全文获取类型
收费全文 | 26753篇 |
免费 | 1919篇 |
国内免费 | 148篇 |
专业分类
耳鼻咽喉 | 246篇 |
儿科学 | 928篇 |
妇产科学 | 718篇 |
基础医学 | 3675篇 |
口腔科学 | 492篇 |
临床医学 | 2876篇 |
内科学 | 5452篇 |
皮肤病学 | 565篇 |
神经病学 | 2835篇 |
特种医学 | 618篇 |
外科学 | 2583篇 |
综合类 | 193篇 |
一般理论 | 42篇 |
预防医学 | 3348篇 |
眼科学 | 344篇 |
药学 | 1656篇 |
1篇 | |
中国医学 | 41篇 |
肿瘤学 | 2207篇 |
出版年
2023年 | 393篇 |
2022年 | 707篇 |
2021年 | 1244篇 |
2020年 | 783篇 |
2019年 | 1050篇 |
2018年 | 1127篇 |
2017年 | 859篇 |
2016年 | 940篇 |
2015年 | 965篇 |
2014年 | 1262篇 |
2013年 | 1572篇 |
2012年 | 2264篇 |
2011年 | 2272篇 |
2010年 | 1174篇 |
2009年 | 990篇 |
2008年 | 1511篇 |
2007年 | 1417篇 |
2006年 | 1327篇 |
2005年 | 1184篇 |
2004年 | 1042篇 |
2003年 | 896篇 |
2002年 | 774篇 |
2001年 | 223篇 |
2000年 | 215篇 |
1999年 | 206篇 |
1998年 | 151篇 |
1997年 | 129篇 |
1996年 | 116篇 |
1995年 | 119篇 |
1994年 | 82篇 |
1993年 | 86篇 |
1992年 | 128篇 |
1991年 | 115篇 |
1990年 | 121篇 |
1989年 | 115篇 |
1988年 | 120篇 |
1987年 | 93篇 |
1986年 | 87篇 |
1985年 | 91篇 |
1984年 | 76篇 |
1983年 | 62篇 |
1982年 | 61篇 |
1981年 | 64篇 |
1978年 | 50篇 |
1977年 | 45篇 |
1976年 | 41篇 |
1975年 | 47篇 |
1974年 | 47篇 |
1973年 | 43篇 |
1972年 | 43篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
Sara Boulaïch Annie Daszuta Michel Geffard Olivier Bosler 《Experimental brain research. Experimentelle Hirnforschung. Expérimentation cérébrale》1994,101(3):353-364
We have previously reported that a cell suspension from the rostral part of the embryonic raphe grafted to the basal hypothalamus of 5,7-dihydroxytryptamine-denervated rats produced incomplete serotonin (5-HT) re-innervation of the suprachiasmatic nucleus (SCN) as opposed to hyper-innervation of the supraoptic nucleus (SON). We took advantage of this experimental model to investigate whether the graft-derived, 5-HT fibres retained normal ultrastructural features, and, particularly, a normal density of synaptic junctions, irrespective of the extent of target re-innervation. The intrinsic features of immunostained, graft-derived 5-HT axonal varicosities in both the SCN (ventral portion) and the SON were essentially similar to those exhibited by the respective endogenous innervation. Analysis of well-preserved varicosities in uninterrupted series of thin sections allowed us to evaluate directly the proportions of junctional to non-junctional 5-HT varicosities in both regions. Synaptic incidences were also remarkably conserved after grafting (45.5% in the SCN versus 38.5% in the SON; 48% and 38% in normal rats, respectively). Synapses were primarily reestablished on dendritic shafts, which also were identified as the major post-synaptic targets of the normal 5-HT innervations. We noted, however, a tendency toward increased numbers of symmetrical versus asymmetrical synapses in both the SCN and SON of grafted rats. Thus, irrespective of whether hypo-or hyper-innervation patterns developed post-grafting, the transplanted 5-HT neurons essentially retained normal ultrastructural features in their target territories, with a normal incidence of synaptic junctions. The data provide further support to the hypothesis that the innervation territory is the major determinant of the frequency with which ingrowing 5-HT fibres make synaptic junctions. 相似文献
82.
83.
84.
Mechanical properties of dilated human ascending aorta 总被引:3,自引:0,他引:3
Okamoto RJ Wagenseil JE DeLong WR Peterson SJ Kouchoukos NT Sundt TM 《Annals of biomedical engineering》2002,30(5):624-635
Dilation of the ascending aorta, associated with Marfan Syndrome, bicuspid aortic valve, or advanced age, may lead to aortic dissection and rupture. Mathematical models can be used to assess the relative importance of increased wall stresses and decreased strength in these mechanical failures. To obtain needed inputs for such models, mechanical properties of dilated human ascending aorta were measured in vitro. Specimens for opening angle, biaxial elastic, and uniaxial circumferential strength tests were cut from excised tissue obtained from 54 patients (age 18–81 years) undergoing elective aortic graft replacement surgery. Opening angle was significantly greater in patients older than 50 years (262°±76°, n=21) compared to younger patients (202°±70°, n=13 All biaxial elastic specimens n=40 exhibited nonlinear stress-strain behavior. Rapid increases in circumferential and axial stresses occurred at lower strains in the older patient group than in the younger. Mean strength was significantly lower in older patients (1.35±0.37 MPa, n=14) than younger (2.04 ± 0.46 MPa, n=11, age <50 years). These changes in mechanical properties suggest that age may influence the risk of aortic dissection or rupture of dilated ascending aorta. © 2002 Biomedical Engineering Society.
PAC2002: 8719Rr, 8719Hh 相似文献
85.
Oral administration of muscle derived small molecules inhibits tumor spread while promoting normal cell growth in mice 总被引:5,自引:0,他引:5
Bar-Yehuda S Farbstein T Barer F Ohana G Fishman P 《Clinical & experimental metastasis》1999,17(6):531-535
Tumor metastases are extremely rare in striated muscles. This is surprising given the fact that this tissue constitutes 60%
of body weight. The present study focuses on small molecules produced and secreted by muscle cells which possess anti-cancer
activity in vivo. Recently we have shown that a low molecular weight fraction (<1000 Dalton) of skeletal muscle cell conditioned medium (muscle
factor-MF), markedly inhibits the proliferation of carcinoma, sarcoma or melanoma cell lines in vitro. The MF exerts a cytostatic effect on tumor cell growth and arrests the cells in the G0/G1 of the cell cycle. However, normal
cell proliferation, such as bone marrow and fibroblasts, was stimulated following incubation with MF. In this study, the effect
of orally administered MF on melanoma and sarcoma growth was examined in mice. The administration of MF to mice inoculated
intravenously with melanoma (B16–F10) or sarcoma (MCA-105) cells, resulted in a statistically significant inhibition of metastatic
lung foci. In a different model, melanoma was induced in the foot pad and after development of a local lesion, the leg was
amputated. A prolonged survival time was observed in the MF treated groups. Since the MF stimulated bone marrow cell proliferation
in vitro, we decided to test its efficacy as an inhibitor of the myelotoxic effect exerted by chemotherapy, in vivo. MF, administered after chemotherapy, restored the number of white blood cells and yielded an increased percentage of neutrophils
compared with the decline in these parameters after administration of chemotherapy alone. Thus, it is indicated that MF exerted
a systemic anti tumor and chemoprotective effect when given orally. It can be concluded that it is bioavailable and is not
biodegradable in the digestive system. MF may be considered as a potential therapy for the prevention of tumor spread.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
86.
87.
88.
89.
Immunoprecipitating factors of vaccinia virus 总被引:4,自引:0,他引:4