首页 | 官方网站   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   7099篇
  免费   590篇
  国内免费   34篇
医药卫生   7723篇
  2023年   38篇
  2022年   26篇
  2021年   128篇
  2020年   96篇
  2019年   153篇
  2018年   164篇
  2017年   132篇
  2016年   131篇
  2015年   148篇
  2014年   237篇
  2013年   447篇
  2012年   505篇
  2011年   487篇
  2010年   287篇
  2009年   272篇
  2008年   415篇
  2007年   514篇
  2006年   458篇
  2005年   418篇
  2004年   402篇
  2003年   384篇
  2002年   344篇
  2001年   64篇
  2000年   53篇
  1999年   83篇
  1998年   95篇
  1997年   88篇
  1996年   58篇
  1995年   68篇
  1994年   62篇
  1993年   39篇
  1992年   53篇
  1991年   45篇
  1990年   40篇
  1989年   52篇
  1988年   57篇
  1987年   50篇
  1986年   47篇
  1985年   47篇
  1984年   44篇
  1983年   47篇
  1982年   45篇
  1981年   42篇
  1980年   36篇
  1979年   19篇
  1978年   20篇
  1977年   20篇
  1975年   18篇
  1974年   25篇
  1973年   24篇
排序方式: 共有7723条查询结果,搜索用时 134 毫秒
21.
22.
Within the context of the new medical methodology of evidence-based medicine, the ethical issues of making the randomized, placebo-controlled, clinical trial part of the matrix of surgical procedure evaluation are discussed. Surgical trials with alternative research design less rigorous than the double-blind, placebo-controlled, randomized trial leave the alternative: implementing surgical procedures based on anecdotal evidence and weaker scientific research. The conundrum of these clinical trials, as it relates to the evaluation of surgical procedures, is that it appears to confound some of the fundamental ethical principles of beneficence and nonbeneficence. The placebo effect with surgery is so strong that "sham surgery" within the clinical trial context is essential and an appropriate component of the ethics of clinical research. A discussion of these issues is presented.  相似文献   
23.
Abstract A previous study of the sensitivity and accuracy of a standardized radiographic technique for the disclosure of root cavities in a cadaver material indicated that it was not possible to perceive small artificial “resorption” cavities. Using the same material, the aim of the present study was to evaluate whether the use of subtraction radiography would improve the detection of root cavities. In an autopsy material of five mandibular blocks each containing two premolars, small, medium, and large cavities were drilled in the cervical, middle, and apical thirds of the proximal and oral root surfaces. Each jaw block was radiographed before (B) and after (A) cavity preparation with three different exposure times resulting in light, medium, and dark film densities. The radiographs were digitized. Digital subtraction was performed between the A- and B images of varying densities by a computer program developed for dental subtraction radiography. Conventional and reverse contrast modes of the subtraction image were assessed independently by four observers. The results showed small inter- and intraobserver differences in diagnostic accuracy for assessment of total number of root cavities. Original film density did not influence the diagnostic performance in the resulting subtraction image. Contrast mode in the subtraction image influenced diagnostic performance as the majority of observers did best with the reverse contrast mode (p<0.05). Some of the small root cavities were disclosed by the subtraction technique, but overall accuracy was not increased compared to conventional radiography.  相似文献   
24.
25.
26.
Regional anaesthesia provides many advantages and can be practised safely in ambulatory surgery. It provides better postoperative pain control, avoids many complications associated with general anaesthesia and shortens recovery time. However, extra time required, associated complications and acceptance of patients are the factors of concern in practising regional anaesthesia in an ambulatory setting. This review will discuss various regional anaesthesia techniques suitable for outpatients.  相似文献   
27.
PURPOSE: Following ambulatory surgery, long-acting analgesics may provide advantages over short-acting analgesics. This study compared controlled-release codeine (CC) and acetaminophen plus codeine (A/C; 300 mg/30 mg) for pain control in the 48-hr period following laparoscopic cholecystectomy. METHODS: Eligible patients were randomized to CC or A/C in a double-blind, double-dummy parallel group study. Unrelieved pain in hospital was treated with fentanyl i.v. bolus. Pain [100 mm visual analogue scale (VAS)] was assessed before the first dose of medication; at 0.5, one, two, three, and four hours post-dose; at discharge; and three times a day for 48 hr. Adverse events were recorded and measures of patient satisfaction were assessed at the end of the study. RESULTS: Eighty-four patients were enrolled in the study; 42 patients in each group. There were no statistically significant differences between CC and A/C treatment. Mean VAS baseline pain was similar in both groups (P = 0.49) and there was no significant difference in the time to onset of analgesia (P = 0.17). At 0.5 hr, the mean VAS pain score was significantly reduced from baseline in both groups (P = 0.0001). The VAS pain scores at discharge were reduced 59% and 56% from baseline, respectively (P = 0.61). There was no difference between treatments in the incidence of adverse events and patients reported similar levels of satisfaction. CONCLUSIONS: Controlled-release codeine provides an equivalent onset of analgesia, reduction in postoperative pain, and level of patient satisfaction, to acetaminophen plus codeine, over 48 hr following cholecystectomy, with the advantage of less frequent dosing.  相似文献   
28.
29.
A survey of shelters serving women in Chicago (N = 43) identified admission criteria, policies and services, estimated the number of homeless women in childbearing years served by the shelters, the number who were pregnant or mothers with children, and identified unmet health needs and health services provided. The majority (64%) of the women using shelters were African American and there was great variability in shelter policies. Women with male children more than seven years old, pregnant women and substance abusers were less likely to be admitted.  相似文献   
30.
BACKGROUND: Epidemiological studies suggest that environmental adversity can alter parental care and thus influence child development. We addressed the question of whether stressors can directly affect parental behavior using a rodent model of stable, individual differences in maternal behavior. METHODS: Lactating rat mothers were characterized as high or low in pup-directed licking/grooming (LG) behavior, rebred, and subjected to 7 days of intermittent stress or control conditions during gestation. Female rats were mated a third time without any subsequent intervention. Maternal behavior, oxytocin receptor (OTR) binding, and offspring behavior were examined. RESULTS: Stress reduced OTR levels and pup LG of high LG mothers to levels comparable with those of low LG mothers. The adult offspring of the gestational stress/high LG mothers resembled those of low LG mothers on behavioral measures of anxiety and maternal behavior, as well as OTR levels. The results of the third mating revealed an enduring effect of gestational stress on both mother and offspring maternal LG. CONCLUSIONS: These findings suggest that stress can directly alter maternal care through the neuroendocrine systems that normally regulate this behavior. Thus, the effects of environmental adversity can be transmitted across generations through a nongenomic mechanism involving maternal care.  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-23

京公网安备 11010802026262号