全文获取类型
收费全文 | 14283篇 |
免费 | 1191篇 |
国内免费 | 268篇 |
专业分类
耳鼻咽喉 | 216篇 |
儿科学 | 181篇 |
妇产科学 | 129篇 |
基础医学 | 1647篇 |
口腔科学 | 817篇 |
临床医学 | 1784篇 |
内科学 | 1291篇 |
皮肤病学 | 116篇 |
神经病学 | 724篇 |
特种医学 | 1005篇 |
外科学 | 2026篇 |
综合类 | 1259篇 |
预防医学 | 2037篇 |
眼科学 | 1517篇 |
药学 | 568篇 |
4篇 | |
中国医学 | 205篇 |
肿瘤学 | 216篇 |
出版年
2024年 | 39篇 |
2023年 | 279篇 |
2022年 | 532篇 |
2021年 | 623篇 |
2020年 | 574篇 |
2019年 | 598篇 |
2018年 | 590篇 |
2017年 | 513篇 |
2016年 | 527篇 |
2015年 | 470篇 |
2014年 | 828篇 |
2013年 | 1092篇 |
2012年 | 648篇 |
2011年 | 668篇 |
2010年 | 607篇 |
2009年 | 576篇 |
2008年 | 624篇 |
2007年 | 648篇 |
2006年 | 567篇 |
2005年 | 510篇 |
2004年 | 453篇 |
2003年 | 385篇 |
2002年 | 348篇 |
2001年 | 322篇 |
2000年 | 250篇 |
1999年 | 228篇 |
1998年 | 208篇 |
1997年 | 208篇 |
1996年 | 210篇 |
1995年 | 168篇 |
1994年 | 137篇 |
1993年 | 133篇 |
1992年 | 127篇 |
1991年 | 108篇 |
1990年 | 83篇 |
1989年 | 71篇 |
1988年 | 82篇 |
1987年 | 69篇 |
1986年 | 63篇 |
1985年 | 72篇 |
1984年 | 82篇 |
1983年 | 61篇 |
1982年 | 55篇 |
1981年 | 55篇 |
1980年 | 38篇 |
1979年 | 29篇 |
1978年 | 41篇 |
1977年 | 37篇 |
1976年 | 43篇 |
1975年 | 29篇 |
排序方式: 共有10000条查询结果,搜索用时 658 毫秒
41.
A simple method for collection and measurement of the progressive motility of spermatozoa was developed. The procedure consists of the spectrophotometric measurement of the increase in optical absorbance produced by the upward migration of spermatozoa in a high density medium of Ficoll 400. The suspension containing migrated spermatozoa may be used as a purified population of uniformly motile and undamaged spermatozoa. 相似文献
42.
Purpose : To compare the clinical application value of Ultrasound biomicrsocpic dark room provocative test with the traditional dark room test in screening primary angle closure glaucoma (PACG).Methods: 22 eyes with PACG in prodromal stage and 30 eyes with deep anterior chamber and wide angle of 15 normal persons were observed in this trail. All 52 eyes were performed traditional dark room provocative test and ultrasound biomicorosopic darkroom test respectively. With different positive diagnostic criteria, the sensitivity of the two methods were compared using chi-squared analysis.Results : After staying in the dark room for 2 hours, In case group, IOP in 10 of 22 eyes rose more than 1. 07kPa(1kPa = 7.5mmHg), in 12 eyes less than 1.07kPa or had no changes; appositional angle closure were found by Goldmann gonioscopy in 8 eyes : 3 eyes in two quadrants, 5 eyes in more than two quadrants; the appositional angle closure was found by UBM in 15 eyes; 3 eyes in one quadrants, 5 eyes in two quadrants, 7 eyes 相似文献
43.
Image processing is a critical part of obtaining high-quality digital radiographs. Fortunately, the user of these systems does not need to understand image processing in detail, because the manufacturers provide good starting values. Because radiologists may have different preferences in image appearance, it is helpful to know that many aspects of image appearance can be changed by image processing, and a new preferred setting can be loaded into the computer and saved so that it can become the new standard processing method.Image processing allows one to change the overall optical density of an image and to change its contrast. Spatial frequency processing allows an image to be sharpened, improving its appearance. It also allows noise to be blurred so that it is less visible. Care is necessary to avoid the introduction of artifacts or the hiding of mediastinal tubes. 相似文献
44.
45.
46.
