全文获取类型
收费全文 | 13982篇 |
免费 | 1116篇 |
国内免费 | 45篇 |
专业分类
耳鼻咽喉 | 123篇 |
儿科学 | 334篇 |
妇产科学 | 338篇 |
基础医学 | 1965篇 |
口腔科学 | 362篇 |
临床医学 | 1482篇 |
内科学 | 2933篇 |
皮肤病学 | 244篇 |
神经病学 | 1026篇 |
特种医学 | 722篇 |
外国民族医学 | 17篇 |
外科学 | 1830篇 |
综合类 | 148篇 |
一般理论 | 6篇 |
预防医学 | 1315篇 |
眼科学 | 178篇 |
药学 | 933篇 |
中国医学 | 20篇 |
肿瘤学 | 1167篇 |
出版年
2021年 | 173篇 |
2020年 | 131篇 |
2019年 | 195篇 |
2018年 | 258篇 |
2017年 | 160篇 |
2016年 | 239篇 |
2015年 | 266篇 |
2014年 | 333篇 |
2013年 | 467篇 |
2012年 | 632篇 |
2011年 | 614篇 |
2010年 | 364篇 |
2009年 | 365篇 |
2008年 | 593篇 |
2007年 | 585篇 |
2006年 | 584篇 |
2005年 | 557篇 |
2004年 | 542篇 |
2003年 | 549篇 |
2002年 | 520篇 |
2001年 | 510篇 |
2000年 | 549篇 |
1999年 | 488篇 |
1998年 | 207篇 |
1997年 | 176篇 |
1996年 | 168篇 |
1995年 | 140篇 |
1994年 | 125篇 |
1993年 | 123篇 |
1992年 | 357篇 |
1991年 | 311篇 |
1990年 | 299篇 |
1989年 | 264篇 |
1988年 | 272篇 |
1987年 | 229篇 |
1986年 | 262篇 |
1985年 | 235篇 |
1984年 | 192篇 |
1983年 | 173篇 |
1982年 | 99篇 |
1981年 | 98篇 |
1980年 | 107篇 |
1979年 | 152篇 |
1978年 | 116篇 |
1977年 | 100篇 |
1976年 | 79篇 |
1975年 | 89篇 |
1974年 | 105篇 |
1973年 | 117篇 |
1971年 | 86篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
101.
Role of Escherichia coli K capsular antigens during complement activation, C3 fixation, and opsonization. 总被引:2,自引:0,他引:2
下载免费PDF全文
![点击此处可从《Infection and immunity》网站下载免费的PDF全文](/ch/ext_images/free.gif)
W C Van Dijk H A Verbrugh M E van der Tol R Peters J Verhoef 《Infection and immunity》1979,25(2):603-609
Escherichia coli strains with K capsular polysaccharides are relatively resistant to phagocytosis by polymorphonuclear leukocytes, in contrast to E. coli strains without K antigens. This inhibition of phagocytosis is related to an impaired recognition of the K+ strains by the phagocytes due to ineffective opsonization. All five strains without K antigens were readily phagocytized after opsonization in 5% normal serum, compared with no uptake of the K+ strains. Evidence is presented that the decreased opsonization of the K+ strains in normal serum is caused by a low rate of complement activation of the strains, with subsequent absence of C3b fixation or C3d fixation or both to the cell wall of the bacteria. After removal of the K+ antigens by heating of a K+ E. coli strain, the strain was able to activate complement, to bind C3b or C3d or both, and to become opsonized. Complement was then activated via the classical and alternative pathways, which was comparable to the complement consumption by K- E. coli. 相似文献
102.
S P Peters R S Tung M Chatham E R Bleecker L M Lichtenstein 《International archives of allergy and applied immunology》1985,76(4):344-349
Circulating human basophils contain histamine, a potent mediator of inflammation. Previous in vitro studies have shown that histamine 'releasability' in asthmatic subjects differs from normal subjects but have not evaluated possible differences in the immunopharmacological control of the release of this mediator which might account for these differences. The purpose of the present study was to examine the immunopharmacologic control of basophil histamine release in 14 asthmatics and 10 normal subjects who were characterized by pulmonary function tests, allergic status (skin tests and serum IgE levels) and nonspecific airways reactivity to methacholine and histamine. Basophils were stimulated with anti-IgE, and the inhibitory effects of the H2 agonist, dimaprit, and dibutyryl cyclic AMP (dbcAMP), as well as the enhancing properties of 5-hydroperoxyeicosatetraenoic acid (5-HPETE) and indomethacin on the modulation of histamine release, were investigated. Although no statistically significant differences were seen in the percent histamine release triggered by anti-IgE in these two groups, enhancement of histamine release by 5-HPETE was more consistent in the asthmatic subjects (10 of 10) than in control subjects (6 of 8). The percent increase in histamine release produced by 5-HPETE in asthmatic subjects averaged 3.9 +/- 1.3% using 0.03 micrograms anti-IgE/ml and 4.8 +/- 3.2% using 0.1 microgram anti-IgE/ml (p less than 0.002, Wilcoxon's signed rank test), and averaged 3.0 +/- 4.3 and 3.1 +/- 5.3%, respectively, in control subjects (p greater than 0.10).(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
103.
