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971.
Konstantin Berlin Dianne P. OLeary David Fushman 《Journal of magnetic resonance (San Diego, Calif. : 1997)》2009,201(1):25-33
We describe a new, computationally efficient method for computing the molecular alignment tensor based on the molecular shape. The increase in speed is achieved by re-expressing the problem as one of numerical integration, rather than a simple uniform sampling (as in the PALES method), and by using a convex hull rather than a detailed representation of the surface of a molecule. This method is applicable to bicelles, PEG/hexanol, and other alignment media that can be modeled by steric restrictions introduced by a planar barrier. This method is used to further explore and compare various representations of protein shape by an equivalent ellipsoid. We also examine the accuracy of the alignment tensor and residual dipolar couplings (RDC) prediction using various ab initio methods. We separately quantify the inaccuracy in RDC prediction caused by the inaccuracy in the orientation and in the magnitude of the alignment tensor, concluding that orientation accuracy is much more important in accurate prediction of RDCs. 相似文献
972.
Kalin S. Simeonov Konstantin Yu Amsharov Martin Jansen 《Chemistry (Weinheim an der Bergstrasse, Germany)》2009,15(8):1812-1815
Welcome to the family! The constitution of the chiral D2‐C80 fullerene has been confirmed through single‐crystal X‐ray analysis of the chlorinated C80Cl12. The addition pattern of the chlorine atoms in the structure of C80Cl12 together with other structures of halogenated higher fullerenes is discussed. A stepwise principle of higher fullerene reactivity is proposed. Unusual short intermolecular chlorine–chlorine contacts are reported.
973.
Konstantin Eckle Nicolai Bissantz Holger Dette Katharina Proksch Sabrina Einecke 《Annals of the Institute of Statistical Mathematics》2018,70(3):647-689
In this paper, we propose methods for inference of the geometric features of a multivariate density. Our approach uses multiscale tests for the monotonicity of the density at arbitrary points in arbitrary directions. In particular, a significance test for a mode at a specific point is constructed. Moreover, we develop multiscale methods for identifying regions of monotonicity and a general procedure for detecting the modes of a multivariate density. It is shown that the latter method localizes the modes with an effectively optimal rate. The theoretical results are illustrated by means of a simulation study and a data example. The new method is applied to and motivated by the determination and verification of the position of high-energy sources from X-ray observations by the Swift satellite which is important for a multiwavelength analysis of objects such as Active Galactic Nuclei. 相似文献
974.
Vadym Prysiazhnyi Alonso H. Ricci Castro Konstantin G. Kostov 《Brazilian Journal of Physics》2017,47(1):65-71
Atmospheric pressure plasma jet operated in argon was utilized to modify surfaces of glass, acrylic, and PTFE dielectrics. This paper describes the influence of the dielectric substrate on operation and properties of plasma. Two modes of operation (each of those have two patterns) were described. The transition from one mode to another, values of the dissipated power, and spreading of plasma over the dielectric surfaces strongly depended on the substrate material. Additionally, three methods of plasma spreading estimation were presented and discussed. 相似文献
975.
Selection of surfactants for stable paraffin-in-water dispersions, undergoing solid-liquid transition of the dispersed particles 总被引:1,自引:0,他引:1
Golemanov K Tcholakova S Denkov ND Gurkov T 《Langmuir : the ACS journal of surfaces and colloids》2006,22(8):3560-3569
A new experimental procedure is proposed for express evaluation of the coalescence stability of dispersions, in which the dispersed particles undergo solid-liquid phase transition. The procedure includes centrifugation of the dispersion concurrently with the phase transition of the particles and allows precise quantification of dispersion stability in terms of a critical pressure, at which the coalescence between the dispersed particles/drops takes place. The method is applied for studying the effects of surfactant type and concentration on the stability of paraffin-in-water dispersions, which have potential application in energy storage and transportation systems. Several types of water-soluble surfactants (anionic, nonionic, and polymeric) are compared, whereas hexadecane or tetradecane is used as a dispersed phase. Most of the studied individual surfactants are found to be inefficient stabilizers (except for the nonionic Tween 40 and Tween 60). However, the dispersion stability increases significantly after the addition of appropriate cosurfactants, such as hexadecanol, Brij 52, or cocoamidopropyl betaine. Surfactants and cosurfactants with longer hydrophobic tails are better stabilizers than those with shorter tails. The obtained results are discussed from the viewpoint of the mechanisms of particle/drop coalescence during the solid-liquid-phase transition. The consistency and the undercooling temperatures of the studied dispersions are also discussed, because these properties are important for their practical applications. The proposed procedure for evaluation of dispersion stability and some of the conclusions could be relevant to food emulsions, in which dispersed fat particles undergo solid-liquid-phase transition of similar type. 相似文献
976.
