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991.
Edward Karakhanov Anton Maximov Sergey Kardashev Yulia Kardasheva Anna Zolotukhina Edward Rosenberg Jesse Allen 《Macromolecular Symposia》2011,304(1):55-64
Summary: Nanostructured regular materials based on cross-linked polypropylene imine (PPI) dendrimers and silica-gel polyamine composites were used as a support for the synthesis of Pd nanoparticles. The materials were tested as catalysts and displayed a high activity and selectivity for the hydrogenation of conjugated double bonds. 相似文献
992.
We present a new method of investigating the so-called quasi-linear strongly-damped wave equations
993.
Jesus Ildefonso Díaz Sergey Shmarev 《Journal of Mathematical Analysis and Applications》2009,352(1):475-495
We study the dynamics and regularity of the level sets in solutions of the semilinear parabolic equation
994.
Andrei V. Churakov Elmira Kh. Lermontova Kirill V. Zaitsev Mengmeng Huang Sergey S. Karlov Galina S. Zaitseva Judith A. K. Howard 《Acta Crystallographica. Section C, Structural Chemistry》2009,65(11):o587-o592
Four distinct hydrogen‐bonding topologies were observed in the structures of six diethanolamine ligands. These compounds are (1R*,2R*)‐2‐[(2‐hydroxyethyl)(methyl)amino]‐1,2‐diphenylethanol, C17H21NO2, (I), 1‐[(2S)‐2‐(hydroxydiphenylmethyl)pyrrolidin‐1‐yl]‐2‐methylpropan‐2‐ol, C21H27NO2, (II), 2‐[(2‐hydroxyethyl)(methyl)amino]‐1,1‐diphenylethanol, C17H21NO2, (III), 1‐{(2‐hydroxy‐2‐methylpropyl)[(1S)‐1‐phenylethyl]amino}‐2‐methylpropan‐2‐ol, C16H27NO2, (IV), 1‐{[(2R)‐2‐hydroxy‐2‐phenylethyl][(1S)‐1‐phenylethyl]amino}‐2‐methylpropan‐2‐ol, C20H27NO2, (V), and (1R*,2S*)‐2‐[(2‐hydroxyethyl)(methyl)amino]‐1,2‐diphenylethanol, C17H21NO2, (VI). In each compound, all `active' hydroxy H atoms are engaged in hydrogen bonding, but the N atoms are not involved in intermolecular hydrogen bonding. In the structures of (I), (II) and (IV)–(VI), molecules are linked into chains by intermolecular O—H...O interactions. These chains are organized in such a way as to hide the hydrophilic groups inside, and so the outer surfaces of the chains are hydrophobic. The structure of (VI) contains two distinct non‐equivalent systems of intermolecular O—H...O hydrogen bonds formed by disordered hydroxy H atoms. 相似文献
995.
We prove that Dranishnikov's k-dimensional resolution is a UVn − 1-divider of Chigogidze's k-dimensional resolution ck. This fact implies that preserves Z-sets. A further development of the concept of UVn − 1-dividers permits us to find sufficient conditions for to be homeomorphic to the Nöbeling space νk or the universal pseudoboundary σk. We also obtain some other applications. 相似文献
996.
Maurizio Grasselli Giulio Schimperna Antonio Segatti Sergey Zelik 《Journal of Evolution Equations》2009,9(2):371-404
We study the modified Cahn–Hilliard equation proposed by Galenko et al. in order to account for rapid spinodal decomposition
in certain glasses. This equation contains, as additional term, the second-order time derivative of the (relative) concentration
multiplied by a (small) positive coefficient . Thus, in absence of viscosity effects, we are in presence of a Petrovsky type equation and the solutions do not regularize
in finite time. Many results are known in one spatial dimension. However, even in two spatial dimensions, the problem of finding
a unique solution satisfying given initial and boundary conditions is far from being trivial. A fairly complete analysis of
the 2D case has been recently carried out by Grasselli, Schimperna and Zelik. The 3D case is still rather poorly understood
but for the existence of energy bounded solutions. Taking advantage of this fact, Segatti has investigated the asymptotic
behavior of a generalized dynamical system which can be associated with the equation. Here we take a step further by establishing
the existence and uniqueness of a global weak solution, provided that is small enough. More precisely, we show that there exists such that well-posedness holds if (suitable) norms of the initial data are bounded by a positive function of which goes to + ∞ as tends to 0. This result allows us to construct a semigroup on an appropriate (bounded) phase space and, besides, to prove the existence of a global attractor. Finally, we show a regularity
result for the attractor by using a decomposition method and we discuss the existence of an exponential attractor.
