全文获取类型
收费全文 | 196103篇 |
免费 | 18050篇 |
国内免费 | 8531篇 |
专业分类
耳鼻咽喉 | 2439篇 |
儿科学 | 4487篇 |
妇产科学 | 2076篇 |
基础医学 | 39102篇 |
口腔科学 | 5667篇 |
临床医学 | 14945篇 |
内科学 | 27739篇 |
皮肤病学 | 5068篇 |
神经病学 | 10628篇 |
特种医学 | 5974篇 |
外国民族医学 | 125篇 |
外科学 | 16545篇 |
综合类 | 28866篇 |
现状与发展 | 55篇 |
预防医学 | 5845篇 |
眼科学 | 3744篇 |
药学 | 14566篇 |
36篇 | |
中国医学 | 5953篇 |
肿瘤学 | 28824篇 |
出版年
2024年 | 423篇 |
2023年 | 2847篇 |
2022年 | 4977篇 |
2021年 | 7025篇 |
2020年 | 6324篇 |
2019年 | 6412篇 |
2018年 | 6611篇 |
2017年 | 6741篇 |
2016年 | 6996篇 |
2015年 | 7937篇 |
2014年 | 11539篇 |
2013年 | 12791篇 |
2012年 | 10966篇 |
2011年 | 12354篇 |
2010年 | 10184篇 |
2009年 | 9800篇 |
2008年 | 10225篇 |
2007年 | 10383篇 |
2006年 | 9395篇 |
2005年 | 8562篇 |
2004年 | 7641篇 |
2003年 | 6654篇 |
2002年 | 5464篇 |
2001年 | 4748篇 |
2000年 | 3932篇 |
1999年 | 3531篇 |
1998年 | 3389篇 |
1997年 | 3042篇 |
1996年 | 2685篇 |
1995年 | 2428篇 |
1994年 | 2196篇 |
1993年 | 1823篇 |
1992年 | 1403篇 |
1991年 | 1293篇 |
1990年 | 1045篇 |
1989年 | 970篇 |
1988年 | 890篇 |
1987年 | 703篇 |
1986年 | 667篇 |
1985年 | 970篇 |
1984年 | 933篇 |
1983年 | 649篇 |
1982年 | 696篇 |
1981年 | 559篇 |
1980年 | 472篇 |
1979年 | 390篇 |
1978年 | 277篇 |
1977年 | 214篇 |
1976年 | 201篇 |
1975年 | 101篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
91.
We investigated populations of the infiltrating cells in Bowen's disease (BD) and squamous cell carcinoma (SCC), both of which arose in the same patient, using the Avidin-Biotin-peroxidase complex method with eight monoclonal antibodies. T lymphocytes were most predominant among infiltrating cells; NK cells, B cells, and monocytes were rarely seen in either BD or SCC. Analysis of subsets of the infiltrating T lymphocytes revealed that the number of suppressor/cytotoxic (s/c) T cells was twice that of helper/inducer (h/i) T cells in BD, while the number of s/c T cells was lower than that of h/i T cells in SCC. The immunohistochemical results in the present case differed from those of predominant infiltration of h/i T cells and of s/c T cells in three other reports of BD and SCC. These results suggest that the population of the cellular infiltrates may be modulated by the nature of tumors and by the immuno-competent state of the hosts. 相似文献
92.
93.
C Monteiro B Fernandes J Reis O Tellechea J Freitas A Figueiredo 《Journal of the European Academy of Dermatology and Venereology》2002,16(6):615-617
We report the case of a 75-year-old-woman who presented with bilateral scalp ulcerations and blindness, accompanied by severe headache and scalp tenderness, due to bilateral temporal arteritis without systemic involvement. A biopsy taken from the border of an ulceration showed evidence of giant cell arteritis. She was treated with oral prednisone, 60 mg per day. The ulcerations healed in a few weeks but the vision loss was irreversible. This case highlights for temporal arteritis the importance of accurate and timely diagnosis as well as the need for prompt therapy with systemic steroids in order to avoid major complications, namely loss of vision. It also demonstrates that scalp necrosis and ulcerations are skin signs associated with a poor prognosis. 相似文献
94.
95.
获得性纯红再障患者外周血T细胞亚群分析 总被引:7,自引:0,他引:7
目的 本研究通过分析获得性纯红再障患者外周血T细胞亚群 ,进一步探讨该病的细胞免疫发病机制。方法 用抗人CD3、CD4、CD8、IFN γ及IL 4单抗结合人外周血单个核细胞 ,流式细胞术分析单个核细胞中CD3 +、CD4+、CD8+细胞数Th1、Th2、Tc1、Tc2细胞数以及CD4+/CD8+、Th1/Th2、Tc1/Tc2比值。结果 贫血组患者 ,外周血CD3 +细胞和CD8+细胞明显增加 (P <0 .0 1) ,CD4+/CD8+比例倒置 (P <0 .0 5 ) ;Tc2细胞明显增加 (P <0 .0 5 ) ,Tc1/Tc2比值降低(P <0 .0 5 ) ,治疗后血象恢复的患者各增高的亚群细胞均有所恢复 ,接近正常。结论 在获得性纯红再障患者T细胞明显增高 ,其中主要是CD8+细胞 ,而在CD8+细胞中 ,是Tc2细胞发挥了重要作用。经治疗有效的患者 ,其增高的T细胞亚群降低 ,提示以纠正病人细胞免疫异常为主的治疗方案有益于获得性纯红再障的治疗。 相似文献
96.
