全文获取类型
收费全文 | 1116720篇 |
免费 | 61663篇 |
国内免费 | 1500篇 |
专业分类
耳鼻咽喉 | 14906篇 |
儿科学 | 37756篇 |
妇产科学 | 30018篇 |
基础医学 | 178090篇 |
口腔科学 | 29950篇 |
临床医学 | 95369篇 |
内科学 | 205195篇 |
皮肤病学 | 26039篇 |
神经病学 | 76952篇 |
特种医学 | 44138篇 |
外国民族医学 | 211篇 |
外科学 | 165269篇 |
综合类 | 16676篇 |
现状与发展 | 2篇 |
一般理论 | 220篇 |
预防医学 | 84241篇 |
眼科学 | 26059篇 |
药学 | 85541篇 |
3篇 | |
中国医学 | 2138篇 |
肿瘤学 | 61110篇 |
出版年
2018年 | 13171篇 |
2017年 | 10879篇 |
2016年 | 11189篇 |
2015年 | 13652篇 |
2014年 | 16307篇 |
2013年 | 21952篇 |
2012年 | 35586篇 |
2011年 | 33355篇 |
2010年 | 18918篇 |
2009年 | 19133篇 |
2008年 | 29164篇 |
2007年 | 32134篇 |
2006年 | 32214篇 |
2005年 | 38617篇 |
2004年 | 39396篇 |
2003年 | 34178篇 |
2002年 | 28891篇 |
2001年 | 46733篇 |
2000年 | 46128篇 |
1999年 | 41376篇 |
1998年 | 10396篇 |
1997年 | 8728篇 |
1996年 | 9118篇 |
1995年 | 8526篇 |
1992年 | 32980篇 |
1991年 | 34157篇 |
1990年 | 34372篇 |
1989年 | 33309篇 |
1988年 | 30688篇 |
1987年 | 30253篇 |
1986年 | 28462篇 |
1985年 | 26925篇 |
1984年 | 19812篇 |
1983年 | 16800篇 |
1982年 | 8769篇 |
1981年 | 7919篇 |
1979年 | 19504篇 |
1978年 | 13703篇 |
1977年 | 11223篇 |
1976年 | 11018篇 |
1975年 | 13420篇 |
1974年 | 15702篇 |
1973年 | 14952篇 |
1972年 | 14186篇 |
1971年 | 13735篇 |
1970年 | 12733篇 |
1969年 | 12134篇 |
1968年 | 11410篇 |
1967年 | 10309篇 |
1966年 | 9173篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
81.
82.
S Dvorakova E Vaclavikova A Ryska J Cap P Vlcek J Duskova D Kodetova V Holub Z Novak B Bendlova 《Experimental and clinical endocrinology & diabetes》2006,114(4):192-196
Medullary thyroid carcinoma (MTC) is a rare form of thyroid cancer representing about 10% of all thyroid malignancies. It occurs mostly as a sporadic tumor or in association with autosomal dominant inherited cancer syndromes--multiple endocrine neoplasia (MEN) types 2A and 2B and familial MTC. Germline mutations in exons 8, 10, 11, 13, 14, 15 and 16 of the RET proto-oncogene are found in most of the familial cases. There are only a few published data reporting multiple germline mutations in the RET proto-oncogene. We have detected double germline mutations in 2 different exons on the same RET allele in two MEN 2 families. In the MEN 2A family, double germline mutation in exons 10 (Cys620Phe) and 13 (Tyr791Phe) was detected. In the MEN 2B family, beside the classical germline mutation in exon 16 (Met918Thr) a second germline mutation in exon 13 (Tyr791Phe) was found. This study revealed that MEN 2 syndromes can also be caused by double germline mutations in the RET proto-oncogene and these families can be added to small worldwide cohort of families with multiple germline mutations. 相似文献
83.
