首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   574篇
  免费   49篇
耳鼻咽喉   19篇
儿科学   40篇
妇产科学   3篇
基础医学   82篇
口腔科学   57篇
临床医学   78篇
内科学   150篇
皮肤病学   3篇
神经病学   40篇
特种医学   19篇
外科学   61篇
预防医学   17篇
药学   24篇
肿瘤学   30篇
  2024年   1篇
  2023年   7篇
  2022年   10篇
  2021年   30篇
  2020年   29篇
  2019年   28篇
  2018年   28篇
  2017年   28篇
  2016年   23篇
  2015年   16篇
  2014年   43篇
  2013年   27篇
  2012年   37篇
  2011年   58篇
  2010年   22篇
  2009年   23篇
  2008年   28篇
  2007年   44篇
  2006年   25篇
  2005年   22篇
  2004年   20篇
  2003年   15篇
  2002年   21篇
  2001年   7篇
  2000年   2篇
  1999年   3篇
  1998年   3篇
  1997年   6篇
  1996年   1篇
  1988年   1篇
  1985年   1篇
  1981年   2篇
  1980年   1篇
  1977年   3篇
  1973年   1篇
  1970年   1篇
  1963年   3篇
  1962年   1篇
  1961年   1篇
  1960年   1篇
排序方式: 共有623条查询结果,搜索用时 15 毫秒
1.
In an attempt to identify common disease susceptibility alleles for breast cancer, we performed a combined analysis of three genome-wide association studies (GWAS), involving 2,702 women of European ancestry with invasive breast cancer and 5,726 controls. Tests for association were performed for 285,984 SNPs. Evidence for association with SNPs in genes in specific pathways was assessed using a permutation-based approach. We confirmed associations with loci reported by previous GWAS on 1p11.2, 2q35, 3p, 5p12, 8q24, 10q23.13, 14q24.1 and 16q. Six SNPs with the strongest signals of association with breast cancer, and which have not been reported previously, were typed in two further studies; however, none of the associations could be confirmed. Suggestive evidence for an excess of associations was found for genes involved in the regulation of actin cytoskeleton, glycan degradation, alpha-linolenic acid metabolism, circadian rhythm, hematopoietic cell lineage and drug metabolism. Androgen and oestrogen metabolism, a pathway previously found to be associated with the development of postmenopausal breast cancer, was marginally significant (P = 0.051 [unadjusted]). These results suggest that further analysis of SNPs in these pathways may identify associations that would be difficult to detect through agnostic single SNP analyses. More effort focused in these aspects of oncology can potentially open up promising avenues for the understanding of breast cancer and its prevention.  相似文献   
2.
3.
Objective The aim of the study was to evaluate the inflammatory response to surgical trauma in minilaparotomy cholecystectomy (MC) compared to laparoscopic cholecystectomy (LC). Assessment of inflammatory response to surgical trauma in MC has not been addressed properly. Therefore, we investigated five interleukins (IL) and C-reactive protein (CRP) in MC versus LC group in a prospective randomised trial. Methods Initially, 106 patients with non-complicated symptomatic gallstone disease were randomised into MC (n?=?56) or LC (n?=?50) groups. Plasma levels of five interleukins (IL-1β, IL-1ra, IL-6, IL-8, IL-10) and hs-CRP were measured at three time points; before operation (PRE), immediately after operation (POP1) and six hours after operation (POP2). The primary end-point of the study was to compare the plasma levels of five interleukins and CRP in LC versus MC group. Results The demographic variables and the surgical data were similar in the study groups. The patients in the MC group had higher elevation of the CRP mean values post-operatively (p?=?0.01). However, the patients in the MC group had higher elevation of the IL-1ra mean values post-operatively, the mean pre-/post-operative IL-1ra values being 299/614?pg/ml in the MC group versus 379/439?pg/ml in the LC group (p?=?0.003). There was no statistical significance in IL-6 mean values between the MC and LC groups pre- and post-operatively (POP1). However, the patients in the MC group had higher IL-6 mean values six hours post-operatively (POP2), the mean IL-6 values being 27.6?pg/ml in the MC group versus 14.8?pg/ml in the LC group (p?=?0.037). In addition, the patients in the MC group had higher elevation of the IL-6 mean values post-operatively, the mean pre-/post-operative IL-6 values being 4.1/27.6?pg/ml in the MC group versus 3.8/14.8?pg/ml in the LC group (p?=?0.04). There was no statistical significance in IL-8, IL-10, and IL-1β mean values between the MC and LC groups pre- and post-operatively. Conclusion Our results suggest that the inflammatory response in MC versus LC groups was similar based on the IL-8, IL-10, and IL-1β values. A new finding with possible clinical relevance in the present work is higher relative elevation of the IL-1ra and IL-6 mean values post-operatively in the MC group.  相似文献   
4.
