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排序方式: 共有154条查询结果,搜索用时 31 毫秒
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Seo MD Velamakanni S Ishiyama N Stathopulos PB Rossi AM Khan SA Dale P Li C Ames JB Ikura M Taylor CW 《Nature》2012,483(7387):108-112
Inositol-1,4,5-trisphosphate receptors (InsP(3)Rs) and ryanodine receptors (RyRs) are tetrameric intracellular Ca(2+) channels. In each of these receptor families, the pore, which is formed by carboxy-terminal transmembrane domains, is regulated by signals that are detected by large cytosolic structures. InsP(3)R gating is initiated by InsP(3) binding to the InsP(3)-binding core (IBC, residues 224-604 of InsP(3)R1) and it requires the suppressor domain (SD, residues 1-223 of InsP(3)R1). Here we present structures of the amino-terminal region (NT, residues 1-604) of rat InsP(3)R1 with (3.6??) and without (3.0??) InsP(3) bound. The arrangement of the three NT domains, SD, IBC-β and IBC-α, identifies two discrete interfaces (α and β) between the IBC and SD. Similar interfaces occur between equivalent domains (A, B and C) in RyR1 (ref. 9). The orientations of the three domains when docked into a tetrameric structure of InsP(3)R and of the ABC domains docked into RyR are remarkably similar. The importance of the α-interface for activation of InsP(3)R and RyR is confirmed by mutagenesis and, for RyR, by disease-causing mutations. Binding of InsP(3) causes partial closure of the clam-like IBC, disrupting the β-interface and pulling the SD towards the IBC. This reorients an exposed SD loop ('hotspot' (HS) loop) that is essential for InsP(3)R activation. The loop is conserved in RyR and includes mutations that are associated with malignant hyperthermia and central core disease. The HS loop interacts with an adjacent NT, suggesting that activation re-arranges inter-subunit interactions. The A domain of RyR functionally replaced the SD in full-length InsP(3)R, and an InsP(3)R in which its C-terminal transmembrane region was replaced by that from RyR1 was gated by InsP(3) and blocked by ryanodine. Activation mechanisms are conserved between InsP(3)R and RyR. Allosteric modulation of two similar domain interfaces within an N-terminal subunit reorients the first domain (SD or A domain), allowing it, through interactions of the second domain of an adjacent subunit (IBC-β or B domain), to gate the pore. 相似文献
24.
A total of 18 spider mite species belonging to 10 genera of the family Tetranychidae (Acari: Prostigmata) are reported from different provinces of Saudi Arabia (SA). Among these, two new species, Sonotetranychus madinahensis sp. nov. and Tetranychus salicornicus sp. nov., belonging to the subfamily Tetranychinae are described and illustrated. Also, five genera and 11 species are new to the mite fauna of SA. The distribution and host data of all recorded species in the current study are provided. A key to all spider mite species of SA is provided as well as a key to the species of the armenychus species group of the genus Tetranychus Dufour, based on males.
www.zoobank.org/urn:lsid:zoobank.org:pub:C41BB3ED-99D5-4DCF-B557-09526FA7D56B 相似文献
25.
Syed Furqan Rafique Jianhua Zhang Muhammad Hanan Waseem Aslam Atiq Ur Rehman Zmarrak Wali Khan 《清华大学学报》2018,(3)
This study provides details of the energy management architecture used in the Goldwind microgrid test bed. A complete mathematical model, including all constraints and objectives, for microgrid operational management is first described using a modified prediction interval scheme. Forecasting results are then achieved every 10 min using the modified fuzzy prediction interval model, which is trained by particle swarm optimization.A scenario set is also generated using an unserved power profile and coverage grades of forecasting to compare the feasibility of the proposed method with that of the deterministic approach. The worst case operating points are achieved by the scenario with the maximum transaction cost. In summary, selection of the maximum transaction operating point from all the scenarios provides a cushion against uncertainties in renewable generation and load demand. 相似文献
26.
