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61.
We have previously described actin edge-bundles (AEBs) as cables of microfilaments lining the webbed edges of 3T3 cells (Zand and Albrecht-Buehler: Cell Motil. Cytoskeleton 13:195-211, 1989). We have suggested that AEBs, along with their cell-substratum adhesions, resist cortical tension and prevent the collapse of cytoplasm towards the nucleus. In this paper, we report several stages of AEB disassembly and re-formation induced by the following micro-manipulations: (1) Scoring of the webbed edge of a 3T3 cells with a micro-needle. As a result the sides of the score retracted and the severed AEB appeared to disassemble down to its terminal adhesion points. The retraction stopped after 20-40 seconds and the cells formed a webbed edge with large curvature. Over a period of 20-80 minutes, the new web decreased in length and depth, until it regained its approximate original shape. (2) Bending of cell processes at acute angles. As a result the processes moved until they projected at right angles to the side of the cell and formed new webs gradually expanded their area. In both cases, the nascent webs were lined by actin edge-bundles. 相似文献
62.
Gotsman M Dusa C Nassar H Hasin Y Lotan C Rozenman Y 《International journal of cardiovascular interventions》1999,2(3):187-190
The Cutting Balloon consists of a standard balloon dilatation catheter with four microtome-sharp blades that incise the plaque and minimize arterial wall trauma. It was used in 31 patients; nine had calcified arteries, ten had non-compliant lesions, three had in-stent restenosis and nine had aorto-ostial lesions. Seventeen lesions were predilated, 28 were post-dilated and 18 required stent implantation. The procedure was very effective in aorto-ostial lesions, non-compliant lesions that were not responsive to high-pressure balloon dilatation, and was partially successful in calcified arteries. It has a very specific niche in selected lesions. 相似文献
63.
Zhang F Wang MH Wang JS Zand B Gopal VR Falck JR Laniado-Schwartzman M Nasjletti A 《American journal of physiology. Heart and circulatory physiology》2004,287(3):H1089-H1095
Cytochrome P-450-4A1 (CYP4A1) is an omega-hydroxylase that catalyzes the metabolism of arachidonic acid to 20-hydroxyeicosatetraenoic acid (20-HETE). The goal of this study was to determine the vasomotor consequences of vascular overexpression of CYP4A1. Isolated rat gracilis muscle arterioles transfected ex vivo with an expression plasmid containing CYP4A1 cDNA expressed more CYP4A protein than vessels transfected with the control plasmid. In arterioles pressurized to 80 mmHg, the internal diameter of vessels transfected with CYP4A1 cDNA (55 +/- 3 microm) was surpassed (P < 0.05) by that of vessels transfected with control plasmid (97 +/- 4 microm). Treatment with a CYP4A inhibitor (N-methylsulfonyl-12,12-dibromododec-11-enamide; DDMS) or with an antagonist of 20-HETE actions [20-hydroxyeicosa-6(Z),15(Z)-dienoic acid; 20-HEDE] elicited robust dilation of arterioles transfected with CYP4A1 cDNA, whereas the treatment had little or no effect in vessels transfected with control plasmid. Examination of the intraluminal pressure-internal diameter relationship revealed that pressure increments over the range of 40-100 mmHg elicited a more intense (P < 0.05) myogenic constrictor response in arterioles transfected with CYP4A1 cDNA than in those with control plasmid. Arterioles transfected with CYP4A1 cDNA also displayed enhanced sensitivity to the constrictor action of phenylephrine. Treatment with DDMS or 20-HEDE greatly attenuated the constrictor responsiveness to both constrictor stimuli in vessels overexpressing CYP4A1, whereas the treatment had much less effect in control vessels. These data suggest that CYP4A1 overexpression promotes constriction of gracilis muscle arterioles by intensifying the responsiveness of vascular smooth muscle to constrictor stimuli. This effect of CYP4A1 overexpression appears to be mediated by a CYP4A1 product. 相似文献
64.
Zand L Qiang F Roskelley CD Leung PC Auersperg N 《In vitro cellular & developmental biology. Animal》2003,39(3-4):178-182
Summary The main form of fibronectin (FN) encountered by tumor cells in vivo is cellular FN (cFN), which differs structurally and
functionally from the commonly used plasma FN (pFN). We compared the effects of cFN and pFN on the ovarian carcinoma lines
OVCAR-3 and SKOV-3 and on cultures of normal ovarian surface epithelium, which is the precursor of the epithelial ovarian
carcinomas. Ovarian surface epithelial cells and SKOV-3 cells attached and spread faster on cFN than on pFN. On cFN, SKOV-3
migration was enhanced compared with pFN or plastic. In a matrigel transfilter assay, cFN strongly inhibited SKOV-3 invasion,
whereas pFN did not. In contrast to SKOV-3, OVCAR-3 cells adhered faster on FN than on plastic but did not discriminate between
cFN and pFN, and they did not migrate or invade matrigel either with or without FN. In both carcinoma lines, proliferation
was unaffected by either FN. The results show profound differences in the responses to cFN and pFN by two invasive ovarian
carcinoma lines. Because cFN is the main type that cancer cells encounter in vivo, extrapolations from culture data to in
vivo events should preferably be based on studies using this form of FN. 相似文献
65.
