全文获取类型
收费全文 | 2109篇 |
免费 | 158篇 |
国内免费 | 4篇 |
专业分类
耳鼻咽喉 | 21篇 |
儿科学 | 67篇 |
妇产科学 | 32篇 |
基础医学 | 312篇 |
口腔科学 | 50篇 |
临床医学 | 229篇 |
内科学 | 441篇 |
皮肤病学 | 28篇 |
神经病学 | 142篇 |
特种医学 | 245篇 |
外科学 | 261篇 |
综合类 | 23篇 |
一般理论 | 2篇 |
预防医学 | 107篇 |
眼科学 | 67篇 |
药学 | 88篇 |
肿瘤学 | 156篇 |
出版年
2021年 | 24篇 |
2020年 | 23篇 |
2019年 | 26篇 |
2018年 | 32篇 |
2017年 | 25篇 |
2016年 | 41篇 |
2015年 | 49篇 |
2014年 | 42篇 |
2013年 | 83篇 |
2012年 | 94篇 |
2011年 | 75篇 |
2010年 | 71篇 |
2009年 | 53篇 |
2008年 | 88篇 |
2007年 | 100篇 |
2006年 | 89篇 |
2005年 | 90篇 |
2004年 | 88篇 |
2003年 | 85篇 |
2002年 | 65篇 |
2001年 | 87篇 |
2000年 | 62篇 |
1999年 | 69篇 |
1998年 | 54篇 |
1997年 | 45篇 |
1996年 | 37篇 |
1995年 | 31篇 |
1994年 | 31篇 |
1993年 | 24篇 |
1992年 | 38篇 |
1991年 | 39篇 |
1990年 | 39篇 |
1989年 | 31篇 |
1988年 | 23篇 |
1987年 | 21篇 |
1986年 | 29篇 |
1985年 | 27篇 |
1984年 | 22篇 |
1981年 | 12篇 |
1980年 | 13篇 |
1979年 | 27篇 |
1978年 | 16篇 |
1977年 | 12篇 |
1976年 | 17篇 |
1975年 | 23篇 |
1971年 | 13篇 |
1970年 | 13篇 |
1969年 | 18篇 |
1967年 | 13篇 |
1966年 | 13篇 |
排序方式: 共有2271条查询结果,搜索用时 15 毫秒
1.
S H Duda P E Huppert V Arndt M Wehrmann K K Haase C D Claussen 《Journal of vascular and interventional radiology : JVIR》1992,3(1):59-65
The suitability of a pulsed dye laser (504 nm) in experimental and clinical angioplasty was investigated. In an experimental study, the ablation thresholds were 3 J/cm2 +/- 8 (mean +/- standard deviation) for fibrofatty plaque and 25 J/cm2 for calcified tissues under saline. At a radiant exposure of 10 J/cm2 the etch rates were 1.7 microns per pulse +/- 0.3 for media, 2.8 microns/pulse +/- 0.4 for normal intima, and 3.9 microns/pulse +/- 1.1 for fibrofatty plaque (P less than .05). Pressure wave effects with a separation of tissue layers were predominantly localized at the internal elastic lamina. Thermal injury with vacuolations extended 15 microns +/- 6 into adjacent tissue. For clinical study, laser-assisted balloon angioplasty was performed in 10 patients (64 years +/- 14) with occlusions of peripheral arteries using a 9-F multifiber ring catheter. Lesion length ranged from 2 to 12 cm (mean, 7 cm). Laser angioplasty with an 80 mJ/pulse decreased the mean stenosis from 100% to 58% +/- 12% (P less than .005). The ankle-brachial index rose from a median of 0.48 to 0.88 (P less than .001). In 33% of patients, there were subintimal dissections after laser angioplasty. After a mean follow-up of 10.2 months, the overall clinical success was 70% with a primary patency of 78%. The over-the-wire approach with a pulsed dye laser may constitute a safe and feasible tool in laser angioplasty. 相似文献
2.
