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101.
Boullet J Sabourdy D Desfarges-Berthelemot A Kermène V Pagnoux D Roy P Dussardier B Blanc W 《Optics letters》2005,30(15):1962-1964
Coherent combining is demonstrated in a clad-pumped Yb-doped double-core fiber laser. A slope efficiency of more than 70% is achieved with 96% of the total output power in the fundamental mode of one of the two cores. This high combining efficiency is obtained when both cores are coupled via a biconical fused taper in a Michelson interferometer configuration. 相似文献
102.
The tris(2-fluoro-6-pyridylmethyl)amine ligand, F3TPA, can easily be prepared by reaction of 2-fluoro-6-bromomethylpyridine with NH4Cl in the presence of NaOH. Complexation to FeCl2 affords the high-spin F3TPAFe(II)Cl2 complex, the X-ray structure of which is reported. The three fluorine substituents provide enough steric hindrance to force the tripod to coordinate in the tridentate mode, affording a trigonal bipyramidal iron center. This complex is thermally stable, and it reacts instantaneously with molecular dioxygen to afford the unsymmetrical micro-oxo dimer F3TPAFe(III)ClOFe(III)Cl3 as the major product, together with small amounts of the mixed salt [F3TPAFe(II)Cl]2, [Fe(III)2OCl6]. These two complexes have been isolated and characterized by X-ray diffraction analysis. A mechanism by which they are obtained is suggested and seems to parallel the well-known process of autoxidation of ferrous porphyrins. 相似文献
103.
We consider a threshold autoregressive stochastic volatility model where the driving noises are sequences of iid regularly
random variables. We prove that both the right and the left tails of the marginal distribution of the log-volatility process
(αt)t are regularly varying with tail exponent −α with α > 0. We also determine the exact values of the coefficients in the tail behaviour of the process (αt)t.
AMS 2000 Subject Classification. Primary—62G32, 62PO5 相似文献
104.
A method is proposed to find the digital input signals to enter in nonlinear acoustical systems (power amplifiers, transducers, etc.) in order to obtain desired arbitrary response signals. The searched input signals are found by performing a Monte Carlo search guided by a simulated annealing process applied to a hidden model with a small number of parameters. The physical system is actually used in the optimization procedure, in a real-time manner, so that no theoretical model of the system response is required. The main aspects of the algorithm are described and illustrated with several examples. 相似文献
105.
106.
It is well known that the complexity of the Delaunay
triangulation of $n$ points in $\RR ^d$, i.e., the number of its
simplices, can be $\Omega (n^{\lceil {d}/{2}\rceil })$. In
particular, in $\RR ^3$, the number of tetrahedra can be quadratic.
Put another way, if the points are uniformly distributed in a cube or a
ball, the expected complexity of the Delaunay triangulation is only
linear. The case of points distributed on a surface is of great
practical importance in reverse engineering since most surface
reconstruction algorithms first construct the Delaunay triangulation
of a set of points measured on a surface.
In this paper we bound the complexity of the Delaunay triangulation
of points distributed on the boundary of a given polyhedron. Under a
mild uniform sampling condition, we provide deterministic asymptotic
bounds on the complexity of the three-dimensional Delaunay triangulation of the
points when the sampling density increases. More precisely, we show
that the complexity is $O(n^{1.8})$ for general polyhedral surfaces
and $O(n\sqrt{n})$ for convex polyhedral surfaces.
Our proof uses a geometric result of independent interest that states
that the medial axis of a surface is well approximated by a subset of
the Voronoi vertices of the sample points. 相似文献
107.
108.
Dominique Bourn 《Applied Categorical Structures》2000,8(1-2):81-113
Given a left exact category B, the construction of the nerve functor
n
for n-groupoids in B is related to a certain property of the category S-S i m p l
n – 1
B of the split (n – 1)-truncated simplicial objects in B, which allows us to define the split n-truncated simplicial objects in B completely internally to S-S i m p l
n – 1
B and thus to construct intrisincally from it the category S-S i m p l
n
B. 相似文献
109.
Stocco A Crassous J Salonen A Saint-Jalmes A Langevin D 《Physical chemistry chemical physics : PCCP》2011,13(8):3064-3072
The stabilization of aqueous foams solely by solid particles is an active field of research. Thanks to controlled particle chemistry and production devices, we are able to generate large volumes of such foams. We previously investigated some of their unique properties, especially the strongly reduced coarsening. Here we report another type of study on these foams: performing diffusing wave spectroscopy (DWS), we investigate for the first time the internal dynamics on the scales of both the particles and the bubbles. When compared to surfactant foams, unusual features are observed; in particular, two well-separated modes are found in the dynamics, both evolving with foam aging. We propose an interpretation of these specificities, taking into account both the scattering by free particles in the foam fluid (fast mode), and by the foam structure (slow mode). To validate our interpretation, we show that independent measurements of the interstitial fluid scattering length, obtained indirectly on the foam and directly on the drained liquid, are in good agreement. We have also identified the experimental conditions required to observe such two-process dynamics. Counter-intuitively, the fraction of free particles within the foam interstitial fluid has to be very low to get an optimal signature of these particles on the DWS correlation curves. This study also sheds light on the partitioning of the particles inside the foams and at the interfaces, as the foam ages. Lastly, the results shown here (obtained by analyzing the fluctuations of the transmitted light) implement the previous ones (obtained by analyzing the mean transmitted intensity), and prove that the foam structure is actually not fully frozen. 相似文献
110.
Two tetranuclear manganese(II) complexes [Mn(II)4(thiaS)2] (1) and [Mn(II)4(thiaSO)2] (2) have been synthesized under solvothermal conditions in methanol with p-tert-butylthiacalix[4]arene (thiaS) and p-tert-butylsulfinylthiacalix[4]arene (thiaSO). For both complexes, the structure has been established from single-crystal X-ray diffraction. [Mn4(thiaS)2].H2O (1) crystallizes in the orthorhombic Immm (No. 71) space group with the following parameters: a = 18.213 (5) angstroms, b = 19.037 (5) angstroms, c = 29.159 (5) angstroms, V = 10110 (4) angstroms3, and Z = 4. [Mn4(thiaSO)2].H2O (2) crystallizes in the monoclinic C2/m (No. 12) space group with the following parameters: a = 33.046(1) angstroms, b = 19.5363 (8) angstroms, c = 15.7773 (9) angstroms, beta = 115.176 (2) degrees, V = 9218.3 (8) angstroms3, and Z = 4. The two complexes are neutral and are best described as manganese squares sandwiched between two thiacalixarene macrocycles. In both complexes, each manganese center is six-coordinated in a trigonal prismatic geometry with four phenoxo oxygen atoms plus two sulfur atoms for 1 or two oxygen atoms from SO groups for 2. The two tetranuclear complexes exhibit identical magnetic behaviors resulting from antiferromagnetic interactions between the four manganese centers. The simulation of the magnetic susceptibility was done considering a single exchange-coupling constant between the manganese(II) ions, J (H = -J(S1S2 + S2S3 + S3S4 + S1S4)). The best fits give the same result for the two complexes: g = 1.94 and J = -5.57 cm(-1). 相似文献