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991.
Abdul Niaz Jan Fischer Jiří Barek Bogdan Yosypchuk Sirajuddin Muhammad Iqbal Bhanger 《Electroanalysis》2009,21(15):1719-1722
An efficient voltammetric method was developed for the determination of maleic acid at a silver amalgam paste electrode (AgA‐PE) in Britton–Robinson buffer pH 2.0. The experimental parameters, such as pH of Britton–Robinson buffer, type of the supporting electrolyte and activation of the electrode surface were optimized. Under the optimal conditions, a linear response was observed over the 2×10?6–1×10?4 mol L?1 maleic acid concentration range, determination limit being 5×10?7 mol L?1. A highly stable response, with a relative standard deviation (RSD) of 1.6% for 45 repetitive measurements of 1×10?4 mol L?1 maleic acid showed that there was no apparent surface passivation indicating the suitability of the method. The method was successfully applied for direct determination of maleic acid in drinking and river water. 相似文献
992.
Lucile Fischer Marion Decossas Dr. Jean‐Paul Briand Dr. Claude Didierjean Dr. Gilles Guichard Dr. 《Angewandte Chemie (International ed. in English)》2009,48(9):1625-1628
The perfect blend : A new class of self‐assembling cyclooligomers with mixed urea/amide backbone is described (see figure). A high level of hierarchical and directional control is achieved: depending on the level of backbone preorganization, columnar or tubular arrangements with either parallel or antiparallel growing modes can be selected.
993.
Osama Shekhah Dr. Hui Wang Denise Zacher Roland A. Fischer Prof. Christof Wöll Prof. 《Angewandte Chemie (International ed. in English)》2009,48(27):5038-5041
One step at a time : The in situ monitoring of the step‐by‐step formation of metal–organic frameworks (MOFs) by using surface plasmon resonance (SPR), allows the nucleation process and the formation of the secondary building units to be investigated. Growth rates on functionalized organic surfaces with different crystallographic orientations can also be studied.
994.
995.
Bhim Bali Prasad Khushaboo Tiwari Meenakshi Singh Piyush S. Sharma Amit K. Patel Shrinkhala Srivastava 《Journal of separation science》2009,32(7):1096-1105
The proposed L ‐histidine sensing system composed of a molecularly imprinted solid‐phase microextraction component combined with a molecularly imprinted polymer sensor was used to determine critical levels of test analyte in a complex matrix of highly diluted human blood serum without any non‐specific sorption and false‐positive contributions. The molecularly imprinted polymer was a zwitterionic polymer brush derived from the disodium salt of EDTA and chloranil, grafted to solid‐phase microextraction material. The hyphenated approach was able to detect L ‐histidine quantitatively with a limit of detection as low as 0.0435 ng/mL (RSD = 0.2%, S/N = 3). 相似文献
996.
Andreas Fischer 《Annals of Pure and Applied Logic》2009,157(2-3):130-138
We study the Hardy field associated with an o-minimal expansion of the real numbers. If the set of analytic germs is dense in the Hardy field, then we can definably analytically separate sets in , and we can definably analytically approximate definable continuous unary functions. A similar statement holds for definable smooth functions. 相似文献
997.
A nonlinear (energy) stability analysis is performed for a rotating magnetized ferrofluid layer heated from below saturating
a porous medium, in the stress-free boundary case. By introducing a generalized energy functional, a rigorous nonlinear stability
result for a thermoconvective rotating magnetized ferrofluid is derived. The mathematical emphasis is on how to control the
nonlinear terms caused by magnetic body force. It is found that the nonlinear critical stability magnetic thermal Rayleigh
number does not coincide with that of linear instability analysis, and thus indicates that the subcritical instabilities are
possible. However, it is noted that, in case of non-ferrofluid, global nonlinear stability Rayleigh number is exactly the
same as that for linear instability. For lower values of magnetic parameters, this coincidence is immediately lost. The effect
of magnetic parameter, M
3, medium permeability, D
a
, and rotation, , on subcritical instability region has also been analyzed. It is shown that with the increase of magnetic parameter, M
3, and Darcy number, D
a
, the subcritical instability region between the two theories decreases quickly while with the increase of Taylor number,
, the subcritical region expands. We also demonstrate coupling between the buoyancy and magnetic forces in the presence of
rotation in nonlinear energy stability analysis as well as in linear instability analysis.
相似文献
998.
In this paper we study properties of numerical solutions of Burger’s equation. Burgers’ equation is reduced to the heat equation on which we apply the Douglas finite difference scheme. The method is shown to be unconditionally stable, fourth order accurate in space and second order accurate in time. Two test problems are used to validate the algorithm. Numerical solutions for various values of viscosity are calculated and it is concluded that the proposed method performs well. 相似文献
999.
Robin J. Chapman Amit Khetan Robert J. Waters 《Journal of Combinatorial Theory, Series A》2009,116(1):205-214
There is a strikingly simple classical formula for the number of lattice paths avoiding the line x=ky when k is a positive integer. We show that the natural generalization of this simple formula continues to hold when the line x=ky is replaced by certain periodic staircase boundaries—but only under special conditions. The simple formula fails in general, and it remains an open question to what extent our results can be further generalized. 相似文献
1000.
Particle methods are a powerful tool to model dynamic systems. Thereby, the system is discretized by a large number of particles, which are interacting via local, predefined particle-particle interaction laws. The resulting computational effort includes neighborhood search, computation of interaction forces and state update via time integration. Particle methods are used in a lot of different fields of applications like computer science, physics and engineering sciences. As the analyzed systems' number of particles constantly grow, performance enhancement has become an important part of present algorithm development. Besides the well-established approach of algorithm parallelization on multi-core CPUs or CPU clusters, modern graphics processing units (GPUs) present a different and trend-setting possibility for massive parallelization even on desktop computers. Among the top four supercomputers of the world, three are already using NVIDIA GPUs. In late 2006, NVIDIA introduced the first GPUs optimized for general purpose calculations. This was followed by the introduction of a new computing architecture differing from the standard graphics user-interface like OpenGL. This architecture is called Compute Unified Device Architecture (CUDA). It enables the user to program the GPU using standard C commands with few additional runtime functions. The differences in architecture between CPU and GPU result in a completely different algorithm implementation. So, a performance evaluation of different types of particle systems implemented on a GPU using CUDA and on a standard CPU is presented. (© 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献