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   20142篇
  免费   1533篇
  国内免费   51篇
耳鼻咽喉   127篇
儿科学   605篇
妇产科学   548篇
基础医学   2954篇
口腔科学   355篇
临床医学   2289篇
内科学   3993篇
皮肤病学   346篇
神经病学   2095篇
特种医学   650篇
外科学   1897篇
综合类   200篇
现状与发展   1篇
一般理论   24篇
预防医学   2165篇
眼科学   377篇
药学   1596篇
中国医学   63篇
肿瘤学   1441篇
  2024年   27篇
  2023年   254篇
  2022年   407篇
  2021年   714篇
  2020年   493篇
  2019年   763篇
  2018年   751篇
  2017年   603篇
  2016年   598篇
  2015年   666篇
  2014年   857篇
  2013年   1104篇
  2012年   1767篇
  2011年   1656篇
  2010年   863篇
  2009年   810篇
  2008年   1326篇
  2007年   1322篇
  2006年   1100篇
  2005年   1171篇
  2004年   1020篇
  2003年   876篇
  2002年   836篇
  2001年   141篇
  2000年   95篇
  1999年   125篇
  1998年   140篇
  1997年   134篇
  1996年   83篇
  1995年   78篇
  1994年   75篇
  1993年   69篇
  1992年   66篇
  1991年   56篇
  1990年   70篇
  1989年   58篇
  1988年   50篇
  1987年   49篇
  1986年   56篇
  1985年   37篇
  1984年   33篇
  1983年   26篇
  1982年   41篇
  1981年   31篇
  1980年   22篇
  1979年   19篇
  1978年   19篇
  1977年   20篇
  1973年   15篇
  1972年   13篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
21.
22.
The Proxemics/Activity test and the Eat/Drink test, two components of the Anxiety/Defense Test Battery, were developed to measure defensive reactions to situations associated with a natural predator (cat). In the present studies the behavioral effects of 8-OH-DPAT treatment (0.01–1.0 mg/kg, SC) were entirely consistent with anxiety/fear reduction. These effects included an increase in time spent near the cat compartment, and a complimentary decrease in time spent farthest from this compartment, together with an increase in transits and locomote behavior. 8-OH-DPAT (1.0 mg/kg) also increased eat frequencies and durations (highly preferred food) both during and following cat presentation, without influencing drinking. This finding is discussed with reference to previous findings with 8-OH-DPAT in studies assessing both food intake and anxiolysis. Interestingly, 8-OH-DPAT was more potent in a majority of its effects in female subjects, a finding consistent with recent neurochemical data. These findings provide important behavioral evidence for a sexual differentiation in 5-HT function, and support the case for greater emphasis on female subjects in animal models of anxiety.Supported by NIH MH42803 and RCMI Grants RR03061 and RR01825  相似文献   
23.
24.
This article highlights positive outcomes for a convenience sample of six women (49-64 years of age) with fibromyalgia syndrome (FMS) who participated in an exercise program over 5 years. This group showed improvement with various FMS symptoms,fitness, and psychosocial factors early in the program, then showed further improvement as a result of adding new exercises to the protocol during the fourth and fifth years. Data suggest that certain people with FMS can improve their functional capacity with exercise over time, and move to even higher levels of physical function while aging and coping with FMS. Practical advice is provided for rehabilitation nurses regarding exercise and FMS.  相似文献   
25.
Prognostic factors in diffuse proliferative lupus glomerulonephritis   总被引:4,自引:0,他引:4  
A number of clinical laboratory and biopsy-derived parameters were assessed for their prognostic significance in the short (24 months), intermediate (60 months) and long terms in 45 patients (43 female, 2 male) with diffuse proliferative lupus glomerulonephritis (DPGN). The factors evaluated were serum creatinine (SCr) and urinary protein at time of biopsy, initial dose of prednisone and immunosuppressive after biopsy, activity index (AI), chronicity index (CI), their individual components, extent of extraglomerular (tubulo-interstitial) immune deposits (EGD) and mean number of intraglomerular monocytes per glomerulus (NSE index). Using proportional hazards analysis to evaluate the parameters, SCr (P = 0.003), AI (P = 0.005) and NSE index (P = 0.038) were shown to be significant predictors of outcome when all variables except the components of AI and CI were considered. When AI and CI were omitted but their components included, SCr (P = 0.0005), NSE index (P = 0.024), extent of karyorrhexis (P = 0.035) and glomerulosclerosis (P = 0.033) were then demonstrated to be significant prognostic factors of DPGN. The results suggest that intraglomerular monocyte infiltration has a protective effect and confirm that AI index is a relatively powerful predictor of outcome. Histologic and nonhistologic biopsy factors contribute significant additional prognostic information to that provided by SCr.  相似文献   
26.
