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   211810篇
  免费   2827篇
  国内免费   204篇
耳鼻咽喉   1453篇
儿科学   7154篇
妇产科学   3351篇
基础医学   21428篇
口腔科学   2638篇
临床医学   14599篇
内科学   39940篇
皮肤病学   1534篇
神经病学   18900篇
特种医学   10281篇
外科学   34948篇
综合类   2494篇
一般理论   1篇
预防医学   19167篇
眼科学   3361篇
药学   12232篇
中国医学   729篇
肿瘤学   20631篇
  2023年   166篇
  2022年   365篇
  2021年   642篇
  2020年   379篇
  2019年   478篇
  2018年   22410篇
  2017年   17794篇
  2016年   19973篇
  2015年   1524篇
  2014年   1623篇
  2013年   1807篇
  2012年   8514篇
  2011年   22657篇
  2010年   19754篇
  2009年   12377篇
  2008年   20990篇
  2007年   23214篇
  2006年   2228篇
  2005年   3996篇
  2004年   5063篇
  2003年   6030篇
  2002年   4178篇
  2001年   1637篇
  2000年   1813篇
  1999年   1450篇
  1998年   760篇
  1997年   659篇
  1996年   492篇
  1995年   473篇
  1994年   434篇
  1993年   398篇
  1992年   919篇
  1991年   860篇
  1990年   924篇
  1989年   820篇
  1988年   800篇
  1987年   701篇
  1986年   667篇
  1985年   653篇
  1984年   431篇
  1983年   364篇
  1982年   208篇
  1981年   166篇
  1980年   203篇
  1979年   334篇
  1978年   232篇
  1977年   165篇
  1974年   241篇
  1973年   162篇
  1972年   172篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
11.
12.
The use of parenteral nutrition is becoming more widespread. The need for individualized parenteral nutrition solutions in pediatric patients makes the ordering and preparation of these solutions more complex and error-prone. A computer program is described which performs comprehensive management of parenteral nutrition by assisting in accurately ordering and preparing parenteral nutrition solutions. It also performs extensive error-checking and provides additional nutritional information. Data base management is also a feature which permits future large scale analysis of parenteral nutrition data for research purposes. This program, designed to run on a personal computer, is very comprehensive, yet flexible and user-friendly.  相似文献   
13.
Contemporary discourse contains numerous examples of use of the concept of culture by social and behavioral scientists. Simple reification, where the speaker makes culture into a thing capable of action exemplifies one usage in public discourse. Some quantitative social scientists attempt to characterize people’s cultural identities by means of a single categorical variable, which often “lumps” people into categories such as “Hispanic” or “Black” that in fact have numerous culturally bounded subcategories. Approaches that emphasize cultural process are preferable to those who attempt to categorize; more complex measures of acculturation help investigators to make convincing analyses of circumstances in which health disparities occur. Examples in which investigators make appropriate use of cultural characterizations demonstrate their utility in investigating health disparities in Haitian American women, injecting and noninjecting drug users, Hispanic youth, and adult Hispanics at risk of HIV infection. Focus on culture in the study of health disparities can identify entanglements between structural factors such as poverty and lack of education and cultural factors such as beliefs about health. Qualitative methods coupled with quantitative methods have great potential to improve investigators’ grasp of cultural nuance while capturing the distribution of qualitatively derived behaviors.  相似文献   
14.
15.
The specific characteristics of genetic data lead to ethical-legal conflicts in the framework of genetic diagnosis. Several international organisations, including UNESCO and the Council of Europe, have enacted rules referring to the use of genetic information. This paper discusses possible legal and ethical criteria that could be used in genetic testing.  相似文献   
16.
17.
PURPOSE: This study evaluated the bone volume, height, and width that can be obtained in alveolar ridge augmentation using titanium mesh and autogenous bone particles in patients with cleft lip/palate. PATIENTS AND METHODS: Subjects were 15 patients with cleft lip/palate requiring tertiary bone graft for implant therapy. Computed tomography (CT) scans were taken before removing the mesh, from 1 to 21 months after bone grafting. Forty-three reconstructed images corresponding to the positions for implant placement were selected for this study. The percent defect filled with bone (%BONE), defined as the percentage of newly formed bone in the space created by the mesh, was measured for image analyses. In linear analyses, 4 parameters were used: increased bone height (IBH), percent increased bone height (%IBH), increased bone width (IBW), and percent increased bone width (%IBW). Factors influencing the quantitative data and the clinical courses of placed implants were also explored. RESULTS: The average %BONE was 91.1%. IBH averaged 4.4 mm, whereas %IBH averaged 88.5%. IBW averaged 4.6 mm, whereas %IBW averaged 86.4%. Little correlation was present between the quantitative data and patient age, or time interval. A significant correlation was identified between the data for span of the grafted area and %BONE (correlation coefficient value = -0.36). However, the diminishing rate was very low. No implants were lost postoperatively. CONCLUSIONS: Alveolar ridge augmentation with titanium mesh and autogenous bone particles from the anterior iliac crest has very high predictability as a preimplant procedure in patients with cleft lip/palate.  相似文献   
18.
The depletion of proteoglycans in cartilage matrix is the beginning of cartilage breakdown. Prostaglandins and related compounds might play an important role in inhibition of cartilage metabolism under arthritic conditions. Prostaglandin endoperoxides, intermediate metabolites of arachidonic acid, are more potent chemical mediators than prostaglandins, but their action can only be demonstrated in cartilage co-incubated with synovial tissue, because they are short-lived and active only within a small restricted space. Human rheumatoid synovialis highly inhibited sulfation of cartilage matrix co-incubated. The inhibition of cartilage metabolism was released by indomethacin added to the co-incubating system, showing its responsiveness to indomethacin. The magnitude of inhibition was time-dependent and substantially greater than that by prostaglandin in cell-free rheumatoid synovial culture media. The results suggest a possible involvement of prostaglandin endoperoxides in potent inhibition of cartilage metabolism under arthritic conditions.  相似文献   
19.
For persons battling HIV/AIDS a stable place to live may decide the length and quality of life itself. It is nearly impossible for a person on the streets to engage in a needed continuous AIDS treatment regimen when the very basic question of where that person will rest his or her head when darkness comes in just a few hours is unresolved. When danger lurks on the streets, when cold numbs the limbs, when tiredness overwhelms the mind, when fear breaks the spirit, a place to call home would make all the difference.  相似文献   
20.
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