全文获取类型
收费全文 | 274篇 |
免费 | 31篇 |
国内免费 | 7篇 |
专业分类
儿科学 | 5篇 |
妇产科学 | 2篇 |
基础医学 | 38篇 |
口腔科学 | 23篇 |
临床医学 | 34篇 |
内科学 | 66篇 |
皮肤病学 | 5篇 |
神经病学 | 12篇 |
特种医学 | 11篇 |
外科学 | 19篇 |
综合类 | 24篇 |
预防医学 | 6篇 |
眼科学 | 48篇 |
药学 | 9篇 |
肿瘤学 | 10篇 |
出版年
2023年 | 4篇 |
2022年 | 5篇 |
2021年 | 7篇 |
2020年 | 8篇 |
2019年 | 6篇 |
2018年 | 12篇 |
2017年 | 4篇 |
2016年 | 6篇 |
2015年 | 8篇 |
2014年 | 4篇 |
2013年 | 8篇 |
2012年 | 10篇 |
2011年 | 9篇 |
2010年 | 3篇 |
2009年 | 11篇 |
2008年 | 7篇 |
2007年 | 10篇 |
2006年 | 24篇 |
2005年 | 15篇 |
2004年 | 5篇 |
2003年 | 9篇 |
2002年 | 5篇 |
2001年 | 13篇 |
2000年 | 17篇 |
1999年 | 11篇 |
1998年 | 6篇 |
1997年 | 16篇 |
1996年 | 10篇 |
1995年 | 7篇 |
1994年 | 6篇 |
1993年 | 1篇 |
1992年 | 2篇 |
1991年 | 5篇 |
1990年 | 4篇 |
1989年 | 2篇 |
1988年 | 2篇 |
1987年 | 7篇 |
1986年 | 4篇 |
1985年 | 5篇 |
1984年 | 1篇 |
1981年 | 1篇 |
1980年 | 2篇 |
1979年 | 2篇 |
1977年 | 3篇 |
1976年 | 1篇 |
1975年 | 1篇 |
1972年 | 1篇 |
1966年 | 1篇 |
1963年 | 1篇 |
排序方式: 共有312条查询结果,搜索用时 140 毫秒
1.
George T Timberlake Manjo K Sharma Denise V Gobert Joseph H Maino 《Optometry and vision science》2003,80(11):772-777
PURPOSE: The Rodenstock scanning laser ophthalmoscope (SLO) is useful for mapping retinal function and for developing and evaluating visual rehabilitation methods. It is essential to know the visual angle subtended by stimuli in the SLO laser-beam raster and to accurately measure angular distances between objects in the final SLO image. To accomplish this, the angular extent of the SLO laser-beam raster must be calibrated. METHODS: We developed a simple method and apparatus for calibrating the raster and used it for repeated calibrations during a 3-month period. RESULTS: The laser-beam raster is quite stable in shape and size, but it is trapezoidally distorted in the vertical direction. Consequently, SLO images are distorted. CONCLUSIONS: Trapezoidal distortion of the SLO laser-beam raster can cause stimulus size to change as much as 10% from the top to the bottom of the raster. Measurements of fixed horizontal retinal landmark distances in SLO images can also vary as much as 10%. We developed a straightforward mathematical method for correcting distortion in SLO image measurements. 相似文献
2.
Regnier V; Meddeb M; Lecointre G; Richard F; Duverger A; Nguyen VC; Dutrillaux B; Bernheim A; Danglot G 《Human molecular genetics》1997,6(1):9-16
Type 1 neurofibromatosis (NF1) gene encodes for a member of the GTPase
activating protein family and is considered to be a tumor suppressor gene.
Its very high rate of de novo mutation in humans led us to study a specific
feature of this gene: the presence of numerous NF1-related sequences.
According to our results, the human genome contains at least 11 NF1-related
sequences, nine of which are scattered near centromeric sequences of seven
different chromosomes. These NF1-related sequences, whose extent is quite
varied according to loci, are unprocessed copies of the NF1 gene, and bear
numerous mutations. A phylogenetic analysis of the six largest sequences
indicates that they are all derived from a common ancestor, which would
have appeared 22-33 million years ago, and was subsequently duplicated
several times during hominoid evolution. The most recent duplication and
interchromosomal transposition occurred in the last million years
suggesting that the process could still be ongoing. Intriguing similarities
between the evolution of alpha- satellite DNA and NF1-related sequences
suggest the involvement of a common genetic mechanism for the generation
and pericentric spreading of these NF1 partial copies.
