全文获取类型
收费全文 | 5715篇 |
免费 | 573篇 |
国内免费 | 172篇 |
专业分类
耳鼻咽喉 | 62篇 |
儿科学 | 109篇 |
妇产科学 | 96篇 |
基础医学 | 618篇 |
口腔科学 | 123篇 |
临床医学 | 609篇 |
内科学 | 1023篇 |
皮肤病学 | 135篇 |
神经病学 | 286篇 |
特种医学 | 124篇 |
外国民族医学 | 2篇 |
外科学 | 514篇 |
综合类 | 487篇 |
预防医学 | 560篇 |
眼科学 | 196篇 |
药学 | 763篇 |
6篇 | |
中国医学 | 239篇 |
肿瘤学 | 508篇 |
出版年
2024年 | 15篇 |
2023年 | 93篇 |
2022年 | 277篇 |
2021年 | 429篇 |
2020年 | 254篇 |
2019年 | 241篇 |
2018年 | 278篇 |
2017年 | 195篇 |
2016年 | 236篇 |
2015年 | 282篇 |
2014年 | 358篇 |
2013年 | 327篇 |
2012年 | 457篇 |
2011年 | 477篇 |
2010年 | 287篇 |
2009年 | 214篇 |
2008年 | 289篇 |
2007年 | 234篇 |
2006年 | 248篇 |
2005年 | 227篇 |
2004年 | 176篇 |
2003年 | 155篇 |
2002年 | 117篇 |
2001年 | 72篇 |
2000年 | 73篇 |
1999年 | 60篇 |
1998年 | 42篇 |
1997年 | 36篇 |
1996年 | 37篇 |
1995年 | 30篇 |
1994年 | 28篇 |
1993年 | 20篇 |
1992年 | 28篇 |
1991年 | 21篇 |
1990年 | 21篇 |
1989年 | 14篇 |
1988年 | 21篇 |
1987年 | 16篇 |
1986年 | 19篇 |
1985年 | 6篇 |
1984年 | 7篇 |
1983年 | 7篇 |
1982年 | 2篇 |
1981年 | 3篇 |
1980年 | 3篇 |
1979年 | 6篇 |
1977年 | 2篇 |
1975年 | 2篇 |
1974年 | 2篇 |
1972年 | 2篇 |
排序方式: 共有6460条查询结果,搜索用时 15 毫秒
41.
受体-A蛋白融合蛋白制备抗P物质受体血清及其特性WalterK.K.Ho(何国强);AlexisP.K.Che,郑德枢(香港中文大学;香港生物化学系,香港沙田;广州医学院神经科学研究所,广州510182)本文报告了用直肠杆菌表达P物质受体-A蛋白融合... 相似文献
42.
VEGF,bFGF及PCNA在宫颈癌中的表达及其与肿瘤增殖和血管生成的关系 总被引:9,自引:0,他引:9
目的 :探讨有关细胞因子在调控宫颈癌增殖及其血管生成中的作用。方法 :应用免疫组织化学及其组织形态学定量分析方法 ,对血管内皮细胞生长因子 (VEGF) ,碱性成纤维细胞生长因子(b FGF)和增殖细胞核抗原 (PCNA)在宫颈癌中的表达进行研究。结果 :1肿瘤细胞增殖与 VEGF的表达呈正向关系 ,而与 b FGF的表达无关 ;2 VEGF,b FGF的表达分别与微血管密度有正相关性 ,而当 VEGF和 b FGF共同表达时 ,微血管密度显著增加 ;3VEGF,b FGF在不同个体的表达具有异质性。结论 :VEGF有促进肿瘤细胞增殖及血管生成的作用。VEGF,b FGF在肿瘤血管生成过程中可能起协同作用 相似文献
43.
目的:说明PCNA含量及DNA含量联合检测在子宫内膜癌及癌前病变中的诊断意义;两种取材方法对结果的影响,以探讨临床工作采用新鲜标本作为早期诊断的辅助手段是可行的。 相似文献
44.
目的:回顾58例双瓣替换术体外循环管理状况,总结双瓣替换术中灌注技术。方法:对58例风湿性心脏瓣膜病人施行二尖瓣、主动脉瓣替换术中体外循环手术的临床资料、心肺转汉方法和心肌保护中的难点及处理进行回顾总结分析。结果:58例中早期死亡2例,死亡率3.45%R。结论:只有良好的体外循环灌注技术和心肌保护,才能保证双瓣替换术病人顺利渡过围术期,降低手术死亡率。 相似文献
45.
Jastrzebska M Torbus-Lisiecka B Pieczul-Mróz J Chełstowski K Naruszewicz M 《Materia medica Polona. Polish journal of medicine and pharmacy》1997,29(1-4):3-7
The concentrations of fibrinogen (Fb) and the activities of factor VII (F VIIC) and antithrombin III (AT III) both in men less than 55 years old with a history of myocardial infarction (MI) and with normolipemia (MI-NLP) or hyperlipoproteinemia (MI-HLP) and in their sons have been measured. A significantly higher levels of Fb were found in both MI groups. Significantly higher levels of F VIIC and AT III were found only in the MI-NLP group. No lipid or haemostatic disorders were noted in sons. Furthermore, a positive correlation between the level of F VIIC and triglycerides (TG) or total cholesterol (TCh) in the patients and sons was revealed. A positive correlation was found between: (a) Fb levels in MI-HLP patients and in their sons; (b) TG levels in MI-HLP patients and in their sons; and (c) AT III activity in MI patients and in their sons. Fibrinogen appears to be associated with ischemic heart disease more closely than factor VII, the latter being strongly linked with hypertriglyceridemia. Elevated activities of AT III may reflect the haemostatic response to the prothrombotic state in IHD on the one hand whereas they may contribute to the development of IHD on the other. 相似文献
46.
