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   8836篇
  免费   588篇
  国内免费   91篇
耳鼻咽喉   69篇
儿科学   210篇
妇产科学   399篇
基础医学   977篇
口腔科学   203篇
临床医学   1062篇
内科学   1831篇
皮肤病学   88篇
神经病学   731篇
特种医学   292篇
外科学   1163篇
综合类   233篇
一般理论   4篇
预防医学   485篇
眼科学   187篇
药学   719篇
中国医学   83篇
肿瘤学   779篇
  2023年   44篇
  2022年   105篇
  2021年   181篇
  2020年   104篇
  2019年   176篇
  2018年   209篇
  2017年   175篇
  2016年   176篇
  2015年   242篇
  2014年   284篇
  2013年   378篇
  2012年   596篇
  2011年   663篇
  2010年   415篇
  2009年   354篇
  2008年   548篇
  2007年   555篇
  2006年   582篇
  2005年   505篇
  2004年   440篇
  2003年   376篇
  2002年   333篇
  2001年   272篇
  2000年   228篇
  1999年   192篇
  1998年   73篇
  1997年   71篇
  1996年   66篇
  1995年   52篇
  1994年   39篇
  1993年   39篇
  1992年   114篇
  1991年   117篇
  1990年   97篇
  1989年   74篇
  1988年   71篇
  1987年   74篇
  1986年   47篇
  1985年   41篇
  1984年   34篇
  1983年   35篇
  1981年   24篇
  1980年   18篇
  1979年   27篇
  1978年   33篇
  1977年   18篇
  1976年   18篇
  1975年   18篇
  1974年   26篇
  1968年   18篇
排序方式: 共有9515条查询结果,搜索用时 15 毫秒
71.
72.
73.
Background: Optimal methods of preparing students for high-stakes standardized patient (SP) examinations are unknown. Purposes: The purpose is to compare the impact of two formats of a formative SP examination (Web-based vs. in-person) on scores on a subsequent high-stakes SP examination and to compare students' satisfaction with each formative examination format. Methods: Clustered randomized trial comparing a Web-based module versus in-person formative SP examination. We compared scores on a subsequent high-stakes SP examination and satisfaction. Results: Scores on the subsequent high-stakes SP examination did not differ between the two formative formats but were higher after the formative assessment than without (p < .001). Satisfaction was higher with the in-person than Web-based formative assessment format (4.00 vs. 3.62 on a 5-point scale, p = .01). Conclusions: Two formats of a formative SP examination led to equivalent improvement in scores on a subsequent high-stakes examination. Students preferred an in-person formative examination to online but were satisfied with both.  相似文献   
74.
The risks of thromboembolism following operative treatment of ankle fractures are deep vein thrombosis (DVT) and pulmonary embolism (PE). These are potentially life-threatening complications. Many orthopedic surgeons fail to appreciate the potential complications of thromboembolic events because of their rare and delayed occurrence in foot and ankle operations. The purpose of this report is to describe the potential for DVT and PE following ankle operations. We present three cases in which patients who underwent operative treatment of ankle fractures subsequently developed PE. We also review the literature on the prevalence of thrombosis, risk factors, methods of prophylaxis, and use of prophylaxis in surgical procedures of the lower extremity.  相似文献   
75.
Fang HC  Chou KJ  Chen CL  Lee PT  Chiou YH  Hung SY  Chung HM 《Nephron》2002,91(4):682-687
BACKGROUND/AIM: Uremic patients are at an increased risk of being affected by tuberculosis (TB). Periodical tuberculin skin tests were suggested to detect TB-infected patients. These were replaced by chest radiographs in endemic areas like Taiwan. However, almost 50% of the TB incidence in dialysis patients was extrapulmonary. In this study, we tried to investigate the value of tuberculin tests in dialysis patients in endemic areas. METHODS: The patients were recruited from our dialysis unit. Purified protein derivative (PPD) and control tests with antigens for Candida and toxoid were performed using the Mantoux method. PPD with >10-mm induration will be considered positive. Skin anergy meant that the indurations of all antigens were less than 5 mm. A follow-up was done 12 months after the tests. RESULTS: A total of 177 patients were evaluated. Anergy was found in 40 patients (22.6%). A positive predictor of anergy was age >45 years (p = 0.03), while a negative predictor was prealbumin >20 mg/dl (p = 0.04). Fifty-three patients (30%) had positive PPD tests. Seven of the positive PPD patients (13.2%) developed active TB during the following years. Among the 40 patients with skin anergy, 6 (15%) were found to have active TB. Of the 48 patients (21.1%) with indurations of the PPD tests between 5 and 10 mm, none was found to have active TB. CONCLUSION: Although anergy will influence the sensitivity of PPD tests, these tests in combination with anergy tests could help to establish the diagnosis of TB in uremic patients, even in TB-endemic areas.  相似文献   
