全文获取类型
收费全文 | 21160篇 |
免费 | 1445篇 |
国内免费 | 96篇 |
专业分类
耳鼻咽喉 | 223篇 |
儿科学 | 556篇 |
妇产科学 | 432篇 |
基础医学 | 3330篇 |
口腔科学 | 532篇 |
临床医学 | 2077篇 |
内科学 | 4650篇 |
皮肤病学 | 531篇 |
神经病学 | 2486篇 |
特种医学 | 626篇 |
外科学 | 1803篇 |
综合类 | 109篇 |
一般理论 | 13篇 |
预防医学 | 1840篇 |
眼科学 | 417篇 |
药学 | 1336篇 |
中国医学 | 78篇 |
肿瘤学 | 1662篇 |
出版年
2024年 | 36篇 |
2023年 | 207篇 |
2022年 | 410篇 |
2021年 | 693篇 |
2020年 | 465篇 |
2019年 | 655篇 |
2018年 | 698篇 |
2017年 | 532篇 |
2016年 | 631篇 |
2015年 | 742篇 |
2014年 | 881篇 |
2013年 | 1097篇 |
2012年 | 1768篇 |
2011年 | 1884篇 |
2010年 | 1001篇 |
2009年 | 905篇 |
2008年 | 1477篇 |
2007年 | 1477篇 |
2006年 | 1392篇 |
2005年 | 1304篇 |
2004年 | 1206篇 |
2003年 | 1085篇 |
2002年 | 926篇 |
2001年 | 112篇 |
2000年 | 73篇 |
1999年 | 117篇 |
1998年 | 180篇 |
1997年 | 154篇 |
1996年 | 111篇 |
1995年 | 87篇 |
1994年 | 68篇 |
1993年 | 48篇 |
1992年 | 31篇 |
1991年 | 22篇 |
1990年 | 34篇 |
1989年 | 21篇 |
1988年 | 15篇 |
1987年 | 18篇 |
1986年 | 7篇 |
1985年 | 11篇 |
1984年 | 12篇 |
1983年 | 14篇 |
1982年 | 11篇 |
1981年 | 9篇 |
1980年 | 15篇 |
1979年 | 9篇 |
1978年 | 7篇 |
1977年 | 8篇 |
1975年 | 6篇 |
1973年 | 7篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
Albertini-Yagi CS Oliveira RC Vieira JE Negri EM de Oliveira LR Saldiva PH Lorenzi-Filho G 《Respiratory physiology & neurobiology》2005,145(1):101-110
The study objectives were to compare in vitro transportability and physical properties of respiratory mucus, obtained invasively by direct collection (DC) right after endotracheal intubation and non-invasively by sputum induction with 3% hypertonic saline solution inhalation (SI) 24 h before the anesthesia. Twenty-two patients with no pulmonary disease scheduled for elective abdominal surgical procedures were studied. The parameters analyzed and the main results are as follows. (1) Transportability by cilia (MCT), SI was higher than DC (0.94+/-0.25 and 0.62+/-0.25; P<0.001). There was a significant correlation between the two methods and DC could be estimated by: DC=0.21+(0.44 SI) (r=0.44; P<0.001). (2) Transportability by cough (CC), SI was higher than DC (68.23+/-32.1 and 33.58+/-19.04 mm; P=0.002). (3) Contact angle (CA), SI was lower than DC (10+/-3 degrees and 22+/-14 degrees ; P=0.025). (4) Rheological properties (no significant difference obtained between SI and DC). These results indicated that SI changes mucus physical properties and transportability in non-expectorators. 相似文献
82.
