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   10060篇
  免费   805篇
  国内免费   271篇
耳鼻咽喉   131篇
儿科学   171篇
妇产科学   76篇
基础医学   1472篇
口腔科学   182篇
临床医学   956篇
内科学   1016篇
皮肤病学   58篇
神经病学   1246篇
特种医学   629篇
外国民族医学   2篇
外科学   1841篇
综合类   1465篇
预防医学   321篇
眼科学   231篇
药学   578篇
  18篇
中国医学   432篇
肿瘤学   311篇
  2024年   40篇
  2023年   153篇
  2022年   334篇
  2021年   384篇
  2020年   403篇
  2019年   330篇
  2018年   304篇
  2017年   361篇
  2016年   386篇
  2015年   372篇
  2014年   652篇
  2013年   642篇
  2012年   624篇
  2011年   600篇
  2010年   443篇
  2009年   430篇
  2008年   425篇
  2007年   449篇
  2006年   373篇
  2005年   339篇
  2004年   318篇
  2003年   316篇
  2002年   251篇
  2001年   202篇
  2000年   165篇
  1999年   149篇
  1998年   145篇
  1997年   140篇
  1996年   134篇
  1995年   106篇
  1994年   100篇
  1993年   105篇
  1992年   84篇
  1991年   85篇
  1990年   87篇
  1989年   69篇
  1988年   49篇
  1987年   63篇
  1986年   48篇
  1985年   67篇
  1984年   64篇
  1983年   39篇
  1982年   72篇
  1981年   53篇
  1980年   51篇
  1979年   22篇
  1978年   27篇
  1977年   20篇
  1976年   20篇
  1974年   11篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.

Background

Limited data exists demonstrating the efficacy of minimally invasive surgery (MIS) compared to median sternotomy (MS) for multiple valvular disease (MVD). This systematic review and meta-analysis aims to compare operative and peri-operative outcomes of MIS vs MS in MVD.

Methods

PubMed, Ovid, and Embase were searched from inception until August 2019 for randomized and observational studies comparing MIS and MS in patients with MVD. Clinical outcomes of intra- and postoperative times, reoperation for bleeding and surgical site infection were evaluated.

Results

Five observational studies comparing 340 MIS vs 414 MS patients were eligible for qualitative and quantitative review. The quality of evidence assessed using the Newcastle-Ottawa scale was good for all included studies. Meta-analysis demonstrated increased cardiopulmonary bypass time for MIS patients (weighted mean difference [WMD], 0.487; 95% confidence interval [CI], 0.365-0.608; P < .0001). Similarly, aortic cross-clamp time was longer in patients undergoing MIS (WMD, 0.632; 95% CI, 0.509-0.755; P < .0001). No differences were found in operative mortality, reoperation for bleeding, surgical site infection, or hospital stay.

Conclusions

MIS for MVD have similar short-term outcomes compared to MS. This adds value to the use of minimally invasive methods for multivalvular surgery, despite conferring longer operative times. However, the paucity in literature and learning curve associated with MIS warrants further evidence, ideally randomized control trials, to support these findings.
  相似文献   
2.
Over the last decade, impressive technological advances have occurred in ultrasonography and small‐bowel endoscopy. Nowadays, endoscopic ultrasonography is an essential diagnostic tool and a therapeutic weapon for pancreatobiliary disorders. Capsule endoscopy and device‐assisted enteroscopy have quickly become the reference standard for the diagnosis of small‐bowel luminal diseases, thereby leading to radical changes in diagnostic and therapeutic pathways. We herein provide an up‐to‐date overview of the latest advances in endoscopic ultrasonography and small‐bowel endoscopy, focusing on the emerging paradigms and technological innovations that might improve clinical practice in the near future.  相似文献   
3.
目的探讨不同剂量骨水泥PKP联合雌激素对绝经后女性骨质疏松性腰椎体压缩性骨折患者的影响。方法选取2015年1月至2018年6月我院收治的120例老年女性骨质疏松性腰椎体压缩性骨折患者为研究对象,按行PKP手术治疗时骨水泥注入的剂量不同分为三组(A组2-4 mL、B组4-5 mL、C组5-6 mL),所有患者均随访1年,比较术后三组患者VAS评分、ODI评分、伤椎椎体前缘高度、椎体中部高度及并发症的发生率。结果三组患者相比,治疗前VAS评分、ODI评分组间比较差异无显著性(P0.05);术后3天及1年后随访时,三组患者各项指标均较治疗前显著改善,组内比较差异具有显著性(P0.05),组间比较差异无显著性(P0.05);治疗前伤椎椎体前缘高度及椎体中部高度组间比较差异无显著性(P0.05);术后3天及1年后随访时,三组患者治疗后椎体前缘、中间高度均较术前明显增加(P0.05),组间比较椎体前缘高度:C组B组A组,椎体中间高度:C组B组A组,且组间比较有统计学差异(P0.05); A组患者并发症的发生率(12.5%)明显低于B组(30.0%)、C组(41.0%),有统计学差异(P0.05)。结论 PKP术中注入小剂量骨水泥(2-4 mL)对于治疗老年女性OVCFs具有良好的治疗效果及较高的安全性。  相似文献   
4.
5.
张瑛 《中国校医》2020,34(4):284-285,288
目的比较双球囊与缩宫素用于促宫颈成熟并引产的临床效果。方法选取于2017年7月—2018年7月在本院分娩的足月妊娠孕妇100例为研究对象,随机平均分为观察组和对照组各50例,观察组采用双球囊引产,对照组采用缩宫素进行引产,对比2组孕妇的总产程、宫颈成熟度、引产成功率和新生儿Apgar评分、并发症发生率等。结果观察组促宫颈成熟有效率(100%)、引产成功率(96%)均高于对照组(82%,74%),差异均有统计学意义(P<0.05),治疗后新生儿Apgar评分、并发症发生率差异均无统计学意义(P>0.05);宫颈Bishop评分观察组(9.12±1.42)高于对照组(7.92±1.56),观察组总产程(8.23±2.54)h,对照组(13.45±3.77)h,差异均有统计学意义(P<0.05)。结论双球囊用于妊娠引产效果显著,能明显促进宫颈成熟、缩短产程,保障分娩的顺利进行,安全可靠,值得在临床中推广。  相似文献   
6.
7.