A retrospective study of anaemia in pregnancy in rural Kelantan was conducted. The study sample consist of 9,860 mothers who had antenatal care at one of the 102 rural health clinics selected and had delivered a live baby. Anaemia in pregnancy was determined by reviewing the antenatal records for the haemoglobin level recorded at the first and last antenatal visit. Estimation of haemoglobin was done either by photocalorimetric methods or the Sahli's method in these rural clinics. At the time of booking, 47.5% of the mothers were anaemic by WHO criteria (Hb < 11.0 g/dl), with 1.9% having less than 9.0 g/dl. Age of mother, parity and late gestational age at the first antenatal visit were associated with anaemia during pregnancy at the time of booking. However, practise of contraception by the mother did not show any association with anaemia in pregnancy. There were 594 mothers (6.0%) who delivered a baby weighing less than 2.5 kg. There was no association between the low birth weight of the child and the status of anaemia in the mother at the last antenatal visit. 相似文献
47.
Summary In order to study the cellular origin of muscularization in non-muscular arterioles of the lung, the pulmonary vascular pericytes-culture
was established. The terminal lung tissue of the rat was taken out and minced. Then 0.5 % of type IV collagenase solution
was added for digestion and the microvascular segments were obtained by screening. The targeted cells were cultured by “selective
conditioned media”. Under phase-contrast microscope, the cultured cells were large in size with ragged margin and numerous
pseudopodia, which imparted tubule-like structure. There was no contact inhibition in growing cells, so multiple layers developed.
When they were confluent, there were morphologically no “hillock and dale” growth pattern as in smooth muscle cells or “weave-like”
pattern as in fibroblasts. The ultrastructure of cultured cells showed numerous digital processes, moderate amount of rough
and smooth endoplasmic reticulum, rich Golgi’s apparatus, microfilaments, few lysosomes without myofilaments and dense bodies.
Immunohistochemical staining revealed that the cultured pericytes had same kind of cellular skeletal protein, α-SM-actin,
like smooth muscle cells. The cultured cells also exhibited positive reaction to CD34 antigen and S-100 antigen, which were negative in smooth muscle cells and fibroblasts. The cell growth pattern, ultrastructure
and immunological phenotype suggested that the cultured cells had characteristics of vascular pericytes. Pericytes are one
of the components of microvascular cells, and the establishment ofin vitro culture technique of pericytes is of significance for further exploration of the muscularization of non-muscular arterioles
in lung and the mechanism of structural remodeling of pulmonary vessels.
This project was supported by the grant of National Nature Sciences Foundation of China (No. 39570289). 相似文献
48.
Since the seminal work of the Gestalt psychologists, there has been great interest in understanding what factors determine the perceptual organization of images. While the Gestaltists demonstrated the significance of grouping cues such as similarity, proximity and good continuation, it has not been well understood whether their catalog of grouping cues is complete--in part due to the paucity of effective methodologies for examining the significance of various grouping cues. We describe a novel, objective method to study perceptual grouping of planar regions separated by an occluder. We demonstrate that the stronger the grouping between two such regions, the harder it will be to resolve their relative stereoscopic depth. We use this new method to call into question many existing theories of perceptual completion (Ullman, S. (1976). Biological Cybernetics, 25, 1-6; Shashua, A., & Ullman, S. (1988). 2nd International Conference on Computer Vision (pp. 321-327); Parent, P., & Zucker, S. (1989). IEEE Transactions on Pattern Analysis and Machine Intelligence, 11, 823-839; Kellman, P. J., & Shipley, T. F. (1991). Cognitive psychology, Liveright, New York; Heitger, R., & von der Heydt, R. (1993). A computational model of neural contour processing, figure-ground segregation and illusory contours. In Internal Conference Computer Vision (pp. 32-40); Mumford, D. (1994). Algebraic geometry and its applications, Springer, New York; Williams, L. R., & Jacobs, D. W. (1997). Neural Computation, 9, 837-858) that are based on Gestalt grouping cues by demonstrating that convexity plays a strong role in perceptual completion. In some cases convexity dominates the effects of the well known Gestalt cue of good continuation. While convexity has been known to play a role in figure/ground segmentation (Rubin, 1927; Kanizsa & Gerbino, 1976), this is the first demonstration of its importance in perceptual completion. 相似文献
49.
A methanolic extract of the whole plant of Elephantopus mollis was found to contain lupeol, lupeol acetate, epifriedelinol, molephantin, and 2-de-ethoxy-2-methoxyphantomolin, as well as a new sesquiterpene lactone determined to be 2-de-ethoxy-2-hydroxyphantomolin. 相似文献
50.
DNA测序建立甘肃当归、大黄种子rRNA基因图谱的研究 总被引:3,自引:0,他引:3
目的:对甘肃地道性中药材当归、大黄种子中rRNA基因内转录间隔区进行碱基序列测定,以期建立从分子水平对中草药种子进行鉴定的一种新方法。方法:提取当归、大黄种子中核DNA,利用特异性引物对其rRNA基因内转录间隔区进行套式PCR扩增,并将扩增产物进行碱基序列测定。结果:经琼脂糖凝胶电泳证实:以上述方法可获得当归、大黄种子DNA中rRNA基因内转录间隔区PCR扩增产物;并经测序后得到了当归、大黄种子rRNA基因内转录间隔区的碱基序列,且具有明显的差异和可对比性。结论:不同植物性中药材种子rRNA基因内转录间隔区碱基序列可做为从分子水平进行鉴定的标记。 相似文献