全文获取类型
收费全文 | 1715篇 |
免费 | 128篇 |
国内免费 | 3篇 |
专业分类
耳鼻咽喉 | 1篇 |
儿科学 | 77篇 |
妇产科学 | 36篇 |
基础医学 | 189篇 |
口腔科学 | 36篇 |
临床医学 | 212篇 |
内科学 | 437篇 |
皮肤病学 | 31篇 |
神经病学 | 89篇 |
特种医学 | 297篇 |
外科学 | 112篇 |
综合类 | 22篇 |
预防医学 | 92篇 |
眼科学 | 18篇 |
药学 | 91篇 |
1篇 | |
中国医学 | 3篇 |
肿瘤学 | 102篇 |
出版年
2019年 | 14篇 |
2018年 | 25篇 |
2017年 | 20篇 |
2016年 | 11篇 |
2015年 | 23篇 |
2014年 | 23篇 |
2013年 | 35篇 |
2012年 | 41篇 |
2011年 | 28篇 |
2010年 | 53篇 |
2009年 | 56篇 |
2008年 | 65篇 |
2007年 | 56篇 |
2006年 | 50篇 |
2005年 | 51篇 |
2004年 | 48篇 |
2003年 | 32篇 |
2002年 | 31篇 |
2001年 | 30篇 |
2000年 | 27篇 |
1999年 | 31篇 |
1998年 | 59篇 |
1997年 | 73篇 |
1996年 | 65篇 |
1995年 | 50篇 |
1994年 | 59篇 |
1993年 | 56篇 |
1992年 | 31篇 |
1991年 | 33篇 |
1990年 | 32篇 |
1989年 | 55篇 |
1988年 | 54篇 |
1987年 | 48篇 |
1986年 | 42篇 |
1985年 | 39篇 |
1984年 | 21篇 |
1983年 | 30篇 |
1982年 | 23篇 |
1981年 | 27篇 |
1980年 | 30篇 |
1979年 | 22篇 |
1978年 | 21篇 |
1977年 | 30篇 |
1976年 | 22篇 |
1975年 | 25篇 |
1974年 | 18篇 |
1973年 | 23篇 |
1972年 | 15篇 |
1971年 | 17篇 |
1968年 | 10篇 |
排序方式: 共有1846条查询结果,搜索用时 15 毫秒
1.
Stephan E. Maier Harvey E. Cline Ferenc A. Jolesz 《Magnetic resonance in medicine》1995,34(5):706-712
Three dimensional (3D) phase contrast angiograms contain velocity data, which is discarded after the reconstruction of the projections. In extension to earlier work on velocity quantification with ungated 2D phase data, this paper shows that a useful estimate of the average velocity and flow rate can be extracted from ungated 3D phase contrast angiograms. Simulations and experiments in a phantom and in vivo were performed. For pulsatile flow and strong spin saturation, an over-estimation of the flow rate at the net in-flow end of the imaging volume and underestimation at the net out-flow end was observed. Imaging at lower RF tip angles yielded flow rates close to the correct value within the entire imaging volume. In contrast to ungated 2D experiments, the flow rates determined by repeated 3D experiments showed no variation. 相似文献
2.
Oblique muscle palsies fixating with the paretic eye 总被引:1,自引:0,他引:1
Palsy of the superior oblique muscle is one of the most commonly occurring entities in strabismus; the clinical characteristics are easily recognizable. Isolated inferior oblique muscle palsy, although anatomically enigmatical, is also known to ophthalmologists. When a patient with an oblique muscle palsy chooses to fixate with the paretic eye, characteristic patterns of motility may be obscured. Patients with superior oblique muscle palsy or isolated inferior oblique muscle palsy who habitually fixate with the paretic eye, may present with limited elevation or depression respectively. In each case, limited motility exists secondary to decreased innervational input to the contralateral antagonist of the paretic muscle, or to a mechanical restriction caused by prolonged contracture of the yoke of the paretic muscle. Inhibitional palsy of the contralateral antagonists and the fallen and rising eye syndromes may present diagnostic dilemmas unless the underlying oblique muscle palsy is recognized. Proper diagnosis may be obtained with three clinical tests; the 3-step test, the comparison of ductions to versions, and forced ductions. 相似文献
3.
