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   100989篇
  免费   6156篇
  国内免费   449篇
耳鼻咽喉   1114篇
儿科学   2527篇
妇产科学   1787篇
基础医学   12503篇
口腔科学   1777篇
临床医学   10705篇
内科学   20354篇
皮肤病学   1342篇
神经病学   10088篇
特种医学   3972篇
外国民族医学   3篇
外科学   16358篇
综合类   1101篇
一般理论   131篇
预防医学   8244篇
眼科学   2081篇
药学   6505篇
中国医学   106篇
肿瘤学   6896篇
  2023年   567篇
  2022年   939篇
  2021年   2099篇
  2020年   1330篇
  2019年   2103篇
  2018年   2556篇
  2017年   1828篇
  2016年   1997篇
  2015年   2279篇
  2014年   3451篇
  2013年   4740篇
  2012年   7565篇
  2011年   7980篇
  2010年   4600篇
  2009年   4153篇
  2008年   7130篇
  2007年   7465篇
  2006年   7180篇
  2005年   6892篇
  2004年   6720篇
  2003年   6051篇
  2002年   5706篇
  2001年   841篇
  2000年   556篇
  1999年   894篇
  1998年   1249篇
  1997年   954篇
  1996年   778篇
  1995年   707篇
  1994年   606篇
  1993年   597篇
  1992年   447篇
  1991年   402篇
  1990年   333篇
  1989年   303篇
  1988年   291篇
  1987年   294篇
  1986年   247篇
  1985年   281篇
  1984年   307篇
  1983年   253篇
  1982年   335篇
  1981年   283篇
  1980年   224篇
  1979年   94篇
  1978年   128篇
  1977年   111篇
  1976年   81篇
  1975年   69篇
  1973年   69篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
101.
Dental treatment is a dyadic encounter. Yet research on the dentist-patient dyad has tended to focus on patient perceptions of dentist, to the neglect of dentist perceptions of patient. Previous theoretic and qualitative work on caregiver perceptions of patients suggested three dimensions of evaluation. Dentists (N=618) rated their patients on items taken from two prior studies. Dentists' responses were subjected to confirmatory factor analysis. The analysis substantiated the existence of three evaluative dimensions: compliance, tractability, and likability. Further analysis showed that the three dimensions formed a Guttman simplex, revealing a second-order factor of selectivity and allowing a classification of dentists on the basis of patient selectivity.This study was funded by a grant from the University of Connecticut Research Foundation.  相似文献   
102.
Coeliac disease has been associated with a variety of neurological conditions, most frequently cerebellar ataxia and peripheral neuropathy. To date, chorea has not been associated with coeliac disease. We present the case histories of 4 individuals with coeliac disease and chorea (4 women, average age of onset of chorea 61 years). Unexpectedly, most of these patients showed a notable improvement in their motor symptoms after the introduction of a gluten-free diet.  相似文献   
103.
104.
BACKGROUND: Repetitive transcranial magnetic stimulation (rTMS) affects the excitability of the motor cortex and is thought to influence activity in other brain areas as well. We combined the administration of varying intensities of 1-Hz rTMS of the motor cortex with simultaneous positron emission tomography (PET) to delineate local and distant effects on brain activity. METHODS: Ten healthy subjects received 1-Hz rTMS to the optimal position over motor cortex (M1) for producing a twitch in the right hand at 80, 90, 100, 110, and 120% of the twitch threshold, while regional cerebral blood flow (rCBF) was measured using H(2)(15)O and PET. Repetitive transcranial magnetic stimulation (rTMS) was delivered in 75-pulse trains at each intensity every 10 min through a figure-eight coil. The regional relationship of stimulation intensity to normalized rCBF was assessed statistically. RESULTS: Intensity-dependent rCBF increases were produced under the M1 stimulation site in ipsilateral primary auditory cortex, contralateral cerebellum, and bilateral putamen, insula, and red nucleus. Intensity-dependent reductions in rCBF occurred in contralateral frontal and parietal cortices and bilateral anterior cingulate gyrus and occipital cortex. CONCLUSIONS: This study demonstrates that 1-Hz rTMS delivered to the primary motor cortex (M1) produces intensity-dependent increases in brain activity locally and has associated effects in distant sites with known connections to M1.  相似文献   
105.
OBJECTIVE: The surgical results for the repair of interrupted aortic arch (IAA) have evolved in recent years. We report our results for staged repair of this complex congenital malformation. METHODS: Sixty-five patients (mean age, 16.9+/-41.7 days) were diagnosed with IAA and referred for surgical therapy. The surgical management strategy at our institution between 1982 and 2005 has been one-stage complete repair (n=13) or staged repair (n=52) in selected patients. Non-complex patients (group I, n=51) had a ventricular septal defect (87%), aortopulmonary window (8%), and left ventricular outflow tract obstruction (27%). Group II (n=14) were patients with Taussig-Bing double outlet right ventricle (n=6) or truncus arteriosus (n=8). Method of staged repair of IAA was to transect and turn down the left carotid artery and anastomosis it to the descending aorta (n=41) or graft interposition (n=2) combined with a pulmonary artery (PA) banding followed in a few months by delayed ventricular septal defect (VSD) closure and PA de-banding. RESULTS: There were 5 early and 10 late deaths. The actuarial survival including early mortality was 92% at 1 year, 81% at 5 years, and 76% at 10 and 15 years. There was an 81% 15-year survival for children in group I compared with a 54% for children in group II (p<0.001). Risk factors for increased mortality by univariate analysis were as follows: (1) primary aortic anastomosis (p=0.03), (2) presence of complex anomalies (p=0.05), and (3) initial IAA repair performed before 1994 (p=0.05). Actuarial freedom from any type of aortic reoperation or intervention was 86% at 1 year, 69% at 5 years, and 60% at 10 and 15 years. Univariate and multivariate analyses identified no tested variables as risk factors for reoperation. The majority (86%) was in New York Heart Association (NYHA) class I, and 14% remained in NYHA class II. During the postoperative course there were no neurologic deficits, seizures, and growth disturbances in any patient. CONCLUSION: Staged repair of IAA using a left carotid artery turn down can be safely applied in IAA patients with and without other intracardiac anomalies with good results. Use of the left carotid artery for arch reconstruction did not result in any detectable neurological events or growth disturbances later in life. Associated anomalies played an important role in outcomes. The long-term probability for reoperation and/or reintervention remains high regardless of operative technique.  相似文献   
106.
107.
Recent media depictions of the dangers of biomedical research have fueled public and regulatory scrutiny of academic research institutions. The authors argue that if these institutions are to preserve the trust that the public has historically bestowed upon them, they must go beyond mere compliance with regulatory mandates. Several steps are suggested that institutions can take to strengthen and supplement ongoing compliance efforts, steps the authors believe will bolster the public's confidence in the integrity of academic research institutions. These steps grow out of the authors' analysis of three key components of institutional trustworthiness: (1) shared goals between research institutions and the communities they serve, (2) robust institutional oversight of research activities, and (3) training programs that build professional character. The authors' recommendations include the use of research advisory councils to assure the public that research goals reflect community interests, more collaborative relationships between institutional review boards and members of investigative teams, and educational programs that emphasize the importance of professional integrity in biomedical research. These efforts will help preserve public confidence that an institution's research priorities are appropriate and that the research it conducts is ethical. Preserving this public trust is central to the long-term success of biomedical research and the institutions in which such research takes place.  相似文献   
108.
1. The pharmacokinetics of Dalal-peptide T-NH2 (peptide T) was determined during phase I clinical trials in patients with acquired immunodeficiecy disease (AIDS) and AIDS related complex (ARC). Drug levels were determined by specific RIA, and in some cases with HPLC analysis, after intraveneous (i.v.) or intranasal (i.n.), via metered sprayer, administration.

