全文获取类型
收费全文 | 302篇 |
免费 | 31篇 |
出版年
2023年 | 3篇 |
2022年 | 7篇 |
2021年 | 11篇 |
2020年 | 4篇 |
2019年 | 11篇 |
2018年 | 10篇 |
2017年 | 10篇 |
2016年 | 18篇 |
2015年 | 18篇 |
2014年 | 26篇 |
2013年 | 28篇 |
2012年 | 24篇 |
2011年 | 15篇 |
2010年 | 12篇 |
2009年 | 15篇 |
2008年 | 12篇 |
2007年 | 14篇 |
2006年 | 21篇 |
2005年 | 15篇 |
2004年 | 5篇 |
2003年 | 10篇 |
2002年 | 10篇 |
2001年 | 2篇 |
2000年 | 3篇 |
1999年 | 2篇 |
1998年 | 3篇 |
1997年 | 2篇 |
1996年 | 3篇 |
1995年 | 2篇 |
1994年 | 1篇 |
1993年 | 1篇 |
1991年 | 1篇 |
1990年 | 2篇 |
1989年 | 1篇 |
1986年 | 1篇 |
1981年 | 1篇 |
1980年 | 1篇 |
1978年 | 2篇 |
1976年 | 1篇 |
1975年 | 1篇 |
1971年 | 3篇 |
1968年 | 1篇 |
排序方式: 共有333条查询结果,搜索用时 15 毫秒
1.
Svenja Viete Walter Heiligenberg 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》1991,169(1):15-23
Summary In its Jamming Avoidance Response (JAR), the gymnotiform electric fish Eigenmannia shifts its electric organ discharge (EOD) frequency away from similar interfering frequencies. Continual behavioral measurements were carried out in 164 juvenile fish until a correct JAR emerged. Sixty-four of these fish were raised in complete isolation, the remainder in a community of their siblings. A correct JAR emerged in fish of 1.2–1.6 cm in body length, corresponding to a developmental age of 24–32 days. In 6 of 164 fish, the emergence of a correct JAR followed an interim appearance of an incorrect JAR, which involved frequency shifts in the direction opposite to those of a correct JAR. The fish raised in isolation developed the same forms of behavior and showed the same sequence in their appearance as did socially raised fish. This indicates that the JAR and its developmental schedule are innate. The appearance of an incorrect JAR suggests initial errors or incompleteness in the wiring of central nervous connections. A correct JAR ultimately emerged even if a stimulus regimen was offered that rewarded frequency shifts in the direction opposite to those of a correct JAR. This indicates that the development of the JAR is immune to experimental alterations of sensory experience.Abbreviations
Df
frequency difference between a jamming stimulus and fish's EOD
-
ELL
electrosensory lateral line lobe
-
EO
electric organ
-
EOD
electric organ discharge
-
JAR
Jamming Avoidance Response
-
nE
nucleus electrosensorius
-
nE
subnucleus of nE, causing drop of EOD frequency
-
nE
subnucleus of nE, causing rise of EOD frequency
-
Pn
pacemaker nucleus
-
PPn
prepacemaker nucleus 相似文献
2.
Abstract: Nuclear magnetic resonance (NMR) was used to study the metabolic pathways involved in the conversion of glucose to glutamate, γ-aminobutyrate (GABA), glutamine, and aspartate. d -[1-13C]Glucose was administered to rats intraperitoneally, and 6, 15, 30, or 45 min later the rats were killed and extracts from the forebrain were prepared for 13C-NMR analysis and amino acid analysis. The absolute amount of 13C present within each carbon-atom pool was determined for C-2, C-3, and C-4 of glutamate, glutamine, and GABA, for C-2 and C-3 of aspartate, and for C-3 of lactate. The natural abundance 13C present in extracts from control rats was also determined for each of these compounds and for N-acetylaspartate and taurine. The pattern of labeling within glutamate and GABA indicates that these amino acids were synthesized primarily within compartments in which glucose was metabolized to pyruvate, followed by decarboxylation to acetyl-CoA for entry into the tricarboxylic acid cycle. In contrast, the labeling pattern for glutamine and aspartate indicates that appreciable amounts of these amino acids were synthesized within a compartment in which glucose was metabolized to pyruvate, followed by carboxylation to oxaloacetate. These results are consistent with the concept that pyruvate carboxylase and glutamine synthetase are glia-specific enzymes, and that this partially accounts for the unusual metabolic compartmentation in CNS tissues. The results of our study also support the concept that there are several pools of glutamate, with different metabolic turnover rates. Our results also are consistent with the concept that glutamine and/or a tricarboxylic acid cycle intermediate is supplied by astrocytes to neurons for replenishing the neurotransmitter pool of GABA. However, a similar role for astrocytes in replenishing the transmitter pool of glutamate was not substantiated, possibly due to difficulties in quantitating satellite peaks arising from 13C-13C coupling. 相似文献
3.
