全文获取类型
收费全文 | 18065篇 |
免费 | 1517篇 |
国内免费 | 37篇 |
专业分类
耳鼻咽喉 | 128篇 |
儿科学 | 692篇 |
妇产科学 | 523篇 |
基础医学 | 2311篇 |
口腔科学 | 229篇 |
临床医学 | 2048篇 |
内科学 | 3414篇 |
皮肤病学 | 305篇 |
神经病学 | 1971篇 |
特种医学 | 298篇 |
外国民族医学 | 5篇 |
外科学 | 1945篇 |
综合类 | 144篇 |
一般理论 | 67篇 |
预防医学 | 2734篇 |
眼科学 | 264篇 |
药学 | 1144篇 |
1篇 | |
中国医学 | 38篇 |
肿瘤学 | 1358篇 |
出版年
2024年 | 43篇 |
2023年 | 281篇 |
2022年 | 484篇 |
2021年 | 912篇 |
2020年 | 551篇 |
2019年 | 755篇 |
2018年 | 860篇 |
2017年 | 613篇 |
2016年 | 628篇 |
2015年 | 692篇 |
2014年 | 901篇 |
2013年 | 1149篇 |
2012年 | 1593篇 |
2011年 | 1611篇 |
2010年 | 824篇 |
2009年 | 666篇 |
2008年 | 1139篇 |
2007年 | 1196篇 |
2006年 | 960篇 |
2005年 | 894篇 |
2004年 | 808篇 |
2003年 | 722篇 |
2002年 | 534篇 |
2001年 | 70篇 |
2000年 | 55篇 |
1999年 | 58篇 |
1998年 | 110篇 |
1997年 | 75篇 |
1996年 | 37篇 |
1995年 | 48篇 |
1994年 | 40篇 |
1993年 | 39篇 |
1992年 | 28篇 |
1991年 | 17篇 |
1990年 | 15篇 |
1989年 | 20篇 |
1987年 | 9篇 |
1986年 | 14篇 |
1985年 | 16篇 |
1984年 | 15篇 |
1983年 | 6篇 |
1982年 | 10篇 |
1981年 | 14篇 |
1980年 | 13篇 |
1978年 | 5篇 |
1977年 | 9篇 |
1976年 | 5篇 |
1975年 | 7篇 |
1974年 | 8篇 |
1961年 | 5篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
Detection and characterization of hepatitis C virus RNA in seminal plasma and spermatozoon fractions of semen from patients attempting medically assisted conception 下载免费PDF全文
82.
83.
Vascular Endothelial Growth Factor/Vascular Permeability Factor Is Temporally and Spatially Correlated with Ocular Angiogenesis in a Primate Model 总被引:19,自引:2,他引:19 下载免费PDF全文
Joan W. Miller Anthony P. Adamis David T. Shima Patricia A. D'Amore Rachel S. Moulton Michael S. O'Reilly Judah Folkman Harold F. Dvorak Lawrence F. Brown Brygida Berse Tet-Kin Yeo Kiang-Teck Yeo 《The American journal of pathology》1994,145(3):574-584
Ischemia often precedes neovascularization. Inocular neovascularization, such as occurs in diabetic retinopathy, a diffusible angiogenic factor has been postulated to be produced by ischemicretina and to lead to neovascularization of theretina, optic nerve, or iris. However, no angiogenic factor has been conclusively identified that satisfies this hypothesis. Vascular endothelial growth factor/vascular permeability factor, hereafter referred to as VEGF, is a likely candidate for an ocular angiogenic factor because it is a secreted mitogen, specific for endothelial cells, and is upregulated by hypoxia. We investigated the association of VEGF with the development of experimental iris neovascularization in the cynomolgus monkey. Following theproduction of retinal ischemia by laser occlusion of all branch retinal veins, VEGF was increased in the aqueous fluid, and the aqueous VEGF levels changed synchronously and proportionally with the severity of iris neovascularization. Northern analysis and in situ hybridization revealed that VEGF messenger RNA is upregulated in the ischemic retina. These observations support the hypothesis that ocular neovascularization is regulated by a diffusible factor and identify VEGF as a likely candidate for a retina-derived vascular permeability and angiogenesis factor in vivo. 相似文献
84.
