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91.
Brendan P. Flynn Amit P. Bhole Nima Saeidi Melody Liles Charles A. DiMarzio Jeffrey W. Ruberti 《PloS one》2010,5(8)
Background
Collagen, a triple-helical, self-organizing protein, is the predominant structural protein in mammals. It is found in bone, ligament, tendon, cartilage, intervertebral disc, skin, blood vessel, and cornea. We have recently postulated that fibrillar collagens (and their complementary enzymes) comprise the basis of a smart structural system which appears to support the retention of molecules in fibrils which are under tensile mechanical strain. The theory suggests that the mechanisms which drive the preferential accumulation of collagen in loaded tissue operate at the molecular level and are not solely cell-driven. The concept reduces control of matrix morphology to an interaction between molecules and the most relevant, physical, and persistent signal: mechanical strain.Methodology/Principal Findings
The investigation was carried out in an environmentally-controlled microbioreactor in which reconstituted type I collagen micronetworks were gently strained between micropipettes. The strained micronetworks were exposed to active matrix metalloproteinase 8 (MMP-8) and relative degradation rates for loaded and unloaded fibrils were tracked simultaneously using label-free differential interference contrast (DIC) imaging. It was found that applied tensile mechanical strain significantly increased degradation time of loaded fibrils compared to unloaded, paired controls. In many cases, strained fibrils were detectable long after unstrained fibrils were degraded.Conclusions/Significance
In this investigation we demonstrate for the first time that applied mechanical strain preferentially preserves collagen fibrils in the presence of a physiologically-important mammalian enzyme: MMP-8. These results have the potential to contribute to our understanding of many collagen matrix phenomena including development, adaptation, remodeling and disease. Additionally, tissue engineering could benefit from the ability to sculpt desired structures from physiologically compatible and mutable collagen. 相似文献92.
93.
Alché LE Ferek GA Meo M Coto CE Maier MS 《Zeitschrift für Naturforschung. C, Journal of biosciences》2003,58(3-4):215-219
Bioassay guided purification of the ethyl acetate extract of leaves of Melia azedarach led to the isolation of the limonoid 1-cinnamoyl-3,11-dihydroxymeliacarpin, which showed IC50 values of 6 microM and 20 microM for vesicular stomatitis (VSV) and herpes simplex (HSV-1) viruses, respectively. Its structure was established by spectroscopic methods. 相似文献
94.
Assad JA 《Current opinion in neurobiology》2003,13(2):194-197
Flexible control of behavior requires the selective processing of task-relevant sensory information and the appropriate linkage of sensory input to action. A great deal of evidence suggests a central role for the parietal cortex in these functions. Recent results from neurophysiological studies in non-human primates and neuroimaging experiments in humans illuminate the importance of parietal cortex for attention, and suggest how parietal neurons might allow the dynamic representation of behaviorally relevant information. 相似文献
95.
Serious enteric and extra-intestinal infections with Salmonella typhimurium are very common in many human populations. Phagocytosis is the main defense mechanism against this bacterium; however, the unique structure of S. typhimurium lipopolysaccharide (LPS) makes it resistant to opsonization by complement components. In the present study, the S. typhimurium LPS O-chain was purified and conjugated with tetanus toxoid and the effects of the conjugated vaccine (O-specific polysaccharide tetanus toxoid (O-SP-TT)) on induction of specific antibodies were investigated in a mouse model. In vitro assays measuring phagocytosis in the presence of opsonizing antibodies were performed. Three subcutaneous injections of the O-SP-TT conjugate conferred protection against the intraperitoneal challenge with S. typhimurium and the LD50 was greater for immunized animals than for controls. The mean number of ingested S. typhimirium / mouse peritoneal cell in the presence of sera obtained from immunized mice with purified O-chain, O-SP-TT conjugate, heat-killed bacteria, and negative control were 6.96, 14.24, 15.96, and 6.67, respectively. In summary, we developed an O-SP-TT conjugate that induced opsonizing antibodies that increased phagocytosis, as determined by in vitro assays. In addition, chemiluminescence results, an indicator of oxidative burst, indicated that peritoneal cells respond better to live S. typhimurium cells in the presence of sera obtained from O-SP-TT conjugate immunized mice. 相似文献
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97.
Sopontammarak S Aliharoob A Ocampo C Arcilla RA Gupta MP Gupta M 《Cell biochemistry and biophysics》2005,43(1):61-76
Chronic pressure overload (PO) and volume overload (VO) result in morphologically and functionally distinct forms of myocardial
hypertrophy. However, the molecular mechanism initiating these two types of hypertrophy is not yet understood. Data obtained
from different cell types have indicated that the mitogen-activated protein kinases (MAPKs) comprising c-Jun NH2-terminal kinase (JNK), extracellular signal-regulated kinase (ERK), and p38 play an important role in transmitting signals
of stress stimuli to elicit the cellular response. We tested the hypothesis that early induction of MAPKs differs in two types
of overload on the heart and associates with distinct expression of hypertrophic marker genes, namely ANF, α-myosin heavy chain (α-MHC), and β-MHC. In rats, VO was induced by aortocaval shunt and PO by constriction of the abdominal aorta. The PO animals were further divided
into two groups depending on the severity of the constriction, mild (MPO) and severe pressure overload (SPO), having 35 and
85% aortic constriction, respectively. Early changes in MAPK activity (2–120 min and 1 to 2 d) were analyzed by the in vitro
kinase assay using kinase-specific antibodies for p38, JNK, and ERK2. The change in expression of hypertrophy marker genes
was examined by Northern blot analysis. In VO hypertrophy, the activity of p38 was markedly increased (10-fold), without changing
the activity of ERK and JNK. However, during PO hypertrophy, the activity of JNK was significantly increased (two-to sixfold)
and depended on the severity of the load. The activity of p38 was not changed in MPO hypertrophy, whereas it was slightly
elevated (50%) in hearts with SPO. Similarly, ERK activity was not changed in hearts with MPO, but a transient rise in activity
was observed in hearts with SPO. The expression of ANF and β-MHC genes was elevated in both PO and VO hypertrophy; however, this change was much greater in hearts subjected to PO than VO
hypertrophy. α-MHC expression was downregulated in PO but remained unchanged in VO hypertrophy hearts. Thus, these results demonstrate differential
activation of MAPKs in two types of cardiac hypertrophy and this, in part, may contribute to differential expression of cardiac
muscle gene expression, giving rise to unique cardiac phenotype associated with different hemodynamic overloads. 相似文献
98.
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100.
Omid Teymournejad Ashraf Mohabati Mobarez Zuhair Mohammad Hassan Shokoofe Noori Seyed Mohammad Moazzeni Nima Khoramabadi 《Indian journal of microbiology》2013,53(4):391-394
The Helicobacter pylori outer membrane proteins play an important role in pathogenesis; the outer inflammatory protein A (OipA) is one of these proteins which play the main role in the development of inflammation. In this study, purification of recombinant H. pylori OipA was performed by Ni–NTA affinity chromatography. Gastric carcinoma epithelial cells (AGS cell) were treated by different concentrations of recombinant OipA for various lengths of time and cell viability was evaluated by the viability assay. Statistical analysis showed that OipA had toxic effects on AGS cells in a concentration of 500 ng/ml after 24 and 48 h, and this toxic dose was 256 ng/ml after 72 h. OipA had direct toxic effects on gastric epithelial cells and the toxicity was observed to depend on time and dose of H. pylori exposure. Attachment of H. pylori to gastric epithelial cells is a key part in the pathogenesis and enables H. pylori to damage the epithelial cells with OipA. 相似文献