全文获取类型
收费全文 | 135篇 |
免费 | 2篇 |
国内免费 | 2篇 |
出版年
2021年 | 2篇 |
2020年 | 1篇 |
2019年 | 4篇 |
2018年 | 3篇 |
2017年 | 1篇 |
2016年 | 2篇 |
2015年 | 4篇 |
2014年 | 4篇 |
2013年 | 10篇 |
2012年 | 19篇 |
2011年 | 14篇 |
2010年 | 10篇 |
2009年 | 3篇 |
2008年 | 6篇 |
2007年 | 6篇 |
2006年 | 3篇 |
2005年 | 2篇 |
2004年 | 3篇 |
2003年 | 2篇 |
2002年 | 3篇 |
2001年 | 1篇 |
2000年 | 2篇 |
1999年 | 6篇 |
1998年 | 3篇 |
1997年 | 5篇 |
1996年 | 2篇 |
1994年 | 4篇 |
1993年 | 1篇 |
1992年 | 1篇 |
1988年 | 1篇 |
1986年 | 1篇 |
1985年 | 2篇 |
1984年 | 2篇 |
1981年 | 1篇 |
1978年 | 1篇 |
1977年 | 1篇 |
1975年 | 1篇 |
1972年 | 1篇 |
1971年 | 1篇 |
排序方式: 共有139条查询结果,搜索用时 125 毫秒
91.
Commercial enzymes, creatininase (CA) from Pseudomonas sp, creatinase (CI) from Pseudomonas sp, sarcosine oxidase (SO) from Bacillus sp were co-immobilized onto iron oxide nanoparticles/chitosan-graft-polyaniline (Fe(3)O(4)-NPs/CHIT-g-PANI) composite film electrodeposited on surface of Pt electrode through glutaraldehyde coupling. Transmission electron microscopy (TEM) was used for characterization of Fe(3)O(4)-NPs. A creatinine biosensor was fabricated using Enzymes/Fe(3)O(4)-NPs/CHIT-g-PANI/Pt electrode as working electrode, Ag/AgCl as reference electrode and Pt wire as auxiliary electrode. The enzyme electrode was characterized by cyclic voltammetry (CV), scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopic and electrochemical impedance spectroscopy (EIS). The biosensor exhibited an optimum response within 2s at pH 7.5 and 30 °C, when polarized at 0.4V vs Ag/AgCl. The electrocatalytic response showed a linear dependence on creatinine concentration ranging from 1 to 800 μM. The sensitivity of the biosensor was 3.9 μA μM(-1) cm(-2), with a detection limit of 1 μM (S/N=3). Apparent Michaelis-Menton (K(m)) value for creatinine was 0.17 mM. The biosensor showed only 10% loss in its initial response after 120 uses over 200 days, when stored at 4 °C. The biosensor measured creatinine in the serum of apparently healthy persons which correlated well with a standard colorimetric method (r=0.99). 相似文献
92.
Narang J Chauhan N Jain P Pundir CS 《International journal of biological macromolecules》2012,50(3):672-678
A new silver nanoparticles (AgNPs)/carboxylated multiwalled carbon nanotubes (c-MWCNT)/polyaniline (PANI) film has been synthesized on Au electrode using electrochemical techniques. The enzyme glutathione oxidase (GSHOx) (EC 1.8.3.3) was immobilized covalently on the surface of AgNPs/c-MWCNT/PANI/Au electrode to construct the glutathione biosensor. The modified electrode was characterized by scanning electron microscopy (SEM), cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and Fourier transform infrared (FTIR) spectrophotometry. The biosensor showed optimum response within 4s at +0.4V vs. Ag/AgCl, pH 6.0 and 35 °C, with a linear working range of 0.3-3500 μM and a detection limit of 0.3 μM. The glutathione biosensor was employed for measurement of glutathione content in hemolysated erythrocyte (RBC). The sensor was evaluated with 97.77% and 99.16% recovery of added glutathione in hemolysated RBC and 2.4% and 6.3% within and between batch coefficients of variation (CVs) respectively. The enzyme electrode lost 50% of its initial activity after 300 uses over a period of 3 months, when stored at 4 °C. The biosensor has the advantages over earlier biosensors in terms of greater stability, lower response time and no interference by a number of RBC hemolysate substances. 相似文献
93.
