全文获取类型
收费全文 | 770篇 |
免费 | 40篇 |
国内免费 | 32篇 |
专业分类
耳鼻咽喉 | 1篇 |
儿科学 | 15篇 |
妇产科学 | 6篇 |
基础医学 | 113篇 |
口腔科学 | 15篇 |
临床医学 | 66篇 |
内科学 | 145篇 |
皮肤病学 | 15篇 |
神经病学 | 15篇 |
特种医学 | 134篇 |
外科学 | 69篇 |
综合类 | 86篇 |
预防医学 | 30篇 |
眼科学 | 9篇 |
药学 | 70篇 |
肿瘤学 | 53篇 |
出版年
2023年 | 3篇 |
2022年 | 2篇 |
2021年 | 22篇 |
2020年 | 6篇 |
2019年 | 16篇 |
2018年 | 10篇 |
2017年 | 8篇 |
2016年 | 12篇 |
2015年 | 10篇 |
2014年 | 18篇 |
2013年 | 22篇 |
2012年 | 32篇 |
2011年 | 21篇 |
2010年 | 25篇 |
2009年 | 24篇 |
2008年 | 29篇 |
2007年 | 44篇 |
2006年 | 32篇 |
2005年 | 28篇 |
2004年 | 12篇 |
2003年 | 21篇 |
2002年 | 19篇 |
2001年 | 25篇 |
2000年 | 13篇 |
1999年 | 14篇 |
1998年 | 40篇 |
1997年 | 24篇 |
1996年 | 23篇 |
1995年 | 20篇 |
1994年 | 19篇 |
1993年 | 16篇 |
1992年 | 8篇 |
1991年 | 17篇 |
1990年 | 12篇 |
1989年 | 27篇 |
1988年 | 25篇 |
1987年 | 21篇 |
1986年 | 22篇 |
1985年 | 13篇 |
1984年 | 14篇 |
1983年 | 14篇 |
1982年 | 7篇 |
1981年 | 13篇 |
1980年 | 14篇 |
1978年 | 4篇 |
1977年 | 3篇 |
1976年 | 3篇 |
1975年 | 7篇 |
1974年 | 2篇 |
1972年 | 3篇 |
排序方式: 共有842条查询结果,搜索用时 15 毫秒
1.
目的由于卒中风险随着狭窄严重程度的增加而升高,因此认为颈内动脉(ICA)接近闭塞患者的卒中风险很高。在现有的随机试验中,还没有专门针对这种情况进行探讨,因此其处理尚存在争汶。方法:对相关文献进行系统评价。结果:对ICA接近闭塞患者的处理还存在争议:一些学者支持进行干预,而另一些学者则认为存在风险或没有益处而反对进行干预。在ICA接近闭塞的有症状患者中进行一项比较外科治疗与最佳内科治疗的多中心前瞻性随机试验似乎非常困难,因为这类研究需要大量的患者。尽管如此,基于目前的证据,似乎很难拒绝手术治疗。结论:由于目前对ICA接近闭塞患者的最佳处理方案仍存在着争议,因此需要前瞻性观察性研究以证实其在有症状和无症状人群中的患病率以及相关的卒中风险。基于目前的证据,大多数医疗中心选择手术治疗,但它相对干内科治疗的特粱尚右待证章. 相似文献
2.
3.
4.
Rupture of the distal biceps tendon: evaluation with MR imaging 总被引:2,自引:0,他引:2
5.
In order to demonstrate a possible complement activation during early bronchospastic reaction in asthma, we have measured plasmatic C3d (a split product of C3) and the C3d/C3 index, both of which are sensitive indices of complement activation. Twenty-nine allergenic bronchial challenge tests were accomplished, with an absence of response in six cases, an early reaction in sixteen cases and a dual reaction in seven cases. Changes in plasmatic C3d or C3d/C3 five min after an early reaction, or five min after the last dose of allergen (in the six cases without bronchial response) were insignificant. However, complement activation in the lungs during asthmatic reaction cannot be completely excluded without studies using the bronchoalveolar technique. 相似文献
6.
C Balestra J Duchateau K Hainaut 《Electroencephalography and clinical neurophysiology》1992,85(1):46-52
The effects of fatigue on the electromyographic (EMG) reflex activities were compared during sustained voluntary contractions and contractions evoked by electrical stimulation (30 Hz) in the human first dorsal interosseus (FDI). Short latency (SL), medium latency (ML) and long latency (LL) reflex responses to a ramp-and-hold stretch of the muscle were recorded and analysed in 27 healthy subjects of both sexes. The amplitude of the reflex components was normalized as function of the amplitude of the surface action potential (SAP) recorded in response to the supramaximal stimulation of the motor nerve. The results indicate that for a similar reduction of force, SL and ML are significantly reduced after fatigue induced by voluntary contractions but they are not when the fatigue test is performed by electrical stimulation at the motor point. In voluntary fatigue experiments, the LL component showed no significant decrease below control values, but an enhancement was observed during electrically evoked contraction. This enhancement remained above control values for at least 15 min during the recovery period, whereas SL and ML decreases returned to control within 5 min after the fatigue tests. The electrical stimulation applied to the skin overlying the FDI at an intensity lower than the motor threshold did not affect SL and ML, but enhanced LL for about 15 min. On the contrary, the anaesthesia of the skin overlying the FDI induced a decrease in LL without significant change of SL and ML. It is concluded that muscle reflex fatigue is present during sustained voluntary contractions and decreases SL and ML responses to quick stretches.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
7.
8.
Patients with chronic pain constitute a major problem for the surgeon as the cause of their pain is often difficult to diagnose and is only rarely a well circumscribed lesion which is amenable to surgical or other treatment. We report a case of chronic pain due to a vascular leiomyoma beneath the deep fascia of the leg. Angioleiomyomas are rare tumours that are usually found in the subcutaneous tissue. 相似文献
9.
P. J. Griffiths J. J. Duchateau Y. Maeda J. D. Potter C. C. Ashley 《Pflügers Archiv : European journal of physiology》1990,415(5):554-565
Intact muscle fibres fromBalanus nubilus develop tensions of up to 600 kN sd m−2 during electrical stimulation. The rise of tension occurs with a half-time (177 ms at 12° C) about fivefold longer than that
of tetanised frog muscle at the same temperature. The response of myofibrillar bundles to a rapid stretch resembles that of
frog muscle but has a yo value (i.e. the size of an instantaneous release necessary to just discharge tension) which is ca. 2.5 times smaller, and
phase 2 of the tension transient (the “quick phase”) occurs at a rate comparable to that of frog muscle. In contrast, the
ATPase activity (0.018 mmoles · kg wet weight−1 · s−1) of this preparation and its maximum shortening velocity (0.15–0.16 muscle lengths · s−1) are both at least fivefold slower than frog muscle. These findings can be accounted for by a cross-bridge cycle in barnacle
muscle in which events prior and subsequent to the tension generating step(s) occur at a rate at least fivefold slower than
comparable steps in frog muscle, but the step(s) associated with tension development occur at similar rates in the two preparations.
Since the rate of mechanical relaxation in barnacle muscle is modified in the presence of intracellular calcium buffers and
by depolarisation-induced elevation of the free calcium during the relaxation phase, it is proposed that the time course of
relaxation is not determined exclusively by the kinetics of the cross-bridge cycle, but is also dependent on the free calcium
concentration during relaxation. 相似文献
10.
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