全文获取类型
收费全文 | 44842篇 |
免费 | 4849篇 |
国内免费 | 1209篇 |
专业分类
耳鼻咽喉 | 224篇 |
儿科学 | 1062篇 |
妇产科学 | 348篇 |
基础医学 | 15441篇 |
口腔科学 | 547篇 |
临床医学 | 3155篇 |
内科学 | 7509篇 |
皮肤病学 | 1290篇 |
神经病学 | 1608篇 |
特种医学 | 2474篇 |
外国民族医学 | 9篇 |
外科学 | 2919篇 |
综合类 | 4910篇 |
现状与发展 | 14篇 |
预防医学 | 1835篇 |
眼科学 | 327篇 |
药学 | 2686篇 |
8篇 | |
中国医学 | 1221篇 |
肿瘤学 | 3313篇 |
出版年
2024年 | 90篇 |
2023年 | 658篇 |
2022年 | 1122篇 |
2021年 | 1655篇 |
2020年 | 1456篇 |
2019年 | 1733篇 |
2018年 | 1850篇 |
2017年 | 1664篇 |
2016年 | 1593篇 |
2015年 | 1775篇 |
2014年 | 2556篇 |
2013年 | 3046篇 |
2012年 | 2315篇 |
2011年 | 2649篇 |
2010年 | 2117篇 |
2009年 | 1969篇 |
2008年 | 2045篇 |
2007年 | 1961篇 |
2006年 | 1785篇 |
2005年 | 1553篇 |
2004年 | 1551篇 |
2003年 | 1369篇 |
2002年 | 1109篇 |
2001年 | 1033篇 |
2000年 | 879篇 |
1999年 | 803篇 |
1998年 | 850篇 |
1997年 | 778篇 |
1996年 | 720篇 |
1995年 | 718篇 |
1994年 | 708篇 |
1993年 | 631篇 |
1992年 | 387篇 |
1991年 | 303篇 |
1990年 | 341篇 |
1989年 | 276篇 |
1988年 | 204篇 |
1987年 | 156篇 |
1986年 | 150篇 |
1985年 | 328篇 |
1984年 | 367篇 |
1983年 | 232篇 |
1982年 | 292篇 |
1981年 | 232篇 |
1980年 | 184篇 |
1979年 | 174篇 |
1978年 | 120篇 |
1977年 | 102篇 |
1976年 | 131篇 |
1975年 | 74篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
Ian Gravenor Trudy L. Norton Pamela Ritchie Emma Flint John D. Norton 《Developmental and comparative immunology》1995,19(6):507-523
Recently generated anti-Xenopus T cell monoclonal antibodies (mAbs) to the 120 kDA XTLA-1 determinant and against the putative CD5 and CD8 homologues, together with anti-IgM and anti-MHC class II mAbs, are used in dual colour flow cytometric experiments to characterize cell surface antigenic expression on lymphocytes in thymus and spleen of Xenopus laevis during larval and early adult life and also in metamorphosis-inhibited animals. Histological confirmation of T cell emergence early in larval ontogeny is supplied by cryostat sections stained for CD8. Five-day thymectomy i.e. prior to T-lineage cell differentiation in the thymus, abolishes T cell marker expression in the spleen for up to 1 year. Moreover, late larval (20 days) or early adult (3 months) thymectomy (i.e. removal after peripheralization of T cells has occurred) also leads to severe depletion of mAb-defined T cells in the spleen. 相似文献
102.
M. R. Angi F. Forattini M. Chilosi A. Cipriani G. De Caro G. Semenzato 《International ophthalmology》1990,14(1):1-11
Summary Sarcoidosis is a multisystem disease characterized by enhanced immune responses at sites of involvement. To elucidate the immunopathogenesis of ophthalmic lesions, cell infiltrates in biopsies from conjunctiva and other tissues involved (lungs, lymph nodes, skin) were studied in 26 patients with active sarcoidosis in order to define the surface phenotype and the distribution of cells in granulomatous lesions. Biopsy specimens were also stained for detection of immunoglobulins, complement and fibrinogen deposits. The data demonstrate a lymphocytes/macrophages interaction in the central core of granulomatous areas as the crucial event that initiates the maintains the state of inflammation: at all sites of disease activity is present a compartmentalization of T-cells expressing a helper-related phenotype which account for the great majority of infiltrating cells both in the early lesions (aggregate of macrophages surrounded by lymphocytic infiltrate) and in well-organized sarcoid granulomata. The presence of plasma cells and immunoglobulin deposits may represent an epiphenomenon in line with the helper infiltration, suggesting a local hyper-reactivity of the B-cells immune system. This study suggests some immunopathogenetic mechanisms leading to the formation and growth of conjunctival sarcoid granulomata. 相似文献
103.
