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991.
In our previous study using a fluorescently labeled cohesin biomarker, we detected and identified a putative cellulosomal
mannanase belonging to the glycosyl hydrolase family 26 from Clostridium cellulovorans in xylan-containing cultures. In this study, a mannanase gene, manB from C. cellulovorans, was expressed in Escherichia coli. The optimal pH of a purified enzyme was around pH 7.0 and the optimal temperature was 40°C. The purified mannanase B (ManB)
showed high hydrolytic activity toward galactomannan. An assembly of ManB with mini-CbpA, which contains a carbohydrate-binding
module that provides proximity to insoluble substrates, increased the activity toward galactomannan [locust bean gum (LBG)
and guar gum] 1.7- and 2.0-fold over those without mini-CbpA. We tested the synergistic effects on galactomannan (LBG and
guar gum) degradation using cellulosomal mannanase ManB with cellulosomal endoglucanase E, which was predicted to have mannanase
activity in C. cellulovorans as a cellulolytic complex. When assembled with the mini-CbpA, the mixture of endoglucanase E (EngE) and ManB at a molar ratio
of 1:2 showed the highest synergistic effect (2.4-fold) on LBG. The mixture at a ratio of 1:3 showed the highest synergistic
effect (2.8-fold) on guar gum. These synergistic actions indicated that ManB assembled with mini-CbpA hydrolyzed insoluble
galactomannan, which in turn promoted soluble galactomannan degradation by EngE. 相似文献
992.
Choi JH Yoo KY Lee CH Yi SS Yoo DY Seong JK Yoon YS Hwang IK Won MH 《Cellular and molecular neurobiology》2011,31(2):285-292
N-methyl-d-aspartate receptor (NR) is involved in activity-dependent synaptic plasticity, such as associative long-term potentiation,
and in related central functions, such as learning and memory. In this study, we observed effects of treadmill exercise on
NR1 and doublecortin (DCX, a marker for neuroblast differentiation) in the subgranular zone of the dentate gyrus (DG). At
6 weeks of age, rats were put on a treadmill with or without running for 1 h/day for 5 consecutive days at 22 m/min for 5 weeks.
Exercise increased NR1 immunoreactivity and protein level in the hippocampus. To identify the correlations between NR and
neuroblasts, we intraperitoneally administered a NR antagonist, MK-801, to the exercised rats. MK-801 treatment reduced NR1
protein level in the hippocampus of the exercised rats. In addition, in the MK-801-treated group, the number of DCX cells
was significantly decreased in the subgranular zone of the DG. These results suggest that NR may be one of the important factors
that modulate neuroblast differentiation during exercise in rats. 相似文献
993.
Subramanya Srikantan Kotb Abdelmohsen Eun Kyung Lee Kumiko Tominaga Sarah S. Subaran Yuki Kuwano Ritu Kulshrestha Rohit Panchakshari Hyeon Ho Kim Xiaoling Yang Jennifer L. Martindale Bernard S. Marasa Mihee M. Kim Robert P. Wersto Fred E. Indig Dipanjan Chowdhury Myriam Gorospe 《Molecular and cellular biology》2011,31(18):3790-3801
994.
Tominaga K Srikantan S Lee EK Subaran SS Martindale JL Abdelmohsen K Gorospe M 《Molecular and cellular biology》2011,31(20):4219-4231
995.
The macrolide antibiotics are biosynthesized by initial assembly of a macrolactone ring, followed by a series of post-polyketide
(PKS) modifications. In general, the additional hydroxyl or epoxy groups are installed by cytochrome P450 enzymes, improving
the bioactivity profile through structural diversification of natural products. The biosynthetic gene cluster for the 16-membered
macrolide antibiotic dihydrochalcomycin (DHC) has been cloned from Streptomyces sp. KCTC 0041BP. Three cytochrome P450 genes are found in the DHC biosynthetic gene (ger) cluster. Two P450 enzymes were characterized from this cluster. Disruption of gerPI accumulated predominantly 12,13-de-epoxydihydrochalcomycin while disruption of gerPII accumulated 8-dehydroxy-12,13-de-epoxydihydrochalcomycin; DHC production was abolished in both cases. The results suggest
that GerPII P450 catalyzes hydroxylation at the C8 position followed by an epoxidation reaction catalyzed by GerPI P450 at the C12–C13 position. 相似文献
996.
The Shelterin complex associates with telomeres and plays an essential role in telomere protection and telomerase regulation. In its most abundant form, the complex is composed of six core components: TRF1, TRF2, POT1, TIN2, TPP1 and RAP1. Of these subunits, three can interact directly with either single-stranded (POT1) or double-stranded (TRF1, TRF2) telomeric DNA. In this report, we have developed assays to measure the DNA binding activity of Shelterin complexes in human cell extracts. With these assays, we have characterized the composition and DNA binding specificity of two Shelterin complexes: a 6-member complex that contains all six core components and a second complex that lacks TRF1. Our results show that both of these complexes bind with high affinity (K(D) = 1.3-1.5 × 10(-9) M) and selectively to ds/ss-DNA junctions that carry both a binding site for POT1 (ss-TTAGGGTTAG) and a binding site for the SANT/Myb domain of TRF1 or TRF2 (ds-TTAGGGTTA). This DNA binding specificity suggests the preferential recruitment of these complexes to areas of the telomere where ss- and ds-DNA are in close proximity, such as the 3'-telomeric overhang, telomeric DNA bubbles and the D-loop at the base of T-loops. 相似文献
997.
