全文获取类型
收费全文 | 990篇 |
免费 | 47篇 |
国内免费 | 32篇 |
专业分类
儿科学 | 14篇 |
妇产科学 | 15篇 |
基础医学 | 96篇 |
口腔科学 | 18篇 |
临床医学 | 90篇 |
内科学 | 129篇 |
皮肤病学 | 128篇 |
神经病学 | 32篇 |
特种医学 | 133篇 |
外科学 | 138篇 |
综合类 | 93篇 |
预防医学 | 26篇 |
眼科学 | 4篇 |
药学 | 74篇 |
肿瘤学 | 79篇 |
出版年
2021年 | 11篇 |
2019年 | 10篇 |
2018年 | 5篇 |
2017年 | 11篇 |
2016年 | 13篇 |
2015年 | 19篇 |
2014年 | 16篇 |
2013年 | 26篇 |
2012年 | 34篇 |
2011年 | 31篇 |
2010年 | 19篇 |
2009年 | 25篇 |
2008年 | 39篇 |
2007年 | 52篇 |
2006年 | 37篇 |
2005年 | 36篇 |
2004年 | 27篇 |
2003年 | 24篇 |
2002年 | 28篇 |
2001年 | 27篇 |
2000年 | 33篇 |
1999年 | 33篇 |
1998年 | 44篇 |
1997年 | 31篇 |
1996年 | 23篇 |
1995年 | 22篇 |
1994年 | 20篇 |
1993年 | 16篇 |
1992年 | 9篇 |
1991年 | 23篇 |
1990年 | 15篇 |
1989年 | 17篇 |
1988年 | 23篇 |
1987年 | 23篇 |
1986年 | 25篇 |
1985年 | 18篇 |
1984年 | 20篇 |
1983年 | 16篇 |
1982年 | 15篇 |
1981年 | 16篇 |
1980年 | 14篇 |
1979年 | 15篇 |
1978年 | 16篇 |
1977年 | 5篇 |
1975年 | 15篇 |
1974年 | 5篇 |
1971年 | 4篇 |
1968年 | 4篇 |
1966年 | 6篇 |
1919年 | 4篇 |
排序方式: 共有1069条查询结果,搜索用时 15 毫秒
1.
A Nonell S Kerk F Lederbogen D Kopf B Hamann S Lewicka M Deuschle 《Experimental and clinical endocrinology & diabetes》2004,112(1):59-61
Preclinical research suggests adrenal beta-adrenergic receptors to be involved in the regulation of steroid synthesis. In a group of healthy male volunteers, we compared ACTH-induced cortisol and dehydroepiandrosterone (DHEA) secretion after pre-treatment with orciprenaline, propranolol or placebo. Neither baseline nor ACTH-induced steroid secretion differed between these conditions. Our data do not support the hypothesis that the adrenal beta-receptor plays a major role in steroid secretion in humans. 相似文献
2.
3.
G S Kopf H Laks H C Stansel W E Hellenbrand C S Kleinman N S Talner 《The Journal of thoracic and cardiovascular surgery》1990,100(5):662-70; discussion 670-1
The first superior vena cava-pulmonary artery shunt (Glenn shunt) in our series was performed in February 1958. From then through September 1988, 91 patients have undergone this procedure for a wide variety of congenital defects. We here report follow-up data available on all patients. Ages ranged from 2 days to 46 years (mean 6.8). Diagnoses were as follows: tricuspid atresia, 27; single ventricle, 22; tetralogy of Fallot, 14; D-transposition of the great arteries, ventricular septal defect, and pulmonary stenosis, 9; D-transposition, 5; Ebstein's anomaly, 4; pulmonary atresia + intact septum, 4; and others, 6. The hospital mortality rate was 7.7% (one death in the last 53 patients, 1.9%). Five deaths occurred in patients less than 6 months old. There were 20 late deaths (22%) with actuarial survival rates of 84% and 66% at 10 and 20 years, respectively. Pulmonary arteriovenous fistula formation was seen in 18 patients (19.7%), six of whom have undergone therapeutic embolization with improvement in saturation. The prevalence of pulmonary arteriovenous fistula increases with time after shunt. No long-term shunt thrombosis or stricture formation was seen. Fifty percent of shunts were still functioning at 20 years. Palliation was limited because of decrease in blood flow to the contralateral pulmonary artery, collaterals between the inferior and superior venae cavae, and pulmonary arteriovenous fistula formation. Improvement in saturation was obtained in eight otherwise inoperable patients by creation of a right axillary arteriovenous fistula up to 19 years after the Glenn shunt. Three patients had conversion of a Blalock-Taussig shunt to a Glenn shunt with improvement in congestive heart failure. Twenty-six patients have undergone a Fontan procedure with two deaths. Compared with the group having a Fontan procedure without a prior Glenn operation, there was no difference in early or late mortality. Thirty years after a Glenn shunt, the first patient in this series is working full time after having undergone a modified Fontan procedure in 1981. We conclude that the Glenn connection, usually with supplemental procedures to enhance oxygenation, has provided excellent physiologic palliation with low mortality up to 30 years with no late thrombosis or stricture formation. The incidence of pulmonary arteriovenous fistula increases with time and can be effectively treated with embolization. Physiologic repair after the Glenn shunt carries a low mortality. Although currently used infrequently, superior vena cava-pulmonary artery shunting remains a useful method of palliation in selected patients.(ABSTRACT TRUNCATED AT 400 WORDS) 相似文献
4.
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
5.
6.
7.
Rupture of the distal biceps tendon: evaluation with MR imaging 总被引:2,自引:0,他引:2
8.
9.
Manfred Kopf Suzanne Herren Michael V. Wiles Mark B. Pepys Marie H. Kosco-Vilbois 《The Journal of experimental medicine》1998,188(10):1895-1906
Mice rendered deficient for interleukin (IL) 6 by gene targeting were evaluated for their response to T cell–dependent antigens. Antigen-specific immunoglobulin (Ig)M levels were unaffected whereas all IgG isotypes showed varying degrees of alteration. Germinal center reactions occurred but remained physically smaller in comparison to those in the wild-type mice. This concurred with the observations that molecules involved in initial signaling events leading to germinal center formation were not altered (e.g., B7.2, CD40 and tumor necrosis factor R1). T cell priming was not impaired nor was a gross imbalance of T helper cell (Th) 1 versus Th2 cytokines observed. However, B7.1 molecules, absent from wild-type counterparts, were detected on germinal center B cells isolated from the deficient mice suggesting a modification of costimulatory signaling. A second alteration involved impaired de novo synthesis of C3 both in serum and germinal center cells from IL-6–deficient mice. Indeed, C3 provided an essential stimulatory signal for wild-type germinal center cells as both monoclonal antibodies that interrupted C3-CD21 interactions and sheep anti–mouse C3 antibodies caused a significant decrease in antigen-specific antibody production. In addition, germinal center cells isolated from C3–deficient mice produced a similar defect in isotype production. Low density cells with dendritic morphology were the local source of IL-6 and not the germinal center lymphocytes. Adding IL-6 in vitro to IL-6–deficient germinal center cells stimulated cell cycle progression and increased levels of antibody production. These findings reveal that the germinal center produces and uses molecules of the innate immune system, evolutionarily pirating them in order to optimally generate high affinity antibody responses. 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