全文获取类型
收费全文 | 32130篇 |
免费 | 2987篇 |
国内免费 | 1469篇 |
专业分类
耳鼻咽喉 | 286篇 |
儿科学 | 407篇 |
妇产科学 | 560篇 |
基础医学 | 6767篇 |
口腔科学 | 610篇 |
临床医学 | 1700篇 |
内科学 | 3925篇 |
皮肤病学 | 717篇 |
神经病学 | 1655篇 |
特种医学 | 530篇 |
外国民族医学 | 15篇 |
外科学 | 2565篇 |
综合类 | 4300篇 |
现状与发展 | 6篇 |
预防医学 | 956篇 |
眼科学 | 296篇 |
药学 | 3330篇 |
2篇 | |
中国医学 | 722篇 |
肿瘤学 | 7237篇 |
出版年
2024年 | 54篇 |
2023年 | 483篇 |
2022年 | 674篇 |
2021年 | 1230篇 |
2020年 | 970篇 |
2019年 | 1056篇 |
2018年 | 913篇 |
2017年 | 877篇 |
2016年 | 819篇 |
2015年 | 1140篇 |
2014年 | 1638篇 |
2013年 | 1658篇 |
2012年 | 1466篇 |
2011年 | 1857篇 |
2010年 | 1715篇 |
2009年 | 1725篇 |
2008年 | 1757篇 |
2007年 | 1809篇 |
2006年 | 1637篇 |
2005年 | 1560篇 |
2004年 | 1488篇 |
2003年 | 1411篇 |
2002年 | 1212篇 |
2001年 | 1098篇 |
2000年 | 990篇 |
1999年 | 813篇 |
1998年 | 717篇 |
1997年 | 623篇 |
1996年 | 519篇 |
1995年 | 412篇 |
1994年 | 281篇 |
1993年 | 211篇 |
1992年 | 155篇 |
1991年 | 124篇 |
1990年 | 85篇 |
1989年 | 87篇 |
1988年 | 106篇 |
1987年 | 75篇 |
1986年 | 91篇 |
1985年 | 158篇 |
1984年 | 174篇 |
1983年 | 90篇 |
1982年 | 110篇 |
1981年 | 87篇 |
1980年 | 84篇 |
1979年 | 64篇 |
1978年 | 58篇 |
1977年 | 55篇 |
1976年 | 43篇 |
1975年 | 36篇 |
排序方式: 共有10000条查询结果,搜索用时 62 毫秒
61.
A. G. Douglas-Jones H. Navabi J. M. Morgan B. Jasani 《Virchows Archiv : an international journal of pathology》1997,430(5):373-379
Immunocytochemically detectable MT and p53 have been found more commonly in comedo DCIS of the breast with high-grade cytology.
The aim of this study is to confirm these findings and to investigate the relationship between MT and p53 in a single large
series of cases of DCIS of the breast. To this end, 127 cases of DCIS were classified histologically according to architecture,
cytonuclear differentiation (grade), presence and extent of intraduct necrosis, and using the Van Nuys system. Sections were
immunostained for p53 and MT (E9) using established techniques, and the extent and intensity of staining were assessed semi-quantitively.
The results confirmed that there was generally more MT and p53 positivity in poorly differentiated (grade 3) DCIS with extensive
necrosis and that MT expression was greater in grade 2 lesions than p53 expression. However, overall there was no statistically
significant correlation between p53 and MT staining. The results indicate that MT and p53 overexpression may arise from independent
mechanisms in early breast neoplasia.
Received: 3 July 1996 / Accepted: 5 November 1996 相似文献
62.
63.
