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   1132篇
  免费   64篇
  国内免费   16篇
耳鼻咽喉   5篇
儿科学   45篇
妇产科学   16篇
基础医学   101篇
口腔科学   21篇
临床医学   157篇
内科学   255篇
皮肤病学   6篇
神经病学   74篇
特种医学   238篇
外科学   98篇
综合类   50篇
预防医学   56篇
眼科学   5篇
药学   40篇
中国医学   7篇
肿瘤学   38篇
  2023年   3篇
  2022年   3篇
  2021年   15篇
  2020年   7篇
  2019年   3篇
  2018年   13篇
  2017年   11篇
  2016年   18篇
  2015年   14篇
  2014年   13篇
  2013年   29篇
  2012年   18篇
  2011年   40篇
  2010年   32篇
  2009年   41篇
  2008年   35篇
  2007年   44篇
  2006年   49篇
  2005年   44篇
  2004年   38篇
  2003年   48篇
  2002年   37篇
  2001年   27篇
  2000年   18篇
  1999年   30篇
  1998年   49篇
  1997年   52篇
  1996年   40篇
  1995年   29篇
  1994年   45篇
  1993年   26篇
  1992年   13篇
  1991年   17篇
  1990年   14篇
  1989年   34篇
  1988年   24篇
  1987年   24篇
  1986年   28篇
  1985年   18篇
  1984年   18篇
  1983年   19篇
  1982年   14篇
  1981年   27篇
  1980年   7篇
  1979年   8篇
  1978年   13篇
  1977年   15篇
  1976年   12篇
  1975年   15篇
  1974年   5篇
排序方式: 共有1212条查询结果,搜索用时 15 毫秒
71.
First rotavirus vaccine licensed: Is there really a need?   总被引:6,自引:0,他引:6  
The first rotavirus vaccine was licensed in the United States on 31 August 1998 for the prevention of severe rotavius diarrhea in children. Despite this landmark in new vaccines, many pediatricians and public health professionals in Europe are uncertain of the need for this vaccine for the routine immunization of infants. In Europe, ample evidence suggests that rotavirus is the most common cause of hospitalizations for severe diarrhea among children, but proper studies documenting the disease burden of rotavirus or th cost-effectiveness of a rotavirus immunization program have only been conducted in the United Kingdom following epidemiologic models used in the United States. All children are infected with rotavirus during their first few years of life, 30-50% of diarrheal hospitalizations among children <5 years are due to this agent, and, by the age of 5 years, between 1 in 40 and 1 in 77 children in Europe and the United States may be hospitalized for rotavirus. The first vaccine is a live, oral preparation combining four different serotypes of rotavirus and administered in three doses with other childhood immunizations. The good efficacy against severe rotavirus diarrhea, the low risk of adverse side effects and the positive costeffectiveness equation have led the two major immunization advisory groups in the U.S. to recommend this vaccine for routine use in American infants. European physicians and policymakers should re-examine the epidemiology and disease burden of rotavirus diarrhea now that an effective method of prevention is at hand. □ Childhood immunization, diseases, rotavirus, vaccination .  相似文献   
72.
A 6‐week‐old infant presenting with near‐drowning was medically paralysed and ventilated on admission. Status epilepticus was found on cerebral function monitoring, without which the diagnosis would have been missed or delayed for many hours. This case illustrates the value of cerebral function monitoring for patients in intensive care, where clinical signs of seizure activity are frequently masked by paralysis and sedation. Conclusion: Limited availability of electroencephalogram (EEG) and cerebral function monitoring (CFM) in paediatric intensive care may inadvertently delay diagnosis and appropriate treatments and so adversely affect outcomes. We propose that round‐the‐clock cerebral function and/or EEG monitoring should be available in all centres that provide paediatric intensive care.  相似文献   
73.
Aims Players can wager on multiple lines of modern slot machines. When they spin and fail to gain any credits, the machine goes into a state of relative quiet. By contrast, when they spin and win, these spins are accompanied by reinforcing sights and sounds. Such reinforcement also occurs when the amount won is less than the spin wager. We sought to show that these ‘losses disguised as wins’, or LDWs, would be as arousing as wins, and more arousing than regular losses. Measurement and participants We measured skin conductance response (SCR) amplitudes and heart‐rate changes following wins, LDWs and losses for 40 novices playing a multi‐line slot machine. Findings SCR amplitudes were similar for wins and LDWs—both were significantly larger than for regular losses. Conclusions For novice players, the reinforcing sights and sounds of the slot machine triggered arousal on wins, where the number of credits gained was greater than the spin wager, but also on ‘losses disguised as wins’ where the amount ‘won’ was less than the spin wager. Despite the fact that players lost money on these spins, these outcomes were more arousing than regular losses where no credits were gained. Although these findings involve novice players, the heightened arousal associated with these losses may have implications for the development of problem gambling, as arousal has been viewed as a key reinforcer in gambling behaviour.  相似文献   
74.
