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   5145篇
  免费   304篇
  国内免费   17篇
耳鼻咽喉   58篇
儿科学   139篇
妇产科学   96篇
基础医学   721篇
口腔科学   118篇
临床医学   400篇
内科学   1246篇
皮肤病学   149篇
神经病学   421篇
特种医学   250篇
外科学   661篇
综合类   11篇
一般理论   1篇
预防医学   244篇
眼科学   60篇
药学   415篇
中国医学   4篇
肿瘤学   472篇
  2023年   32篇
  2022年   58篇
  2021年   78篇
  2020年   60篇
  2019年   84篇
  2018年   100篇
  2017年   90篇
  2016年   99篇
  2015年   100篇
  2014年   140篇
  2013年   157篇
  2012年   303篇
  2011年   345篇
  2010年   207篇
  2009年   172篇
  2008年   302篇
  2007年   340篇
  2006年   309篇
  2005年   334篇
  2004年   258篇
  2003年   285篇
  2002年   269篇
  2001年   84篇
  2000年   105篇
  1999年   98篇
  1998年   83篇
  1997年   50篇
  1996年   50篇
  1995年   39篇
  1994年   31篇
  1993年   39篇
  1992年   69篇
  1991年   58篇
  1990年   63篇
  1989年   48篇
  1988年   31篇
  1987年   42篇
  1986年   37篇
  1985年   47篇
  1984年   51篇
  1983年   40篇
  1982年   21篇
  1981年   24篇
  1980年   25篇
  1979年   28篇
  1978年   32篇
  1977年   22篇
  1974年   15篇
  1973年   14篇
  1970年   12篇
排序方式: 共有5466条查询结果,搜索用时 15 毫秒
961.
Antiplatelet therapy is indicated for secondary prevention of ischaemic stroke. The first-line antiplatelet agent is aspirin. The effect of aspirin is, however, very limited, and this limited effect of aspirin is argued with termed 'aspirin resistance'. Strategies against aspirin resistance may include alternative use of other antiplatelet agents, combination of aspirin with other antiplatelet agents and investigation into molecular targets to develop novel antiplatelet agents. Progress in antiplatelet therapy should be directed at further reducing the risk of ischaemic events including ischaemic stroke without increasing the risk of haemorrhagic events including haemorrhagic stroke.  相似文献   
962.

Purpose:

To investigate the feasibility of targeted biopsy based on an apparent diffusion coefficient (ADC) map in the detection and localization of prostate cancer.

Materials and Methods:

This study included 288 consecutive patients with high or increasing serum prostate‐specific antigen (PSA) levels who underwent prostatic magnetic resonance imaging (MRI) examination with an ADC map. Four core‐targeted biopsies of low ADC lesions were performed under transrectal‐ultrasound guidance with reference to ADC map. The positive predictive values (PPVs) of low ADC lesions were calculated and compared for the peripheral zone (PZ), transition zone (TZ), and anterior portion, respectively. Comparisons of ADC values and sizes between malignant and nonmalignant lesions were also performed.

Results:

A total of 313 low ADC lesions were detected in 195 patients and sampled by targeted biopsies. The PPVs were 55.3% (95% confidence interval [CI]: 50–61) in total, 61.0% (95% CI: 53–69) for PZ, 50.6% (95% CI: 43–58) for TZ, and 90.9% (95% CI: 81–100) for the anterior portion. The most common nonmalignant pathology of low ADC lesions was hyperplasia, followed by chronic prostatitis. There were significant differences in ADC values and sizes between malignant and nonmalignant low ADC lesions.

Conclusion:

Targeted biopsies could be capable of detecting cancers well wherever they may be in the prostate, although the PPVs varied depending on the location of low ADC lesions. J. Magn. Reson. Imaging 2013;37:1168–1177. © 2012 Wiley Periodicals, Inc.  相似文献   
963.

Purpose

We retrospectively evaluated the clinical outcome after multidisciplinary treatment of spinal arteriovenous fistulas (AVFs) in terms of the Aminoff-Logue grading scale (ALS) to depict the outcome in a perspective pertinent to the quality of everyday living.

Materials and methods

Twenty-six spinal AVFs in 25 patients were angiographically diagnosed from April 1998 through April 2012 and treated by endovascular embolization or surgery. When both treatment procedures seemed feasible, embolization was undertaken as the initial treatment. Motor and gait disturbance at follow-up was retrospectively graded according to ALS.