BACKGROUND: Thiazolidinediones (TZD) have been reported to improve early stages of diabetic nephropathy independent of glycaemic control. Since blockade of the renin-angiotensin system (RAS) is known to reduce the risk of nephropathy, we hypothesised that the renal effect of TZDs might be related to a favourable effect on the intrarenal RAS. We aimed to determine if the TZD rosiglitazone could reduce RAS activation. METHODS: We studied adult type 2 diabetic patients and placed them on rosiglitazone for three months. We have previously used the renal haemodynamic response to angiotensin-converting enzyme (ACE) inhibition to demonstrate the state of RAS activation, and thus measured renal plasma flow (RPF) and glomerular filtration rate (GFR) before and after administration of captopril at 0 month and at three months. Plasma renin activity (PRA), active renin, aldosterone and natriuretic peptides were analysed. RESULTS: The RPF response to ACE inhibition was not altered. There was no change in GFR, PRA, active renin and aldosterone levels. Two patients developed oedema one had an elevated baseline active renin and another had an elevated baseline aldosterone level. CONCLUSION: The favourable effects of TZDs on diabetic nephropathy is likely not related to an influence on the RAS.  相似文献   
27.
Increase in plasma beta endorphins precedes vasodepressor syncope.   总被引:1,自引:1,他引:0       下载免费PDF全文
BACKGROUND--Endogenous opioids have a tonic inhibitory effect on sympathetic tone and have been implicated in the pathophysiology of vasodepressor syncope. Plasma beta endorphin concentrations increase after vasodepressor syncope induced by exercise or by fasting. AIMS--To take frequent samples for plasma beta endorphin estimation during tilt testing, and to determine whether plasma beta endorphin increased before the start of syncope. PATIENTS--24 patients undergoing tilt testing for investigation of unexplained syncope. SETTING--Tertiary referral centre. METHODS--Blood samples were obtained during 70 degrees head up tilt testing. Plasma beta endorphin concentrations were estimated by radioimmunoassay (mean(SD) pmol/l). RESULTS--Patients with a positive test showed a rise in beta endorphin concentrations before syncope baseline 4.4(1.5) v start of syncope 8.5(3.1), p < 0.002). In contrast, patients with a negative test showed no change in beta endorphin concentrations (baseline 3.4(1.0) v end of test 4.5(2.3), NS). After syncope all patients showed a large secondary increase in beta endorphins (32.3(18.6)). CONCLUSION--An increase in plasma beta endorphins precedes vasodepressor syncope. This finding supports a pathophysiological role for endogenous opioids.  相似文献   
28.
Data from the National Institute of Mental Health (NIMH) Epidemiologic Catchment Area Program, an epidemiologic survey of five communities, showed that four major disorders commonly begin in late adolescence or young adulthood. The median age at onset for anxiety disorders is 15 years; for major depressive episode, 24 years; for drug abuse or dependence, 19 years; and for alcohol abuse or dependence, 21 years. Findings also suggest that for respondents 18-30 years old, having a major depressive episode or anxiety disorder doubles the risk for later drug abuse or dependence.  相似文献   
29.
BACKGROUND: Providing patients with an audiotape of their medical consultation has been a relatively common practice in oncology clinics for some years. However, broader generalisability of the technique has yet to be examined. AIMS: To investigate the efficacy of providing patients with an audiotape of their consultation in a general practice setting. DESIGN OF STUDY: Randomised controlled trial: 95 experimental participants, 85 controls. SETTING: Routine surgeries run by two general practitioners (GPs) in two different health centres. METHOD: All patients attending GP appointments were eligible for inclusion. Patients were followed up by telephone 7-10 days later. RESULTS: More than half (61%) of the patients who received a tape listened to it. Among listeners, 64% rated the tape useful or very useful; 24% noticed information not heard in the consultation. Half of listeners (46%) said that their understanding of the consultation improved after listening to the tape. Half of the listeners (48%) shared the tape with others, of whom 71% found sharing helpful or very helpful. However, 21% of those who shared the information with others found this unhelpful or very unhelpful, suggesting that patients may need to be briefed on the potential risks of sharing. At follow-up a week later, it emerged that being given a tape had no effect on adherence with GPs' advice, nor on anxiety about conditions. CONCLUSION: Providing patients with an audiotape of their GP consultation was positively rated by many patients. Although there were no detectable clinical effects at follow-up, the technique merits further evaluation in general practice.  相似文献   
30.
BACKGROUND AND AIMS: The aim of this work was to test the feasibility of using a bipolar low thermal acting system inducing collagenic sealing but not protein coagulation to secure hepatic parenchyma cutting. MATERIALS AND METHODS: Thirty consecutive hepatectomies were carried out using kellyclasy plus ligatures and clips (controls), while the following 50 hepatectomies used kellyclasy plus bipolar vessels sealer (BVS). Blood loss, duration of hepatic pedicle clamping, length of hospital stay, and complications were recorded. RESULTS: There was no statistically significant difference in blood loss and duration of clamping between controls and BVS. Specific complications (9/21 in the control group vs 1/49 for the BVS group, p<0.00045) and length of hospital stay (14 days in the control group vs 11 days in the BVS group, p<0.014) were statistically lower in BVS group than in the controls, mainly due to prevention of bile duct leakages. CONCLUSIONS: Our data suggest that BVS may be particularly efficient to achieve bilistasis leading to the highest level of safety in performing hepatectomies. Further studies are now needed to confirm its superiority on the classical biliary ducts occlusion techniques.  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