Background Context

The concept of dynamic stabilization (DS) of the lumbar spine for treatment of degenerative instability has been introduced almost two decades ago. Dynamic stabilization follows the principle of controlling movement in the coronal plane by providing load transfer of the spinal segment without fusion and, at the same time, reducing side effects such as adjacent segment disease (ASD). So far, only little is known about revision rates after DS due to ASD and screw loosening (SL).

Purpose

The present study aimed to evaluate the longitudinal revision rates following dynamic pedicle screw stabilization in the lumbar spine and to determine specific risk factors predictive for ASD, SL, and overall reoperation in a large cohort with considerable follow-up.

Design

We carried out a post hoc analysis of a prospectively collected database in a level I spine center.

Patients Example

The patient sample comprised 283 (151 female/132 male) consecutive patients suffering from painful degenerative lumbar segmental instability with or without spinal stenosis who underwent DS of the lumbar spine (Ulrich Cosmic, Ulrich Medical, Ulm, Germany) between January 2008 and December 2011.

Outcome Measures

Longitudinal reoperation rate and risk factors predictive for revision surgery were evaluated.

Methods

We analyzed the longitudinal reoperation rate due to ASD and SL and overall reoperation. Risk factors such as age, gender, body mass index, lumbar lordosis (LL), number of segments, and number of previous surgeries were taken into account. Regular and mixed model logistic regressions were performed to determine risk factors for revision surgery on a patient and on a screw level.

Results

The mean age was 65.7±10.2 years (range 31–88). One hundred thirty-two patients were stabilized in 1 segment, 134 in 2 segments, 15 in 3 segments, and 2 patients in 4 segments. Reoperation rate for ASD and SL after 1 year was 7.4 %, after 2 years was 15.0%, and after a mean follow-up of 51.4±15 months was 22.6%. Reasons for revision were SL in 19 cases (6.6%), ASD in 39 cases (13.7%), SL and ASD in 6 cases, hematoma in 2 cases (0.7%), cerebrospinal fluid fistulae in 3 cases (1.1%), infection in 6 cases (2.1%), and implant failure in 1 case (0.4%). The patients' age, the number of stabilized segments, and the number of previous surgeries and postoperative LL had a significant influence on the probability for revision surgery.

Conclusions

Reoperation rates after DS of the lumbar spine are comparable with rigid fixations. The younger the patient and the more segments are involved, the lower the LL and the more previous surgeries were found, the higher was the risk of revision. Risk of revision was almost twice as high in men compared with women. We therefore conclude that for clear clinical indication and careful evaluation of preoperative imaging data, DS using the Cosmic system seems to be a possible option. The presented data will help to further tailor indication and patient selection.  相似文献   
8.
目的:探讨椎弓根螺钉三椎体内固定对脊椎爆裂性骨折患者椎体与神经功能状态的影响.方法:选取2013年7月至2015年1月于本院进行治疗的58例脊椎爆裂性骨折患者为研究对象,对其进行回顾性研究,将其根据手术方式不同分为对照组(短节段椎弓根内固定组)29例和观察组(椎弓根螺钉三椎体内固定组)29例,然后将两组患者手术前与手术后不同时间的伤椎恢复指标与血清神经功能相关指标进行比较.结果:观察组手术后不同时间的伤椎恢复指标中的后凸Cobb角、椎体平移率、椎体高度丢失率与血清神经功能相关指标中的BDNF、NSE、NGF及S100B均显著好于同期的对照组指标,并且明显好于其治疗前,均有显著性差异(P<0.05).结论:椎弓根螺钉三椎体内固定可更为有效地恢复脊椎爆裂性骨折患者椎体参数,并且更有助于神经功能状态的恢复.  相似文献   
9.
随着对于双心疾病研究的加深,西医疗法的弊端也开始显现。而中医因其理论架构中早就有对于“心主血脉”和“心主神明”的认识,因此在双心疾病的治疗上有着先天的优势。同时近些年中医疗法的结合应用也取得不错的成绩,本文通过对于双心疾病的病例分析,来研讨这种治疗手段的合理性和先进性。  相似文献   
10.
Ewing sarcoma (ES) is a rare primary neoplasm in the lumbar adult spine and may mimic a benign tumor. In this case, after a patient's three-month history of lower back pain and rapidly progressing leg numbness and weakness, magnetic resonance imaging (MRI) showed a mass in the third lumbar vertebra. At a two-month follow-up, imaging showed a fracture, compression and lesion enlargement. Decompression and fixation confirmed ES, and the patient began combined radiotherapy and chemotherapy. Two months postoperatively, residual ES was suspected on MRI. The patient underwent a second surgery, and histopathology confirmed necrosis. A six-month follow-up after the first surgery showed no tumor recurrence. This case supports the inclusion of ES in the differential diagnosis of pathologic spinal fracture. Early decompression and spinal fixation are critical for preserving neurologic and spinal functions in ES complicated by a compression fracture. Combined adjuvant radiotherapy and chemotherapy remain the standard therapeutic strategy.  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