全文获取类型
收费全文 | 4787篇 |
免费 | 378篇 |
国内免费 | 113篇 |
专业分类
耳鼻咽喉 | 29篇 |
儿科学 | 31篇 |
妇产科学 | 48篇 |
基础医学 | 555篇 |
口腔科学 | 40篇 |
临床医学 | 395篇 |
内科学 | 1157篇 |
皮肤病学 | 18篇 |
神经病学 | 228篇 |
特种医学 | 97篇 |
外科学 | 462篇 |
综合类 | 697篇 |
预防医学 | 170篇 |
眼科学 | 657篇 |
药学 | 306篇 |
3篇 | |
中国医学 | 313篇 |
肿瘤学 | 72篇 |
出版年
2024年 | 17篇 |
2023年 | 83篇 |
2022年 | 160篇 |
2021年 | 230篇 |
2020年 | 237篇 |
2019年 | 212篇 |
2018年 | 266篇 |
2017年 | 209篇 |
2016年 | 225篇 |
2015年 | 192篇 |
2014年 | 391篇 |
2013年 | 356篇 |
2012年 | 276篇 |
2011年 | 265篇 |
2010年 | 215篇 |
2009年 | 217篇 |
2008年 | 195篇 |
2007年 | 159篇 |
2006年 | 170篇 |
2005年 | 149篇 |
2004年 | 110篇 |
2003年 | 107篇 |
2002年 | 86篇 |
2001年 | 90篇 |
2000年 | 53篇 |
1999年 | 53篇 |
1998年 | 40篇 |
1997年 | 43篇 |
1996年 | 51篇 |
1995年 | 46篇 |
1994年 | 35篇 |
1993年 | 34篇 |
1992年 | 27篇 |
1991年 | 19篇 |
1990年 | 17篇 |
1989年 | 10篇 |
1988年 | 22篇 |
1987年 | 23篇 |
1986年 | 16篇 |
1985年 | 29篇 |
1984年 | 30篇 |
1983年 | 24篇 |
1982年 | 18篇 |
1981年 | 14篇 |
1980年 | 21篇 |
1979年 | 14篇 |
1978年 | 5篇 |
1977年 | 9篇 |
1976年 | 6篇 |
1969年 | 1篇 |
排序方式: 共有5278条查询结果,搜索用时 15 毫秒
1.
ObjectiveEach pulmonary segment is an anatomical and functional unit. However, it is fundamentally difficult to precisely distinguish every pulmonary segment using the conventional pulmonary intersegmental planes from computed tomography images. Building arteriopulmonary segments is likely to be an effective way to identify pulmonary segments.MethodsThe thoracic computed tomography images of 40 patients were collected. The anatomic structures of interest were extracted in the transverse, sagittal, and coronal planes using the semi-automated segmentation tools provided by Amira software. The intrapulmonary vessels were subsequently segmented and reconstructed. The distributions of the pulmonary arteries, veins, and bronchi were observed. In patients with pulmonary masses, the mass was also reconstructed.ResultsThe three-dimensional reconstructed images showed the branches of the pulmonary artery ramified up to their eighth order covering the entire lung as well as evident intersegmental gaps without pulmonary arteries. The segmental artery was closely accompanied by the segmental bronchi in 486 pulmonary segments (90% of total number of segments). The size and spatial location of the pulmonary mass within a pulmonary segment were also clearly visible.ConclusionsDemarcation of arteriopulmonary segments can be used to precisely distinguish every pulmonary segment and provide its detailed anatomical structure before pulmonary segmentectomy. 相似文献
2.
3.
4.
Anna C. Rienmüller Sandro M. Krieg Franziska A. Schmidt Elias L. Meyer Bernhard Meyer 《The spine journal》2019,19(1):113-120
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5.