Vascular endothelial growth factor (VEGF) is a hypoxia-inducible endothelial cell mitogen and survival factor. Its receptor VEGFR-2 (KDR/Flk-1) mediates these effects. We studied the expression of VEGF and VEGFR-2 in ischemic human and rabbit skeletal muscle by immunohistochemistry and in situ hybridization. Human samples were obtained from eight lower limb amputations because of acute or chronic critical ischemia. In chronically ischemic human skeletal muscle VEGF and VEGFR-2 expression was restricted to atrophic and regenerating skeletal myocytes, whereas in acutely ischemic limbs VEGF and VEGFR-2 were expressed diffusely in the affected muscle. Hypoxia-inducible factor-1alpha was associated with VEGF and VEGFR-2 expression both in acute and chronic ischemia but not in regeneration. Hindlimb ischemia was induced in 20 New Zealand White rabbits by excising the femoral artery. Magnetic resonance imaging and histological sections revealed extensive ischemic damage in the thigh and leg muscles of ischemic rabbit hindlimbs with VEGF expression similar to acute human lower limb ischemia. After 1 and 3 weeks of ischemia VEGF expression was restricted to regenerating myotubes and by 6 weeks regeneration and expression of VEGF was diminished. VEGFR-2 expression was co-localized with VEGF expression in regenerating myotubes. Macrophages and an increased number of capillaries were associated with areas of ischemic muscle expressing VEGF and VEGFR-2. In conclusion, two patterns of VEGF and VEGFR-2 expression in human and rabbit ischemic skeletal muscle are demonstrated. In acute skeletal muscle ischemia VEGF and VEGFR-2 are expressed diffusely in the affected muscle. In chronic skeletal muscle ischemia and in skeletal muscle recovering from ischemia VEGF and VEGFR-2 expression are restricted to atrophic and regenerating muscle cells suggesting the operation of an autocrine pathway that may promote survival and regeneration of myocytes.  相似文献   
5.
Background: Lately, renewed interest has arisen in the new forms of allergen immunotherapy because they may offer alternatives for drug treatment. Objective: The purpose of this study was to develop a well-characterized preparation of the main respiratory cow dander allergen, Bos d 2, with attenuated allergenic activity. Methods: The immunologic characteristics of Bos d 2 preparations were studied by indirect IgE ELISA, ELISA inhibition, Western blotting, histamine release, skin prick tests, and the proliferation tests of allergen-specific T-cell clones. Results: The complete recombinant Bos d 2 was observed to bind effectively, IgE of cow-allergic patients in indirect ELISA. In other experiments, the IgE-binding capacity of recombinant Bos d 2 proved to be lower compared with native Bos d 2. When the two overlapping recombinant fragments of Bos d 2 (corresponding amino acids 1-131 and 81-172, respectively) covering the whole molecule were compared with the complete recombinant Bos d 2 with several methods, only a low level of residual reactivity was observed. For example, recombinant fragments could not bind antibody at all in ELISA inhibition tests retaining, however, some reactivity in skin prick tests. In contrast, the fragments were able to stimulate vigorously Bos d 2-specific T-cell clones. Conclusion: The approach we have taken may offer a simple and reproducible way to produce hypoallergenic preparations for immunotherapy, circumventing simultaneously some of the problems of other experimental methods such as individual T-cell epitope recognition in peptide-based immunotherapy. (J Allergy Clin Immunol 1997;100:721-7.)  相似文献   
6.
