全文获取类型
收费全文 | 108篇 |
免费 | 16篇 |
专业分类
124篇 |
出版年
2022年 | 1篇 |
2021年 | 5篇 |
2020年 | 6篇 |
2019年 | 8篇 |
2018年 | 6篇 |
2017年 | 4篇 |
2016年 | 9篇 |
2015年 | 10篇 |
2014年 | 5篇 |
2013年 | 2篇 |
2012年 | 6篇 |
2011年 | 4篇 |
2010年 | 5篇 |
2009年 | 2篇 |
2008年 | 2篇 |
2007年 | 2篇 |
2006年 | 6篇 |
2005年 | 4篇 |
2004年 | 2篇 |
2003年 | 1篇 |
2002年 | 3篇 |
2001年 | 1篇 |
2000年 | 4篇 |
1999年 | 2篇 |
1998年 | 7篇 |
1997年 | 1篇 |
1996年 | 1篇 |
1995年 | 3篇 |
1994年 | 2篇 |
1993年 | 1篇 |
1992年 | 2篇 |
1989年 | 4篇 |
1978年 | 1篇 |
1977年 | 1篇 |
1975年 | 1篇 |
排序方式: 共有124条查询结果,搜索用时 15 毫秒
91.
92.
OI Klychnikov AV Drabkin OV Vasilenko YS Pavlov MS Trofimova IN Smolenskaya AA Rozenkranz AS Sobolev AV Babakov 《Biochemistry. Biokhimii?a》1998,63(9):1083-1089
Higher plant plasma membranes carry receptors of different affinity for the phytotoxin fusicoccin. Reception of fusicoccin involves proteins belonging to the highly conserved 14-3-3 family, but the complete structure of the fusicoccin receptor (FCR) is unknown. Using radiation inactivation analysis, we estimated the molecular masses of low-affinity and high-affinity FCR at 63 +/- 7 and 130 +/- 15 kD, respectively. The dose dependences of receptor inactivation indicate that microsomal specimens contain "silent" FCRs of 420 +/- 90 kD in amounts commensurate with that of the active FCRs. Both low- and high-affinity FCRs are inactivated by hydrolytic enzymes from the outer surface of the plasma membrane, and impairment of protoplast integrity causes an irreversible transition of the low-affinity binding site into the high-affinity one. A scheme is proposed for the organization of different types of FCR in the plasma membrane, implying that the membrane affinity for fusicoccin reflects the interaction between proteins in the FCR complex. 相似文献
93.
Biotinyl-oligosaccharides are a relatively new generation of saccharide
probes that enable immobilization of desired oligosaccharides on
streptavidin matrices for studies of carbohydrate-protein interactions.
Here we describe the facile preparation of biotinyl-l-3-(2-naphthyl)-
alanine hydrazide (BNAH) derivatives of oligosaccharides, containing a
strong UV absorbing and fluorescent group, in which the ring of the
reducing-end monosaccharide is nonreduced. We evaluate reactivities of
immobilized BNAH- N -glycans with plant lectins that recognize aspects of
the oligosaccharide core or outer-arms. We make some comparisons with
2-amino-6-amidobiotinyl-pyridine (BAP) derivatives obtained by reductive
amination, and 6-(biotinyl)-aminocaproyl-hydrazide (BACH) derivatives which
have a longer spacer-arm. N -Glycan-BNAH and-BAP derivatives have, overall,
comparable reactivities with lectins which recognize N -glycan outer-arms
or the trimannosyl core, but only BNAH and BACH derivatives are bound by
lectins which recognize the non- reduced core. Moreover, with Pisum sativum
agglutinin (PSA) which additionally requires the fucosyl- N-
glycan-asparaginyl core for high affinity binding, the immobilized BNAH
derivative (which is an alanine hydrazide beta-glycoside) can substitute
for the natural beta- glycosylasparaginyl core, whereas the BACH derivative
(aminocaproyl- hydrazide-beta-glycoside) is less effective. BNAH is a
derivatization reagent of choice, therefore, for solid phase
carbohydrate-binding experiments with immobilized N -glycans.
相似文献
94.
