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   8038篇
  免费   479篇
  国内免费   58篇
耳鼻咽喉   85篇
儿科学   177篇
妇产科学   210篇
基础医学   1080篇
口腔科学   167篇
临床医学   721篇
内科学   2007篇
皮肤病学   97篇
神经病学   802篇
特种医学   206篇
外科学   1412篇
综合类   43篇
一般理论   2篇
预防医学   246篇
眼科学   111篇
药学   511篇
  1篇
中国医学   13篇
肿瘤学   684篇
  2023年   70篇
  2022年   59篇
  2021年   219篇
  2020年   149篇
  2019年   205篇
  2018年   206篇
  2017年   133篇
  2016年   200篇
  2015年   254篇
  2014年   360篇
  2013年   389篇
  2012年   610篇
  2011年   636篇
  2010年   379篇
  2009年   311篇
  2008年   565篇
  2007年   632篇
  2006年   535篇
  2005年   511篇
  2004年   492篇
  2003年   428篇
  2002年   361篇
  2001年   64篇
  2000年   34篇
  1999年   63篇
  1998年   68篇
  1997年   54篇
  1996年   44篇
  1995年   63篇
  1994年   57篇
  1993年   46篇
  1992年   41篇
  1991年   37篇
  1990年   26篇
  1989年   24篇
  1988年   11篇
  1987年   18篇
  1986年   24篇
  1985年   22篇
  1984年   23篇
  1983年   19篇
  1982年   16篇
  1981年   12篇
  1980年   11篇
  1979年   8篇
  1978年   7篇
  1975年   9篇
  1974年   6篇
  1966年   6篇
  1908年   5篇
排序方式: 共有8575条查询结果,搜索用时 15 毫秒
1.
2.
Background::Soft tissue sarcoma (STS) is a heterogeneous group of rare neoplasms whose aetiology is largely unknown. Dioxin and dioxin-like compounds, including 2,3,7,8-tetrachlorodibenzo-p-dioxin (2,3,7,8-TCDD) and polychlorinated biphenyls (PCBs), are potential risk factors for STS.Objectives:To investigate the relation of 17 PCBs congeners, assessed in human plasma, with STS risk.Methods:We conducted a case-control study in Italy, including 52 STS cases and 99 hospital-based controls. Selected PCB were extracted by high-performance liquid chromatography (HPLC) and measured with gas chromatography-mass spectrometry (GC-MS). Odds ratios (OR), and the corresponding 95% confidence intervals (CI), were estimated through multivariate logistic regression models.Results:The most frequently detected PCB congeners were 138, 170, 180 and 149 (detected in 40-77% of controls). The OR for the sum of all 17 PCB congeners was 1.20 (95% CI 0.50-2.92). In categorical analysis no consistent association was found for individual congeners and for groups based on Wolff’s classification or the degree of chlorination. For continuous estimates, borderline positive associations emerged for Wolff’s groups 2A (OR 1.23, 95% CI 0.97-1.55), 2B (OR 1.34, 95% CI 1.00-1.77, and 3 (OR 1.19, 95% CI 0.96-1.49), for moderately (OR 1.20, 95% CI 0.96-1.51) and highly (OR 1.18, 95% CI 0.99-1.41) chlorinated PCBs, and for congeners 170 (OR 1.26, 95% CI 0.98-1.63), 180 (OR 1.26, 95% CI 0.97-1.64) and 138 (OR 1.45, 95% CI 1.02-2.04).Discussion:Most associations between PCBs and STS risk were not significant, but, given the limited sample size, we cannot exclude moderate associations.Key words: Soft tissue sarcoma, polychlorinated biphenyls, epidemiology, environmental risk factors, chemical contaminants, case-control study  相似文献   
3.
4.
5.

Introduction

Femoral neck fractures are the most frequent fractures in the elderly and hemiarthroplasty is the treatment of choice. The objective of this multicenter study is to identify predictive factors of acetabular erosion after bipolar hemiarthroplasty (surgery between 1997 and 2007) in a mobile independent population during a follow-up of ten years.

Materials and methods

Data were prospectively collected and retrospectively analyzed. Inclusion criteria were: age >60 and <85 years, BMI?<?35, normal Abbreviated MiniMental Test score, ability to walk 0.8?km and live independently, non-pathological fracture, hip with no or minimal osteoarthritic changes, and availability of clinical and radiological follow-up. For each Patient were recorded: demographic data, comorbidities, time from fracture to surgery, characteristics of the implant, duration of surgery. Patients included underwent clinical and radiological follow-up.

Results

Overall, 209 Patients met inclusion criteria. A press-fit implant was performed in 172 subjects; in contrast a cemented prosthesis was implanted in 37 patients. Nineteen patients underwent implant revision to total hip arthroplasty for acetabular erosion and pain. Classification of X-ray using Baker criteria showed a grade 0 in 54.5%, a grade 1 in 19.6%, a grade 2 in 18.1% and a grade 3 in 7.6%. Multivariate analysis revealed that the size of the femoral head (FH) was the only predictive factor of a higher risk of acetabular erosion. The Kaplan-Meier survival curve verified the risk of implant revision in Group 1 (FH sized >48?mm) and Group 2 (FH sized <48?mm). The probability of implant revision for acetabular erosion at ten years from surgery were 5.5% in Group 1 and 15.6% in Group 2.

Conclusion

In bipolar hemiarthroplasty smaller head size lead to a polar wear implying a higher risk of acetabular erosion and migration; in our population this risk was consistent with the use of implant head <48?mm diameter. Considering the absolute risk of a smaller FH size, the surgeon must evaluate the accuracy of measurement of the caliber, since the size can be significantly underestimated.  相似文献   
6.
The treatment of hammer toe has been advocated for years, and many procedures have been proposed with skeletal and soft tissue intervention. The purpose of the present study was to compare arthrodesis of the proximal interphalangeal joint with shortening osteotomy of the proximal phalanx neck. In most cases, both procedures have been associated with elongation of the extensor apparatus, capsulotomy of the metatarsophalangeal joint, and stabilization with a Kirschner wire. To experiment with a technique that respects the anatomy and joint function, we used a distal subtraction osteotomy of the proximal phalanx neck. We compared a series of 78 patients, divided in to 2 groups: 38 (48.7%) treated with arthrodesis and 40 (51.3%) with shortening osteotomy. Patients were aged 22 to 78 years, with a mean final follow-up period of 56.6 (range 24 to 96) months. For clinical evaluation, we used the American Orthopaedic Foot and Ankle Society score, Foot and Ankle Outcome Score, and a subjective rating scale. The results were comparable between the 2 techniques; however, we report faster functional recovery in the group treated with shortening osteotomy (p < .0001), with an adjunctive advantage of preserving the integrity of the proximal interphalangeal joint. Thus, according to our results, this technique is comparable to arthrodesis.  相似文献   
7.
8.
9.
BackgroundBalloon dilation and stenting of the atrial septum are techniques used to unload left heart cavities in acute or end-stage heart failure in children. However, they carry significant risks such as tamponade or device embolization.Case PresentationWe report the first case of a child with an end-stage mitochondrial cardiomyopathy on a venoarterial extracorporeal membrane oxygenator as a bridge to heart transplant where an atrial flow regulator device has been implanted.ConclusionsThis case illustrates the feasibility and safety of atrial flow regulator implantation in this setting. This procedure allowed to wean inotropic support while awaiting heart transplantation.  相似文献   
10.
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