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   1173篇
  免费   109篇
  国内免费   3篇
耳鼻咽喉   4篇
儿科学   29篇
妇产科学   48篇
基础医学   139篇
口腔科学   4篇
临床医学   137篇
内科学   219篇
皮肤病学   23篇
神经病学   181篇
特种医学   32篇
外科学   142篇
综合类   10篇
一般理论   1篇
预防医学   150篇
眼科学   11篇
药学   80篇
肿瘤学   75篇
  2023年   15篇
  2022年   19篇
  2021年   57篇
  2020年   31篇
  2019年   45篇
  2018年   49篇
  2017年   32篇
  2016年   42篇
  2015年   44篇
  2014年   53篇
  2013年   62篇
  2012年   107篇
  2011年   109篇
  2010年   51篇
  2009年   40篇
  2008年   56篇
  2007年   74篇
  2006年   61篇
  2005年   51篇
  2004年   48篇
  2003年   31篇
  2002年   35篇
  2001年   7篇
  2000年   9篇
  1999年   16篇
  1998年   8篇
  1997年   8篇
  1996年   3篇
  1995年   4篇
  1994年   5篇
  1991年   8篇
  1990年   8篇
  1989年   9篇
  1988年   3篇
  1987年   5篇
  1986年   5篇
  1985年   3篇
  1984年   8篇
  1983年   3篇
  1980年   3篇
  1979年   6篇
  1978年   7篇
  1977年   5篇
  1975年   3篇
  1973年   3篇
  1971年   3篇
  1967年   5篇
  1966年   6篇
  1965年   2篇
  1963年   2篇
排序方式: 共有1285条查询结果,搜索用时 31 毫秒
1.
2.
Background: It is widely known that a proportion of university students use drugs. However, much less is known about how they source and supply their drugs. Objectives: In this article, we investigate student drug trading activity, including how they obtained their drugs, whether they sold drugs, and the extent to which their drug trading might be described as a form of “social supply”. Methods: A survey was conducted of all students across seven of the nine universities of Wales. In total, 7855 students submitted a questionnaire and 1877 of these reported drug use in the current academic year. All students who reported using one or more illegal drugs in the current academic year were asked how they obtained their drugs, how they funded their drug use, whether they had sold, traded or given away illegal drugs, along with their motives for drug trading. Results: The results showed that about half of users obtained drugs solely from friends and associates and one-fifth obtained them solely from external dealers. One-quarter used friends and associates as well as external markets. In many cases, supplying drugs amounted to sharing them or giving them away. However, over one-third of students said that they had sold drugs. Conclusions: Overall, the methods of sourcing and supplying drug among university students shares features of both “social supply” and “traditional” drug markets. We conclude that the student drug market investigated is best described as a “hybrid” combination of both.  相似文献   
3.
4.
5.
Two cases of photosensitivity to the nonsteroidal anti-inflammatory agent piroxicam are described. The action spectrum appears to be in the ultraviolet A (UVA) range (320 to 400 nm). Hallmarks of the photosensitivity reaction include an acute eczematous dermatitis with frank vesicle formation clinically and spongiosis and a perivascular mononuclear cell infiltrate histologically. Piroxicam and other nonsteroidal anti-inflammatory drugs are capable of inducing cutaneous photosensitivity.  相似文献   
6.