Kim DH Jung YJ Lee JE Lee AS Kang KP Lee S Park SK Han MK Lee SY Ramkumar KM Sung MJ Kim W 《American journal of physiology. Renal physiology》2011,301(2):F427-F435
Nephrotoxicity is one of the important dose-limiting factors during cisplatin treatment. There is a growing body of evidence that activation of p53 has a critical role in cisplatin-induced renal apoptotic injury. The nicotinamide adenine dinucleotide-dependent protein deacetylase SIRT1 decreases apoptosis through deacetylating of p53, and resveratrol is known as an activator of SIRT1. To study the role of SIRT1 in cisplatin-induced renal injury through interaction with p53, mouse proximal tubular cells (MPT) were treated with cisplatin and examined the expression level of SIRT1, acetylation of p53, PUMA-α, Bax, the cytosolic/mitochondrial cytochrome c ratio, and active caspase-3. The expression of SIRT1 was decreased by cisplatin. Resveratrol, a SIRT1 activator, ameliorated cisplatin-induced acetylation of p53, apoptosis, and cytotoxicity in MPT cells. In addition, resveratrol remarkably blocked cisplatin-induced decrease of Bcl-xL in MPT cells. Further specific SIRT1 inhibition with EX 527 or small interference RNA specific to SIRT1 reversed the effect of resveratrol on cisplatin-induced toxicity. Inhibition of p53 by pifithrin-α reversed the effect of EX527 in protein expression of PUMA-α, Bcl-xL, and caspase-3 and cytotoxicity in MPT cells. SIRT1 protein expression after cisplatin treatment was significantly decreased in the kidney. SIRT1 activation by resveratrol decreased cisplatin-induced apoptosis while improving the glomerular filtration rate. Taken together, our findings suggest that the modulation of p53 by SIRT1 could be a possible target to attenuate cisplatin-induced kidney injury. 相似文献
998.
Hwang IK Yi SS Yoo KY Park OK Yan B Song W Won MH Yoon YS Seong JK 《Neurochemical research》2011,36(8):1526-1532
In the present study, we investigated the effects of treadmill exercise in early and chronic diabetic stages on parvalbumin
(PV) immunoreactivity in the subgranular zone of the dentate gyrus of Zucker diabetic fatty (ZDF) and its lean control rats
(ZLC). To investigate the effects, ZLC and ZDF rats at 6 or 23 weeks of age were put on a treadmill with or without running
for 1 h/day/5 consecutive days at 16–22 m/min for 5 weeks or 12–16 m/min for 7 weeks, respectively. Physical exercise in pre-diabetic
rats prevented onset of diabetes, while exercise in rats at chronic diabetic stage significantly reduced blood glucose levels.
In addition, physical exercise in the pre-diabetic rats significantly increased PV immunoreactive fibers in the strata oriens
and radiatum of the CA1-3 region and in the polymorphic and molecular layers of the dentate gyrus compared to that in sedentary
controls. However, in rats at chronic stages, PV immunoreactivity was slightly increased in the CA1-3 region as well as in
the dentate gyrus compared to that in the sedentary controls. These results suggest that physical exercise has differential
effects on blood glucose levels and PV immunoreactivity according to diabetic stages. Early exercise improves diabetic phenotype
and PV immunoreactive fibers in the rat hippocampus. 相似文献
999.
Yong Kyung LeeIm Seop Choi Jung Ok BanHwa Jeong Lee Ung Soo LeeSang Bae Han Jae Kyung JungYoung Hee Kim Ki Ho KimKi-Wan Oh Jin Tae Hong 《The Journal of nutritional biochemistry》2011,22(5):476-486
Oxidative stress induced neuronal cell death by accumulation of β-amyloid (Aβ) is a critical pathological mechanism of Alzheimer's disease (AD). Intracerebroventrical infusion of Aβ1-42 (300 pmol/day per mouse) for 14 days induced neuronal cell death and memory impairment, but pre-treatment of 4-O-methylhonokiol (4-O-MH), a novel compound extracted from Magnolia officinalis for 3 weeks (0.2, 0.5 and 1.0 mg/kg) prior to the infusion of Aβ1-42 and during the infusion dose dependently improved Aβ1-42-induced memory impairment and prevented neuronal cell death. Additionally, 4-O-MH reduced Aβ1-42 infusion-induced oxidative damages of protein and lipid but reduced glutathione levels in the cortex and hippocampus. Aβ1-42 infusion-induced activation of astrocytes and p38 mitogenic activated protein (MAP) kinase was also prevented by 4-O-MH in mice brains. In further study using culture cortical neurons, p38 MAP kinase inhibitor abolished the inhibitory effect of 4-O-MH (10 μM) on the Aβ1-42 (5 μM)-induced reactive oxidative species generation and neuronal cell death. These results suggest that 4-O-MH might prevent the development and progression of AD through the reduction of oxidative stress and neuronal cell death via inactivation of p38 MAP kinase pathway. 相似文献
1000.
The naturally occurring yellow dietary diarylheptanoid curcumin (1) was converted by γ-ray to two new γ-lactones, curculactones A (2) and B (3), as well as four known transformates, erythro-1-(3-methoxy-4-hydroxy-phenyl)-propan-1,2-diol (4), threo-1-(3-methoxy-4-hydroxy-phenyl)-propan-1,2-diol (5), vanillic acid (6), and vanillin (7). The structures of the two new γ-lactone derivatives were elucidated on the basis of spectroscopic methods. The steroisomeric phenylpropanoids 4 and 5 exhibited significantly enhanced inhibitory activity against pancreatic lipase when compared to parent curcumin. 相似文献