Rossi MS; Barrio E; Latorre A; Quezada-Diaz JE; Hasson E; Moya A; Fontdevila A 《Molecular biology and evolution》1996,13(2):314-323
Both original and colonizer populations of Drosophila buzzatii have been
analyzed for mtDNA restriction polymorphisms. Most of the mtDNA nucleotide
variation in original populations of NW Argentina can be explained by
intrapopulation diversity and only a small fraction can be accounted for by
between-population diversity. Similar results are obtained using either the
estimated number of nucleotide substitutions per site or considering each
restriction site as a locus. Colonizer populations of the Iberian Peninsula
are monomorphic and show only the most common haplotype from the original
populations. Under the infinite island model and assuming that populations
are in equilibrium, fixation indices indicate enough gene flow to explain
why the populations are not structured. Yet, the possibility exists that
populations have not reached an equilibrium after a founder event at the
end of the last Pleistocene glaciation. Tajima's test suggests that
directional selection and/or a recent bottleneck could explain the present
mtDNA differentiation. Considering the significant population structure
found for the chromosomal and some allozyme polymorphisms, the among-
population uniformity for mtDNA variability argues in favor of the
chromosomal and some allozyme polymorphisms being adaptive.
相似文献
95.
A Traboulsee A AL-Sabbagh R Bennett P Chang DKB Li the EVIDENCE Study Group the UBC MS/MRI Research Group 《BMC neurology》2008,8(1):11
Background
The EVIDENCE (EVidence of Interferon Dose-response: European North American Comparative Efficacy) study was an international, randomized, open-label, assessor-blinded, parallel-group study assessing the efficacy and tolerability of interferon (IFN) beta-1a, 44 mcg subcutaneously (sc) three times weekly (tiw), and IFN beta-1a, 30 mcg intramuscularly (im) once weekly (qw), in patients with relapsing-remitting multiple sclerosis (RRMS). The aim of this analysis was to assess whether reductions in T2 burden of disease (BOD) were greater for patients receiving IFN beta-1a, 44 mcg sc tiw, than for those treated with IFN beta-1a, 30 mcg im qw, and to assess the impact of neutralizing antibodies (NAbs). 相似文献96.
97.
Nitzan Soffer Marilyn E Brandt Adrienne MS Correa Tyler B Smith Rebecca Vega Thurber 《The ISME journal》2014,8(2):271-283
White plague (WP)-like diseases of tropical corals are implicated in reef decline worldwide, although their etiological cause is generally unknown. Studies thus far have focused on bacterial or eukaryotic pathogens as the source of these diseases; no studies have examined the role of viruses. Using a combination of transmission electron microscopy (TEM) and 454 pyrosequencing, we compared 24 viral metagenomes generated from Montastraea annularis corals showing signs of WP-like disease and/or bleaching, control conspecific corals, and adjacent seawater. TEM was used for visual inspection of diseased coral tissue. No bacteria were visually identified within diseased coral tissues, but viral particles and sequence similarities to eukaryotic circular Rep-encoding single-stranded DNA viruses and their associated satellites (SCSDVs) were abundant in WP diseased tissues. In contrast, sequence similarities to SCSDVs were not found in any healthy coral tissues, suggesting SCSDVs might have a role in WP disease. Furthermore, Herpesviridae gene signatures dominated healthy tissues, corroborating reports that herpes-like viruses infect all corals. Nucleocytoplasmic large DNA virus (NCLDV) sequences, similar to those recently identified in cultures of Symbiodinium (the algal symbionts of corals), were most common in bleached corals. This finding further implicates that these NCLDV viruses may have a role in bleaching, as suggested in previous studies. This study determined that a specific group of viruses is associated with diseased Caribbean corals and highlights the potential for viral disease in regional coral reef decline. 相似文献
98.