相似文献
997.
Xia X Litvinov S Muhler M 《Langmuir : the ACS journal of surfaces and colloids》2006,22(19):8063-8070
Adsorption on heterogeneous surfaces with three basic energy distribution models (uniform model, exponential model, and normal-like model) is studied. Exact analytical solutions of the adsorption isotherms and the heats of adsorption are derived for the uniform and exponential models, and, with these solutions including a numerical solution for the normal-like model, the behavior of the differential heat of adsorption and the "apparent" standard adsorption entropy concerning the overall surface is described as a function of coverage and temperature. The approximations underlying the isotherms and heats of adsorption in the Temkin, Freundlich, and Langmuir-Freundlich types of adsorption are rationalized. By comparing these empirical formulas to the exact solutions, the level of these approximations is found to be identical, which is similar to the "condensation approximation". Their preconditions are that either the temperature is low enough, or the surface is strongly heterogeneous. Generally, they are suitable for the middle coverage range. The exact solutions provide a method to obtain more information on the heats, entropy, and heterogeneity of the catalyst surface from the calorimetric measurement of the heat of adsorption. 相似文献
998.
Rozhok S Fan Z Nyamjav D Liu C Mirkin CA Holz RC 《Langmuir : the ACS journal of surfaces and colloids》2006,22(26):11251-11254
Construction of biomotors is an exciting area of scientific research that holds great promise for the development of new technologies with broad potential applications in areas such as the energy industry and medicine. Herein, we demonstrate the fabrication of prealigned microarrays of motile Escherichia coli bacterial cells on SiOx substrates. To prepare these arrays, holed surfaces with a gold layer on the bottom of the holes were utilized. The attachment of bacteria to the holes was achieved via nonspecific interactions using poly-l-lysine hydrobromide (PLL). Our data suggest that a single motile bacterial cell can be selectively attached to an individual hole on a surface and bacterial cell binding can be controlled by altering the pH, with the greatest occupancy occurring at pH 7.8. Cells attached to hole arrays remained motile for at least 4 h. These data indicate that holed surface structures provide a promising footprint for the attachment of motile bacterial cells to form high-density site-specific functional bacterial microarrays. 相似文献
999.
Makarov S Litwinski C Ermilov EA Suvorova O Röder B Wöhrle D 《Chemistry (Weinheim an der Bergstrasse, Germany)》2006,12(5):1468-1474
Metal-free mononuclear, dinuclear and trinuclear phthalocyanines were prepared by a mixed cyclotetramerisation of a 1,2,4,5-tetracyanobenzene derivative and 4,5-bis(2,6-dimethylphenoxy)phthalonitrile. For the first time, a pi-electron-conjugated trinuclear phthalocyanine was synthesised with phthalocyanine units connected by common annulated benzene rings. The Q band of the trinuclear compound in solution occurs at lambda = 944 nm whereas those of the dinuclear and mononuclear compounds are at lambda = 853/830 and 701/664 nm, respectively. Fluorescence quantum yields, fluorescence lifetimes and singlet-oxygen quantum yields of the compounds were determined. 相似文献
1000.
Vertical excitation energies and oscillator strengths for several valence and Rydberg electronic states of vinyl, propen-1-yl, propen-2-yl, 1-buten-2-yl, and trans-2-buten-2-yl radicals are calculated using the equation-of-motion coupled cluster methods with single and double substitutions (EOM-CCSD). The ground and the lowest excited state (n <-- pi) equilibrium geometries are calculated using the CCSD(T) and EOM-SF-CCSD methods, respectively, and adiabatic excitation energies for the n <-- pi state are reported. Systematic changes in the geometries, excitation energies, and Rydberg state quantum defects within this group of radicals are discussed. 相似文献