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   1314篇
  免费   105篇
  国内免费   28篇
儿科学   60篇
妇产科学   28篇
基础医学   140篇
口腔科学   31篇
临床医学   131篇
内科学   238篇
皮肤病学   17篇
神经病学   80篇
特种医学   130篇
外科学   212篇
综合类   53篇
一般理论   1篇
预防医学   100篇
眼科学   40篇
药学   116篇
中国医学   3篇
肿瘤学   67篇
  2022年   11篇
  2021年   20篇
  2020年   16篇
  2019年   19篇
  2018年   20篇
  2017年   15篇
  2016年   25篇
  2015年   17篇
  2014年   27篇
  2013年   46篇
  2012年   43篇
  2011年   45篇
  2010年   42篇
  2009年   46篇
  2008年   52篇
  2007年   66篇
  2006年   43篇
  2005年   42篇
  2004年   42篇
  2003年   31篇
  2002年   34篇
  2001年   28篇
  2000年   31篇
  1999年   33篇
  1998年   47篇
  1997年   58篇
  1996年   60篇
  1995年   51篇
  1994年   34篇
  1993年   37篇
  1992年   25篇
  1991年   27篇
  1990年   22篇
  1989年   36篇
  1988年   27篇
  1987年   23篇
  1986年   22篇
  1985年   23篇
  1984年   18篇
  1983年   12篇
  1982年   11篇
  1981年   7篇
  1980年   8篇
  1979年   9篇
  1978年   7篇
  1977年   11篇
  1976年   11篇
  1975年   11篇
  1971年   5篇
  1969年   7篇
排序方式: 共有1447条查询结果,搜索用时 15 毫秒
71.
The use of the Sheehan knee prosthesis extended from 1971 to 2002. It incorporated a semi-constrained hinge with intra-medullary stems cemented into the femur and tibia. While some authors have reported excellent short-term results, others have reported revision rates of up to 31% at 5–10 years. The aim of this study was to review the senior authors experience in revising these arthroplasties. We review 54 Sheehan total knee replacements and discuss the difficulties encountered during first and subsequent revisions and the often-complex reconstruction techniques used to overcome these.
Résumé Lutilisation de la prothèse de genou de type Sheehan sest étendue de 1971 à 2002. Elle comportait une charnière semi-contrainte avec des tiges intra-médullaires cimentées dans le fémur et le tibia. Tandis que dexcellents résultats à court terme ont été rapportés par quelques auteurs, un taux de révision jusquà 31% à 5–10 ans a été rapporté par dautres. Le but de cette étude était examiner lexpérience de lauteur senior dans la révision des prothèses de Sheehan. Nous avons examiné 54 prothèses et discutons les difficultés rencontrées pendant larthroplastie initiale et les révisions ultérieures ainsi que les techniques souvent complexes de reconstruction utilisées pour les mener à bien.
  相似文献   
72.
Impact of the home indoor environment on adult asthma and rhinitis   总被引:1,自引:0,他引:1  
OBJECTIVE: We sought to study the combined effects of multiple home indoor environmental exposures in adult asthma and rhinitis. METHODS: We studied 226 adults with asthma and rhinitis by structured interviews and home assessments. Environmental factors included dust allergen, endotoxin and glucan concentrations, and indoor air quality (IAQ) variables. Outcomes included forced expiratory volume in 1 second (FEV1) percent predicted, Severity of Asthma Score (SAS), Short-Form (SF)-12 Physical Component Scale (PCS), and asthma Quality of Life (QOL) score. RESULTS: House dust-associated exposures together with limited IAQ variables were related to FEV1 % predicted (R = 0.24; P = 0.0001) and SAS (R = 0.18; P = 0.007). IAQ and limited dust variables were associated with SF-12 PCS (R = 0.15; P = 0.02), but not QOL (R = 0.13; P = 0.16). CONCLUSIONS: The home environment is strongly linked to lung function, health status, and disease severity in adult asthma and rhinitis.  相似文献   
73.
