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   53278篇
  免费   3453篇
  国内免费   246篇
耳鼻咽喉   670篇
儿科学   1238篇
妇产科学   1279篇
基础医学   7400篇
口腔科学   1542篇
临床医学   5843篇
内科学   11452篇
皮肤病学   830篇
神经病学   5319篇
特种医学   1835篇
外科学   6708篇
综合类   385篇
一般理论   46篇
预防医学   3839篇
眼科学   861篇
药学   3683篇
  1篇
中国医学   64篇
肿瘤学   3982篇
  2023年   307篇
  2022年   545篇
  2021年   1185篇
  2020年   770篇
  2019年   1030篇
  2018年   1254篇
  2017年   1110篇
  2016年   1304篇
  2015年   1373篇
  2014年   1818篇
  2013年   2608篇
  2012年   3928篇
  2011年   4113篇
  2010年   2444篇
  2009年   2233篇
  2008年   3416篇
  2007年   3727篇
  2006年   3358篇
  2005年   3397篇
  2004年   3104篇
  2003年   2893篇
  2002年   2663篇
  2001年   516篇
  2000年   450篇
  1999年   553篇
  1998年   591篇
  1997年   501篇
  1996年   424篇
  1995年   373篇
  1994年   322篇
  1993年   341篇
  1992年   285篇
  1991年   296篇
  1990年   254篇
  1989年   282篇
  1988年   262篇
  1987年   219篇
  1986年   224篇
  1985年   248篇
  1984年   216篇
  1983年   195篇
  1982年   202篇
  1981年   173篇
  1980年   149篇
  1979年   125篇
  1978年   142篇
  1977年   143篇
  1976年   107篇
  1975年   113篇
  1974年   90篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
992.
993.
We analysed endothelial cell membrane microparticles (ECMP) in the peripheral blood of patients with paroxysmal nocturnal haemoglobinuria (PNH) (n = 9), aplastic anaemia (AA) (n = 10), sickle cell disease (SCD) (n = 8), and healthy donors (HD) (n = 11). There was no clinically manifested thrombosis in the PNH or AA group, except one cured thrombophlebitis (PNH), while all SCD patients had a history of vaso-occlusive crises. We used three-colour flow cytometry with blood cell-specific antibodies and antibodies to endothelial antigens CD105 and CD144. Phosphatidylserine-positive microparticles were detected using the annexin V-binding (AVB) assay. The population of CD105+AVB+ ECMP was significantly (P < 0.05) higher in SCD (median: 0.568 x 10(9)/l; 25-75th percentile range: 0.351-0.976 x 10(9)/l) and PNH (0.401 x 10(9)/l; 0.19-0.441 x 10(9)/l) patients when compared with AA (0.122 x 10(9)/l; 0.061-0.172 x 10(9)/l) or HD (0.180 x 10(9)/l; 0.137-0.217 x 10(9)/l) group. Even more pronounced differences were observed in ECMP exhibiting a marker of inflammatory stimulation CD54 (CD105+CD54+). Similarly, ECMP that exhibited endothelial specific and proteolysis-sensitive antigen CD144 were increased in SCD and PNH, but not in AA. Elevated CD54+ ECMP may reflect the inflammatory status of endothelial cells in SCD and PNH, while CD144+ ECMP could indicate continuous endothelial stimulation and/or injury. Analysis of circulating ECMP appears promising to provide useful information on the status of the vascular endothelium in PNH and SCD.  相似文献   
994.
995.

Background

Several studies have found that among patients with ST-elevation myocardial infarction (STEMI) treated by thrombolysis, female sex is associated with a worse outcome. The aim of this study was to investigate sex-related differences in clinical and angiographic findings and in long-term outcome in patients with STEMI treated with primary angioplasty.

Methods

Our population is represented by 1548 consecutive patients with STEMI treated by primary angioplasty from April 1997 to October 2001. All clinical, angiographic, and follow-up data were prospectively collected.

Results

Among 1548 patients, 353 were women (22.8%). Female sex was associated with more advanced age, higher prevalence of diabetes, hypertension, more advanced Killip class, longer ischemia time, and smaller vessel caliber. No difference was observed in terms of procedural success, postprocedural epicardial flow, myocardial perfusion, ST-segment resolution, and enzymatic infarct size. At 1-year follow-up, female sex was associated with a significantly higher 1-year mortality rate at univariate (9.3% vs 4.9 %, RR [95% CI] = 1.79 [1.14 to 2.8], P = .002) but not at multivariate analysis (RR [95% CI] = 1.41 [0.86 to 2.32], P = NS).

