首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   3166篇
  免费   215篇
  国内免费   79篇
耳鼻咽喉   10篇
儿科学   191篇
妇产科学   64篇
基础医学   354篇
口腔科学   85篇
临床医学   346篇
内科学   735篇
皮肤病学   79篇
神经病学   289篇
特种医学   428篇
外科学   253篇
综合类   52篇
预防医学   165篇
眼科学   25篇
药学   174篇
  2篇
中国医学   1篇
肿瘤学   207篇
  2022年   19篇
  2021年   27篇
  2020年   24篇
  2019年   41篇
  2018年   53篇
  2017年   38篇
  2016年   53篇
  2015年   67篇
  2014年   96篇
  2013年   91篇
  2012年   90篇
  2011年   101篇
  2010年   119篇
  2009年   118篇
  2008年   104篇
  2007年   174篇
  2006年   108篇
  2005年   96篇
  2004年   68篇
  2003年   66篇
  2002年   61篇
  2001年   55篇
  2000年   45篇
  1999年   60篇
  1998年   147篇
  1997年   160篇
  1996年   139篇
  1995年   119篇
  1994年   120篇
  1993年   104篇
  1992年   43篇
  1991年   47篇
  1990年   52篇
  1989年   68篇
  1988年   63篇
  1987年   62篇
  1986年   63篇
  1985年   58篇
  1984年   38篇
  1983年   23篇
  1982年   31篇
  1981年   41篇
  1980年   35篇
  1979年   15篇
  1978年   18篇
  1977年   23篇
  1976年   33篇
  1975年   22篇
  1974年   12篇
  1969年   12篇
排序方式: 共有3460条查询结果,搜索用时 0 毫秒
141.
142.
Mushroom worker's lung disease   总被引:1,自引:0,他引:1  
Stolz  JL; Arger  PH; Benson  JM 《Radiology》1976,119(1):61
  相似文献   
143.
144.
145.
A method is described for the isolation of pure, chemically intact sheaths of blood microfilariae of Litomosoides carinii. Microfilariae were isolated according to standard techniques. Exsheathment was performed by freezing-thawingshaking procedures, repeated 5–10 times, i.e., larvae were frozen in liquid nitrogen, thawed at room temperature, and shaken vigorously for 5 s. Exsheathment rates were about 50%. Sheaths were separated from ensheathed and exsheathed microfilariae and microfilariae fragments by filtration through a polycarbonate filter (2 m pore size). The achievable yield (about 15% of the sheaths of a batch of microfilariae) was approximately 1 g of sheaths per 106 microfilariae.Supported by the Deutsche Forschungsgemeinschaft  相似文献   
146.
Femoral vein occlusion is not a common complication even after repeated hernia repair. We describe a case of a 14-year-old boy with a visible and soft, yet irreducible, mass below the inguinal ligament after 3 previous inguinal hernia repairs and heart catheterization in infancy. Further examination showed dilated venous collaterals, bypassing an occluded common femoral vein via the testicular sheaths and across the pelvic floor. We discuss etiology, diagnostic pitfalls, therapeutic options, and possible future complications, with a literature review.  相似文献   
147.
RATIONALE: Hip fractures can be separated into cervical and trochanteric fractures. Trochanteric fractures have been associated with up to twice the short-term mortality of cervical fractures in the elderly. There is also evidence suggesting that the mechanisms are different. Evidence from the literature remains limited on the predictive power of bone mineral density (BMD) and quantitative ultrasounds (QUS) for both types of hip fractures. METHODS: 5703 elderly women aged 75 years or more, who were recruited from the voting lists in the EPIDOS study, and had baseline calcaneal ultrasounds (QUS) and DXA measurements at the hip and the whole body, were analyzed in this paper. Among those, 192 hip fractures occurred during an average follow-up of 4 years, 108 cervical and 84 trochanteric fractures. RESULTS: Femoral neck, trochanteric and whole body BMD were able to predict trochanteric hip fracture (RR's and 95% CI were, respectively, 3.2 (2.4-4.2); 4.8 (3.5-6.6); and 2.8 (2.2-3.6)) more accurately than cervical fractures (respectively, 2.1 (1.7-2.7); 2.3 (1.8-3.0); 1.2 (1.0-1.6)). All ultrasound parameters, SOS, BUA, and stiffness index (SI) were significant predictors of trochanteric (RR's respectively 3.0 (2.2-4.1), 2.5(2.0-3.1), and 3.5(2.6-4.7)) but not cervical fractures. After adjustment for femoral neck or trochanteric BMD ultrasound parameters were still significant predictors of trochanteric fracture, and stiffness tended to be a better predictor of trochanteric fractures than either BUA or SOS with a relative risk of 2.25 (1.6-3.1). CONCLUSIONS: A significant decrease of all bone measurements, BMD and QUS, was highly predictive of trochanteric fractures, whereas a decrease of femoral neck and trochanteric BMD were only associated with a slight increase in cervical fracture risk and a low total body BMD or QUS parameters were not significant predictors of cervical fractures. In women who sustained a hip fracture, the decrease of BMD and QUS values increases the risk of trochanteric fracture as compared to cervical fracture. Trochanteric fractures were mostly a consequence of a generalized low BMD and QUS, whereas other parameters might be involved in cervical fractures.  相似文献   
148.
149.
Neurodegeneration following inflammatory injury is considered to be a pathological correlate of irreversible disability in patients with multiple sclerosis. The availability of neurotrophins could influence the probability or rate of disease progression and the time of onset. The BDNF-Val66Met-polymorphism leads to altered intracellular transport and secretion of BDNF, and is thus a logical candidate for a gene that influences susceptibility and, more specifically, the clinical course of multiple sclerosis. In order to test this hypothesis we genotyped the polymorphism in 951 UK multiple sclerosis trio families, but found no evidence for association before (p=0.63) or after stratification for clinical course (p=0.73).  相似文献   
150.
The molecular messenger nitric oxide (NO) not only serves a number of physiologic functions, but is also involved in the pathophysiology of neurodegeneration. It is produced by the nitric oxide synthase (NOS) isoenzymes. One of the many players regulating NOS activity is the Protein Inhibitor of NOS, PIN. To gain further insight into the mechanisms of NOS regulation and NO-mediated cell death after nerve trauma, we examined PIN expression in a standard model of lesion-induced neurodegeneration, the rat optic nerve transsection model. In both the axotomized retinae and the control retinae PIN expression was predominantly observed in the retinal ganglion cell layer. Optic nerve lesion did neither change the amount of PIN mRNA, as determined by in situ hybridization and real-time RT-PCR, nor did it change the amount of PIN as determined by immunohistochemistry and Western blot analysis. These results suggest that in our model, NOS activity is not regulated by altered PIN levels, which contributes to our understanding of apoptotic mechanisms in injured neurons.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号