目的 :探讨次侧切开内括约肌治疗肛裂术前、术后肛门直肌压力的变化。方法 :采用自行设计的次侧方内括约肌切开加双缘结扎术治疗 期肛裂 6 0例 ,测定手术前后肛门直肠压力 ,并与 6 0例正常人肛压比较 ,评价新术式治疗 期肛裂的临床疗效及其对肛门功能的影响。结果 :显示术后患者肛管静息压显著降低 ,与术前比较有显著性差异 (P <0 .0 1) ,与正常人比较无显著性差异 (P>0 .0 5 ) ;肛管最大收缩压与术前及正常人比较无显著性差异 (P>0 .0 5 )。结论 :次侧方内括约肌切开加双缘结扎术能有效地解除内括约肌痉挛 ,从根本上消除高肛压 ,从而彻底治愈肛裂 ,而且不影响肛门功能。 相似文献
47.
Reto Treier Andreas Steingoetter Michael Fried Werner Schwizer Peter Boesiger 《Magnetic resonance in medicine》2007,57(3):568-576
Fast T(1) mapping techniques are a valuable means of quantitatively assessing the distribution and dynamics of intravenously or orally applied paramagnetic contrast agents (CAs) by noninvasive imaging. In this study a fast T(1) mapping technique based on the variable flip angle (VFA) approach was optimized for accurate T(1) quantification in abdominal contrast-enhanced (CE) MRI. Optimization methods were developed to maximize the signal-to-noise ratio (SNR) and ensure effective RF and gradient spoiling, as well as a steady state, for a defined T(1) range of 100-800 ms and a limited acquisition time. We corrected B(1) field inhomogeneities by performing an additional measurement using an optimized fast B(1) mapping technique. High-precision in vitro and abdominal in vivo T(1) maps were successfully generated at a voxel size of 2.8 x 2.8 x 15 mm(3) and a temporal resolution of 2.3 s per T(1) map on 1.5T and 3T MRI systems. The application of the proposed fast T(1) mapping technique in abdominal CE-MRI enables noninvasive quantification of abdominal tissue perfusion and vascular permeability, and offers the possibility of quantitatively assessing dilution, distribution, and mixing processes of labeled solutions or drugs in the gastrointestinal tract. 相似文献
48.
MRI测量颈胸角在选择颈胸段脊柱手术入路中的临床应用 总被引:11,自引:8,他引:3
目的 :探讨在颈胸段脊柱术前应结合患者的颈胸段MRI的个体特征和疾病情况 ,选择手术创伤最小的手术入路。方法 :共 76例患者 ,其中 2 6例为颈胸段脊柱损伤 ,35例为颈胸段脊柱肿瘤 ,脊髓型颈椎病 12例 ,以及 3例颈胸段椎板减压术后后凸畸形。男 4 7例 ,女 2 9例。平均年龄 4 5 5岁 ,年龄范围 19~ 6 5岁。同时抽取 95套颈胸段MRI片。作胸骨上切迹向后水平延长线和胸骨上切迹向后上方至C7T1椎间盘前缘中点的连线 ,测量两线之夹角 ,称为颈胸角 (cervicothoracicangle ,CTA)。结果 :CTA平均为 4 7 6 4°(范围 2 5°~ 73°)。大于此平均角度且病灶在胸骨切迹水平线以上时可考虑低位下颈椎入路 ,5 0例 ;CTA较小 ,且病灶范围广 ,或尚累及T3 、T4,可以考虑经胸骨柄入路 ,13例 ;病灶范围广泛 ,经全胸骨入路 3例 ;Ⅰ期或Ⅱ期前后联合入路 5例 ;经右侧肩胛下后外侧胸腔入路 5例。结论 :颈胸段脊柱手术应尽量选择低位下颈椎入路等创伤较小的入路 ,其次考虑经胸骨柄入路。长节段脊柱受累的患者才考虑经右侧肩胛下后外侧胸腔或经全胸骨等创伤较大的入路。术前可以结合患者的病灶累及范围和颈胸手术角等MRI影像学表现 ,从而利于选择最合适的手术入路 ,减少手术风险、手术创伤和并发症 ,利于患者早日康复 相似文献
49.
50.
Among British-qualified doctors of 1974 and 1977, about 80% held postgraduate qualifications of some kind. The commonest qualifications were DRCOG, MRCP and MRCOG. There were considerable differences between medical schools in the numbers of qualifiers taking various examinations. Apart from the MRC Psych, DRCOG and Family Planning Certificate, qualifications were more commonly held by men than women. Tables show the type of work being done 9-13 years after leaving medical school by holders of various postgraduate qualifications; e.g. 60% of MRCP holders were working in medicine or a medical specialty and 84% of FRCS holders in general surgery or a surgical specialty. Discussion deals with the plurality, specificity, variability, perceived necessity, sufficiency, international utility and career significance of British postgraduate qualifications. 相似文献