全文获取类型
收费全文 | 301078篇 |
免费 | 11803篇 |
国内免费 | 8413篇 |
专业分类
耳鼻咽喉 | 2176篇 |
儿科学 | 8161篇 |
妇产科学 | 5291篇 |
基础医学 | 31049篇 |
口腔科学 | 3620篇 |
临床医学 | 28966篇 |
内科学 | 51099篇 |
皮肤病学 | 2104篇 |
神经病学 | 23077篇 |
特种医学 | 13250篇 |
外国民族医学 | 70篇 |
外科学 | 41827篇 |
综合类 | 21959篇 |
现状与发展 | 24篇 |
一般理论 | 5篇 |
预防医学 | 25964篇 |
眼科学 | 6352篇 |
药学 | 22253篇 |
115篇 | |
中国医学 | 6945篇 |
肿瘤学 | 26987篇 |
出版年
2024年 | 351篇 |
2023年 | 1839篇 |
2022年 | 4719篇 |
2021年 | 5950篇 |
2020年 | 4303篇 |
2019年 | 4121篇 |
2018年 | 25658篇 |
2017年 | 20800篇 |
2016年 | 22687篇 |
2015年 | 6173篇 |
2014年 | 7438篇 |
2013年 | 7010篇 |
2012年 | 16026篇 |
2011年 | 30772篇 |
2010年 | 24787篇 |
2009年 | 16371篇 |
2008年 | 26013篇 |
2007年 | 28175篇 |
2006年 | 7205篇 |
2005年 | 8745篇 |
2004年 | 7819篇 |
2003年 | 8495篇 |
2002年 | 5994篇 |
2001年 | 3498篇 |
2000年 | 3729篇 |
1999年 | 3598篇 |
1998年 | 2433篇 |
1997年 | 2363篇 |
1996年 | 1647篇 |
1995年 | 1553篇 |
1994年 | 1362篇 |
1993年 | 876篇 |
1992年 | 1261篇 |
1991年 | 1156篇 |
1990年 | 1051篇 |
1989年 | 896篇 |
1988年 | 762篇 |
1987年 | 705篇 |
1986年 | 529篇 |
1985年 | 491篇 |
1984年 | 267篇 |
1983年 | 198篇 |
1982年 | 142篇 |
1981年 | 116篇 |
1980年 | 115篇 |
1979年 | 122篇 |
1978年 | 67篇 |
1975年 | 60篇 |
1974年 | 84篇 |
1938年 | 61篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
21.
Hitoshi Ogino Nongchana Klangsuk Wu Jin Christopher T. Bowles Magdi H. Yacoub 《Artificial organs》1995,19(6):525-534
Abstract: The dependence of transient pressure characteristics of a ventricular assist device (VAD) on the compliance of its housing and cannulas was investigated in a mock circulation. The peak rate of change of pressure ( dP/dt max ) values was greater in the cannulas than other compartments and was associated with valve closure-induced pressure oscillations. When cannula compliance was increased from 0.0057 to 0.0129 cm3 /mm Hg, these values decreased by ˜20%, and outflow cannula pressure oscillation frequency decreased from 17.5 Hz by 35%. This trend was also apparent in the inflow. A VAD housing compliance increase from 0.0162 to 0.0483 cm3 /mm Hg caused a dP/dt max decrease of 30% in both the blood chamber and the outflow cannula. The effect of this change on the inflow was weaker implying that housing absorbs the energy associated with outflow deceleration more effectively than the inflow. These findings suggest that increasing VAD housing and cannulas compliance can improve hydrodynamic performance. 相似文献
22.
医源性胆管狭窄X线表现 总被引:1,自引:0,他引:1
本文报道了13例医源性胆管狭窄,分析其影像表现。特点为:环形狭窄;线样狭窄,包括规则的和不规则的线样狭窄;闭塞性狭窄;胆管闭塞和胆管中断分离。ERCT和PCT对狭窄的形态,位置及长度显示优于CT和US。 相似文献
23.
24.
功能性消化不良与幽门螺杆菌关系探讨 总被引:6,自引:0,他引:6
功能性消化不良是一种人群中发病率很高的消化系统症状群,其发病机理未完全阐明,本文通过对2742例各类型功能性消化不良患者的胃粘膜的幽门螺杆菌感染情况作分析,发现动力障碍型HP阳性率65.3%,溃疡型HP阳性率74%,胃食管反流型HP阳性率24%,特发型HP阳性率21.4%,前两型与后两型的阳性率差异有显著性(P〈0.05),而前两型之间阳性率差异无显著性(P〉0.05),说明HP与动力障碍型和溃疡 相似文献
25.
