全文获取类型
收费全文 | 537379篇 |
免费 | 297192篇 |
国内免费 | 52532篇 |
专业分类
耳鼻咽喉 | 5013篇 |
儿科学 | 8121篇 |
妇产科学 | 7522篇 |
基础医学 | 120904篇 |
口腔科学 | 7486篇 |
临床医学 | 96201篇 |
内科学 | 137964篇 |
皮肤病学 | 8081篇 |
神经病学 | 36231篇 |
特种医学 | 18678篇 |
外国民族医学 | 118篇 |
外科学 | 71682篇 |
综合类 | 98108篇 |
现状与发展 | 53篇 |
一般理论 | 52篇 |
预防医学 | 60921篇 |
眼科学 | 24303篇 |
药学 | 87483篇 |
227篇 | |
中国医学 | 59753篇 |
肿瘤学 | 38202篇 |
出版年
2023年 | 6170篇 |
2022年 | 13500篇 |
2021年 | 16858篇 |
2020年 | 16019篇 |
2019年 | 21454篇 |
2018年 | 22489篇 |
2017年 | 22366篇 |
2016年 | 20428篇 |
2015年 | 24586篇 |
2014年 | 27526篇 |
2013年 | 27045篇 |
2012年 | 34201篇 |
2011年 | 37667篇 |
2010年 | 31680篇 |
2009年 | 36527篇 |
2008年 | 27886篇 |
2007年 | 24681篇 |
2006年 | 23584篇 |
2005年 | 23108篇 |
2004年 | 20719篇 |
2003年 | 19211篇 |
2002年 | 18042篇 |
2001年 | 18921篇 |
2000年 | 14105篇 |
1999年 | 19160篇 |
1998年 | 17488篇 |
1997年 | 17407篇 |
1996年 | 17471篇 |
1995年 | 17437篇 |
1994年 | 16870篇 |
1993年 | 14878篇 |
1992年 | 15009篇 |
1991年 | 14017篇 |
1990年 | 12723篇 |
1989年 | 12332篇 |
1988年 | 11673篇 |
1987年 | 11039篇 |
1986年 | 10298篇 |
1985年 | 9219篇 |
1984年 | 7029篇 |
1983年 | 6920篇 |
1982年 | 7819篇 |
1981年 | 7310篇 |
1980年 | 6965篇 |
1979年 | 6863篇 |
1978年 | 5966篇 |
1977年 | 6226篇 |
1976年 | 5839篇 |
1975年 | 5557篇 |
1974年 | 5150篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
991.
Use of cocaine concurrently with alcohol is prevalent among cocaine addicts. Cocaine has been shown to inhibit phytohemagglutinin- and ConA-induced proliferation of T-lymphocytes, NK cell cytotoxicity, and phagocytic activity of peritoneal macrophages. In some studies no effects of cocaine on the immune response have been observed, although on the contrary, others show it increased the NK cell activity and serum antibody response to T-dependent antigen. Effects of cocaine on the immune system may be mediated by its neurostimulatory action on the hypothalamo-pituitary-adrenal axis. ACTH, beta-endorphine, and corticosterone released under the action of cocaine exert various inhibitory effects on the immune function. We studied the immunotoxic effect of cocaine, combination of cocaine with ethanol, and cocaethylene, a derivative formed from cocaine and ethanol in the body, on the mitogen-stimulated production of cytokines by splenocytes. C57BL mice were injected twice daily with 20 mg/kg cocaine or equivalent dose of cocaethylene and received a liquid Lieber-DeCarli diet containing ethanol (26% of total calories) or isocaloric amount of maltose-dextrin. After 3 weeks of treatment, cocaine and cocaethylene caused a significant decrease of the spleen weight and total number of splenocytes. In splenocytes isolated from the cocaine- or cocaethylene-treated mice, mitogen-stimulated production of gamma-interferon, tumor necrosis factor, and interleukin-2 was suppressed, in all cases more severely when cocaethylene was used. Thus, formation of cocaethylene during simultaneous consumption of cocaine and ethanol may enhance the immunotoxicity of cocaine. 相似文献
992.
993.
