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   1990254篇
  免费   134834篇
  国内免费   3736篇
耳鼻咽喉   28807篇
儿科学   66591篇
妇产科学   55584篇
基础医学   281156篇
口腔科学   54017篇
临床医学   171133篇
内科学   395195篇
皮肤病学   42534篇
神经病学   156461篇
特种医学   78745篇
外国民族医学   939篇
外科学   305676篇
综合类   43013篇
现状与发展   1篇
一般理论   594篇
预防医学   148097篇
眼科学   44668篇
药学   145310篇
  39篇
中国医学   3875篇
肿瘤学   106389篇
  2018年   20075篇
  2017年   15513篇
  2016年   16914篇
  2015年   19072篇
  2014年   26806篇
  2013年   41221篇
  2012年   56143篇
  2011年   59540篇
  2010年   35833篇
  2009年   34106篇
  2008年   56984篇
  2007年   60935篇
  2006年   61216篇
  2005年   59892篇
  2004年   58033篇
  2003年   56263篇
  2002年   55209篇
  2001年   93316篇
  2000年   96542篇
  1999年   82140篇
  1998年   22662篇
  1997年   20635篇
  1996年   20884篇
  1995年   19658篇
  1994年   18663篇
  1993年   17417篇
  1992年   64800篇
  1991年   63207篇
  1990年   61642篇
  1989年   58832篇
  1988年   54355篇
  1987年   53550篇
  1986年   50369篇
  1985年   48336篇
  1984年   36200篇
  1983年   30653篇
  1982年   18151篇
  1981年   16247篇
  1979年   32933篇
  1978年   22951篇
  1977年   19413篇
  1976年   18297篇
  1975年   19902篇
  1974年   23569篇
  1973年   22651篇
  1972年   21099篇
  1971年   19243篇
  1970年   18390篇
  1969年   16847篇
  1968年   15768篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
62.
63.
Extracellular vesicles (EV) are secreted signaling entities that enhance various pathological processes when released in response to cellular stresses. Respiratory exposures such as cigarette smoke and air pollution exert cellular stresses and are associated with an increased risk of several chronic diseases. The aim of this review was to examine the evidence that modifications in EV contribute to respiratory exposure-associated diseases. Publications were searched using PubMed and Google Scholar with the search terms (cigarette smoke OR tobacco smoke OR air pollution OR particulate matter) AND (extracellular vesicles OR exosomes OR microvesicles OR microparticles OR ectosomes). All original research articles were included and reviewed. Fifty articles were identified, most of which investigated the effect of respiratory exposures on EV release in vitro (25) and/or on circulating EV in human plasma (24). The majority of studies based their main observations on the relatively insensitive scatter-based flow cytometry of EV (29). EV induced by respiratory exposures were found to modulate inflammation (19), thrombosis (13), endothelial dysfunction (11), tissue remodeling (6), and angiogenesis (3). By influencing these processes, EV may play a key role in the development of cardiovascular diseases and chronic obstructive pulmonary disease and possibly lung cancer and allergic asthma. The current findings warrant additional research with improved methodologies to evaluate the contribution of respiratory exposure-induced EV to disease etiology, as well as their potential as biomarkers of exposure or risk and as novel targets for preventive or therapeutic strategies.  相似文献   
64.

Background

Hospitalization can contribute to insomnia in many patients and is usually treated symptomatically. However, sedative/hypnotic misuse is associated with complications in this population, especially in the elderly. Such complications include dizziness, falls and over-sedation. Due to the implicit dangers, widespread use of these drugs for insomnia, particularly in older patients, has been discouraged by many hospitals. The aim of this study was to review and evaluate prescribing patterns and to optimize the use of the sedative/hypnotic agents through daily pharmacy interventions at a community hospital.

Methods

This was a biphasic before and after study. Data on sedative/hypnotic use was collected retrospectively for a 2-month period and a sample of 100 patients was randomly selected for analysis. A 2-month prospective phase followed, in which daily orders were reviewed by one pharmacy resident and recommendations made to discontinue any unnecessary, newly prescribed sedative/hypnotic orders when appropriate. Finally, results of both phases were compared for any differences in patient demographics, being prescribed more than one sedative/hypnotic, and complications documented.

Results

During the prospective phase, pharmacist interventions led to the discontinuation of 25% of a total of 97 sedative/hypnotic orders in 97 patients. The number of patients receiving more than one sedative/hypnotic agents in the intervention group was significantly lower than the retrospective control group (15 Vs. 34, P?=?0.0026). The incidence of complications was not significantly different between the control and intervention groups for the following: over-sedation, falls and delirium (p?=?0.835, p?=?0.185, p?=?0.697, respectively).

