全文获取类型
收费全文 | 1364篇 |
免费 | 68篇 |
国内免费 | 9篇 |
专业分类
耳鼻咽喉 | 13篇 |
儿科学 | 75篇 |
妇产科学 | 17篇 |
基础医学 | 178篇 |
口腔科学 | 71篇 |
临床医学 | 105篇 |
内科学 | 256篇 |
皮肤病学 | 7篇 |
神经病学 | 44篇 |
特种医学 | 137篇 |
外科学 | 182篇 |
综合类 | 43篇 |
一般理论 | 2篇 |
预防医学 | 55篇 |
眼科学 | 78篇 |
药学 | 96篇 |
1篇 | |
中国医学 | 6篇 |
肿瘤学 | 75篇 |
出版年
2023年 | 10篇 |
2022年 | 22篇 |
2021年 | 81篇 |
2020年 | 56篇 |
2019年 | 53篇 |
2018年 | 59篇 |
2017年 | 44篇 |
2016年 | 49篇 |
2015年 | 52篇 |
2014年 | 50篇 |
2013年 | 103篇 |
2012年 | 114篇 |
2011年 | 88篇 |
2010年 | 64篇 |
2009年 | 36篇 |
2008年 | 58篇 |
2007年 | 54篇 |
2006年 | 65篇 |
2005年 | 47篇 |
2004年 | 49篇 |
2003年 | 32篇 |
2002年 | 14篇 |
2001年 | 3篇 |
2000年 | 3篇 |
1999年 | 5篇 |
1998年 | 23篇 |
1997年 | 24篇 |
1996年 | 18篇 |
1995年 | 19篇 |
1994年 | 15篇 |
1993年 | 10篇 |
1991年 | 5篇 |
1990年 | 10篇 |
1989年 | 13篇 |
1988年 | 5篇 |
1987年 | 4篇 |
1986年 | 8篇 |
1985年 | 6篇 |
1984年 | 7篇 |
1982年 | 4篇 |
1981年 | 7篇 |
1980年 | 10篇 |
1978年 | 6篇 |
1977年 | 5篇 |
1976年 | 6篇 |
1975年 | 4篇 |
1961年 | 3篇 |
1958年 | 2篇 |
1954年 | 2篇 |
1953年 | 2篇 |
排序方式: 共有1441条查询结果,搜索用时 78 毫秒
1.
2.
3.
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
4.
5.
Michael N. Tzermiadianos Avinash G. Patwardhan 《中华骨科杂志》2007,27(9):718-720
介绍:骨质疏松的椎体其强度和刚度都会降低,这就意味着椎体的破坏负荷与抵抗压缩变形的能力均降低。强度和刚度的降低量与骨质疏松的严重程度呈正比。因为这些特性与骨小梁的密度有很大的相关性。椎体压缩性骨折后强度和刚度值与骨折前相比进一步降低。其临床结果是:(1)骨质疏松导致椎体强度降低,继而导致最初的骨质疏松性骨折,骨折后的椎体有进一步压缩性骨折的倾向。[第一段] 相似文献
6.
Androgen receptor YAC transgenic mice carrying CAG 45 alleles show trinucleotide repeat instability 总被引:1,自引:15,他引:1
La Spada AR; Peterson KR; Meadows SA; McClain ME; Jeng G; Chmelar RS; Haugen HA; Chen K; Singer MJ; Moore D; Trask BJ; Fischbeck KH; Clegg CH; McKnight GS 《Human molecular genetics》1998,7(6):959-967
X-linked spinal and bulbar muscular atrophy (SBMA) is caused by a CAG
repeat expansion in the first exon of the androgen receptor (AR) gene.
