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   252104篇
  免费   17870篇
  国内免费   1130篇
耳鼻咽喉   2788篇
儿科学   6495篇
妇产科学   4599篇
基础医学   32972篇
口腔科学   4565篇
临床医学   25330篇
内科学   53606篇
皮肤病学   3384篇
神经病学   24276篇
特种医学   8398篇
外国民族医学   11篇
外科学   38481篇
综合类   3457篇
一般理论   318篇
预防医学   21406篇
眼科学   6563篇
药学   16971篇
  6篇
中国医学   361篇
肿瘤学   17117篇
  2023年   1341篇
  2022年   2411篇
  2021年   5440篇
  2020年   3262篇
  2019年   5300篇
  2018年   5951篇
  2017年   4471篇
  2016年   4958篇
  2015年   5828篇
  2014年   8604篇
  2013年   11796篇
  2012年   18017篇
  2011年   18902篇
  2010年   10577篇
  2009年   9429篇
  2008年   16594篇
  2007年   17449篇
  2006年   17302篇
  2005年   17277篇
  2004年   16190篇
  2003年   15040篇
  2002年   14058篇
  2001年   2102篇
  2000年   1600篇
  1999年   2329篇
  1998年   3070篇
  1997年   2563篇
  1996年   2190篇
  1995年   2104篇
  1994年   1750篇
  1993年   1573篇
  1992年   1260篇
  1991年   1150篇
  1990年   999篇
  1989年   975篇
  1988年   968篇
  1987年   948篇
  1986年   951篇
  1985年   965篇
  1984年   1223篇
  1983年   1126篇
  1982年   1367篇
  1981年   1313篇
  1980年   1147篇
  1979年   705篇
  1978年   748篇
  1977年   636篇
  1976年   585篇
  1975年   469篇
  1974年   473篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
41.
The aim of the current research project was to explore the possibilities of combining pressurized carbon dioxide with hot stage extrusion during manufacturing of solid dispersions of itraconazole and polyvinylpyrrolidone-co-vinyl acetate 64 (PVP-VA 64) and to evaluate the ability of the pressurized gas to act as a temporary plasticizer as well as to produce a foamed extrudate. Pressurized carbon dioxide was injected into a Leistritz Micro 18 intermeshing co-rotating twin-screw melt extruder using an ISCO 260D syringe pump. The physicochemical characteristics of the extrudates with and without injection of carbon dioxide were evaluated with reference to the morphology of the solid dispersion and dissolution behaviour and particle properties. Carbon dioxide acted as plasticizer for itraconazole/PVP-VA 64, reducing the processing temperature during the hot stage extrusion process. Amorphous dispersions were obtained and the solid dispersion was not influenced by the carbon dioxide. Release of itraconazole from the solid dispersion could be controlled as a function of processing temperature and pressure. The macroscopic morphology changed to a foam-like structure due to expansion of the carbon dioxide at the extrusion die. This resulted in increased specific surface area, porosity, hygroscopicity and improved milling efficiency.  相似文献   
42.
This paper reports the proceedings of the discussion panel assigned to look at clinical aspects of quality in emergency medicine. One of the seven stated objectives of the Academic Emergency Medicine consensus conference on quality in emergency medicine was to educate emergency physicians regarding quality measures and quality improvement as essential aspects of the practice of emergency medicine. Another topic of interest was a discussion of the value of information technology in facilitating quality care in the clinical practice of emergency medicine. It is important to note that this is not intended to be a comprehensive review of this extensive topic, but instead is designed to report the discussion that occurred at this session of the consensus conference.  相似文献   
43.
44.
45.
46.
47.
The purpose of this study was to provide, in a large number of patients, comprehensive Doppler echocardiographic assessment of normal St Jude Medical mitral valve prosthesis function using Doppler-derived hemodynamic variables, including the mitral valve prosthesis-to-left ventricular outflow tract time-velocity integral ratio and prosthesis performance index. The pressure half-time was less than 130 milliseconds in all patients, and all but one patient had either a peak early mitral diastolic velocity of 2 m/s or less or a mitral valve prosthesis-to-left ventricular outflow tract time-velocity integral ratio of less than 2.2. There was a significant (P < .001) negative correlation between the prosthesis performance index and prosthesis size. This negative correlation suggests that there is more efficient use of the in vitro geometric orifice area with smaller prostheses.  相似文献   
48.
OBJECTIVE: This study was designed to investigate potential areas of practice for the clinical laboratory scientist (CLS) and to propose a graduate curriculum to prepare the practitioner for an advanced level of practice. DESIGN: Meta-analysis of PharmD, physician assistant, physical therapy, and nurse practitioner curricula focusing on academic and clinical advanced practice was used to develop an educational model and curriculum for a professional doctorate in clinical laboratory science (CLS). MAIN OUTCOME MEASURE: (1) New educational model for CLS advanced practice; (2) A proposed curriculum for a Doctorate of Clinical Laboratory Science degree. RESULTS: A new curriculum model was adapted from established healthcare educational models. CONCLUSION: Although there is a need for a baccalaureate degree in CLS there is also a role for expanded education and responsibilities for CLS practitioners. The CLS Advanced Practitioner design focuses on moving students from the baccalaureate level to the doctoral level and prepares the individual to become an integral part of the healthcare team.  相似文献   
49.
50.
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