94.
Tyrosine sulfation is a ubiquitous posttranslational modification that regulates extracellular protein-protein interactions, intracellular protein transportation modulation, and protein proteolytic process. However, identifying tyrosine sulfation sites remains a challenge due to the lability of sulfation sequences. In this study, we developed a method called PredSulSite that incorporates protein secondary structure, physicochemical properties of amino acids, and residue sequence order information based on support vector machine to predict sulfotyrosine sites. Three types of encoding algorithms-secondary structure, grouped weight, and autocorrelation function-were applied to mine features from tyrosine sulfation proteins. The prediction model with multiple features achieved an accuracy of 92.89% in 10-fold cross-validation. Feature analysis showed that the coil structure, acidic amino acids, and residue interactions around the tyrosine sulfation sites all contributed to the sulfation site determination. The detailed feature analysis in this work can help us to understand the sulfation mechanism and provide guidance for the related experimental validation. PredSulSite is available as a community resource at http://www.bioinfo.ncu.edu.cn/inquiries_PredSulSite.aspx. 相似文献
95.
Metabotrophic glutamate receptors (mGluRs) modulate cellular activities involved in the processes of differentiation and degeneration.
In this study, we have analysed the expression pattern of group-I metabotropic glutamate receptor (mGlu-5) in cerebral cortex,
corpus striatum, brainstem and hippocampus of streptozotocin induced and insulin treated diabetic rats (D+I) as a function
of age. Also, the functional role of glutamate receptors in intra cellular calcium release from the pancreatic islets was
studied in vitro. The gene expression studies showed that mGlu-5 mRNA in the cerebral cortex increased siginficantly in 7 weeks old diabetic
rats whereas decreased expression was observed in brainstem, corpus striatum and hippocampus when compared to control. 90
weeks old diabetic rats showed decreased expression in cerebral cortex, corpus striatum and hippocampus whereas in brainstem
the expression increased significantly compared to their respective controls. In 7 weeks old D+I group, mGlu-5 mRNA expression
was significantly decreased in cerebral cortex and corpus striatum whereas the expression increased significantly in brainstem
and hippocampus. 90 weeks old D+I group showed an increased expression in cerebral cortex, while it was decreased significantly
in corpus striatum, brainstem and hippocampus compared to their respective controls. In vitro studies showed that glutamate at lower concentration (10-7 M) stimulated calcium release from the pancreatic islets. Our results suggest that mGlu-5 receptors have differential expression
in brain regions of diabetes and D+I groups as a function of age. This will have clinical significance in management of degeneration
in brain function and memory enhancement through glutamate receptors. Also, the regulatory role of glutamate receptors in
calcium release has immense therapeutic application in insulin secretion and function. 相似文献
96.
Background
Cancer of the oral tongue is the second most common cancer among males in various parts of India. Despite advances in diagnosis and treatment the failure rates in cancer of the oral tongue are high and survival poor. Majority of these failures occur in untreated neck. 相似文献97.
A method for co-immobilizing lipase from porcine pancreas, glycerol kinase (GK) from Cellulomonas spp., glycerol-3-phosphate oxidase (GPO) from Aerococcus viridans and peroxidase from horseradish onto zirconia-coated alkylamine glass beads through glutaraldehyde coupling has been described. The co-immobilized enzymes retained 71.4% of initial specific activity with a conjugation yield of 43.6 mg/g support. The optimum pH and Km for triolein increased, while Vmax was decreased slightly, but incubation temperature for maximum activity remained unaltered after co-immobilization. The co-immobilized enzymes showed increased thermal and storage stabilities in cold, compared to their native form. Among the various metal salts tested, only CuSO4 caused inhibition of both free and co-immobilized enzymes. The co-immobilized enzymes showed better suitability over mixture of individually immobilized enzymes in determination of serum triglyceride. 相似文献
98.
99.
