇
  1996年   60篇
  1995年   50篇
  1994年   42篇
  1993年   41篇
  1992年   16篇
  1991年   39篇
  1990年   16篇
  1989年   20篇
  1988年   19篇
  1987年   13篇
  1986年   21篇
  1985年   21篇
  1984年   11篇
  1983年   10篇
  1982年   10篇
  1981年   11篇
  1980年   6篇
  1979年   6篇
  1977年   4篇
  1976年   3篇
  1972年   3篇
  1968年   3篇
排序方式: 共有9292条查询结果,搜索用时 0 毫秒
91.
Patients with acute myocardial infarction (AMI) who do not receive early reperfusion therapy are at high risk of reinfarction or death, and the efficacy and safety of antithrombotic therapy in this group of patients has not been evaluated. Enoxaparin is a low-molecular-weight heparin (LMWH) that has previously been shown to reduce the incidence of ischemic events in patients with unstable angina or non–Q-wave MI. The principal aims of the TETAMI study are to investigate the efficacy and safety of treatment with enoxaparin or tirofiban (a glycoprotein IIb/IIIa receptor antagonist) alone or in combination for 2 to 8 days in patients with AMI who are not eligible for early reperfusion therapy. In this 2 by 2 factorial design study approximately 900 patients will be randomly assigned, in a blinded manner, to one of four treatments: enoxaparin alone, enoxaparin plus tirofiban, unfractionated heparin (UFH), or UFH plus tirofiban, with appropriate matched placebos. The primary end point is the composite of death, recurrent AMI, and recurrent angina, analyzed at 30 days after AMI. The design and methods of the TETAMI study are described in this article.  相似文献   
92.
Plasmodium falciparum sensitivity to quinine in São Tomé was determined by in vivo and in vitro tests in 56 children with mild or cerebral malaria. Chloroquine sensitivity was assessed by in vitro tests in 105 parasitaemic asymptomatic children from the same community as the cases. The WHO standard methodology was used. No resistance to quinine was found by in vivo or in vitro tests in either group of patients or in asymptomatic children, although some degree of chloroquine resistance was found with the in vitro test. This was more common in patients than in asymptomatic children. Chloroquine resistance may be explained by the recent history of malaria in São Tomé Island, which caused an important decrease of immunity among the population and consequently the emergence of resistant strains. Implications of the use of in vivo / in vitro tests for determining the antimalarial drug policy within the primary health care system are discussed.  相似文献   
93.

Background

Supraventricular tachycardias (SVT) are a common arrhythmia therefore an accurate diagnosis is of clinical importance. Although an ECG performed during tachycardia greatly aids diagnosis, patient history and predisposing factors also improve diagnostic accuracy.

Methods

This prospective study included 100 consecutive patients undergoing electrophysiological study for SVT with the aim to reassess their clinical characteristics and describe frequent predisposing factors, such as the “sign of lace‐tying” that to our knowledge has not previously been reported. Each patient completed an extensive questionnaire (70 questions) during their hospital stay.

Results

Our series comprised: 67% of patients with atrioventricular nodal reentrant tachycardia (AVNRT); 24% with an accessory pathway; and 9% presented atrial tachycardia. Half of the population were male and 29% of the cohort presented hypertension. Syncope during tachycardia appeared in 15% of patients, dizziness in 52% and thoracic pain in 59%. We encountered a predisposing risk factor for SVT in 53% of cases; with 32% exhibiting an anteflexion of the trunk termed the “sign of lace‐tying.” Data also showed that younger patients tended to present AVRT and regular pounding in the neck appeared only in patients with AVNRT.

Conclusions

Overall, our study has highlighted the importance of considering clinical signs and patient characteristics both before and during SVT for the precise diagnosis of paroxysmal SVT. Furthermore, 32% of patients presented the “sign of lace‐tying” or body position change before SVT, implying a diagnosis of SVT.
  相似文献   
94.
95.

Objective

To identify potential prognostic factors that may predict clinical improvement of patients treated with different physical therapy interventions in the short-term.

Methods

This is a prospective cohort study. A total of 616 patients with chronic non-specific low back pain treated with interventions commonly used by physical therapists were included. These patients were selected from five randomized controlled trials. Multivariate linear regression models were used to verify if sociodemographic characteristics (age, gender, and marital status), anthropometric variables (height, body mass, and body mass index), or duration of low back pain, pain intensity at baseline, and disability at baseline could be associated with clinical outcomes of pain intensity and disability four weeks after baseline.