2. The plasma kinetics appeared to be bi-phasic with a first compartment half-life of 30 to 60 minutes and a second plasma clearence rate of 4 to 6 hours, observed for both routes of administration. Peptide T, in one individual was confirmed to be present at 6 hrs in plasma, determined after HPLC isolation followed by specific RIA.

3. Bioavailabilty, determined for a 2 mg test dose in six individuals was 9.3 ± 6.9 nmol/L. Peak plasma levels of 41 ± 30 nmol/L after 10 mg i.n., 2.8 ± 5.9 nmol/L after 2mg i.n., and 0.13 ± 0.07 nmol/L after 0.4 mg i.n. were observed. In two individuals tested, peptide T was detected in CSF at levels 20% of the corresponding plasma level 90 and 145 minutes post i.v. administration. Peptide T was not detected in urine. I.N. administration was well tolerated for times up to 21 months.  相似文献   

109.
A case of true conversive hallucinations in a 19-year-old female soldier is described. This phenomenon is rare and should be distinguished from psychotic or dissociative states.  相似文献   
110.
Perceived control of asthma and quality of life among adults with asthma.   总被引:3,自引:0,他引:3  
BACKGROUND: Perceived control of certain chronic conditions influences health status outcomes. OBJECTIVE: To explore the impact of perceived control of asthma on asthma-specific and generic health status outcomes among adults with asthma. Perceived control was defined as individuals' perceptions of their ability to deal with asthma and its exacerbations. METHODS: Data were drawn from the baseline and first two followups of a longitudinal study of adults with asthma surveyed by telephone at 18-month intervals. An 11-item questionnaire (Perceived Control of Asthma Questionnaire [PCAQ]) was developed and validated. RESULTS: The PCAQ demonstrated high internal consistency (Cronbach's alpha = 0.79). Greater perceived control was associated with less severe asthma, greater asthma self-efficacy, lower perceived asthma severity, lower perceived danger from asthma, and greater perceived usefulness of asthma medicines. Greater perceived control was significantly associated with better asthma-specific quality of life concurrently and 18 and 36 months later, after controlling for demographics, smoking, and severity of asthma. Greater perceived control as also significantly associated with generic mental health outcomes concurrently and 18 and 36 months later, after controlling for covariates. Perceived control was associated with physical function concurrently and 18 months later, but not 36 months later. CONCLUSIONS: The PCAQ is a reliable and valid measure of perceived control of asthma. Perceived control of asthma was associated with both asthma-specific and generic health status outcomes, concurrently and predictively. If perceived control could be modified, better outcomes, particularly better psychologic outcomes, might be achieved for individuals with asthma.  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