全文获取类型
收费全文 | 63251篇 |
免费 | 4664篇 |
国内免费 | 332篇 |
专业分类
耳鼻咽喉 | 643篇 |
儿科学 | 1603篇 |
妇产科学 | 1539篇 |
基础医学 | 7843篇 |
口腔科学 | 1537篇 |
临床医学 | 6357篇 |
内科学 | 14384篇 |
皮肤病学 | 809篇 |
神经病学 | 4998篇 |
特种医学 | 1916篇 |
外国民族医学 | 2篇 |
外科学 | 9744篇 |
综合类 | 1010篇 |
现状与发展 | 1篇 |
一般理论 | 103篇 |
预防医学 | 5254篇 |
眼科学 | 1860篇 |
药学 | 4429篇 |
中国医学 | 139篇 |
肿瘤学 | 4076篇 |
出版年
2023年 | 292篇 |
2022年 | 463篇 |
2021年 | 1155篇 |
2020年 | 724篇 |
2019年 | 1010篇 |
2018年 | 1244篇 |
2017年 | 847篇 |
2016年 | 968篇 |
2015年 | 1136篇 |
2014年 | 1775篇 |
2013年 | 2810篇 |
2012年 | 3775篇 |
2011年 | 4116篇 |
2010年 | 2346篇 |
2009年 | 2191篇 |
2008年 | 4008篇 |
2007年 | 4199篇 |
2006年 | 4020篇 |
2005年 | 4114篇 |
2004年 | 3843篇 |
2003年 | 3458篇 |
2002年 | 3417篇 |
2001年 | 730篇 |
2000年 | 623篇 |
1999年 | 722篇 |
1998年 | 741篇 |
1997年 | 609篇 |
1996年 | 492篇 |
1995年 | 491篇 |
1994年 | 466篇 |
1993年 | 440篇 |
1992年 | 531篇 |
1991年 | 509篇 |
1990年 | 417篇 |
1989年 | 439篇 |
1988年 | 396篇 |
1987年 | 373篇 |
1986年 | 355篇 |
1985年 | 419篇 |
1984年 | 432篇 |
1983年 | 394篇 |
1982年 | 528篇 |
1981年 | 443篇 |
1980年 | 485篇 |
1979年 | 301篇 |
1978年 | 321篇 |
1977年 | 321篇 |
1976年 | 261篇 |
1975年 | 287篇 |
1974年 | 246篇 |
排序方式: 共有10000条查询结果,搜索用时 46 毫秒
51.
George Dawson 《Journal of the National Medical Association》2005,97(10):1449-1450
52.
Xing Zheng Jiang Du Yunlong Xu Duanfang Liao George R. Pettit 《Medicinal chemistry research》2010,19(4):337-343
Two cancer cell growth inhibitory esters, 1,2-dipalmitoyl-3-glucosyl glycerol (1) and 1,6-dihydroxy-hexane-bis-palmitoyl ester (2), together with arachidic acid-2-hydroxy-glycerol ester, daucosterol, and oleanolic acid, were isolated from the roots of
Peucedanum ledebourielloides (Apiaceae family). The structures were determined by spectroscopic analyses. The esters 1 and 2 displayed significant activity against the SGC-7901, HT-29, and HL-60 cancer cell lines. 相似文献
53.
Background
Exercise has been recommended for improving global-well being in adults with fibromyalgia. However, no meta-analysis has determined the effects of exercise on global well-being using a single instrument and when analyzed separately according to intention-to-treat and per-protocol analyses. The purpose of this study was to fill that gap. 相似文献54.
Acetylcholinesterase inhibitors may improve myelin integrity. 总被引:2,自引:0,他引:2
George Bartzokis 《Neuropsychopharmacology》2007,62(4):294-301
Recent clinical trials have revealed that cholinergic treatments are efficacious in a wide spectrum of neuropsychiatric disorders that span the entire human lifespan and include disorders without cholinergic deficits. Furthermore, some clinical and epidemiological data suggest that cholinergic treatments have disease modifying/preventive effects. It is proposed that these observations can be usefully understood in a myelin-centered model of the human brain. The model proposes that the human brain's extensive myelination is the central evolutionary change that defines our uniqueness as a species and our unique vulnerability to highly prevalent neuropsychiatric disorders. Within the framework of this model the clinical, biochemical, and epidemiologic data can be reinterpreted to suggest that nonsynaptic effects of cholinergic treatments on the process of myelination and myelin repair contributes to their mechanism of action and especially to their disease modifying/preventive effects. The ability to test the model in human populations with safe and noninvasive imaging technologies makes it possible to undertake novel clinical trial efforts directed at primary prevention of some of the most prevalent and devastating of human disorders. 相似文献
55.
