全文获取类型
收费全文 | 188篇 |
免费 | 37篇 |
国内免费 | 2篇 |
出版年
2022年 | 2篇 |
2020年 | 3篇 |
2016年 | 3篇 |
2015年 | 11篇 |
2014年 | 8篇 |
2013年 | 4篇 |
2012年 | 13篇 |
2011年 | 12篇 |
2010年 | 6篇 |
2009年 | 6篇 |
2008年 | 10篇 |
2007年 | 8篇 |
2006年 | 8篇 |
2005年 | 8篇 |
2004年 | 9篇 |
2003年 | 7篇 |
2002年 | 7篇 |
2001年 | 8篇 |
2000年 | 5篇 |
1999年 | 6篇 |
1998年 | 6篇 |
1997年 | 2篇 |
1996年 | 9篇 |
1995年 | 2篇 |
1994年 | 5篇 |
1993年 | 5篇 |
1992年 | 4篇 |
1991年 | 2篇 |
1990年 | 1篇 |
1989年 | 4篇 |
1988年 | 2篇 |
1987年 | 1篇 |
1986年 | 2篇 |
1985年 | 3篇 |
1984年 | 1篇 |
1983年 | 2篇 |
1982年 | 3篇 |
1981年 | 2篇 |
1980年 | 2篇 |
1978年 | 2篇 |
1977年 | 3篇 |
1976年 | 1篇 |
1975年 | 3篇 |
1974年 | 3篇 |
1972年 | 4篇 |
1971年 | 1篇 |
1970年 | 1篇 |
1969年 | 1篇 |
1967年 | 2篇 |
1966年 | 2篇 |
排序方式: 共有227条查询结果,搜索用时 15 毫秒
41.
42.
43.
Modified procedures for separating and determining adenine nucleotides are described. Separation was achieved by one-dimensional thin-layer chromatography on polyethyleneimine-cellulose plates in 1.4
LiCl after prewashing the spotted plate in deionized water. The fluorometric procedure for determining adenine and adenine derivatives using glyoxal dihydrate trimer was modified to reduce the heat step from 3 hr to 25 min without loss of sensitivity or stability. These modified procedures were used to determine the adenine nucleotide levels in rat liver. 相似文献
44.
Triplett JW O'Riley R Tekulve K Norvell SM Pavalko FM 《Molecular & cellular biomechanics : MCB》2007,4(1):13-25
Maintenance of optimal bone physiology requires the coordinated activity of osteoclasts that resorb old bone and osteoblasts that deposit new bone. Mechanical loading of bone and the resulting movement of interstitial fluid within the spaces surrounding bone cells is thought to play a key role is maintaining optimal bone mass. One way in which fluid movement may promote bone formation is by enhancing osteoblast survival. We have shown previously that application of fluid flow to osteoblasts in vitro confers a protective effect by inhibiting osteoblast apoptosis (Pavalko et al., 2003, J. Cell Physiol., 194: 194-205). To investigate the cellular mechanisms that regulate the response of osteoblasts to fluid shear stress, we have examined the possible interaction between fluid flow and growth factors in MC3T3-E1 osteoblast-like cells. We found that insulin-like growth factor-I (IGF-I) was significantly more effective at preventing TNF-alpha-induced apoptosis when cells were first subjected to mechanical loading by exposure to either unidirectional or oscillatory fluid flow compared to cells that were maintained in static culture. Additionally, downstream signaling in response to treatment with IGF-I, including ERK and Akt activation, was enhanced in cells that were subjected to fluid flow, compared to cells maintained in static culture. Furthermore, we found that PKC activity is essential for fluid shear stress sensitization of IGF-IR, since a specific inhibitor of PCKzeta function blocked the flow-enhanced IGF-I-activated Akt and ERK phosphorylation. Together, our results suggest that fluid shear stress may regulate IGF-I signaling in osteoblasts in a PKC-zeta-dependent manner. 相似文献
45.
Kirby TJ Triplett NT Haines TL Skinner JW Fairbrother KR McBride JM 《Amino acids》2012,42(5):1987-1996
The purpose of this study was to determine the effect of leucine supplementation on indices of muscle damage following eccentric-based
resistance exercise. In vitro, the amino acid leucine has been shown to reduce proteolysis and stimulate protein synthesis.
Twenty-seven untrained males (height 178.6 ± 5.5 cm; body mass 77.7 ± 13.5 kg; age 21.3 ± 1.6 years) were randomly divided
into three groups; leucine (L) (n = 10), placebo (P) (n = 9) and control (C) (n = 8). The two experimental groups (L and P) performed 100 depth jumps from 60 cm and six sets of ten repetitions of eccentric-only
leg presses. Either leucine (250 mg/kg bm) or placebo was ingested 30 min before, during and immediately post-exercise and
the morning of each recovery day following exercise. Muscle function was determined by peak force during an isometric squat
and by jump height during a static jump at pre-exercise (PRE) and 24, 48, 72, and 96 h post-exercise (24, 48, 72, 96 h). Additionally,
at these time points each group’s serum levels of creatine kinase (CK) and myoglobin (Mb) along with perceived feelings of
muscle soreness were determined. None of the C group dependent variables was altered by the recurring testing procedures.
