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811.
B. J. Briscoe O. Lorge A. Wajs P. Dang 《Journal of Polymer Science.Polymer Physics》1998,36(13):2435-2447
The article reports on the behaviour of poly(vinylidene fluoride) in carbon dioxide at 42°C and 80°C and in a pressure range of 0.1–30 MPa. Experimental techniques for the measurement of gas mass uptake and polymer dilatation are described and the corresponding data are reported as mass sorption and dilatation isotherms, respectively. The mass uptake experiment was also used to follow the evolution of the coefficient of diffusion of carbon dioxide into the polymer as a function of pressure or concentration. An analysis for the calculation of the partial molar volume of carbon dioxide as a function of pressure is also given, which shows that the ‘apparent’ partial molar volume of the carbon dioxide decreases with pressure to very low values, at high pressure. The computed values are significantly less than those for either the liquid or the solid phases of pure carbon dioxide, and also lower than some data previously reported for silicone elastomers. A consideration of the origins of this apparent anomaly is given in the conclusions. © 1998 John Wiley & Sons, Inc. J. Polym. Sci. B Polym. Phys. 36: 2435–2447, 1998 相似文献
812.
The numerical method used in this study is the moving particle semi-implicit (MPS) method, which is based on particles and their interactions. The particle number density is implicitly required to be constant to satisfy incompressibility. A semi-implicit algorithm is used for two-dimensional incompressible non-viscous flow analysis. The particles whose particle number densities are below a set point are considered as on the free surface. Grids are not necessary in any calculation steps. It is estimated that most of computation time is used in generation of the list of neighboring particles in a large problem. An algorithm to enhance the computation speed is proposed. The MPS method is applied to numerical simulation of breaking waves on slopes. Two types of breaking waves, plunging and spilling breakers, are observed in the calculation results. The breaker types are classified by using the minimum angular momentum at the wave front. The surf similarity parameter which separates the types agrees well with references. Breaking waves are also calculated with a passively moving float which is modelled by particles. Artificial friction due to the disturbed motion of particles causes errors in the flow velocity distribution which is shown in comparison with the theoretical solution of a cnoidal wave. © 1998 John Wiley & Sons, Ltd. 相似文献
813.
814.
Synthesis and Crystal Structure of the Transition Metal Trimetaphosphimates Zn3[(PO2NH)3]2 · 14 H2O and Co3[(PO2NH)3]2 · 14 H2O The transition metal trimetaphosphimates Zn3[(PO2NH)3]2 · 14 H2O and Co3[(PO2NH)3]2 · 14 H2O were obtained by the reaction of an aqueous solution of Na3(PO2NH)3 · 4 H2O with the respective metal nitrate or halide (molar ratio 1 : 4). The structure of Zn3[(PO2NH)3]2 · 14 H2O was solved by single crystal X‐ray methods. The structure of isotypic Co3[(PO2NH)3]2 · 14 H2O was refined from X‐ray powder diffraction data using the Rietveld method (Zn3[(PO2NH)3]2 · 14 H2O ( 1 ): P 1, a = 743.7(2), b = 955.9(2), c = 980.1(2) pm, α = 102.70(3), β = 90.46(3), and γ = 100.12(3)°, Z = 1; Co3[(PO2NH)3]2 · 14 H2O ( 2 ): P 1, a = 746.05(1), b = 957.06(2), c = 988.51(2) pm, α = 102.162(1), β = 90.044(1), and γ = 99.258(1)°, Z = 1). In 1 and 2 the P3N3 rings of the trimetaphosphimate ions attain a conformation which can be described as a combination of an ideal boat and an ideal twist conformation. The trimetaphosphimate ions act as bridging ligands. Thus chains of alternating M2+ and (PO2NH)33– ions are formed which are interconnected by additional M2+ ions forming electro‐neutral double chains. In the solid these double chains are connected by hydrogen bonds. 相似文献
815.
