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991.
利用低温水热法生长的ZnO纳米棒(ZnO-NRs),和p型有机半导体材料聚[2-甲氧基-5-(2-乙基己氧基)-1,4-苯撑乙烯撑](MEH-PPV)复合制备了结构为“ITO/ZnO晶种/ZnO-NRs/MEH-PPV/Al”的发光器件。测试结果发现,该器件具有非常好的二极管整流特性。对ZnO-NRs/M EH-PPV异质结施加超过17 V的反向偏压时,可同时获得两种半导体材料的发光,且ZnO近紫外光(380 nm )发射强度远大于 M EH-PPV的红橙光强度,发光功率随着反向偏压的增加迅速增强,然而施加正向偏压时未探测到发光。该器件的发光机理不同于其他文献报道的正偏压发光,而属于反偏压发光器件,其发光机理归因于有机无机复合异质结的界面特殊性和ZnO-NRs的纳米尺寸效应,反偏压下器件实现的是载流子隧穿发光,而正偏压时载流子以表面态的无辐射复合及漏电流方式消耗。 相似文献
992.
993.
在MTT口袋模型的基础上采用密度依赖口袋常数,给出了奇异夸克物质的热力学关系,并用于描述奇异夸克物质及混合星内的夸克相,研究了奇异星、混合星的性质.结果表明,密度依赖口袋常数下,奇异夸克物质的压强公式中有一个附加项,而能量密度中则没有,从而保证了系统的热力学自洽性.在新的热力学关系下,奇异夸克物质的状态方程变软,相应的奇异星的引力质量和对应的半径均变小;混合星的状态方程也变软,其质量变小,而对应的半径也变小.说明经热力学自洽处理后该模型对中子星的状态方程及相应的质量-半径关系等都有显著的影响. 相似文献
994.
密度矩阵重正化群方法(DMRG)在求解一维强关联格点模型的基态时可以获得较高的精度,在应用于二维或准二维问题时,要达到类似的精度通常需要较大的计算量与存储空间.本文提出一种新的DMRG异构并行策略,可以同时发挥计算机中央处理器(CPU)和图形处理器(GPU)的计算性能.针对最耗时的哈密顿量对角化部分,实现了数据的分布式存储,并且给出了CPU和GPU之间的负载平衡策略.以费米Hubbard模型为例,测试了异构并行程序在不同DMRG保留状态数下的运行表现,并给出了相应的性能基准.应用于4腿梯子时,观测到了高温超导中常见的电荷密度条纹,此时保留状态数达到104,使用的GPU显存小于12 GB. 相似文献
995.
This paper is concerned with the integration by parts formulae for the pinned or the standard Wiener measures restricted on
a space of paths staying between two curves. The boundary measures, concentrated on the set of paths touching one of the curves
once, are specified. Our approach is based on the polygonal approximations. In particular, to establish the convergence of
boundary terms, a uniform estimate is derived by means of comparison argument for a sequence of random walks conditioned to
stay between two polygons. Applying the Brascamp–Lieb inequality, the stochastic integrals of Wiener type are constructed
relative to the three-dimensional Bessel bridge or the Brownian meander.
Supported in part by the JSPS Grant (B)(1)14340029 相似文献
996.
Frederic Paik Schoenberg 《Annals of the Institute of Statistical Mathematics》2002,54(2):445-457
The process obtained by rescaling a homogeneous Poisson process by the maximum likelihood estimate of its intensity is shown to have surprisingly strong self-correcting behavior. Formulas for the conditional intensity and moments of the rescaled Poisson process are derived, and its behavior is demonstrated using simulations. Relationships to the Brownian bridge are explored, and implications for point process residual analysis are discussed. 相似文献
997.
998.
To simplify the definition of fuzzy systems or to reduce its complexity hierarchical structures can be used. Thus, more transparent rule bases that are also easier to maintain can be designed. Furthermore, it is sometimes necessary to use time delayed input or to reuse time delayed output from the fuzzy system itself to obtain a rule base that describes the analyzed problem appropriately. This leads to hierarchical recurrent architectures that have increased approximation capabilities since they are able to store information of the past. In this article we present a neuro-fuzzy model that can be used to optimize hierarchical recurrent fuzzy rule bases if training data is available. Furthermore, we present an approach to learn initial rule bases from data using rule templates. 相似文献
999.
F. Cros L. Malier J.-P. Korb F. Chaput 《Journal of Sol-Gel Science and Technology》1998,13(1-3):457-460
A new experimental approach to study the porosity of hybrid organic-inorganic glasses is reported. It relies upon nuclear magnetic resonance observation of molecular guest dynamics. It is shown that in MTEOS xerogels, there exists an interconnected organic-rich network in which organic guests are trapped and can eventually diffuse. The interpore translational diffusion is strongly activated and its spatial extension gives information on the pore connectivity, whose decay is characterized by the interpore jump probability given by the theoretical model. 相似文献
1000.
Four different silica-based urea-formaldehyde (UF/SiO2) composite materials were prepared by various sol-gel synthetic procedures to yield an interpenetrating (IPN-UF/SiO2), a micro-size UF resin encapsulated inside silica shell (Encap-UF/SiO2), a micro-size silica encapsulated inside UF shell (Encap-SiO2/UF), and a blend mixture (Blend-UF/SiO2) hybrid systems. The thermal properties of the obtained organic-inorganic hybrid composite materials were examined by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The structure and morphology of the obtained systems were investigated by infrared spectroscopy (FT-IR), powder X-ray diffraction (XRD) and scanning electron microscopy (SEM) techniques. Their surface porosity and acidity were evaluated from the nitrogen adsorption isotherm and the pH of the corresponding 10% aqueous suspension, respectively. All the results provided evidence for the formation of different hybrid systems with different surface, structural and morphological characteristics. 相似文献