Distribution of putative adhesins in different seropathotypes of Shiga toxin-producing Escherichia coli
下载免费PDF全文
![点击此处可从《Journal of clinical microbiology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Toma C Martínez Espinosa E Song T Miliwebsky E Chinen I Iyoda S Iwanaga M Rivas M 《Journal of clinical microbiology》2004,42(11):4937-4946
The distribution of eight putative adhesins that are not encoded in the locus for enterocyte effacement (LEE) in 139 Shiga toxin-producing Escherichia coli (STEC) of different serotypes was investigated by PCR. Five of the adhesins (Iha, Efa1, LPF(O157/OI-141), LPF(O157/OI-154), and LPF(O113)) are encoded in regions corresponding to genomic O islands of E. coli EDL933, while the other three adhesins have been reported to be encoded in the STEC megaplasmid of various serotypes (ToxB [O157:H7], Saa [O113:H21], and Sfp [O157:NM]). STEC strains were isolated from humans (n = 54), animals (n = 52), and food (n = 33). They were classified into five seropathotypes (A through E) based on the reported occurrence of STEC serotypes in human disease, in outbreaks, and in the hemolytic-uremic syndrome (M. A. Karmali, M. Mascarenhas, S. Shen, K. Ziebell, S. Johnson, R. Reid-Smith, J. Isaac-Renton, C. Clark, K. Rahn, and J. B. Kaper, J. Clin. Microbiol. 41:4930-4940, 2003). The most prevalent adhesin was that encoded by the iha gene (91%; 127 of 139 strains), which was distributed in all seropathotypes. toxB and efa1 were present mainly in strains of seropathotypes A and B, which were LEE positive. saa was present only in strains of seropathotypes C, D, and E, which were LEE negative. Two fimbrial genes, lpfA(O157/OI-141) and lpfA(O157/OI-154), were strongly associated with seropathotype A. The fimbrial gene lpfA(O113) was present in all seropathotypes except for seropathotype A, while sfpA was not present in any of the strains studied. The distribution of STEC adhesins depends mainly on serotypes and not on the source of isolation. Seropathotype A, which is associated with severe disease and frequently is involved in outbreaks, possesses a unique adhesin profile which is not present in the other seropathotypes. The wide distribution of iha in STEC strains suggested that it could be a candidate for vaccine development. 相似文献
83.
84.
Raboni SM Probst CM Bordignon J Zeferino A dos Santos CN 《Journal of medical virology》2005,76(4):553-562
We sequenced the complete S segments of hantaviruses detected from 12 HPS patients living in southern of Brazil. Samples were obtained from patients diagnosed in different years, in distinct areas, and with a broad spectrum of clinical signs. Despite these differences, all the S proteins of hantavirus from Paraná were identical, except for one amino acid substitution. Phylogenetic analyses of the complete S segment nucleotide and amino acid sequences indicated that hantaviruses from Paraná form a distinct clade from those circulating in South and North America. Other hantaviruses from Brazil were not placed in the same clade. The Oligoryzomys nigripes-associated strains ITA37 and ITA38 from Paraguay were found to belong to the same clade as the hantaviruses from Paraná. Paraguay and Paraná state are located at the same latitude and some ecosystems are similar in both places. The geographic position and common rodent hosts could explain this phylogenetic relationship. 相似文献
85.
Rivera A Fisher SA Fritsche LG Keilhauer CN Lichtner P Meitinger T Weber BH 《Human molecular genetics》2005,14(21):3227-3236
Age-related macular degeneration (AMD) is a multifactorial disease and a prevalent cause of visual impairment in developed countries. Risk factors include environmental components and genetic determinants. The complement factor H (CFH) has been the first major susceptibility gene for AMD identified within 1q32. Here, we focused on a second region of interest in 10q26 where a recent meta-analysis revealed strongest evidence for linkage to AMD at a genome-wide significance level. Within an interval of 22 Mb, we have analyzed 93 single nucleotide polymorphisms for allelic association with AMD in two independent case-control cohorts of German origin (AMD(combined) n=1166; controls(combined) n=945). Significant association was found across a 60 kb region of high linkage disequilibrium harboring two genes PLEKHA1 and hypothetical LOC387715. The strongest association (P=10(-34)) centered over a frequent coding polymorphism, Ala69Ser, at LOC387715, strongly implicating this gene in the pathogenesis of AMD. Besides abundant expression in placenta, we demonstrate weak expression of LOC387715 in the human retina. At present, however, there is no functional information on this gene, which appears to have evolved recently within the primate lineage. The joint contribution of the common risk allele at LOC387715, Ala69Ser, and at CFH, Tyr402His, was assessed in our case-control population, which suggests an additive model indicating an independent contribution of the two gene loci to disease risk. Our data show a disease odds ratio of 57.6 (95% CI: 37.2, 89.0) conferred by homozygosity for risk alleles at both CFH and LOC387715 when compared with the baseline non-risk genotype. 相似文献
86.
