全文获取类型
收费全文 | 9507篇 |
免费 | 497篇 |
国内免费 | 27篇 |
专业分类
耳鼻咽喉 | 120篇 |
儿科学 | 801篇 |
妇产科学 | 381篇 |
基础医学 | 1045篇 |
口腔科学 | 200篇 |
临床医学 | 491篇 |
内科学 | 1748篇 |
皮肤病学 | 154篇 |
神经病学 | 336篇 |
特种医学 | 242篇 |
外科学 | 1872篇 |
综合类 | 282篇 |
一般理论 | 4篇 |
预防医学 | 369篇 |
眼科学 | 640篇 |
药学 | 515篇 |
1篇 | |
中国医学 | 27篇 |
肿瘤学 | 803篇 |
出版年
2023年 | 73篇 |
2022年 | 170篇 |
2021年 | 340篇 |
2020年 | 183篇 |
2019年 | 232篇 |
2018年 | 319篇 |
2017年 | 224篇 |
2016年 | 278篇 |
2015年 | 248篇 |
2014年 | 347篇 |
2013年 | 440篇 |
2012年 | 622篇 |
2011年 | 620篇 |
2010年 | 396篇 |
2009年 | 283篇 |
2008年 | 482篇 |
2007年 | 522篇 |
2006年 | 497篇 |
2005年 | 400篇 |
2004年 | 327篇 |
2003年 | 315篇 |
2002年 | 256篇 |
2001年 | 220篇 |
2000年 | 217篇 |
1999年 | 196篇 |
1998年 | 92篇 |
1997年 | 60篇 |
1996年 | 48篇 |
1995年 | 48篇 |
1992年 | 96篇 |
1991年 | 96篇 |
1990年 | 75篇 |
1989年 | 72篇 |
1988年 | 71篇 |
1987年 | 74篇 |
1986年 | 81篇 |
1985年 | 105篇 |
1984年 | 56篇 |
1983年 | 57篇 |
1982年 | 40篇 |
1981年 | 37篇 |
1980年 | 36篇 |
1979年 | 81篇 |
1978年 | 46篇 |
1977年 | 47篇 |
1976年 | 42篇 |
1975年 | 35篇 |
1974年 | 42篇 |
1973年 | 48篇 |
1972年 | 46篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
21.
22.
V K Srivastava G Palit A K Agarwal K Shanker 《Pharmacological research communications》1987,19(9):617-628
Sixteen new compounds 2-methylamino substituted phenyl-3-substituted anilino 4 (3H) quinazolinones (3-18) were prepared. All the compounds were evaluated for their antiparkinsonian activity and compared with bromocriptine. Compounds 10,15 and 18 showed better activity. These compounds also bind with the dopamine receptors in striatal membrane preparations of rat brain. 相似文献
23.
24.
Effect of compressive follower preload on the flexion-extension response of the human lumbar spine. 总被引:5,自引:0,他引:5
Avinash G Patwardhan Robert M Havey Gerard Carandang James Simonds Leonard I Voronov Alexander J Ghanayem Kevin P Meade Thomas M Gavin Odysseas Paxinos 《Journal of orthopaedic research》2003,21(3):540-546
Traditional experimental methods are unable to study the kinematics of whole lumbar spine specimens under physiologic compressive preloads because the spine without active musculature buckles under just 120 N of vertical load. However, the lumbar spine can support a compressive load of physiologic magnitude (up to 1200 N) without collapsing if the load is applied along a follower load path. This study tested the hypothesis that the load-displacement response of the lumbar spine in flexion-extension is affected by the magnitude of the follower preload and the follower preload path. Twenty-one fresh human cadaveric lumbar spines were tested in flexion-extension under increasing compressive follower preload applied along two distinctly different optimized preload paths. The first (neutral) preload path was considered optimum if the specimen underwent the least angular change in its lordosis when the full range of preload (0-1200 N) was applied in its neutral posture. The second (flexed) preload path was optimized for an intermediate specimen posture between neutral and full flexion. A twofold increase in flexion stiffness occurred around the neutral posture as the preload was increased from 0 to 1200 N. The preload magnitude (400 N and larger) significantly affected the range of motion (ROM), with a 25% decrease at 1200 N preload applied along the neutral path. When the preload was applied along a path optimized for an intermediate forward-flexed posture, only a 15% decrease in ROM occurred at 1200 N. The results demonstrate that whole lumbar spine specimens can be subjected to compressive follower preloads of in vivo magnitudes while allowing physiologic mobility under flexion-extension moments. The optimized follower preload provides a method to simulate the resultant vector of the muscles that allow the spine to support physiologic compressive loads induced during flexion-extension activities. 相似文献
25.