Conclusion

This study suggests that the use of sedative/hypnotics in the inpatient units (excluding the critical care unit), is somewhat prevalent, and many patients may be on more than one sedative/hypnotic, which could potentially cause cumulative harm. During the intervention phase, 25% of the total in-hospital orders for sedative/hypnotics were discontinued following recommendations made by a pharmacist, and significantly lower number of patients receiving duplicate sedative/hypnotics was noted. Further efforts should be implemented to avoid unnecessary sedative/hypnotic initiation in hospitalized patients, and to ensure monitoring by pharmacists is optimized.  相似文献   
65.
中文:背景患者入院后可从不当消毒的环境表面获得多药耐药菌和艰难梭菌。本文确定了3种强化的终末消毒(入住同一病房的两名患者之间的消毒)策略,对感染耐甲氧西林金黄色葡萄球菌(MRSA)、耐万古霉素肠球菌(VRE)、艰难梭菌(CD)和多重耐药不动杆菌的影响。方法本文在美国东南部的9家医院开展了一项务实的、集群-随机、交叉研究。凡曾有感染或定植目标细菌感染患者居住过的病房,患者出院后随机采取4种消毒策略中的一种方法进行终末消毒:对照(季胺盐类消毒剂消毒,但凡遇到CD采用含氯消毒剂);UV(季胺盐类+UV-C消毒,但凡遇到CD采用含氯消毒剂+UV-C);含氯消毒剂;含氯消毒剂+UV-C。凡入住目标病房的患者被列为暴露人群。这4种终末消毒方法分别在每家医院连续实施7个月的周期。本文随机设计这几种消毒策略在每家医院内的实施顺序(1:1:1:1)。主要产出的结果是,观察暴露患者中目标细菌的感染的发生或定植情况,以及ITT人群中暴露患者CD感染发生率。本研究ClinicalTrials.gov注册编号:NCT01579370。结果共有31 226名患者暴露,其中21 395(69%)符合标准,包括4 916名对照组,5 178名UV组,5 438名含氯消毒剂组,以及5 863名含氯消毒剂+UV组。在对照组中,22 426个暴露日中有115名患者发生目标细菌的感染(51.3/10000暴露日)。在标准清洁策略的基础上增加UV消毒的暴露患者,其目标细菌感染的发生率明显较低(n=76;33.9/10 000暴露日;RR:0.70,95%CI:0.50~0.988;P=0.036)。含氯消毒剂组(n=101;41.6/10 000暴露日;RR:0.85,95%CI:0.69~1.04;P=0.116),或含氯消毒剂+UV组患者(n=131;45.6/10 000暴露日;RR:0.91,95%CI:0.76~1.09;P=0.303)的目标细菌的感染率,其差异无统计学意义。同样,在含氯消毒剂的基础上增加UV消毒,暴露患者中CD感染率也没有发生改变((n=38 vs 36;30.4 vs 31.6/10 000暴露日;RR:1.0,95%CI:0.57-1.75;P=0.997)。解释污染的医疗机构环境是获得病原微生物的重要来源;强化终末消毒可以降低这一风险。  相似文献   
66.
Genetically informative designs and, in particular, twin studies, are the most widely used methodology to analyse the relative contribution of genetic and environmental factors to inter-individual variability. These studies basically compare the degree of phenotypical similarity between monozygotic and dizygotic twin pairs. In addition to the traditional estimate of heritability, this kind of registry enables a wide variety of analyses which are unique due to the characteristics of the sample. The Murcia Twin Registry is population-based and focused on the analysis of health-related behaviour. The observed prevalence of health problems is comparable to that of other regional and national reference samples, which guarantees its representativeness. Overall, the characteristics of the Registry facilitate developing various types of research as well as genetically informative designs, and collaboration with different initiatives and consortia.  相似文献   
67.
Historically, no black fly (Diptera: Simuliidae) nuisance has been reported in the Murcia Region. Back in September 2016 the Ojós City Council has contacted the Regional Public Health General Directorate for help regarding a local insect nuisance, most probably based on mosquitoes. After sampling with a BG-sentinel 2 trap, collecting adult specimens with an entomological aspirator, and collect larvae and pupae on submerged giant cane stalks at the river, it turned out that Simulium sergenti was the insect species causing the nuisance. This species is not considered particularly anthropophilic; therefore, a low vector risk for human health was considered. However, the high fly density impaired the life quality of the people at the village. A management plan was recommended, treating the river with Bacillus thuringiensis var israelensis.  相似文献   
68.
69.
70.
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