OBJECTIVE: The significance of a positive apical surgical margin following radical retropubic prostatectomy has been the subject of controversy. We examined the hypothesis that a positive apical margin alone is not associated with an increased probability of biochemical relapse. MATERIAL AND METHODS: A total of 162 men underwent radical prostatectomy for clinically organ-confined disease between May 1990 and December 1998. The mean follow-up period was 55 months (minimum 24 months). The mean patient age was 60.8 years. Clinical staging was 67.9% T1 and 32.1% T2. The mean preoperative prostate-specific antigen level was 11.5 ng/ml, and the mean Gleason score was 5.8. RESULTS: Overall, 5/64 patients (7.8%) with negative surgical margins and 42/98 (42.9%) with at least one positive surgical margin had biochemical recurrence (p < 0.001). Seven of 25 patients (28%) with a solitary positive apical margin relapsed. A solitary apical positive margin was associated with a statistically significant higher risk of recurrence versus controls (p < 0.05). CONCLUSION: All patients with a positive surgical margin, including those with a solitary apical margin alone, are at significantly increased risk of biochemical failure.  相似文献   
74.
Lung heme oxygenase-1 is elevated in acute respiratory distress syndrome   总被引:6,自引:0,他引:6  
OBJECTIVE: We aimed to quantify concentrations of inducible heme oxygenase (HO)-1 in the lungs of patients with acute respiratory distress syndrome (ARDS) and to investigate its role as a source of ferrous iron and as a signaling agent for iron regulation. Control of such processes by heme oxygenase has implications for the onset, progression, and resolution of ARDS. DESIGN: Retrospective analysis of archived samples. SETTING: Adult intensive care unit of a postgraduate teaching hospital. PATIENTS: Patients admitted to the adult intensive care unit who fulfilled the American-European Consensus Conference criteria for ARDS. INTERVENTIONS: Biochemical and immunohistochemical studies using bronchoalveolar lavage fluid or lung tissue were performed in patients with established ARDS and in those undergoing lung resection (controls). MEASUREMENTS AND MAIN RESULTS: Concentrations of heme oxygenase protein were significantly elevated in lung tissue (193.7 +/- 13.27 vs. 81.0 +/- 16.0%, p < .01) and in bronchoalveolar lavage fluid (2.4 x 10(5) vs. 1.4 x 10(5) densitometric units, p = .047) taken from patients with ARDS compared with controls. Concentrations of heme oxygenase protein in bronchoalveolar lavage fluid from patients with ARDS correlated positively and significantly with changes in the concentrations of ferritin (r = .697, p = .02) and the iron saturation of transferrin (r = .8, p = .014) but correlated negatively and significantly with concentrations of bleomycin-detectable (redox-active) iron (r = -.73, p = .031). Significantly elevated (p < .05) concentrations of heme oxygenase staining in cell types expressing this protein were detected in patients with ARDS, compared with concentrations in the same cells taken from controls undergoing lung resection. CONCLUSIONS: Heme oxygenase protein is elevated in the lungs of patients with ARDS and may contribute to the changes in iron mobilization, signaling, and regulation seen in this condition.  相似文献   
75.
Background Patients with prostate cancer with a pre-operative prostate-specific antigen (PSA) τ;15ng/ml who undergo radical retropubic prostatectomy (RRP) generally do not have a good outcome, yet may have organ-confined cancer and should be offered the option of surgery. Aim To assess the outcome of patients who underwent RRP with a pre-operative PSA ≥ 15ng/ml. Methods Thirty-four patients, mean pre-operative PSA: 25.46ng/ml (15.03–76.6) and mean Gleason score: 6.4 (5–9) were assessed. Results Two groups were identified. Group I: 41% (14/34) have no biochemical recurrence to mean follow up of 58 months (30–106). Mean PSA: 18.8ng/ml (15.03–25.84). Mean Gleason score: 6.1 (5–7). Clinical stage: T1c in 80%. No patient had seminal vesicle or lymph node involvement. Group II: 59% (20/34) have biochemical recurrence or died (3) from their disease to mean follow up of 66 months (36–98). Mean PSA: 28.9ng/ml (15.28–76.6). Mean Gleason score: 6.7 (5–9). Clinical stage: T1c in 25%. Eleven patients had seminal vesicle (8) involvement or positive lymph nodes (3) or both (2). Conclusion RRP seems feasible in patients whose pre-operative PSA is between 15 and 25ng/ml with stage T1c, Gleason score ≤ 7 and negative lymph node frozen section.  相似文献   
76.