Caroline S. Drugan rea Stone Steve M. Game Stephen S. Prime 《Journal of oral pathology & medicine》1997,26(7):327-333
This study examined the mitogenic response to keratinocyte growth factor (KGF) of normal and tumour-derived human oral keratinocytes in which the degree of cellular differentiation was known and in contiguous fibroblast cultures derived from the malignant epithelial cultures. Keratinocytes, but not fibroblasts, were stimulated by KGF. There by demonstrating epithelial target cell specificity of the ligand. KGF-induced stimulation of the tumour-derived keratinocytes cultured in the absence of the 3T3 fibroblast support broadly correlated with the degree of cellular differentiation; well-differentiated keratinocytes were stimulated more by KGF than their less differentiated counterparts. Malignant oral keratinocytes expressed KGF cell surface receptors (KD 451-709 pM; receptors/cell 2306-413645), but KGF receptor mRNA did not correlate with either KGF-induced mitogenesis or the degree of epithelial cell differentiation. When the tumour-derived keratinocytes were cultured in the presence of 3T3 fibroblasts, the mitogenic response to KGF was comparable to normal epithelial cells. The results suggest that KGF-mediated growth stimulation may not be significant in providing a selective advantage for the growth of malignant keratinocytes. 相似文献
104.
A. V. Filatov S. A. Prokof'ev V. V. Shcherbukhin 《Bulletin of experimental biology and medicine》1992,114(5):1656-1659
Institute of Immunology, Ministry of Health of Russian. (Presented by Academician of the Russian Academy of Medical Sciences R. V. Petrov.) Translated from Byulleten Éksperimental'noi Biologii i Meditsiny, Vol. 114, No. 11, pp. 506–508, November, 1992. 相似文献
105.
Nobutaka Eiraku Shinji Ijichi Shinji Yashiki Mitsuhiro Osame Shunro Sonoda 《Journal of neuroimmunology》1992,37(3):223-228
The in vitro proliferation of peripheral blood lymphocytes (PBLs) without any mitogenic stimulation is one of the hallmarks of human T lymphotropic virus type I (HTLV-I) infection. Recent evidence suggests a difference in the degree of the phenomenon between HTLV-I-associated myelopathy/tropical spastic paraparesis (HAM/TSP) and asymptomatic HTLV-I carriers (AC). In this article, we demonstrated several alterations in the features of the in vitro transformed lymphocytes between patients with HAM/TSP (n = 16) and AC (n = 8). The percentages of total CD8+ and CD8+CD28+ cells were significantly increased in the in vitro proliferating T lymphocytes derived from the patients with HAM/TSP when compared to those from AC. HAM/TSP was segregated from AC by the high degree of the proliferation of CD8+CD28+ cells. The expression of HTLV-I-specific antigens on the cultured PBLs was detected only in the subjects which showed low CD8+CD28+/CD4+ ratio of the in vitro proliferating lymphocytes. These findings suggest that this phenomenon distinguishes HAM/TSP from AC, not only in quantity but also in quality. 相似文献
106.
