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71.
C. R. Gould R. Bass J. v. Czarnecki V. Hartmann K. Stelzer R. Zitzmann Y. Eyal 《Zeitschrift für Physik A Hadrons and Nuclei》1978,284(3):353-354
The multiplicities of neutrons emitted from the light and heavy fragments, respectively, in the inelastic scattering of 7.5 MeV/amu132 Xe ions from197Au have been studied as a function of total energy loss. The measured multiplicity ratios are close to the Au-Xe mass ratio for all Q-values, consistent with a rapid thermalization of the excitation energy. The absolute multiplicity values are lower than expected and suggest significant pre-equilibrium effects. 相似文献
72.
J. Eyal Md A. Mabud K. L. Fischbein J. F. Walter L. S. Osborne Z. Landa 《Applied biochemistry and biotechnology》1994,44(1):65-80
A new strain of the fungusBeauveria bassiana Nov. EO-1 (ATCC 74037), which produces a red pigment in solid and liquid culture, has been isolated from an infected whitefly. The red pigment was extracted and has been identified by mass spectrometry as oosporein, a potent dibenzoquinone mycotoxin. In order to assess the potential of this entomogenous fungi for microbial control purposes, a mycelium bead formulation was developed as a source for pathogenic conidial spores and oosporein production. The mycelium bead preparation was found to be a stable fungal carrier. Conidiation and germination studies have revealed the mycelium bead viability is 100% over a 1-yr period when stored at 4°C. Conidial spore production from the mycelium beads has been falling substantially per time from an initial value of 1.5 × 108 spores per bead to 3 × 105 spores per bead after a year storage at 4°C. However, the mycelium bead formulation continues to produce oosporein on agar media, at the same intensity throughout the 1 yr period. In in vitro and in vivo small scale greenhouse experimentsBeauveria bassiana Nov. EO-1 were compared with known entomogenous fungi,Beauveria sp. andPaceilomyces sp. Beauveria bassiana Nov. EO-1 was found to have a high pathogenicity against foliage insect pests (e.g., whiteflies and mealy bugs), and against soil insects (e.g., citrus root weevils). The utilization of a mycelium bead based on this strain,Beauveria bassiana Nov. EO-1, as a source of conidial spores and oosporein may have broad applications for the control of various insect pests. 相似文献
73.
We show that on every Ramanujan graph \({G}\), the simple random walk exhibits cutoff: when \({G}\) has \({n}\) vertices and degree \({d}\), the total-variation distance of the walk from the uniform distribution at time \({t=\frac{d}{d-2} \log_{d-1} n + s\sqrt{\log n}}\) is asymptotically \({{\mathbb{P}}(Z > c \, s)}\) where \({Z}\) is a standard normal variable and \({c=c(d)}\) is an explicit constant. Furthermore, for all \({1 \leq p \leq \infty}\), \({d}\)-regular Ramanujan graphs minimize the asymptotic \({L^p}\)-mixing time for SRW among all \({d}\)-regular graphs. Our proof also shows that, for every vertex \({x}\) in \({G}\) as above, its distance from \({n-o(n)}\) of the vertices is asymptotically \({\log_{d-1} n}\). 相似文献
74.
Patrick Martin Gleb Vasilyev Guang Chu Mor Boas Arkadii Arinstein Eyal Zussman 《Journal of Polymer Science.Polymer Physics》2019,57(22):1527-1536
The behavior of a mixture of negatively charged cellulose nanocrystals (CNCs) and positively charged poly(allylamine) (PAAm) is examined in aqueous media. By modulating the pH, the acting Coulomb forces can be varied that can lead not only to adsorption of PAAm chains on the CNC surface but also to the development of a supermolecular structure by bridging of CNC rods by extended PAAm chains. This bridging can result in the formation of CNC clusters, which was demonstrated experimentally. Light scattering and rheological studies showed that these clusters begin to grow and merge, ultimately forming a global percolated network above a critical degree of PAAm ionization. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2019 , 57, 1527–1536 相似文献
75.
Nonlinear elastic effects play an important role in the dynamics of microelectromechanical systems (MEMS). A Duffing oscillator
is widely used as an archetypical model of mechanical resonators with nonlinear elastic behavior. In contrast, nonlinear dissipation
effects in micromechanical oscillators are often overlooked. In this work, we consider a doubly clamped micromechanical beam
oscillator, which exhibits nonlinearity in both elastic and dissipative properties. The dynamics of the oscillator is measured
in both frequency and time domains and compared to theoretical predictions based on a Duffing-like model with nonlinear dissipation.
