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   2548456篇
  免费   199802篇
  国内免费   3965篇
耳鼻咽喉   36284篇
儿科学   86540篇
妇产科学   72098篇
基础医学   362665篇
口腔科学   72834篇
临床医学   225715篇
内科学   498632篇
皮肤病学   54839篇
神经病学   204278篇
特种医学   101699篇
外国民族医学   1064篇
外科学   387754篇
综合类   59931篇
现状与发展   4篇
一般理论   866篇
预防医学   196870篇
眼科学   58527篇
药学   191349篇
  5篇
中国医学   4747篇
肿瘤学   135522篇
  2018年   24822篇
  2016年   21138篇
  2015年   24206篇
  2014年   33627篇
  2013年   51591篇
  2012年   70107篇
  2011年   74248篇
  2010年   44177篇
  2009年   42054篇
  2008年   71074篇
  2007年   75434篇
  2006年   76319篇
  2005年   74309篇
  2004年   72773篇
  2003年   69949篇
  2002年   68565篇
  2001年   119641篇
  2000年   124143篇
  1999年   105408篇
  1998年   28978篇
  1997年   26267篇
  1996年   26554篇
  1995年   25631篇
  1994年   24172篇
  1993年   22620篇
  1992年   86022篇
  1991年   83890篇
  1990年   82098篇
  1989年   78765篇
  1988年   73044篇
  1987年   71957篇
  1986年   67916篇
  1985年   65469篇
  1984年   49066篇
  1983年   42039篇
  1982年   24658篇
  1981年   22185篇
  1980年   20499篇
  1979年   45983篇
  1978年   32078篇
  1977年   27047篇
  1976年   25461篇
  1975年   27170篇
  1974年   32717篇
  1973年   31529篇
  1972年   28994篇
  1971年   26876篇
  1970年   24980篇
  1969年   23198篇
  1968年   21193篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
991.
Physiologic assessment of diseases of the motor unit from the anterior horn cells to the muscles relies on a combination of needle electromyography (EMG) and nerve conduction studies (NCS). Both require a unique combination of knowledge of peripheral nervous system anatomy, physiology, pathophysiology, diseases, techniques, and electricity is necessary. Successful, high‐quality, reproducible EMG depends on the skills of a clinician in patient interaction during the physical insertion and movement of the needle while recording the electrical signals. These must be combined with the skill of analyzing electric signals recorded from muscle by auditory pattern recognition and semiquantitation. 10 , 52 This monograph reviews the techniques of needle EMG and waveform analysis and describes the types of EMG waveforms recorded during needle EMG. © 2009 Wiley Periodicals, Inc. Muscle Nerve 39: 244–270, 2009  相似文献   
992.
993.
We provide further evidence for the two-factor structure of the 9-item Academic Expectations Stress Inventory (AESI) using confirmatory factor analysis on a sample of 289 Canadian adolescents and 310 Singaporean adolescents. Examination of measurement invariance tests the assumption that the model underlying a set of scores is directly comparable across groups. This study also examined the cross-cultural validity of the AESI using multigroup confirmatory factor analysis across both the Canadian and Singaporean adolescent samples. The results suggested cross-cultural invariance of form, factor loadings, and factor variances and covariances of the AESI across both samples. Evidence of AESI's convergent and discriminant validity was also reported. Findings from t-tests revealed that Singaporean adolescents reported a significantly higher level of academic stress arising from self expectations, other expectations, and overall academic stress, compared to Canadian adolescents. Also, a larger cross-cultural effect was associated with academic stress arising from other expectations compared with academic stress arising from self expectations.  相似文献   
994.
In recent years, the surgical profession has attempted to incorporate into clinical practice certain techniques that the airline industry has used to improve safety. These mechanisms have proven to be valuable components of our efforts to ensure that surgical patients receive safe, high-quality care. However, as the authors of “Cost and workforce implications of subjecting all physicians to aviation industry work hour restrictions” note, it would be a mistake to extend aviation's work-hour restrictions to medicine, particularly to resident training programs.  相似文献   
995.
996.
Background: In elderly patients, opioids may cause prominent postoperative sedation and respiratory depression. We evaluated the influence of age on the effects of opioids and plasma concentrations of fentanyl and oxycodone in cardiac surgery patients.
Methods: Thirty (≥75 years, gender M9/F21) and 20 (≤60 years, gender M20/F0) patients scheduled to undergo cardiac surgery. A standard anesthesia with fentanyl as an opioid was used. Fentanyl plasma concentrations were measured at the end of surgery and 2 h later. After tracheal extubation, when the pain intensity was at least moderate, blood samples for fentanyl and oxycodone plasma concentration measurements were taken. Thereafter, oxycodone hydrochloride 0.05 mg/kg i.v. was administered. After 15 and 45 min, pain intensity, sedation and oxycodone plasma concentration were determined. This test protocol was repeated twice.
Results: The elderly had a higher plasma concentration of fentanyl at the end of surgery than younger patients (5.7±2.2 vs. 3.8±1.2 ng/ml, P =0.001). The plasma concentrations of oxycodone were comparable between the groups. The interval between the second and the third oxycodone dose was longer in the elderly patients ( P =0.036). Pain intensity on the verbal rating scale was lower at the 45-min assessment point after all three oxycodone test doses ( P =0.008) and sedation scores were significantly higher after the third dose in the elderly patients ( P =0.035).
Conclusions: In elderly patients, the plasma concentration of fentanyl was higher but plasma levels of oxycodone were at a similar level compared with middle-aged patients. However, the elderly patients had less pain and were more sedated after doses of oxycodone.  相似文献   
997.

Background:

The results of a pilot colorectal cancer screening programme by biennial immunochemical faecal occult blood test (FOBT) are reported.

Methods:

All residents aged between 50 and 69 years in the Italian province of Lecco were invited to have a FOBT. Those with a positive result were offered colonoscopy. FOBT uptake and compliance with colonoscopy were assessed. Detection rate and positive predictive value (PPV) for cancer and adenoma were calculated. Tumour stages were compared between screen‐detected cancers and other colorectal cancers diagnosed within the target age group.

Results:

Some 38 693 (49·6 per cent) of 78 083 individuals had a FOBT and 2392 (6·2 per cent) had a positive result. Colorectal cancer was diagnosed in 4·6 per cent and advanced adenoma in 32·7 per cent. PPVs were 4·0 per cent for cancer, 28·1 per cent for advanced adenoma and 36·6 per cent for any adenoma. There was a significant difference in incidence of stage III/IV disease between screened and non‐screened cohorts. Compliance for colonoscopy was 92·0 per cent. Major determinants of compliance were age less than 59 years, female sex, high education level and non‐manual work.

Conclusion:

These results justify extension of colorectal cancer screening to other regions of Italy. Copyright © 2009 British Journal of Surgery Society Ltd. Published by John Wiley & Sons, Ltd.  相似文献   
998.
999.
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