104.
N. M. Thomson I. J. Simpson D. J. Evans D. K. Peters 《Clinical and experimental immunology》1975,20(3):527-535
The role of fibrin deposition in experimental (crescentic) nephritis in rabbits, due to chronic immune complex deposition induced by BSA, has been studied. Fibrin deposition was prevented and in such animals crescent formation inhibited, suggesting that, as in experimental nephritis due to anti-GBM antibodies, fibrin deposition plays a major pathogenetic role in epithelial cell proliferation. However, in defibrinated animals, mesangial and endothelial cell proliferation, polymorpho-nuclear leucocyte infiltration and impairment of renal function could still occur. These studies are further evidence that defibrination may be of benefit in the treatment of rapidly progressive glomerulonephritis in man. 相似文献
105.
Background
Since its sudden appearance and link to microcephaly in 2015, the number of PubMed references for Zika virus (ZIKV) has risen from 181 to 5163, at time of writing, with a vast proportion focused on the consequences of ZIKV infection during pregnancy. This level of attention underlies increased demand for sensitive and specific diagnostic tools able to assess risk to an unborn child, as well as to understand the dynamics and consequences of viral persistence.Aim
Review the expanding knowledge on ZIKV persistence and diagnostic challenges and summarize current advancements in detection.Sources
Peer-reviewed articles based on the search terms ‘Zika’ and ‘ZIKV’ combined with the terms ‘diagnostics’ ‘point-of-care diagnostics’ ‘viral load’ ‘persistence’ ‘detection’ ‘treatment’ ‘nucleic acid amplification testing’ ‘microsphere’ ‘PVRT’ ‘RVNT’ ‘RT-LAMP’ ‘NASBA’ SIBA’ ‘RPA’ ‘SHERLOCK’ ‘ELISA’, and ‘TMA’ as well as laboratory experience of the authors.Content
Topics covered include the emergence of the ZIKV epidemic, pathogenesis of ZIKV infection, the nature of ZIKV persistence, complications in serological diagnosis, tried and novel diagnostic laboratory techniques, and a recent accounting of point-of-care testing (POCT) methods.Implications
Surveillance and research in the case of ZIKV has shifted into a more rapid and coordinated worldwide directive than has occurred with most viral epidemics to date. The particular concentration of outbreaks in resource-limited settings increases the need for simple assays capable of reliable, inexpensive, high-throughput ZIKV diagnosis. This review serves to both catalogue current diagnostic options and consider their suitability at point-of-care. 相似文献106.
Androgen receptor YAC transgenic mice carrying CAG 45 alleles show trinucleotide repeat instability 总被引:1,自引:15,他引:1
La Spada AR; Peterson KR; Meadows SA; McClain ME; Jeng G; Chmelar RS; Haugen HA; Chen K; Singer MJ; Moore D; Trask BJ; Fischbeck KH; Clegg CH; McKnight GS 《Human molecular genetics》1998,7(6):959-967
X-linked spinal and bulbar muscular atrophy (SBMA) is caused by a CAG
repeat expansion in the first exon of the androgen receptor (AR) gene.
Disease-associated alleles (37-66 CAGs) change in length when transmitted
from parents to offspring, with a significantly greater tendency to shift
size when inherited paternally. As transgenic mice carrying human AR cDNAs
with 45 and 66 CAG repeats do not display repeat instability, we attempted
to model trinucleotide repeat instability by generating transgenic mice
with yeast artificial chromosomes (YACs) carrying AR CAG repeat expansions
in their genomic context. Studies of independent lines of AR YAC transgenic
mice with CAG 45 alleles reveal intergenerational instability at an overall
rate of approximately 10%. We also find that the 45 CAG repeat tracts are
significantly more unstable with maternal transmission and as the
transmitting mother ages. Of all the CAG/CTG repeat transgenic mice
produced to date the AR YAC CAG 45 mice are unstable with the smallest
trinucleotide repeat mutations, suggesting that the length threshold for
repeat instability in the mouse may be lowered by including the appropriate
flanking human DNA sequences. By sequence-tagged site content analysis and
long range mapping we determined that one unstable transgenic line has
integrated an approximately 70 kb segment of the AR locus due to
fragmentation of the AR YAC. Identification of the cis - acting elements
that permit CAG tract instability and the trans -acting factors that
modulate repeat instability in the AR YAC CAG 45 mice may provide insights
into the molecular basis of trinucleotide repeat instability in humans.
相似文献
107.