Peak force was significantly decreased across all time points for both experimental groups. The L group experienced an attenuated
drop in mean peak force across all post-exercise time points compared to the P group. Jump height significantly decreased
from PRE for both the L and P group at 24 h and 48 h. CK and Mb was significantly elevated from PRE for both experimental
groups at 24 h. Muscle soreness increased across all time points for the both the L and P group, and the L group experienced
a significantly higher increase in mean muscle soreness post-exercise. Following exercise-induced muscle damage, high-dose
leucine supplementation may help maintain force output during isometric contractions, however, not force output required for
complex physical tasks thereby possibly limiting its ergogenic effectiveness. 相似文献
46.
MacDonald MJ Chaplen FW Triplett CK Gong Q Drought H 《Archives of biochemistry and biophysics》2006,447(2):118-126
Glyceraldehyde (GA) has been used to study insulin secretion for decades and it is widely assumed that beta-cell metabolism of GA after its phosphorylation by triokinase is similar to metabolism of glucose; that is metabolism through distal glycolysis and oxidation in mitochondria. New data supported by existing information indicate that this is true for only a small amount of GA's metabolism and also suggest why GA is toxic. GA is metabolized at 10-20% the rate of glucose in pancreatic islets, even though GA is a more potent insulin secretagogue. GA also inhibits glucose metabolism to CO2 out of proportion to its ability to replace glucose as a fuel. This study is the first to measure methylglyoxal (MG) in beta-cells and shows that GA causes large increases in MG in INS-1 cells and d-lactate in islets but MG does not mediate GA-induced insulin release. GA severely lowers NAD(P) and increases NAD(P)H in islets. High NADH combined with GA's metabolism to CO2 may initially hyperstimulate insulin release, but a low cytosolic NAD/NADH ratio will block glycolysis at glyceraldehyde phosphate (GAP) dehydrogenase and divert GAP toward MG and D-lactate formation. Accumulation of D-lactate and 1-phosphoglycerate may explain why GA makes the beta-cell acidic. Reduction of both GA and MG by abundant beta-cell aldehyde reductases will lower the cytosolic NADPH/NADP ratio, which is normally high. 相似文献
47.
48.
The presence of human-pathogenic, enteric bacteria on the surface and in the interior of raw produce is a significant health concern. Several aspects of the biology of the interaction between these bacteria and alfalfa (Medicago sativa) seedlings are addressed here. A collection of enteric bacteria associated with alfalfa sprout contaminations, along with Escherichia coli K-12, Salmonella enterica serotype Typhimurium strain ATCC 14028, and an endophyte of maize, Klebsiella pneumoniae 342, were labeled with green fluorescent protein, and their abilities to colonize the rhizosphere and the interior of the plant were compared. These strains differed widely in their endophytic colonization abilities, with K. pneumoniae 342 and E. coli K-12 being the best and worst colonizers, respectively. The abilities of the pathogens were between those of K. pneumoniae 342 and E. coli K-12. All Salmonella bacteria colonized the interiors of the seedlings in high numbers with an inoculum of 10(2) CFU, although infection characteristics were different for each strain. For most strains, a strong correlation between endophytic colonization and rhizosphere colonization was observed. These results show significant strain specificity for plant entry by these strains. Significant colonization of lateral root cracks was observed, suggesting that this may be the site of entry into the plant for these bacteria. At low inoculum levels, a symbiosis mutant of Medicago truncatula, dmi1, was colonized in higher numbers on the rhizosphere and in the interior by a Salmonella endophyte than was the wild-type host. Endophytic entry of M. truncatula appears to occur by a mechanism independent of the symbiotic infections by Sinorhizobium meliloti or mycorrhizal fungi. 相似文献
49.
50.
Phosphoglucomutase (EC 2.7.5.1, PGM) was purified to homogeneity from maize (Zea mays L.) leaves. The enzyme had specific activity 11. 7 U/mg protein and molecular mass (determined by gel-chromatography) of 133 +/- 4 kD. The molecular mass of PGM subunits determined by SDS-electrophoresis was 66 +/- 3 kD. The enzyme had Km for glucose-1-phosphate and glucose-1,6-diphosphate of 20.0 +/- 0.9 and 16.0 +/- 0.8 &mgr;M, respectively. Concentrations of glucose-1-phosphate and glucose-1,6-diphosphate above 3 and 0.4 mM, respectively, cause substrate inhibition. The enzyme activity was maximal at pH 8.0 and temperature 35 degreesC. Magnesium ions activate the enzyme and manganese ions inhibit it. 3-Phosphoglycerate is an uncompetitive inhibitor of the enzyme (Ki = 1.22 +/- 0.05 mM). Fructose-6-phosphate, 6-phosphogluconate, and ADP activate PGM, whereas ATP, UTP, and AMP inhibit the enzyme. Citrate was also a potent inhibitor, inhibitory effects of isocitrate and cis-aconitate being less pronounced. 相似文献