K. M. Weidenheim I. Epshteyn W. K. Rashbaum W. D. Lyman 《Journal of neurocytology》1994,23(6):343-353
Summary Although the presence of radial glia, astrocytes, oligodendrocytes and microglia has been reported in the human foetal spinal cord by ten gestational weeks, neuroanatomic studies employing molecular probes that describe the interrelated development of these cells from the late first trimester through the late second trimester are few. In this study, immunocytochemical methods using antibodies to vimentin and glial fibrillary acidic protein were used to identify radial glia and/or astrocytes. An antibody to myelin basic protein was used for oligodendrocytes and myelin; and, an antibody to phosphorylated high and medium molecular weight neurofilaments identified axons. Lectin histochemistry usingRicinus communis agglutinin-I was employed to identify microglia. Vibratome sections from 35 human foetal spinal cord ranging in age from 9–20 gestation weeks were studied. By 12 gestational weeks, vimentin-positive radial glia were present at all three levels of the spinal cord. Their processes were easily identified in the dorsal two-thirds of cord sections, and reaction product for vimentin was more intense at cervical and thoracic levels than lumbosacral sections. By 15 gestational weeks, vimentin-positive processes were radially arranged in the white matter. At this time, glial fibrillary acidic protein-positive astrocytes were more obvious in both the anterior and anterolateral funiculi than in the dorsal funiculus, and the same rostral to caudal gradient was seen for glial fibrillary acidic protein as it was for vimentin. Myelin basic protein expression followed similar temporal and spatial patterns.Ricinus communis agglutinin-I labelling revealed more microglia in the white matter than in grey matter throughout the spinal cord from 10–20 gestational weeks. By 20 gestational weeks, the gradients of glial fibrillary acidic protein and vimentin expression were more difficult to discern. White matter contained more microglia than grey matter. These results suggest that astrocytes as well as oligodendrocytes follow anterior-to-posterior and rostral-to-caudal developmental patterns in the human foetus during middle trimester development. 相似文献
994.
Hiroyoshi Komai Yasuaki Naito Keiichi Fujiwara Yasuzo Noguchi 《The Japanese Journal of Thoracic and Cardiovascular Surgery》2002,50(2):55-58
OBJECTIVE: Since we developed the procedure in 1996, we have now performed 100 pediatric open heart operations using a lower midline skin incision and a minimal sternotomy approach. METHODS AND RESULTS: To elucidate the benefits of this approach, we analyzed these 100 cases retrospectively. There was no death, and no major complication, caused by this approach, and the resulting scarring in each patient is difficult to be seen under a common undershirt. CONCLUSION: This review shows that the technique of a lower midline skin incision and minimal sternotomy approach is a safe reliable and cosmetically advantageous method for a pediatric cardiac operation. 相似文献
995.
Monoclonality of both pale cells and cuboidal cells of sclerosing hemangioma of the lung. 总被引:26,自引:0,他引:26 下载免费PDF全文
S. Niho K. Suzuki T. Yokose T. Kodama Y. Nishiwaki H. Esumi 《The American journal of pathology》1998,152(4):1065-1069
Sclerosing hemangioma of the lung remains poorly understood, and it is still unclear whether this lesion is neoplastic or not. It consists of two major cell types, pale cells and cuboidal cells. We analyzed the clonality of each cell types from six female cases of surgically resected sclerosing hemangioma. The pale cells and cuboidal cells were separated by microdissection from methanol-fixed sections, and DNA was extracted for clonal analysis based on an X-chromosome-linked polymorphic marker, the human androgen receptor (HUMARA) gene or the phosphoglycerate kinase (PGK) gene. The HUMARA and PGK genes were found to be amplified with or without digestion by the methylation-sensitive restrictive endonuclease HpaII. Five of six cases were informative. Pale cells and cuboidal cells showed the same monoclonality in all of the informative cases, whereas the control cells showed a polyclonal pattern. Our results demonstrated that sclerosing hemangioma is caused by monoclonal expansion of cells, confirming that it is a neoplasia. Moreover, the present data indicate that both pale cells and cuboidal cells are derived from the same cell. 相似文献
996.
Examination of spinal cord in diseases of the craniocervical junction and high cervical spine. 总被引:2,自引:2,他引:0 下载免费PDF全文
A simple necropsy technique for the removal of the craniocervical junction was devised: a relatively small specimen comprising part of the clivus, the foramen magnum, and cervical vertebral canal is removed in one piece with the medulla and spinal cord inside, and examined systematically after fixation. This method, used in a series of patients with chronic craniocervical instability, allows both good clinicopathological correlations to be made and histological changes in the lower medulla or upper cervical cord segments to be related to sites of extrinsic compression. 相似文献
997.
998.
999.
1000.