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1.
The stability of Caputo fractional order switching systems is studied in the article by Wu C. etc (Wu and Liu (2019)). The authors claim that the lower bound of the Caputo fractional order derivative needs to be updated at each switching instant. However, the lower bound is relevant to the initial condition and reflects the historical information of a fractional system. No historical information can be changed by subsequent control input as all physical systems are causal systems. The model in Wu and Liu (2019) is physically unattainable and the theoretical achievements cannot be applied in engineering.  相似文献   
2.
This paper presents a new nonlinear reaction–diffusion–convection system coupled with a system of ordinary differential equations that models a combustion front in a multilayer porous medium. The model includes heat transfer between the layers and heat loss to the external environment. A few assumptions are made to simplify the model, such as incompressibility; then, the unknowns are determined to be the temperature and fuel concentration in each layer. When the fuel concentration in each layer is a known function, we prove the existence and uniqueness of a classical solution for the initial and boundary value problem for the corresponding system. The proof uses a new approach for combustion problems in porous media. We construct monotone iterations of upper and lower solutions and prove that these iterations converge to a unique solution for the problem, first locally and then, in time, globally.  相似文献   
3.
闪电回击通道核心中的大电流及其强电磁辐射是引发多种雷电灾害的主要根源。随着现代科技的飞速发展,闪电防护工作显得越为重要。为了完善闪电防护系统,需要从描述闪电回击通道核心的特征参数入手深入研究闪电通道形成和发展过程的微观物理机制。截至目前,光谱观测是获取闪电通道核心特征参数的最佳手段。2015年夏天在青海高原地区的野外试验中,利用由高速摄像机作为记录系统组装的无狭缝光栅摄谱仪,结合快天线地面电场测量仪,记录到一次包括四个回击的云地闪电放电过程的光谱以及与之同步的快电场变化信息。依据光谱,结合等离子体理论计算得到闪电回击通道核心的电导率。在此基础上,应用闪电电动力学模型计算了闪电回击速度、峰值电流、贯穿通道核心的电磁场以及通道核心单位长度的峰值功率等特征参数。结果表明,回击速度在(1.2~2.3)×108 m·s-1的范围内;贯穿回击通道核心的轴向电场、径向电场和磁感应强度的最大值分别在(1.42~1.74)×105 V·m-1,(8.22~9.99)×108 V·m-1和(1.51~2.83) T的范围内。当闪电回击的峰值电流在(7.52~24.05) kA的范围内时,回击通道核心的峰值功率在(0.63~1.92)×109 W·m-1的范围内。另外,分析了电导率、起始电场峰值、回击速度和峰值电流与峰值功率之间的相关性,结果发现峰值电流和峰值功率具有良好的线性关系。研究结果可为探索闪电回击通道形成和发展过程的微观物理机制提供参考依据。  相似文献   
4.
Xi-Lin Bai 《中国物理 B》2022,31(5):53301-053301
As a model molecule of actinide chemistry, UO molecule plays an important role in understanding the electronic structure and chemical bonding of actinide-containing species. We report a study of the laser-induced fluorescence spectra of the U16O and U18O using two-dimensional spectroscopy. Several rotationally resolved excitation spectra were investigated. Accurate molecular rotational constants and equilibrium internuclear distances were reported. Low-lying electronic states information was extracted from high resolution dispersed fluorescence spectra and analyzed by the ligand field theory model. The configuration of the ground state was determined as U2+(5f37s)O2-. The branching ratios, and the vibrational harmonic and anharmonic parameters were also obtained. Radiative lifetimes were determined by recording the time-resolved fluorescence spectroscopy. Transition dipole moments were calculated using the branching ratios and the radiative lifetimes. These findings were elucidated by using quantum-chemical calculations, and the chemical bonding was also analyzed. The findings presented in this work will enrich our understanding of actinide-containing molecules.  相似文献   
5.
具有热活化延迟荧光(thermally activated delayed fluorescence, TADF)特性的配合物可以同时利用单重态和三重态激子,因此发光量子效率较高,近年来受到广大科研工作者的关注。特别是铜金属有机配合物,最低单重态和最低三重态的能量差较小,又可以通过不同配体或取代基进行调节,所以具有较好TADF性能。本文根据配位原子的类型,汇总和分析了近5年具有TADF性质的铜配合物的结构特点和发光性能,并简要讨论了其在有机发光二极管(organic light-emitting diodes,OLEDs)中的潜在应用。  相似文献   
6.
贺艳斌  贾建峰  武海顺 《物理学报》2015,64(20):203101-203101
采用基于色散校正的密度泛函理论进行了第一性原理研究, 详细分析了肼(N2H4)在Ni8Fe8/Ni(111)合金表面稳定吸附构型的吸附稳定性和电子结构及成键性质. 通过比较发现, 肼分子以桥接方式吸附在表面的两个Fe原子上是最稳定的吸附构型, 其吸附能为-1.578 eV/N2H4. 同时发现, 肼分子在这一表面上吸附稳定性的趋势为: 桥位比顶位吸附更有利, 且在Fe原子上比在Ni原子上的吸附作用更强. 进一步分析了不同吸附位点上稳定吸附构型的电子结构、电荷密度转移以及电子局域化情况. 结果发现: 相同吸附位点的电子态密度图基本一致, 并且N原子的p轨道和与之相互作用的表面原子的d轨道之间存在态密度上的重叠; 吸附后电荷密度则主要从肼分子转移到表面原子之上; 在电子局域化函数切面图中也发现吸附后电子被局域到肼分子的N原子和相邻的表面原子之间. 这些电子结构的表征都充分说明肼分子与表面原子之间通过电荷转移形成了强烈的配位共价作用.  相似文献   
7.
8.
利用三体扭曲波计算了3.6 MeV/amu的AuQ+ (Q=24,53)碰撞氦原子单电离的全微分截面,其结果与实验数据和其它理论进行了比较,表明全微分截面受到高电荷入射粒子的强烈影响,敲出的电子被“拖拽”沿着向前的方向. 但是,所有的理论结果都不能呈现实验上全微分截面的独特的向前峰.  相似文献   
9.
The effects of pre-equilibrium emission and secondary decay on the determination of the freeze-out volume are investigated using the isospin-dependent quantum molecular dynamics model accompanied by the statistical decay model GEMINI. Small-mass projectiles and large-mass targets with central collisions are studied at intermediate energies. It is revealed that the proton yields of pre-equilibrium emission are smaller than those of secondary decay. However, the determination of the freeze-out volume from the proton yields is more easily affected by pre-equilibrium emission. Moreover, the percentage of proton yields in the freeze-out stage is found to be approximately 50%.  相似文献   
10.

We propose an entanglement purification protocol (EPP) for purifying separate atoms embedded in single-sided optical cavities. The protocol works in an error-detected pattern, the reflection coefficients only appear as a global coefficient, the success or failure cases are heralded by the detection of photons, these merits make the protocol more robust and practical. We discuss the performance of the protocol with current experimental parameters, the results show the success probability of the present EPP is relatively high. The EPP could provide a promising building block for quantum repeaters and quantum networks in the future.

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