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   5623篇
  免费   542篇
  国内免费   3篇
耳鼻咽喉   124篇
儿科学   205篇
妇产科学   227篇
基础医学   833篇
口腔科学   109篇
临床医学   623篇
内科学   1225篇
皮肤病学   59篇
神经病学   420篇
特种医学   153篇
外科学   713篇
综合类   166篇
一般理论   1篇
预防医学   552篇
眼科学   39篇
药学   346篇
中国医学   5篇
肿瘤学   368篇
  2022年   42篇
  2021年   68篇
  2020年   44篇
  2019年   96篇
  2018年   118篇
  2017年   88篇
  2016年   96篇
  2015年   103篇
  2014年   132篇
  2013年   223篇
  2012年   277篇
  2011年   277篇
  2010年   177篇
  2009年   138篇
  2008年   262篇
  2007年   258篇
  2006年   265篇
  2005年   258篇
  2004年   236篇
  2003年   239篇
  2002年   235篇
  2001年   178篇
  2000年   182篇
  1999年   152篇
  1998年   72篇
  1997年   60篇
  1996年   54篇
  1995年   53篇
  1994年   59篇
  1993年   45篇
  1992年   126篇
  1991年   126篇
  1990年   107篇
  1989年   101篇
  1988年   109篇
  1987年   99篇
  1986年   107篇
  1985年   87篇
  1984年   56篇
  1983年   58篇
  1982年   36篇
  1980年   36篇
  1979年   77篇
  1978年   51篇
  1976年   42篇
  1974年   42篇
  1973年   32篇
  1972年   28篇
  1970年   29篇
  1969年   30篇
排序方式: 共有6168条查询结果,搜索用时 15 毫秒
31.
A theoretical model of prevention addressing adolescents at-risk of offending was developed then utilised to assess a primary and secondary prevention program. The study of the wilderness-based practise was conducted between September 1992 and October 1994, adopting a pre-post-follow-up quasi-experimental design using waiting periods to establish treatment and control groups. Maturational changes were gauged over a 12 month period of 44 male and 18 female voluntary Australian adolescents between the ages of 15 and 25 years. Significant differences between the treatment and control groups in the psychometric areas of general self-esteem and self-actualisation were found establishing positive program effect on participants. Further, the long term effect of this program in preventing participants initial contact with court proceedings or reducing further involvement respectively, over a twelve month period was substantiated. It was shown that following this experience post program goals of employment and education for adolescents at-risk were positively influenced.  相似文献   
32.
OBJECTIVE AND DESIGN: Neutrophil-derived hypochlorous acid (PMN-HOCL) is a potent bactericidal and fungicidal agent. Neutrophils from patients with multiple organ failure (MOF) have an altered ability to inhibit Candida albicans. Conversely antifungal agents are effective in decreasing mortality in MOF patients with fungaemia. We determined the effect on the rate of production of PMN-HOCL in a series of MOF patients with C. albicans fungaemia when antifungal agents are administered. SUBJECTS AND METHODS: Eleven patients with MOF were recruited. Four patients had culture-positive C. albicans fungaemia (group 1) and 7 patients with MOF but without C. albicans fungaemia acted as controls (group 2). HOCL assays were performed on peripheral blood PMN obtained from group 1 and group 2 patients. RESULTS: The maximum PMN-HOCL production rate for group 1 increased from 0.24 nmol/million PMN/min to 0.8 nmol/million PMN/min after treatment with antifungal agents (p < 0.01) (Mann-Whitney U test) whereas the PMN-HOCL kinetic (rate) curves for group 1 post-treatment and for group 2 were similar (student's-t-test). CONCLUSIONS: These findings suggest that antifungal treatment improve PMN-HOCL production in MOF patients with C. albicans fungaemia and may improve the effectiveness in eradicating the organism.  相似文献   
33.
Both HIV infection and methamphetamine dependence can be associated with brain dysfunction. Little is known, however, about the cognitive effects of concurrent HIV infection and methamphetamine dependence. The present study included 200 participants in 4 groups: HIV infected/methamphetamine dependent (HIV+/METH+), HIV negative/methamphetamine dependent (HIV-/METH+), HIV infected/methamphetamine nondependent (HIV+/METH-), and HIV negative/methamphetamine nondependent (HIV-/METH-). Study groups were comparable for age, education, and ethnicity, although the HIV-/METH- group had significantly more females. A comprehensive, demographically corrected neuropsychological battery was administered yielding a global performance score and scores for seven neurobehavioral domains. Rates of neuropsychological impairment were determined by cutoff scores derived from performances of a separate control group and validated with larger samples of HIV+ and HIV- participants from an independent cohort. Rates of global neuropsychological impairment were higher in the HIV+/METH+ (58%), HIV-/METH+ (40%) and HIV+/METH- (38%) groups compared to the HIV-/METH- (18%) group. Nonparametric analyses revealed a significant monotonic trend for global cognitive status across groups, with least impairment in the control group and highest prevalence of impairment in the group with concurrent HIV infection and methamphetamine dependence. The results indicate that HIV infection and methamphetamine dependence are each associated with neuropsychological deficits, and suggest that these factors in combination are associated with additive deleterious cognitive effects. This additivity may reflect common pathways to neural injury involving both cytotoxic and apoptotic mechanisms.  相似文献   
34.