Results

The predictive variables for pain intensity were age (β = 0.01 points, 95% CI = 0.00 to 0.03, p = 0.03) and pain intensity at baseline (β = 0.23 points, 95% CI = 0.13 to 0.33, p = 0.00), with an explained variability of 4.6%. Similarly, the predictive variables for disability after four weeks were age (β = 0.03 points, 95% CI = 0.00 to 0.06, p = 0.01) and disability at baseline (β = 0.71 points, 95% CI = 0.65 to 0.78, p = 0.00), with an explained variability of 42.1%.

Conclusion

Only age, pain at baseline and disability at baseline influenced the pain intensity and disability after four weeks of treatment. The beta coefficient for age was statistically significant, but the magnitude of this association was very small and not clinically important.  相似文献   
96.
97.
98.
The role of beta-chemokines in controlling HIV replication in vivo is still controversial. Therefore, the association between HIV-1 plasma viral load and the capacity of CD4(+) and CD8(+) T cells to produce beta-chemokines was studied in 28 antiretroviral drug-na?ve HIV-1-infected female sex workers in Abidjan, C?te d'Ivoire. Percentages of beta-chemokine-positive T cells were measured in peripheral blood mononuclear cells by flow cytometry after intracellular staining for RANTES (regulated on activation, normal T expressed and secreted), macrophage inflammatory protein (MIP)-1alpha, and MIP-1beta. HIV-1-infected subjects had higher percentages of MIP-1alpha- and MIP-1beta-positive CD4(+) and CD8(+) T cells (p < 0.02) and of RANTES-positive CD8(+) T cells (p = 0.054) than uninfected controls. Percentages of RANTES- and MIP-1beta-positive CD8(+) T cells correlated directly with HIV-1 plasma viral load (p < 0.02). Percentages of beta-chemokine-positive CD4(+) and CD8(+) T cells correlated directly with percentages of HLA-DR-positive T cells (p < 0.02) and inversely (except RANTES in CD4(+) T cells) with absolute numbers of CD4(+) T cells (p < 0.05) in peripheral blood. These data indicate that increased percentages of beta-chemokine-producing T cells in HIV-1-infected subjects correlate with disease progression and are a sign of viremia-driven chronic T cell activation.  相似文献   
99.
Pathogenesis of systemic scleroderma: immunological aspects   总被引:3,自引:0,他引:3  
Systemic sclerosis (SSc) is a connective tissue disorder that is characterized by excessive collagen synthesis by fibroblasts and by vascular hyperreactivity and obliteration phenomena. Excessive collagen production is the consequence of abnormal interactions between endothelial cells, fibroblasts and mononuclear cells. Immunological abnormalities are present very early in the development of SSc. Mononuclear cells, particularily macrophages and T lymphocytes play a prominent role in fibroblast activation and collagen synthesis through the cytokines they produce. Thus, lymphocytic infiltrates in the skin and in the lung are preferentially composed of CD8+ T lymphocytes, that produce important amounts of interleukin 4 (IL-4). The effects of IL-4 are added to these of transforming growth factor B (TGF-B) and connective tissue growth factor (CTGF) that stimulate collagen synthesis by fibroblasts. T lymphocytes produce important amounts of gamma interferon (INF-gamma) that is the best inhibitor of collagen synthesis by fibroblasts. However, the inhibitory effect of INF-gamma on collagen synthesis is diminished in SSc patients. Numerous autoantibodies can be evidenced in the serum of SSc patients. Three of them are specific for SSc and mutually exclusive: anti-centromere antibodies (Ab) in limited SSc, anti-Scl70 Ab in diffuse SSc and anti-RNA polymerase III Ab in diffuse SSc with renal involvement. These autoantibodies are good prognosis markers but their pathogenic role remains uncertain.  相似文献   
100.
Among protease inhibitors, atazanavir has not been associated with urolithiasis in clinical studies. We describe 11 cases of atazanavir-associated urolithiasis in patients with human immunodeficiency virus (HIV) infection. Patients with low water intake, high urinary pH, and a prior history of urinary stones may have a higher risk of atazanavir-associated urine crystallization.  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