S Hanke H Hanke M Oberhoff K K Haase S Hassenstein E Betz K R Karsch 《Zeitschrift für Kardiologie》1991,80(6):404-411
To determine the time-course of morphological changes after excimer laser treatment of atherosclerotic carotid arteries, laser angioplasty was performed in 34 rabbits after production of an intimal plaque (13 +/- 6 cell layers, 30 +/- 9% stenosis) using electrical stimulations. The animals were sacrificed 3, 7, 14, 21, 28, and 42 days after laser treatment. A total or subtotal thrombotic occlusion was found in four cases. No perforation was observed, but in 10 animals histological examination evidenced a partial ablation of the medial layer with signs of local thrombus formation and local reduction of SMC in the media. In five animals a stenosis of more than 50% of luminal reduction was due to intimal proliferation of smooth muscle cells (SMC), as determined by a monoclonal antibody against alpha-actin. After the initial ablation, a continuous increase of intimal cell layers was found, from 7 +/- 6 cell layers (19 +/- 9% stenosis) at 7 days, to 28 +/- 5 cell layers (45 +/- 18% stenosis) at 28 days following excimer laser angioplasty (p less than 0.01). After 42 days no additional increase of intimal thickening occurred. Our data suggest that incidence and morphology is comparable to the proliferative response of SMC following conventional balloon angioplasty. 相似文献
3.
M L Ritchey K P Lally G M Haase S J Shochat P P Kelalis 《Journal of pediatric surgery》1992,27(5):612-615
Iatrogenic injury to the aorta or its major branches during nephrectomy for Wilms' tumor in children is rarely reported but may be more common than is currently acknowledged. We identified four patients with ligation of the superior mesenteric artery (SMA) that occurred during nephrectomy for nephroblastoma and another child in whom SMA thrombosis developed postoperatively. All of the tumors were on the left side. Interruption of the SMA was recognized intraoperatively in all four children, and primary repair was done. In three patients, appearance of the bowel remained normal before repair of the injury. Three of the arteries were repaired by primary reanastomosis, and one was joined with an interpositioned hypogastric artery graft. None of these patients had gastrointestinal complications postoperatively. In the fifth patient, SMA thrombosis developed after repair of an aortic tear during nephrectomy. This patient required subsequent small bowel resection for bowel infarction and died in the perioperative period. Every surgeon treating children with Wilms' tumor should be aware of the possibly distorted vascular anatomy and take precautions to avoid such a significant injury. Attempts at early ligation of the vessels may not be justified until the renal vasculature is clearly identified. 相似文献
4.
5.
Dao Yin Xie Stefan Hassenstein Martin Oberhoff Hartmut Hanke Andreas Baumbach Kristian Hohla Karl Konstantin Haase Karl Rüdiger Karsch 《Lasers in surgery and medicine》1993,13(6):618-624
A modified exeimer laser energy delivery system was used to irradiate 100 segments of normal and fibrous aorta in vitro. The laser beam was scanned into 8 fiber bundles consisting of 50 fibers each resulting in a reduction of the applied pulse energy. The total repetition rate was increased to 150 Hz in order to keep the repetition rate per fiber bundle close to 20 Hz and to minimize thermal injury. The results demonstrate that effective ablation (etch rate per 8 pulses > 2.0 μm) occurred at an energy fluency of 50 mJ/mm2 in both normal and fibrous aorta. Tissue damage (carbonization, tissue separation, fissures, cracks, and vacuolization) was in a range of 100 ± 28 to 152 ± 30 μm for normal aorta and in a range of 57 ± 35 to 110 ± 39 μm for fibrous aorta. We conclude that effective ablation of normal and fibrous human aorta can be achieved by the application of smooth excimer laser coronary angioplasty. This improvement of excimer laser technology may result in a reduction of shock wave- and cavitation-induced damage leading to a reduction of tissue injury. However, this awaits further in vitro and in vivo confirmation. © 1993 Wiley-Liss, Inc. 相似文献
6.
7.
A new method is presentd for the quantitative determination of regional blood volumes in vivo. It is based on rapid quantitative T1 mapping by Snapshot FLASH MRI combined with the injection of an intravascular MR contrast agent. Regional blood volumes in four different tissues of the rat (skeletal muscle, heart, liver, kidney) were determined in an In vivo experiment. 相似文献
8.
9.
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
10.
Summary Screening of a multi-copy vector-based yeast genomic library in haploid cells of wild-type Saccharomyces cerevisiae yielded transformants hyper-resistant to various chemical mutagens. Genetical analysis of the yeast insert DNAs revealed three genes SNG1, SNQ2, and SNQ3 that confer the phenotype hyper-resistance to MNNG, to 4-NQO and triaziquone, and to mutagens 4-NQO, MNNG, and triaziquone, respectively. Integration of the gene disruption-constructs into the haploid yeast genome yielded viable null-mutants with a mutagen-sensitive phenotype. Thus, copy number of these non-essential yeast genes determines the relative resistance to certain chemical mutagens, with zero copies yielding a phenotype of mutagen sensitivity and multiple copies one of mutagen hyper-resistance, respectively.Dedicated to Professor Dr. R. W. Kaplan on the occasion of his 80th birthday 相似文献