全文获取类型
收费全文 | 37142篇 |
免费 | 2624篇 |
国内免费 | 72篇 |
专业分类
耳鼻咽喉 | 325篇 |
儿科学 | 1323篇 |
妇产科学 | 1040篇 |
基础医学 | 5024篇 |
口腔科学 | 497篇 |
临床医学 | 4717篇 |
内科学 | 6653篇 |
皮肤病学 | 629篇 |
神经病学 | 3950篇 |
特种医学 | 760篇 |
外国民族医学 | 4篇 |
外科学 | 3291篇 |
综合类 | 345篇 |
一般理论 | 45篇 |
预防医学 | 4930篇 |
眼科学 | 579篇 |
药学 | 2539篇 |
中国医学 | 36篇 |
肿瘤学 | 3151篇 |
出版年
2024年 | 45篇 |
2023年 | 328篇 |
2022年 | 619篇 |
2021年 | 1277篇 |
2020年 | 782篇 |
2019年 | 1144篇 |
2018年 | 1298篇 |
2017年 | 937篇 |
2016年 | 1094篇 |
2015年 | 1133篇 |
2014年 | 1470篇 |
2013年 | 2075篇 |
2012年 | 3018篇 |
2011年 | 3226篇 |
2010年 | 1713篇 |
2009年 | 1444篇 |
2008年 | 2586篇 |
2007年 | 2605篇 |
2006年 | 2342篇 |
2005年 | 2233篇 |
2004年 | 1956篇 |
2003年 | 1705篇 |
2002年 | 1722篇 |
2001年 | 268篇 |
2000年 | 230篇 |
1999年 | 262篇 |
1998年 | 346篇 |
1997年 | 267篇 |
1996年 | 189篇 |
1995年 | 200篇 |
1994年 | 143篇 |
1993年 | 137篇 |
1992年 | 104篇 |
1991年 | 87篇 |
1990年 | 82篇 |
1989年 | 75篇 |
1988年 | 79篇 |
1987年 | 57篇 |
1986年 | 71篇 |
1985年 | 39篇 |
1984年 | 40篇 |
1983年 | 47篇 |
1982年 | 38篇 |
1981年 | 34篇 |
1980年 | 27篇 |
1979年 | 19篇 |
1978年 | 26篇 |
1977年 | 27篇 |
1974年 | 20篇 |
1970年 | 20篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
U Mandel H Clausen P Vedtofte H S?rensen E Dabelsteen 《Journal of oral pathology》1988,17(9-10):506-511
Cell surface carbohydrates are excellent markers for cellular differentiation and maturation due to great structural and antigenic diversity and to known precursor/product relations. Several blood group related carbohydrate antigens were analyzed in human labial stratified non-keratinized epithelium from 16 healthy individuals by immunohistology using monoclonal antibodies. The expression of these antigens was correlated with erythrocyte phenotype and saliva secretor status. Three distinct compartments of the epithelium were found and defined by the sequential expression of derivatives of Type 2 chain structures: lower, confined to basal cell layers (N-acetyllactosamine), middle, to parabasal cell layers (H) and upper, to spinous cell layers (Le(y)/Le(x)). Although the antigens are related to blood group antigens they are largely expressed independently of the ABO, Lewis and secretor types, and may therefore serve as "universal" markers in differentiation studies of normal and pathological epithelium. 相似文献
92.
W. E. Adam M. Clausen D. Hellwig E. Henze F. Bitter 《European journal of nuclear medicine and molecular imaging》1988,13(12):637-647
Myocardial scanning (MS) and radionuclide ventriculography (RNV) are the foundation of nuclear cardiology. These procedures aim in two completely different directions: RNV tries to image heart motion, that is, mechanical (pump) function, and therefore belongs to the group of first-order functional imaging (FI, imaging mechanical function), whereas MS is based on myocardial metabolism, and therefore can be attributed to third-order functional imaging (metabolism). This statement is relevant for the assessment of the clinical position of RNV: Third-order (metabolism) functional imaging is the domain of nuclear medicine (NM), whereas first-order FI has to face the competition of alternative noninvasive procedures such as ultrasound (US), digital subtraction angiography (DSA), computer tomography (CT), and nuclear magnetic resonance (NMR). The domain of RNV includes stages two (acute infarction) and three (postinfarction period) of coronary arterial disease (CAD). The advantageous combination of quantitative data on global, left ventricular (LV) function and imaging of regional motion ensures the superiority of RNV over US. However, RNV is inferior to MS in physical examinations in the preinfarction stage of CAD, whereas US is clearly inferior to both NM procedures. Recent progress could be attained by gated SPECT (GASPECT). A proposal is presented for simplification of this time-consuming procedure. Technetium-labeled isonitriles offer the chance for the combination of perfusion-motion imaging of the myocardium. However, even standard RNV offers new possibilities. The multitude of parameters produced by quantitation has not yet been exploited completely. This can be done by discriminant analysis. The computer finds out an optimal subset from the whole set of parameters for the solution of a significant clinical problem. The software learns to find the label of a special pathognomonic entity. This computer work is supported by a relational data bank (Oracle) and an optical disk. Two examples for the effectiveness of the computer in problem solving are presented. It is concluded that RNV, even in the very competitive class of first-order functional imaging, enjoys a preferred position. The future indeed seems brighter because labeled isonitriles offer the chance for the combination of perfusion-motion imaging of the myocardium.Dedicated to Prof. Heinz Hundeshagen on the occasion of his 60th birthday 相似文献
93.