P53、P16、Bcl-2基因及产物在原发性肺癌中的表达及其临床病理意义 总被引:3,自引:0,他引:3
目的 :探讨原发性肺癌 Mtp5 3、p16、Bcl- 2的异常表达与肺癌发生、发展的关系 ,以及它们之间的调控关系。 方法 :用免疫组化技术检测 (L SAB) 114例原发性肺癌组织中 p5 3、p16、Bcl- 2的表达。并用 PCR技术对 6 2例 p16蛋白丢失的肺癌组织中 p16外显子 2 (p16 E2 )的缺失进行分析。 结果:p5 3蛋白异常表达与肺癌组织学类型、分化程度无关 (P >0 .0 5 ) ,但与淋巴结转移情况有关 (P >0 .0 5 )。 p16蛋白阳性表达率与肺癌的组织学类型无关 ,但是其表达水平与非小细胞肺癌 (NSCL C)的细胞分化程度和淋巴结转移密切相关 (P <0 .0 5 )。 NSCL C中 p16E2的缺失率为 45 .2 %,其缺失水平随淋巴结转移和组织学分级的升高而升高 (P <0 .0 5 )。 SCL C(小细胞肺癌 )和正常肺组织中无 p16 E2的缺失。 Bcl- 2在小细胞肺癌中阳性率 6 2 .2 %显著高于 Sq Ca(鳞癌 )的 2 5 %和 Ad Ca(腺癌 )的 9.1%(P <0 .0 5 ) ,与细胞分化程度和淋巴结转移情况无关。另外 ,p5 3与 p16蛋白之间存在调控关系。 结论 :(1) p16、p5 3、Bcl- 2的异常参与肺癌的发生、发展过程。 (2 ) p16基因及产物的异常表达与 NSCL C的组织学分级和淋巴结转移相关 ,可能参与 NSCL C的发生、发展和转移过程。 (3) Bcl- 2反映 SCL C的分之生物学行为和临床 相似文献
64.
Dario Roccatello Marco Formica Guido Cavalli Maria C. Amprimo Maria G. Pignatelli Paolo Costa Ruggero de Paulis Giacomo Quattrocchio rea Molino Gianbeppe Giordano 《Artificial organs》1990,14(1):69-72
Neutrophil oxidative metabolism, C3d and beta 2 microglobulin levels, were assessed in nine consecutive patients undergoing cardiopulmonary bypass surgery with polypropylene hollow fiber oxygenators for open cardiac operations. Generation of oxygen free radicals by neutrophils was measured as luminol-enhanced chemiluminescence after stimulation with opsonized Zymosan and phorbol myristate acetate. A significant increase in light emission was detected by using both of the chemiluminescence stimulators. Moreover, a remarkable and significant increase in C3d levels was found already at 10 min. Conversely minimal changes in levels of beta 2 microglobulin were detected during cardiopulmonary bypass surgery. These data suggest that the impact of the patient blood with the foreign surface of cardiopulmonary bypass results in activation of phagocyte cells with increased potential in oxygen consumption. These effects could be partially complement-mediated. 相似文献
65.
Abstract: We analyzed the expression of CEA, CA19-9, CA125, CA15-3 (DF3), PCNA and p53 immunohistochemically in 14 tissue specimens of mucosal cancers in adenoma, seven tubulovillous adenoma specimens, and 16 tubular adenoma specimens. The rates of positive staining for mucosal cancer in adenoma, tubulovillous adenoma and tubular adenoma specimens, respectively, were: for CEA: 100%, 85.7% and 75%; for CA19-9: 71.4%, 71.4% and 56.2%; for CA125:0%, 0% and 0%;for CA15-3 (DF3): 64.3 %, 0% and 0 %; for PCNA: 100%, 88.9% and 56.2%; and for p53: 35.7%, 0% and 0% . The results suggest that the expressions of CEA, CA19-9, CA15-3 (DF3), PCNA and p53 are related to colorectal tumorigenesis. None of the specimens studied showed staining for CA125, suggesting that CA125 is not involved in the early stages of colorectal carcinogenesis. There was no significant difference in the rates of positive staining for CEA and CA19-9 among mucosal cancer in adenoma, tubular adenoma and tubulovillous adenoma specimens. However, the rates of positive staining for PCNA and p53 were significantly higher in mucosal cancer in adenoma specimens than for tubular adenoma specimens (p<0.05), and the rate of CA15-3 (DF3) positive staining was significantly higher for mucosal cancer in adenoma than for tubulovillous adenoma (p<0.01) and tubular adenoma (p< 0.001) specimens. Therefore, the CA15-3 (DF3) antigen is an immunohistochemical marker for colorectal carcinomas. The present results suggest that CA15-3 (DF3), PCNA and p53 play important roles in the genesis of colorectal adenomas. 相似文献
66.
67.