William P. Grant DPM Laurence G. Rubin DPM Guy R. Pupp DPM George Vito DPM Dwayne Jacobus DPM Erin A. Jerlin DPM Harry S. Tam DPM 《The Journal of foot and ankle surgery》2007,46(5):325-335
The purpose of this study was to assess 7 methods of fixation for a midtarsal osteotomy. Polyurethane foam models (N = 6) and cadaver specimens (N = 4-7) were used to examine the force generated by the different constructs of fixation. A midtarsal osteotomy was performed on each specimen in the test groups. The osteotomies were fixated either with 2 parallel 0.062-in Kirschner wires and 40-mm-long, 4-mm partially threaded, cancellous, cannulated titanium screws, an external ring fixator (frame), a frame with wires tensioned (tension), a frame with wires tensioned and compressed toward the osteotomy (tension and compression), a frame with tension, compression, and parallel Kirschner wires, or a frame with tension, compression, and two 4.0 cannulated parallel screws, respectively. Each model was fixated, and the force generated by the construct across the osteotomy was recorded via the use of pressure-sensitive film. Statistical analysis of the data in the polyurethane foam group determined that the use of frame with tension, compression, and two 4.0 parallel cannulated screws was statistically superior to 1) frame, 2) frame with tension, 3) 2 parallel Kirschner wires, 4) two 4.0 cannulated parallel screws, and 5) frame with tension and compression. A cadaver study determined that the frame with tension, compression, and 2 parallel Kirschner wires was statistically superior to 1) frame and 2) two parallel Kirschner wires. These findings suggest that there is a difference in the force generated by the type of fixation construct across a midtarsal osteotomy. 相似文献
56.
57.
Food-dependent exercise-induced anaphylaxis in childhood 总被引:1,自引:0,他引:1
George Du Toit 《Pediatric allergy and immunology》2007,18(5):455-463
The clinical syndrome of food-dependent exercise-induced anaphylaxis (FDEIA) is typified by the onset of anaphylaxis during (or soon after) exercise which was preceded by the ingestion of the causal food allergen/s. In FDEIA, both the food allergen/s and exercise are independently tolerated. FDEIA is an uncommon allergic condition in childhood, but nonetheless is an important differential diagnosis to be considered when faced by a child who has experienced exercise-associated anaphylaxis. The diagnosis of FDEIA is heavily dependent on the clinical history. Allergy tests may need to be performed to a broad panel of food and food additives. Modified exercise challenges (performed with and without prior ingestion of food) are frequently required as allergy test results frequently return low-positive results. A diagnosis of FDEIA facilitates the safe independent return to exercise and reintroduction of foods for patients who otherwise may unnecessarily avoid exercise and/or restrict their diet. The natural history of FDEIA is unknown; however, a safe return is usually achieved when the ingestion of the causal food allergen/s and exercise are separated. 相似文献
58.
Structure-activity relationship (SAR) between some natural flavonoids and ocular blood flow in the rabbit. 总被引:1,自引:0,他引:1
PURPOSE: Flavonoids with two to five hydroxy groups, with or without sugar, and/or methoxy groups were studied on their effects to affect ocular blood flow. METHODS: Colored microsphere technique was used to determine the ocular blood flow in rabbit eyes. RESULTS: Flavonoids with three free hydroxy (OH) groups seemed to produce the optimal effects in increasing ocular blood flow (naringenin and hesperitin, Pfalts and Bauer, Waterbury, CT). Whether the OH groups are below three (naringenin, hesperitin, Pfalts and Bauer, Waterbury, CT) or above four (Quercetin, Pfalts and Bauer, Waterbury, CT), they produced no effects on the ocular blood flow. When OH groups are four (rutin, Aldrich, Milwaukee, WI), it produced mixed effects on ocular blood flow. The attachment of rutinose and/or methoxy group in the structure did not affect the ocular blood flow one way or the other. CONCLUSION: The ocular blood flow is increased significantly by the number of OH group in the molecule, with three the best to increase the ocular blood flow. 相似文献
59.
George T Timberlake Manjo K Sharma Denise V Gobert Joseph H Maino 《Optometry and vision science》2003,80(11):772-777
PURPOSE: The Rodenstock scanning laser ophthalmoscope (SLO) is useful for mapping retinal function and for developing and evaluating visual rehabilitation methods. It is essential to know the visual angle subtended by stimuli in the SLO laser-beam raster and to accurately measure angular distances between objects in the final SLO image. To accomplish this, the angular extent of the SLO laser-beam raster must be calibrated. METHODS: We developed a simple method and apparatus for calibrating the raster and used it for repeated calibrations during a 3-month period. RESULTS: The laser-beam raster is quite stable in shape and size, but it is trapezoidally distorted in the vertical direction. Consequently, SLO images are distorted. CONCLUSIONS: Trapezoidal distortion of the SLO laser-beam raster can cause stimulus size to change as much as 10% from the top to the bottom of the raster. Measurements of fixed horizontal retinal landmark distances in SLO images can also vary as much as 10%. We developed a straightforward mathematical method for correcting distortion in SLO image measurements. 相似文献
60.