We especially focus on the behavior of the system near bifurcation points. The results show that nonlinear dissipation can
have a significant impact on the dynamics of micromechanical systems. To account for the results, we have developed a continuous
model of a geometrically nonlinear beam-string with a linear Voigt–Kelvin viscoelastic constitutive law, which shows a relation
between linear and nonlinear damping. However, the experimental results suggest that this model alone cannot fully account
for all the experimentally observed nonlinear dissipation, and that additional nonlinear dissipative processes exist in our
devices. 相似文献
76.
Yuwei Hu Fuan Wang Chun‐Hua Lu Julia Girsh Eyal Golub Prof. Itamar Willner 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(49):16203-16209
Mimicking cellular transformations and signal transduction pathways by means of biocatalytic cascades proceeding in organized media is a scientific challenge. We describe two DNA machines that enable the “ON/OFF” switchable activation and deactivation of three‐component biocatalytic cascades. One system consists of a reconfigurable DNA tweezers‐type structure, whereas in the second system the catalytic cascade proceeds on a switchable DNA clamp scaffold. The three‐component catalytic cascades consist of β‐galactosidase (β‐Gal), glucose oxidase (GOx), and the K+‐ion‐stabilized hemin‐G‐quadruplex horseradish peroxidase (HRP)‐mimicking DNAzyme. The hemin‐G‐quadruplex‐bridged closed structure of the tweezers or clamp allows the biocatalytic cascades to operate (switched “ON′′), whereas separation of the hemin‐G‐quadruplex by means of 18‐crown‐6‐ether opens the tweezers/clamp structures, thus blocking the catalytic cascade (switched ”OFF“). This study is complemented by two‐component, switchable biocatalytic cascades composed of GOx and hemin‐G‐quadruplex assembled on hairpin‐bridged DNA tweezers or clamp nanostructures. 相似文献
77.
Let G=(I
n
,E) be the graph of the n-dimensional cube. Namely, I
n
={0,1}
n
and [x,y]∈E whenever ||x−y||1=1. For A⊆I
n
and x∈A define h
A
(x) =#{y∈I
n
A|[x,y]∈E}, i.e., the number of vertices adjacent to x outside of A. Talagrand, following Margulis, proves that for every set A⊆I
n
of size 2
n−1
we have for a universal constant K independent of n. We prove a related lower bound for graphs: Let G=(V,E) be a graph with . Then , where d(x) is the degree of x. Equality occurs for the clique on k vertices.
Received: January 7, 2000
RID="*"
ID="*" Supported in part by BSF and by the Israeli academy of sciences 相似文献
78.
Cerium(IV) ammonium nitrate (CAN)-catalyzed oxidation of alkyl aromatics with potassium bromate affords aldehydes, ketones acids or alcohols in high yields. 相似文献
79.
The degenerate crossing number ${\text{ cr}^{*}}(G)$ of a graph $G$ is the minimum number of crossing points of edges in any drawing of $G$ as a simple topological graph in the plane. This notion was introduced by Pach and Tóth who showed that for a graph $G$ with $n$ vertices and $e \ge 4n$ edges ${\text{ cr}^{*}}(G)=\Omega \big (e^4 / n^4\big )$ . In this paper we completely resolve the main open question about degenerate crossing numbers and show that ${\text{ cr}^{*}}(G)=\Omega \big (e^3 / n^2 \big )$ , provided that $e \ge 4n$ . This bound is best possible (apart for the multiplicative constant) as it matches the tight lower bound for the standard crossing number of a graph. 相似文献
80.
Itai Benjamini Simi Haber Michael Krivelevich Eyal Lubetzky 《Random Structures and Algorithms》2008,32(1):101-114
The isoperimetric constant of a graph G on n vertices, i(G), is the minimum of , taken over all nonempty subsets S ⊂ V (G) of size at most n/2, where ∂S denotes the set of edges with precisely one end in S. A random graph process on n vertices, , is a sequence of graphs, where is the edgeless graph on n vertices, and is the result of adding an edge to , uniformly distributed over all the missing edges. The authors show that in almost every graph process equals the minimal degree of as long as the minimal degree is o(log n). Furthermore, it is shown that this result is essentially best possible, by demonstrating that along the period in which the minimum degree is typically Θ(log n), the ratio between the isoperimetric constant and the minimum degree falls from 1 to , its final value. © 2007 Wiley Periodicals, Inc. Random Struct. Alg., 2008 相似文献