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81.
Time integration of Fourier pseudospectral DNS is usually performed using the classical fourth-order accurate Runge-Kutta method or other second- or third-order methods, with a fixed step size. We investigate the use of higher-order Runge-Kutta pairs and automatic step size control based on local error estimation. We find that the fifth-order accurate Runge-Kutta pair of Bogacki and Shampine gives much greater accuracy at a significantly reduced computational cost. Specifically, we demonstrate speedups of 2× to 10× for the same accuracy. Numerical tests (including the Taylor-Green vortex, Rayleigh-Taylor instability, and homogeneous isotropic turbulence) confirm the reliability and efficiency of the method. We also show that adaptive time stepping provides a significant computational advantage for some problems (like the development of a Rayleigh-Taylor instability) without compromising accuracy. 相似文献
82.
Jan Maier Marian Deutsch Dr. Julia Merz Prof. Dr. Qing Ye Oliver Diamond Maja-Tessa Schilling Dr. Alexandra Friedrich Prof. Dr. Bernd Engels Prof. Dr. Todd B. Marder 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(68):15989-16000
We have investigated the cannibalistic self-trapping reaction of an ortho-benzyne derivative generated from 1,11-bis(p-tolyl)undeca-1,3,8,10-tetrayne in an HDDA reaction. Without adding any specific trapping agent, the highly reactive benzyne is trapped by another bisdiyne molecule in at least three different modes. We have isolated and characterized the resulting products and performed high-level calculations concerning the reaction mechanism. During the cannibalistic self-trapping process, either a C≡C triple bond or an sp–sp3 C−C single bond is cleaved. Up to seven rings and nine C−C bonds are formed starting from two 1,11-bis(p-tolyl)undeca-1,3,8,10-tetrayne molecules. Our experiments and calculations provide considerable insight into the variety of reaction pathways which the ortho-benzyne derivative, generated from a bisdiyne, can take when reacting with another bisdiyne molecule. 相似文献
83.
M. R. Schilling F. Preusser G. Gutnikov 《Journal of Thermal Analysis and Calorimetry》1992,38(7):1635-1643
The product of the reaction between calcium montmorillonite and hexamethylene diisocyanate in acetone, catalyzed with dibutyltin dilaurate, was studied by thermogravimetry to determine the amount of polymer produced. The method developed to determine polymer content in the clay possessed excellent accuracy and precision, and produced more consistent results than traditional gravimetric methods.This research originated as a portion of the author's Master's degree research undertaken at California State Polytechnic University Pomona, and conducted at the Getty Conservation Institute (GCI). The author is indebted to the following colleagues at the GCI for providing advice and direction: Neville Agnew, Charles Selwitz, Dusan Stulik, James Druzik, David Scott and William Ginell. Consolidated adobe samples were prepared at the GCI by Richard Coffman, and by Dr. Michael Geis, department of Chemistry, Loyola University. Much valuable information and technical assistance was provided by Dr. Hans Wiedemann and Genia Paul, both of Mettler Instrument Corporation. 相似文献
84.
85.
From isothermalM(H) curves nearT
c
, measured on polycrystalline Tl2Ba2Ca
n–1Cu
n
O2n
+4 and (Bi, Pb)2Sr2Ca
n–1Cu
n
O2n+4 (n=2,3) samples, we deduce the in-plane penetration depths ab as functions of temperature. An estimate according to the BCS weak-coupling clean-limit fit, which produces the data nearT
c
very well, yields ab(0)=3100 Å, 2320 Å 2210 Å, and 1960 Å for Bi2Sr2CaCu2O8, Bi1.6Pb0.4Sr2Ca2Cu3O10, Tl2Ba2CaCu2O8, and Tl2Ba2Ca2Cu3O10, respectively. A comparison between strong-coupling and weak coupling fitting curves clearly favours the weak-coupling temperature dependence of ab nearT
c
. 相似文献
86.
R. Kotte W. D. Fromm E. Hentschel H. G. Ortlepp K. D. Schilling W. Seidel F. Stary G. Zwicker 《Zeitschrift für Physik A Hadrons and Nuclei》1988,330(2):189-195
Nuclear fission accompanied by long-range alpha particles has been investigated. Fission was induced by irradiating a natural uranium target with 13.5 MeV deuterons. The alpha energy and angular distributions are similar to those observed in spontaneous or thermal neutron induced fission. The correlation angle between alpha particles and light fission fragments has a most probable value of \(\bar \vartheta _{l f - \alpha } = 82.1^\circ \pm 0.9^\circ \) and a dispersion (FWHM) of Δ?=18.4°±1.2°. The mean value and dispersion of the energy distribution are \(\bar {\rm E}_\alpha = 14.8 \pm 1.0 MeV\) and ΔE=9.1±1.2 MeV (FWHM), respectively. The peak-to-valley ratio of the ternary fission fragment mass distribution is found to increase with increasing alpha energy. For near-symmetric mass division, a strong broadening of the angular distribution is observed. The results are discussed in the frame of a multichannel-fission model. 相似文献
87.
88.
Günther Pardatscher Matthaeus Schwarz‐Schilling Dr. Shirley S. Daube Prof. Dr. Roy H. Bar‐Ziv Prof. Dr. Friedrich C. Simmel 《Angewandte Chemie (International ed. in English)》2018,57(17):4783-4786
Lithographic patterning of DNA molecules enables spatial organization of cell‐free genetic circuits under well‐controlled experimental conditions. Here, we present a biocompatible, DNA‐based resist termed “Bephore”, which is based on commercially available components and can be patterned by both photo‐ and electron‐beam lithography. The patterning mechanism is based on cleavage of a chemically modified DNA hairpin by ultraviolet light or electrons, and a subsequent strand‐displacement reaction. All steps are performed in aqueous solution and do not require chemical development of the resist, which makes the lithographic process robust and biocompatible. Bephore is well suited for multistep lithographic processes, enabling the immobilization of different types of DNA molecules with micrometer precision. As an application, we demonstrate compartmentalized, on‐chip gene expression from three sequentially immobilized DNA templates, leading to three spatially resolved protein‐expression gradients. 相似文献
89.