Many drugs have been associated with QTc prolongation and, in some cases, this is augmented by concomitant administration with metabolic inhibitors. The effects of 6 antipsychotics on the QTc interval at and around the time of estimated peak plasma/serum concentrations in the absence and presence of metabolic inhibition were characterized in a prospective, randomized study in which patients with psychotic disorders reached steady-state on either haloperidol 15 mg/d (n = 27), thioridazine 300 mg/d (n = 30), ziprasidone 160 mg/d (n = 31), quetiapine 750 mg/d (n = 27), olanzapine 20 mg/d (n = 24), or risperidone 6-8 mg/d increased to 16 mg/d (n = 25/20). Electrocardiograms (ECGs) were done at estimated Cmax at steady-state on both antipsychotic monotherapy and after concomitant administration of appropriate cytochrome P-450 (CYP450) inhibitor(s). Mean QTc intervals did not exceed 500 milliseconds in any patient taking any of the antipsychotics studied, in the absence or presence of metabolic inhibition. The mean QTc interval change was greatest in the thioridazine group, both in the presence and absence of metabolic inhibition. The presence of metabolic inhibition did not significantly augment QTc prolongation associated with any agent. Each of the antipsychotics studied was associated with measurable QTc prolongation at steady-state peak plasma concentrations, which was not augmented by metabolic inhibition. The theoretical risk of cardiotoxicity associated with QTc prolongation should be balanced against the substantial clinical benefits associated with atypical antipsychotics and the likelihood of other toxicities.  相似文献   
75.
Chemical-DNA adducts provide an integrated measure of exposure, absorption, bioactivation, detoxification, and DNA repair following exposure to a genotoxic agent. Benzo[a]pyrene (BaP), a prototypical polycyclic aromatic hydrocarbon (PAH), can be bioactivated by cytochrome P-450s (CYPs) and epoxide hydrolase to genotoxic metabolites which form covalent adducts with DNA. In this study, we utilized precision-cut rat liver and lung slices exposed to BaP to investigate tissue-specific differences in chemical absorption and formation of DNA adducts. To investigate the contribution of bioactivating CYPs (such as CYP1A1 and CYP1B1) on the formation of BaP-DNA adducts, animals were also pretreated in vivo with 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD, dioxin) prior to in vitro incubation of tissue slices with BaP. Furthermore, the tissue distribution of BaP and BaP-DNA adduct levels from in vivo studies were compared with those from the in vitro tissue slice experiments. The results indicate a time- and concentration-dependent increase in tissue-associated BaP following exposure of rat liver and lung tissue slices to BaP in vitro, with generally higher levels of BaP retained in lung tissue. Furthermore, rat liver and lung slices metabolized BaP to reactive intermediates that formed covalent adducts with DNA. Total BaP-DNA adducts increased with concentration and incubation time. Adduct levels (fmol adduct/microg DNA) in lung slices were greater than liver at all doses. Liver slices contained one major and two minor adducts, while lung slices contained two major and 3 minor adducts. The tissue-specific qualitative profile of these adducts in tissue slices was similar to that observed from in vivo studies, further validating the use of this model. Pretreatment of animals with TCDD prior to in vitro incubation with BaP potentiated the levels of DNA adduct formation. TCDD pretreatment altered the adduct distribution in lung but not in liver slices. Together, the results suggest that tissue-specific qualitative and quantitative differences in BaP-DNA adducts could contribute to the lung being a target tissue for BaP carcinogenesis. Furthermore, the results validate the use of precision-cut tissue slices incubated in dynamic organ culture as a useful model for the study of chemical-DNA adduct formation.  相似文献   
76.
Eating disorders and obesity (EDO) are increasing among youth, having serious long-term physical and psychological consequences. The purpose of this study was to determine if significant differences exist in EDO risk factors following participation of 4–6th grade students in a school-based EDO prevention curriculum. This community-based research project assessed students at baseline and one week following EDO intervention. Primary outcome variables measured self-esteem, body dissatisfaction, and high risk eating attitudes and behaviors. Pre and post-test differences were calculated using mixed models, correcting for clustering within schools and teachers. This study found mean changes in all scores in healthy directions, as well as movement of students into lower risk groups post-intervention. This program demonstrated that a classroom curriculum is associated with decreased risks of EDO in boys and girls, supporting prevention programs at an early age for both sexes. Studies to determine long term benefit and guide booster interventions are warranted.  相似文献   
77.
78.
ReSllm6 Objectif Nos studes Precedentes out montrd une panne fonCtion de la greffe pulmonaire traitde Prdalablementper perfusion forcde retrograde et un stockage d froid inns ~. L' etude Prdsente a pour but de determiner l' effet de ~ surlefiot mngUin du poumon trait4 Prdalablement per perfusion retrograde forcde et un stockage d froid. met~. 12poumons donneurs canins out ate trait4s per perfusion r4tFograde de solution UW. Chez 6 animaux du grouch A, 250ng furent injectes dans l' artrdre…  相似文献   
79.

Background  

Protease inhibitors are known to alter the lipid profiles in subjects treated for HIV/AIDS. However, the magnitude of this effect on plasma lipoproteins and lipids has not been adequately quantified.  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