全文获取类型
收费全文 | 134篇 |
免费 | 8篇 |
出版年
2021年 | 2篇 |
2020年 | 2篇 |
2019年 | 1篇 |
2018年 | 1篇 |
2017年 | 2篇 |
2016年 | 3篇 |
2015年 | 4篇 |
2014年 | 3篇 |
2013年 | 4篇 |
2012年 | 5篇 |
2011年 | 2篇 |
2010年 | 6篇 |
2009年 | 7篇 |
2008年 | 3篇 |
2007年 | 1篇 |
2006年 | 1篇 |
2005年 | 3篇 |
2003年 | 3篇 |
2001年 | 4篇 |
2000年 | 1篇 |
1999年 | 7篇 |
1998年 | 3篇 |
1996年 | 4篇 |
1995年 | 3篇 |
1994年 | 2篇 |
1993年 | 2篇 |
1992年 | 3篇 |
1991年 | 3篇 |
1990年 | 1篇 |
1989年 | 2篇 |
1988年 | 1篇 |
1987年 | 1篇 |
1986年 | 5篇 |
1985年 | 1篇 |
1984年 | 1篇 |
1983年 | 1篇 |
1982年 | 3篇 |
1981年 | 7篇 |
1980年 | 1篇 |
1979年 | 10篇 |
1978年 | 11篇 |
1977年 | 4篇 |
1975年 | 1篇 |
1974年 | 5篇 |
1973年 | 1篇 |
1969年 | 1篇 |
排序方式: 共有142条查询结果,搜索用时 578 毫秒
71.
72.
The in vivo formation of fibrillar proteinaceous deposits called amyloid is associated with more than 40 serious human diseases, collectively referred to as protein deposition diseases. In many cases the amyloid deposits are extracellular and are found associated with newly identified abundant extracellular chaperones (ECs). Evidence is presented suggesting an important regulatory role for ECs in amyloid formation and disposal in the body. A model is presented which proposes that, under normal conditions, ECs stabilize extracellular misfolded proteins by binding to them, and then guide them to specific cell receptors for uptake and subsequent degradation. Thus ECs and their receptors may be critical parts of a quality control system to protect the body against dangerously hydrophobic proteins/peptides. However, it also appears possible that in the presence of a high molar excess of misfolded protein, such as might occur during disease, the limited amounts of ECs available may actually exacerbate pathology. Further advances in understanding of the mechanisms that control extracellular protein folding are likely to identify new strategies for effective disease therapies. 相似文献
73.
The acute phase protein haptoglobin is a mammalian extracellular chaperone with an action similar to clusterin 总被引:6,自引:0,他引:6
Yerbury JJ Rybchyn MS Easterbrook-Smith SB Henriques C Wilson MR 《Biochemistry》2005,44(32):10914-10925
Haptoglobin (Hp) is an acidic glycoprotein present in most body fluids of humans and other mammals. Although the functions of Hp are not yet fully understood, the available evidence indicates that it is likely to play an important role in suppressing inflammatory responses. Some earlier work suggested that Hp might be a newly identified member of a small group of extracellular chaperones found at significant levels in human body fluids. Previously, the only well-characterized member of this group was clusterin, which shares functional similarities with the small heat-shock proteins. We report here that Hp specifically inhibited the precipitation of a variety of proteins induced by either heat or oxidation, including proteins in unfractionated human serum. We also show that, like clusterin, Hp (i) inhibits the precipitation of stressed proteins by forming solubilized high molecular weight complexes with them, (ii) cannot protect enzymes from heat-induced loss of function, and (iii) lacks ATPase activity and the ability to independently refold proteins following stresses. Furthermore, we show that Hp has maximum chaperone activity at mildly alkaline pH and, unlike clusterin, does not undergo significant changes in oligomerization state coincident with pH-induced changes in chaperone activity. Our results raise the possibility that Hp may exert an anti-inflammatory action in vivo by inhibiting the inappropriate self-association of "damaged" (misfolded) extracellular proteins. 相似文献
74.
Comparison of the evolutionary dynamics of symbiotic and housekeeping loci: a case for the genetic coherence of rhizobial lineages 总被引:6,自引:1,他引:5
In prokaryotes, lateral gene transfer across chromosomal lineages may be
mediated by plasmids, phages, transposable elements, and other accessory
DNA elements. However, the importance of such transfer and the evolutionary
forces that may restrict gene exchange remain largely unexplored in native
settings. In this study, tests of phylogenetic congruence are employed to
explore the range of horizontal transfer of symbiotic (sym) loci among
distinct chromosomal lineages of native rhizobia, the nitrogen-fixing
symbiont of legumes. Rhizobial strains isolated from nodules of several
host plant genera were sequenced at three loci: symbiotic nodulation genes
(nodB and nodC), the chromosomal housekeeping locus glutamine synthetase II
(GSII), and a portion of the 16S rRNA gene. Molecular phylogenetic analysis
shows that each locus generally subdivides strains into the same major
groups, which correspond to the genera Rhizobium, Sinorhizobium, and
Mesorhizobium. This broad phylogenetic congruence indicates a lack of
lateral transfer across major chromosomal subdivisions, and it contrasts
with previous studies of agricultural populations showing broad transfer of
sym loci across divergent chromosomal lineages. A general correspondence of
the three rhizobial genera with major legume groups suggests that host
plant associations may be important in the differentiation of rhizobial nod
and chromosomal loci and may restrict lateral transfer among strains. The
second major result is a significant incongruence of nod and GSII
phylogenies within rhizobial subdivisions, which strongly suggests
horizontal transfer of nod genes among congenerics. This combined evidence
for lateral gene transfer within, but not between, genetic subdivisions
supports the view that rhizobial genera are "reproductively isolated" and
diverge independently. Differences across rhizobial genera in the
specificity of host associations imply that the evolutionary dynamics of
the symbiosis vary considerably across lineages in native settings.
相似文献
75.
76.
Interactions of Photobleaching and Inorganic Nutrients in Determining Bacterial Growth on Colored Dissolved Organic Carbon 总被引:8,自引:0,他引:8
Abstract Bacteria are key organisms in the processing of dissolved organic carbon (DOC) in aquatic ecosystems. Their growth depends on both organic substrates and inorganic nutrients. The importance of allochthonous DOC, usually highly colored, as bacterial substrate can be modified by photobleaching. In this study, we examined how colored DOC (CDOC) photobleaching, and phosphorus (P) and nitrogen (N) availability, affect bacterial growth. Five experiments were conducted, manipulating nutrients (P and N) and sunlight exposure. In almost every case, nutrient additions had a significant, positive effect on bacterial abundance, production, and growth efficiency. Sunlight exposure (CDOC photobleaching) had a significant, positive effect on bacterial abundance and growth efficiency. We also found a significant, positive interaction between these two factors. Thus, bacterial use of CDOC was accelerated under sunlight exposure and enhanced P and N concentrations. In addition, the accumulation of cells in sunlight treatments was dependent on nutrient availability. More photobleached substrate was converted into bacterial cells in P- and N-enriched treatments. These results suggest nutrient availability may affect the biologically-mediated fate (new biomass vs respiration) of CDOC. 相似文献
77.
78.
79.
80.