The adsorption parameters (α) established for the monosubstituted acetylenic liquids in this investigation are consistent with expectation based on analogies with the log αf = log αi ‐ Ds(Nf − Ni) relationships reported earlier for the many homologous series of liquids ZR, in which Z is a functional group having strong affinity for the pendent phenyl group of polystyrene and R is an alkyl substituent that is varied systematically. The order of relative Z‐affinities, based on α for the respective ZCH2CH3 molecules, confirm that the nature of Z is the major factor that affects α and that electronic and steric contributions from R are modifying effects, which are reflected in Ds. Comparisons of the results observed for HCC(CH2)nZ′ liquids with those for HCC(CH2)nH and with analogous pairs of Z(CH2)nZ′ series confirm that Z′ at the other end of the polymethylene chain can have a moderate positive effect or a marked negative effect on α, depending on whether the mode of adsorption to pendent phenyl groups is mono‐ or bidentate. This study also confirms that a sharp reversal in the roles played by the molecules participating in the adsorption process occurs when all of the hydrogen atoms covalently bonded to the center of unsaturation are replaced by alkyl substituents. © 1999 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 37: 2611–2633, 1999 相似文献
816.
克拉玛依减渣热转化前后的溶解度参数研究 总被引:2,自引:2,他引:0
对克拉玛依减渣进行适度热转化,确定了其裂解深度最大且不结焦的条件。利用超临界萃取分馏技术,将克拉玛依减渣及其热转化残渣油分离成一系列窄馏分和萃余残渣,对窄馏分及萃余残渣的性质(相对分子质量、密度、残炭、C、H、N、S元素和金属元素等)进行了表征。用改进的方法测定了萃余残渣的溶解度参数,并根据性质计算了各个窄馏分的溶解度参数,克拉玛依减渣及其热转化残渣油萃余残渣的溶解度参数分别为18.27 MPa1/2和19.79 MPa1/2;从溶解度参数的角度解释了渣油加工过程中的分相、结焦等问题。 相似文献
817.
基于不同波长的光闪烁,采用修正的大气湍流Hill谱模型,提出了一种同时反演大气湍流内尺度及折射率结构常数的方法。假定内尺度在某一个范围内取值,对于不同波长的闪烁指数,如果当内尺度取某一定值时,由光传输理论计算的C2n(λ1,…)和C2n (λ2,…)相等,反演成功。根据此原理设计了三波长闪烁计并在某地进行了外场测量。近地面大气湍流的内尺度一般在2~10 mm之间,且随折射率结构常数(其量级为10-16~10-13)的变化而变化,两者之间存在一定的正相关;任意两波长组合进行反演得到的内尺度(或折射率结构常数)值具有自洽性,其相关系数的最小值为0.81,因此证明了该方法的可行性。 相似文献
818.
Occurrence of gear rattle in transmission systems can result in severe vibration and noise, which in applications such as automobiles is an important source of user discomfort. As a result , the reduction of the rattling noise has attracted lot of concerns. The rattling noise level is affected by several gearbox parameters, an understanding of which is essential to prevent the expensive design modifications at later stages of product development. To develop such understanding at the gearbox design stage, this paper analytically evaluates the gear parameters’ effect on the root mean square of the wheel gear acceleration under idling condition, which is known to be linearly correlated to the
rattling noise level. Therefore, this evaluation allows for an investigation of the gear parameters’ influence on the rattling noise as well. This method is then verified by comparing the analytical results with the simulation results from a dynamic model built in SIMPACK as well as previously published experimental results. Thus, the proposed analytical evaluation method can optimize the gearbox specifications at the design stage to reduce the gear rattle noise level. 相似文献
819.
820.
This paper is concerned with the flow of two immiscible fluids through a porous horizontal channel. The fluid in the upper region is the micropolar fluid/the Eringen fluid, and the fluid in the lower region is the Newtonian viscous fluid. The flow is driven by a constant pressure gradient. The presence of micropolar fluids introduces additional rotational parameters. Also, the porous material considered in both regions has two different permeabilities. A direct method is used to obtain the analytical solution of the concerned problem. In the present problem, the effects of the couple stress, the micropolarity parameter, the viscosity ratio, and the permeability on the velocity profile and the microrotational velocity are discussed. It is found that all the physical parameters play an important role in controlling the translational velocity profile and the microrotational velocity. In addition, numerical values of the different flow parameters are computed. The effects of the different flow parameters on the flow rate and the wall shear stress are also discussed graphically. 相似文献