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991.
J. Bekesi J. J. J. Kaakkunen W. Michaeli F. Klaiber M. Schoengart J. Ihlemann P. Simon 《Applied Physics A: Materials Science & Processing》2010,99(4):691-695
A new two-step method, facilitating the rapid generation of super-hydrophobic surface structures via parallel laser processing
followed by a replica generation by injection molding is reported. A self-made fused silica-based diffractive optical element
(DOE) is applied to distribute the laser energy into a 25×25 dot matrix. This DOE is used as a transmission mask for surface
ablation of metal molds, applying short-pulse UV laser pulses. In a subsequent process step, replicas of the processed stamp
are produced by variothermal injection molding, enabling the mass production of the surface pattern on plastics parts. The
resulting topography facilitates a super-hydrophobic behavior of the fabricated components. 相似文献
992.
Simon Dagois-Bohy Sandrine Ngo Sylvain Courrech du Pont Stéphane Douady 《Ultrasonics》2010,50(2):127-132
Some desert sand dunes have the peculiar ability to emit a loud sound up to 110 dB, with a well-defined frequency: this phenomenon, known since early travelers (Darwin, Marco Polo, etc.), has been called the song of dunes. But only in late 19th century scientific observations were made, showing three important characteristics of singing dunes: first, not all dunes sing, but all the singing dunes are composed of dry and well-sorted sand; second, this sound occurs spontaneously during avalanches on a slip face; third this is not the only way to produce sound with this sand.More recent field observations have shown that during avalanches, the sound frequency does not depend on the dune size or shape, but on the grain diameter only, and scales as the square root of g/d - with g the gravity and d the diameter of the grains - explaining why all the singing dunes in the same vicinity sing at the same frequency.We have been able to reproduce these singing avalanches in laboratory on a hard plate, which made possible to study them more accurately than on the field. Signals of accelerometers at the flowing surface of the avalanche are compared to signals of microphones placed above, and it evidences a very strong vibration of the flowing layer at the same frequency as on the field, responsible for the emission of sound.Moreover, other characteristics of the booming dunes are reproduced and analyzed, such as a threshold under which no sound is produced, or beats in the sound that appears when the flow is too large. Finally, the size of the coherence zones emitting sound has been measured and discussed. 相似文献
993.
We study the behavior of Airy beams propagating from a nonlinear medium to a linear medium. We show that an Airy beam initially driven by a self-defocusing nonlinearity experiences anomalous diffraction and can maintain its shape in subsequent propagation, but its intensity pattern and acceleration cannot persist when driven by a self-focusing nonlinearity. The unusual behavior of Airy beams is examined from their energy flow as well as the Brillouin zone spectrum of self-induced chirped photonic lattices. 相似文献
994.
Simon Thomas 《Israel Journal of Mathematics》2018,225(1):321-342
It is shown that for the conjugation action of the symmetric group Sn, when n = 6 or n ≥ 8, all S n -irreducibles appear as constituents of a single conjugacy class, namely, one indexed by a partition λ of n with at least two parts, whose parts are all distinct and taken from the set of odd primes and 1. A simple characterisation of conjugacy classes containing all irreducibles is proved. 相似文献
995.
A careful look at rough path topology applied to Brownian motion reveals new possible properties of the well-known Lévy area, in particular the presence of an intrinsic drift of this area. Using renormalization limit of Markov chains on periodic graphs, we present a construction of such a non-trivial drift and give an explicit formula for it. Several examples with explicit computations are included. 相似文献
996.
Simon Müller 《代数通讯》2018,46(11):4978-4984
A quasi-order on a set S is a binary, reflexive and transitive relation on S. In [3], Fakhruddin introduced the notion of (totally) quasi-ordered fields and showed that each such field is either an ordered field or else a valued field. Hence, quasi-ordered fields are very well suited to treat ordered and valued fields simultaneously. The aim of the present paper is to prove that an analogous dichotomy holds for commutative rings with 1 as well. 相似文献
997.
The aim of this note is to analyze the class \(St[a,b]\) of all real functions on \([a,b]\) with primitive with respect to its size and its relations to other function classes. Apart from recalling previously known results and discussing new results we put a particular emphasis on examples and counterexamples. 相似文献
998.
Kathy Schmidtke Simon H. Stelzig Christian Geidel Markus Klapper Klaus Müllen 《Macromolecular Symposia》2010,296(1):28-37
Two synthetic approaches to modify the surface of inorganic particles are presented. In the first approach the inorganic particles are prepared in-situ in a confined space in inverse emulsions. The used amphiphilic statistical copolymers act not only as emulsifiers, but they also hydrophobize the remaining inorganic particles after the precipitation. This approach represents a versatile method to obtain various inorganic nanoparticles as well as more complex inorganic materials like core-multiple shell and perovskite-based nanoparticles. The second procedure uses preformed inorganic particles, as an aqueous dispersion, to modify them with surface active amphiphilic copolymers in a multicomponent solvent system. This method turns out to be a simple but highly efficient method to modify preformed inorganic nanoparticles. The particles are characterized by SEM, TEM and dynamic light scattering. The modified inorganic nanoparticles are suitable to be homogenously incorporated into a polymer matrix to form transparent nanocomposite materials. 相似文献
999.
Wilfried Imrich Iztok Peterin Simon Špacapan Cun‐Quan Zhang 《Journal of Graph Theory》2010,64(4):267-276
We prove that the strong product G1? G2 of G1 and G2 is ?3‐flow contractible if and only if G1? G2 is not T? K2, where T is a tree (we call T? K2 a K4‐tree). It follows that G1? G2 admits an NZ 3 ‐flow unless G1? G2 is a K4 ‐tree. We also give a constructive proof that yields a polynomial algorithm whose output is an NZ 3‐flow if G1? G2 is not a K4 ‐tree, and an NZ 4‐flow otherwise. © 2009 Wiley Periodicals, Inc. J Graph Theory 64: 267–276, 2010 相似文献
1000.
The solvent around protein molecules in solutions is structured and this structuring introduces a repulsion in the intermolecular interaction potential at intermediate separations. We use Monte Carlo simulations with isotropic, pair-additive systems interacting with such potentials. We test if the liquid-liquid and liquid-solid phase lines in model protein solutions can be predicted from universal curves and a pair of experimentally determined parameters, as done for atomic and colloid materials using several laws of corresponding states. As predictors, we test three properties at the critical point for liquid-liquid separation: temperature, as in the original van der Waals law, the second virial coefficient, and a modified second virial coefficient, all paired with the critical volume fraction. We find that the van der Waals law is best obeyed and appears more general than its original formulation: A single universal curve describes all tested nonconformal isotropic pair-additive systems. Published experimental data for the liquid-liquid equilibrium for several proteins at various conditions follow a single van der Waals curve. For the solid-liquid equilibrium, we find that no single system property serves as its predictor. We go beyond corresponding-states correlations and put forth semiempirical laws, which allow prediction of the critical temperature and volume fraction solely based on the range of attraction of the intermolecular interaction potential. 相似文献