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   1699879篇
  免费   124039篇
  国内免费   3795篇
耳鼻咽喉   21845篇
儿科学   55855篇
妇产科学   46250篇
基础医学   241868篇
口腔科学   48808篇
临床医学   151681篇
内科学   334403篇
皮肤病学   38749篇
神经病学   131613篇
特种医学   64017篇
外国民族医学   242篇
外科学   257917篇
综合类   39031篇
现状与发展   4篇
一般理论   535篇
预防医学   124648篇
眼科学   40256篇
药学   123818篇
  7篇
中国医学   4476篇
肿瘤学   101690篇
  2021年   12854篇
  2019年   13573篇
  2018年   20015篇
  2017年   15270篇
  2016年   16674篇
  2015年   19014篇
  2014年   26313篇
  2013年   38104篇
  2012年   52937篇
  2011年   55627篇
  2010年   32882篇
  2009年   30809篇
  2008年   51714篇
  2007年   54982篇
  2006年   55453篇
  2005年   52708篇
  2004年   50924篇
  2003年   48318篇
  2002年   46525篇
  2001年   91875篇
  2000年   93704篇
  1999年   77077篇
  1998年   19759篇
  1997年   17305篇
  1996年   17445篇
  1995年   16776篇
  1994年   15326篇
  1993年   14105篇
  1992年   57508篇
  1991年   55362篇
  1990年   53060篇
  1989年   50849篇
  1988年   46211篇
  1987年   45053篇
  1986年   42317篇
  1985年   40084篇
  1984年   29429篇
  1983年   24990篇
  1982年   13949篇
  1979年   25600篇
  1978年   17627篇
  1977年   14945篇
  1976年   13917篇
  1975年   14595篇
  1974年   17682篇
  1973年   17003篇
  1972年   15718篇
  1971年   14512篇
  1970年   13468篇
  1969年   12550篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
141.
1. Effects of a novel imidazoindole derivative on cholinergic function were studied in isolated tissue preparations. 2. The compound demonstrated a dose-dependent (10(-11)-10(-9) potentiation (20-60%) of acetylcholine induced tension in guinea pig ileal tissue. 3. Increases in the size of end-plate potentials and nerve evoked muscle twitches were observed in frog nerve-skeletal muscle preparations. 4. Cholinesterase activity was not inhibited. 5. The results suggest that the compound has actions at the post-synaptic muscarinic receptor complex in smooth muscle and causes pre-synaptic increases in ACh release at the neuromuscular junction.  相似文献   
142.
We report a case of recurrent calculi in a Kock pouch continent urinary diversion. An open operation was avoided by successfully excising the Marlex mesh and removing it with the associated calculi in an endoscopic fashion.  相似文献   
143.
144.
BACKGROUND: The aim was to determine the influence of the socioeconomic status of the family and the hygienic practices in the home on the prevalence of head lice infestation in children. METHODS: The study was carried out by analyzing the answers to a standardized epidemiological questionnaire given to parents of school children aged 4-17 in Bet Shemesh, a medium-sized urban town 25 km from Jerusalem. RESULTS: Of 3,000 questionnaires distributed, 958 (31.9%) were completed and returned. The majority of the children (72.4%) had been previously infested with lice. Half of them had other family members, mainly brothers and sisters, who had been infested in the past with lice. In 97.5% of the families the mother was responsible for examining the children for lice, and for carrying out treatment when infestation was present. An association was found between presence of lice infestation and mother's education, age of child, and frequency of shampooing, combing, and examination for lice. There was no association between infestation rates and mother's country of origin, crowding in the home, and the sharing of combs, brushes, hats, scarves, towels, and clothes. CONCLUSIONS: There is evidence that the incidence of lice infestation depends on the hygienic practices in the home rather than on the socioeconomic status of the family or sharing of personal articles among family members.  相似文献   
145.
It has become common practice to rely on fitted estimates ofapparent in vivo metabolic constants (e.g., Vmax and KM) inparameterization of PBPK models. Yet, quantitative estimatesof precision in these fitted parameters are not routinely reported.Such information is needed to assess the reliability of modelpredictions. The purpose of this study was to assess the precisionin estimates of Vmax and KM for chloroform, accounting for boththe statistical uncertainties in parameter estimates from individualdata sets and any additional uncertainty due to differencesin the parameter estimates derived from various experiments.Joint confidence regions for Vmax and KM from each experiment,generated using maximum likelihood techniques, were used toevaluate these questions. Three previously published data setswere considered. Estimates of Vmax and KM obtained from thesedata sets differed more than could be explained as a consequenceof a limited number of observations, measurement error, or stochasticerror. Issues associated with the use of maximum likelihoodtechniques to estimate joint confidence regions, the estimationof metabolic constants from individual experiments within agas uptake study versus the full data set, the degree of overlapin the joint confidence regions for metabolic constants obtainedfrom separate data sets, and the implications for risk assessmentare discussed.  相似文献   
146.
147.
In contrast with cross-sectional designs used in previous studies, this exploratory study compared survey data from 127 matched pairs of clinical pharmacists and physicians working together. Physicians' perceptions of the importance of clinical pharmacy activities for patient care and the competence of pharmacists performing the activities were examined for their influence on prescribing behavior in an institutional setting. Data from a national survey showed that physicians rated pharmacists higher regarding recommendations based on drug use evaluations (p = 0.004) and competency to provide all clinical pharmacy services. Scores for pharmacokinetics ratings were similar between pharmacists and physicians (p = 0.168). Pharmacists rated the importance of recommendations based on cost-effectiveness higher than physicians (p = 0.012). Overall, physicians' perceptions of activity importance for patient care and pharmacist competency appear to dictate pharmacists' influence on physician prescribing behavior (R = 0.723).  相似文献   
148.
149.
Using hierarchical cluster analysis, applied to 47 cases of Guillain-Barre Syndrome (GBS) incident in South-West Stockholm (SWS) during the period from January 1973 to June 1992, we identified three major clinicoepidemiological subgroups. The first subgroup, 25.5% of the cases (26.7 ± 6.7 years), recorded a peak incidence at ages 20–29 years and presented significant differences from other subgroups, a high proportion of cases with onset at low age preceded by respiratory infection (83.3%) and with normal motor conduction velocity (50.0%). Also found, were less affected biological parameters, a rapidly progressive course and independence in gait at one month after onset. A second subgroup, 27.7% of cases, was severely affected, clinically and functionally. It consisted predominantly of young individuals (22.7 ± 11.1 years), with a high incidence (69.2% of cases) in autumn. A third subgroup, comprising 40.47; of cases, was older (61.1 ± 11.0 years) and, in general, also severely affected. The incidence of this form appeared to be invariant with time.  相似文献   
150.
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