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   25750篇
  免费   6828篇
  国内免费   83篇
耳鼻咽喉   376篇
儿科学   851篇
妇产科学   670篇
基础医学   1613篇
口腔科学   1483篇
临床医学   7233篇
内科学   5605篇
皮肤病学   785篇
神经病学   3163篇
特种医学   679篇
外科学   3057篇
综合类   252篇
现状与发展   2篇
一般理论   21篇
预防医学   3612篇
眼科学   505篇
药学   797篇
中国医学   11篇
肿瘤学   1946篇
  2024年   233篇
  2023年   1419篇
  2022年   521篇
  2021年   1038篇
  2020年   1362篇
  2019年   815篇
  2018年   1832篇
  2017年   1890篇
  2016年   1920篇
  2015年   1948篇
  2014年   2252篇
  2013年   2314篇
  2012年   1360篇
  2011年   1412篇
  2010年   1468篇
  2009年   1724篇
  2008年   993篇
  2007年   885篇
  2006年   891篇
  2005年   760篇
  2004年   653篇
  2003年   538篇
  2002年   551篇
  2001年   331篇
  2000年   183篇
  1999年   296篇
  1998年   348篇
  1997年   335篇
  1996年   352篇
  1995年   297篇
  1994年   202篇
  1993年   192篇
  1992年   151篇
  1991年   123篇
  1990年   96篇
  1989年   111篇
  1988年   79篇
  1987年   73篇
  1986年   76篇
  1985年   86篇
  1984年   75篇
  1983年   55篇
  1982年   59篇
  1981年   39篇
  1980年   33篇
  1979年   22篇
  1978年   25篇
  1977年   24篇
  1975年   17篇
  1972年   17篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
21.
The prevalence of heavy alcohol consumption is a major problem of increasing proportions throughout the world. Although alcohol sensitizing drugs and more recently serotonin uptake inhibitors are drug interventions with some following, their long term beneficial consequences have yet to be demonstrated. In recent years, we have demonstrated that manipulating activity in the renin-angiotensin system will dramatically alter voluntary alcohol consumption in rats. Based on these findings, the present study evaluated the ability of a class of drugs known as the angiotensin converting enzyme inhibitors to reduce voluntary alcohol drinking in laboratory animals. These drugs prevent the conversion of angiotensin I to angiotensin II. They have been licensed for use in Europe and North America and are indicated in the treatment of hypertension. Our experiments showed that both captopril (Capoten, Squibb) and enalapril (Vasotec, Merck Sharpe & Dohme) can reduce alcohol drinking in both normotensive and hypertensive animals regardless of whether the pattern of intake is in a bout or of a less exaggerated nature. Furthermore, this change in alcohol intake can occur without concomitant changes in blood pressure, plasma renin activity, overall fluid balance, or the distribution and metabolism of alcohol. Taken together these findings suggest that the angiotensin converting enzyme inhibitors should be evaluated in a clinical setting for they may prove to be a useful new treatment or treatment adjunct for alcohol abuse in humans.  相似文献   
22.
Objectives Compare the effect of high doses of inhaled corticosteroids on bone loss in subjects with moderate to severe asthma or mild asthma, and examine the influence of dietary intake on bone metabolism. Design A survey on the effects of corticotherapy and nutrition on bone density was conducted in 74 subjects currently being treated for asthma in the asthma clinic of Hospital Laval (Sainte-Foy, Quebec, Canada). Fifty-eight subjects completed the study (attrition RATE=15%).

Main outcome measures In all subjects expiratory volumes were determined and urinary analysis was conducted for hydroxyproline, calcium, phosphorus, and cortisol levels. Osteocalcin, calcium, phosphorus, cortisol, alkaline phosphatase, and γ-glutamyltransferase levels were measured in blood samples. Bone density of the lumbar spine was determined by means of dual-energy x-ray absorptiometry. Nutrition evaluation was based on a 3-day food diary analyzed using progiciel Nutri 91. The nutritional parameters examined were calcium; phosphorus; magnesium; zinc; vitamins A, C, and D; protein; total fiber; oxalates; energy; caffeine; and alcohol in relation to bone density.

Subjects Thirty-one patients with moderate to severe asthma who had been taking more than 1,000 μg beclomethasone per day or the equivalent for more than 2 years and 27 patients with mild asthma who were taking less than 500 μg beclomethasone per day or the equivalent.

Statistical analyses performed Four factor analysis of variance with hierarchized interactions of four levels, Duncan's test, Pearson correlation coefficients.

Results Blood levels of osteocalcin and protein intake were lower in patients with moderate to severe asthma than in those with mild asthma (P<.05). Significant correlations (P<.02) were observed between bone density and calcium intake (r=.40), phosphorus intake (r=.35), protein intake (r=.30), and serum alkaline phosphatase level (r=−.30). Bone density was not significantly different between the two groups of patients with asthma.

Applications A follow-up of patients with asthma who are taking inhaled corticosteroids is needed to assess bone density, osteocalcin levels, and dietary intakes of calcium. Verify if osteocalcin level decreases over time in patients with moderate to severe asthma, monitor possible modifications in bone density, and verify if the correlation between dietary calcium and bone density is maintained. J Am Diet Assoc. 1997;97:1401–1406.  相似文献   

23.
24.
Fetal scalp blood sampling (FSBS), in conjunction with fetal heart rate monitoring, is a method of fetal surveillance that may avoid cesarean delivery of the healthy fetus or indicate the need for immediate delivery of a compromised fetus. Some researchers have recently begun to question the efficacy of FSBS. In this article, three nurse-midwives discuss FSBS as a tool in assessing fetal well-being during labor and consider whether FSBS is a nurse-midwifery procedure.  相似文献   
25.
26.
27.
28.
BACKGROUND: Strain rate (SR) imaging (SRI) is a tissue Doppler-based method of regional myocardial deformation imaging. The aim of this study was to see whether SRI could quantify changes in myocardial mechanical function after an acute myocardial infarction, and to follow the time course of these changes. METHODS: In all, 26 consecutive patients with first-time acute myocardial infarctions were examined on days 1, 7, and 90. Segments were analyzed with SRI and wall-motion score. RESULTS: Peak systolic SR in infarcted segments increased significantly in magnitude from day 1 to 7 (-0.45 to -0.68 s -1 , P < .001), but not after day 7. The deformation rate in border zone segments also increased significantly from day 1 to 7 (-0.8 to -0.95 s -1 , P < .05), with no further significant changes at 3 months. In normal segments, peak systolic SR decreased in magnitude during the first week. Systolic strain showed similar results as peak systolic SR. CONCLUSION: SRI can demonstrate small changes in deformation rate from midinfarct through the infarct and border zone to normal myocardium. It can also show changes over time, probably as a result of recovery of stunned myocardium.  相似文献   
29.
30.
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