Summary This study explores the effects of a calcium-deficient diet on patterns of bone remodeling, and examines regional differences
in the amount of bone lost. Skeletally mature female rabbits (n=6) were fed a calcium-deficient diet (0.10% Ca2+ and 0.50% P) for 14 weeks. A separate group of rabbits (n=4) were fed a maintenance diet (1.2% Ca2+ and 0.45% P). Bone mineral content, serum calcium, and serum phosphorus were measured each week during the experimental period.
Following sacrifice, the L3 vetebra, femoral head, proximal tibial metaphysis, and tibial midshaft were analyzed histomorphometrically. Rabbits had 20%
less vertebral bone after only 14 weeks of a calcium-deficient diet. As in human postmenopausal osteoporosis, bone loss in
calcium-deficient rabbits occurs in the trabecular bone of the lumbar spine before that in the trabecular bone of the lower
extremity. Calcium-deficient diets alone do not lead to increased osteoid volume or thickness. Because bone loss is relatively
rapid and because the pattern of loss is similar in some respects to that found in humans, adult rabbits may provide an attractive
model of calcium deficiency osteoporosis in a skeletally mature mammal in which remodeling is predominant over modeling. 相似文献
26.
Regulatory properties of brain glutamate decarboxylase (GAD): the apoenzyme of GAD is present principally as the smaller of two molecular forms of GAD in brain 总被引:10,自引:0,他引:10
The apoenzyme of glutamate decarboxylase [enzyme without bound cofactor, pyridoxal 5'-phosphate (pyridoxal-P)] serves as a reservoir of inactive glutamate decarboxylase (GAD) that can be activated when additional GABA synthesis is required. We have investigated which of two molecular forms of GAD is present as apoenzyme in synaptosomes and in cortex, caudate nucleus, hippocampus, and cerebellum of rat brain. Endogenous glutamate apodecarboxylase (apoGAD) was labeled by incubating extracts of synaptosomes or punches of each region with 32P-pyridoxal-P, followed by reduction with NaBH4, to link covalently the 32P-pyridoxal-P to GAD. Proteins were separated by SDS-PAGE. Punches from all four brain regions and forebrain synaptosomes contained two forms of GAD with apparent Mrs of 63 and 65 kDa as identified by immunoblotting with four antiGAD sera. Punches and synaptosomes contained a major 32P-pyridoxal-P-labeled band with an apparent Mr of 63 kDa that was stained on immunoblots by the antiGAD serum 1440 and the monoclonal antibody GAD-6, and a minor labeled band at 65 kDa that was stained by the 1440, 6799, and K2 antisera. Synaptosomes contained remarkably few other strongly labeled proteins, but punches contained several other labeled bands. Three additional lines of evidence indicate that the labeled 63-kDa protein is apoGAD: (1) it was purified by immunoaffinity chromatography with the GAD-1 monoclonal antibody; (2) it yielded one major labeled peptide when digested with chymotrypsin, and that peptide appeared identical in peptide-mapping experiments to the labeled active-site peptide isolated from chromatographically prepared rat brain GAD; and (3) its labeling was selectively blocked by 4-deoxypyridoxine 5'-phosphate, a competitive inhibitor of the binding of pyridoxal-P to GAD.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
27.
28.
29.
The efficacy of radiology in evaluating dysphagia was studied in 86 patients by comparison to endoscopic findings. In the 66 patients with endoscopic abnormalities radiology was correct in 54, for a sensitivity of 82%. Sensitivity of radiology improved to 95% if mild esophagitis was excluded. In the 20 patients with normal endoscopy, radiology was normal in 18 (90%). Thus radiology proved to be a reliable means of evaluating the esophagus in patients with dysphagia. 相似文献
30.
Paul Hochstein Ulrich Glatzel Thomas Schmickal Andreas Wentzensen 《Trauma und Berufskrankheit》2002,4(2):s110-s114
The treatment of deep cartilage defects in load-bearing joints is a problem that still has no satisfactory solution. Full-thickness defects of the articular cartilage rarely heal spontaneously, usually leaving damage that can lead to early arthrosis. Techniques currently available for the treatment of chondral defects include abrasion, drilling, micro-fracturing, transplantation of tissue autografts and allografts, and cell transplantation. Osteochondral autograft transplantation is currently the only surgical cartilage repair technique known to lead to the formation of genuine hyaline articular cartilage and its retention at least in the medium term. The Draenert method, in which a water-cooled diamond bone-cutting system is used, is an effective procedure for resurfacing the joints affected by localised cartilaginous defects, even when there is also severe bone loss. Donor-side morbidity can be kept to a minimum by filling the defect caused by harvesting with a press-fit cylinder of cancellous bone covered with periosteum for protection. 相似文献