全文获取类型
收费全文 | 21499篇 |
免费 | 3753篇 |
国内免费 | 263篇 |
专业分类
耳鼻咽喉 | 767篇 |
儿科学 | 891篇 |
妇产科学 | 526篇 |
基础医学 | 1897篇 |
口腔科学 | 541篇 |
临床医学 | 2702篇 |
内科学 | 4945篇 |
皮肤病学 | 635篇 |
神经病学 | 2153篇 |
特种医学 | 898篇 |
外科学 | 5038篇 |
综合类 | 185篇 |
现状与发展 | 2篇 |
一般理论 | 3篇 |
预防医学 | 1547篇 |
眼科学 | 570篇 |
药学 | 554篇 |
中国医学 | 12篇 |
肿瘤学 | 1649篇 |
出版年
2023年 | 535篇 |
2022年 | 185篇 |
2021年 | 395篇 |
2020年 | 792篇 |
2019年 | 314篇 |
2018年 | 791篇 |
2017年 | 738篇 |
2016年 | 890篇 |
2015年 | 824篇 |
2014年 | 1162篇 |
2013年 | 1355篇 |
2012年 | 731篇 |
2011年 | 687篇 |
2010年 | 865篇 |
2009年 | 1063篇 |
2008年 | 736篇 |
2007年 | 576篇 |
2006年 | 669篇 |
2005年 | 619篇 |
2004年 | 544篇 |
2003年 | 461篇 |
2002年 | 475篇 |
2001年 | 537篇 |
2000年 | 460篇 |
1999年 | 474篇 |
1998年 | 374篇 |
1997年 | 385篇 |
1996年 | 428篇 |
1995年 | 391篇 |
1994年 | 263篇 |
1993年 | 210篇 |
1992年 | 415篇 |
1991年 | 403篇 |
1990年 | 354篇 |
1989年 | 424篇 |
1988年 | 375篇 |
1987年 | 361篇 |
1986年 | 354篇 |
1985年 | 339篇 |
1984年 | 260篇 |
1983年 | 262篇 |
1982年 | 197篇 |
1981年 | 174篇 |
1980年 | 170篇 |
1979年 | 250篇 |
1978年 | 238篇 |
1977年 | 193篇 |
1976年 | 194篇 |
1975年 | 185篇 |
1972年 | 181篇 |
排序方式: 共有10000条查询结果,搜索用时 390 毫秒
21.
Changing attentional demands in left hemispatial neglect. 总被引:1,自引:0,他引:1
R F Kaplan M Verfaellie M E Meadows L R Caplan M S Pessin L D DeWitt 《Archives of neurology》1991,48(12):1263-1266
Seven variations of a letter cancellation test were used to examine how varying attentional demands affect hemispatial neglect in patients with right hemisphere lesions. While the 14 targets always remained in the same location, the number of distractors (zero, nine, 28, or 82) as well as their complexity (one letter or nine different letters) were varied. The percentage of targets canceled in the left hemispace was linearly related to the number of distractors. There were no differences between the complexity conditions. In a second study, the same 14 targets were presented but the distractors (zero, 14, or 41) were all placed on the right. Increasing the number of distractors on the right increased neglect on both sides of the space. Taken together, these results suggest that, while the limited attentional resources of the left hemisphere are biased toward the right hemispace, the absence of contralateral attentional demands allows these resources to be directed ipsilaterally. 相似文献
22.
The following recommendations of the Neonatal Hemostasis Subcommittee of the Scientific and Standardization Committee of the ISTH for the management of neonatal immune thrombocytopenia were prepared by the working party on neonatal immune thrombocytopenia. Evaluation, diagnosis, and treatment of the mother and neonate with alloimmune and autoimmune thrombocytopenia are discussed and current recommendations provided. This document is likely to require frequent future revision(s). 相似文献
23.
Poverty and health. Prospective evidence from the Alameda County Study 总被引:52,自引:0,他引:52
To examine the reasons for the association between socioeconomic status and poor health, the authors examined the nine-year mortality experience of a random sample of residents aged 35 and over in Oakland, California. Residents of a federally designated poverty area experienced higher age-, race-, and sex-adjusted mortality over the follow-up period compared with residents of nonpoverty areas (relative risk = 1.71, 95 per cent confidence interval 1.20-2.44). This increased risk of death persisted when there was multivariate adjustment for baseline health status, race, income, employment status, access to medical care, health insurance coverage, smoking, alcohol consumption, physical activity, body mass index, sleep patterns, social isolation, marital status, depression, and personal uncertainty. These results support the hypothesis that properties of the sociophysical environment may be important contributors to the association between low socioeconomic status and excess mortality, and that this contribution is independent of individual behaviors. 相似文献
24.
