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1.
一种智能化的Y—型迷宫   总被引:79,自引:1,他引:78  
本文介绍了一种智能化Y-型迷宫的硬件、软件结构。它利用微机控制大鼠(或小鼠)分辨学习实验的全过程,利用红外光电传感器监测动物活动行为,判断准确,计时精确。由于以WINDOWS为工作平台,人机界面友好,操作简便。  相似文献
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寄生蜂寄主选择行为研究进展   总被引:55,自引:2,他引:53       下载免费PDF全文
侯照远  严福顺 《昆虫学报》1997,40(1):94-107
寄生蜂是膜翅目昆虫中的重要类群,在自然界种类多,数量大。据文献报道全世界膜翅目昆虫大约有10万种”’,其中许多种类与农林害虫长期保持一定的制约关系,在害虫防治中占有重要地位。由于大量使用化学农药导致害虫的抗药性增加,利用天敌昆虫来防治害虫越来越显示出其重要性和优越性。但是,直到近20年来,寄生蜂的寄生行为才受到重视,并给予了广泛的、深入的研究”-‘’严格地讲,寄生蜂应该称为拟寄生蜂,它与通常所说的寄生昆虫像虱子、臭虫等有明显不同,主要区别在于:1.寄生仅仅发生在未成熟阶段,而成虫阶段营自由生活;2.寄…  相似文献
4.
A combined transmembrane topology and signal peptide prediction method   总被引:29,自引:0,他引:29  
An inherent problem in transmembrane protein topology prediction and signal peptide prediction is the high similarity between the hydrophobic regions of a transmembrane helix and that of a signal peptide, leading to cross-reaction between the two types of predictions. To improve predictions further, it is therefore important to make a predictor that aims to discriminate between the two classes. In addition, topology information can be gained when successfully predicting a signal peptide leading a transmembrane protein since it dictates that the N terminus of the mature protein must be on the non-cytoplasmic side of the membrane. Here, we present Phobius, a combined transmembrane protein topology and signal peptide predictor. The predictor is based on a hidden Markov model (HMM) that models the different sequence regions of a signal peptide and the different regions of a transmembrane protein in a series of interconnected states. Training was done on a newly assembled and curated dataset. Compared to TMHMM and SignalP, errors coming from cross-prediction between transmembrane segments and signal peptides were reduced substantially by Phobius. False classifications of signal peptides were reduced from 26.1% to 3.9% and false classifications of transmembrane helices were reduced from 19.0% to 7.7%. Phobius was applied to the proteomes of Homo sapiens and Escherichia coli. Here we also noted a drastic reduction of false classifications compared to TMHMM/SignalP, suggesting that Phobius is well suited for whole-genome annotation of signal peptides and transmembrane regions. The method is available at as well as at  相似文献
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O-GalNAc-glycosylation is one of the main types of glycosylation in mammalian cells. No consensus recognition sequence for the O-glycosyltransferases is known, making prediction methods necessary to bridge the gap between the large number of known protein sequences and the small number of proteins experimentally investigated with regard to glycosylation status. From O-GLYCBASE a total of 86 mammalian proteins experimentally investigated for in vivo O-GalNAc sites were extracted. Mammalian protein homolog comparisons showed that a glycosylated serine or threonine is less likely to be precisely conserved than a nonglycosylated one. The Protein Data Bank was analyzed for structural information, and 12 glycosylated structures were obtained. All positive sites were found in coil or turn regions. A method for predicting the location for mucin-type glycosylation sites was trained using a neural network approach. The best overall network used as input amino acid composition, averaged surface accessibility predictions together with substitution matrix profile encoding of the sequence. To improve prediction on isolated (single) sites, networks were trained on isolated sites only. The final method combines predictions from the best overall network and the best isolated site network; this prediction method correctly predicted 76% of the glycosylated residues and 93% of the nonglycosylated residues. NetOGlyc 3.1 can predict sites for completely new proteins without losing its performance. The fact that the sites could be predicted from averaged properties together with the fact that glycosylation sites are not precisely conserved indicates that mucin-type glycosylation in most cases is a bulk property and not a very site-specific one. NetOGlyc 3.1 is made available at www.cbs.dtu.dk/services/netoglyc.  相似文献
6.
Plants that are damaged by herbivorous arthropods provide carnivorous enemies of the herbivores with important information. They emit an induced volatile blend that is highly detectable to the carnivores from a distance. Such detectable signals that indicate herbivore presence are important for the carnivores because herbivores themselves are under strong selection not to expose themselves. In addition, carnivores would benefit from a specificity of the induced plant volatiles. Whether herbivore-induced plant volatiles are reliable indicators of herbivore identity, however, has not been resolved unambiguously. Some studies support the reliability of herbivore-induced plant volatiles, while others do not. Different approaches have been used such as chemical analysis, behavioural analysis or a combination of the two. Based on the total of chemical studies one might conclude that in most cases herbivore-induced plant volatiles are not very specific for the herbivore that damages the plant. However, arthropod chemosensors are much more sensitive than the detectors of analytical instruments. Therefore, chemical analyses are not suitable to demonstrate whether or not herbivore-induced plant volatiles are reliable indicators of herbivore identity to carnivores. Behavioural studies should provide this information. In analysing carnivore behaviour it should be realised, however, that arthropod behaviour can be highly variable. Arthropod foraging decisions are affected by external and internal factors such as (a) abiotic environmental factors, (b) presence of competitors or enemies, (c) deprivation of food or oviposition sites, (d) specific deprivation of certain nutrients or (e) learning. In this paper their effect on discrimination of carnivores between volatile blends emitted by plants infested by different herbivores is reviewed. This provides testable hypotheses of why discrimination was not found in some studies. The ability of carnivores to discriminate is likely to be more common than is clear to date, which should invoke functional studies of the conditions that influence the occurrence of this discrimination.  相似文献
7.
