首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   127篇
  免费   3篇
化学   49篇
晶体学   4篇
力学   5篇
数学   29篇
物理学   43篇
  2023年   1篇
  2022年   1篇
  2021年   1篇
  2020年   1篇
  2018年   2篇
  2016年   1篇
  2014年   2篇
  2013年   6篇
  2012年   2篇
  2010年   3篇
  2008年   2篇
  2007年   6篇
  2006年   2篇
  2005年   2篇
  2004年   12篇
  2003年   4篇
  2002年   2篇
  2001年   1篇
  1999年   3篇
  1998年   2篇
  1996年   1篇
  1995年   3篇
  1993年   1篇
  1992年   1篇
  1990年   1篇
  1989年   1篇
  1988年   1篇
  1987年   1篇
  1985年   3篇
  1984年   5篇
  1983年   6篇
  1982年   2篇
  1981年   7篇
  1980年   8篇
  1978年   2篇
  1977年   5篇
  1976年   1篇
  1975年   5篇
  1974年   2篇
  1973年   3篇
  1972年   3篇
  1969年   1篇
  1968年   1篇
  1966年   1篇
  1958年   1篇
  1954年   2篇
  1939年   1篇
  1933年   3篇
  1931年   2篇
排序方式: 共有130条查询结果,搜索用时 15 毫秒
101.
The Lorentz boost is derived from the Evans wave equation of generally covariant unified field theory by constructing the Dirac spinor from the tetrad in the SU(2) representation space of non-Euclidean spacetime. The Dirac equation in its wave formulation is then deduced as a well-defined limit of the Evans wave equation. By factorizing the dAlembertian operator into Dirac matrices, the Dirac equation in its original first differential form is obtained from the Evans wave equation. Finally, the Lorentz boost is deduced from the Dirac equation using geometrical arguments. A self-consistency check of the Evans wave equation is therefore forged by deducing therefrom the Lorentz boost in the appropriate limit. This procedure demonstrates that the Evans wave equation governs the properties of matter and anti-matter in general relativity and unified field theory and leads both to Fermi-Dirac and Bose-Einstein statistics in general relativity.  相似文献   
102.
Book Review     
Summary Myron Kaufman: Principles of Thermodynamics, No. 15 in Undergraduate Chemistry, A Series of Textbooks, Edited by J.J. Lagowski, Marcel Dekker, Inc., New York, Basel, 2002 xiv + 393 pages, ISBN: 0-8247-0692-7, Price: <InlineEquation><EquationSource=tex>85.00  相似文献   
103.
The energy bands of vanadium monosulfide have been calculated by the KKR method in the muffin-tin approximation. The Fermi surface is very complicated, but there are two nearly cylindrical sheets of nearly equal cross-sections centered around Φ and M respectively. We suggest that this Fermi surface feature can support a charge-density-wave (CDW) state in the conduction electron system at low enough temperatures, and the formation of the CDW explains the lattice phase transition in this compound.  相似文献   
104.
A mechanism is proposed for rotation of magnetic assemblies by a torque consisting of the magnetic dipole moment of the assembly and a magnetic field generated from space–time in Einstein–Cartan–Evans (ECE) field theory. It is shown that when the magnetic assembly is stationary, the space–time is described by a Helmholtz wave equation in the tetrad as eigenfunction. This is a balance condition in which the Cartan torsion of the space–time is zero, but in which the tetrad and spin connection are non-zero. This balance may be broken by a driving current density produced by the magnetic assembly. The Helmholtz equation becomes an undamped oscillator equation. At resonance the torque on the magnetic assembly may be amplified sufficiently to cause the whole assembly to rotate, as observed experimentally in a repeatable and reproducible manner.  相似文献   
105.
大尺寸氟化物晶体的生长是基于对晶体炉热交换的实验研究和计算结果 ,在晶体生长过程的不同阶段解决了复杂结构生长容器的边界条件和温场的二维计算任务。我们在这里给出了晶体生长过程中温场设置和转变的具体数据。所有的计算都是根据晶体、熔体 ,容器材料的光学特性与光谱和温度的关系以及它们的热物理值与温度的关系做出的。这些结果包括了迄今有关氟化物晶体生长系统和过程的最精确的数据 ,可用于生长技术工艺的发展以及晶体生长炉和容器的设计。  相似文献   
106.
107.
Calix[4]arenes bearing one or two methylenebisphosphonic acid fragments were prepared via addition of diethylphosphite to the parent calix[4]arene aldehydes. The resulting compounds displayed stronger inhibition of calf intestine alkaline phosphatase than simple methylenebisphosphonic or 4-hydroxyphenyl methylenebisphosphonic acids. The action of these phosphorylated calix[4]arenes is concordant with partial mixed-type inhibition. The inhibition constants Ki and Ki' for the calix[4]arene bis(methylenebisphosphonic) acid in Tris-HCl buffer at pH 9 are 0.38 microM and 2.8 microM respectively. The replacement of the phosphoric acid moieties on the macrocycle with diethylphosphonates results in a sharp decrease of its inhibitory action. Preorganizing phosphonic acid fragments using a calixarene platform therefore provides a promising approach for the design of efficient alkaline phosphatase inhibitors.  相似文献   
108.
We develop 2‐grid schemes for solving nonlinear reaction‐diffusion systems: where p = (p, q) is an unknown vector‐valued function. The schemes use discretizations based on a mixed finite‐element method. The 2‐grid approach yields iterative procedures for solving the nonlinear discrete equations. The idea is to relegate all the Newton‐like iterations to grids much coarser than the final one, with no loss in order of accuracy. The iterative algorithms examined here extend a method developed earlier for single reaction‐diffusion equations. An application to prepattern formation in mathematical biology illustrates the method's effectiveness. © 1999 John Wiley & Sons, Inc. Numer Methods Partial Differential Eq 15: 589–604, 1999  相似文献   
109.
110.
A non-thermal plasma (NTP) is a promising tool against the development of bacterial, viral, and fungal diseases. The recently revealed development of microbial resistance to traditional drugs has increased interest in the use of NTPs. We have studied and compared the physical and microbicidal properties of two types of NTP sources based on a cometary discharge in the point-to-point electrode configuration and a corona discharge in the point-to-ring electrode configuration. The electrical and emission properties of both discharges are reported. The microbicidal effect of NTP sources was tested on three strains of the bacterium Staphylococcus aureus (including the methicillin-resistant strain), the bacterium Pseudomonas aeruginosa, the yeast Candida albicans, and the micromycete Trichophyton interdigitale. In general, the cometary discharge is a less stable source of NTP and mostly forms smaller but more rapidly emerging inhibition zones on agar plates. Due to the point-to-ring electrode configuration, the second type of discharge has higher stability and provides larger affected but often not completely inhibited zones. However, after 60 min of exposure, the NTP sources based on the cometary and point-to-ring discharges showed a similar microbicidal effect for bacteria and an individual effect for microscopic fungi.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号