Computationally efficient locality-aware interconnection topology for multi-processor system-on-chip (MP-SoC) 总被引:1,自引:0,他引:1
Khan Haroon-Ur-Rashid Shi Feng Ji WeiXing Gao YuJin Wang YiZhuo Liu CaiXia Deng Ning Li JiaXin 《科学通报(英文版)》2010,55(29):3363-3371
This paper evaluates the Triplet Based Architecture, TriBA – a new idea in chip multiprocessor architectures and a class of Direct Interconnection Network (DIN). TriBA consists of a 2D grid of small, programmable processing units, each physically connected to its three neighbors so that advantageous features of group locality can be fully and efficiently utilized. Any communication model can be well characterized by locality properties and, any topology has its intrinsic, structural, locality characteristics. We propose a new criterion in performance evaluation that is based on the concept of locality in an interconnection network, the “lower layer complete connect”. Our proposed criterion depicts how completely a processing node is connected to all its neighbors. TriBA is compared with 2D Mesh and Binary Tree as static interconnection network. The comparison / evaluation is enumerated from three orthogonal view points, viz., computational speed, physical layout and cost. Our analysis concludes that TriBA is computationally efficient interconnection strategy that exploits group locality in processing nodes. 相似文献
27.
Effect of deep cryogenic treatment on the formation of nano-sized carbides and the wear behavior of D2 tool steel 下载免费PDF全文
The effect of deep cryogenic treatment on the microstructure, hardness, and wear behavior of D2 tool steel was studied by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), hardness test, pin-on-disk wear test, and the reciprocating pin-on-flat wear test. The results show that deep cryogenic treatment eliminates retained austenite, makes a better carbide distribution, and increases the carbide content. Furthermore, some new nano-sized carbides form during the deep cryogenic treatment, thereby increasing the hardness and improving the wear behavior of the samples. 相似文献
28.
The effect of deep cryogenic treatment on the mechanical properties of 80CrMo12 5 tool steel was investigated. Moreover, the effects of stabilization (holding at room temperature for some periods before deep cryogenic treatment) and tempering before deep cryogenic treatment were studied. The results show that deep cryogenic treatment can eliminate the retained austenite, making a better carbide distribution and a higher carbide amount. As a result, a remarkable improvement in wear resistance of cryogenically treated specimens is observed. Moreover, the ultimate tensile strength increases, and the toughness of the sample decreases. It is also found that both stabilization and tempering before deep cryogenic treatment decrease the wear resistance, hardness, and carbides homogeneity compared to the deep cryogenically treated samples. It is concluded that deep cryogenic treatment should be performed without any delay on samples after quenching to reach the highest wear resistance and hardness. 相似文献
29.
Shan-jie Yi Hai-qing Yini Ke Chen Dil-Faraz Khan Qing-jun Zheng Xuan-hui Qui 《矿物冶金与材料学报》2013,20(11):1115-1121
Powder injection molding (PIM) and die pressing were employed to fabricate nano-TiN modified Ti(C,N)- based cermets. The shrinkage behavior, microstructure, porosity, and mechanical properties of the samples with and without nano-TiN addition fabricated by PIM and die pressing were analyzed. It is demonstrated that for either PIM or die pressing, the porosities are obviously reduced, the mechanical properties are significantly improved after adding nano-TiN, and the hard particles are refined; the rim phase thickness obviously becomes thinner, and the number of dimples in fracture also increases. Compared the samples fabricated by die pressing, it is difficult for PIM to obtain dense Ti(C,N)-based cermets. Due to the too much existence of pores and isolated carbon, the mechanical properties of the sintered samples by PIM are inferior to those of the sintered ones by die pressing. 相似文献
30.
ZnO and Cr-doped ZnO thin films are grown on to glass substrates using reactive electron beam(e-beam) evaporation technique.Variation of structural,morphological,and optical properties with Cr doping is investigated.X-ray diffraction(XRD) studies show that the films are polycrystalline in nature with single phase.Energy dispersive spectroscopy(EDS) results demonstrate that Cr ions are substitutionally incorporated into ZnO.Atomic force microscopy(AFM) reveals that the films present a compact surface and root mean squared(RMS) roughness increased with Cr contents.The optical band gap energy Eg of the films has been determined using Transmission data by spectrophotometer and ellipsometry.The band gap energy found to be decreased with increasing Cr doping concentration.The optical constants(refractive index,extinction coefficient) are calculated using ellipsometry and found to increase with Cr doping concentration. 相似文献