97.
98.
We have investigated the time course and magnitude of cellular degeneration in the ganglion cell layer and the presumptive amacrine and bipolar regions of the inner nuclear layer during the development of the retina in the rat. Pyknotic profiles are present in the ganglion cell layer during the first 2 postnatal weeks, reaching peak numbers during the first 4 postnatal days (corresponding to the time of greatest loss of ganglion cells and their axons: Potts et al., '82; Lam et al., '82; Perry et al., '83). Two observations suggest that the majority of pyknotic profiles present in the ganglion cell layer during the second postnatal week are not ganglion cells. First, following injection of kainic acid into one superior colliculus, degenerating ganglion cells in the contralateral retina are cleared within 24-48 hours. Therefore, since most ganglion cell and axon loss occurs within the first postnatal week, few of the pyknotic profiles present in the second week are likely to be ganglion cells. Second, the time course of cellular degeneration in the ganglion cell layer during the second postnatal week follows a very similar pattern to that seen in the presumptive amacrine sublayer of the inner nuclear layer. Such a correspondence suggests that two phases of cell death occur in the ganglion cell layer: during the first postnatal week the majority of dying cells are ganglion cells, and in the second, most cell death is due to a loss of displaced amacrine cells. In the inner nuclear layer pyknotic profiles are most numerous in the presumptive amacrine region on postnatal days 6 and 7, and in the presumptive bipolar region on day 10. Synaptogenesis in the inner plexiform layer occurs later but reflects the order of cell death. Thus, conventional (presumed amacrine) synapses were first observed on day 11 and synaptic ribbons (indicative of bipolar synapses) on day 13. These observations suggest that amacrine and bipolar cells initiate synapses only after their numbers have stabilized. 相似文献
99.
F. Ide K. Mishima H. Yamada I. Saito A. Tanaka K. Kusama 《Journal of oral pathology & medicine》2007,36(8):505-510
BACKGROUND: Nevic corpuscle (NC), a stacked lamellar structure reminiscent of Meissner corpuscle, is frequently observed in dermal melanocytic nevi. Although the heading 'neurotized' is classically used for these nevi, the exact neural nature of NC has been a topic of considerable debate. Neurotized nevi have received little attention in the dental literature, and there was no information on NC in oral melanocytic nevi. METHODS: Six cases of oral intramucosal nevi with a significant number of NC (two completely and four partially neurotized nevi) were examined immunohistochemically and ultrastructurally. RESULTS: NC was composed of closely piled laminar cells devoid of visible melanin. NC and associated spindle nevus cells were immunopositive for S-100 protein but negative for HMB-45, myelin basic protein and epithelial membrane antigen. Within NC, no reactivity for neurofilament protein, protein gene product 9.5 or peripherin was evident. Numerous CD34-positive dendritic cells were located between nevus cells and often encircled NC. Ultrastructurally, NC consisted of concentrically layered elongated cells with a slender lamellated cytoplasm rich in thin filaments and pinocytotic vesicles. Their cytoplasmic processes were focally covered by external basal lamina and continuous to spindle nevus cells. Occasional NC cells contained a few melanosomes. There was no interposed axon in NC. CONCLUSIONS: Despite the close resemblance to Meissner corpuscle, NC showed no axonal supply. NC cells lacked terminal Schwannian differentiation and appeared to be modified melanocytes with some perineurial ultrastructural characteristics. The presence of CD34-positive cells, presumably corresponding to endoneurial fibroblasts, further supports an organizational relationship of NC and peripheral nerve sheath elements. 相似文献
100.
A series of 237 appendices was studied immunohistochemically for neurogenous hyperplasia. This was observed in 195 cases. It was possible to trace a continuum from appendices with intact lumens, featuring intramucosal neurogenous hyperplasia often with co-existent submucosal and muscular nerve growth, to obliterated specimens whose axial portions were composed of varying proportions of nerve tangles and fibrous tissue. Predominantly fibrotic specimens were considered as end-stages of this process. Stromal, argyrophilic cells lying amidst the nerve elements were prominent in the early, non-obliterated cases; their number decreased in the obliterated nerve rich specimens and such cells became inapparent in the late fibrotic stage. Repeated minimal subclinical attacks of inflammation are thought to trigger this lesion. 相似文献