全文获取类型
收费全文 | 111688篇 |
免费 | 9883篇 |
国内免费 | 6500篇 |
专业分类
耳鼻咽喉 | 1259篇 |
儿科学 | 1449篇 |
妇产科学 | 1254篇 |
基础医学 | 14068篇 |
口腔科学 | 1917篇 |
临床医学 | 12898篇 |
内科学 | 16769篇 |
皮肤病学 | 2014篇 |
神经病学 | 5750篇 |
特种医学 | 5019篇 |
外国民族医学 | 40篇 |
外科学 | 11430篇 |
综合类 | 16283篇 |
现状与发展 | 34篇 |
一般理论 | 12篇 |
预防医学 | 7483篇 |
眼科学 | 3182篇 |
药学 | 12158篇 |
86篇 | |
中国医学 | 5510篇 |
肿瘤学 | 9456篇 |
出版年
2024年 | 854篇 |
2023年 | 1424篇 |
2022年 | 3537篇 |
2021年 | 4810篇 |
2020年 | 3614篇 |
2019年 | 3262篇 |
2018年 | 3566篇 |
2017年 | 3273篇 |
2016年 | 3445篇 |
2015年 | 5088篇 |
2014年 | 6356篇 |
2013年 | 6042篇 |
2012年 | 9092篇 |
2011年 | 9510篇 |
2010年 | 6069篇 |
2009年 | 5217篇 |
2008年 | 6701篇 |
2007年 | 6330篇 |
2006年 | 5972篇 |
2005年 | 5574篇 |
2004年 | 4003篇 |
2003年 | 3980篇 |
2002年 | 3354篇 |
2001年 | 2373篇 |
2000年 | 2226篇 |
1999年 | 2092篇 |
1998年 | 1317篇 |
1997年 | 1224篇 |
1996年 | 992篇 |
1995年 | 935篇 |
1994年 | 811篇 |
1993年 | 566篇 |
1992年 | 732篇 |
1991年 | 625篇 |
1990年 | 555篇 |
1989年 | 521篇 |
1988年 | 389篇 |
1987年 | 383篇 |
1986年 | 296篇 |
1985年 | 264篇 |
1984年 | 118篇 |
1983年 | 107篇 |
1982年 | 67篇 |
1981年 | 65篇 |
1980年 | 40篇 |
1979年 | 47篇 |
1974年 | 27篇 |
1973年 | 27篇 |
1972年 | 23篇 |
1970年 | 21篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
Sang Hyun Ryu Doo Hun Lee Yoon‐Joo Ko Sang Moon Lee Hae Jin Kim Kyoung Chul Ko Seung Uk Son 《Macromolecular chemistry and physics.》2019,220(11)
This work shows the sensing performance of conjugated microporous polymer (CMP) tubes. Aligned tubular CMP films (CMP‐AT) are synthesized by a template method. The Sonogashira coupling of tetra(4‐ethynyl)phenylethylene with 1,4‐diiodobenzene in the cylindrical pores of anodic aluminum oxide (AAO) plates and the etching of templates result in the CMP‐AT films. Due to the tetraphenylethylene moieties in the materials, the CMP‐AT films show aggregation‐induced emission (AIE). Based on emission‐quenching behavior, the sensing performance of CMP‐AT films toward model explosives, nitrotoluenes, is studied. The CMP‐AT films having longer CMP tubes with thinner wall thickness show better sensing performance with the Stern–Volmer constant (Ksv) values up to 92 400 M?1 toward 2,4‐dinitrotoluene. The reduced diffusion pathway of substrates by the thin wall of the CMP tubes is critical for the AIE quenching‐based sensing of nitrotoluenes. These observations indicate that the functionality of CMP materials can be further enhanced by their morphological engineering. Due to the chemical stability of CMP materials, the CMP‐AT‐5 film can be recycled at least five times, maintaining the original sensing performance and tubular morphology. 相似文献
32.
Inflammation Research - Both type 1 diabetes (T1D) and type 2 diabetes (T2D) are classified as forms of diabetes mellitus (DM) and commonly considered inflammatory process. Intercellular adhesion... 相似文献
33.