Carlotta Castagnoli Claudia Trombotto Sabzima Ondei Maurizio Stella Maurizio Calcagni Gilberto Magliacani Simone Teich Alasia 《Burns : journal of the International Society for Burn Injuries》1997,23(7-8):565-572
In this study, skin-infiltrating cells were characterized in both the active and remission phases of post-burn hypertrophic scar biopstes. Immunohistochemistry examination of active phase samples showed an abundant presence of Langerhans cells, T cells, macrophages, a low presence of natural killer cells and the lack of B lymphocytes. In active hypertrophic scars T lymphocytes infiltrate deep into the superficial dermis and are also observed in the epidermis: CD3+ cells were present at about 222±107 per 0.25 mm2. In particular the analysis of lymphocyte subpopulations showed that CD4+ T cells predominate in the dermis as well as in the epidermis of active hypertrophic scars whereas CD8+ cells were less well represented (CD4/CD8 ratio is 2.06). This distribution was also shown in remission phase samples and in normotrophic scar specimens, although the lymphocyte number was significantly lower. Approximately 70 per cent of T lymphocytes present in the tissue involved in active phase hypertrophic scar samples were activated (positive with anti-HLA-DR and IL-2 receptor antibodies) which is significantly higher than remission phase hypertrophic and normotrophic scars, in which positivity was 40 and 38 per cent, respectively. Upon activation, the lesional lymphocytes release several cytokines, locally and transiently, that interact with specific receptors in response to different stimulation. Central to the immune hypothesis of hypertrophic scars is that some of the T-cell lymphokines act on keratinocytes, fibroblasts and other cell types to induce changes characteristic of these scars. The presence and close proximity of activated T lymphocytes and antigen-presenting cells of various phenotypes in both the epidermis and dermis of hypertrophic tissues provides strong circumstantial evidence of a local immune response. However, the manner in which T cells achieve and maintain their activated state in hypertrophic tissues in not yet known, and both antigen-dependent and independent mechanisms may contribute. 相似文献
107.
Purified secretory acetylcholinesterase (sAChE) from Trichostrongylus colubriformis was used as a candidate vaccine against mixed T. colubriformis, Haemonchus contortus and C. oncophora challenge infections of sheep. Cross species protection was achieved with an average reduction in worm burden of all species of 31%, rising to 58% in individual cases. There was no consistent reduction in faecal egg counts and increases in anti-T. colubriformis sAChE IgG antibody levels following vaccination were modest. We suggest that improved antigen delivery systems will result in increased host protection. 相似文献
108.
静脉用丙种球蛋白治疗新生儿重症感染对细胞免疫功能的影响 总被引:1,自引:0,他引:1
应用静脉注丙球(IVIG),配合抗生素(An)治疗重症感染新生儿12例,在观察疗效及不良反应的同时,通过检测患儿治疗前后T细胞亚群及白细胞介素Ⅱ(IL-2)产生水平的变化,观察IVIG对细胞免疫功能的影响。结果显示:患儿CD_3~+、CD_4~+、CD_8~+细胞及IL-2产生水平均明显低于正常同龄新生儿。经IVIG+An及单用An治疗后,T细胞各亚群及IL-2水平均明显增高。IVIG组与An组比较,诒疗后IVIG组CD_4~+细胞明显高于An组,IL-2水平也较An组为高,但无统计学意义。疗效观察,中毒症状及原发病体征好转消失时间IVIG组较An组明显缩短。本文还就IVIG对细胞免疫功能影响的可能机制进行了讨论。 相似文献
109.
A quantitative immunocytochemical study of large granular lymphocytes (LGLs) in the normal cervix and in human papillomavirus (HPV) associated disease was performed using a panel of monoclonal antibodies which included those for LGL surface markers CD56, CD16, and CD57. Only CD56-positive cells were found within the ectocervical epithelium and these cells increased in number in cervical intraepithelial neoplasia (CIN) in comparison with normal cervix. Examination of serial sections and double labelling suggests that these cells are CD3+, CD8+, CD56+, CD16+. The observed increase in number of this subset was not associated specifically with HPV infection but was related to CIN. Lymphocytes expressing all three LGL markers were found in the stroma and CD16(+)-positive cells clustered around endocervical glands with occasional cells extending into the endocervical epithelium. These results indicate that a small subset of LGLs which express T-cell markers is increased in number in CIN. Cells expressing classical NK markers are restricted to the stroma and are not found within the ectocervical epithelium. 相似文献
110.
谢林 《湖南中医药大学学报》1994,14(2):1-3
本文从髌骨软骨软化症的病因病理出发,阐述了活血化瘀疗法治疗髌骨软骨软化症的作用及其原理,列举了活血化瘀法在该病治疗中的具体运用,同时强调了在辨证施治基础上活血化瘀的重要性。 相似文献