We are interested in the mechanisms that generate the mature cerebral cortex. We used bromodeoxyuridine (BrdU) to label cortical cells as they were being born. We followed the fates of specific sets of cortical precursors in normal mice and in mice in which other groups of cortical progenitors had been destroyed with the antimitotic agent methylazoxymethanol acetate (MAM Ac). In normal mice, most cells destined for the cerebral cortex were produced from embryonic day 12 (E12) to E16 in the expected inside-to-outside sequence (deep layers first, superficial layers last). Injection of MAM Ac at E13 killed cells that would normally have contributed to the deep cortical layers. As a consequence, the cortex was thinned by ∼25% at postnatal day 21 (P21). However, all laminae were present and had normal connections with subcortical structures, although all were proportionately thinner. BrdU injected on E16 labelled a normally sized complement of cells that spanned a larger proportion of the depth of the thinned cortex. Thus, the deep cortical layers comprised many cells that were born several days later than normal. At embryonic ages prior to E12, a transient set of cells is produced in the early telencephalon. After injection with MAM Ac at E10, the cortex appeared histologically and histochemically normal at P21. However, many cells that would normally have contributed to superficial cortex (born on E15) were significantly deeper than normal. These results suggest that, during the early stages of cortical development, the nervous system is sufficiently plastic to compensate to some extent for the destruction of specific precursor cells by altering the fates of neurons born later. They indicate that the embryonic date on which a cortical cell is born does not necessarily determine its eventual phenotype.  相似文献   
7.
OBJECTIVES: The introduction of 48-hour wireless pH testing offers clinicians a new alternative for the objective documentation of reflux. The success of transnasal wireless pH capsule placement has not been previously described. The purpose of this investigation was to describe our experience with transnasal wireless pH capsule placement. METHODOLOGY: All patients undergoing unsedated transnasal esophagoscopy and wireless pH capsule placement between January 1, 2003 and July 31, 2003 were prospectively evaluated. Data concerning patient tolerance, success of capsule placement and function, complications, and pH recordings were collected. RESULTS: During this time, 46 persons were evaluated. The mean age of the cohort was 52 years. Of the patients, 50% were male. The indications for the procedure were chronic cough (18/46), gastroesophageal reflux disease (18/46), and larygopharyngeal reflux (10). Of the procedures performed, 85% (39/46) were successful. Complications included epistaxis (2/46), laryngospasm (2/46), and vasovagal reaction (1/46). CONCLUSIONS: The transnasal placement of a wireless pH capsule is a safe and effective diagnostic adjunct to unsedated transnasal esophagoscopy.  相似文献   
8.
Although anxiety is a well-established obstacle to the delivery of effective health care, there have been no attempts to measure it in the optometric consulting room. In this paper, we introduce physiological and psychological techniques that may be used to evaluate anxiety and arousal in the consulting room and present data from a small group of patients attending for a routine eye examination. Specifically, arousal was assessed before, during, and after the examination by measuring skin conductance in five patients. Anxiety was evaluated using the State-Trait Anxiety Inventory. Our data confirm the ability of these techniques to quantify arousal and anxiety in the optometric consulting room and reveal a previously unknown but important facet of the eye examination. We conclude that these techniques are suitable for use in further experimental work and may be used to identify factors capable of reducing anxiety in the optometric consulting room.  相似文献   
9.
10.
OBJECTIVE: Breast-feeding is associated with better child development outcomes, but uncertainty remains primarily due to the close relationship between breast-feeding and socioeconomic status. This study assesses the issue in a low socioeconomic status sample where breast-feeding was close to universal. METHODS: Seven hundred eighty-four Chilean children were followed longitudinally from infancy. All but four were initially breastfed, 40% nursed beyond 12 months, and infant growth was normal. Child development was assessed at 5(1/2) years by a cognitive, language, and motor test battery. The duration of breast-feeding as the sole milk source was analyzed as a continuous variable, adjusting for a comprehensive set of background factors. RESULTS: The relationship between breast-feeding and most 5(1/2)-year developmental outcomes was nonlinear, with poorer outcome for periods of breast-feeding as the sole milk source for <2 months or >8 months--statistically significant for language, motor, and one comprehensive cognitive test, with a suggestive trend for IQ. CONCLUSIONS: The observed nonlinear relationships showed that breast-feeding as the sole milk source for <2 months or >8 months, compared with 2-8 months, was associated with poorer development in this sample. The latter finding requires replication in other samples where long breast-feeding is common and socioeconomic status is relatively homogeneous.  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