Xiu‐Feng Huang Lue Xiang Xiao‐Long Fang Wei‐Qin Liu You‐Yuan Zhuang Zhen‐Ji Chen Ren‐Juan Shen Wan Cheng Ru‐Yi Han Si‐Si Zheng Xue‐Jiao Chen Xiaoling Liu Zi‐Bing Jin 《Human mutation》2019,40(8):1039-1045
Retinitis pigmentosa (RP) is the most common manifestation of inherited retinal diseases with high degree of genetic, allelic, and phenotypic heterogeneity. CEP250 encodes the C‐Nap1 protein and has been associated with various retinal phenotypes. Here, we report the identification of a mutation (c.562C>T, p.R188*) in the CEP250 in a consanguineous family with nonsyndromic RP. To gain insights into the molecular pathomechanism underlying CEP250 defects and the functional relevance of CEP250 variants in humans, we conducted a functional characterization of CEP250 variant using a novel Cep250 knockin mouse line. Remarkably, the disruption of Cep250 resulted in severe impairment of retinal function and significant retinal morphological alterations. The homozygous knockin mice showed significantly reduced retinal thickness and ERG responses. This study not only broadens the spectrum of phenotypes associated with CEP250 mutations, but also, for the first time, elucidates the function of CEP250 in photoreceptors using a newly established animal model. 相似文献
34.
In the present study, the growth of a single isolate of Candida albicans on saliva-, serum-coated or protein free (uncoated), thermocycled (4-70 degrees C for 1 min, respectively; 0, 1000 and 10 000 times) 15 commercial maxillofacial materials was investigated, by monitoring pH changes in growth media. The inhibitory effect of the tissue conditioners on fungal growth was analysed using three parameters viz: (i) delay in the onset of the rapid decline in pH (ii) reduction in the rate of pH change and (iii) the pH minima reached. In the case of control materials (non-thermocycled and uncoated), significant antifungal effect was observed with two products. However, the antifungal effect of the materials was significantly reduced both by thermal cycling (Analysis of covariance [ANOVA]; P < 0.01) and a layer of protein coating (saliva, P < 0.05; serum, P < 0.01). When the interrelation between three parameters of fungal growth and the surface hydrophobicity of the materials were analysed, minimum pH of fungal growth on 10 000-thermocycled materials correlated well with the contact angles of the materials (Student t-test, P < 0.01), suggesting that thermocycling process reduced the unpolymerized components of the materials which showed the antifungal effects, resulted in that the cell growth depends on the surface hydrophobicity of the specimens. These results, taken together, suggest that the ageing of the materials and the biological fluids of the host enhanced the fungal growth on maxillofacial materials. 相似文献
35.
MacDougall M Simmons D Gu TT Forsman-Semb K Mårdh CK Mesbah M Forest N Krebsbach PH Yamada Y Berdal A 《European journal of oral sciences》2000,108(4):303-310
Amelogenesis imperfecta is a broad classification of hereditary enamel defects, exhibiting both genetic and clinical diversity. Most amelogenesis imperfecta cases are autosomal dominant disorders, yet only the local hypoplastic form has been mapped to human chromosome 4q between D4S242 1 and the albumin gene. An enamel protein cDNA, termed ameloblastin (also known as amelin and sheathlin), has been isolated from rat, mouse and pig. Its human homolog has been mapped to chromosome 4q21 between markers D4S409 and D4S400, flanking the local hypoplastic amelogenesis imperfecta critical region. Therefore, ameloblastin is a strong candidate gene for this form of amelogenesis imperfecta. To facilitate genetic studies related to this dental disease, we isolated and characterized a human ameloblastin cDNA. A human third molar cDNA library was screened and two ameloblastin clones identified. Nucleotide sequencing of these cDNAs indicated alternative splicing of the putative open reading frame, use of different polyadenylation signals, and a high degree of similarity to reported rat, mouse and porcine cDNAs. Immunohistochemistry studies on embryonic human teeth using an antibody to recombinant ameloblastin indicated ameloblastin expression by ameloblasts with localization in the enamel matrix associated with the sheath structures. 相似文献
36.
Enamelin maps to human chromosome 4q21 within the autosomal dominant amelogenesis imperfecta locus 总被引:6,自引:0,他引:6
Amelogenesis imperfecta is a group of hereditary enamel defects. Of the autosomal dominant forms, only the local hypoplastic type has been mapped to human chromosome 4q 13-4q21. Enamelin is a large enamel matrix protein secreted by ameloblasts. The purpose of this study was to determine the human chromosomal localization of enamelin to establish an association with various forms of amelogenesis imperfecta. Chromosomal mapping was performed by polymerase chain reaction (PCR) amplification using somatic hybrid and deletion/derivation cell line panels with an enamelin primer set based on 100% conserved regions between pig and mouse cDNAs. Sequence-tagged site content mapping using eight markers within the critical local hypoplastic amelogenesis imperfecta region was then performed using an isolated human enamelin genomic BAC clone. The human enamelin amplicon was confirmed by DNA sequence analysis, revealing 81% and 73% identity to pig and mouse cDNAs, respectively. PCR amplification using a somatic cell hybrid panel placed enamelin on chromosome 4 with analysis of a regional chromosome 4 mapping panel refining the localization to 4q 13.1-q21.23. An identified human enamelin BAC genomic clone was shown to contain markers D4S2604 and D4S2670, as well as the first exon of the human ameloblastin gene, placing enamelin in the critical amelogenesis imperfecta locus between markers HIS1 and D4S2604 at 4q21. Our results suggest that enamelin is a strong candidate gene for this disease. Furthermore, human 4q21 may contain a second cluster of enamel matrix genes located proximally to the identified cluster of dentin and bone genes. 相似文献
37.
