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   809篇
  免费   63篇
  国内免费   8篇
儿科学   32篇
妇产科学   25篇
基础医学   110篇
口腔科学   8篇
临床医学   68篇
内科学   256篇
皮肤病学   8篇
神经病学   44篇
特种医学   90篇
外科学   55篇
综合类   10篇
预防医学   82篇
眼科学   6篇
药学   62篇
肿瘤学   24篇
  2022年   3篇
  2021年   5篇
  2020年   4篇
  2019年   7篇
  2018年   16篇
  2017年   5篇
  2016年   12篇
  2015年   11篇
  2014年   10篇
  2013年   30篇
  2012年   25篇
  2011年   27篇
  2010年   36篇
  2009年   22篇
  2008年   33篇
  2007年   38篇
  2006年   35篇
  2005年   41篇
  2004年   29篇
  2003年   19篇
  2002年   30篇
  2001年   20篇
  2000年   19篇
  1999年   23篇
  1998年   33篇
  1997年   33篇
  1996年   37篇
  1995年   27篇
  1994年   31篇
  1993年   20篇
  1992年   19篇
  1991年   8篇
  1990年   21篇
  1989年   22篇
  1988年   13篇
  1987年   17篇
  1986年   14篇
  1985年   14篇
  1984年   7篇
  1983年   4篇
  1982年   4篇
  1981年   10篇
  1980年   7篇
  1979年   5篇
  1978年   3篇
  1977年   4篇
  1976年   10篇
  1975年   4篇
  1970年   2篇
  1967年   2篇
排序方式: 共有880条查询结果,搜索用时 14 毫秒
51.
52.
Roxatidine acetate, a new H2 receptor antagonist, was compared with ranitidine in the treatment of duodenal ulcers in a double-blind multicentre study. Eighty-four patients with endoscopically proven duodenal ulcer were randomized to receive 150 mg roxatidine acetate or 300 mg ranitidine at bedtime. Repeat endoscopy was performed after 4 weeks (25–33 days) and if the ulcer had not healed, another endoscopy was performed after a further 4 weeks of treatment. Using per protocol analysis 73.6% of ulcers treated with roxatidine healed at 4 weeks compared to 72.2% of ulcers treated with ranitidine (P=NS). The healing rates at 8 weeks were 92% with roxatidine and 83.3% with ranitidine (P=NS). Using equivalence tests, the healing rate of roxatidine was found to be equivalent to that of ranitidine within a 20% region. Roxatidine users took significantly less antacids than ranitidine users (P < 0.05). There were no significant adverse effects due to roxatidine or ranitidine. Roxatidine is a safe effective drug in the treatment of duodenal ulcers with a healing rate comparable to that of ranitidine.  相似文献   
53.
Newlin  N; Silver  TM; Stuck  KJ; Sandler  MA 《Radiology》1981,139(1):155-159
Ultrasonic features of 21 surgically confirmed pyogenic liver abscesses in 18 patients were analyzed. Typical lesions were round or ovoid with a discrete, irregular, echo-poor margin. The number and intensity of internal echoes and sound transmission were variable. Such lesions can be aspirated percutaneously for definitive preoperative diagnosis. Pyogenic liver abscesses appear to have more ragged walls and are less frequently elliptical or multilocular than abscesses elsewhere in the abdomen.  相似文献   
54.
Ultrasound diagnosis of hydrocolpos and hydrometrocolpos   总被引:1,自引:0,他引:1  
Wilson  DA; Stacy  TM; Smith  EI 《Radiology》1978,128(2):451
  相似文献   
55.
56.

Background  

Improved survival due to advances in neonatal care has brought issues such as postnatal growth and development more to the focus of our attention. Most studies report stunting in children born very preterm and/or small for gestational age. In this article we study the growth pattern of these children and aim to identify factors associated with postnatal catch-up growth.  相似文献   
57.
OBJECTIVE: To describe and compare women and health care professionals' preferences for Down's Syndrome screening tests with different test characteristics. DESIGN: Cross sectional questionnaire based conjoint analysis study. SETTING: London teaching hospital. SAMPLE: 291/383 women in their first or second trimester of pregnancy and 98/122 health care professionals (41 obstetricians, senior house officers and above and 57 qualified midwives) providing care at the same hospital. METHODS: Women completed a questionnaire while attending a clinic visit for a dating scan or a routine 20-week anomaly scan. Health care professionals completed a postal questionnaire. MAIN OUTCOME MEASURES: The relative values participants attach to Down's Syndrome screening test attributes: time of test, detection rate and risk of miscarriage of a baby unaffected by Down's Syndrome as a result of subsequent diagnostic tests. RESULTS: Pregnant women and health care professionals shared broadly similar relative values regarding the importance of safe tests, conducted early and with high detection rates. When asked to choose between different Down's Syndrome screening tests, health care professionals valued earlier tests more highly than did women. CONCLUSIONS: While pregnant women and health care professionals share similar relative values regarding optimal prenatal tests, health care professionals place a higher value on earlier tests. This may result in screening policies that overweight timing in the selection of a test to the relative neglect of tests associated with lower miscarriage rates and higher detection rates but conducted later in pregnancy.  相似文献   
58.
59.
We review the present knowledge on the biological mechanisms of action of probiotics and prebiotics. They include direct effects in the intestinal lumen or on intestinal or immune cells, and indirect mechanisms through modulation of the endogenous microflora (composition or functions such as butyrate production) or of the immune system.  相似文献   
60.
A proportion of those receiving negative results following predictive genetic testing desire future bowel screening. This is despite a negative result meaning a general population risk of 1:7500 and despite bowel screening being experienced as aversive and clinically unnecessary. This study aimed to investigate perceptions of risk, illness, and tests amongst those receiving negative results following predictive genetic testing. Interviews with nine people receiving negative genetic test results for familial adenomatous polyposis (FAP) were analyzed using the qualitative method, interpretative phenomenological analysis (IPA). Those not reassured by negative genetic test results perceived a continuing risk to themselves and to their children. Two sets of perceptions emerged that might explain this: (1). perceptions of the genetic basis of the condition (FAP). Although the condition was perceived to be genetic, genetic status was seen as transient, so a result today could not predict the future. The condition was also seen as caused by factors other than genes, so information about only one risk factor could not be reassuring. (2). Perceptions of the genetic test. There was a lack of conviction in the ability of the genetic test, based on a blood sample, to predict a disease located in the bowel. These results suggest that some individuals receiving negative test results are not reassured because of their representations of the cause of their condition and the nature of the tests they undergo. It may be that eliciting and, when appropriate, changing people's representations prior to testing may enable those receiving negative results to be more reassured about their residual risk.  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