Dilyara R. Chulakova Ambara R. Pradipta Olga A. Lodochnikova Danil R. Kuznetsov Kseniya S. Bulygina Ivan S. Smirnov Konstantin S. Usachev Liliya Z. Latypova Almira R. Kurbangalieva Katsunori Tanaka 《化学:亚洲杂志》2019,14(22):4048-4054
The chiral substituted 1,5‐diazacyclooctane (1,5‐DACO) is of considerable importance and has attracted attention from a wide range of fields due to their unique chemical and biological properties. Despite the application potential, further study has not been optimized due to difficulties in their synthetic accessibility. Here, we report that the 1,5‐DACO bearing a chiral auxiliary obtained from the formal [4+4] cycloaddition of N‐alkyl‐α,β‐unsaturated imines can be further derivatized by nucleophilic alkylation to give various chiral substituted 1,5‐DACO derivatives. The removal of the chiral auxiliary was effectively carried out using hydrogenation over Pearlman's catalyst. This methodology allows the production of a broad range of unprecedented optically active 2,6‐dialkyl‐1,5‐DACO, which could not be accessed by other methods. 相似文献
977.
Konstantin Soldatov Alexey Peretyatko Petr Andriushchenko Konstantin Nefedev Yutaka Okabe 《Physics letters. A》2019,383(12):1229-1234
We study diluted antiferromagnetic Ising models on triangular and kagome lattices in a magnetic field, using the replica-exchange Monte Carlo method. We observe seven and five plateaus in the magnetization curve of the diluted antiferromagnetic Ising model on the triangular and kagome lattices, respectively, when a magnetic field is applied. These observations contrast with the two plateaus observed in the pure model. The origin of multiple plateaus is investigated by considering the spin configuration of triangles in the diluted models. We compare these results with those of a diluted antiferromagnetic Ising model on the three-dimensional pyrochlore lattice in a magnetic field pointing in the [111] direction, sometimes referred to as the “kagome-ice” problem. We discuss the similarity and dissimilarity of the magnetization curves of the “kagome-ice” state and the two-dimensional kagome lattice. 相似文献
978.
979.
Egor I. Zhimulev Anatoly I. Chepurov Valeri M. Sonin Konstantin D. Litasov Aleksei A. Chepurov 《高压研究》2018,38(2):153-164
The present work was aimed to understand the role of light elements for the penetration of Fe melt through the olivine matrix at high P–T parameters. We studied the mechanism of Fe melt percolation through the olivine matrix, whose interstices are filled with carbon and sulfur. The experiments were performed using a ‘split-sphere’ type multi-anvil high pressure apparatus at pressures 2.0 and 5.5?GPa and a temperature of 1600°C. It was demonstrated that the Fe melt penetrated through the olivine matrix at a relatively high rates in the presence of carbon or sulfur in the interstices. The percolation occurs due to fast dissolution of the light elements into Fe melt and filling of these interstices by the melt. 相似文献
980.
Tatiana S. Sokolova Peter I. Dorogokupets Konstantin D. Litasov Boris S. Danilov Anna M. Dymshits 《高压研究》2018,38(3):193-211
Modified equations of state (EoS) of forsterite, wadsleyite, ringwoodite, akimotoite, bridgmanite and post-perovskite based on the Helmholtz free energy are described using Microsoft Excel spreadsheets. The equations of state were set up by joint analysis of reference experimental data and can be used to calculate thermodynamic and thermoelastic parameters and P–V–T properties of the Mg-silicates. We used Visual Basic for Applications module in Microsoft Excel and presented a simultaneous calculation of full set of thermodynamic and thermoelastic functions using only T–P and T–V data as input parameters. Phase transitions in the MgSiO3–MgO system play an important role in the interpretation of the seismic boundaries of the upper Earth’s mantle and in the D″ layer. Therefore, proposed EoSes of silicates in the MgSiO3–MgO system have clear geophysical implications. The developed software will be interesting to specialists who are engaged to study the mantle mineralogy and Earth’s interior. 相似文献