平板运动试验阴性患者最大ST/HR斜率对冠心病的诊断价值 总被引:3,自引:1,他引:2
目的探讨平板运动试验阴性患者最大ST/HR斜率对冠心病的诊断价值.方法选择122例平板运动试验阴性而临床有明显冠心病指征的患者进行冠状动脉造影,测定其最大ST/HR斜率.结果平板运动试验阴性患者最大ST/HR斜率诊断冠心病的敏感性为68.2%,特异性为80.8%,准确性为76.2%;运动峰值心率<预计最大心率之85%组最大ST/HR斜率诊断冠心病的敏感性为92.8%,特异性为86.7%,准确性为89.7%,高于运动峰值心率≥预计最大心率之85%组.结论平板运动试验阴性患者最大ST/HR斜率对冠心病的临床诊断有较高的敏感性、特异性和准确性,尤其是对低运动水平的患者,对减少运动试验诊断的漏诊率具有重要意义. 相似文献
6.
7.
Jhoji Tanabe Hirohiko Nakazato Hisayoshi Tanabe Hidetoshi Hanasaki Kazuo Kawasaki Daizo Yonemura 《Documenta ophthalmologica. Advances in ophthalmology》1986,63(2):165-171
The spectral response curve (amplitude versus wavelength) of the R2 of the early receptor potential (ERP) was studied in normal, protan, and deutan subjects. The R2 amplitude peaked at 520nm in most normal subjects. The R2 at long wavelengths was smaller than normal in protans and larger than normal in deutans when the maximum amplitudes were normalized to 100% at the peak. The ratio of the R2 amplitude at 460 nm to that at 600 nm clearly differed between protans and deutans. The ERP and the rapid off-response, which is mainly due to the cessation of the late receptor potential, were recorded in the same subjects. The ratio of the sensitivity of the rapid off-response at 500 nm to that at 600 nm was correlated with the ratio of the R2 amplitude at 460 nm to that at 600nm (correlation coefficient, 0.823, p < 0.001). This study, in conjunction with our previous study, indicates that the abnormality is in the outer segments of the cones in protans and deutans. 相似文献
8.
内镜下十二指肠乳头括约肌切开术治疗胆总管结石697例临床分析 总被引:6,自引:0,他引:6
目的 总结内镜下十二指肠乳头括约肌切开术治疗胆总管结石的疗效及并发症的处理经验。方法 回顾性总结了我院5年间经内镜十二指肠乳头括约肌切开术(EST)治疗胆总管结石697例的临床资料,分析临床应用的疗效及并发症的发生情况、种类、处理及预防的措施。结果 5年间697例EST取石术成功682例,成功率97.8%,并发急性胰腺炎25例(3.6%),消化道穿孔3例(0.43%),延迟出血5例(0.72%),术后胆管炎5例(0.72%),经内科保守治愈30例,外科手术治疗4例,内镜再次处理4例。结论 内镜下十二指肠乳头括约肌切开术治疗胆总管结石安全可行。熟练的内镜外科技术和丰富的开腹手术经验是完成此治疗的关键。 相似文献
9.
气功对冠心病人CM_5ST段/心率斜率的影响 总被引:1,自引:0,他引:1
37名冠心病患者随机分为气功治疗组(22人)和对照组(15人)。气功治疗组接受12周动功治疗,对照组接受安慰剂治疗,治疗前后均测定CM_5 ST段/心率斜率。结果发现动功治疗组CM_5 ST段/心率斜率减少,而对照组不变或增大,两组有显著性差异,ST段下移及常规分级运动试验其它指标在两组间无显著差异。表明CM_5ST段/心率斜率是一个敏感的心肌缺血指标。 相似文献
10.
急性心肌梗塞早期静脉溶栓治疗后,一些溶栓再通患者中,可见早期降低的ST段再度出现抬高现象。本文回顾溶栓成功者81例,其中早期出现ST段再度抬高者21例(占35%),与ST段非再度抬高者相比,CPK、CPK-MB峰值,心功能及院内死亡率等无显著差异。笔者认为,此现象也为再通的标志之一。因此,急性心肌梗塞溶栓治疗的早期连续监测心电图对确认再通与否非常重要 相似文献