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   8574篇
  免费   1440篇
  国内免费   65篇
耳鼻咽喉   236篇
儿科学   229篇
妇产科学   233篇
基础医学   760篇
口腔科学   233篇
临床医学   1579篇
内科学   1833篇
皮肤病学   156篇
神经病学   586篇
特种医学   297篇
外科学   1552篇
综合类   112篇
现状与发展   1篇
一般理论   1篇
预防医学   871篇
眼科学   211篇
药学   305篇
中国医学   33篇
肿瘤学   851篇
  2024年   47篇
  2023年   299篇
  2022年   145篇
  2021年   301篇
  2020年   355篇
  2019年   238篇
  2018年   404篇
  2017年   360篇
  2016年   437篇
  2015年   441篇
  2014年   605篇
  2013年   651篇
  2012年   556篇
  2011年   575篇
  2010年   428篇
  2009年   510篇
  2008年   450篇
  2007年   425篇
  2006年   431篇
  2005年   398篇
  2004年   342篇
  2003年   277篇
  2002年   241篇
  2001年   179篇
  2000年   161篇
  1999年   136篇
  1998年   82篇
  1997年   83篇
  1996年   50篇
  1995年   49篇
  1994年   29篇
  1993年   21篇
  1992年   52篇
  1991年   34篇
  1990年   43篇
  1989年   39篇
  1988年   46篇
  1987年   29篇
  1986年   36篇
  1985年   20篇
  1984年   13篇
  1983年   13篇
  1982年   6篇
  1981年   8篇
  1980年   4篇
  1979年   3篇
  1977年   4篇
  1975年   3篇
  1970年   3篇
  1966年   3篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
72.
73.
74.
75.
Objective : This study evaluated whether a significant reduction in unnecessary appendectomies is possible by performing diagnostic laparoscopy before appendectomy in female patients of child-bearing age, leaving behind the normal-looking appendix. Materials and methods : Sixty-one consecutive female patients between the ages of 15 and 45 years with clinical diagnosis of acute appendicitis were studied prospectively. Diagnostic laparoscopy was performed to detect whether the appendix was inflamed. The appendix was then removed and the result of laparoscopic diagnosis was matched with histological diagnosis. Results : Ten out of the 42 laparoscopically diagnosed appendicitis cases had normal appendices on histological examination. Six out of the 19 laparoscopically diagnosed normal appendices had histological evidence of appendicitis. The sensitivity of laparoscopy was 84% and the specificity was 56.5%. Conclusions : Discrepancies existed between laparoscopic appearance and histological examination in acute appendicitis. The appendices of all those with clinically suspected appendicitis should be removed and sent for histological confirmation.   相似文献   
76.
OBJECTIVE: To determine if motor vehicle collisions (MVCs) resulting in femoral fractures were associated with a different injury severity and pattern of injury compared with crashes in which victims did not sustain femoral fractures. METHODS: Retrospective review of seriously injured motor vehicle occupants admitted to a regional trauma unit (Hamilton General Hospital) during a 69-month period (April 1991 to December 1996) for whom detailed crash details were known. RESULTS: Data for 733 motor vehicle occupants with Injury Severity Scores greater than 12 were available; 112 occupants (15.3%) sustained femoral fractures, and 621 occupants (84.7%) did not sustain femoral fractures. Victims with femoral fractures had a significantly higher mean Injury Severity Score (29.4 compared with 25.3 for non-femoral fracture group; p<0.001). The femoral fracture group had a higher incidence of bowel (p<0.012) and hemopneumothorax (p<0.02) injuries as well as an increased incidence of upper and lower extremity (p<0.001) and pelvic (p<0.05) fractures. CONCLUSION: The presence of a femoral fracture is strongly associated with the pattern and severity of injuries sustained by occupants in MVCs. A high index of suspicion is warranted in identifying associated organ injuries in MVC victims with concomitant femoral fractures.  相似文献   
77.
Objectives : The study was undertaken to assess the safety and efficacy of sequential intravenous and oral ciprofloxacin in the treatment of moderate-to-severe urinary tract infections (UTI), and to identify risk factors for acquiring UTI caused by ciprofloxacin-resistant organisms. Materials and Methods : Using a prospective, open, single-centre study design, hospitalized patients with a clinical diagnosis of moderately severe UTI were enrolled. After a minimum of 3 days of intravenous ciprofloxacin, patients were switched to oral therapy. Assessment for response and analysis of risk factors were performed at the end of therapy. Results : Between December 1996 and November 1997, a total of 66 patients met the criteria for efficacy evaluation. Among the 55 patients with ciprofloxacin-sensitive organisms, 51 patients (93%) were cured. Persisting infection was noted in three patients (5%) and one patient (2%) was re-infected with a ciprofloxacin-resistant organism. Of the organisms isolated, 14 (19%) were resistant to ciprofloxacin. The presence of prostatic obstruction (odds ratio 6.02, 95% confidence interval (CI) 1.28–28.30, P = 0.02) and recurrent UTI (odds ratio 8.63, 95% CI 1.81–41.17, P = 0.007) were independently associated with infections caused by ciprofloxacin-resistant organisms. Adverse events were reported in 5 patients (8%) but no premature discontinuation or mortality was documented. Conclusion : Sequential therapy with oral therapy after initial parenteral ciprofloxacin is safe and effective in the management of moderate-to-severe UTI in appropriately selected patients.   相似文献   
78.

