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   14068篇
  免费   839篇
  国内免费   46篇
耳鼻咽喉   197篇
儿科学   428篇
妇产科学   234篇
基础医学   1934篇
口腔科学   235篇
临床医学   1254篇
内科学   2596篇
皮肤病学   301篇
神经病学   1815篇
特种医学   907篇
外国民族医学   9篇
外科学   2536篇
综合类   58篇
一般理论   4篇
预防医学   610篇
眼科学   245篇
药学   793篇
中国医学   13篇
肿瘤学   784篇
  2023年   130篇
  2022年   107篇
  2021年   318篇
  2020年   266篇
  2019年   330篇
  2018年   390篇
  2017年   348篇
  2016年   438篇
  2015年   406篇
  2014年   537篇
  2013年   666篇
  2012年   1030篇
  2011年   1009篇
  2010年   590篇
  2009年   482篇
  2008年   778篇
  2007年   779篇
  2006年   698篇
  2005年   564篇
  2004年   561篇
  2003年   526篇
  2002年   466篇
  2001年   319篇
  2000年   312篇
  1999年   271篇
  1998年   89篇
  1997年   58篇
  1996年   71篇
  1995年   61篇
  1994年   56篇
  1993年   62篇
  1992年   163篇
  1991年   159篇
  1990年   162篇
  1989年   141篇
  1988年   128篇
  1987年   100篇
  1986年   91篇
  1985年   116篇
  1984年   85篇
  1983年   70篇
  1982年   46篇
  1979年   65篇
  1978年   44篇
  1977年   52篇
  1975年   43篇
  1974年   47篇
  1973年   55篇
  1972年   49篇
  1971年   49篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
1.
Purpose

A longer menarche-to-first pregnancy window of susceptibility (WOS) is associated with increased breast cancer risk. Whether physical activity, an established preventive risk factor, during the menarche-to-first pregnancy WOS offsets breast cancer risk overall or for specific molecular subtypes is unclear.

Methods

We examined the prospective association between physical activity during the menarche-to-first pregnancy WOS and breast cancer risk in the California Teachers Study (N?=?78,940). Recreational physical activity at multiple timepoints were recalled at cohort entry, and converted to metabolic equivalent of task hours per week (MET-hrs/wk). We used multivariable Cox proportional hazards models to estimate hazard ratios (HRs) and 95% confidence intervals (CIs).

Results

We observed 5,157 invasive breast cancer cases over 21.6 years of follow-up. Longer menarche-to-first pregnancy WOS (≥?20 vs.?<?15 years) was associated with higher breast cancer risk (HR?=?1.23, 95% CI?=?1.13–1.34). Women with higher physical activity level during menarche-to-first pregnancy had lower risk of invasive breast cancer (≥?40 vs.?<?9 MET-hrs/wk: HR?=?0.89, 95% CI?=?0.83–0.97) and triple-negative subtype (≥?40 vs.?<?9 MET-hrs/wk: HR?=?0.53, 95% CI?=?0.32–0.87). No association was observed for luminal A-like and luminal B-like subtypes. Higher physical activity level was associated with lower breast cancer risk among women with moderate (15–19 years) menarche-to-first pregnancy intervals (≥?40 vs.?<?9 MET-hrs/wk: HR?=?0.80, 95% CI?=?0.69–0.92), but not with short (<?15 years) or long (≥?20 years) intervals.

Conclusion

Physical activity during a WOS was associated with lower breast cancer risk in our cohort. Understanding timing of physical activity throughout the life course in relationship with breast cancer risk maybe important for cancer prevention strategies.

  相似文献   
2.
Journal of Interventional Cardiac Electrophysiology - The study sought to assess the prognostic impact of chronic kidney disease (CKD) in patients with electrical storm (ES). ES represents a...  相似文献   
3.
Die Anaesthesiologie - Die Implementierung eines Patient Blood Management (PBM) wird zunehmender Standard in der operativen Medizin. Seit einiger Zeit gilt das Interesse auch den vulnerablen...  相似文献   
4.
Die Anaesthesiologie - Auch wenn für Anästhesiologen über Jahrzehnte die Prophylaxe und Therapie postoperativer Schmerzen im Rahmen des postoperativen Patientenkomforts an vorderster...  相似文献   
5.
6.
7.
The foreign body reaction to neuronal electrode implants limits potential applications as well as the therapeutic period. Developments in the basic electrode design might improve the tissue compatibility and thereby reduce the foreign body reaction. In this work, the approach of embedding 3D carbon nanofiber electrodes in extracellular matrix (ECM) synthesized by human fibroblasts for a compatible connection to neuronal cells was investigated. Porous electrode material was manufactured by solution coelectrospinning of polyacrylonitrile and polyamide as a fibrous porogen. Moreover, NaCl represented an additional particulate porogen. To achieve the required conductivity for an electrical interface, meshes were carbonized. Through the application of two different porogens, the electrodes’ flexibility and porosity was improved. Human dermal fibroblasts were cultured on the electrode surface for ECM generation and removed afterwards. Scanning electron microscopy imaging revealed a nano fibrous ECM network covering the carbon fibers. The collagen amount of the ECM coating was quantified by hydroxyproline-assays. The modification with the natural protein coating on the electrode functionality resulted in a minor increase of the electrical capacity, which slightly improved the already outstanding electrical interface properties. Increased cell numbers of SH-SY5Y cell line on ECM-modified electrodes demonstrated an improved cell adhesion. During cell differentiation, the natural ECM enhanced the formation of neurites regarding length and branching. The conducted experiments indicated the prevention of direct cell-electrode contacts by the modification, which might help to shield temporary the electrode from immunological cells to reduce the foreign body reaction and improve the electrodes’ tissue integration.  相似文献   
8.
Introduction and objectivesLong-term outcomes of unselected patients treated with bioresorbable vascular scaffold (BVS) implantation are lacking, especially for the period after complete dissolution of the BVS. This study sought to evaluate 5-year outcomes in patients treated with BVS in routine practice.MethodsConsecutive patients who underwent implantation of everolimus-eluting BVS during routine clinical practice at 2 high-volume centres in Germany were studied. The patients were followed-up for up to 5 years. The primary endpoints of interest were the composite of death, myocardial infarction and target lesion revascularization, as well as definite scaffold thrombosis.ResultsA total of 419 patients (mean age 66.6 ± 10.9 years; 31.5% had diabetes) were included, of whom 38.9% presented with an acute coronary syndrome. Of the 527 lesions treated, 49.0% were classified as complex and 13.1% were bifurcation lesions. At 5 years, the composite clinical endpoint occurred in 33.1% of patients and definite scaffold thrombosis occurred in 4.7%. Most definite scaffold thrombosis occurred within 2 years after BVS implantation.ConclusionsIn patients treated with BVS implantation in routine clinical practice the rates of adverse clinical events at 5 years were high, including a considerable incidence of scaffold thrombosis.  相似文献   
9.
10.
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