Results

All lesions were localized at the thoracolumbar or sacral levels and include six epidural AVFs with intradural venous reflux, 14 dural AVFs, and six perimedullary AVFs. Embolization was performed as the initial treatment for 17 lesions, while open surgery was performed for the others as well as for residual or recurrent lesions after embolization. All lesions were completely occluded except three perimedullary AVFs. At clinical follow-up of 1–153 months (mean 53.3), amelioration of gait disturbance with reduction of ALS scores was noted for 13 lesions and amelioration of micturition for 13 lesions as well.

Conclusion

Clinical functional status was improved for half of the lesions after the multidisciplinary treatment.  相似文献   
964.
This report describes the pathologic findings for a patient with Hunter syndrome who underwent aortic valve replacement at 10 years of age, 3 years after the initiation of enzyme replacement therapy. Aortic valve pathology showed mild thickening and fibrosis as well as massive glycosaminoglycan accumulation. This suggests that enzyme replacement therapy has limited efficacy for cardiac valve disease both clinically and pathologically.  相似文献   
965.
This study aims to identify predisposing characteristics of descending necrotizing mediastinitis (DNM) arising from deep neck infection (DNI) and to determine appropriate therapeutic intervention strategies. We retrospectively reviewed 54 patients (male, n = 34; female, n = 20; mean age, 64.5 years) who had been treated at Mie University Hospital for DNI between April 2001 and October 2011. Eight of nine patients who developed DNM confirmed by computed tomography of the neck and chest, underwent mediastinal drainage (video-assisted thoracic surgical drainage, n = 6; mediastinoscopy-assisted drainage, n = 2). A patient developed uncontrolled acute respiratory distress syndrome after aggressive surgery, resulting in a mortality rate of 12 %. High blood CRP values, and the pharynx and tonsils as origins of infection were factors involved in the development of DNM arising from DNI. In conclusion, DNM remains a destructive and fatal disease that requires aggressive treatment including mediastinal exploration.  相似文献   
966.
967.
968.
969.
Basic fibroblast growth factor (bFGF) is a strong mitogen for most mesoderm- and ectoderm-derived cells. Although bFGF exists in rat and human salivary glands, its physiological role in those glands is unknown. In this study, the effects of bFGF were investigated in monolayer culture of normal rat and human submandibular gland cells. Epithelial cells from rat and human submandibular glands were cultivated with the aid of 3T3 cells as a feeder layer. The effects of different concentrations of bFGF on the second passage of these cultured cells were examined. In both the rat and human cells, the percentage of bromodeoxyuridine (BrdU)-positive cells gradually increased up to 50 ng/ml, and then increased sharply at 100 ng/ml. However, at concentrations higher than 100 ng/ml, the percentages of BrdU-positive cells reached a plateau. In both rat and human cells, total cell numbers at 100 ng/ml bFGF were significantly higher than those of the control group from culture day 4. On the other hand, the morphology of the cultured cells showed no difference either with or without bFGF. These results indicate that a major effect of bFGF on salivary gland epithelial cells is to act as a mitogenic stimulus.  相似文献   
970.
This study was performed to investigate the frequency and distribution of CD5-positive (CD5+) B cells in inflamed gingival tissues using flow cytometric and immunohistochemical analyses. The ability of CD5+ B cells to produce anti-type I collagen antibody was also examined. CD5+ B cells expressed "low" fluorescence intensity in the peripheral blood of both healthy subjects and patients with adult periodontitis. However, in inflamed gingival tissues the intensity of this surface marker was high. The percentage of B cells bearing CD5 surface marker was statistically higher in gingiva than in peripheral blood obtained from both the patients and healthy subjects. These CD5+ B cells were observed in gingival subepithelial connective tissues from the bottom to the middle of the periodontal pocket. This area showed destruction of collagen fibers and dense cell infiltrations. Anti-collagen IgG antibody level in patients' gingival crevicular fluids (GCF) was higher than that in sera from healthy subjects, and slightly higher than in autologous sera. IgM anti-collagen antibody in GCF was lower than in autologous sera and in sera from healthy subjects. EBV-transformed CD5+ B cells produced considerably more IgM and IgG antibody to collagen than CD5- B cells. Therefore CD5+ B cells may contribute to the pathogenesis of inflamed gingival tissues.  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