Lucotte GL;French MS Consortium 《Genetic counseling (Geneva, Switzerland)》2002,13(2):133-138
To identify the chromosomal localizations of the multiple sclerosis (MS) genes, we conducted a genomewide linkage analysis using eighteen affected families. A MS gene is linked to markers located in the 19q13.3 region (multipoint lod-score = 2.1). Apolipoprotein E (ApoE) gene, located in this region, is an excellent candidate gene for MS because the ApoEe4 allele is acting as a severity allele in the disease. 相似文献
66.
67.
Substitution bias, rapid saturation, and the use of mtDNA for nematode systematics 总被引:13,自引:0,他引:13
Only relatively recently have researchers turned to molecular methods for
nematode phylogeny reconstruction. Thus, we lack the extensive literature
on evolutionary patterns and phylogenetic usefulness of different DNA
regions for nematodes that exists for other taxa. Here, we examine the
usefulness of mtDNA for nematode phylogeny reconstruction and provide data
that can be used for a priori character weighting or for parameter
specification in models of sequence evolution. We estimated the
substitution pattern for the mitochondrial ND4 gene from intraspecific
comparisons in four species of parasitic nematodes from the family
Trichostrongylidae (38-50 sequences per species). The resulting pattern
suggests a strong mutational bias toward A and T, and a lower
transition/transversion ratio than is typically observed in other taxa. We
also present information on the relative rates of substitution at first,
second, and third codon positions and on relative rates of saturation of
different types of substitutions in comparisons ranging from intraspecific
to interordinal. Silent sites saturate extremely quickly, presumably owing
to the substitution bias and, perhaps, to an accelerated mutation rate.
Results emphasize the importance of using only the most closely related
sequences in order to infer patterns of substitution accurately for
nematodes or for other taxa having strongly composition-biased DNA. ND4
also shows high amino acid polymorphism at both the intra- and
interspecific levels, and in higher level comparisons, there is evidence of
saturation at variable amino acid sites. In general, we recommend using
mtDNA coding genes only for phylogenetics of relatively closely related
nematode species and, even then, using only nonsynonymous substitutions and
the more conserved mitochondrial genes (e.g., cytochrome oxidases). On the
other hand, the high substitution rate in genes such as ND4 should make
them excellent for population genetics studies, identifying cryptic
species, and resolving relationships among closely related congeners when
other markers show insufficient variation.
相似文献
68.
Differentiation-associated modulation of heparan sulfate structure and function in CaCo-2 colon carcinoma cells 总被引:3,自引:2,他引:1
Salmivirta M; Safaiyan F; Prydz K; Andresen MS; Aryan M; Kolset SO 《Glycobiology》1998,8(10):1029-1036
Heparan sulfate species expressed by different cell and tissue types differ
in their structural and functional properties. Limited information is
available on differences in regulation of heparan sulfate biosynthesis
within a single tissue or cell population under different conditions. We
have approached this question by studying the effect of cell
differentiation on the biosynthesis and function of heparan sulfate in
human colon carcinoma cells (CaCo-2). These cells undergo spontaneous
differentiation in culture when grown on semipermeable supports; the
differentiated cells show phenotypic similarity to small intestine
enterocytes. Metabolically labeled heparan sulfate was isolated from the
apical and basolateral media from cultures of differentiated and
undifferentiated cells. Compositional analysis of disaccharides, derived
from the contiguous N-sulfated regions of heparan sulfate, indicated a
greater proportion of 2-O- sulfated iduronic acid units and a smaller
amount of 6-O-sulfated glucosamine units in differentiated than in
undifferentiated cells. By contrast, the overall degree of sulfation, the
chain length and the size distribution of the N-acetylated regions were
similar regardless the differentiation status of the cells. The structural
changes were found to affect the binding of heparan sulfate to the long
isoform of platelet-derived growth factor A chain but not to fibroblast
growth factor 2. These findings show that heparan sulfate structures change
during cell differentiation and that heparan sulfate-growth factor
interactions may be affected by such changes.
相似文献
69.
Methionine had been observed to interact with two principal transport systems for amino acids in mammalian cells, the A and L systems. The present study of methionine transport and of exchange processes through system A arose in the course of a study to define the specificity of a transinhibition effect caused by cysteine.Methionine uptake through two transport systems in the S37 cell was confirmed by the occurrence of a biphasic double-reciprocal plot for labeled methionine uptake. Preloading cells with methionine stimulated labeled histidine uptake through both systems A and L. Efflux of labeled methionine from cells was stimulated by histidine in a biphasic manner, so that both systems A and L can be used for exchange when methionine is the intracellular amino acid. Aminocycloheptanecarboxylic acid elicited exchange efflux of labeled methionine only through system L. α-Aminoisobutyric acid and both stimulated efflux of labeled from S37 cells. These findings are interpreted a showing that transport system A is capable of functioning as an exchange system depending upon the identity of intracellular and extracellular substrates available. 相似文献
70.
Kemmer D Huang Y Shah SP Lim J Brumm J Yuen MM Ling J Xu T Wasserman WW Ouellette BF 《Genome biology》2005,6(12):R106
We developed Ulysses as a user-oriented system that uses a process called Interolog Analysis for the parallel analysis and
display of protein interactions detected in various species. Ulysses was designed to perform such Interolog Analysis by the
projection of model organism interaction data onto homologous human proteins, and thus serves as an accelerator for the analysis
of uncharacterized human proteins. The relevance of projections was assessed and validated against published reference collections.
All source code is freely available, and the Ulysses system can be accessed via a web interface . 相似文献