Brian D Perkins Claire S Nicholas Lisa M Baye Brian A Link John E Dowling 《Developmental dynamics》2005,233(2):680-694
Several molecules, such as growth factors and neurotrophic factors, are required both for the differentiation of specific retinal cell types and the long-term cell survival of all retinal neurons. As diffusible factors, these molecules act non-cell-autonomously. Here, we describe the loss of function phenotype for dazed (dzd), a gene that acts cell-autonomously for retinal cell survival and affects the differentiation of rod photoreceptors and the Muller glia. By 3 days after fertilization, dazed mutant embryos have small eyes and slight heart edema. Acridine orange staining indicated a significant degree of retinal cell death occurring by 48 hr after fertilization, and histological analysis revealed that dying cells were found in the inner and outer nuclear layers and near the marginal zones. Although molecular and morphological differentiation of the inner retina and cone photoreceptors occurred, rod photoreceptors failed to differentiate beyond a small patch in the ventral retina and rod precursors failed to respond to exogenously added retinoic acid, which normally potentiated rod differentiation. Mosaic analysis indicated that the dazed gene acts cell-autonomously for rod production and cell survival, as dazed clones failed to produce rods outside the ventral patch and dazed cells were not maintained in wild-type hosts. Raising mutants under constant light resulted in severe retinal degeneration, whereas raising embryos under constant darkness did not provide any additional protection from cell death. Behavioral analysis showed that a subpopulation of adult fish that were heterozygous for the dazed mutation had elevated visual thresholds and were night blind, suggesting that dazed may also be required for long-term dim-light vision. Taken together, our studies suggest a role for the dazed gene in rod and Muller cell development and overall retinal cell survival and maintenance. 相似文献
94.
Hewlett D Warner C Brenner LK 《The Journal of allergy and clinical immunology》2003,112(6):1246; author reply 1246-1246; author reply 1247
95.
96.
Research over the past decade has provided a new understanding of genital herpes transmission and measures that can reduce transmission risk. It is unclear, however, how those affected by genital herpes access and interpret this information to make decisions about risk behaviours. This study measured how people with genital herpes and their partners perceived prevention methods, barriers and facilitating factors, and information sources. Formative evaluation was conducted, and survey data were collected from visitors to four websites (n=1849). Results suggest that the prevention messages of refraining from sex during disease outbreaks and condom use have had the greatest reach. Misconceptions about the potential role of suppressive antiviral therapy for genital herpes prevention persist among a substantial percentage of respondents. Accurate information concerning transmission between outbreaks, the effectiveness of condoms and the role of antiviral medication is critical in preventing the spread of genital herpes. 相似文献
97.
Prerequisites for translating intervention research findings into practice are maintenance of results, generalization of effects and consistency of implementation. This report presents 12 months follow-up information on a randomized 2x2 factorial trial evaluating the incremental effects of adding (1) telephone follow-up or (2) a community resources utilization component to a basic touchscreen computer-assisted dietary goal-setting intervention for 320 type 2 diabetes patients. All conditions evidenced significant improvement from baseline to the 12 months follow-up across behavioral, biological and psychosocial measures. There were few consistent differences between conditions, but results were robust across interventionists and clinics. The telephone follow-up component appeared to enhance long-term results on some measures. When considered along with earlier results from a randomized trial that included a control condition without goal setting, it is concluded that this basic goal-setting intervention can be consistently implemented by a variety of interventionists and produce lasting improvements. 相似文献
98.
99.
100.
Johnson JG Cohen P Kotler L Kasen S Brook JS 《Journal of consulting and clinical psychology》2002,70(5):1119-1128
Longitudinal data were used to investigate whether anxiety, depressive, disruptive, personality, or substance use disorders are associated with risk for the development of eating disorders during adolescence or early adulthood. Psychiatric disorders were assessed among 726 youths from a random community sample during adolescence and early adulthood. Depressive disorders during early adolescence were associated with elevated risk for the onset of eating disorders, dietary restriction, purging behavior, and recurrent weight fluctuations after preexisting eating problems and other psychiatric disorders were controlled statistically. Disruptive and personality disorders were independently associated with elevated risk for specific eating or weight problems. The present findings suggest that depressive disorders during early adolescence may contribute to the development of eating disorders during middle adolescence or early adulthood. 相似文献