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1.
Summary A program is described which calculates the number of effective plates and the coating efficiency over the entire range of a test chromatogram. The peak widths at half height are derived by assuming a Gaussian peak shape. The interpolated peak width at k=4 is used for computing a standardized number of effective plates. Plate height, column permeability, overall performance and a novel parameter called sampling efficiency are calculated from 5 other figures — i. e. carrier gas code, pressure drop, column length, column temperature and particle size.Dedicated to Dr. Leslie S. Ettre for his 60th birthday.  相似文献   
2.
The possibilities for developing devices on the basis of superionic conductors for measuring and providing advance electric energy consumption and determining the integral index of luminous energy are considered. It is experimentally shown that the consumed charge and the illumination intensity in a certain time interval can be measured without feeding power to the devices. The measuring transducers are easy to design and realize. The reliability and reproducibility of results are supported.  相似文献   
3.
We have developed a time-reversible rigid-body (rRB) molecular dynamics algorithm in the isothermal-isobaric (NPT) ensemble. The algorithm is an extension of rigid-body dynamics [Matubayasi and Nakahara, J Chem Phys 1999, 110, 3291] to the NPT ensemble on the basis of non-Hamiltonian statistical mechanics [Martyna, G. J. et al., J Chem Phys 1994, 101, 4177]. A series of MD simulations of water as well as fully hydrated lipid bilayer systems have been undertaken to investigate the accuracy and efficiency of the algorithm. The rRB algorithm was shown to be superior to the state-of-the-art constraint-dynamics algorithm SHAKE/RATTLE/ROLL, with respect to computational efficiency. However, it was revealed that both algorithms produced accurate trajectories of molecules in the NPT as well as NVT ensembles, as long as a reasonably short time step was used. A couple of multiple time-step (MTS) integration schemes were also examined. The advantage of the rRB algorithm for computational efficiency increased when the MD simulation was carried out using MTS on parallel processing computer systems; total computer time for MTS-MD of a lipid bilayer using 64 processors was reduced by about 40% using rRB instead of SHAKE/RATTLE/ROLL.  相似文献   
4.
Oustaloup recursive approximation (ORA) is widely used to find a rational integer-order approximation for fractional-order integrators and differentiators of the form sv, v ∈ (−1, 1). In this method the lower bound, the upper bound and the order of approximation should be determined beforehand, which is currently performed by trial and error and may be inefficient in some cases. The aim of this paper is to provide efficient rules for determining the suitable value of these parameters when a fractional-order PID controller is used in a stable linear feedback system. Two numerical examples are also presented to confirm the effectiveness of the proposed formulas.  相似文献   
5.
针对甲烷在大气中背景气体成分复杂、检测难度大、稳定性差等问题,本文基于可调谐二极管激光吸收光谱技术和波长调制光谱技术,将积分梳状滤波器与有限脉冲响应滤波器相结合应用于数字正交锁相放大器,开展大气中甲烷气体的痕量检测实验研究.实验表明,与传统的数字正交锁相放大器相比较,改进的数字正交锁相放大器提取的二次谐波信号的信噪比从...  相似文献   
6.
This article illustrates practical applications to molecular dynamics simulations of the recently developed numerical integrators [Phys Rev E 2006, 73, 026703] for ordinary differential equations. This method consists of extending any set of ordinary differential equations in order to define a time invariant function, and then use the techniques of divergence‐free solvable decomposition and symmetric composition to obtain volume‐preserving integrators in the extended phase space. Here, we have developed the technique by constructing multiple extended‐variable formalism in order to enhance the handling in actual simulation, and by constituting higher order integrators to obtain further accuracies. Using these integrators, we perform constant temperature molecular dynamics simulations of liquid water, liquid argon and peptide in liquid water droplet. The temperature control is obtained through an extended version of the Nosé‐Hoover equations. Analyzing the effects of the simulation conditions including time step length, initial values, boundary conditions, and equation parameters, we investigate local accuracy, global accuracy, computational cost, and sensitivity along with the sampling validity. According to the results of these simulations, we show that the volume‐preserving integrators developed by the current method are more effective than traditional integrators that lack the volume‐preserving property. © 2008 Wiley Periodicals, Inc. J Comput Chem, 2009  相似文献   
7.
In this paper we develop, study, and test a Lie group multisymplectic integrator for geometrically exact beams based on the covariant Lagrangian formulation. We exploit the multisymplectic character of the integrator to analyze the energy and momentum map conservations associated to the temporal and spatial discrete evolutions.  相似文献   
8.
供应和需求不确定条件下物流服务供应链能力协调研究   总被引:4,自引:0,他引:4  
为解决物流能力供应和需求不确定环境下,物流服务集成商和供应商能力采购和投资的协调问题,建立了Stackelberg主从博弈下物流服务集成商和供应商的决策模型,提出了基于收益共享的能力采购费用补偿协调机制,给出了实现供应链协同以及帕雷托改进的合约参数设计和取值区间.数值分析进一步验证了该协调机制的有效性,以及供应和需求波动对决策双方行为的影响.研究结果表明,物流服务集成商通过调节合约参数取值能有效协调供应和需求随机环境下物流服务供应链的采购和投资风险.  相似文献   
9.
(Anti)-/ferromagnetic Heisenberg spin models arise from discretization of Landau–Lifshitz models in micromagnetic modelling. In many applications it is essential to study the behavior of the system at a fixed temperature. A formulation for thermostatted spin dynamics was given by Bulgac and Kusnetsov, which incorporates a complicated nonlinear dissipation/driving term while preserving spin length. It is essential to properly model this term in simulation, and simplified schemes give poor numerical performance, e.g., requiring an excessively small timestep for stable integration. In this paper we present an efficient, structure-preserving method for thermostatted spin dynamics.  相似文献   
10.
HNN是一类基于物理先验学习哈密尔顿系统的神经网络.本文通过误差分析解释使用不同积分器作为超参数对HNN的影响.如果我们把网络目标定义为在任意训练集上损失为零的映射,那么传统的积分器无法保证HNN存在网络目标.我们引进反修正方程,并严格证明基于辛格式的HNN具有网络目标,且它与原哈密尔顿量之差依赖于数值格式的精度.数值实验表明,由辛HNN得到的哈密尔顿系统的相流不能精确保持原哈密尔顿量,但保持网络目标;网络目标在训练集、测试集上的损失远小于原哈密尔顿量的损失;在预测问题上辛HNN较非辛HNN具备更强大的泛化能力和更高的精度.因此,辛格式对于HNN是至关重要的.  相似文献   
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