This report describes a second-generation photostimulator with four primary lights that allows independent control of the stimulation of the four receptor types in the human eye. The new design uses LEDs (with light levels controlled by eight drivers that include voltage-to-frequency converters that provide 1-micros pulses at frequencies up to 250 kHz), with four center channels being combined by use of a fiber optic assembly, and likewise for four surround channels. Four fiber optic bundles are merged into a single bundle whose output is fed into a spatial homogenizer terminated by a diffuser. An interference filter is sandwiched between each LED and the fiber optic bundle. Two camera lenses collimate light from the diffusers, one for center and one for surround. The center-surround field configuration is formed by a photometric cube with a mirrored ellipse on the hypotenuse. A field lens places images of the diffusers in the plane of an artificial pupil. The fields are highly uniform. Following alignment and calibration, the center and surround fields are indistinguishable. An observer calibration procedure, designed to compensate for prereceptoral filtering, is shown by calculation to correct also for normal observer receptoral spectral sensitivity variation. With the instrument calibrated for the individual observer, a peripherally fixated 200-ms 40% contrast rod center field pulse, highly conspicuous under dark adaptation, is invisible following light adaptation.  相似文献   
77.
78.
Data from the Scale of Prodromal Symptoms (SOPS) [Early Intervention in Psychotic Disorders, pp. 135-150] on 94 hitherto never-psychotic individuals were entered into a principal components analysis, revealing six components with an eigenvalue greater than 1.0. Based upon scree-plot analysis, further extractions were limited to three, then two, factors. Varimax rotation of the three-component extraction revealed factors with reasonable congruence with a priori content areas. All symptoms labeled as negative in the SOPS loaded on one factor, and four of five symptoms labeled as positive loaded on another. The remaining positive symptom, conceptual disorganization, has been found not to load with other positive-labeled symptoms in studies of schizophrenia using applicable instruments. All symptoms labeled as "general" in the SOPS loaded on a third factor, which appears to reflect the nonspecific psychological distress that might be expected in psychosis-na?ve individuals experiencing the preliminary stages of a serious psychiatric disorder. The independence of this component from the positive and negative symptom factors suggests that the structure obtained suggests a clinical continuity between the at-risk presentations seen in this sample and established schizophrenia.  相似文献   
79.
We report three Dutch families with familial clustering of (pre)neoplastic cervical disease, review the literature on familial risks of cervical intraepithelial neoplasia (CIN) and cervical cancer, and discuss possible practical guidelines for women with a family history of cervical cancer. Daughters and sisters of women with cervical cancer have been reported to have a relative risk of 1.5-2.3 to develop this type of cancer. From a practical clinical point of view, we suggest that as in women with an increased non-genetic risk to develop cervical cancer (e.g. because of immunosuppressive therapy) increased surveillance to detect this tumour should be considered in women with an increased risk based on family history. Cessation of smoking should be advised. As the use of condoms at least prevents HPV re-infection its use can be recommended as a way to lower the cervical cancer risk. Future studies to determine the genetic contribution to the development of cervical cancer should include the paternal family history of cancer and, because genetic predisposition might express itself as a higher risk to develop precursors of cervical cancer, carcinoma in situ and CIN grade II-III.  相似文献   
80.
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