全文获取类型
收费全文 | 112篇 |
免费 | 3篇 |
专业分类
化学 | 56篇 |
数学 | 18篇 |
物理学 | 41篇 |
出版年
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.
D.F. Sanchez F.P. Luce Z.E. Fabrim M.A. Sortica P.F.P. Fichtner P.L. Grande 《Surface science》2011,605(7-8):654-658
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.
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.
Kuai L Ong SE Madison JM Wang X Duvall JR Lewis TA Luce CJ Conner SD Pearlman DA Wood JL Schreiber SL Carr SA Scolnick EM Haggarty SJ 《Chemistry & biology》2011,18(7):891-906
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.
Roberto Sigfrido Gallegos Olea Luce Maria Brandão Torres Luiz Carlos Roque Nidia Franca Roque 《Magnetic resonance in chemistry : MRC》1994,32(6):378-379
The 13C NMR chemical shifts of the triterpenes glutinol, glutinone and acetylglutinol were measured and analysed. 相似文献