E Chankiewitz D Peschke L Herberg I Bazwinsky E Mühlbauer H-J Br?mme E Peschke 《Experimental and clinical endocrinology & diabetes》2006,114(5):262-269
The New Zealand obese mouse (NZO/Hl) is characterised by hereditary obesity and type-2 diabetes, including insulin resistance, hyperinsulinaemia, and glucose intolerance. In other diabetic models, it has been revealed that the proper functioning of the glucose transporter isoform 2 (GLUT2) is essential for adequate secretion of insulin. The aim of this study was to compare the distribution of islet cells and GLUT2, as well as the expression of GLUT2-mRNA, in the pancreas of NZO mice and metabolically unimpaired NMRI (Naval Medical Research Institute) mice. Pancreas tissue was obtained from different stages of development. For molecular determination of the expression level of GLUT2-mRNA, total-RNA was extracted from the pancreas and analysed by quantitative real-time RT-PCR. All investigated NZO mice displayed increased weight, elevated hyperinsulinaemia, and slightly enhanced blood glucose levels compared with the NMRI control mice. By means of immunofluorescence microscopy drastically reduced insulin levels were detected, which might be compensated by the observed islet cell hyperplasia and hypertrophy. Furthermore, the normally peripheral localisation of the alpha-cells within islets was disturbed. By contrast, there were no changes in somatostatin cell distribution. However, considerable differences appeared with regard to GLUT2: whereas the beta-cells of NMRI mice showed dense immunostaining of the GLUT2 transporter on the cell surface, in all age groups of NZO mice, GLUT2 on the plasma membranes was reduced and dispersed in the cytoplasm. These findings agree with the molecular biological results, which displayed decreased mRNA-expression of GLUT2. In summary, the observed alteration of islet morphology and of GLUT2 expression in diabetic mice complements our previous results from a superfusion protocol and further clarifies the mechanisms of diabetogenesis in NZO mice. 相似文献
84.
V. Schmitz U. P. Neumann G. Puhl Z. V. Tran P. Neuhaus J. M. Langrehr 《American journal of transplantation》2006,6(2):379-385
Choledochojejunostomy (CJS) is commonly used for biliary reconstruction in liver transplantation for primary sclerosing cholangitis (PSC). We alternatively performed choledochoduodenostomy (CDS) and side-to-side choledochodocholedochstomy in a large cohort of patients. Fifty-one patients with PSC, transplanted between 1988 and 2000, were analyzed retrospectively. Biliary reconstruction was CDS in 25 (49%), CJS in 20 (39%) and CC in 6 transplantations (12%). Biliary leaks occurred in the early follow-up (< or =41 days) only in CDS patients (20%). However, in the late follow-up (>4 months), stricturing of anastomosis was found once in CDS (4%) and CJS (5%). Later (>9 months), intrahepatic bile duct strictures were diagnosed in four CDS (16%), one CJS (5%) and one CC (17%) patient(s). In 48% of CDS (12/25), 60% of CJS (12/20) and 17% of CC (1/6) at least one incidence of cholangitis was observed. Overall, biliary complication rates were significantly higher in CDS (40%) than CJS (10%) and CC (17%); of those none in CC and 12% in CDS were anastomosis-related. Graft/patient survival showed no significant differences among groups. Based on our results we consider CJS the standard method for biliary reconstruction in PSC; however, in selected cases where CJS is difficult to accomplish because of previous surgery or for retransplantation, CDS may present an alternative technique. 相似文献
85.
86.
87.
Joseph V. Terza 《Health services & outcomes research methodology》2006,6(3-4):177-198
The typical empirical study in health services and outcomes research is aimed at estimating the causal effect that an exogenously imposed condition (e.g. a policy mandate) will have (or has had) on a specified outcome of interest. Controlling for unobservable confounding influences is of primary importance in such analyses. The instrumental variables (IV) method has been widely used for this purpose in the linear regression context. The present paper examines the pros and cons of alternative versions of the generalized method of moments (GMM) [of which the IV estimator is a special case] for the estimation of policy effects when endogeneity is present in a nonlinear regression setting. We show that conventional GMM is difficult to implement for policy analysis because it does not typically accommodate symmetry—similar treatment of both observable and unobservable confounders in the regression specification. Although, simple additive (nonsymmetric) regression specifications afford practical GMM estimators, they are difficult to defend from both intuitive and conceptual standpoints. Moreover, as we show via simulation, if symmetry is ignored and conventional GMM is applied based on an incorrectly specified non-symmetric model, then policy analytic estimates can be seriously biased. As a result, prospects for the development and application of intuitive consistent GMM-based policy effect estimators are dim. The problem stems from the reasonable desire on the part of the researcher to derive GMM estimators in the nonlinear framework that are based solely upon the conventional minimalist linear IV assumptions. We show, in the context of our formulation of a simple but consistent alternative to GMM in the probit case, that intuitively appealing additional assumptions about the data generating process of the policy variable will often be sufficient for the development of desirable alternatives to the GMM. 相似文献
88.
89.
90.