76.
OBJECTIVE: Review of the results of surgical correction of atrioventricular septal defects (AVSD), identification of risk factors for mortality and failure of left AV valve repair and determination of the impact of cleft closure on postoperative AV valve function. METHODS: Between 1975 and 1995, 121 consecutive patients (55 males, 66 females) underwent surgery for biventricular correction of AVSD with a median age of 1.2 years and a median weight of 7.6 kg. Sixty-five patients had a complete AVSD, 17 patients an intermediate type, and 39 patients a partial AVSD. The left AV valve (MV) cleft was closed in 53 patients (43.8%). The mean follow-up time is 7.2+/-4.6 years. RESULTS: Actuarial survival of the whole group after 1 year was 80%, after 10 and 20 years 78 and 65%, respectively. There were 18 early deaths (7-day mortality, 10.7%; 30-day mortality, 14.9%) and eight late deaths. In a univariate analysis, risk factors for early or late death were diagnosis of complete AVSD (P=0.006), no cleft closure (P=0.024), postoperative complications (P<0.0001), age <1.2 years (P=0.017), weight <7.6 kg (P=0.002), PA/Ao pressure ratio >0.7 (P<0.0001), and ECC time >110 min (P=0.002). In the multivariate analysis, postoperative complications (P=0.003) and PA/Ao pressure ratio >0.7 (P=0.001) had parallel effects on the postoperative risk for mortality. Moderate or severe MV regurgitation was present in six patients (6.0%) in the first evaluation after discharge and in 20 patients (20.4%) in the most recent postoperative control. There were 25 reoperations in 17 patients, of which 15 had to be performed for MV regurgitation and two for MV stenosis. Freedom from reoperation was 91% at 1 year, 79% at 10 years, and 76% at 15 and 20 years. We could not identify a statistically significant risk factor for reoperation. CONCLUSIONS: In patients with AVSD of various morphologies closure of the left AV valve cleft significantly improves outcome without affecting the need for reoperation. Risk factors for early and late death (multivariate analysis) were a pulmonary/aortic pressure ratio >0.7 and the occurrence of any complication after surgery. The concept of an early surgical AVSD correction before an increase in pulmonary vascular resistance and AV valve deformations occur would represent a better surgical option than a late correction as done in our series. Early correction allows for reduction of early mortality, superior long-term survival rates and a high freedom from subsequent valve degeneration.  相似文献   
77.
The authors have shown that exogenous nitric oxide (NO) protects innervated skeletal muscle against reperfusion injury. This study further evaluated the effects of exogenous NO donor on denervated skeletal muscle. Forty-eight denervated rat cremaster muscles underwent 3 hr of ischemia, followed by 90 min of reperfusion, and received systemic infusion of 100 nmol/min s-nitroso-n-acetylcysteine (SNAC) or an equal amount of phosphate-buffered saline (PBS). Results showed that the average diameter in 10 to 20 microm arterioles was between 107 percent and 123 percent of baseline in the SNAC group, and between 55 percent and 84 percent in the PBS group during 90 min of reperfusion. These values in 21 to 40 microm and 41 to 70 microm arteries were between 100 percent and 110 percent in the SNAC group, and between 70 percent and 90 percent in the PBS group from 20 to 90 min of reperfusion. Compared to the PBS group, the SNAC group had a statistically significantly greater vessel diameter in both 10 to 20 microm (p<0.001) and 21 to 40 microm arterioles (p<0.01) during 90 min of reperfusion, and in 41 to 70 microm arteries (p<0.02) from 20 to 90 min of reperfusion. The overall blood flow of the muscle in the SNAC group increased from 37 percent of baseline at 10 min to 108 percent at 40 min of reperfusion, and remained above baseline thereafter. In contrast, this value in the PBS group was only between 27 percent and 68 percent of baseline during 90 min of reperfusion. The blood flow was statistically significantly (p<0.03) greater in the SNAC group than in the PBS group from 40 to 90 min of reperfusion. Among the conclusions were: (1) NO donor SNAC improves the microcirculation of denervated skeletal muscle during early reperfusion; and (2) this protection against reperfusion injury is independent of innervation in skeletal muscle.  相似文献   