Summary

Compared to controls, HR-pQCT at distal radius of SLE patients on chronic glucocorticoid (SLE/GC) revealed reduced bone area, vBMD, deteriorated microarchitecture, and unevenly distributed stresses limited to cortical bone. Despite similar trabecular quality, whole bone strength decreased in patients. These alterations may partly explain high fracture rates in SLE/GC.

Introduction

To assess bone geometric, densitometric, microarchitectural, and biomechanical properties in patients with systemic lupus erythematosus (SLE) on long-term glucocorticoid (GC) (SLE/GC) as compared with healthy controls.

Methods

A total of 180 female SLE patients and 180 healthy controls were in this cross-sectional study to assess areal bone mineral density (aBMD) by dual-energy X-ray absorptiometry. High-resolution peripheral quantitative computed tomography (HR-pQCT) and microfinite element analysis (μFEA) was performed at distal radius.

Results

In addition to significantly lower aBMD at femoral neck, total hip and lumbar spine, cortical area, average volumetric BMD (vBMD) and cortical vBMD also significantly reduced by 5.3, 5.7, to 1.9 % in SLE patients, respectively. Deteriorations of cortical microarchitecture were pronounced in patients, with 6.3 % reduction in cortical thickness and 13.6 % higher in cortical porosity. Local stresses were more unevenly distributed through cortical bone in patients. SLE/GC patients had decreased whole bone stiffness, estimated failure load, and apparent modulus. Parameters related to trabecular bone density and microarchitecture were comparable between patients and controls.

Conclusion

In SLE/GC patients, despite a reduction in bone area, vBMD and deteriorated microarchitecture and unevenly distributed stresses limited to the cortical compartment, whole bone strength decreased. HR-pQCT and μFEA were promising in elucidating the potential underlying pathophysiology of bone loss and propensity to fracture in SLE/GC and provide us additional information about alterations of bone quality which might better predict fracture risk beyond aBMD in SLE/GC.  相似文献   
79.

Background

Endoscopic submucosal dissection (ESD) is a technically demanding procedure, and exposure of the submucosa depends on the action of gravity and submucosal injection. The aim of the study was to investigate the effectiveness of the Endolifter® as a traction device for enhancing submucosal visualization during ESD.

Methods

This was a prospective ex vivo comparative study conducted between September 2010 and March 2011 in the Prince of Wales Hospital. Consecutive ESDs were performed by four experienced endoscopists in an ex vivo ESD model with or without the Endolifter®. The Endolifter® allows simultaneous grasping, retracting and lifting of the mucosa during ESD, resulting in exposure of the submucosa. Each of the procedures were recorded and reviewed later by two independent assessors. The outcome measures included the proportion of time that the submucosa was visualized during the procedures (SM ratio), procedural times, perforation rates, amount of submucosal injections, and the difficulty of the procedure.

Results

Forty-eight gastric ESD procedures were performed on the model. The SM ratio was higher in the Endolifter® group (P = 0.007), particularly for lesions located at the antrum (P < 0.001). The time required for submucosal dissection and the total procedural time were also less in the Endolifter® group. The endoscopists rated the ESD procedures in the Endolifter® group as less difficult (P = 0.033).

Conclusions

The Endolifter® improved submucosal visualization during gastric ESD and reduces the difficulty of performing the procedures. The device may improve the ease of performing ESD in low-volume centers or large mucosal lesions.  相似文献   
80.
Kwok RF  Lim J  Chan MT  Gin T  Chiu WK 《Anesthesia and analgesia》2004,98(4):1044-9, table of contents
In this study, we evaluated the preemptive effect of a small dose of ketamine on postoperative wound pain. In a randomized, double-blinded, controlled trial, we compared the analgesic requirement in patients receiving preincision ketamine with ketamine after skin closure or placebo after gynecologic laparoscopic surgery. One-hundred-thirty-five patients were randomly assigned to receive preincision or postoperative ketamine 0.15 mg/kg or saline IV. Anesthetic technique was standardized. Patients were interviewed regularly up to 4 wk after surgery. Pain score, morphine consumption, side effects, and quality of recovery score were recorded. Patients receiving preincision ketamine had a lower pain score in the first 6 h after operation compared with the postoperative (P = 0.001) or placebo groups (P < 0.001). The mean (95% confidence intervals) time to first request for analgesia in the preincision group, 1.8 h (1.4-2.1), was longer than the postoperative group, 1.2 h (0.9-1.5; P < 0.001), or the placebo group, 0.7 h (0.4-0.9; P < 0.001). The mean +/- SD morphine consumption in the preincision group, 1.5 +/- 2.0 mg, was less than that in the postoperative group, 2.9 +/- 3.1 mg (P = 0.04) and the placebo group, 3.4 +/- 2.7 mg (P = 0.003). There was no significant difference among groups with respect to hemodynamic variables or side effects. No patient complained of hallucinations or nightmares. We conclude that a small dose of ketamine is not only safe, but it also provides preemptive analgesia in patients undergoing gynecologic laparoscopic surgery. IMPLICATIONS: In women undergoing laparoscopic gynecologic surgery, a small preoperative dose of ketamine (0.15 mg/kg) produced preemptive analgesia. There were no significant hemodynamic and psychological side effects with this dose.  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