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   38114篇
  免费   2463篇
  国内免费   106篇
耳鼻咽喉   295篇
儿科学   1263篇
妇产科学   1035篇
基础医学   4308篇
口腔科学   603篇
临床医学   6632篇
内科学   6712篇
皮肤病学   403篇
神经病学   3660篇
特种医学   784篇
外国民族医学   1篇
外科学   3824篇
综合类   404篇
现状与发展   1篇
一般理论   66篇
预防医学   5248篇
眼科学   495篇
药学   2282篇
中国医学   35篇
肿瘤学   2632篇
  2023年   212篇
  2022年   371篇
  2021年   695篇
  2020年   486篇
  2019年   757篇
  2018年   927篇
  2017年   638篇
  2016年   717篇
  2015年   762篇
  2014年   1139篇
  2013年   1811篇
  2012年   2552篇
  2011年   2721篇
  2010年   1450篇
  2009年   1272篇
  2008年   2473篇
  2007年   2660篇
  2006年   2478篇
  2005年   2474篇
  2004年   2300篇
  2003年   2201篇
  2002年   2113篇
  2001年   454篇
  2000年   400篇
  1999年   485篇
  1998年   450篇
  1997年   382篇
  1996年   314篇
  1995年   339篇
  1994年   276篇
  1993年   256篇
  1992年   315篇
  1991年   322篇
  1990年   308篇
  1989年   274篇
  1988年   256篇
  1987年   243篇
  1986年   215篇
  1985年   228篇
  1984年   214篇
  1983年   214篇
  1982年   205篇
  1981年   200篇
  1980年   171篇
  1979年   126篇
  1978年   141篇
  1977年   100篇
  1976年   67篇
  1975年   58篇
  1974年   66篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
OBJECTIVE: To evaluate the relative risk for peptic ulcer disease that is associated with the use of nonaspirin nonsteroidal anti-inflammatory drugs. DESIGN: Nested case-control study. SETTING: Tennessee Medicaid program. PARTICIPANTS: Medicaid enrollees 65 years of age or older were included in the study. The 1415 case patients had been hospitalized for confirmed peptic ulcer disease at some point from 1984 through 1986. The 7063 control persons represented a stratified random sample of other Medicaid enrollees. MEASUREMENTS AND MAIN RESULTS: The estimated relative risk for the development of peptic ulcer disease among current users of nonaspirin nonsteroidal anti-inflammatory drugs, compared with that among nonusers, was 4.1 (95% CI, 3.5 to 4.7). For current users, the risk increased with increasing dose, from a relative risk of 2.8 (CI, 1.8 to 4.3) for the lowest to a relative risk of 8.0 (CI, 4.4 to 14.8) for the highest dose category. The risk was greatest in the first month of use (relative risk, 7.2; CI, 4.9 to 10.5). If the association is fully causal, 29% of peptic ulcers in the study sample resulted from the use of these drugs, and the excess risk associated with such use was 17.4 hospitalizations for ulcer disease per 1000 person-years of exposure. CONCLUSIONS: These data support other findings indicating that a clinically significant risk for serious ulcer disease is associated with the use of nonaspirin nonsteroidal anti-inflammatory drugs. The data show that this risk increases with dose and recency of use and that use of these drugs may be responsible for a large proportion of peptic ulcer disease among elderly persons.  相似文献   
102.
This is the third report of a metabolic study on 56 long-term users (24 for 2-5 yr; 32 for over 5 yr) of the injectable contraceptive norethisterone enanthate (Net-En) and deals with the effects on the blood levels of lipoprotein fractions. There was no significant difference between this group and a group of 30 non-users in serum concentrations of triglycerides, total cholesterol, low density and very low density lipoproteins. There was a significant reduction in mean high density lipoprotein levels between the controls and the user groups (16% for the intermediate duration and 12% for the longer duration). Age, ethnic group, body-mass index and a close family history of cardiovascular disease were taken into account, as were various lifestyle factors: diet, exercise, alcohol consumption and smoking. In a smaller group, levels of apoproteins A and B were also assayed. There was a significant reduction in apoprotein A between controls and all users, but the significance was lost on adjusting for confounding variables. Consideration was given to the ratio of total cholesterol to high density lipoprotein cholesterol as an index of coronary risk. There were no significant differences in the total cholesterol:HDL-C ratio between controls and user groups. There was a significant interaction with ethnic group (Caucasian or Afro-Caribbean) in the response to duration of use.  相似文献   
103.
104.
Our group has previously reported significant changes in the incorporation of precursors into glycerophospholipids, particularly phosphatidylserine, in polymorphonuclear cells obtained from the peripheral blood of cluster headache patients, when compared with controls. The potential of these results led to further work using both the previous methodology and a modified isolation technique to obtain polymorphonuclear cells in as pure a state as possible. Neither the new results obtained using the original technique, nor the results with high purity polymorphonuclear cells from controls and cluster headache patients, confirm the marked changes in precursor uptake into glycerophospholipids originally reported.  相似文献   
105.
We conducted a cohort study to identify the risks and outcomes of influenza A (H3N2) pneumonia. Of the 145 patients studied, 10 (7%) had influenza A pneumonia. Logistic regression identified multiple comorbidities (P<.001) and diarrhea at the initial presentation (P=.001) as associated risks. Infection with influenza A (P=.01) and receipt of inadequate antimicrobial therapy (P=.005) were predictors of mortality.  相似文献   
106.
107.
108.
109.
As the NHS adopts an information management approach to coordinated handling of total information resources, methods of systems analysis and design require assessment to ensure that they are appropriate. Mandatory use of Structured Systems Analysis and Design Methodology (SSADM) may be encouraging a damagingly narrow view of information systems. Research is described in which an holistic view of information systems is applied, allowing the needs of information users to play a stronger role in determining how information will be supplied to them. The techniques may also assist the training activities associated with implementing new systems.  相似文献   
110.
Three patients,with known brain injury and neuropsychological impairments, are followed through an individualized cognitive rehabilitation programme and post discharge from the treatment programme. Single Photon Emission Computed Tomography (SPECT) of the brain was employed to evaluate resting relative cerebral blood flow (rCBF) during the process of recovery from brain injury. All patients experienced significant improvements on measures of neuropsychological functioning and improvements in rCBF during this longitudinal study. The specific changes in rCBF appear to be related to the location of the patient s brain injury and strategies particular to cognitive rehabilitation therapy. Continued improvements in rCBF, functional abilities, and cognitive skills were documented in these three cases up to 45 months post brain injury.  相似文献   
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