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   18984篇
  免费   1774篇
  国内免费   89篇
耳鼻咽喉   144篇
儿科学   549篇
妇产科学   332篇
基础医学   2797篇
口腔科学   390篇
临床医学   2274篇
内科学   4033篇
皮肤病学   480篇
神经病学   1453篇
特种医学   768篇
外科学   3081篇
综合类   424篇
一般理论   10篇
预防医学   1605篇
眼科学   256篇
药学   1279篇
中国医学   12篇
肿瘤学   960篇
  2021年   228篇
  2020年   176篇
  2019年   264篇
  2018年   260篇
  2017年   236篇
  2016年   256篇
  2015年   280篇
  2014年   390篇
  2013年   573篇
  2012年   883篇
  2011年   820篇
  2010年   463篇
  2009年   496篇
  2008年   756篇
  2007年   853篇
  2006年   811篇
  2005年   817篇
  2004年   752篇
  2003年   723篇
  2002年   671篇
  2001年   571篇
  2000年   677篇
  1999年   547篇
  1998年   298篇
  1997年   286篇
  1996年   296篇
  1995年   223篇
  1994年   216篇
  1993年   217篇
  1992年   501篇
  1991年   477篇
  1990年   422篇
  1989年   434篇
  1988年   425篇
  1987年   399篇
  1986年   400篇
  1985年   364篇
  1984年   326篇
  1983年   237篇
  1982年   154篇
  1981年   151篇
  1980年   142篇
  1979年   268篇
  1978年   172篇
  1977年   135篇
  1976年   149篇
  1975年   129篇
  1974年   168篇
  1973年   165篇
  1972年   157篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
11.
12.
Physicians have long been wary of chronically administering neuroleptic drugs to the demented elderly for fear of significant side effects. In this article, the authors present evidence to support these fears. A discussion of the early and late emerging side effects of neuroleptic drugs is presented.  相似文献   
13.
14.
The effects of labeling a person as hypertensive have important implications for hypertension screening. The Hypertension Detection and Follow-up Program (HDFP) provides an opportunity to examine the effects of labeling, treatment, and study assignment on a large group of hypertensives (n = 10,070). Their answers to questions regarding perceived health and general well-being asked at baseline and again one year later were analyzed. There was no significant change in the perceived health status of persons who were unaware of their hypertension at baseline and remained untreated at one year (labeling alone). The effect of labeling plus treatment was associated with a significant decrease in perceived health. The effect of antihypertensive drug therapy on perceived health status was examined in persons who were aware of their hypertension but not on treatment at baseline, and on treatment at one year. The stepped care group (SC) had a significant improvement in their perceived health and a significant decrease in the amount of time spent worrying about their health. The referred care group (RC) had no change. Program assignment effects were studied in individuals aware of their hypertension and on treatment both at baseline and one year later. Both the SC and RC groups had a significant improvement in their perceptions of their health status. The SC group had a significant decrease in time spent worrying about their health, while the RC group showed no change. These reassuring results fail to support the suggestion that labeling persons as hypertensive is necessarily followed by negative psychological consequences.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   
15.
Osteoporosis is a common disease with a strong genetic component characterized by reduced bone mass and an increased risk of fragility fractures. Bone mineral density (BMD) is the most important determinant of osteoporotic fracture risk, but the genes responsible for BMD regulation and fracture are incompletely defined. To enable multi-center studies to examine the genetic influences on BMD there is a requirement to standardize measurements across different manufacturers of bone densitometers, different versions of machines and different normative ranges. This paper describes a method developed to allow near-identical subjects with low age-adjusted BMD (based on Z-scores) to be recruited in 17 centers using 27 different densitometers. Cross-calibration was based on measurements using a European spine phantom circulated to all centers and measured ten times on each individual machine. From theses values an individual exponential curve, based on nominal versus observed BMD, was derived for each machine. As expected, there were large and significant variations in nominal BMD values, not only between scanners from different manufacturers but also between different versions of scanners from the same manufacturer. Hologic scanners tended to underestimate the nominal BMD, while Lunar scanners overestimated the value. Norland scanners gave mixed values over estimating BMD at the lower nominal value (0.5 g/cm2) while underestimating the value at the higher value (1.5 g/cm2). The validity of the exponential equations was tested using hip and spine measurements on 991 non-proband women from a familial osteoporosis study (FAMOS). After cross-calibration there was a considerable reduction in variation between machines. This observation, coupled with the absence of a similar reduction in variation attributable to a linear regression on age, demonstrated the validity of the cross-calibration approach. Use of the cross-calibration curves along with a standard normative range (in the case of this study, the Hologic normative range) allowed age-specific Z-scores to be used as an inclusion criterion in this genetic study, a method that will be useful for other trials where age-specific BMD inclusion criteria are required.  相似文献   
16.
The mechanism of release from sustained-release adinazolam mesylate tablets was assessed by the Higuchi equation and by analysis of drug release profiles through 60% released using the Peppas equation. Computed values of the diffusional exponent, n, ranged from 0.59 to 0.66. Values of n in this range are consistent with a mixed mechanism of release, with diffusion of drug through the hydrated polymer matrix and relaxation of this matrix being the principal processes controlling release. The rate of in vitro drug release was increased for half tablets relative to whole tablets and is attributed to an increase in the surface to volume ratio of half tablets of about 16%. This increase in surface-to-volume ratio of half tablets was reflected by an increase in the constant, k, from the Peppas equation of 20–23% and by an increase in the slope of Higuchi plots of 12–18% for four lots of tablets. In vivo/in vitro relationships from two bioavailability studies were thoroughly evaluated. Using either a linear or a quadratic relationship, an in vivo/in vitro correlation exists for sustained-release adinazolam mesylate tablets.  相似文献   
17.
18.
19.
20.
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