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   1405059篇
  免费   102480篇
  国内免费   1976篇
耳鼻咽喉   18284篇
儿科学   45563篇
妇产科学   37984篇
基础医学   207915篇
口腔科学   41647篇
临床医学   128324篇
内科学   278772篇
皮肤病学   30801篇
神经病学   113665篇
特种医学   51081篇
外国民族医学   288篇
外科学   195899篇
综合类   27001篇
现状与发展   4篇
一般理论   620篇
预防医学   119777篇
眼科学   30684篇
药学   101207篇
  7篇
中国医学   2633篇
肿瘤学   77359篇
  2021年   12626篇
  2019年   12957篇
  2018年   17674篇
  2017年   13441篇
  2016年   14205篇
  2015年   16493篇
  2014年   22653篇
  2013年   33342篇
  2012年   46702篇
  2011年   49641篇
  2010年   27918篇
  2009年   26598篇
  2008年   45090篇
  2007年   48227篇
  2006年   47209篇
  2005年   46572篇
  2004年   44600篇
  2003年   42352篇
  2002年   39535篇
  2001年   59473篇
  2000年   60484篇
  1999年   51176篇
  1998年   14621篇
  1997年   13224篇
  1996年   13638篇
  1995年   12758篇
  1994年   11923篇
  1992年   40132篇
  1991年   39531篇
  1990年   38140篇
  1989年   36978篇
  1988年   34256篇
  1987年   33489篇
  1986年   31894篇
  1985年   30123篇
  1984年   22914篇
  1983年   19947篇
  1982年   11827篇
  1979年   21665篇
  1978年   15863篇
  1977年   13177篇
  1976年   12176篇
  1975年   13256篇
  1974年   16019篇
  1973年   15789篇
  1972年   14875篇
  1971年   13887篇
  1970年   13168篇
  1969年   12427篇
  1968年   11580篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
71.
72.
The present study demonstrates that alcohol-induced memory impairment can be attenuated by pretreatment with an oral tryptophan supplementation. These results provide support for the role of a brain serotonin deficit in this impairment and highlight the impact a dietary manipulation can have on a complex behavioral process.  相似文献   
73.
74.
The Dundee Memory Clinic was established in 1991. This paper reviews the diagnosis of the first 150 attenders and compares the findings with those of other memory clinics.  相似文献   
75.
This study examines the relationships between patient characteristics and surrogate decision maker characteristics on surrogates' preferences for life-sustaining treatments. Caucasian and African-American caregivers and noncaregivers (n=110) responded to a vignette involving a medical crisis in a hospitalized older man who suffered cardiac arrest, one of the most common causes of death among older Americans. This man was described as either a cognitively intact or moderately demented family member. Participants made decisions regarding cardiopulmonary resuscitation (CPR), CPR and ventilation, and CPR and tube feeding. Analyses followed a 2 (cognitive status) 2 (caregiving status) 2 (racial background) analysis of covariance design, with education and income used as covariates. In general, participants were less likely to initiate life-sustaining treatments in demented patients. Caucasian caregivers were less likely to initiate CPR and ventilation and CPR and tube feeding. Results indicate that characteristics of the patient and the interplay between cultural issues and experience with caregiving affect surrogate judgements regarding life-sustaining treatments.  相似文献   
76.
Choristomas, masses of normal tissues in aberrant locations, contain smooth muscle fibers and fibrous tissues. We describe the MR imaging features of two choristomas located in the internal auditory canals and arising from the facial and vestibulocochlear nerves. Both lesions enhanced with contrast material. In one case, enhancement was seen in the geniculate ganglion and greater superficial petrosal nerve. In the other, a medial component enhanced less than the lateral component did.  相似文献   
77.
The ability of three Porphyromonas spp., seven Prevotella spp., seven Fusobacterium spp. and two related Bacteroides spp. (B. levii and B. macacae) to degrade an extensive range of synthetic endo-, amino- and diamino peptidase substrates linked to the fluorescent leaving group 7-amido-4-methylcoumarin (NHMec) was investigated. Many more species than was previously recognized exhibited peptidase activities, albeit at lower levels than those already described for Porphyromonas gingivalis. Detection of chymotrypsin-like activity was dependent on which of three NHMec-linked substrates was used, but all species exhibited degradative activity with at least one of these substrates. Elastase-like activity was detected in all species though not all species reacted with each of the elastase substrates. Glycylprolyl peptidase activity was detected in all of the species tested with the exception of F. mortiferum, F. gonidiaformans, F. naviforme and F. necrophorum. While the detection of peptidase activities does not appear to be useful for the differentiation of species within the genera Bacteroides and Prevotella, its ability to differentiate species of the genus Porphyromonas or Fosobacterium further investigation.  相似文献   
78.
summary The aetiology of denture stomatitis is not clear from the literature. Some studies show its aetiology as Candida albicans, while other reports point out the significance of microorganisms. In this study the existence of C. albicans and microorganisms was investigated in subjects with and without denture stomatitis. The results showed that a combination of C. albicans and microorganisms is more likely to be responsible for denture stomatitis.  相似文献   
79.
Piecewise constant incidence models were developed to estimate the force of infection in women from age-and time-specific antenatal or neonatal seroprevalence data. Differential inclusion of infected women in sero-surveys compared to uninfected women was taken into account, with respect to both changes in inclusion rate following infection, and changes in relative inclusion rate over calendar time. These models were applied to anonymous HIV seroprevalence data collected from neonates born to black and Hispanic women in New York City 1988-1992, with incidence and fertility parameters estimated by maximum likelihood. Estimates of inclusion rate parameters accorded well with what is known about the natural history of HIV. The data could not distinguish between additive and multiplicative combination of the effects of age and time on incidence. Incidence was strongly dependent on age with the highest incidence in women aged 20-34 years. There was strong evidence that incidence had been falling in Hispanic women since 1982-1984. The results illustrate the extent to which trends in incidence over time may be confounded by changes in the relative inclusion rate of infected and uninfected women.  相似文献   
80.
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