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61.
    
The particulate emission caused by welding of steel plates covered with 29 diversified shop primers has been investigated. The investigation includes the determination of particle mass, particle size distribution, and of the contents of heavy metals such as lead and cadmium. The results show that all investigated primers except those with high concentration of zinc pigment produce mass emissions which are very low in comparison to manual arc welding with covered electrode and CO2-welding on uncoated steel. The emitted particles of the primers are smaller than 1 μm particle diameter and therefore respirable. Lead and cadmium was found in particles emitted during the welding process of all investigated primers. The highest amount was found in particles of primers with high contents of zinc and ferric oxide.  相似文献   
62.
利用积分方法对多种电流剖面下HL2A装置单零偏滤器位形特征进行了计算研究。积分方法的优点是可以在任意电流剖面下求解具有X-点的自由边界的Grad-Shafranov方程。对HL2A装置而言,大体上可以在合理设定的分界面形状下,经几次叠代计算出各组极向场线圈(垂直场,三对多极场和多极补偿场以及水平场)中的电流。HL-2A的单零偏滤器位形基本上是圆截面加上在X-点附近的局部形变。对刮离区和偏滤器靶板区磁力线特性进行了分析以确定偏滤器的品质。  相似文献   
63.
Properties of the thermal radiation from arbitrary fractional dimension are investigated. Generalized blackbody radiation for arbitrary dimension can be obtained and the energy density is shown as a function of arbitrary dimension as well as temperature. Maximum frequency factor representing the relation between most probable photon energy and thermal energy is shown as a function of arbitrary fractional dimension. It is also shown how to measure the arbitrary fractional dimension of the body with thermal radiation.  相似文献   
64.
65.
We present a new cell-centered multi-material arbitrary Lagrangian–Eulerian (ALE) scheme to solve the compressible gas dynamics equations on two-dimensional unstructured grid. Our ALE method is of the explicit time-marching Lagrange plus remap type. Namely, it involves the following three phases: a Lagrangian phase wherein the flow is advanced using a cell-centered scheme; a rezone phase in which the nodes of the computational grid are moved to more optimal positions; a cell-centered remap phase which consists of interpolating conservatively the Lagrangian solution onto the rezoned grid. The multi-material modeling utilizes either concentration equations for miscible fluids or the Volume Of Fluid (VOF) capability with interface reconstruction for immiscible fluids. The main original feature of this ALE scheme lies in the introduction of a new mesh relaxation procedure which keeps the rezoned grid as close as possible to the Lagrangian one. In this formalism, the rezoned grid is defined as a convex combination between the Lagrangian grid and the grid resulting from condition number smoothing. This convex combination is constructed through the use of a scalar parameter which is a scalar function of the invariants of the Cauchy–Green tensor over the Lagrangian phase. Regarding the cell-centered remap phase, we employ two classical methods based on a partition of the rezoned cell in terms of its overlap with the Lagrangian cells. The first one is a simplified swept face-based method whereas the second one is a cell-intersection-based method. Our multi-material ALE methodology is assessed through several demanding two-dimensional tests. The corresponding numerical results provide a clear evidence of the robustness and the accuracy of this new scheme.  相似文献   
66.
Loss and dispersion characteristics of groove guide are two practically important factors in the design for millimeter wave system consisting of groove guide. In this paper, a new method is presented for analyzing loss and dispersion characteristics of the groove guides with arbitrary groove cross-sections. The method is based on the combination of an equivalent active transmission line equation and the staircase approximation. Numerical results of dispersion and attenuation properties for some groove guides with different groove profiles are given. The effectiveness and practicality of the present analysis are confirmed by the data given in the literature.*Supported by the National Natural Science Foundation of China (No. 60171019) and (No. 60371010)  相似文献   
67.
We propose a tripartite scheme for bisplitting an arbitrary single-qubit quantum information (QI) by using a class of asymmetric three-qubit W state as quantum channels. In the scheme, the sender Alice first performs a Bell-state measurement on her two qubits and then publishes her measurement result via a public classical channel. Based on Alice’s message, if the two receivers Bob and Charlie collaborate together, they can retrieve the QI, i.e., they can deterministically recover the QI in one receiver’s site by first performing a two-qubit unitary operation and then executing a single-qubit unitary operation. Afterwards, we sketch the extension of the single-qubit QI splitting to an arbitrary N-qubit QI splitting.  相似文献   
68.
    
Triplex forming oligonucleotides are used as a tool for gene regulation and in DNA nanotechnology. By incorporating artificial nucleic acids, target affinity and biological stability superior to that of natural DNA may be obtained. This work demonstrates how a chimeric clamp consisting of acyclic (L)-threoninol nucleic acid (aTNA) and DNA can bind DNA and RNA by the formation of a highly stable triplex structure. The (L)-aTNA clamp is released from the target again by the addition of a releasing strand in a strand displacement type of reaction. It is shown that the clamp efficiently inhibits Bsu and T7 RNA polymerase activity and that polymerase activity is reactivated by displacing the clamp. The clamp was successfully applied to the regulation of luciferase expression by reversible binding to the mRNA. When targeting a sequence in the double stranded plasmid, 40 % downregulation of protein expression is achieved.  相似文献   
69.
Using spherical coordinates, the coupling nonlin- ear dynamic system of a liquid-filled spherical tank, which can be excited discretionarily, is deduced by the H-O variational principle, and the viscous damping is introduced via the liquid dissipation function. The kinetic equations of the coupling system are deduced by the relationship between the velocity of liquid particles and the disturbed liquid surface equation. Normal differential equations are obtained through the Galerkin method. An equivalent mechanical model is developed for liquid sloshing in a spherical tank subject to arbitrary excitation. The fixed and slosh masses, as well as the spring and damping constants, are determined in such a way as to satisfy the principle of equivalence. Numerical simulations illustrate the theoretical results in this paper as well.  相似文献   
70.
A method for obtaining localized spectra from arbitrarily shaped regions of interest is described. When a sample consists of homogeneous compartments or domains, spectra localized in each compartment can be obtained from signals of single voxels with regular shapes by solving a set of simultaneous linear equations. Experimental demonstrations on a phantom and on human brain in vivo for a two compartment, two voxel case are presented. The issue of signal-to-noise ratio is also discussed.  相似文献   
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