Conclusions

This study shows that in patients with STEMI treated by primary angioplasty, women are associated with higher mortality rate in comparison with men, mainly because of their high-risk profile and angiographic features. Female sex did not emerge as an independent predictor of death.  相似文献   
996.
OBJECTIVE: Our objective was to compare the effects of oral vs. transdermal estrogen therapy on C-reactive protein (CRP), IL-6, E- and P-selectin, intercellular adhesion molecule (ICAM)-1 and vascular cell adhesion molecule-1, serum amyloid A, transferrin, prealbumin, IGF-I, SHBG, thyroxine-binding globulin (TBG), and cortisol-binding globulin (CBG) in naturally menopausal women. DESIGN: This was a randomized, open-label crossover clinical trial. A 6-wk withdrawal from prior hormone therapy (baseline) was followed in randomized order by 12-wk oral conjugated equine estrogens (CEEs) (0.625 mg/d) and 12-wk transdermal estradiol (E2) (0.05 mg/d), with oral micronized progesterone (100 mg/d) given continuously during both regimens. RESULTS: A total of 27 women enrolled, and 25 completed both treatment periods. Nine parameters changed significantly during oral CEE (median percent change from baseline; P value): CRP (192%; P <0.001); E-selectin (-16.3%; P = 0.003); P-selectin (-15.3%; P = 0.012); ICAM-1 (-5%; P = 0.015); transferrin (5.3%; P = 0.024); IGF-I (-30.5%; P < 0.001); SHBG (113%; P < 0.001); TBG (38%; P < 0.001); and CBG (20%; P < 0.001). With transdermal E2, only three parameters changed significantly and to a lesser degree: ICAM-1 (-2.1%; P = 0.04); IGF-I (-12.5%; P < 0.001); and SHBG (2.6%; P = 0.042). During oral CEE the intrasubject changes in CRP correlated strongly with the changes in serum amyloid A (r = 0.805; P < 0.001), and were only weakly associated with the changes in SHBG (r = 0.248; nonsignificant), TBG (0.430; P = 0.031), and CBG (r = 0.072; nonsignificant). The log-log relationship between CRP and IL-6 observed at baseline showed a parallel shift during oral CEE, suggesting an amplified hepatic response or a greater sensitivity to IL-6 stimulation. CONCLUSION: Compared with oral CEE, transdermal E2 exerts minimal effects on CRP and the other inflammation and hepatic parameters.  相似文献   
997.
998.

Background

We sought to evaluate the real-world effectiveness and safety of prolonged anticoagulation with rivaroxaban following a provoked venous thromboembolism.

Methods

Using US MarketScan claims from November 2012 to March 2017, we identified adults with ≥1 primary hospitalization or emergency department diagnosis code for venous thromboembolism, a provoking (major or minor, persistent or transient) risk factor, at least 3 months of continuous rivaroxaban treatment, and ≥12 months of continuous insurance benefits prior to their qualifying venous thromboembolism. Patients were categorized as either continuing rivaroxaban or discontinuing anticoagulation (no anticoagulation or nonaspirin antiplatelet agents but may have received aspirin) after the initial 3 months of rivaroxaban treatment (index date). Differences in baseline covariates between cohorts were adjusted for using inverse probability-of-treatment weights based on propensity scores (absolute standardized differences <0.1 achieved for all covariates after adjustment). Twelve month incidences of recurrent venous thromboembolism or major bleeding were compared between cohorts using Cox regression (according to an intention-to-treat methodology) and reported as hazard ratios (HRs) with 95% confidence intervals (CIs).

Results

Among patients experiencing a provoked venous thromboembolism and treated with rivaroxaban for the first 3 months (N=4,990), continued rivaroxaban use beyond 3 months (median [25%, 75% range duration of additional rivaroxaban use?=?3 [2, 5] months) was associated with a 44% (95% CI of 9%-66%) lower hazard of recurrent venous thromboembolism without altering major bleeding risk [HR of 0.87, 95% CI of 0.51-1.49] versus anticoagulation discontinuation (with or without aspirin use).

Conclusions

Our study suggests continuing rivaroxaban after the initial 3 month period was associated with a decreased risk of recurrent venous thromboembolism. The observed reduction in recurrent venous thromboembolism with prolonged rivaroxaban use was not associated with a significant change in major bleeding risk.  相似文献   
999.
1000.
Recent studies on the immunoglobulin variable heavy chain (IgV(H)) genes have revealed that B-cell chronic lymphocytic leukemia (B-CLL) consists of at least 2 clinical entities with either somatically mutated or unmutated V(H) genes. We have analyzed the V(H) gene mutation status and V(H) gene usage in 119 B-CLL cases and correlated them to overall survival. A novel finding was the preferential use of the V(H)3-21 gene in mutated cases, whereas biased V(H)1-69 gene usage was found in unmutated cases as previously reported. Interestingly, the subset of mutated cases using the V(H)3-21 gene displayed distinctive genotypic/phenotypic characteristics with shorter average length of the complementarity determining region 3 and clonal expression of lambda light chains. In addition, this mutated subset showed significantly shorter survival than other mutated cases and a similar clinical course to unmutated cases. We therefore suggest that B-CLL cases with mutated V(H)3-21 genes may constitute an additional entity of B-CLL.  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