全文获取类型
收费全文 | 946篇 |
免费 | 172篇 |
国内免费 | 17篇 |
专业分类
耳鼻咽喉 | 13篇 |
儿科学 | 47篇 |
妇产科学 | 9篇 |
基础医学 | 64篇 |
口腔科学 | 10篇 |
临床医学 | 154篇 |
内科学 | 244篇 |
皮肤病学 | 29篇 |
神经病学 | 71篇 |
特种医学 | 95篇 |
外科学 | 177篇 |
综合类 | 48篇 |
现状与发展 | 20篇 |
预防医学 | 59篇 |
眼科学 | 25篇 |
药学 | 20篇 |
中国医学 | 2篇 |
肿瘤学 | 48篇 |
出版年
2024年 | 7篇 |
2023年 | 42篇 |
2021年 | 17篇 |
2020年 | 22篇 |
2019年 | 11篇 |
2018年 | 50篇 |
2017年 | 45篇 |
2016年 | 31篇 |
2015年 | 44篇 |
2014年 | 41篇 |
2013年 | 57篇 |
2012年 | 23篇 |
2011年 | 30篇 |
2010年 | 46篇 |
2009年 | 66篇 |
2008年 | 34篇 |
2007年 | 25篇 |
2006年 | 29篇 |
2005年 | 20篇 |
2004年 | 15篇 |
2003年 | 18篇 |
2002年 | 16篇 |
2001年 | 20篇 |
2000年 | 13篇 |
1999年 | 23篇 |
1998年 | 30篇 |
1997年 | 36篇 |
1996年 | 46篇 |
1995年 | 30篇 |
1994年 | 19篇 |
1993年 | 22篇 |
1992年 | 8篇 |
1991年 | 10篇 |
1990年 | 15篇 |
1989年 | 13篇 |
1988年 | 15篇 |
1987年 | 16篇 |
1986年 | 12篇 |
1985年 | 12篇 |
1984年 | 6篇 |
1983年 | 6篇 |
1982年 | 8篇 |
1980年 | 5篇 |
1978年 | 15篇 |
1977年 | 8篇 |
1976年 | 9篇 |
1975年 | 5篇 |
1971年 | 4篇 |
1964年 | 5篇 |
1963年 | 4篇 |
排序方式: 共有1135条查询结果,搜索用时 15 毫秒
1.
Paul Wexberg MD BM Richard Pacher MD Suzanne Rdler MD Katharina Kiss MD Gilbert Beran MD Michael Grimm MD Gerald Maurer MD Dietmar Glogar MD FESC 《The Journal of heart and lung transplantation》2002,21(12):583-1263
BACKGROUND: Endothelin, a peptide with strong vasoconstrictive and mitogenic properties, has been found to increase after cardiac transplantation. We therefore assessed the association between its precursor peptide, big endothelin-1, and intimal hyperplasia and coronary flow reserve after heart transplantation. METHODS: Thirty-five patients without hemodynamically significant coronary artery disease after heart transplantation were investigated: Average peak flow velocity in the left anterior descending artery (LAD) was assessed by intracoronary Doppler at baseline as well as after injection of adenosine; coronary flow reserve was calculated as a ratio of both and was corrected for patient age and baseline average peak flow velocity. Lumen, intima + media and total vessel area were measured by intracoronary ultrasound. The plasma concentration of big endothelin-1 in venous blood was determined by radioimmunoassay. RESULTS: Patients with elevated big endothelin-1 levels (>2 fmol/ml) tended to have a decreased corrected coronary flow reserve (2.60 +/- 0.9 vs 3.21 +/- 1.0, p = 0.078). They also had a significantly larger intima + media area (5.82 +/- 2.9 vs 2.37 +/- 2.9 mm(2), p = 0.004) and total vessel area (18.36 +/- 5.8 vs 12.81 +/- 4.8 mm(2), p = 0.012) than those with normal plasma concentrations. CONCLUSIONS: Our study suggests an association between elevated big endothelin-1 plasma levels and the development of intimal hyperplasia and reduction of coronary flow reserve after cardiac transplantation. 相似文献
2.
3.
Beat M. Jucker Maria L. Barnard Robert G. Shulman 《Alcoholism, clinical and experimental research》1994,18(6):1377-1385
Weight gain efficiency differences previously reported between alcohol-fed rats and their controls were investigated. Additionally, the futile cycling of ethanol proposed to explain such differences was studied by NMR spectroscopy. Male Sprague-Dawley rats were fed a nutritionally adequate diet containing 36% of the calories as alcohol, and their paired controls were fed an isocaloric diet for 1 f weeks to establish conditions of chronic alcohol feeding. Normalized metabolic efficiencies varied significantly during the initial 2-week period (6.86 ± 0.51 vs. 2.83 ± 0.18 g/kcal × 10−2 ) for control and alcohol-fed groups, respectively, and to a lesser extent over the entire feeding period (6.41 ± 0.78 vs. 4.60 ± 0.27 g/kcal × 10−2 ) for control and alcohol-fed groups, respectively. Alcohol-induced weight gain inefficiency in metabolism has previously been studied and explained by a variety of different biochemical and physiological mechanisms. One possible pathway of energy wastage may occur due to ethanol futile cycling from ethanol to acetaldehyde through the microsomal ethanol oxidation system pathway, and simultaneously from acetaldehyde to ethanol via the ADH pathway. This futile cycle represents a net loss of 6 ATP/cycle, corresponding to the loss of two reducing equivalents (NADH and NADPH). 1H NMR spectroscopy was used to test for this cycling in blood extracts after administration of 1,1-2 H2 ethanol. No futile cycling was detected either during the initial 2 weeks of feeding or after the entire feeding period. 相似文献
4.
