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排序方式: 共有378条查询结果,搜索用时 31 毫秒
101.
Parathath S Sahoo D Darlington YF Peng Y Collins HL Rothblat GH Williams DL Connelly MA 《The Journal of biological chemistry》2004,279(24):24976-24985
Scavenger receptor BI, SR-BI, is a physiologically relevant receptor for high density lipoprotein (HDL) that mediates the uptake of cholesteryl esters and delivers them to a metabolically active membrane pool where they are subsequently hydrolyzed. A previously characterized SR-BI mutant, A-VI, with an epitope tag inserted into the extracellular domain near the C-terminal transmembrane segment, revealed a separation-of-function between SR-BI-mediated HDL cholesteryl ester uptake and cholesterol efflux to HDL, on one hand, and cholesterol release to small unilamellar phospholipid vesicle acceptors and an increased cholesterol oxidase-sensitive pool of membrane free cholesterol on the other. To further elucidate amino acid residues responsible for this separation-of-function phenotype, we engineered alanine substitutions and point mutations in and around the site of epitope tag insertion, and tested these for various cholesterol transport functions. We found that changing amino acid 420 from glycine to histidine had a profound effect on SR-BI function. Despite the ability to mediate selective HDL cholesteryl ester uptake, the G420H receptor had a greatly reduced ability to: 1) enlarge the cholesterol oxidase-sensitive pool of membrane free cholesterol, 2) mediate cholesterol efflux to HDL, even at low concentrations of HDL acceptor where binding-dependent cholesterol efflux predominates, and 3) accumulate cholesterol mass within the cell. Most importantly, the G420H mutant was unable to deliver the HDL cholesteryl ester to a metabolically active membrane compartment for efficient hydrolysis. These observations have important implications regarding SR-BI function as related to its structure near the C-terminal transmembrane domain. 相似文献
102.
Large-restriction-fragment polymorphism analysis of Mycobacterium chelonae and Mycobacterium terrae isolates 总被引:3,自引:0,他引:3
Vanitha JD Venkatasubramani R Dharmalingam K Paramasivan CN 《Applied and environmental microbiology》2003,69(7):4337-4341
Mycobacterium chelonae and Mycobacterium terrae were reported to be frequently present in the environment of the Mycobacterium bovis BCG trial area in south India. Six isolates of M. chelonae and four isolates of M. terrae obtained from different sources in this area were analyzed by pulsed-field gel electrophoresis (PFGE) to examine large-restriction-fragment (LRF) polymorphism using the chromosomal DNA digested with DraI and XbaI restriction enzymes. With the exception of one isolate of M. terrae, DNA from all other isolates could be digested with DraI and XbaI and resulted in separable fragments. Visual comparison of the LRFs showed a unique pattern for each of the isolates tested. A computer-assisted dendrogram of the percent similarity demonstrated a high degree of genetic diversity in this group of isolates. This study demonstrates that species of nontuberculous mycobacteria, particularly M. chelonae and M. terrae, can be successfully typed by their LRF pattern using PFGE, which does not require species-specific DNA probes. 相似文献
103.
A globin in the nucleus! 总被引:15,自引:0,他引:15
Geuens E Brouns I Flamez D Dewilde S Timmermans JP Moens L 《The Journal of biological chemistry》2003,278(33):30417-30420
104.
Design of a partial peptide mimetic of anginex with antiangiogenic and anticancer activity 总被引:5,自引:0,他引:5
Mayo KH Dings RP Flader C Nesmelova I Hargittai B van der Schaft DW van Eijk LI Walek D Haseman J Hoye TR Griffioen AW 《The Journal of biological chemistry》2003,278(46):45746-45752
Based on structure-activity relationships of the angiostatic beta-sheet-forming peptide anginex, we have designed a mimetic, 6DBF7, which inhibits angiogenesis and tumor growth in mice. 6DBF7 is composed of a beta-sheet-inducing dibenzofuran (DBF)-turn mimetic and two short key amino acid sequences from anginex. This novel antiangiogenic molecule is more effective in vivo than parent anginex. In a mouse xenograft model for ovarian carcinoma, 6DBF7 is observed to reduce tumor growth by up to 80%. It is suggested that the activity is based on antiangiogenesis, because in vitro tube formation is inhibited, and because treatment of tumor-bearing mice led to a significant reduction in microvessel density within the tumor. This partial peptide mimetic is the first endothelial cell-specific molecule designed as a substitute for an angiostatic inhibitory peptide. 相似文献
105.
