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   4279859篇
  免费   351003篇
  国内免费   15362篇
耳鼻咽喉   60913篇
儿科学   132948篇
妇产科学   111846篇
基础医学   655069篇
口腔科学   118786篇
临床医学   387754篇
内科学   775569篇
皮肤病学   103254篇
神经病学   366351篇
特种医学   170660篇
外国民族医学   912篇
外科学   652073篇
综合类   126411篇
现状与发展   23篇
一般理论   2580篇
预防医学   362202篇
眼科学   100456篇
药学   301981篇
  28篇
中国医学   11472篇
肿瘤学   204936篇
  2021年   55812篇
  2020年   35550篇
  2019年   58656篇
  2018年   73290篇
  2017年   55954篇
  2016年   62257篇
  2015年   75617篇
  2014年   110360篇
  2013年   175710篇
  2012年   117560篇
  2011年   120569篇
  2010年   122931篇
  2009年   126125篇
  2008年   107662篇
  2007年   114180篇
  2006年   123700篇
  2005年   118797篇
  2004年   119733篇
  2003年   110479篇
  2002年   101066篇
  2001年   154326篇
  2000年   150511篇
  1999年   139562篇
  1998年   71272篇
  1997年   67743篇
  1996年   65624篇
  1995年   61489篇
  1994年   55566篇
  1993年   51601篇
  1992年   103583篇
  1991年   98954篇
  1990年   94051篇
  1989年   91690篇
  1988年   85316篇
  1987年   83774篇
  1986年   79469篇
  1985年   77918篇
  1984年   65944篇
  1983年   58861篇
  1982年   48142篇
  1981年   44878篇
  1980年   42166篇
  1979年   57830篇
  1978年   47031篇
  1977年   41594篇
  1976年   38656篇
  1975年   37852篇
  1974年   42420篇
  1973年   40548篇
  1972年   38015篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
991.
Tissue specimens from the large bowel of 18 patients with long-standing slow transit constipation were investigated to determine the distribution and density of several neuropeptides and amines in the enteric nerve system, and also of endocrine cells in comparison to normal individuals. CGRP (calcitonin gene-related peptide), galanin, glucagon, GRP (gastrin-releasing peptide), metenkephalin, motilin, neuropeptide Y (NPY), PACAP, peptide YY (PYY), serotonin, somatostatin, substance P and VIP were studied by immunohistochemistry. Tissue concentrations of VIP, substance P and galanin were also measured by radioimmunoassay. Significantly increased VIP, SP and galanin contents were found in specimens from the ascending colon. Levels of VIP and galanin were also increased in the transverse colon. Immunohistochemistry revealed only marginal changes with an increased density of PACAP nerve fibres in the smooth muscle and of VIP and PACAP nerves in the myenteric plexus of the transverse colon. In the descending colon substance P and NPY immunoreactivity were also increased in the myenteric plexus while the density of VIP nerve fibres was reduced in the mucosa/submucosa. The frequency of PYY-containing cells and the 5-HT-containing cells in the ascending colon was significantly increased in the constipated patients.  相似文献   
992.
993.
Purpose: To assess the accuracy of intraarterial measurement of transstenotic pressure gradients for the detection of hemodynamically suboptimal iliac angioplasty. Methods: In 14 patients, referred for diagnostic angiography, mean pressure gradients in the aorta and iliac artery were obtained twice, using a double-sensor pressure catheter. Additional iliac measurements were performed during pharmacologically induced flow augmentation. Repeatability was assessed by calculation of the mean difference plus standard deviation (MD ± SD) and repeatability coefficient (2 × SD). These results were extrapolated to 137 iliac angioplasty procedures with secondary stenting where there was a residual pressure gradient > 10 mmHg. Results: MD ± SD for repeated measurements at rest and during flow augmentation were 0 ± 2 mmHg and 1 ± 3 mmHg, respectively. Repeatability coefficients were 3 and 6 mmHg. Mean pressure gradients after hemodynamically insufficient angioplasty were 8 ± 7 mmHg at rest and 17 ± 5 mmHg following vasodilatation. Inaccurate pressure recordings may have led to inappropriate stent placement in less than 2.5%, and inappropriate denial of stent placement in less than 5% of the lesions. Conclusion: Variability of intraarterial pressure measurements has little consequence in the detection of hemodynamically significant stenosis after angioplasty. Received: 0/00/00/Accepted: 0/00/00  相似文献   
994.
995.
996.
997.
998.
999.
OBJECTIVE: To describe Ontario emergency physicians' knowledge of colleagues' sexual involvement with patients and former patients, their own personal experience of such involvement, and their attitudes toward postvisit relationships. DESIGN: Mailed survey. SETTING: Ontario. PARTICIPANTS: Emergency physicians practising in Ontario. RESULTS: Of 974 eligible mailed surveys, 599 (61.5%) were returned. Of these respondents, 52 (8.7%) reported being aware of a colleague in emergency practice who had been sexually involved with a patient or former patient. When describing their own behaviour, 37 respondents (6.2%) reported sexual involvement with a former patient. However, of this group, only 9 (25.0%) had met the patient in an emergency department. Thus, of the total number of respondents, only 1.5% (9/599) reported sexual involvement arising out of an emergency department visit. Most respondents (82.4%) agreed that it is inappropriate behaviour to ask a patient for a date after an emergency assessment and before the patient's departure, and 66.4% felt that it is inappropriate to contact the patient after discharge. However, only 10.6% believed it to be unacceptable to request a social meeting after encountering a patient previously cared for in the emergency department in a nonprofessional setting. Most respondents (96.5%) did not believe that sexual involvement could ever be therapeutic for the patient. However, only 66% felt that it was always an abuse of power and 62.4% supported zero tolerance of all sexual involvement between physicians and patients. CONCLUSIONS: Vague regulatory guidelines currently in place have failed to dispel confusion regarding what is acceptable social behaviour for physicians providing emergency care. Our results support the need for clarification, and suggest a basis for guidelines that would be acceptable to the emergency medical community: that an emergency visit should not form the basis for the initiation of personal or sexual relationships, yet neither should it preclude their development in nonmedical settings.  相似文献   
1000.
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