Social learning theory-based models have recently provided the foundation for a series of twelve controlled human immunodeficiency virus (HIV) risk reduction intervention studies that have examined sexual behavior change. These interventions have been tested with adolescents, gay and bisexual men, inner-city women, college students, and seriously mentally ill adults. We report the first meta-analysis of these intervention studies. We found that, as expected, the mean weighted effect of HIV-risk reduction interventions on behavioral outcomes was positive and strongly significant (d+=0.25). Moreover, the studies’ effect sizes were consistently positive, ranging from 0.11 to 0.53, and were largest when the outcomes were measured close in time to the intervention. We discuss other methodological challenges that, if solved, should enhance the success of future HIV-risk reduction interventions.  相似文献   
35.
1. Subepidermal injection of histamine solutions in isotonic saline in four subjects evoked whealing after a mean delay of 2.6 min, this estimate being derived by regression modelling. 2. Wheal growth was better modelled by the logarithm of time than by time, suggesting that wheal size depends upon assisted diffusion of histamine in the dermis. 3. Wheal growth was piecemeal, not continuous, consistent with the successive involvement of neighbouring vascular territories. 4. Wheal growth was completed by 9 min after injection.  相似文献   
36.
The projections of the superficial layers of the superior colliculus to the pulvinar nucleus in Tupaia were reexamined by injecting WGA-HRP into the tectum. The main result was finding two different patterns of terminations in the pulvinar nucleus: a zone remote from the lateral geniculate nucleus, which occupies the dorsomedial and caudal poles of the pulvinar nucleus, was almost entirely filled with terminals in every case irrespective of the location of the injection site; and a second division of the pulvinar nucleus, adjacent to the lateral geniculate nucleus, contained irregular patches--much more densely populated--and the distribution of patches varied from case to case. We call the first projection "diffuse" and the patchy projection "specific." Next we injected several divisions of the extrastriate visual cortex to find the cortical target of each pathway. The diffuse path terminates in the ventral temporal area (Tv). The specific path terminates in the dorsal temporal area (Td) and area 18. We speculated about the significance of the two pathways: the specific path may be responsible for the preservation of vision after removal of the striate cortex; the diffuse path may have an important place in the evolution of the visual areas of the temporal and occipital lobe. We argued that the target of the diffuse path is in a position to relate limbic and visual impulses and relay the product of such integration to the other visual areas, striate as well as extrastriate cortex.  相似文献   
37.
38.
39.
Cystic fibrosis: prenatal diagnosis and carrier detection by DNA analysis   总被引:5,自引:0,他引:5  
The analysis of restriction fragment length polymorphism (RFLP)s was used to detect 11 polymorphisms that are linked to cystic fibrosis in 42 Australian families with at least one child with cystic fibrosis. The data from all the families were fully informative in regard to the gene for cystic fibrosis (CF). Prenatal assessment was performed for 24 of these families: seven fetuses were assessed to be homozygous for cystic fibrosis, 13 fetuses were heterozygous and three fetuses were free of the CF gene. Of the seven pregnancies in which it was predicted that the infant would be affected by cystic fibrosis, two were continued electively; both have come to term and the infants each were shown to have cystic fibrosis at birth. Of the 17 pregnancies in which it was predicted that the infant would not be affected by cystic fibrosis, 13 have come to term and all the infants but one (who has not yet been followed-up) have been shown to be unaffected by cystic fibrosis at birth. The polymerase chain reaction has been used to amplify the CS.7 and KM.19 loci close to the CF gene. This procedure allows a polymorphic site in each locus to be analysed in a much shorter time (one or two days rather than 10 days) and allows the use of very small test-samples, such as dried blood on filter paper ("Guthrie blood spots"). Our observations confirm the results of overseas studies and indicate that these techniques are eminently useful for prenatal diagnosis and the detection of carriers in the vast majority of Australian families with cystic fibrosis.  相似文献   
40.
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