Apolipophorin III (ApoLp-III) from the Sphinx moth, Manduca sexta, is an 18kDa protein that binds reversibly to hydrophobic surfaces generated on metabolizing lipoprotein particles. It is comprised of amphipathic alpha-helices (H1-H5) organized in an up-and-down topology forming a helix bundle in the lipid-free state. Upon interaction with lipids, apoLp-III has been proposed to undergo a dramatic conformational change, involving helix bundle opening about putative hinge loops such that H1, H2 and H5 move away from H3 and H4. In the present study, we examine the relative spatial disposition of H1 and H5 on discoidal phospholipid complexes and spherical lipoproteins. Cysteine residues were engineered at position 8 in H1 and/or at position 138 in H5 in apoLp-III (which otherwise lacks Cys) yielding A8C-, A138C- and A8C/A138C-apoLp-III. Tethering of H1 and H5 by a disulfide bond between A8C and A138C abolished the ability of apoLp-III to transform phospholipid vesicles to discoidal particles, or to interact with lipoproteins, demonstrating that these helices are required to reposition during lipid interaction. Site-specific labeling of A8C/A138C-apoLp-III with N-(1-pyrene)maleimide in the lipid-free state resulted in intramolecular pyrene "excimer" fluorescence emission indicative of spatial proximity between these sites. Upon association with dimyristoylphosphatidylcholine (DMPC) discoidal complexes, the intramolecular excimer was replaced by intermolecular excimer fluorescence due to proximity between pyrene moieties on A8C and A138C in neighboring apoLp-III molecules on the discoidal particle. No excimer emission was observed in the case of pyrene-A8C-apoLp-III/DMPC or pyrene-A138C-apoLp-III/DMPC complexes. However, equimolar mixing of the two labeled single-cysteine mutants prior to disc formation resulted in excimer emission. In addition, intramolecular pyrene excimer formation was diminished upon binding of pyrene-A8C/A138C-apoLp-III to spherical lipoproteins. The data are consistent with repositioning of H1 away from H5 upon encountering a lipid surface, resulting in an extended conformation of apoLp-III that circumscribes the discoidal bilayer particle. 相似文献
106.
Miguel Viribay Raúl Ferreira Blén Perai Daisy Bello Christopher J. Ward José Dávalos Carlos Valle Peter C. Harris Dora Méndez del Castillo Felipe Moreno José L. San Millan 《Human genetics》1994,94(4):432-436
We report on linkage analysis and haplotype characterization in 12 Cuban families with autosomal dominant polycystic kidney disease (ADPK) using PKD1-linked markers. They included both standard restriction fragment length polymorphisms (26.6., BLu24, and pGGGl) as well as microsatellite polymorphisms (CW2, 16AC2.5, and SM6). All of the examined families were fully informative for genetic diagnosis and no evidence of unlinked families was found. Analysis of two recombination events places PKD1 distal to the marker BLu24 and reduces the size of the region likely to contain the disease gene by approximately 300 kb. The allele frequencies of each marker were similar in the ADPKD and normal populations. 相似文献
107.
Forty-six strains ofSimonsiella—large, Gram-negative, aerobic, multicellular filamentous, gliding bacteria from the oral cavities of cats, dogs, sheep, and
humans—were grown under various environmental conditions to elucidate features of gliding motility in the genus. Under standard
growth conditions on bovine serum-tryptic soy-yeast extract (BSTSY) agar at 37°C, few strains glided. Nongliding strains displayed
edges of microscopic colonies ranging from entire to rhizoid (filamentous outgrowth). Gliding strains displayed motility on
agar in individual, often well-separated filaments, forming etched tracks in the agar. In some strains, gliding on agar led
to the formation of satellite colonies, suggesting that motility is a possible mechanism for sustaining growth. Gliding was
often pronounced in regions of heavy growth bordering on unoccupied agar surfaces, suggesting that motility might be triggered
by growth metabolite accumulations, but, also, might require certain levels of fresh nutrients. Motility rates of 4- to 12-h-old
cultures of selected strains in BSTSY broth or on BSTSY plus 0.5% agar (measured in sealed slide preparations held at approximately
37°C) ranged from 5 to 23.8 μm/min. Rate variations, obtained for the same as well as different trials, would be expected
due to variations in oxygen tension and in metabolite and nutrient concentrations on agar sealed under glass. 相似文献
108.