Role for brain-derived neurotrophic factor in learning and memory   总被引:23,自引:0,他引:23  
In addition to its actions on neuronal survival and differentiation, brain-derived neurotrophic factor (BDNF) has a role in the regulation of synaptic strength. Long-term potentiation, a form of synaptic plasticity, is markedly impaired in BDNF mutant mice, but the changes were restored by the re-expression of BDNF. BDNF also influences the development of patterned connections and the growth and complexity of dendrites in the cerebral cortex. These results suggest a role for BDNF in learning and memory processes, since memory acquisition is considered to involve both short-term changes in electrical properties and long-term structural alterations in synapses. Memory acquisition is associated with an increase in BDNF mRNA and TrkB receptor activation in specific brain areas. Moreover, the pharmacologic and genetic deprivation of BDNF or its receptor TrkB results in severe impairment of learning and memory in mice, rats and chicks. The effect of BDNF on learning and memory may be linked to the modulation of NMDA and non-NMDA receptor functions as well as the expression of synaptic proteins required for exocytosis. Activation of the mitogen-associated protein kinase and/or phosphatidylinositol 3-kinase signaling pathways may be involved in BDNF-dependent learning and memory formation. It is concluded that BDNF/TrkB signaling plays an important role in learning and memory.  相似文献
8.
老年大鼠学习记忆减退的神经基础   总被引:22,自引:0,他引:22  
洪岸 《生理科学进展》1995,26(3):240-242
对由Morris水迷宫分得的青年、老年记忆正常和记忆减退鼠的脑组织分别进行突触、AChE纤维、突触素、小白蛋白神经元以及突触体钙离子浓度、膜流动性的定量分析。结果表明老年记忆减退鼠新皮质、海马结构突触素含量、突触、胆碱能纤维、小白蛋白阳性神经元密度及突触体膜流动笥较老年记忆正常和青年鼠明显降低。老年记忆正常鼠与青年鼠各项均无显著差异。本研究提示各研究指标的异常与老年学习记忆减退密切相关。  相似文献
9.
慢性复合应激增强大鼠空间学习和记忆能力   总被引:22,自引:0,他引:22  
本文观察了慢性复合应激对大鼠学习与记忆功能的影响。实验采用成年 Wistar 大鼠, 将其随机分成应激组和对照组。采用垂直旋转、睡眠剥夺、噪音刺激和夜间光照4 种应激原, 无规律地交替刺激动物 6 周, 每天6 h, 制作慢性复合应激动物模型。采用 Morris 水迷宫和 Y- 迷宫测试大鼠学习与记忆成绩,并用 Cresyl violet 染色法对大鼠海马结构进行神经细胞计数。结果显示,应激组动物慢性复合应激后, 在 Morris 水迷宫内寻找隐蔽平台所需的时间(潜伏期)比对照组的明显地短(P<0.05), 表明应激鼠的空间记忆能力明显强于对照鼠;在 Y- 迷宫内寻找安全区的正确率比对照组的明显地高(P<0.05), 表明应激鼠的明暗分辨学习能力明显强于对照鼠; 应激鼠慢性复合应激后, 其海马结构齿状回、CA3 和CA1 区神经细胞密度极明显地高于对照鼠(P<0.001)。这些结果提示, 慢性复合应激可增强大鼠空间记忆能力和明暗分辨学习能力。本文并对慢性复合应激模式增强大鼠学习和记忆能力的可能原因进行了讨论。  相似文献
10.
Wei XL 《生理科学进展》2000,31(3):227-230
运用逆转录 多聚酶链反应 (RT PCR)技术及学习记忆行为实验 ,通过快速老化模型小鼠 (SAM )、氢化可的松处理小鼠及正常小鼠 ,研究发现海马糖皮质激素受体 (GR)、盐皮质激素受体 (MR)、bcl 2、c fos、神经细胞粘附分子 (NCAM )、早老蛋白 2 (PS 2 )及apoE与中枢学习记忆功能具有密切的关系。应用mRNA差异显示技术研究发现 ,SAM的快速老化亚系SAMP8和抗快速老化亚系SAMR1海马有 6条明显差异的基因片段 ,其中二个为新基因。口服六味地黄汤 (LW )对模型动物学习记忆功能衰退具有明显的改善作用 ,同时对海马基因表达异常具有明显纠正作用。应用胚胎大鼠原代培养的海马神经元研究发现皮质酮对学习记忆有关基因表达具有明显影响。上述结果提示 ,中枢学习记忆过程与海马多种基因表达存在密切的关系 ,纠正海马基因表达异常、调节下丘脑 垂体 肾上腺 (HPA)轴的平衡是LW益智作用的重要机制之一。  相似文献
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