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31.
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建立了考虑损伤的求解靶板阻力的理论模型,以此来评估陶瓷靶板的抗侵彻能力;数值模拟了长杆弹侵彻氧化铝陶瓷靶的破坏特性,结合实验结果确定了氧化铝陶瓷本构模型中的材料参数。建立了聚能射流侵彻氧化铝陶瓷靶的计算模型,对射流的形成机理及氧化铝陶瓷靶的抗侵彻性能进行研究,讨论了药型罩的几何尺寸对所形成的射流速度及侵彻深度的影响。结果表明:药型罩的锥角和壁厚增大,射流速度减小,壁厚对射流速度梯度的影响较大;同样,药型罩的锥角对侵彻深度也有较大的影响。 相似文献
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A. Edgar G. V. M. Williams M. Secu S. Schweizer J. -M. Spaeth 《Radiation measurements》2004,38(4-6):413-416
The turbidity, photoluminescence, and photo-stimulated luminescence (PSL) of fluorozirconate glass containing barium chloride nano- and micro-crystals have been measured for samples prepared by isochronal (70 min) annealing over a temperature range of 220–283°C, and correlated with the microstructure as determined by X-ray diffraction measurements. Crystallization of hexagonal phase barium chloride commences at around 220°C, but until 275°C the material retains excellent transparency although it displays negligible PSL. Between 275°C and 277°C, the hexagonal phase converts to the orthorhombic phase, the transparency abruptly decreases, and the PSL rises to a value of around 13% of that found for the commercial storage phosphor BaFBr:Eu. For a slightly higher temperature of 280°C, new phases appear which correspond to the onset of bulk crystallization, and at 283°C the relative PSL rises to 33%, while the transparency falls further. The trade-off between optical transparency and PSL over this narrow temperature window for X-ray imaging plate applications is briefly discussed. 相似文献
36.
An original set-up is used to study the adhesive properties of two hemispherical soap bubbles put into contact. The contact
angle at the line connecting the three films is extracted by image analysis of the bubbles profiles. After the initial contact,
the angle rapidly reaches a static value slightly larger than the standard 120° angle expected from Plateau rule. This deviation is consistent with previous experimental and theoretical studies: it can
be quantitatively predicted by taking into account the finite size of the Plateau border (the liquid volume trapped at the
vertex) in the free energy minimization. The visco-elastic adhesion properties of the bubbles are further explored by measuring
the deviation Δθd(t) of the contact angle from the static value as the distance between the two bubbles supports is sinusoidally modulated. It
is found to linearly increase with Δr
c/r
c , where rc is the radius of the central film and Δr
c the amplitude of modulation of this length induced by the displacement of the supports. The in-phase and out-of-phase components
of Δθd(t) with the imposed modulation frequency are systematically probed, which reveals a transition from a viscous to an elastic
response of the system with a crossover pulsation of the order 1rad · s^-1. Independent interfacial rheological measurements,
obtained from an oscillating bubble experiment, allow us to develop a model of dynamic adhesion which is confronted to our
experimental results. The relevance of such adhesive dynamic properties to the rheology of foams is briefly discussed using
a perturbative approach to the Princen 2D model of foams. 相似文献
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Johannes Wilden 《Applied Surface Science》2007,254(4):1067-1072
The free-form net shape laser synthesis of nanostructured ceramics from liquid precursors enables a residual stress-free production of high temperature resistant ceramic units and components for the use in microsystem engineering. Due to the use of molecular compounded liquid, ceramic precursors the resulting ceramic components show outstanding properties, for example high purity and a nanostructured material design.The use of pulsed lasers enables a defined input of energy required to pyrolyse the precursor material into a crystalline ceramic, so the active volume can be reduced significantly compared to other processes, for example pyrolysis by furnace.In this paper several methods for a further minimization of the active volume are presented. The investigations determined different factors affecting the process. Realizing selective experiments allows a determination of their influencing level and the definition of a working area to produce three-dimensional components with high aspect ratio.By several studies, e.g., scanning electron microscopy, transmission electron microscopy as well as X-ray diffraction analysis, the atomic structure and composition of the created components were analyzed and valued, so the different reaction processes can be described extensively. 相似文献