A.L. Peters E.K. van de Weerdt F. Prinsze D. de Korte N.P. Juffermans A.P.J. Vlaar 《Transfusion Clinique et Biologique》2019,26(1):10-17
Objective
To investigate the relation between donor characteristics and TRALI incidence.Background
Transfusion-related acute lung injury (TRALI) is a potentially fatal complication of transfusion. In pre-clinical studies and several clinical studies, TRALI has been related to loss of product quality during red blood cell (RBC) storage, called the “storage lesion”. Donor characteristics, as for example age, genetics and life style choices influence this “storage lesion”. We hypothesized that donor sex, age and blood type is related to TRALI incidence.Methods/materials
We performed a secondary analysis of two cohort studies, designed to identify TRALI risk factors by matching TRALI patients to transfused controls. We obtained donor sex, age and blood type from the Dutch Blood Bank Sanquin and investigated TRALI incidence in patients who were exposed to a certain donor characteristic. We used Kruskal-Wallis testing to compare the number of transfused products and Chi2 testing to compare proportions of TRALI patients and transfused control.Results
After implementation of the male-donor only plasma strategy, patients received more transfusion products from male donors. However, we did not detect a relation between TRALI incidence and donor sex. Both TRALI patients and transfused controls received mainly products from donors over 41 years old, but donor age did not influence TRALI risk. Donor blood type, the transfusion of blood type-compatible and blood type-matched products also had no influence on TRALI incidence.Conclusion
We conclude that in two cohorts of TRALI patients, donor age, donor sex and donor blood type are unrelated to TRALI. 相似文献108.
The role of polymorphonuclear leucocytes in the autologous phase of nephrotoxic nephritis. 总被引:9,自引:8,他引:9
下载免费PDF全文
![点击此处可从《Clinical and experimental immunology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
P F Naish N M Thomson I J Simpson D K Peters 《Clinical and experimental immunology》1975,22(1):102-111
The role of polymorphonuclear leucocytes (PMN) in the autologous phase of nephrotoxic nephritis (NTN) in the rabbit has been investigated. Depletion of circulating PMN by nitrogen mustard protected renal function and immunofluorescent examination showed reduction in glomerular fibrin deposition. Depletion of circulating PMN using a highly specific goat anti-PMN serum (APS) provided similar protection of renal function, highly significant reduction in proteinuria and histological and immunofluorescent examination showed reduced glomerular PMN infiltration, extracapillary cell proliferation and virtual absence of fibrin deposition. Although protection by nitrogen mustard may have been partly due to immunosuppression, no reduction in antibody response was detected in the APS-treated rabbits. The results implicate the polymorph as the principal injurious agent in this model of NTN, responsible directly or indirectly for both proteinuria and glomerular fibrin deposition. 相似文献
109.
Sala F Mulet J Reddy KP Bernal JA Wikman P Valor LM Peters L König GM Criado M Sala S 《Neuroscience letters》2005,373(2):144-149
The effects of various Flustra foliacea metabolites on different types of human neuronal nicotinic acetylcholine receptors (nAChRs) expressed in Xenopus oocytes were investigated. Whereas most of the compounds tested had a small blocking effect, one of them, deformylflustrabromine, selectively increased the current obtained in alpha4beta2 receptors when co-applied with acetylcholine (ACh). The current increase was reversible and concentration-dependent. This potentiating effect was still present at saturating concentrations of acetylcholine, and no changes in single-channel conductance or reversal potential were observed, thus suggesting a modification in the gating of alpha4beta2 receptors. Dwell time analysis of single channel records indicates that the mechanism of action of deformylflustrabromine could be both an increase of the opening rate constant and a decrease of the closing rate constant on alpha4beta2 receptors. Thus, deformylflustrabromine may constitute an excellent starting point for the future development of related agents able to potentiate human neuronal nicotinic receptor function. 相似文献
110.
The eggshells of young developmental stages in the uterus are rather thin and homogenous. In the brezel stage of Brugia malayi they are 35 nm thick and 20 nm in Litomosoides carinii. In young developmental stages up to brezel stages the eggshells bind the lectins WGA, DBA and PNA labelled with colloidal gold. This shows that GlcNAc, GalNAc and Gal residues are present at the surface of the sheath. In intrauterine microfilariae of B. malayi the original sheath is reduced to a thickness of 7 nm. It is reinforced by secretions from a specialized area of the epithelium of the uterus which do not appear as a homogeneous layer but look like a string of pearls. This layer may be called the uterine layer. It has a thickness of 40–80 nm. In the microfilaria of L. carinii, the thickness of the original sheath is reduced to 2–3 nm and the uterine layer has a thickness of 7 nm. The uterine layer does not react with any of the lectins, which shows that the surface lacks N-acetylglucosamine, N-acetylgalactosamine and galactose residues. The uterine layer appears to be an ancestral (plesiomorphic) feature which is present in free-living nematodes and the highly specialized bloodforms of filariae. The uterine layer seems to protect and disguise the original sheath against the immune reactions of the host.Supported by the WHO Onchocerciasis Chemotherapy Project (OCT) 相似文献