Heterogeneous proteolytic specificity and activity of the house dust mite proteinase allergen Der p I 总被引:3,自引:0,他引:3
C. R. A. HEWITT H. HORTON R. M. JONES D. I. PRITCHARD† 《Clinical and experimental allergy》1997,27(2):201-207
Background Exposure of the skin or respiratory tract to proteinases is frequently associated with allergic sensitization. This is of particular significance in the domestic indoor environment where the proteolytic activity of Der p I, the group I allergen of the house dust mite Dermatophagoides pteronyssinus, may influence the allergenicity of mites. Using class-specific proteinase inhibitors and active-site affinity chromatography, we have previously shown that Der p I exhibits a mixed cysteine-serine proteinase activity. Measurement of the amount of cleavage, however, did not determine whether the inhibitors used were targeting exactly the same proteolytic mechanism. Objective To resolve this issue, we have examined whether the cleavage specificity of the cysteine and serine proteinase activities of Der p I was the same. Methods HPLC and mass spectrometry were used to analyse and identify the products of a Der p I-digested peptide substrate and thus identify the peptide bonds cleaved. Results Der p I cleaves different peptide bonds, depending upon the class of proteolytic mechanism used. In the model peptide substrate insulin B chain, the cysteine and serine proteinase activities of Der p I showed preference for glutamic acid and arginine respectively in the P1 position. Conclusion These data suggest the existence of more than one mechanistic form of the allergen immunologically identified as Der p I. If proteolytic activity is indeed a function of allergenicity, this information may have important implications for the pathogenicity of Der p I and the ability of innate antiproteinase defences in the respiratory tract to prevent immune sensitization. 相似文献
68.
69.
R. DE BOER W. A. D. VAN DER HOEVEN S. O. STAPEL 《Clinical and experimental allergy》1995,25(8):765-770
Background: Fluctuations in the level of mite allergens in domestic house dust are the result of changes in the balance between synthesis, removal and decay. Purely physical forces as well as enzymatic degradation, mediated by house dust inhabiting microbes, may contribute to the decay of allergens in domestic dust. Knowledge about the speed of decay is essential for an understanding of the dynamics of allergen levels. Objective: The present study is a quantitative assessment of the speed of decay at nine combinations of temperature (15°C, 20°C and 25°C) and relative humidity (33%, 55% and 75%). Methods: Samples of mite infested material of an old rug were stored at these temperature/relative humidity-combinations for 6, 12 or 18 months, after the mites were killed by cither a freezing treatment or an acaricide (lindane). The microbes living in the rug presumably survive these treatments. Concentrations of Der p I and Der p II + Der f II. in extracts of the rug material, were measured by a radio immunoassay. Results: No significant changes in the levels of Der p I and Der p II +Der f II, could be detected even after 11/2 year at a high temperature and humidity. Conclusion: These findings incidate that mite allergens can be extremely stable under normal domestic circumstances. 相似文献
70.
p53 Protein expression in laryngeal squamous cell carcinomas bearing wild-type and mutated p53 gene 总被引:1,自引:0,他引:1
G. PRUNERI L. PIGNATARO N.S. FRACCHIOLLA S. FERRERO P. CAPACCIO N. CARBONI A. OTTAVIANI A.T. MAIOLO A. NERI & R. BUFFA 《Histopathology》1996,28(6):513-519
We performed an immunohistochemical analysis to investigate the expression of p53 protein in a panel of 18 laryngeal squamous cell carcinomas, 15 primary tumours and three in relapse, previously analysed by us for the presence of p53 gene mutations. Dysplastic and/or normal surrounding mucosa was evaluated in 15 different tumours. The results of our study are the following: (1) expression of p53 protein was observed in one out of five tumours positive for p53 gene mutations (20%) and in 10 out of 13 (80%) negative cases; (2), p53 protein over-expression was frequently observed in normal and/or dysplastic mucosa surrounding either wild-type (7/11) or mutated p53 tumours (2/4); (3), p53 immunoreactive cells showed a pattern of distribution in normal and mildly/moderately dysplastic mucosa (basal layers), different from that in severely dysplastic mucosa (whole thickness). These data further support the hypothesis that p53 protein over-expression may be a marker of the earliest phases of multistep tumorigenesis in laryngeal squamous cell carcinoma. 相似文献