38.
五倍子对感染根管内厌氧菌抑制作用的体外研究 总被引:4,自引:0,他引:4
目的:观察中药五倍子对感染根管内几种常见优势专性厌氧菌和兼性厌氧菌的抑菌作用。方法:采用试管二倍稀释法,测定五倍子水提取物在体外环境下对厌氧消化链球菌、内氏放线菌、具核梭杆菌、中间普雷沃菌、金黄色葡萄球菌、大肠杆菌的最小抑菌浓度(MIC)和杀菌浓度(MBC),同时以氢氧化钙做对照。结果:五倍子对各种试验菌株均有抑制作用,对不同的菌株,MIC和MBC值不同,而氢氧化钙对内氏放线菌、金黄色葡萄球菌、大肠杆菌在试验浓度范围内无抑制作用。结论:五倍子水提取物抗菌效果较好且广泛,用于根管内封药具有一定的应用前景。 相似文献
39.
Background and Objective: Platelet‐derived growth factor‐BB is a potent mediator of tooth‐supporting periodontal tissue repair and regeneration. A limitation of the effects of topical platelet‐derived growth factor‐BB application is its short half‐life in vivo. Gene therapy has shown strong promise for the long‐term delivery of platelet‐derived growth factor in both skin ulcer healing and periodontal tissue engineering. However, little is known regarding the extended effects of platelet‐derived growth factor‐B on cell signaling via gene delivery, especially at the level of phosphorylation of intracellular kinases. This study sought to evaluate the effect of gene transfer by Ad‐PDGF‐B on human gingival fibroblasts (HGFs) and the subsequent regulation of genes and cell‐surface proteins associated with cellular signaling. Material and Methods: HGFs from human subjects were treated by adenoviral PDGF‐B, PDGF‐1308 (a dominant negative mutant of PDGF) and recombinant human platelet‐derived growth factor‐BB, and then incubated in serum‐free conditions for various time points and harvested at 1, 6, 12, 24, 48, 72 and 96 h. Exogenous PDGF‐B was measured by RT‐PCR and Western blot. Cell proliferation was evaluated by [methyl‐3H]thymidine incorporation assay. We used proteomic arrays to explore phosphorylation patterns of 23 different intracellular kinases after PDGF‐B gene transfer. The expression of α and β PDGFR and Akt were measured by Western blot analysis. Results: Sustained in vitro expression of PDGF‐B in HGFs by Ad‐PDGF‐B transduction was seen at both the mRNA and protein levels. Compared to rhPDGF‐BB and Ad‐PDGF‐1308, Ad‐PDGF‐B maintained cell growth in serum‐free conditions, with robust increases in DNA synthesis. Gene delivery of PDGF‐B also prolonged downregulation of the growth arrest specific gene (gas) PDGFαR. Of the 23 intracellular kinases that we tested in proteomic arrays, Akt revealed the most notable long‐term cell signaling effect as a result of the over‐expression of Ad‐PDGF‐B, compared with pulse recombinant human platelet‐derived growth factor BB. Prolonged Akt phosphorylation was induced by treatment with Ad‐PDGF‐B, for at least up to 96 h. Conclusion: These findings further demonstrate that gene delivery of PDGF‐B displays sustained signal transduction effects in human gingival fibroblasts that are higher than those conveyed by treatment with recombinant human platelet‐derived growth factor‐BB protein. These data on platelet‐derived growth factor gene delivery contribute to an improved understanding of these pathways that are likely to play a role in the control of clinical outcomes of periodontal regenerative therapy. 相似文献
40.
The aim of this investigation was to study the remodelling of cartilage in the mandibular condyle following disc displacement (DD) of the temporomandibular joint (TMJ). Forty adult Japanese white rabbits were used in this study. The right joints of 28 of the 40 rabbits had their discs surgically displaced. Four of the 28 were killed at 4 days or 1, 2, 4, 6, 8 and 12 weeks after surgery. The messenger RNA (mRNA) expression levels of aggrecan and type II collagen in cartilages were measured using in situ hybridization techniques. Results showed that aggrecan mRNA expression reduced in the first week after DD. The expression began to recover after 4 weeks and reached a normal level after 6 weeks. Type II collagen mRNA expression reduced from 4 weeks and the expression recovered after 8 weeks. This suggests that the chondrocyte reacting to the displacement of the TMJ disc, alters its matrix gene expression patterns and it is may be the cause of the shape changes of TMJ after DD. 相似文献