Judith Field Fernando Shahijanian Stephen Schibeci Australia New Zealand MS Genetics Consortium Laura Johnson Melissa Gresle Louise Laverick Grant Parnell Graeme Stewart Fiona McKay Trevor Kilpatrick Helmut Butzkueven David Booth 《PloS one》2015,10(6)
Human genetic and animal studies have implicated the costimulatory molecule CD40 in the development of multiple sclerosis (MS). We investigated the cell specific gene and protein expression variation controlled by the CD40 genetic variant(s) associated with MS, i.e. the T-allele at rs1883832. Previously we had shown that the risk allele is expressed at a lower level in whole blood, especially in people with MS. Here, we have defined the immune cell subsets responsible for genotype and disease effects on CD40 expression at the mRNA and protein level. In cell subsets in which CD40 is most highly expressed, B lymphocytes and dendritic cells, the MS-associated risk variant is associated with reduced CD40 cell-surface protein expression. In monocytes and dendritic cells, the risk allele additionally reduces the ratio of expression of full-length versus truncated CD40 mRNA, the latter encoding secreted CD40. We additionally show that MS patients, regardless of genotype, express significantly lower levels of CD40 cell-surface protein compared to unaffected controls in B lymphocytes. Thus, both genotype-dependent and independent down-regulation of cell-surface CD40 is a feature of MS. Lower expression of a co-stimulator of T cell activation, CD40, is therefore associated with increased MS risk despite the same CD40 variant being associated with reduced risk of other inflammatory autoimmune diseases. Our results highlight the complexity and likely individuality of autoimmune pathogenesis, and could be consistent with antiviral and/or immunoregulatory functions of CD40 playing an important role in protection from MS. 相似文献
99.
Angélica MS Firmo Mônica MP Tognella Saulo R Silva Raynner RRD Barboza Rômulo RN Alves 《Journal of ethnobiology and ethnomedicine》2012,8(1):1-12
Background
Blue Land Crab (Cardisoma guanhumi) is one of the most important crustacean species captured and commercialized in Brazil. Although this species is not considered to be threatened with extinction, populations of C. guanhumi are known to be rapidly diminishing due to heavy harvesting pressures and degradation of their natural habitats, highlighting the necessity of developing and implanting management and protection strategies for their populations. There have been no ethnozoological publications that have focused specifically on C. guanhumi, in spite of importance of this type of information for developing efficient management plans of resource utilization. So, the present work describes the ethnoecological aspects of the capture and commercialization of C. guanhumi by a fishing community in northeastern Brazil.Methods
Field work was carried out in the municipality of Mucuri, Bahia in Brazil, between the months of January and March/2011 through the use of open semi-structured interviews with all of the crustacean harvesters in city who acknowledged their work in capturing this species, totaling 12 interviewees. The informants were identified through the use of the "snowball" sampling technique. In addition to the interviews themselves, the "guided tour" technique and direct observations was employed.Results
According all the interviewees, the C. guanhumi is popularly called "guaiamum" and is collected in "apicum" zones. They recognize sexual dimorphism in the species based on three morphological characteristics and the harvesters also pointed two stages in the reproductive cycle during the year and another phase mentioned by the interviewees was ecdysis. All of the interviewed affirmed that the size and the quantities C. guanhumi stocks in Mucuri have been diminishing. All of the interviewees agreed that the species and other mangrove resources constituted their principal source of income. The harvesters dedicated three to five days a week to collect Blue Land Crabs and the principal technique utilized for capturing is a trap called a "ratoeira" (rat-trap).Conclusions
The results of the present work demonstrated that the community retains a vast and important volume of knowledge about C. guanhumi that could subsidize both scientific studies and the elaboration of viable management and conservation strategies for this species. 相似文献100.
Husain S Yildirim-Toruner C Rubio JP Field J;Southern MS Genetics Consortium Schwalb M Cook S Devoto M Vitale E 《PloS one》2008,3(7):e2653
Multiple sclerosis (MS) is an inflammatory demyelinating disease of the central nervous system of unknown etiology with both genetic and environmental factors playing a role in susceptibility. To date, the HLA DR15/DQ6 haplotype within the major histocompatibility complex on chromosome 6p, is the strongest genetic risk factor associated with MS susceptibility. Additional alleles of IL7 and IL2 have been identified as risk factors for MS with small effect. Here we present two independent studies supporting an allelic association of MS with polymorphisms in the ST8SIA1 gene, located on chromosome 12p12 and encoding ST8 alpha-N-acetyl-neuraminide alpha-2,8-sialyltransferase 1. The initial association was made in a single three-generation family where a single-nucleotide polymorphism (SNP) rs4762896, was segregating together with HLA DR15/DQ6 in MS patients. A study of 274 family trios (affected child and both unaffected parents) from Australia validated the association of ST8SIA1 in individuals with MS, showing transmission disequilibrium of the paternal alleles for three additional SNPs, namely rs704219, rs2041906, and rs1558793, with p = 0.001, p = 0.01 and p = 0.01 respectively. These findings implicate ST8SIA1 as a possible novel susceptibility gene for MS. 相似文献