Herta M. Vickrey Daisy S. McCann 《In vitro cellular & developmental biology. Plant》1978,14(3):312-316
Summary The effect of temperature on inorganic mercury toxicity was investigated using kidney tissue culture systems. The relative
susceptibility of rabbit (homeothermic) kidney to mercury intoxication was compared to that of Coho salmon (poikilothermic)
kidney over temperature ranges consistent with the habitat of each of the two species. It was demonstrated that susceptibility
to mercury toxicity is species dependent; that is, the rabbit kidney cells tolerated higher mercury concentrations in the
medium than did the fish-derived cells. Within a given species, susceptibility to mercury toxicity was temperature dependent.
Decreasing the temperature increased the toxicity of mercury to cultures of rabbit kidney cells, whereas decreasing temperatures
decreased the effect of mercury toxicity on the salmon kidney cells. As a consequence, fish taken from arctic waters are liable
to be more toxic when introduced into mammalian food chains. Albumin was shown to act as a protective agent in vitro against
inorganic mercury toxicity.
Research was supported in part by the University of Victoria Faculty Grant No. 08-869 and a Medical Staff Research and Education
Fund Grant from Wayne County General Hospital, Eloise, Michigan. 相似文献
109.
Dorsal-ventral differentiation in Simonsiella and other aspects of its morphology and ultrastructure 总被引:1,自引:0,他引:1
The morphology and ultrastructure of the aerobic, Gram-negative multicellular-filamentous bacteria of the genus Simonsiella were investigated by scanning and transmission electron microscopy. The flat, ribbon-shaped, multicellular filaments show dorsal-ventral differentiation with respect to their orientations to solid substrata. The dorsal surface, orientated away from the substrate, is convex and possesses an unstructured capsule. The ventral surface, on which the organisms adhere and glide, is concave and has an extracellular layer with fibrils extending at right angles from the cell wall. The cytoplasm in the ventral region contains a proliferation of intracytoplasmic membranes and few ribosomes in comparison to the cytoplasm in other parts of the cell. Centripetal cell wall formation is asymmetrical and commences preferentially in the ventral region. Quantitative differences in morphology and cytology exist among selected Simonsiella strains. Functional aspects of this dorsalventral differentiation are discussed with respect to the colonization and adherence of Simonsiella to mucosal squamous epithelial cells in its ecological habitat, the oral cavities of warm-blooded vertebrates.List of Abbreviations SEM
scanning electron microscope
- TEM
transmission electron microscope 相似文献
110.
Daisy Hilse Dwyer 《Dialectical Anthropology》1979,4(4):309-320
Conclusion The anthropology of law works best through the use of the holistic approach that Hoebel recommended in the early stages of the subdiscipline. That approach includes the study of trouble cases, of patterns of actual law-related behavior, and of abstract rules or principles, the last being not the least among them. The quest should ideally be joined, however, so as to generate data that lend themselves to cross-cultural comparison and the formulation of politico-legal principles of a general sort, a goal which numerous anthropologists of law have already espoused in their work. But as Smith and Roberts caution, this is particularly difficult with regard to substantive law content, because substantive law is a particularly culture bound domain: there is considerable variability from society to society in its specific content. The structural comparison of substantive law notions as they occur within the boundaries of particular societies, by contrast, presents one fruitful alternative approach, one which carefully reflects the realities of intergroup politics. Through a political analysis of variability in cognitive models of law can better be seen as a reflection of, and an underpinning to, the socio-economic base that correlates with it.Nader indirectly calls attention to the fact that the law realm is best viewed from an explicitly political vantage. She notes that a lack of interest in substantive law has been accompanied by a relative loss of interest in political development, two tendencies which Koch also cites. But the very element of political developmental dynamics, as has been seen, forms a crucial component in understanding the variability in substantive law models and, more broadly, law's ideational side (see Moore ). Polities that wield considerable power potentials can generate and accomodate co-occurring non-isomorphic law models, and, indeed, it seems advantageous from the elite vantage for them to do so. With respect to their political strategies, societies with more modest power potentials also seem to avail themselves of such discordances to some degree. The result is a complex involvement with substantive law in most societies, and certainly at the state level.Daisy Hilse Dwyer is Assistant Professor of Anthropology at Columbia University.
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