Staphylococcus epidermidis has been reported to bind to a number of host cell extracellular matrix proteins, including fibronectin. Here we report the identification of a fibronectin-binding protein from S. epidermidis. A phage display library of S. epidermidis genomic DNA was constructed and panned against immobilized fibronectin. A number of phagemid clones containing overlapping inserts were identified, and one of these clones, pSE109FN, contained a 1.4-kb insert. Phage pSE109FN was found to bind to fibronectin but not to collagen, fibrinogen, laminin, or vitronectin. However, pSE109FN also bound to heparin, hyaluronate, and plasminogen, although to a lesser extent than it bound to fibronectin. Analysis of The Institute for Genomic Research S. epidermidis genome sequence database revealed a 1.85-kb region within a putative 30.5-kb open reading frame, to which the overlapping DNA inserts contained within the fibronectin-binding phagemids mapped. We have designated the gene encoding the fibronectin-binding domain embp. A recombinant protein, Embp32, which encompassed the fibronectin-binding domain of Embp, blocked the binding of S. epidermidis, but not the binding of Staphylococcus aureus, to fibronectin. In contrast, a recombinant protein, FnBPB[D1-D4], spanning the fibronectin-binding domain of the S. aureus fibronectin-binding protein FnBPB, blocked binding of S. aureus to fibronectin but had a negligible effect on the binding of S. epidermidis. 相似文献
85.
The authors hypothesized that the progesterone component of some hormone replacement therapies in women is detrimental to cognition. A previous study showed that ovariectomy (ovx) in aged rats enhanced spatial working memory and decreased elevated progesterone levels. The current study evaluated whether progesterone administration counteracts these cognitive enhancing effects of ovx. Aged sham and aged ovx rats given progesterone exhibited compromised learning of the working and reference memory components of the task, and made more working memory errors on the latter testing days compared with aged ovx rats not given progesterone. Results suggest that whereas ovx of the aged female rat enhances learning and the ability to handle numerous items of spatial working memory information, progesterone is detrimental to these aspects of performance. These findings may speak to studies in menopausal women which suggest that combination hormone therapies have a negative impact on cognition. 相似文献
86.
Absence of proteinase-activated receptor-1 signaling affords protection from bleomycin-induced lung inflammation and fibrosis 下载免费PDF全文
Howell DC Johns RH Lasky JA Shan B Scotton CJ Laurent GJ Chambers RC 《The American journal of pathology》2005,166(5):1353-1365
Activation of the coagulation cascade is commonly observed in the lungs of patients with both acute and chronic inflammatory and fibrotic lung disorders, as well as in animal models of these disorders. The aim of this study was to examine the contribution of the major thrombin receptor, proteinase-activated receptor-1 (PAR-1), during the acute inflammatory and chronic fibrotic phases of lung injury induced by intratracheal instillation of bleomycin in mice. Inflammatory cell recruitment and increases in bronchoalveolar lavage fluid (BALF) protein were attenuated by 56 +/- 10% (P < 0.05) and 53 +/- 12% (P < 0.05), respectively, in PAR-1-deficient (PAR-1-/-) mice compared with wild-type (WT) mice. PAR-1-/- mice were also protected from bleomycin-induced pulmonary fibrosis with total lung collagen accumulation reduced by 59 +/- 5% (P < 0.05). The protection afforded by PAR-1 deficiency was accompanied by significant reductions in pulmonary levels of the potent PAR-1-inducible proinflammatory and profibrotic mediators, monocyte chemoattractant protein-1 (MCP-1), transforming growth factor-beta-1 (TGF-beta1), and connective tissue growth factor/fibroblast-inducible secreted protein-12 (CTGF/FISP12). In addition, PAR-1 was highly expressed in inflammatory and fibroproliferative lesions in lung sections obtained from patients with fibrotic lung disease. These data show for the first time that PAR-1 signaling plays a key role in experimentally induced lung injury, and they further identify PAR-1 as one of the critical receptors involved in orchestrating the interplay between coagulation, inflammation, and remodeling in response to tissue injury. 相似文献
87.
Effect of dosage on immunogenicity of a Vi conjugate vaccine injected twice into 2- to 5-year-old Vietnamese children 总被引:2,自引:0,他引:2 下载免费PDF全文
Canh DG Lin FY Thiem VD Trach DD Trong ND Mao ND Hunt S Schneerson R Robbins JB Chu C Shiloach J Bryla DA Bonnet MC Schulz D Szu SC 《Infection and immunity》2004,72(11):6586-6588
In a double-blind, randomized, and placebo-controlled previous trial, the efficacy of Vi-rEPA for typhoid fever in 2- to 5-year-olds was 89.0% for 46 months. Vi-rEPA contained 25 microg of Vi and induced a greater-than-eightfold rise in immunoglobulin G (IgG) anti-Vi in all of the vaccinees tested. In this investigation, we conducted a dosage-immunogenicity study of 5, 12.5, and 25 microg of Vi-rEPA in this age group. Two doses of Vi-rEPA were injected 6 weeks apart. Blood samples were taken before and at 10 weeks (4 weeks after the second injection) and 1 year later. All postimmunization geometric mean (GM) levels were higher than the preimmune levels (P < 0.0001). At 10 weeks, the GM IgG anti-Vi level elicited by 25 microg (102 EU/ml) was higher than those elicited by 12.5 microg (74.7 EU/ml) and 5 microg (43 EU/ml) (P < 0.004): all of the children had > or = 3.52 EU/ml (estimated minimum protective level). One year later, the levels declined about sevenfold (13.3 and 11.3 versus 6.43 EU/ml, P < 0.0001) but remained significantly higher than the preimmune levels (P < 0.0001), and >96% of the children had a greater-than-eightfold rise. This study also confirmed the safety and consistent immunogenicity of the four lots of Vi-rEPA used in this and previous trials. 相似文献
88.