Preliminary evidence for a role of apolipoprotein E alleles in identifying haemodialysis patients at high vascular risk 总被引:1,自引:0,他引:1
Olmer M; Renucci JE; Planells R; Bouchouareb D; Purgus R 《Nephrology, dialysis, transplantation》1997,12(4):691-693
Conventional risk factors have very low predictive power in identifying
haemodialysis patients at high risk of vascular accidents. A role for
apolipoprotein E isotypes was looked for in a small, but rigorously
defined, cohort of longterm haemodialysis patients. In individuals with
high vascular risk, as identified by higher common carotid intima/media
thickness, we found an excess of apolipoprotein E4 alleles. This
preliminary result requires confirmation in large patient cohorts.
相似文献
4.
5.
6.
M. Bar-Eli H. D. Stang K. E. Mercola M. J. Cline 《Somatic Cell and Molecular Genetics》1983,9(1):55-67
DNA-mediated gene transfer was used to introduce DNA from a methotrexate-resistant mouse fibroblast cell line into mouse bone marrow cells. This cell line contained a methotrexate-resistant dihydrofolate reductase, active at 10?4 M methotrexate, which was electrophoretically separable from the wild-type mouse enzyme. Transformed hematopoietic cells were returned to irradiated mice and selected in vivo by methotrexate administration. Some recipients of transformed marrow cells expressed the electrophoretically distinct, methotrexate-resistant dihydrofolate reductase in hematopoietic cells. These observations suggest that successful transformation of marrow stem cells to methotrexate resistance is accomplished by insertion of a dihydrofolate reductase gene coding for a mutant enzyme that is highly resistant to methotrexate. 相似文献
7.
8.
9.
Hodgkin disease: CT of the thymus 总被引:2,自引:0,他引:2
The computed tomography (CT) scans in two groups of patients with Hodgkin disease were reviewed to determine the frequency of thymic enlargement. In 50 CT scans from 50 patients with evidence of thoracic disease on CT scans who were examined for primary staging, the thymus was enlarged in 15 of 50 (30%). Fifty CT scans were obtained from 44 patients at the time of 50 separate episodes of known or suspected relapse. Relapse occurred in the mediastinum in 12 episodes, lung parenchyma in five, and both sites in one. Thymic enlargement thought to be due to involvement by disease was present in seven of 18 (38%). Mediastinal disease was associated with thymic enlargement in all but one patient in whom a thymic cyst developed after radiation therapy. Differentiation of thymic enlargement from enlarged superior mediastinal lymph nodes was easily made in all but two patients. Thymic enlargement in the absence of lymph node enlargement may indicate a different disease, since isolated Hodgkin disease of the thymus is uncommon. Primary thymic tumor should be considered initially, whereas after treatment, rebound hyperplasia of the thymus may be the cause of enlargement. 相似文献
10.
Solitary bronchioloalveolar carcinoma: CT criteria 总被引:14,自引:0,他引:14
Kuhlman JE; Fishman EK; Kuhajda FP; Meziane MM; Khouri NF; Zerhouni EA; Siegelman SS 《Radiology》1988,167(2):379-382
The computed tomographic (CT) scans of 30 patients with solitary bronchioloalveolar carcinoma were reviewed. Common features at CT included the peripheral or subpleural location of a pulmonary mass (25 cases), pseudocavitation (18 cases), heterogeneous attenuation (17 cases), irregular margins forming a star pattern (22 cases), and pleural tags (21 cases). Using these CT criteria, four independent observers attempted to identify cases of bronchioloalveolar carcinoma from a larger sample of lung cancers and benign lesions by categorizing a series of test cases into four probability categories. Although the bronchioloalveolar carcinomas were correctly ranked in the two highest probability categories 75% of the time (in 45 of 60 cases), there was considerable overlap with other lung lesions, particularly with adenocarcinoma and large cell undifferentiated carcinoma. However, even though the typical features of bronchioloalveolar carcinoma are not invariable or highly specific, they are characteristic enough to suggest the diagnosis. 相似文献