Astrocytes are the primary site of glutamate conversion to glutamine in the brain. We examined the effects of treatment with either dibutyryl cyclic AMP and/or the synthetic glucocorticoid dexamethasone on glutamine synthetase enzyme activity and steady-state mRNA levels in cultured neonatal rat astrocytes. Treatment of cultures with dibutyryl cyclic AMP alone (0.25 mM–1.0 mM) increased glutamine synthetase activity and steady state mRNA levels in a dose-dependent manner. Similarly, treatment with dexamethasone alone (10–7–10–5 M) increased glutamine synthetase mRNA levels and enzyme activity. When astrocytes were treated with both effectors, additive increases in glutamine synthetase activity and mRNA were obtained. However, the additive effects were observed only when the effect of dibutyryl cyclic AMP alone was not maximal. These findings suggest that the actions of these effectors are mediated at the level of mRNA accumulation. The induction of glutamine synthetase mRNA by dibutyryl cyclic AMP was dependent on protein synthesis while the dexamethasone effect was not. Glucocorticoids and cyclic AMP are known to exert their effects on gene expression by different molecular mechanisms. Possible crosstalk between these effector pathways may occur in regulation of astrocyte glutamine synthetase expression.Abbreviations used GS
glutamine synthetase
- dbcAMP
dibutyryl cyclic AMP
- MEM
minimal essential medium
- cyx
cycloheximide
- GRE
glucocorticoid response element
- CRE
cyclic AMP response element 相似文献
4.
Reciprocal regulation of glucose and glutamine utilization by cultured human diploid fibroblasts 总被引:10,自引:0,他引:10
H R Zielke P T Ozand J T Tildon D A Sevdalian M Cornblath 《Journal of cellular physiology》1978,95(1):41-48
Human diploid fibroblasts utilize both glucose and glutamine as energy sources. The utilization of glutamine by fibroblasts is regulated by glucose, and vice versa. This conclusion is supported by the following observations: (1) essentially identical growth rates were observed in Eagle's minimum essential medium (MEM)3 in which the glucose concentration was either 5.5 mM or was maintained between 25 and 40 micrometer, (2) the total glutamine utilization by fibroblasts increase at least 30% in medium with 25 micrometer to 70 micrometer glucose compared to medium with 5.5 mM glucose, while the rate of glutamine-1 or 5-14C oxidation to CO2 increased 5-fold as the glucose concentration was decreased to zero, (3) 2 mM glutamine inhibited glucose-6-14C oxidation by 88% and stimulated glucose-1-14C by 77% in log phase cells and (4) glutamine oxidation in normal medium contributed approximately 30% of the energy requirement of human diploid fibroblasts. 相似文献
5.
A permanent human lymphoblast culture was synchronized with repetitive thymidine blocks, and the changes in the levels of activity of four X-chromosome-linked enzymes were followed during the cell cycle. The four enzymes studied were phosphoglycerate kinase (PGK), α-galactosidase (α-Gal), hypoxanthine-guanine phosphoribosyltransferase (HGPRT), and glucose-6-phosphate dehydrogenase (G6PD). The levels of PGK and α-Gal activities increased simultaneously in G1 and in S, while HGPRT and G6PD increased close together in middle and late S. Therefore, different control mechanisms may be involved in the increases of the activities of these two sets of enzymes. 相似文献
6.
Madritsch Silvia Bomers Svenja Posekany Alexandra Burg Agnes Birke Rebekka Emerstorfer Florian Turetschek Reinhard Otte Sandra Eigner Herbert Sehr Eva M. 《Plant molecular biology》2020,104(4-5):379-380
Plant Molecular Biology - In the above mentioned publication, part of Fig. 6B was distorted (extra diagonal lines appeared). The original article has been corrected and the proper version... 相似文献
7.
8.
9.
Leonard Schmiester Yannik Schlte Frank T. Bergmann Tacio Camba Erika Dudkin Janine Egert Fabian Frhlich Lara Fuhrmann Adrian L. Hauber Svenja Kemmer Polina Lakrisenko Carolin Loos Simon Merkt Wolfgang Müller Dilan Pathirana Elba Raimúndez Lukas Refisch Marcus Rosenblatt Paul L. Stapor Philipp Stdter Dantong Wang Franz-Georg Wieland Julio R. Banga Jens Timmer Alejandro F. Villaverde Sven Sahle Clemens Kreutz Jan Hasenauer Daniel Weindl 《PLoS computational biology》2021,17(1)
Reproducibility and reusability of the results of data-based modeling studies are essential. Yet, there has been—so far—no broadly supported format for the specification of parameter estimation problems in systems biology. Here, we introduce PEtab, a format which facilitates the specification of parameter estimation problems using Systems Biology Markup Language (SBML) models and a set of tab-separated value files describing the observation model and experimental data as well as parameters to be estimated. We already implemented PEtab support into eight well-established model simulation and parameter estimation toolboxes with hundreds of users in total. We provide a Python library for validation and modification of a PEtab problem and currently 20 example parameter estimation problems based on recent studies. 相似文献