Tonic GABAergic inhibition of taste-responsive neurons in the nucleus of the solitary tract 总被引:4,自引:1,他引:3
The effects of gamma-aminobutyric acid (GABA) and the GABAA receptor
antagonist bicuculline methiodide (BICM) on the activity of taste-
responsive neurons in the nucleus of the solitary tract (NST) were examined
electrophysiologically in urethane-anesthetized hamsters. Single neurons in
the NST were recorded extracellularly and drugs (21 nl) were microinjected
into the vicinity of the cell via a multibarrel pipette. The response of
each cell was recorded to lingual stimulation with 0.032 M NaCl, 0.032 M
sucrose, 0.0032 M citric acid and 0.032 M quinine hydrochloride (QHCl).
Forty-six neurons were tested for the effects of GABA; the activity of 29
cells (63%) was inhibited by 5 mM GABA. Whether activity was elicited in
these cells by repetitive anodal current stimulation (25 microA, 0.5 s, 0.1
Hz) of the tongue (n = 13 cells) or the cells were spontaneously active (n
= 13 cells), GABA produced a dose-dependent (1, 2 and 5 mM) decrement in
activity. Forty- seven NST neurons were tested for the effects of BICM on
their responses to chemical stimulation of the tongue; the responses of 28
cells (60%) were enhanced by 10 mM BICM. The gustatory responses of 26 of
these cells were tested with three concentrations (0.2, 2 and 10 mM) of
BICM, which produced a dose-dependent increase in both spontaneous activity
and taste-evoked responses. Nine of these neurons were sucrose- best, seven
were NaCl-best, eight were acid-best and two responded best to QHCl. The
responses to all four tastants were enhanced, with no difference among
neuron types. For 18 cells that were tested with two or more gustatory
stimuli, BICM increased their breadth of responsiveness to their two most
effective stimuli. These data show that approximately 60% of the
taste-responsive neurons in the rostral NST are inhibited by GABA and/or
subject to a tonic inhibitory influence, which is mediated by GABAA
receptors. The modulation of these cells by GABA provides a mechanism by
which the breadth of tuning of the cell can be sharpened. Modulation of
gustatory activity following a number of physiological changes could be
mediated by such a GABAergic circuit.
相似文献
100.
Molecular evolution of the Sex-Ratio inversion complex in Drosophila pseudoobscura: analysis of the Esterase-5 gene region 总被引:2,自引:0,他引:2
The Sex-Ratio chromosome in Drosophila pseudoobscura is subject to meiotic
drive. It is associated with a series of three nonoverlapping paracentric
inversions on the right arm of the X chromosome. The esterase-5 gene region
has been localized to section 23 within the subbasal inversion of the
Sex-Ratio inversion complex, making esterase- 5 a convenient locus for
molecular evolutionary analyses of the Sex- Ratio inversion complex and the
associated drive system. A 504-bp fragment of noncoding, intergenic DNA
from the esterase-5 gene region was amplified and sequenced from 14
Sex-Ratio and 14 Standard X chromosomes of D. pseudoobscura, and from 9 X
chromosomes of its two sibling species, Drosophila persimilis and
Drosophila miranda. There is extensive sequence differentiation between the
Sex-Ratio and Standard chromosomal types. The common Standard chromosome is
highly polymorphic, while, as expected from either the neutral mutation
theory or the selective sweep hypothesis, the rarer Sex-Ratio chromosome
has much less within-chromosome nucleotide polymorphism. We estimate that
the Standard and Sex-Ratio chromosomes in D. pseudoobscura diverged between
700,000 and 1.3 Mya, or at least 2 million generations ago. The clustering
of D. pseudoobscura Sex-Ratio chromosomes in a neighbor- joining phylogeny
indicates a fairly old, monophyletic origin in this species. It appears
from these data that Sex-Ratio genes were present prior to the divergence
of D. pseudoobscura and D. persimilis and that both the Standard and
Sex-Ratio chromosomes of D. persimilis were derived from the Standard
chromosome of D. pseudoobscura after the inversion events that isolated the
D. pseudoobscura Sex-Ratio chromosome.
相似文献