Platelet antibodies in systemic lupus erythematosus 总被引:2,自引:0,他引:2
C. Kaplan P. Champeix D. Blanchard J. Y. Muller J. P. Cartron 《British journal of haematology》1987,67(1):89-93
In systemic lupus erythematosus (SLE), the precise cause of the thrombocytopenia is unknown. Since platelet associated IgG is increased in many patients, it has been suggested that the destruction of platelets might be dependent on specific antibodies. In nine patients with SLE, platelet associated immunoglobulins were found together with free serum antibody which bound to platelets from all normal subjects. Using an immunoblotting technique with membrane proteins from normal platelets incubated with patient sera, target antigens were localized on a band of mol wt 108,000 in two cases (B. and N.) and on a band of mol wt 66,000 in a third (M.). When the same technique was applied to autologous platelets of patient N., autoantibody binding to the protein of mol wt 108,000 was demonstrated. The antigenic determinants were not removed from the platelets by enzyme treatment or by disulphide bond reduction, and were localized in the cytoplasmic fraction of the platelets. 相似文献
25.
26.
27.
S Kursunoglu P Kaplan D Resnick D J Sartoris 《Journal of oral and maxillofacial surgery》1986,44(4):257-259
Ten temporomandibular joints, obtained from three asymptomatic patients and two cadavers, were examined by three-dimensional computed tomography. The osseous components of the condylar process of the mandible and the glenoid fossa of the temporal bone were well visualized. The meniscus was visualized in both the closed- and the open-mouthed positions. Advantages and disadvantages of the technique are discussed. 相似文献
28.
Michael C. Dalsing MD Melissa Kevorkian BS Beth Raper BA Craig Nixon MS Stephen G. Lalka MD Dolores F. Cikrit MD Joseph L. Unthank PhD Malcolm B. Herring MD 《Annals of vascular surgery》1989,3(2):127-133
This study evaluates the potential for endothelial seeding of a collagen-impregnated Dacron graft with or without surface modifiers (fibronectin, heparin) to attach and retain these cells during flow. Human umbilical endothelial cells were harvested, cultured, labeled with Indium111-oxine and seeded onto 30 mm X 4 mm diameter grafts. Six graft surfaces were studied: 1) a collagen-impregnated Dacron graft, HemashieldR (C); 2) C + fibronectin (C + F); 3) C + heparin (C + H); 4) C + F + H; 5) HytrelR + F (Hyt + F); and 6) Hyt + F + H. Radioactive loss determined the percentage attachment and then percentage retention of labeled inoculum after a one-hour in vitro perfusion. Scanning electron and light microscopy demonstrated the endothelium on the graft surface following perfusion. Fibronectin-coated grafts had a significantly higher percentage attachment than those without fibronectin (ANOVA, P less than 0.05). However, the percentage retention following perfusion was similar for all Dacron grafts and statistically inferior to the HytrelR grafts studied (ANOVA, P less than 0.05). SEM evaluation of the C + F + H graft surface was qualitatively the most impressive Dacron surface for seeding, yet was inferior to the HytrelR graft. We conclude that fibronectin benefits the initial attachment of endothelium to collagen-coated Dacron rivaling the HytrelR surface. Fibronectin does not improve percentage retention of the HemashieldR surface during perfusion, therefore, some of its initial benefit is lost. 相似文献
29.
Kenneth K. H. Chao BS Eric Cheung BS William B. Armstrong MD Brian J. F. Wong MD 《Otolaryngology--head and neck surgery》2002,126(6):593
Objective: The study goal was to compare the laser spot size created using reflective and refractive micromanipulators with a CO2 laser and to determine the sensitivity of spot size to laser power. Study Design and Setting: A CO2 laser and operating microscope (400-mm focal length) was coupled to either a reflective (Cassegrain-like) or refractive micromanipulator. Laser spot size was determined by measuring the region of ablation created by laser irradiation of wood (dry tongue depressors), exposed photographic film, and agar gel using optical micrometry. Laser power varied from 0.5 to 20 W with pulse durations of 0.1 and 0.5 second. Results: The reflective micromanipulator demonstrated overall smaller spot sizes for a given laser power and lower incremental change in spot size with increasing power. The reflective design demonstrated less sensitivity to increases in laser power. Conclusions: Micromanipulator optical design can result in significant differences in laser spot size. The reflective device used in this study demonstrated less sensitivity to increasing laser power. (Otolaryngol Head Neck Surg 2002;126:593-597.) 相似文献
30.