7.
We have previously proposed that mammalian lipocalin allergens are recognized suboptimally by the human immune system due to their homology with endogenous lipocalins. Here, we have characterized in detail the human T cell recognition of one of the previously identified T cell epitopes of the major dog allergen Can f 1, contained in peptide p105–120. A panel of peptide analogues (altered peptide ligands, APLs) of p105–120 was tested on two specific T cell clones restricted by different human leukocyte antigen (HLA) alleles. Interestingly, we identified for both of the clones several heteroclitic APLs that were capable of stimulating them at 10–30-fold lower concentrations than the natural peptide. Moreover, one of the heteroclitic APLs identified with the T cell clones, L115F, was observed to induce a stronger polyclonal T cell response than the natural allergen peptide from the peripheral blood mononuclear cells (PBMCs) of six Can f 1-allergic subjects studied. The heteroclitic APLs bound with the same affinity as p105–120 to common HLA-DR- and HLA-DP-alleles, suggesting that their improved stimulatory capacity is attributable to a more efficient T cell receptor (TCR) recognition rather than increased HLA binding. Collectively, our data suggest that p105–120 is recognized suboptimally by human T cells. This may contribute to the allergenicity of Can f 1.  相似文献   
8.
Objective : To resolve if TBX22 mutations cause isolated tongue-tie in the Finnish population. Design : Mutation analysis of the coding region of the TBX22 gene in 50 Finnish isolated tongue-tie patients and 61 control samples. Results : One putative sequence variation was identified from two male patients, but whether this represents a polymorphism or causative mutation remains unknown. Conclusions : Mutations in the coding region of the TBX22 gene are not a major cause of ankyloglossia in the Finnish population and do not explain the sex difference or inheritance of tongue-tie.  相似文献   
9.
10.
Dental implants are prone to bacterial colonization which may result in bone destruction and implant loss. Treatments of peri-implant disease aim to reduce bacterial adherence while leaving the implant surface intact for attachment of bone-regenerating host cells. The aims of this study were to investigate the antimicrobial efficacy of gaseous ozone on bacteria adhered to various titanium and zirconia surfaces and to evaluate adhesion of osteoblast-like MG-63 cells to ozone-treated surfaces. Saliva-coated titanium (SLA and polished) and zirconia (acid etched and polished) disks served as substrates for the adherence of Streptococcus sanguinis DSM20068 and Porphyromonas gingivalis ATCC33277. The test specimens were treated with gaseous ozone (140 ppm; 33 mL/s) for 6 and 24 s. Bacteria were resuspended using ultrasonication, serially diluted and cultured. MG-63 cell adhesion was analyzed with reference to cell attachment, morphology, spreading, and proliferation. Surface topography as well as cell morphology of the test specimens were inspected by SEM. The highest bacterial adherence was found on titanium SLA whereas the other surfaces revealed 50-75% less adherent bacteria. P. gingivalis was eliminated by ozone from all surfaces within 24 s to below the detection limit (≥99.94% reduction). S. sanguinis was more resistant and showed the highest reduction on zirconia substrates (>90% reduction). Ozone treatment did not affect the surface structures of the test specimens and did not influence osteoblastic cell adhesion and proliferation negatively. Titanium (polished) and zirconia (acid etched and polished) had a lower colonization potential and may be suitable material for implant abutments. Gaseous ozone showed selective efficacy to reduce adherent bacteria on titanium and zirconia without affecting adhesion and proliferation of osteoblastic cells. This in vitro study may provide a solid basis for clinical studies on gaseous ozone treatment of peri-implantitis and revealed an essential base for sufficient tissue regeneration.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号