BrkA confers resistance to killing by complement in Bordetella pertussis. Complement resistance in Bordetella bronchiseptica was examined. Four B. bronchiseptica strains possessed the brkA gene; however, only three expressed the protein. Only the strain lacking BrkA was susceptible to complement. Introduction of the B. pertussis brkA gene restored BrkA expression to this strain but did not confer resistance. brkA was mutated in the strains that naturally expressed BrkA, and loss of BrkA did not confer sensitivity to complement. As a species, B. bronchiseptica is more resistant to complement than B. pertussis, and BrkA does not mediate resistance. 相似文献
89.
Silencing of Fas, but not caspase-8, in lung epithelial cells ameliorates pulmonary apoptosis, inflammation, and neutrophil influx after hemorrhagic shock and sepsis 总被引:6,自引:0,他引:6 下载免费PDF全文
Perl M Chung CS Lomas-Neira J Rachel TM Biffl WL Cioffi WG Ayala A 《The American journal of pathology》2005,167(6):1545-1559
Apoptosis and inflammation play an important role in the pathogenesis of direct/pulmonary acute lung injury (ALI). However, the role of the Fas receptor-driven apoptotic pathway in indirect/nonpulmonary ALI is virtually unstudied. We hypothesized that if Fas or caspase-8 plays a role in the induction of indirect ALI, their local silencing using small interfering RNA (siRNA) should be protective in hemorrhage-induced septic ALI. Initially, as a proof of principle, green fluorescent protein-siRNA was administered intratracheally into transgenic mice overexpressing green fluorescent protein. Twenty-four hours after siRNA delivery, lung sections revealed a significant decrease in green fluorescence. Intratracheally administered Cy-5-labeled Fas-siRNA localized primarily in pulmonary epithelial cells. Intratracheal instillation of siRNA did not induce lung inflammation via toll-like receptor or protein kinase PKR pathways as assessed by lung tissue interferon-alpha, tumor necrosis factor-alpha, and interleukin (IL)-6 levels. Mice subjected to hemorrhagic shock and sepsis received either Fas-, caspase-8-, or control-siRNA intratracheally 4 hours after hemorrhage. Fas- or caspase-8-siRNA significantly reduced lung tissue Fas or caspase-8 mRNA, respectively. Only Fas-siRNA markedly diminished lung tissue tumor necrosis factor-alpha, IL-6, IL-10, interferon-gamma, IL-12, and caspase-3 activity. Fas-siRNA also preserved alveolar architecture and reduced lung neutrophil infiltration and pulmonary epithelial apoptosis. These data indicate the pathophysiological significance of Fas activation in nonpulmonary/shock-induced ALI and the feasibility of intrapulmonary administration of anti-apoptotic siRNA in vivo. 相似文献
90.
Randomised controlled trial to compare GP-run orthopaedic clinics based in hospital outpatient departments and general practices 下载免费PDF全文
Richard Baker Jo Sanderson-Mann Stephen Longworth Rachel Cox Clare Gillies 《The British journal of general practice》2005,55(521):912-917
BACKGROUND: To reduce outpatient waiting times, a growing number of outpatient clinics for selected groups of patients are being provided by GPs with special interests (GPwSIs). AIM: To determine whether there are differences in patient satisfaction or clinical outcome among patients attending orthopaedic clinics provided by GPwSIs in hospital or community settings. DESIGN OF STUDY: Randomised controlled trial. SETTING: Hospital outpatient departments or general practices. METHOD: Three hundred and twenty-one patients with minor orthopaedic problems were referred by GPs to the orthopaedic surgery department of the University Hospitals of Leicester NHS Trust; 168 patients were randomised to care by GPwSIs in practices, and 153 were randomised to care by the same GPwSIs in clinics held at hospital outpatient departments. Patients completed the SF-36v2 and satisfaction questionnaires at their first appointment, and again 3 months later. RESULTS: There was no significant difference between the sites in changes in health. After the first clinic attendance, patients attending practice-based clinics were more satisfied with access to appointments and information received. CONCLUSION: For selected orthopaedic referrals seen by GPwSIs, there were no significant differences in clinical outcomes between practice-based and hospital-based clinics, but some features of practice-based clinics tend to be preferred by patients. 相似文献