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   1132054篇
  免费   77190篇
  国内免费   4767篇
耳鼻咽喉   15509篇
儿科学   35387篇
妇产科学   29571篇
基础医学   159876篇
口腔科学   30566篇
临床医学   101698篇
内科学   212714篇
皮肤病学   25082篇
神经病学   84169篇
特种医学   45367篇
外国民族医学   235篇
外科学   169791篇
综合类   30645篇
现状与发展   16篇
一般理论   277篇
预防医学   78368篇
眼科学   25834篇
药学   92310篇
  60篇
中国医学   5857篇
肿瘤学   70679篇
  2021年   10366篇
  2019年   9590篇
  2018年   13254篇
  2017年   10659篇
  2016年   11832篇
  2015年   13666篇
  2014年   18297篇
  2013年   25249篇
  2012年   34777篇
  2011年   36785篇
  2010年   21895篇
  2009年   20233篇
  2008年   33132篇
  2007年   35299篇
  2006年   35675篇
  2005年   33807篇
  2004年   31945篇
  2003年   30621篇
  2002年   29394篇
  2001年   61442篇
  2000年   62837篇
  1999年   52193篇
  1998年   13177篇
  1997年   11737篇
  1996年   11613篇
  1995年   10824篇
  1994年   9795篇
  1993年   9155篇
  1992年   38214篇
  1991年   36602篇
  1990年   36044篇
  1989年   34543篇
  1988年   31091篇
  1987年   30193篇
  1986年   28372篇
  1985年   26577篇
  1984年   19279篇
  1983年   16181篇
  1982年   8870篇
  1979年   17083篇
  1978年   11430篇
  1977年   10246篇
  1976年   8858篇
  1975年   10088篇
  1974年   11682篇
  1973年   11299篇
  1972年   10782篇
  1971年   10118篇
  1970年   9275篇
  1969年   8955篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
841.
842.
OBJECTIVE: To identify spatial patterns of changes in infant mortality rates and proportions of low-birth-weight live births observed in 1994. SETTING: Canada. SUBJECTS: Live births and infant deaths in Canada between 1987 and 1994. Data for Newfoundland were unavailable for 1987 through 1990. OUTCOME MEASURES: Annual infant mortality rates (crude and after excluding live newborns weighing less than 500 g); proportion of live births by low-birth-weight category (500-2499 g). RESULTS: Nova Scotia, New Brunswick, Quebec and Manitoba had lower crude and adjusted infant mortality rates in 1994 than in 1993. Newfoundland, Saskatchewan, Alberta and British Columbia had higher rates in 1994 than in 1993. The crude rate in Ontario was lower, and the adjusted rate higher, in 1994 than in 1993. A downward trend in the proportion of low-birth-weight live births was observed in Quebec (chi(2) for trend = 29.2, p < 0.01). Conversely, an upward trend was observed in Ontario (chi(2) for trend = 241.3, p < 0.01). However, the increase may have been due to data errors, especially in 1993 and 1994, involving truncation of ounces in 2 digits to 1 digit (e.g., 5 pounds 10 ounces became 5 pounds 1 ounce). CONCLUSIONS: Although the marginal increases in infant mortality observed in several provinces could be the result of random variation, future trends should be closely monitored. The proportion of low-birth-weight live births in Canada (excluding Ontario) appears to be stable, with Quebec showing significant reductions. The errors in data for Ontario need to be corrected before trends can be estimated for that province and for Canada as a whole.  相似文献   
843.
844.
Laparoscopic appendicectomy has been the subject of several encouraging reports, but has not as yet gained widespread acceptance. We present a series of 159 consecutive laparoscopic appendicectomies performed, over a 4 yr period, in both adults and children. We find the procedure as safe as its open counterpart, with patients fit to leave hospital within the same time period. Perforated appendices were amenable to this procedure, and the location of the appendix did not alter the outcome. Children responded as well as adults post-operatively. Obesity may be an indication for this form of treatment. Removal of displaced faecoliths associated with perforated appendicitis is a difficult technical problem in less than 5 per cent of patients.  相似文献   
845.
846.
Thoracic duct cyst in supraclavicular region.   总被引:1,自引:0,他引:1  
A 28-year-old female attended an outpatient clinic in October, 1989, because of a tumor in the left supraclavicular fossa, detected in a health examination. Following exploratory puncture of the tumor which yielded milky-white fluid, suggesting a cyst in the thoracic duct, she was admitted to our department. The cyst was unilocular measuring about 6 cm in diameter, and the fluid content was chyle-rich in lipids. Lymphography demonstrated a lymphatic structure adjacent to the lesion and scattered lymph vessels on the cyst surface. On November 16 the cyst was resected. A restiform structure was observed between the cyst and the thoracic duct, but the presence or absence of communication was unclear. The histological diagnosis was thoracic duct cyst. Thoracic duct cyst occurring in the cervical region is very rare. Our case may provide useful information as to its pathogenesis and the mode of retention of cyst fluid.  相似文献   
847.
848.
Forty chronic heloma durum (HD) were treated by electrodesiccation. The mean age of the subjects was 55 years (range 40–72). Effectiveness of treatment was assessed by measuring pain associated with the corn. The subject's tolerance to pain was determined using a 10 cm visual analogue scale. Six weeks postoperatively the mean pain scores were 72.9% lower (P < 0.01) than preoperative scores. Twelve months postoperatively the mean pain scores were 57.6% lower (P < 0.01) than the preoperative scores. Electrodesiccation was found to be successful in reducing the pain experienced from chronic digital and plantar heloma durum.  相似文献   
849.
In this study, the effect of combining anti-CD4 monoclonal antibody (mAb) and cyclosporin (CyA) therapy at the time of transplantation was examined. A mouse cardiac allograft model was used. Anti-CD4 mAb administered perioperatively induces long-term survival. The addition of a short course of CyA given subcutaneously in a regimen of either a high-dose treatment or a standard dose treatment to the anti-CD4 mAb treatment protocol did not have a detrimental effect on graft survival. Despite having no significant effect on graft survival, the addition of CyA to the treatment protocol did result in a significant decrease in the level of IL-2 present in the hearts 7 days after transplantation. The decrease in IL-2 production was directly related to the presence of CyA in vivo. When CyA treatment was continued throughout the period during which unresponsiveness to the graft is induced by anti-CD4 mAb therapy, 50 % of the grafted hearts were rejected once the CyA was discontinued. In conclusion, the combined use of anti-CD4 mAb therapy and CyA did not have a negative effect on graft survival in this model when the two agents were used concurrently at the time of transplantation. Received: 2 October 1996 Received after revision: 31 January 1997 Accepted: 5 February 1997  相似文献   
850.
Knife injuries can be classified into stabbing injuries and multiple laceration or multiple chops, the latter being much more common in Chinese communities. It is the mark of criminal gang attacks with their tendency to use long knives and choppers rather than guns. The intention is often to wound rather than kill. A survey of 89 cases revealed that 90% of the victims are men, with a mean age of 27 years; 75% was admitted to the hospital at night, and in 78% of the cases the assailants were persons unknown, or so we were told by the victims. The reasons for the attacks were also not given. Most of the women victims were assaulted by their spouse. Some 74% of the patients suffered three to six lacerations; 62% of the injuries were on the extensor surfaces of the upper limbs, while the hand and the back of the trunk were also common sites. The type of management differs from that for stabbing injuries. There were no fatalities, and less than half of the patients required blood transfusion. The average hospital stay was 6.2 days. The morbidity of these injuries involves damaged tendons and nerves.  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