Further evidence supporting a cause and effect relationship between blood transfusion and earlier cancer recurrence. 总被引:12,自引:0,他引:12 下载免费PDF全文
Studies of associations between perioperative blood transfusions and later recurrence of solid tumors have yielded conflicting results. A previous analysis of transfused patients suggested that recurrence was associated with transfusion of whole blood as opposed to red blood cell concentrates. Additional analyses were performed on patients with cancers of the colon, rectum, cervix, and prostate to determine if patients receiving whole blood, red blood cells only, or no transfusions had differing outcomes. Patients receiving 1 unit or more of whole blood had uniformly poor outcomes compared with nontransfused patients (p less than 0.001). In contrast, patients receiving only red blood cells had progressively worse recurrence and death rates with increasing numbers of transfusion, suggesting the presence of a dose-effect relationship. Employing multivariate techniques, blood transfusion of less than or equal to 3 units that included any whole blood were independently and significantly associated with earlier recurrence (p = 0.003) and death due to cancer (p = 0.02). Transfusions of less than or equal to 3 units of blood comprised solely of red blood cell concentrates were associated with no greater risk of recurrence than that seen in patients receiving no transfusion (p = 0.50). These results provide a potential explanation for the disparate results reported in studies of blood transfusion and cancer outcome. The marked difference in outcome seen between patients receiving a few units of red blood cells and comparable patients receiving even one unit of whole blood are consistent with the hypothesis that transfusion of stored blood plasma causes earlier tumor recurrence in some instances. Strategies for reducing these risks might include avoidance of whole blood transfusions when only 1-3 units are required, more conservative transfusion practice, use of autologous blood transfusions, and perhaps, use of red blood cells washed free of plasma and white cell debris. Clinical trials to test these hypotheses are urgently needed. 相似文献
26.
Hip arthroplasty is a common orthopaedic procedure with proven long-term success and reliable results. A wide range of associated conditions may affect the outcome of the arthroplasty and the surgeon has to keep these in mind when planning the surgery. In this article, such situations are discussed and recommendations are drawn from the evidence available in literature. 相似文献
27.
Praloy Chakraborty P Shakuja A Kundra Anil Jain Shivendra Singh S Anuradha Anil Agarwal Premashish Kar 《Tropical gastroenterology》2004,25(4):170-171
A 14-year-old male presented with abdominal pain, diarrhoea and a sensation of something prolapsing through the anus during defecation, and was found to have diffuse colonic polyposis. There was no evidence of mucocutaneous hyperpigmentation and family history was negative, suggesting a diagnosis of non-familial juvenile polyposis. Histological analysis of multiple endoscopic biopsies showed features typical of juvenile or retention type (hamartomatous) lesions: dilated cystic glands lined by mucocus-secreting epithelium and prominent, inflamed and congested lamina propria. However, admixed with these features, focal areas of atypical adenomatous changes were recognized. Even the intervening normal-looking colonic mucosa showed some dysplastic changes. These findings indicate that hamartomatous and atypical adenomatous epithelial changes can co exist in non-familial juvenile polyposis and the latter may confer a risk of malignant transformation in this otherwise non-neoplastic disease. 相似文献
28.
29.
U N Verma R R Singh R Misra S Naik S S Agarwal 《Annals of the rheumatic diseases》1992,51(10):1159-1161
The case is described of a patient with scleromyxoedema with features typical of systemic sclerosis. The features were so characteristic that the disease was misdiagnosed as systemic sclerosis. A brief review of the association of the two diseases is given. 相似文献
30.
A. Sethi I. Singh A. K. Agarwal D. Sareen 《Indian journal of otolaryngology and head and neck surgery》2005,57(4):283-286
The prognostic significance of the size of mastoid air cell system in the results of myringoplasty has been a matter of debate. Fifty ears with dry central perforation following C.S.O.M. were investigated. The size of mastoid air cell system was determined with planimetry of the X-ray picture and eustachian tube function was assessed using flourescein dye and nasal endoscopy. Myringoplasty was performed in all the 50 ears and postoperative results in terms of graft take up and hearing gain were assessed. The correlation between the size of mastoid air cell system, results of myringoplasty and tubal function has been discussed. The results show no correlation between the size of mastoid air cell system, postoperative results of myringoplasty and eustachian tube function. 相似文献