Disease-associated alleles (37-66 CAGs) change in length when transmitted
from parents to offspring, with a significantly greater tendency to shift
size when inherited paternally. As transgenic mice carrying human AR cDNAs
with 45 and 66 CAG repeats do not display repeat instability, we attempted
to model trinucleotide repeat instability by generating transgenic mice
with yeast artificial chromosomes (YACs) carrying AR CAG repeat expansions
in their genomic context. Studies of independent lines of AR YAC transgenic
mice with CAG 45 alleles reveal intergenerational instability at an overall
rate of approximately 10%. We also find that the 45 CAG repeat tracts are
significantly more unstable with maternal transmission and as the
transmitting mother ages. Of all the CAG/CTG repeat transgenic mice
produced to date the AR YAC CAG 45 mice are unstable with the smallest
trinucleotide repeat mutations, suggesting that the length threshold for
repeat instability in the mouse may be lowered by including the appropriate
flanking human DNA sequences. By sequence-tagged site content analysis and
long range mapping we determined that one unstable transgenic line has
integrated an approximately 70 kb segment of the AR locus due to
fragmentation of the AR YAC. Identification of the cis - acting elements
that permit CAG tract instability and the trans -acting factors that
modulate repeat instability in the AR YAC CAG 45 mice may provide insights
into the molecular basis of trinucleotide repeat instability in humans.
相似文献
7.
In a child with some features of Turner's syndrome, gonosomal mosaicism with an isodicentric nonfluorescent (idic)Y chromosome was detected (mos 45,X/47,X,idic(Y)(q11),idic(Y)(11)/46,X,idic(Y)(q11)). Histopathological examination showed streak gonads with some evidence of ovarian stroma and no sign of gonadoblastoma. Polymerase chain reaction (PCR) analysis in blood lymphocytes and gonadal tissues using primers of seven loci along the Y chromosome, including the sex determined region (SRY), azoospermia factor region (AZF) and the deleted in azoospermia ( DAZ ) gene was positive for all loci tested, confirming the isodicentric character of the Y chromosome and indicating the presence of the AZF region. It is remarkable that the existence of spermatogenesis controlling genes does not play an important role in gonadal development and differentiation in a phenotypic female with some Turner stigmata. The data presented here are briefly discussed with previously-described patients. 相似文献
8.
Blair R. Peters Amanda M. Martin Brett F. Memauri Hardy W. Bock Robert B. Turner Kenneth A. Murray Avinash Islur 《Hand (New York, N.Y.)》2021,16(3):310
Background: Endoscopic carpal tunnel release (ECTR) has purported advantages over open release such as reduced intraoperative dissection and trauma and more rapid recovery. Endoscopic carpal tunnel release has been shown to have comparable outcomes to open release, but open release is considered easier and safer to perform. Previous studies have demonstrated an increase in carpal tunnel volume, regardless of the technique used. However, the mechanism by which this volumetric increase occurs has been debated. Our study will determine through magnetic resonance imaging (MRI) analysis the morphologic changes that occur in both open carpal tunnel release (OCTR) and ECTR, thereby clarifying any morphologic differences that occur as a result of the 2 operative techniques. We hypothesize that there will be no morphologic differences between the 2 techniques. Methods: This was a prospective study to compare the postoperative anatomy of both techniques with MRI. Nineteen patients with clinical and nerve conduction study–confirmed carpal tunnel syndrome underwent either open or endoscopic release. Magnetic resonance imaging was performed preoperatively and 6 months postoperatively in all patients to examine the volume of the carpal tunnel, transverse distance, anteroposterior (AP) distance, divergence of tendons, and Guyon’s canal transverse and AP distance. Results: There was no significant difference in the postoperative morphology of the carpal tunnel and median nerve between OCTR and ECTR at 6-month follow-up on MRI. Conclusion: We conclude that there are no morphologic differences in OCTR and ECTR. It is an increase in the AP dimension that appears to be responsible for the increase in the volume of the carpal tunnel. 相似文献
9.
Renal transplant (RT) is now a therapy of choice for end stage renal disease (ESRD). The Nephrology Unit, Asvini started functioning in Dec 90 and to date 1298 sittings of hemodialysis have been given to 45 patients. Of these, 35 were in ESRD and 11 patients underwent renal transplantation at this hospital during the period Jan 91 – Dec 93. One patient expired after 18 months of transplantation due to infection. Early experience in screening patients for RT, use of immunosuppression, management of rejection episodes and protocol are presented with special emphasis on its relevance to the Armed Forces.KEY WORDS: Transplantation, Renal Failure, Immunosuppression, Rejection 相似文献
10.