L. C. Walker C. A. Parker W. J. Lipinski M. J. Callahan R. T. Carroll S. E. Gandy J. D. Smith M. Jucker C. L. Bisgaier 《The American journal of pathology》1997,151(5):1371-1377
To assess the influence of age and diet on cerebral pathology in mice lacking apolipoprotein E (apoE), four male apoE knockout mice (epsilon -/-), and five male wild-type (epsilon +/+) littermate controls were placed on a high-fat/high-cholesterol diet for 7 weeks beginning at 17 months of age. All four aged knockout mice developed xanthomatous lesions in the brain consisting mostly of crystalline cholesterol clefts, lipid globules, and foam cells. Smaller xanthomas were confined mainly to the choroid plexus and ventral fornix in the roof of the third ventricle, occasionally extending subpially along the choroidal fissure and into the adjacent parenchyma. More advanced xanthomas disrupted adjoining neural tissue in the fornix, hippocampus, and dorsal diencephalon; in one case, over 60% of one telencephalic hemisphere, including nearly the entire neocortex, was obliterated by the lesion. No xanthomas were observed in aged wild-type controls fed the high-fat/high-cholesterol diet. Brains from 42 additional animals, fed only conventional chow, were examined; 3 of 15 aged (15- to 23-month-old) apoE knockout mice developed small choroidal xanthomas. In contrast, no lesions were observed in five young (2- to 4-month-old) apoE knockout mice or in any wild-type controls between the ages of 2 and 23 months. Our findings indicate that disorders of lipid metabolism can induce significant pathological changes in the central nervous system of aged apoE knockout mice, particularly those on a high-fat/high-cholesterol diet. It may be fruitful to seek potential interactions between genetic factors and diet in modulating the risk of Alzheimer's disease and other neurodegenerative disorders in aged humans. 相似文献
5.
6.
The computerized database system described was initially developed in 1986 to facilitate analysis of retrospective head and neck cancer data from the Royal Adelaide Hospital Department of Otolaryngology. This has now been expanded to become an on-going patient information management system. It is based on the dBase-III-Plus database package and is implemented on an IBM XT compatible computer. The system was designed to be used by staff without specialist computer skills and is therefore largely “menu-driven.” The main functions include patient record creation, update, and retrieval, and the production of reports including graphical presentations. There is also a powerful but easy to use query facility. The system has already provided much useful epidemiological material but is now beginning to fulfill an even more important role in patient follow-up and in assisting evaluation of alternative treatment protocols. 相似文献
7.
3D-Reconstruction of microglia and amyloid in APP23 transgenic mice: no evidence of intracellular amyloid 总被引:6,自引:0,他引:6
Microglia cells are closely associated with compact amyloid plaques in Alzheimer's disease (AD) brains. Although activated microglia seem to play a central role in the pathogenesis of AD, mechanisms of microglial activation by beta-amyloid as well as the nature of interaction between amyloid and microglia remain poorly understood. We previously reported a close morphological association between activated microglia and congophilic amyloid plaques in the brains of APP23 transgenic mice at both the light and electron microscopic levels [25]. In the present study, we have further examined the structural relationship between microglia and amyloid deposits by using postembedding immunogold labeling, serial ultrathin sectioning, and 3-dimensional reconstruction. Although bundles of immunogold-labeled amyloid fibrils were completely engulfed by microglial cytoplasm on single sections, serial ultrathin sectioning and three-dimensional reconstruction revealed that these amyloid fibrils are connected to extracellular amyloid deposits. These data demonstrate that extracellular amyloid fibrils form a myriad of finger-like channels with the widely branched microglial cytoplasm. We conclude that in APP23 mice a role of microglia in amyloid phagocytosis and intracellular production of amyloid is unlikely. 相似文献
8.
Mahadevaiah SK; Odorisio T; Elliott DJ; Rattigan A; Szot M; Laval SH; Washburn LL; McCarrey JR; Cattanach BM; Lovell-Badge R; Burgoyne PS 《Human molecular genetics》1998,7(4):715-727
An RNA-binding motif (RBM) gene family has been identified on the human Y
chromosome that maps to the same deletion interval as the 'azoospermia
factor' (AZF). We have identified the homologous gene family (Rbm) on the
mouse Y with a view to investigating the proposal that this gene family
plays a role in spermatogenesis. At least 25 and probably >50 copies of
Rbm are present on the mouse Y chromosome short arm located between Sry and
the centromere. As in the human, a role in spermatogenesis is indicated by
a germ cell-specific pattern of expression in the testis, but there are
distinct differences in the pattern of expression between the two species.
Mice carrying the deletion Yd1, that maps to the proximal Y short arm, are
female due to a position effect resulting in non-expression of Sry ;
sex-reversing such mice with an Sry transgene produces males with a high
incidence of abnormal sperm, making this the third deletion interval on the
mouse Y that affects some aspect of spermatogenesis. Most of the copies of
Rbm map to this deletion interval, and the Yd1males have markedly reduced
Rbm expression, suggesting that RBM deficiency may be responsible for, or
contribute to, the abnormal sperm development. In man, deletion of the
functional copies of RBM is associated with meiotic arrest rather than
sperm anomalies; however, the different effects of deletion are consistent
with the differences in expression between the two species.
相似文献
9.