Karacsonyi C Bedke T Hinrichsen N Schwinzer R Lindner R 《Journal of leukocyte biology》2005,78(5):1097-1105
Major histocompatibility complex class II (MHC II) peptide complexes can associate with lipid rafts, and this is a prerequisite for their recruitment to the immunological synapse and for efficient T cell stimulation. One of the most often used criterion for raft association is the resistance to extraction by the detergent Triton X-100 (TX-100) at low temperature. For MHC II, a variety of detergents have been used under different conditions, leading to variable and often conflicting conclusions about the association of MHC II with detergent-resistant membranes (DRMs). To clarify whether these inconsistencies were caused by variations in the isolation protocols or reflect different biochemical properties of MHC II lipid complexes, we used two standardized procedures for the isolation of membranes resistant to TX-100, 3-[(3-cholamidopropyl)dimethylammonio]-1-propanesulfonate (CHAPS), or Brij 98. Our results suggest that some of the reported variations in the association of MHC II with DRMs are caused by differences in the methods. We also show that in our hands, specific and efficient flotation of MHC II and the MHC II-associated invariant chain from mouse B-lymphoma cells was only achieved with Brij 98, but not with TX-100 and CHAPS. We furthermore used DRMs prepared from hen egg lysozyme-fed B-lymphoma cells to activate the T cell hybridoma 3A9. In agreement with our biochemical data, T cell activation could only be achieved with Brij 98- but not with TX-100-resistant membranes. Thus, MHC II and also the invariant chain belong to a set of proteins comprising the T cell receptor, prominin, and the prion protein, which reside in membrane environments distinct from conventional lipid rafts. 相似文献
87.
emm Gene distribution among erythromycin-resistant and -susceptible Italian isolates of Streptococcus pyogenes
下载免费PDF全文
![点击此处可从《Journal of clinical microbiology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Zampaloni C Cappelletti P Prenna M Vitali LA Ripa S 《Journal of clinical microbiology》2003,41(3):1307-1310
The phenotypes and genetic determinants for macrolide resistance were determined for 167 erythromycin-resistant Streptococcus pyogenes strains. A cMLS phenotype was shown in 18% of the erythromycin-resistant strains, while inducible resistance was apparent in 31% and the M phenotype was apparent in 50%. The emm gene type of this set of resistant isolates and that of 48 erythromycin-sensitive isolates were determined. emm2 and emm48 were recorded only in the resistant strains of the M phenotype, while approximately all of the strains harboring the emm22 gene had the cMLS phenotype. More than 80% of the emm89-positive strains had the iMLS phenotype, and the same portion of emm4 strains presented the M phenotype. emm3 is recorded only among sensitive strains. The distribution of frequencies of the genetic determinant for the virulence factor M protein was significantly different both among organisms of different types of resistance and between resistant and sensitive populations of S. pyogenes under study. 相似文献
88.
