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   2955篇
  免费   153篇
  国内免费   25篇
耳鼻咽喉   6篇
儿科学   195篇
妇产科学   21篇
基础医学   234篇
口腔科学   77篇
临床医学   262篇
内科学   706篇
皮肤病学   44篇
神经病学   202篇
特种医学   372篇
外科学   272篇
综合类   44篇
预防医学   131篇
眼科学   76篇
药学   177篇
  1篇
中国医学   2篇
肿瘤学   311篇
  2023年   24篇
  2022年   42篇
  2021年   80篇
  2020年   43篇
  2019年   53篇
  2018年   77篇
  2017年   47篇
  2016年   50篇
  2015年   61篇
  2014年   76篇
  2013年   119篇
  2012年   122篇
  2011年   115篇
  2010年   88篇
  2009年   128篇
  2008年   93篇
  2007年   121篇
  2006年   109篇
  2005年   102篇
  2004年   112篇
  2003年   99篇
  2002年   79篇
  2001年   37篇
  2000年   42篇
  1999年   57篇
  1998年   107篇
  1997年   125篇
  1996年   120篇
  1995年   84篇
  1994年   93篇
  1993年   102篇
  1992年   29篇
  1991年   28篇
  1990年   26篇
  1989年   51篇
  1988年   52篇
  1987年   39篇
  1986年   46篇
  1985年   43篇
  1984年   29篇
  1983年   19篇
  1982年   23篇
  1981年   37篇
  1980年   22篇
  1979年   10篇
  1978年   10篇
  1977年   24篇
  1976年   20篇
  1975年   11篇
  1973年   2篇
排序方式: 共有3133条查询结果,搜索用时 15 毫秒
1.
Birth weight on 12,644 singleton infants from 6,196 sibships born in Maryland between 1980 and 1984 were used to estimate the effects of nine maternal and infant covariates on the sibship correlation in birth weight. Assuming a homogeneous correlation across all families, the estimated intraclass correlation was 0.4664 (+/- 0.0099). This high sibship correlation makes it possible to predict, with reasonable accuracy, the birth weight of a child given information on previous sibs, as well as covariates on the mother and/or infant pertinent to a given pregnancy. The reduction in variance associated with incorporating information on the nine covariates used here was approximately equal to that obtained by conditioning on a single previous sib. Testing for heterogeneity in correlation among different groups of families showed that a crude measure of parity (first live birth vs. other), time between births, mother's marital status, and maternal age at the birth of the last child significantly influenced the sibship correlation in birth weight.  相似文献   
2.
BACKGROUND: Effects of risperidone on cognitive function in children with disruptive behavior disorders (DBDs) and subaverage intelligence quotient (IQ) were assessed. METHODS: Data from two 6-week, double-blind, placebo-controlled studies (n = 228) were combined, as were three 1-year, open-label studies (n = 688). Patients with DBDs and subaverage IQ, 5 to14 years, received placebo or risperidone .02 to .06 mg/kg/day. Cognitive measures included the Continuous Performance Task (CPT) and Verbal Learning Test for Children (VLT-C). Efficacy was assessed using the Nisonger Child Behavior Rating Form (NCBRF). Adverse events were collected via spontaneous report; sedation was assessed using visual analog scale. RESULTS: Improvements on the NCBRF Conduct Problem subscale were significantly greater for risperidone- versus placebo-treated patients (-15.8 vs. -6.4, p < .0001) in short-term studies; significant reductions were observed in long-term studies (-16.3, p < .0001). No overall decline and some significant improvement in attention (CPT) and memory (VLT-C) were noted regardless of treatment in short-term studies. VLT-C improved significantly (p < .0001) for both groups, with no difference between treatment groups. Improvements in memory (VLT-C) and attention (CPT) were noted in long-term studies. Somnolence/sedation did not affect cognitive function. CONCLUSIONS: Cognitive function was not altered by risperidone in short-term studies and was maintained or improved with one year of treatment in children with DBDs and subaverage IQ, potentially representing age-appropriate gains.  相似文献   
3.
1. The present study aimed to determine the feasibility of conducting a 5 year cardiovascular outcome trial of the treatment of 6000 elderly hypertensive patients in Australian general practices. 2. General practitioners (GPs) were invited to participate by mail and personal follow-up. Patient records were reviewed to identify subjects for a blood pressure (BP) screening programme. Blood pressure was measured on three occasions and eligible subjects were included if the average BP was 160 mmHg systolic or 90 mmHg diastolic if systolic BP was 140 mmHg. 3. Seven hundred and forty-one GPs were approached and 89 were enrolled in the study (12% of mail invites and 75% of those receiving a personal contact). In 16 practices where screening was completed, 82 000 records were reviewed to identify 4% patients eligible for screening. Twenty-two per cent of eligible subjects attended screening. Of 1938 subjects screened, 180 (9%) had BP 5=160/90 mmHg. Forty-seven percent of subjects (n = 916) were receiving antihypertensive therapy and 184 (20%) were withdrawn from therapy. One hundred and sixteen (63%) of these subjects had BP return to study entry levels within 6 weeks. Fifty-seven newly diagnosed and 81 previously treated subjects were randomized (7% of the screened population). 4. Based on the high participation rate of GPs, the response rate of patients to attend a BP screening programme and the 7% randomization to screening ratio for entry into the study, the ANBP2 pilot study has demonstrated that it is feasible to recruit subjects from Australian general practices to a cardiovascular outcome trial.  相似文献   
4.