相似文献
3.
Arbour NC; Zlotogora J; Knowlton RG; Merin S; Rosenmann A; Kanis AB; Rokhlina T; Stone EM; Sheffield VC 《Human molecular genetics》1997,6(5):689-694
Achromatopsia is an autosomal recessive disease of the retina,
characterized clinically by an inability to distinguish colors, impaired
visual acuity, nystagmus and photophobia. A genome-wide search for linkage
was performed using an inbred Jewish kindred from Iran. To facilitate the
genome-wide search, we utilized a DNA pooling strategy which takes
advantage of the likelihood that the disease in this inbred kindred is
inherited by all affected individuals from a common founder. Equal molar
amounts of DNA from all affected individuals were pooled and used as the
PCR template for short tandem repeat polymorphic markers (STRPs). Pooled
DNA from unaffected members of the kindred was used as a control. A
reduction in the number of alleles in the affected versus control pool was
observed at several loci. Upon genotyping of individual family members,
significant linkage was established between the disease phenotype and
markers localized on chromosome 2. The highest LOD score observed was 5.4
(theta = 0). When four additional small unrelated families were genotyped,
the combined peak LOD score was 8.2. Analysis of recombinant chromosomes
revealed that the disease gene lies within a 30 cM interval which spans the
centromere. Additional fine-mapping studies identified a region of
homozygosity in all affected individuals, narrowing the region to 14 cM. A
candidate gene for achromatopsia was excluded from this disease interval by
radiation hybrid mapping. Linkage of achromatopsia to chromosome 2 is an
essential first step in the identification of the disease-causing gene.
相似文献
4.
Yoshiteru Konaka Michael A. Norcross Vernon C. Maino Richard T. Smith 《European journal of immunology》1981,11(6):445-450
Rabbit anti-Thy-1 antibody bound to T cells induces the appearance of T cell growth factor (interleukin 2, IL 2) receptors and the production of IL 2. IL2 receptors induction by this means occurs within a short time span, and independent of any demonstrable accessory cell. A source of exogenous or endogenous IL 2 is apparently the only requirement for proliferation after these receptors are expressed. IL 2 production, on the other hand, is accessory cell-dependent, and this help is mediated via Fc receptors on the accessory cell. IL 2 production in this model is demonstrable at 4–6 h, or earlier, and is proliferation-independent. X-irradiation actually augments apparent IL 2 production. The data are consistent with the hypothesis that a differentiated subset of T cells in any mixed population is responsible for IL 2 production. 相似文献
5.
Two-hundred and eighty bacterial isolates from wound and soft tissue infections were studied for species identification and antibiotic resistance pattern. Amongst them 122 isolates were from community acquired infection and 158 were from nosocomial infections. The common community acquired pathogens were Staphylococcus aureus (67.8%) and Streptococcus pyogenes (10.7%), whereas Staphylococcus aureus (60.1%) and E. Coli (8.9%) were common in nosocomial infection. Only two anaerobes (Cl perfringens) were isolated. Penicillin resistance was found to be 87% and 92% for Staphylococccus aureus in community acquired and noscomial infections respectively. 85% of Proteus isolates were resistant to ampicillin. There was relatively lower level of resistance by all isolates to cefotaxime. Gentamicin showed higher rate of resistance than netilmicin and amikacin. Resistance of E. coli isolates to fluoroquinolones being 79% for norfloxacin, 81% for ciprofloxacin and 60% for ofloxacin. The study showed a higher resistance of methicillin resistant Staphylococcus aureus (MRSA) to other antibiotics. Amikacin and ofloxacin were the best recommended drugs for empirical therapy for all organisms, the susceptibility rate being 80.7% and 80.4%.KEY WORDS: Antibiotic resistance, Soft tissue infections, Wound infections 相似文献
6.
