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91.
Ascorbic acid prevents loss of Dlk1-Dio3 imprinting and facilitates generation of all-iPS cell mice from terminally differentiated B cells 总被引:1,自引:0,他引:1
Stadtfeld M Apostolou E Ferrari F Choi J Walsh RM Chen T Ooi SS Kim SY Bestor TH Shioda T Park PJ Hochedlinger K 《Nature genetics》2012,44(4):398-405, S1-2
92.
TSK动态网络及其在非线性动态系统中的应用 总被引:1,自引:1,他引:1
针对非线性动态系统特点,提出了一种新型的基于TSK模糊模型的动态回归模糊神经网DRFNN(Dynamic recurrent fuzzy neural networks),并给出了网络参教的迭代算法和基于李亚普诺夫稳定理论的收敛性证明。该动态回归网络由静态网络和内反馈动态回归网络组成,在结构上更好的拟合了非线性动态系统特点,应用于非线性动态系统的辨识和控制的试验结果也说明该动态回归模糊神经网络对解决非线性动态系统辨识和控制问题的有效性。 相似文献
93.
三轴高精度虚拟仿真转台研究 总被引:2,自引:1,他引:2
提出了三轴虚拟仿真转台系统的基本体系结构及其功能特点。文中着重阐述了虚拟仿真转台系统中的PDIVL,CAD,CAE技术、数据引擎、虚拟装配技术和虚拟样机等技术'同时详细论述了虚拟仿真转台系统的运行方式以及功能结构,其中包括基于PDM技术加以开发、设计转台机械结构并进行图纸管理和生产过程管理;运用OpenGL动画技术和虚拟装配理论实现模型的动态装配;运用虚拟样机技术实现了转台系统的机械结构模型与复杂控制模型的联合分析,实时调节与优化机械结构或控制率来提高系统的机械与控制性能,极大缩短真实转台系统的开发周期。 相似文献
94.
非线性控制系统半实物仿真技术研究 总被引:1,自引:1,他引:1
设计一非线形控制半实物仿真系统对非线型控制算法进行验证,并给出控制推力所需总冲的数学模型,分析了此非线形控制半实物仿真系统的误差,文中还通过型号仿真试验所得到的试验结果对非线形控制系统的设计进行了正确性验证,而且在试验过程中完善了控制系统的设计,同时也验证了该类仿真系统的正确性及仿真系统误差分析的正确性,该半实物仿真系统的建立对同类非线形控制半实物仿真系统的建立具有一定一的借鉴作用。 相似文献
95.
针对三维目标(3D object)检索问题,提出了一种基于混合描述符及多支持向量机融合相关反馈学习的3D目标检索方法。在分析现行3D模型检索方法的基础上,提出了混合描述符HD及相关反馈学习的总体思路。讨论了HD框架构建,即在光场图像阵列自适应聚类基础上,分别实现HD各个子描述符。讨论了基于多支持向量机的融合分类学习机制,并将其用于3D目标检索反馈学习环节,对HD检索性能及相关反馈学习分类进行了实验分析,结果表明所提出的方法是有效的。 相似文献
96.
Autosomal recessive lissencephaly with cerebellar hypoplasia is associated with human RELN mutations 总被引:20,自引:0,他引:20
Hong SE Shugart YY Huang DT Shahwan SA Grant PE Hourihane JO Martin ND Walsh CA 《Nature genetics》2000,26(1):93-96
Normal development of the cerebral cortex requires long-range migration of cortical neurons from proliferative regions deep in the brain. Lissencephaly ("smooth brain," from "lissos," meaning smooth, and "encephalos," meaning brain) is a severe developmental disorder in which neuronal migration is impaired, leading to a thickened cerebral cortex whose normally folded contour is simplified and smooth. Two identified lissencephaly genes do not account for all known cases, and additional lissencephaly syndromes have been described. An autosomal recessive form of lissencephaly (LCH) associated with severe abnormalities of the cerebellum, hippocampus and brainstem maps to chromosome 7q22, and is associated with two independent mutations in the human gene encoding reelin (RELN). The mutations disrupt splicing of RELN cDNA, resulting in low or undetectable amounts of reelin protein. LCH parallels the reeler mouse mutant (Reln(rl)), in which Reln mutations cause cerebellar hypoplasia, abnormal cerebral cortical neuronal migration and abnormal axonal connectivity. RELN encodes a large (388 kD) secreted protein that acts on migrating cortical neurons by binding to the very low density lipoprotein receptor (VLDLR), the apolipoprotein E receptor 2 (ApoER2; refs 9-11 ), alpha3beta1 integrin and protocadherins. Although reelin was previously thought to function exclusively in brain, some humans with RELN mutations show abnormal neuromuscular connectivity and congenital lymphoedema, suggesting previously unsuspected functions for reelin in and outside of the brain. 相似文献
97.
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99.
Non-haem Fe(II)/alpha-ketoglutarate (alphaKG)-dependent enzymes harness the reducing power of alphaKG to catalyse oxidative reactions, usually the hydroxylation of unactivated carbons, and are involved in processes such as natural product biosynthesis, the mammalian hypoxic response, and DNA repair. These enzymes couple the decarboxylation of alphaKG with the formation of a high-energy ferryl-oxo intermediate that acts as a hydrogen-abstracting species. All previously structurally characterized mononuclear iron enzymes contain a 2-His, 1-carboxylate motif that coordinates the iron. The two histidines and one carboxylate, known as the 'facial triad', form one triangular side of an octahedral iron coordination geometry. A subclass of mononuclear iron enzymes has been shown to catalyse halogenation reactions, rather than the more typical hydroxylation reaction. SyrB2, a member of this subclass, is a non-haem Fe(II)/alphaKG-dependent halogenase that catalyses the chlorination of threonine in syringomycin E biosynthesis. Here we report the structure of SyrB2 with both a chloride ion and alphaKG coordinated to the iron ion at 1.6 A resolution. This structure reveals a previously unknown coordination of iron, in which the carboxylate ligand of the facial triad is replaced by a chloride ion. 相似文献
100.
An autosomal transcript in skeletal muscle with homology to dystrophin 总被引:46,自引:0,他引:46
D R Love D F Hill G Dickson N K Spurr B C Byth R F Marsden F S Walsh Y H Edwards K E Davies 《Nature》1989,339(6219):55-58