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   445705篇
  免费   28649篇
  国内免费   2945篇
耳鼻咽喉   6362篇
儿科学   10866篇
妇产科学   12300篇
基础医学   61600篇
口腔科学   14751篇
临床医学   36020篇
内科学   90610篇
皮肤病学   9674篇
神经病学   32983篇
特种医学   16296篇
外国民族医学   83篇
外科学   71298篇
综合类   10321篇
现状与发展   1篇
一般理论   74篇
预防医学   22908篇
眼科学   10862篇
药学   35394篇
  1篇
中国医学   2341篇
肿瘤学   32554篇
  2021年   3710篇
  2019年   3848篇
  2018年   6115篇
  2017年   4738篇
  2016年   5073篇
  2015年   5607篇
  2014年   7641篇
  2013年   10332篇
  2012年   13665篇
  2011年   13963篇
  2010年   8456篇
  2009年   7819篇
  2008年   12423篇
  2007年   13637篇
  2006年   13311篇
  2005年   12449篇
  2004年   11653篇
  2003年   11214篇
  2002年   10651篇
  2001年   29970篇
  2000年   30460篇
  1999年   25179篇
  1998年   5776篇
  1997年   4758篇
  1996年   4296篇
  1995年   3912篇
  1994年   3492篇
  1993年   3173篇
  1992年   17155篇
  1991年   15836篇
  1990年   15235篇
  1989年   15007篇
  1988年   13559篇
  1987年   13008篇
  1986年   12004篇
  1985年   11186篇
  1984年   7649篇
  1983年   6178篇
  1982年   3082篇
  1979年   6074篇
  1978年   3769篇
  1977年   3318篇
  1975年   3032篇
  1974年   3511篇
  1973年   3291篇
  1972年   3241篇
  1971年   3146篇
  1970年   2851篇
  1969年   2885篇
  1968年   2585篇
排序方式: 共有10000条查询结果,搜索用时 78 毫秒
91.
92.
93.
94.
95.
96.
This paper describes a study to capture the key roles and activities of nephrology nurses across different countries in Europe. The concept of the study and the need to clarify the activities of the nephrology nurse arose as part of a larger study to develop the European Practice Database (EPD) (1). The Research Board (EDTNA/ERCA) needed to identify key questions that would detect significant differences in the role and responsibilities of nephrology nurses in different countries and monitor the evolution over time of nephrology nursing practice in Europe. It was therefore appropriate to devise a separate small study to generate evidence based questions for the EPD and confirm the reliability and usefulness of the information captured.  相似文献   
97.
Conclusion  Several quality-control measures take place before (patient and camera preparation) and during SPECT acquisition to achieve high-quality images. Not uncommonly, technologists and physicians are left with suboptimal images that have to be addressed to reach the “right answer” for patient diagnosis and hence management. In many cases patients may be reimaged, especially if the problem is detected early, but in other cases either the patient has left the nuclear laboratory or there is an inevitable problem that, even with reimaging, will not be resolved. In these situations the technologist and physician have to seek the available techniques to obtain the best images possible. These resources are discussed in this issue as an aid in quality control to obtain the best possible images.  相似文献   
98.
Salvage of a failed valgus osteotomy for nonunion of an unstable pertrochanteric fracture is reported. A valgus intertrochanteric osteotomy was performed for a failed sliding hip screw fixation of an unstable pertrochanteric fracture at another institution. Four months following osteotomy, the fracture was still un-united with two distal screws of the hip plate broken and a coxa vara deformity. Reconstruction was performed with a nine-hole 95° angle blade plate and cancellous bone graft, because the insufficient fixation of the distal fragment was considered to be the main reason for failure. The osteotomy was healed at six months post-surgery and the patient reported complete resolution of symptoms. Intertrochanteric valgus osteotomy is an effective procedure for mal-union and non-union of pertrochanteric fracture but stable fixation is required for a good result. The blade of the angle plate offers good purchase of the proximal fragment and secures it under rotational and bending stresses. We recommend that distal fragments should be fixed with at least seven cortices for this type of osteotomy.  相似文献   
99.
100.
OBJECTIVES: The aim of this study is to evaluate the effect of ZnSO(4) addition to a conventional glass ionomer and a resin-modified glass ionomer on solubility, flexural strength, zinc and fluoride (F) release, and Streptococcus mutans growth inhibition. METHODS: 5 or 10% ZnSO(4) was added to Vitremer and Ketac-Fil powders. Solubility test was performed based on ISO 7489. Flexural strength was determined by 3-point bending test based on ISO 4049. Zn release/uptake was determined by atomic emission spectrometry; F release/uptake was measured using a F-specific electrode. Both release measurements were performed for 15 d before and 15 d after recharging. Antibacterial test was conducted according to agar plate methods against S. mutans, by measuring the inhibition halos in 1-h and 15-d specimens. Data were analyzed by ANOVA. RESULTS: Solubility increased with higher ZnSO(4) content, but remained below the ISO 7489 limit. Flexural strength was not affected by ZnSO(4) addition, and Vitremer performed better than Ketac-Fil. The control materials released no zinc. Vitremer with 10% ZnSO(4) released the highest amount of zinc. Fluoride release was similar for Ketac-Fil and Vitremer. In both cases, the highest amounts were released in the first 24 h. The growth inhibition halo of S. mutans was similar for both materials with highest content of ZnSO(4) and occurred only with 1-h specimens. SIGNIFICANCE: Zinc addition decreased microorganisms growth and improved fluoride release, without significantly affecting the materials' flexural strength and solubility.  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