78.
儿童颈椎间盘钙化的诊断和治疗   总被引:2,自引:0,他引:2  
Xu H  Wang Y  Chou K  Jin S  Zhao Q  Fei Q 《中华外科杂志》2002,40(2):124-126,T004
目的 探讨儿童颈椎间盘钙化诊断和治疗的有效方法。方法 回顾性分析13例儿童的颈椎间盘钙化,其中上感后颈痛5例,外伤后偶然发现2例,突发颈部疼痛3例,突发斜颈3例。所有患者均经颈椎正、侧位X片证实。伴有疼痛症状应用非甾体抗炎镇痛药类药物,对于颈部症状较重则予预围外固定或短暂牵引后颈围外固定3-4周。结果 13例患儿共发现14个椎间隙的颈椎间盘钙化。经对症处理后临床症状均消失,所有的钙化均于5个月内完全消失。结论 儿童颈椎间盘钙化是一良性自限性疾病,正确认识其病理生理过程,可避免不必要的手术创伤。  相似文献   
79.
Lin TS  Chou MC 《Surgical endoscopy》2002,16(7):1055-1058
BACKGROUND: Endoscopic thoracic sympathectomy or sympathicotomy of the lower part of the stellate ganglion is an efficient method for the treatment of craniofacial hyperhidrosis, but postoperative compensatory sweating may be troublesome in some patients. Needlescopic thoracic sympathetic block by clipping may achieve a similar effect as well as providing a possible reverse operation for patients who suffer from intolerable postoperative compensatory sweating. METHODS: Between January 1998 and June 2000, we collected a total of 28 patients with craniofacial hyperhidrosis. There were 15 men and 13 women with a mean age of 39.2 years (ranges, 19-50). All patients were placed under single-lumen intubated anesthesia in a semisitting position. Two ports were needed. We used a 2-mm 0 degrees thoracoscope and endo clips to perform a sympathetic block by clipping the lower third of the stellate ganglion at the second intercostal space. RESULTS: The operation was usually accomplished within 20 min (ranges, 15-30). All patients were discharged within 4 h after the operation. There were no surgical complications or surgical mortality cases. All patients achieved improvement of craniofacial hyperhidrosis without recurrent symptoms after a mean of 25.3 months (range, 12-41) of follow-up. Twenty-five patients (85.7%) developed compensatory sweating of the trunk and lower limbs. One of these patients could not tolerate this postoperative sweating; he therefore underwent a reverse operation and obtained improvement of the compensatory sweating 18 days after removal of the endo clips. CONCLUSION: Needlescopic thoracic sympathetic block by clipping is a safe and effective method for the treatment of craniofacial hyperhidrosis; compensatory sweating may be improved after a reverse operation and removal of the endo clips.  相似文献   
80.

Introduction

Heart transplantation has become the best available therapy for patients with refractory end-stage heart failure. Cyclosporine (CsA) and mycophenolate mofetil (MMF) are the 2 FDA-approved drugs to prevent posttransplant acute rejection episodes. The purpose of this study was to evaluate the result of heart transplantation treated with CsA and everolimus (EVL), compared with that of patients treated with CsA and MMF.

Materials and Methods

From 2000 to 2009 heart transplantation was performed in 239 patients among whom we enrolled 93 patients with a serum creatinine values ≤2.8 mg/dL after informed written consents. The 2 arms were a CE group, who received EVL (n = 46) CsA, and steroid (n = 46), and a CM group who received MMF, CsA, and steroid (n = 47).

Results

There was no operative mortality in either groups. The 1- and 5-year survivals of the CE group were 97.67 ± 2.22% and 80.23 ± 6.87%, versus the CM group, 97.72 ± 2.17% and 79.38 ± 7.62%, respectively. There was significant difference between the 2 groups.

Conclusion

Survival after heart transplantation under EVL or MMF plus CsA and steroid was good. The survival of patients under the regimen of EVL, CsA and, steroid was not inferior to that of subjects prescribed MMF, CsA and steroid up to 5 years.  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