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   737篇
  免费   9篇
  国内免费   5篇
化学   612篇
晶体学   5篇
力学   9篇
数学   39篇
物理学   86篇
  2022年   6篇
  2020年   3篇
  2019年   10篇
  2018年   8篇
  2017年   3篇
  2016年   18篇
  2015年   11篇
  2014年   3篇
  2013年   45篇
  2012年   33篇
  2011年   32篇
  2010年   19篇
  2009年   18篇
  2008年   45篇
  2007年   42篇
  2006年   46篇
  2005年   53篇
  2004年   43篇
  2003年   51篇
  2002年   52篇
  2001年   15篇
  2000年   15篇
  1999年   9篇
  1998年   9篇
  1997年   6篇
  1996年   6篇
  1994年   13篇
  1993年   14篇
  1992年   4篇
  1991年   6篇
  1990年   4篇
  1989年   5篇
  1988年   6篇
  1987年   3篇
  1986年   4篇
  1985年   11篇
  1984年   6篇
  1983年   4篇
  1982年   8篇
  1981年   3篇
  1980年   5篇
  1979年   8篇
  1977年   8篇
  1976年   3篇
  1975年   4篇
  1974年   4篇
  1973年   5篇
  1972年   7篇
  1971年   4篇
  1966年   2篇
排序方式: 共有751条查询结果,搜索用时 15 毫秒
61.
Let a set {Xλλ  Λ} of subspaces of a topological space X be a cover of X. Mathematical conditions are proposed for each subspace Xλ to define a map gXλ:XλX which has the following property specific to the tent map known in the baker’s transformation. Namely, for any infinite sequence ω0ω1ω2, … of Xλ, λ  Λ, we can find an initial point x0  ω0 such that gω0(x0)ω1,gω1(gω0(x0))ω2,…. The conditions are successfully applied to a closed cover of a weak self-similar set.  相似文献   
62.
63.
64.
For a nonnegative integrable weight function on the unit circle , we provide an expression for , in terms of the series coefficients of the outer function of , for the weighted distance , where is the normalized Lebesgue measure and ranges over trigonometric polynomials with frequencies in , , . The problem is open for .

  相似文献   

65.
Waveguide Bragg gratings were fabricated by plasma-enhanced chemical-vapor deposition followed by irradiation with KrF excimer laser light through a phase mask. The period of the Bragg grating was 0.53 mum, and the Bragg wavelength was ~1.53 mum . The temperature dependence of the Bragg wavelength was 11 pm/ degrees C for a 10GeO(2) -90SiO(2)(mol.%) core waveguide on a Si substrate, and the Bragg wavelength shift was successfully reduced to 5.0pm/ degrees C by use of a 14GeO(2)-12B(2)O(3)-74SiO(2) (mol.%) core and a crystallized glass substrate with a thermal-expansion coefficient of -2.0x10(-6)(/ degrees C) .  相似文献   
66.
Remarks on Herz-Type Hardy Spaces   总被引:4,自引:0,他引:4  
Basic properties of the Herz-type Hardy spaces , such as the boundedness of singular integral operators and the fractional integration operators, atomic decomposition, dense subspaces, etc., are established in the full range 0 < q < ∞. Partly supported by the Grants-in-Aid for Scientific Research (A)(1)11304009, (B)(1)10440046, Japan Society for the Promotion of Science.  相似文献   
67.
We investigated the photoluminescence (PL) properties of regularly arranged N‐polar InN microcrystals with m ‐plane sidewall facets. We observed narrow PL emission at 0.678 eV with a linewidth of ~14 meV at 4 K and a clear band‐filling effect with increasing excitation power. We also observed a normal red shift of the PL peak energy as large as 51 meV (~150 nm) with increasing temperature from 4 to 300 K, similar to that observed for non‐degenerated semiconductors. The integrated PL intensity ratio I300K/I4K was measured to be 6.1%. These results indicate that InN microcrystals have a low residual carrier density and excellent optical properties without being adversely affected by surface electron accumulation, despite their relatively high surface area. (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)  相似文献   
68.
The European Physical Journal E - We consider a microscopic field theoretical approach for interacting active nematic particles. With only steric interactions the self-propulsion strength in such...  相似文献   
69.
Based on techniques for single molecule imaging and nanomanipulation by optical tweezers, we have developed a new technique that allows simultaneous measurement of individual ATPase and mechanical reactions from a single myosin molecule during force generation. We show how the ATPase reaction couples to the mechanical reaction directly at the single molecule level. The results show that the myosin head can produce force even after releasing the bound nucleotide, probably ADP, suggesting that the chemical energy driven by ATP hydrolysis can be hysteretically stored in the myosin molecule. This view does not support a widely accepted hypothesis in which the force generation is tightly coupled to ligand dissociation.This paper was originally presented as an invited paper at the seventh Meeting on Near Field Optics, which was held on July 1, 1998 at Nagoya University, Nagoya, organized by the Research Group on Near Field Optics of the Optical Society of Japan, an affiliate of the Japan Society of Applied Physics.  相似文献   
70.
Let be a fractional ARIMA(p,d,q) process with partial autocorrelation function α(·). In this paper, we prove that if d∈(−1/2,0) then |α(n)|∼|d|/n as n→∞. This extends the previous result for the case 0<d<1/2.  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