全文获取类型
收费全文 | 577篇 |
免费 | 62篇 |
国内免费 | 66篇 |
专业分类
耳鼻咽喉 | 2篇 |
儿科学 | 42篇 |
妇产科学 | 3篇 |
基础医学 | 52篇 |
口腔科学 | 84篇 |
临床医学 | 84篇 |
内科学 | 132篇 |
皮肤病学 | 5篇 |
神经病学 | 20篇 |
特种医学 | 113篇 |
外科学 | 19篇 |
综合类 | 18篇 |
预防医学 | 68篇 |
药学 | 38篇 |
中国医学 | 3篇 |
肿瘤学 | 22篇 |
出版年
2022年 | 3篇 |
2021年 | 2篇 |
2020年 | 4篇 |
2019年 | 6篇 |
2018年 | 12篇 |
2017年 | 12篇 |
2016年 | 8篇 |
2015年 | 8篇 |
2014年 | 11篇 |
2013年 | 14篇 |
2012年 | 11篇 |
2011年 | 14篇 |
2010年 | 10篇 |
2009年 | 14篇 |
2008年 | 18篇 |
2007年 | 46篇 |
2006年 | 18篇 |
2005年 | 10篇 |
2004年 | 9篇 |
2003年 | 11篇 |
2002年 | 13篇 |
2001年 | 21篇 |
2000年 | 19篇 |
1999年 | 16篇 |
1998年 | 29篇 |
1997年 | 29篇 |
1996年 | 32篇 |
1995年 | 21篇 |
1994年 | 19篇 |
1993年 | 13篇 |
1992年 | 9篇 |
1991年 | 12篇 |
1990年 | 19篇 |
1989年 | 20篇 |
1988年 | 24篇 |
1987年 | 28篇 |
1986年 | 23篇 |
1985年 | 25篇 |
1984年 | 15篇 |
1983年 | 13篇 |
1982年 | 11篇 |
1981年 | 11篇 |
1980年 | 6篇 |
1979年 | 2篇 |
1978年 | 7篇 |
1977年 | 7篇 |
1976年 | 5篇 |
1975年 | 8篇 |
1965年 | 1篇 |
1964年 | 1篇 |
排序方式: 共有705条查询结果,搜索用时 0 毫秒
101.
Postinflammatory ossicular fixation is a common problem encountered by the otologic surgeon upon exploration because of conductive hearing loss in patients with chronic otitis media. These nonotosclerotic noncongenital lesions take three pathologic forms: fibrous tissue fixation (chronic adhesive otitis media), hyalinization of collagen (tympanosclerosis), and new bone formation (fibro-osseous sclerosis). Fibrous tissue fixation appears on CT as nonbony, noncalcific soft-tissue debris encasing some or all of the ossicular chain. Tympanosclerosis appears as unifocal or multifocal punctate or weblike calcifications in the middle ear cavity or on the tympanic membrane. This debris may be in direct apposition to the ossicular chain or may replace the suspensory ligaments in symptomatic patients. New bone formation has been identified only in the attic and is the least common manifestation. Thick bony webs or generalized bony encasement may be present at CT. More than 300 patients with the clinical diagnosis of chronic otitis media have been examined. This study encompasses 23 proved cases. 相似文献
102.
103.
Morbidity, disability, and long-term care of the elderly: implications for insurance financing 总被引:1,自引:0,他引:1
A scarcity of empirical information to specify appropriate provisions and base rates for coverage has hindered the development of long-term-care (LTC) insurance. Data from three nationally representative surveys on the prevalence of morbidity and functional limitations among the elderly population suggest that health status among older Americans is highly dynamic, especially at higher disability levels. The bioactuarial data may help insurers define potential markets of purchasers of policies, and identify the numbers of persons with disabilities severe enough to trigger use of benefits. If the accuracy of individual service predictions could be increased further, reserve requirements and overall costs to LTC insurance carriers might be reduced. 相似文献
104.
Tendon echogenicity: ex vivo study 总被引:2,自引:0,他引:2
Recent publications discussing the echogenicity of normal tendon have described it variously as hyperechoic or hypoechoic. Since the echogenicity of tendon has been used to define normality and abnormality, certain knowledge of the normal echogenicity of tendon is crucial. Fresh tendon and muscle from beef hock was scanned with sector- and linear-array-transducer imaging at multiple angles and distances. The echogenicity of tendon was found to be very angle-dependent, a characteristic known as anisotropy. Scanned perpendicular to its long axis with a linear-array transducer, tendon was significantly more echogenic than muscle. With a change in angle, echogenicity of tendon decreased relative to that of muscle (the echogenicity of muscle remained the same), becoming isoechoic at angles of 2 degrees -7 degrees and hypoechoic at greater angles. Tendon studied with a sector transducer exhibited varying echogenicity. If echogenicity is used as a diagnostic criterion, the angle of the interrogating ultrasound beam must be very specifically defined. 相似文献
105.
Indoleamine 2,3-dioxygenase (IDO), a flavin-dependent enzyme that catalyzes the conversion of tryptophan to kynurenine, is induced in peripheral blood mononuclear cells by interferon-gamma (IFN gamma). Interleukin-4 (IL-4) is a cytokine that modulates the functional properties of monocytes/macrophages, and we investigated the effects of IL-4 on IDO. We showed that IL-4 inhibited the induction of IDO mRNA and IDO activity by IFN gamma in human monocytes. The inhibitory effect was evident with as little as 2 U/mL of IL-4. These results provide the first evidence that a cytokine can provide a negative signal for IDO expression and that IL-4 can influence the catabolism of tryptophan. 相似文献
106.
107.
Dieli F; Asherson GL; Tomonari K; Sireci G; Caccamo N; Salerno A 《International immunology》1997,9(1):1-8
We have recently demonstrated a remarkable selection of in vitro
cultivated, TNP-specific polyclonal T cell lines for the expression of a
TCR beta chain encoded by the V beta 8.2 gene. The goal of the present
study was to analyse V alpha usage in V beta 8.2 T cells responsive to TNP,
using TNP-specific T cell lines derived from three common strains of mice,
as well as from V beta 8.2 transgenic mice. Results indicate that in vitro
TNP stimulation of T cells from TNP- immune mice results in significant
skewing of V alpha usage among responding V beta 8.2+ T cells, with
overexpression observed for V alpha 3.2 and V alpha 8. These results
indicate that V alpha expression influences recognition of TNP by T cells,
and suggest that the hapten TNP might be recognized like typical peptide
antigens by combinatorial TCR alpha and beta contact sites.
相似文献
108.
Rosen BR; Fleming DM; Kushner DC; Zaner KS; Buxton RB; Bennet WP; Wismer GL; Brady TJ 《Radiology》1988,169(3):799
109.
110.