目的观察再发性低血糖后脑内葡萄糖转运蛋白1(glucose transporter 1,GLUT1)及葡萄糖转运蛋白3(GLUT3)表达的变化,从而探讨无症状低血糖的发生机制。方法将80只15日龄野生型小鼠随机分为正常对照组及低血糖组,每组40只。低血糖组给予正规胰岛素腹腔注射3次,每次剂量为5U/kg,对照组注射等体积生理盐水。两组分别在最后1次注射后12、24、48及72 h处死小鼠取脑组织(每组每时间点10只),应用免疫组化方法观察小鼠脑内GLUT1及GLUT3表达的变化。结果低血糖后脑内微血管上GLUT1表达有增加趋势,皮质增加高于海马,72 h皮质GLUT1表达显著高于对照组;低血糖后48、72 h皮质及海马GLUT3表达均显著高于相应对照组。结论再发性低血糖后脑内GLUT1及GLUT3适应性增高,这种适应既能节省神经元的能量代谢,但也能削减神经元对低血糖的反应。 相似文献
7.
D Nitti A Marchet E Mammano A Ambrosi C Belluco R Mencarelli M Maino G Marconato F Farinati M Lise 《European journal of surgical oncology》2005,31(8):875-881
AIMS: To investigate the survival benefit of extended lymphadenectomy (D2) in EGC patients in one European Institution. METHODS: A review was made of our prospective gastric database from January 1980 to December 2001. Of 527 patients with primary gastric adenocarcinoma, 119 with EGC underwent potentially curative resection (R0) with D2 lymphadenectomy. RESULTS: There were two post-operative deaths. Of the 117 evaluable cases, 96 were classified as N0 and 21 as N+, with metastases in the perigastric lymph nodes (level 1) in 13, and beyond this site (level 2) in eight. Five-year survival was 85.9 and 83.0% in N0 and N+ patients, respectively. During a median follow-up of 90 months, five of the eight patients with level 2 metastases died of recurrent disease and three were alive. The estimated survival benefit for 119 patients with EGC was 2.5% (3/119 cases). CONCLUSIONS: In patients with EGC, metastases to level 2 are rare. Our results indicate that D2 lymphadenectomy has a limited survival benefit and that in these cases a less extensive lymphadenectomy (D1) could be performed. 相似文献
8.
9.
10.
Thrombopoietin (Tpo), the ligand for the c-Mpl receptor, is a major regulator of megakaryopoiesis. Treatment of mice with Tpo raises the platelet count fourfold within a few days. Conversely, c-mpl knock-out mice have platelet counts that are 15% that of normal. The subunit structure of the c-Mpl receptor is not fully understood. Some cytokines that stimulate megakaryopoiesis (IL-6, IL-11, leukemia inhibitory factor, and oncostatin M) bind to receptors that use gp130 as a signal transduction subunit. For these reasons, we determined whether gp130 function was required for Tpo-induced signal transduction. Murine marrow cells were cultured in semi-solid media in the presence of Tpo or IL-3, with or without a neutralizing anti-gp130 monoclonal antibody (RX187) or a soluble form of c-Mpl receptor (soluble Mpl) that blocks Tpo bioactivity, and the numbers of colony-forming unit-megakaryocyte (CFU-Meg) colonies were counted on day 5. Murine marrow cells were also cultured in suspension under serum-free conditions for 5 days, and megakaryocyte DNA content was measured by flow cytometry, as an index of nuclear maturation. The addition of RX187 did not block Tpo-induced CFU-Meg colony growth nor CFU-Meg nuclear maturation in suspension culture. However, IL-3-induced CFU-Meg colony growth and megakaryocyte nuclear maturation decreased in the presence of RX187. Soluble Mpl completely ablated Tpo-induced CFU-Meg growth, and partially blocked IL- 3-stimulated CFU-Meg growth. Thus the effects of Tpo on megakaryopoiesis in vitro do not depend on cytokines that signal through gp130. Furthermore, it is unlikely that gp 130 serves as a beta chain for the c-Mpl receptor, as Tpo signalling is unimpaired in the presence of RX187. In contrast, the effects of IL-3 on CFU-Meg growth are mediated in part through Tpo and through gp130-signalling cytokines. 相似文献