Settmacher B Rheinheimer C Hamacher H Ames RS Wise A Jenkinson L Bock D Schaefer M Köhl J Klos A 《European journal of immunology》2003,33(4):920-927
The anaphylatoxic peptide C3a is a pro-inflammatory mediator generated during complement activation, whose specific G protein coupled receptor is expressed on granulocytes, monocytes, mast cells, activated lymphocytes, and in the nervous tissue. We have generated RBL-2H3 cell clones stably expressing mutants of the human C3a-receptor (C3aR) with combined alanine (Ala) substitutions of ten C-terminal serine (Ser) or threonine (Thr) residues, which may represent putative phosphorylation sites to characterize their role in ligand-induced C3aR internalization and signaling. Ser475/479 and Thr480/481 as well as Ser449 seemed not to be involved in ligand-induced receptor internalization. Either directly or by a conformational change they even "inhibit" C3aR internalization. In contrast, mutants with Ala substitutions at Ser465/470 and Thr463/466 were poorly internalized, and Thr463 seemed to be the most important C-terminal Thr or Ser residue directly effecting receptor internalization. However, it is likely that other C3aR regions additionally participate in this negative feed-back mechanism since even mutants with multiple Ala substitutions still internalized to a limited degree. Interestingly, in a mutant with a single exchange of Ser449 to Ala, the signal transduction assessed by a Ca(2+) assay and [(35)S]GTP gamma S-binding on HEK cells transiently co-transfected with G-alpha 16 or G-alpha O, respectively, was severely impaired, indicating that this residue of C3aR is involved in G protein coupling. 相似文献
89.
Micci F Walter CU Teixeira MR Panagopoulos I Bjerkehagen B Saeter G Heim S 《Cancer Genetics and Cytogenetics》2003,144(2):119-124
Endometrial stromal sarcomas (ESS) are rare neoplasms with the capacity both to invade the myometrium locally and to give rise to extrauterine metastases. Cytogenetic abnormalities have been reported in 22 cases of ESS, mostly involving rearrangements of chromosomes 6, 7, and 17. The most characteristic translocation of this tumor type, t(7;17)(p15 approximately p21;q12 approximately q21), was recently shown to generate a JAZF1/JJAZ1 fusion gene. We report three additional cases of ESS with abnormal karyotypes, whose interpretation was based on the combined analysis by conventional cytogenetics and cross-species color banding FISH (RxFISH). The combination of G-banding and RxFISH in every case gave additional information beyond that obtained by either technique alone, determining the identity of even complex inter- as well as intrachromosomal rearrangements. In one of the three tumors, a t(7;17) was seen; molecular genetic studies identified the JAZF1/JJAZ1 fusion gene in this case. Two tumors had aberrations that included structural changes of chromosome arms 6p and 7p. Evidently, karyotypic, and hence pathogenetic, heterogeneity exists for tumors classified as endometrial stromal sarcomas based on their phenotypic features. 相似文献
90.
Integrating complementary and alternative medicine instruction into health professions education: organizational and instructional strategies. 总被引:1,自引:0,他引:1
Mary Y Lee Rita Benn Leslie Wimsatt Jane Cornman Joan Hedgecock Susan Gerik Janice Zeller Mary Jo Kreitzer Pamela Allweiss Claudia Finklestein Aviad Haramati 《Academic medicine》2007,82(10):939-945
A few years ago, the National Institutes of Health National Center for Complementary and Alternative Medicine funded a program called the Complementary and Alternative Medicine (CAM) Education Project. Grantees were 14 medical and nursing schools and the American Medical Student Association, which funded six additional medical schools. Grants were awarded in cohorts of five per year in 2000, 2001, and 2002-2003.The R25 grant recipients identified several major themes as crucial to the success of integrating CAM into health professions curricula. The rationale for integrating CAM curricula was in part to enable future health professionals to provide informed advice as patients dramatically increase the use of CAM. Success of new CAM education programs relied on leadership, including top-down support from institutions' highest administrators. Formal and informal engagement of key faculty and opinion leaders raised awareness, interest, and participation in programs. A range of faculty development efforts increased CAM-teaching capacity. The most effective strategies for integration addressed a key curriculum need and used some form of evidence-based practice framework. Most programs used a combination of instructional delivery strategies, including experiential components and online resources, to address the needs of learners while promoting a high level of ongoing interest in CAM topics. Institutions noted several benefits, including increased faculty development activities, the creation of new programs, and increased cross- and inter-university collaborations. Common challenges included the need for qualified faculty, crowded and changing curricula, a lack of defined best practices in CAM, and post-grant sustainability of programs. 相似文献