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   112篇
  免费   3篇
化学   56篇
数学   18篇
物理学   41篇
  2022年   1篇
  2021年   2篇
  2016年   2篇
  2015年   3篇
  2014年   2篇
  2013年   8篇
  2012年   9篇
  2011年   7篇
  2010年   1篇
  2009年   4篇
  2008年   2篇
  2007年   2篇
  2005年   9篇
  2004年   6篇
  2003年   5篇
  2002年   5篇
  2001年   3篇
  2000年   6篇
  1999年   2篇
  1998年   2篇
  1997年   1篇
  1996年   1篇
  1995年   4篇
  1994年   4篇
  1993年   2篇
  1992年   3篇
  1991年   1篇
  1990年   2篇
  1988年   1篇
  1987年   1篇
  1985年   1篇
  1984年   1篇
  1983年   1篇
  1982年   1篇
  1981年   1篇
  1976年   2篇
  1975年   1篇
  1974年   3篇
  1973年   1篇
  1932年   2篇
排序方式: 共有115条查询结果,搜索用时 15 毫秒
11.
Suppose that two classes of utility representations of preferences, one additive and one increasing increments, hold simultaneously over uncertain binary alternatives (gambles). This assumption leads to the functional equation $$ f[h(x-y)+y]=f[h(x)]-f[h(y)]+f(y)\qquad (\kappa >x\geq y\geq 0), $$ and to the inequality h(z) ≤ z (z ∈ [0, κ[), where the functions ? and h are strictly increasing maps of the real interval [0, κ[ onto the real intervals [0, λ[ and [0, μ[, respectively, κ, λ, μ ∈]0, ∞]. We present all solutions under the additional assumption of (first-order) differentiability.  相似文献   
12.
Medium energy ion scattering (MEIS) measurements and transmission electron microscopy (TEM) observations are applied to characterize a buried Pb nanoparticle (NP) system synthesized by ion implantation. The NPs are located at the SiO2/Si film interface, forming a dense two-dimensional array. Full 2D (energy and angle) experimental MEIS spectra are compared with Monte Carlo simulated ones. The results demonstrate that MEIS measurements provide microstructural information (mean NP volume of about 150 nm3 and areal density of about 4 × 1011 NP/cm2), but no accurate information on the NP geometrical shape.  相似文献   
13.
Vidal S  Luce J  Penninckx D 《Optics letters》2011,36(17):3494-3496
We report on an experimental demonstration of linear precompensation of nonlinear phase and amplitude transfer functions. We show the effective compensation with a linear all-fiber system of phase-to-amplitude modulation conversion due to a complete frequency conversion system including plane gratings and a nonlinear crystal.  相似文献   
14.
We report on what we believe is the first experimental demonstration of the linear precompensation of a nonlinear transfer function due to frequency conversion. As a proof of principle, we show the effective precompensation with an interferometric filter of FM-to-AM conversion due to second-harmonic generation in a potassium titanyl phosphate crystal.  相似文献   
15.
Target identification remains challenging for the field of chemical biology. We describe an integrative chemical genomic and proteomic approach combining the use of differentially active analogs of small molecule probes with stable isotope labeling by amino acids in cell culture-mediated affinity enrichment, followed by subsequent testing of candidate targets using RNA interference-mediated gene silencing. We applied this approach to characterizing the natural product K252a and its ability to potentiate neuregulin-1 (Nrg1)/ErbB4 (v-erb-a erythroblastic leukemia viral oncogene homolog 4)-dependent neurotrophic factor signaling and neuritogenesis. We show that AAK1 (adaptor-associated kinase 1) is a relevant target of K252a, and that the loss of?AAK1?alters ErbB4 trafficking and expression levels,?providing evidence for a previously unrecognized role for AAK1 in Nrg1-mediated neurotrophic?factor signaling. Similar strategies should lead to the discovery of novel targets for therapeutic development.  相似文献   
16.
17.
We present a theory for the electron-temperature dependence T el of optical second harmonic generation (SHG). Such an analysis is required to study the dynamics of metallic systems with many hot electrons not at equilibrium with the lattice. Using a tight-binding theory for the nonlinear susceptibility χ (2)(ω,T e1) and the Fresnel coefficients we present results for the SHG intensity I (2)(ω,T e1) and its dependence on T el for Cu. Note, χ (2)(ω,T e1) rather than the Fresnel coefficients determines essentially this temperature dependence. Most interestingly we find frequency ranges where I (2)(ω,T e1) increases for small light intensities, while it decreases for large light intensities. Our theory yields also that SHG probes effects due to hot electrons more sensitively than linear optics. The results of our calculations are compared with recent experiments on Cu and Au.  相似文献   
18.
In an exactly solvable model of separable potentials a two channel scattering problem is solved in l = 0 state. The location and the width of a resonance are then defined in three different ways and the resonance parameters so extracted are then compared. This problem is of interest vis-a-vis the Δ(3, 3) resonance parameters.  相似文献   
19.
Acoustic measurements were conducted to determine the degree to which vowel duration, closure duration, and their ratio distinguish voicing of word-final stop consonants across variations in sentential and phonetic environments. Subjects read CVC test words containing three different vowels and ending in stops of three different places of articulation. The test words were produced either in nonphrase-final or phrase-final position and in several local phonetic environments within each of these sentence positions. Our measurements revealed that vowel duration most consistently distinguished voicing categories for the test words. Closure duration failed to consistently distinguish voicing categories across the contextual variables manipulated, as did the ratio of closure and vowel duration. Our results suggest that vowel duration is the most reliable correlate of voicing for word-final stops in connected speech.  相似文献   
20.
The 13C NMR chemical shifts of the triterpenes glutinol, glutinone and acetylglutinol were measured and analysed.  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