全文获取类型
收费全文 | 384954篇 |
免费 | 24812篇 |
国内免费 | 3162篇 |
专业分类
耳鼻咽喉 | 5243篇 |
儿科学 | 8263篇 |
妇产科学 | 10145篇 |
基础医学 | 53671篇 |
口腔科学 | 11873篇 |
临床医学 | 30990篇 |
内科学 | 78984篇 |
皮肤病学 | 8591篇 |
神经病学 | 27438篇 |
特种医学 | 14086篇 |
外国民族医学 | 88篇 |
外科学 | 61030篇 |
综合类 | 11355篇 |
现状与发展 | 5篇 |
一般理论 | 65篇 |
预防医学 | 17964篇 |
眼科学 | 9631篇 |
药学 | 31679篇 |
11篇 | |
中国医学 | 2565篇 |
肿瘤学 | 29251篇 |
出版年
2021年 | 2921篇 |
2019年 | 2919篇 |
2018年 | 4716篇 |
2017年 | 3657篇 |
2016年 | 3707篇 |
2015年 | 4312篇 |
2014年 | 6042篇 |
2013年 | 7805篇 |
2012年 | 10548篇 |
2011年 | 10690篇 |
2010年 | 6633篇 |
2009年 | 6211篇 |
2008年 | 9855篇 |
2007年 | 10656篇 |
2006年 | 10506篇 |
2005年 | 9526篇 |
2004年 | 8988篇 |
2003年 | 8683篇 |
2002年 | 8324篇 |
2001年 | 28355篇 |
2000年 | 28845篇 |
1999年 | 23698篇 |
1998年 | 5191篇 |
1997年 | 4277篇 |
1996年 | 3848篇 |
1995年 | 3496篇 |
1994年 | 3120篇 |
1993年 | 2845篇 |
1992年 | 16054篇 |
1991年 | 14817篇 |
1990年 | 14160篇 |
1989年 | 13966篇 |
1988年 | 12586篇 |
1987年 | 12061篇 |
1986年 | 11105篇 |
1985年 | 10320篇 |
1984年 | 6912篇 |
1983年 | 5600篇 |
1982年 | 2718篇 |
1979年 | 5478篇 |
1978年 | 3347篇 |
1977年 | 2971篇 |
1975年 | 2641篇 |
1974年 | 3065篇 |
1973年 | 2867篇 |
1972年 | 2828篇 |
1971年 | 2773篇 |
1970年 | 2511篇 |
1969年 | 2543篇 |
1968年 | 2250篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
151.
We established a MAb N-25 reacted with a minor unknown antigen (AgX) in a commercially available GQ1b sample. It also recognized minor antigens in bovine brain (X-1, 2, 3, 4 and 5) and cultured neural cell lines (X-1). AgX is identical to X-5. X-5 is sialidase sensitive and has the common structure as X-1, which is resorcinol positive. These results suggested that novel gangliosides exist in bovine brain and neural cell lines. 相似文献
152.
Allografts of CNS tissue possess a blood-brain barrier. II. Angiogenesis in solid tissue and cell suspension grafts 总被引:2,自引:0,他引:2
R D Broadwell H M Charlton P S Ebert W F Hickey Y Shirazi J Villegas A L Wolf 《Experimental neurology》1991,112(1):1-28
Angiogenesis and patency of blood vessels were analyzed qualitatively in solid CNS and peripheral tissue syngeneic, allogeneic, and xenogeneic grafts and in individual cell suspension grafts of astrocytes, fibroblasts, PC12, and three additional tumor cell lines placed intracerebrally in adult host mice. Postgrafting survival times were 1 day through 4 weeks. The patency of graft vessels was determined in sections from immersion-fixed tissues incubated to reveal the endogenous peroxidase activity of host red cells trapped within the lumen of blood vessels. Additionally, horseradish peroxidase (HRP) was administered intravenously to live hosts; HRP labels host brain and graft vessels on the luminal surface and reveals the presence or absence of a blood-brain barrier (BBB) within the grafts. The origins of blood vessels supplying solid tissue xenografts were identified immunohistochemically with primary antibodies against host (athymic AKR mice) and donor (fetal Lewis rats) major histocompatibility complex (MHC) class I. Blood vessels supplying solid CNS grafts at 1-7 days post-transplantation were identified ultrastructurally and possessed interendothelial tight junctional complexes; however, they were not perfused with either host blood or blood-borne HRP prior to 8 days. Graft vessels at 10 days were outlined consistently by peroxidase-positive red cells in immersion-fixed material and labeled with blood-borne HRP. These vessels provided a BBB to the circulating HRP and exhibited interendothelial tight junctions. Evidence of angiogenesis within solid anterior pituitary grafts and the variety of cell suspension grafts was obtained prior to 3 days post-transplantation in immersion-fixed preparations; the vessels, with the notable exception of those supplying astrocyte cell suspensions, failed to present a BBB to blood-borne peroxidase. Endothelia in the solid pituitary allografts and the PC12 cell grafts were highly fenestrated and exhibited open interendothelial junctions; those in the tumor and fibroblast cell grafts, for the most part, appeared nonfenestrated, and many possessed