Pediatric knee MR imaging: pattern of injuries in the immature skeleton   总被引:3,自引:0,他引:3  
  相似文献   
5.
Inflammatory myopathies like dermatomyositis are associated with increased incidence of malignancies. This association has been commonly reported with malignancies of ovaries, gastro‐intestinal tract, breast and non‐Hodgkin's lymphomas but occurrence of dermatomyositis with bladder cancer has been rarely reported. We report a patient with carcinoma bladder who developed dermatomyositis while being treated for the bladder cancer.  相似文献   
6.
7.
A comprehensive anatomic and radiographic analysis of the peribursal fat plane in 12 cadavers confirmed that the fat plane seen on radiographs represents extrasynovial fat lining the subacromial bursa and documented the anatomic relations of the bursa. A three-part retrospective clinical evaluation of rotator cuff tears, calcific tendinitis, and rheumatoid arthritis was performed. Two osteoradiologists blindly graded the appearance of the peribursal fat plane with the shoulder in external versus internal rotation in 21 patients with arthrographically intact rotator cuffs and 21 patients with disrupted rotator cuffs. The peribursal fat plane was seen better with disrupted rotator cuffs. The peribursal fat plane was seen better with the shoulder in internal rotation and was seen in 60% of control subjects but only 21% of patients with rotator cuff tears. Partial or complete obliteration of this fat plane is a sensitive (79%) but less specific (60%) indicator of rotator cuff tears. Obliteration of the peribursal fat plane by inflammatory processes in adjacent tissues, including calcific tendinitis and rheumatoid arthritis, occurred with a high frequency.  相似文献   
8.
Computed tomography (CT) was performed in 42 patients with 49 clinically suspected tears of the posterior tibial tendon. Twenty-eight of the 49 suspected tears were subsequently surgically explored and repaired. Three patterns of tendon abnormalities were recognized on CT scans: type I-intact, hypertrophied, heterogeneous tendon; type II-attenuated tendon; and type III-absence of a portion of a tendon. Types I and II correlated with partial rupture seen during surgery, and type III correlated with complete rupture of the tendon. CT findings were accurate in 96% of the patients who underwent surgery. In four cases (14%), tendon rupture was seen on CT scans, but the extent of the injury was underestimated and the rupture was misclassified. Reactive periostitis of the distal tibia was seen in 71% of diseased tendons and may represent an important factor in the diagnosis of tendon rupture.  相似文献   
9.
Scores for 112 children aged 6 to 12 years, with well-controlled seizures and of average or higher IQ, were compared for problem behavior with established norms. As assessed on the Conners' Teacher Rating Scale, the group with seizures was comparable to the normative group on two subscales and superior on two others. In contrast, parents of children in the seizure group rated them as significantly worse on all six subscales of the Revised Behavior Problem Checklist. In a larger group of 133 children with seizures, from which this sample was selected, the relationship of age, sex, and seizure type to behavior problems was examined. Subjects with partial seizures were rated as slightly more aggressive and antisocial than those with generalized seizures. Findings were discussed in regard to differences in perception of behavior by parents and teachers and the possible relevance of seizure type to the expression of behavior problems.  相似文献   
10.
OBJECTIVE: To evaluate the efficacy and risks of autologous 'blood patch' pleurodesis in patients with persistent air leak after pulmonary resection. METHODS: All patients operated on by a single surgeon between January 2002 and January 2004 and presenting with a persistent air leak after pulmonary resection have been treated by the autologous blood patch pleurodesis technique. Fifty millilitres of autologous blood were injected through the chest tube that was then rinsed, clamped for 30 min and then unclamped and placed back to water seal. RESULTS: We have obtained a 100% success rate in 11 patients with persistent air leak who have been treated with this technique over a 2-year period. Most air leaks (72.7%) ceased within 12 h of blood injection. No patient developed empyema, but two patients developed fever and pleural fluid grew Staphylococcus after blood pleurodesis. At 3-month follow-up, all patients were well and their lungs were expanded fully. CONCLUSIONS: In our experience a single injection of 50 ml of blood is sufficient to seal persistent air leaks in less than 48 h. Although highly effective, the autologous blood patch pleurodesis technique should not be used in patients with incomplete lung re-expansion or positive pleural fluid culture to minimize the risk of empyema.  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