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961.
周承倜 《应用数学和力学(英文版)》1991,12(2):113-120
In this paper,the general equations of dynamic stability for composite laminatedplates are derived by Hamilton principle.These general equations can be used to considerthose different factors that affect the dynamic stability of laminated plates.The factors aretransverse shear deformation,initial imperfections,longitudinal and rotational inertia,andply-angle of the fiber,etc.The solutions of the fundamental equations show that someimportant characteristics of the dynamic instability can only be got by the considerationand analysis of those factors 相似文献
962.
球形涂层粒子增强复合材料的有效模量 总被引:2,自引:0,他引:2
本文通过四相球模型和复合材料的等效介质理论,研究了球形涂层粒子增强复合材料的有效模量性质,得到了这种增强复合材料的有效体积模量和有效剪切模量的理论预测公式。这些结果在特殊情况下,可退化到三相球模型确定的球形粒子增强复合材料的有效模量公式。 相似文献
963.
PENG Xiao-gang ZHANG Xin-tong LI Lin-song QIN Zhu-jie XIAO Liang-zhi LI Tie-jin Shen Chao 《高等学校化学学报》1995,16(Z1):13
Nanoparticulate [PMo11Cu(H2O)O39]5--(PCuMo11)-n-C18H37NH2 composite monolayer can be formed at the air-liquid interface using nanoparticulate PCuMo11 as the subphase. The area extrapolated to π=0 is 0.27 nm2 per hydrocarbon chain of the monolayer. The collapse pressure is about 3.5×10-1 N. The composite monolayer was deposited on the solid substrate using the LB technique. The XPS characterization of the composite monolayer showed that in the film the directional alignment of PCuMo11, molecules was in the direction of Cu atoms close to the amino groups of the octadecylamine moleculos. 相似文献
964.
带裂纹层合板能量释放率分析 总被引:1,自引:1,他引:0
为了进一步了解裂纹尖端应力场的特性,本文对复合材料层合板的界面裂纹作了分析.文中强调了能量释放率分量存在的条件,并给出能量释放率分量和应力强度因子间的关系式.结合经典板理论的分析结果,根据外荷作用及某些几何参数和材料多数,导出了一般复合材料层合板的应力强度因子的封闭形式解.为了得到在一般荷载条件下能量释放率的分量,必须分别确定模型混合参数Ω,文中讨论了确定参数Ω的方法,最后,应用本文方法于几种不同种类的复合材料层合板,证明其结果可应用于工程实践. 相似文献
965.
再生纤维素膜(甘蔗渣浆制)表面直接用紫外光固化聚氨酯-丙烯酸酯制备出防水性复合膜。由红外光谱和扫描电镜研究了复合膜的结构。同时,测定了膜的防水性、力学性能、水汽透过性和尺寸稳定性。实验结果表明,当聚氨酯:丙烯酸酯为40:55(质量比),在400W紫外光下固化5min制得的复合膜具有致密的表面结构和较好的性能,该膜经水浸泡后其断裂强度可达干膜的90%,浸水收缩率和膨胀率均小于2.5%,水汽渗透量仅为再生纤维素膜的1/4.由此表明复合膜的防水性和尺寸稳定性明显提高。此外,该复合膜在可见光区的透光率在80%~90%之间,而且对紫外光有屏蔽作用。 相似文献
966.
自然复合材料的强韧化机理和仿生复合材料的研究 总被引:12,自引:0,他引:12
本文评述了一个新的研究方向─—自然复合材料强韧化的细观机理及其仿生复合材料的研究。着重考察了木、人骨、贝壳珍珠层、昆虫外骨骼及翅等自然复合材料的研究现状,基于这些研究,部分仿生材料已被设计和制造出来并达到商用程度.复合材料在细观层次的仿生,是将对复合材料及其结构设计产生潜在冲击的重要发展方向. 相似文献
967.
968.
B. Manz P. S. Chow L. F. Gladden 《Journal of magnetic resonance (San Diego, Calif. : 1997)》1999,136(2):226
A modified version of the echo-planar imaging technique incorporating a Carr–Purcell train of 180° rf pulses (PEPI) has been implemented on a standard spectrometer. It is demonstrated that artifacts in the image due to cumulative errors in the rf field can be reduced by replacing each 180° pulse by a composite sequence of three rf pulses. Artifact-free 3D images at 94 μm voxel resolution are obtained within 15 min. This technique has been applied to study the drying process in an initially water-saturated model porous medium with characteristicT*2of order 700 μs. 相似文献
969.
H. Nélisse C. Bourbonnais H. Touchette Y.M. Vilk A.-M.S. Tremblay 《The European Physical Journal B - Condensed Matter and Complex Systems》1999,12(3):351-365
The temperature-dependent uniform magnetic susceptibility of interacting electrons in one dimension is calculated using several
methods. At low temperature, the renormalization group reveals that the Luttinger liquid spin susceptibility approaches zero temperature with an infinite slope in striking contrast with the Fermi liquid result and with the behavior
of the compressibility in the absence of umklapp scattering. This effect comes from the leading marginally irrelevant operator,
in analogy with the Heisenberg spin 1/2 antiferromagnetic chain. Comparisons with Monte Carlo simulations at higher temperature
reveal that non-logarithmic terms are important in that regime. These contributions are evaluated from an effective interaction
that includes the same set of diagrams as those that give the leading logarithmic terms in the renormalization group approach.
Comments on the third law of thermodynamics as well as reasons for the failure of approaches that work in higher dimensions
are given.
Received 2 March 1999 相似文献
970.
Following previous works [1, 2], silica–polystyrene core–shell particles have been synthesized by dispersion polymerization
of styrene in an ethanol/water mixture in the presence of a poly(styrene-b-ethylene oxide) block copolymer as stabilizer. Besides the formation of composite core–shell particles, a large number of
free latex particles that do not contain silica were also formed. This number decreases as the size of the silica beads decreases
from 300 to 29 nm in diameter, and becomes very low compared to the number of composite particles for the smallest silica
beads used. In every case, the composite particles could be easily separated from the free latex particles by centrifugation,
providing a material made of regular core–shell composite particles. On the basis of the mechanisms involved in dispersion
polymerization, hypotheses were formulated to account for the formation of the silica–polystyrene composite particles.
Received: 6 May 1999 Accepted in revised form: 29 June 1999 相似文献