open interendothelial junctional complexes. Immunostaining for host and donor MHC class I revealed that donor blood vessels predominate over host vessels in CNS xenografts and supply pituitary xenografts exclusively; in both preparations, donor vessels were not identified within the host CNS. Because cell suspension grafts were derived from endothelia-free preparations grown in culture, blood vessels supplying these grafts were necessarily of host CNS origin and manifested a morphological transformation from a BBB to a non-BBB endothelium. The data suggest that angiogenesis in solid CNS grafts placed into the adult host CNS, compared to similarly placed solid peripheral tissue/cell suspension grafts, is not rapid.(ABSTRACT TRUNCATED AT 400 WORDS) 相似文献
153.
K Tanaka Y Miyake S Sasaki Y Ohya S Miyamoto I Matsunaga T Yoshida Y Hirota H Oda 《Magnesium research》2006,19(4):268-275
There have only been a few studies on the role of mineral intake in tooth loss. We investigated the association between mineral intake and the prevalence of tooth loss in Japan. We used the baseline data on 1002 pregnant women who were enrolled in the Osaka Maternal and Child Health Study between November 2001 and March 2003. Tooth loss was defined as the previous extraction of one or more teeth. Nutrient intake was assessed by a validated diet history questionnaire. Prevalence odds ratios and confidence intervals were estimated by applying a multiple logistic regression model. The adjusted odds ratio upon comparison of the highest quartile with the lowest quartile of magnesium intake was 0.64 (95% confidence interval, 0.42-0.99), showing a tendency for an inverse dose-response relationship (p for linear trend = 0.05). There were no associations between the level of consumption of calcium, phosphate, iron, zinc, or copper and tooth loss. The present findings suggest that intake of magnesium is related to reduced prevalence of tooth loss among young Japanese women. 相似文献
154.
155.
156.
157.
Selda Sarikaya Bektas Acikg?z Ismail Hakki Tekk?k Y Yücel Güngen 《Journal of clinical neuroscience》2007,14(9):901-904
We report a 24-year-old woman with an intramedullary conus ependymoma associated with holocord syringohydromyelia and syringobulbia. The tumor was removed and surgery for decompression of the syringohydromyelia was not considered at the first operation. In the follow-up examinations, MRI showed significant and steady improvement of syringohydromyelia. Symptoms associated with syringohydromyelia also disappeared. The cause of syringohydromyelia accompanying intradural spinal cord tumors appears to be either direct blockade of the central canal or secondary interruption of the central canal flow by compression of the perimedullary cerebrospinal fluid flow. As removal of the mass often corrects both these likely causes of the syringohydromyelia, no additional treatment for the drainage of the hydromyelia cavity syrinx is usually necessary. 相似文献
158.
159.
160.
Effects of immobilization and footshock stress on locomotor activity in different areas of an open field were examined in mice. Center region activity, peripheral region activity and total activity were used as measurement indices. These results indicate that both immobilization and footshock stress significantly increased total activity across 24 min of behavioral testing. Further analyses revealed that the difference in total activity between the experimental and control groups were mainly attributal to an increase in center region activity. Both stress manipulations markedly augmented peripheral region activity for only the first 6 min. More important, when the proportion of center to peripheral activity was used as an index, both experimental groups manifested an inverted U shape relationship with the maximum effect occurring between 13-18 min of behavioral testing. Similarities of these activity measures in response to different stressors suggests that common neurochemical and/or neurohormonal mechanisms may mediate these behavioral changes. 相似文献