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   2220456篇
  免费   170459篇
  国内免费   7359篇
耳鼻咽喉   29710篇
儿科学   71348篇
妇产科学   60028篇
基础医学   308711篇
口腔科学   62110篇
临床医学   199763篇
内科学   441406篇
皮肤病学   52163篇
神经病学   177336篇
特种医学   90437篇
外国民族医学   472篇
外科学   343665篇
综合类   49429篇
现状与发展   3篇
一般理论   660篇
预防医学   169044篇
眼科学   48841篇
药学   165218篇
  10篇
中国医学   4559篇
肿瘤学   123361篇
  2018年   22481篇
  2017年   17792篇
  2016年   20953篇
  2015年   23344篇
  2014年   32255篇
  2013年   47935篇
  2012年   61241篇
  2011年   65405篇
  2010年   39972篇
  2009年   38513篇
  2008年   61081篇
  2007年   65206篇
  2006年   66677篇
  2005年   63964篇
  2004年   61232篇
  2003年   59430篇
  2002年   56952篇
  2001年   112402篇
  2000年   115758篇
  1999年   96654篇
  1998年   26873篇
  1997年   23919篇
  1996年   24678篇
  1995年   24281篇
  1994年   22444篇
  1993年   21145篇
  1992年   77205篇
  1991年   74881篇
  1990年   72676篇
  1989年   69767篇
  1988年   63951篇
  1987年   62672篇
  1986年   59076篇
  1985年   56461篇
  1984年   42089篇
  1983年   35421篇
  1982年   21088篇
  1981年   18670篇
  1980年   17670篇
  1979年   37861篇
  1978年   26627篇
  1977年   23028篇
  1976年   20672篇
  1975年   22328篇
  1974年   26129篇
  1973年   25109篇
  1972年   23510篇
  1971年   21849篇
  1970年   20016篇
  1969年   19013篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
21.
22.
Comprehensive evidence regarding the treatment of non-anaemic iron deficiency in patients undergoing valvular heart surgery is lacking. This study aimed to investigate the association between non-anaemic iron deficiency and postoperative outcomes in these patients. We retrospectively analysed 321 patients of which 180 (56%) had iron deficiency (defined as serum ferritin < 100 ng.ml-1 or < 300 ng.ml-1 with transferrin saturation < 20%). While the iron-deficient group had lower pre-operative haemoglobin levels than the non-iron deficient group (median (IQR [range]) 134 (127–141 [120–172]) g.l-1, 143 (133–150 [120–179]) g.l-1, p = 0.001), there was no between-group difference in allogeneic red blood cell transfusion. Median (IQR [range]) days alive and out of hospital at postoperative day 90 was 1 day shorter in the iron-deficient group (80 (77–82 [9–85]) days vs. 81 (79–83 [0–85]) days, p = 0.026). In multivariable analysis, only cardiopulmonary bypass duration (p = 0.032) and intra-operative allogeneic red blood cell transfusion (p = 0.011) were significantly associated with reduced days alive and out of hospital at postoperative day 90. Iron deficiency did not exert any adverse influence on secondary outcomes except length of hospital stay. Our findings indicate that non-anaemic iron deficiency alone is not associated with adverse effects in patients undergoing valvular heart surgery when it does not translate into an increased risk of allogeneic transfusion.  相似文献   
23.
24.
In this paper we present a coupled Finite Element Method – Boundary Element Method (FEM-BEM) approach for the solution of the free-boundary axi-symmetric plasma equilibrium problem. The proposed method, obtained from an improvement of the Hagenow-Lackner coupling method, allows to efficiently model the equilibrium problem in unbounded domains by discretizing only the plasma region; the external conductors can be modelled either as 2D or 3D models, according to the problem of interest. The paper explores different iterative methods for the solution of the nonlinear Grad-Shafranov equation, such as Picard, Newton-Raphson and Newton-Krylov, in order to provide a robust and reliable tool, able to handle large-scale problems (e.g. high resolution equilibria). This method has been implemented in the FRIDA code (FRee-boundary Integro-Differential Axisimmetric – https://github. om/matteobonotto/ FRIDA), together with a suitable Adaptive Integration Technique (AIT) for the computation of the source term. FRIDA has been successfully tested and validated against experimental data from RFX-mod device, and numerical equilibria of an ITER-like device.  相似文献   
25.
Proceedings of the National Academy of Sciences, India Section B: Biological Sciences - Heavy metal concentrations in surface soils of Reserved Forests (RFs) have a significant impact on...  相似文献   
26.
27.
Colorectal cancer (CRC) is the third most diagnosed cancer and the second leading cause of cancer-related mortality in the United States. Across the globe, people in the age group older than 50 are at a higher risk of CRC. Genetic and environmental risk factors play a significant role in the development of CRC. If detected early, CRC is preventable and treatable. Currently, available screening methods and therapies for CRC treatment reduce the incidence rate among the population, but the micrometastasis of cancer may lead to recurrence. Therefore, the challenge is to develop an alternative therapy to overcome this complication. Nanotechnology plays a vital role in cancer treatment and offers targeted chemotherapies directly and selectively to cancer cells, with enhanced therapeutic efficacy. Additionally, nanotechnology elevates the chances of patient survival in comparison to traditional chemotherapies. The potential of nanoparticles includes that they may be used simultaneously for diagnosis and treatment. These exciting properties of nanoparticles have enticed researchers worldwide to unveil their use in early CRC detection and as effective treatment. This review discusses contemporary methods of CRC screening and therapies for CRC treatment, while the primary focus is on the theranostic approach of nanotechnology in CRC treatment and its prospects. In addition, this review aims to provide knowledge on the advancement of nanotechnology in CRC and as a starting point for researchers to think about new therapeutic approaches using nanotechnology.  相似文献   
28.
Maternal and Child Health Journal - Early life exposures can have an impact on a child’s developmental trajectory and children born late preterm (34–36&nbsp;weeks gestational age)...  相似文献   
29.
30.
ABSTRACT

Objective: Dry eye is reported to be associated with several neurological diseases. The aim of this study is to evaluate the patients with hemiplegia after stroke for dry eye and compare their results with a control group.

Materials and methods: Forty-five patients with hemiplegia and 45 individuals as the control group were included in the study. Tear function tests (Schirmer and tear breakup time) and a dry eye questionnaire for dry eye symptoms (ocular surface disease index) were performed and the results of the two groups were compared.

Results: Schirmer test results were significantly lower in the post-stroke hemiplegia group compared to the control group (11.3 ± 8.2 mm and 20.6 ± 11.6 mm, respectively, p < .001). Tear breakup time results were significantly lower in the post-stroke hemiplegia group compared to the control group (7.9 ± 3.1 s and 12.1 ± 4.3 s, respectively, p < .001). Ocular surface disease index scores were not significantly different between hemiplegia and control groups (21.6 ± 20.0 and 19.8 ± 13.9, respectively, p = .635). Schirmer scores lower than 10 mm (60% and 30%, p < .001) and tear breakup time results lower than 10 s (65.6% and 28.9%, p < .001) were also higher in the hemiplegia group compared to control group.

Conclusion: We found lower Schirmer test and tear breakup time results and similar OSDI scores in hemiplegia patients compared to controls. Hemiplegia patients may have dry eye without typical symptoms. This should be taken into consideration in the follow-up and rehabilitation of post-stroke hemiplegia patients.  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