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131.
One-Dimensional Consolidation of Layered and Visco-Elastic Soils under Arbitrary Loading 总被引:1,自引:0,他引:1
IntroductionAfterTerzaghi,alotofscholarshavedoneoutstandingresearchontheproblemsofone_dimensionalconsolidation .Wilson ( 1974) [1] andBaligh( 1978) [2 ] etal.havestudiedtheconsolidationundertherectangularloading .In 1988,WUetal.[3] workedoutthegeneralsolutionsofone_dimen… 相似文献
132.
The two‐phase flow of a flocculated suspension in a closed settling vessel with inclined walls is investigated within a consistent extension of the kinematic wave theory to sedimentation processes with compression. Wall boundary conditions are used to spatially derive one‐dimensional field equations for planar flows and flows which are symmetric with respect to the vertical axis. We analyse the special cases of a conical vessel and a roof‐shaped vessel. The case of a small initial time and a large time for the final consolidation state leads to explicit expressions for the flow fields, which constitute an important test of the theory. The resulting initial‐boundary value problems are well posed and can be solved numerically by a simple adaptation of one of the newly developed numerical schemes for strongly degenerate convection‐diffusion problems. However, from a physical point of view, both the analytical and numerical results reveal a deficiency of the general field equations. In particular, the strongly reduced form of the linear momentum balance turns out to be an oversimplification. Included in our discussion as a special case are the Kynch theory and the well‐known analyses of sedimentation in vessels with inclined walls within the framework of kinematic waves, which exhibit the same shortcomings. In order to formulate consistent boundary conditions for both phases in a closed vessel and in order to predict boundary layers in the presence of inclined walls, viscosity terms should be taken into account. Copyright © 2001 John Wiley & Sons, Ltd. 相似文献
133.
134.
We consider the assignment of enterprise applications in virtual machines to physical servers, also known as server consolidation problem. Data center operators try to minimize the number of servers, but at the same time provide sufficient computing resources at each point in time. While historical workload data would allow for accurate workload forecasting and optimal allocation of enterprise applications to servers, the volume of data and the large number of resulting capacity constraints in a mathematical problem formulation renders this task impossible for any but small instances. We use singular value decomposition (SVD) to extract significant features from a large constraint matrix and provide a new geometric interpretation of these features, which allows for allocating large sets of applications efficiently to physical servers with this new formulation. While SVD is typically applied for purposes such as time series decomposition, noise filtering, or clustering, in this paper features are used to transform the original allocation problem into a low-dimensional integer program with only the extracted features in a much smaller constraint matrix. We evaluate the approach using workload data from a large data center and show that it leads to high solution quality, but at the same time allows for solving considerably larger problem instances than what would be possible without data reduction and model transform. The overall approach could also be applied to similar packing problems in service operations management. 相似文献
135.
In this paper, a new bio-cleaning procedure based on the glucose oxidase (GOx) has been applied on the travertine and peperino substrata to remove the biological patina (i.e., biofilm). Glucose oxidase, used as a model enzyme system, is able to produce in situ H2O2 (the cleaning agent having oxidizing properties) by the enzymatic reaction at room temperature. The travertine and peperino samples came from the Villa Torlonia in Rome (Italy), and an analytical diagnosis on them was performed applying several analytical techniques, such as the differential interference contrast microscopy (DIC), the optical microscope (OM), the Fourier transform infrared spectroscopy (FT-IR) and the X-ray fluorescence (XRF) that evidence the presence of biofilms on the substrata. Better results were obtained on the travertine samples in terms of the cleaning efficiency and the absence of the etching effect on the surface, eventually induced by the peroxide molecule. These results could be explained in terms of the different porosities of the two kinds of stone materials, according to the BET data. A comparative study was also performed to validate the new bio-cleaning procedure, using both traditional approaches based on saturated (NH4)2CO3 solution and EDTA in buffer solution and the enzyme lipase treatments. Among all, the cleaning procedure via GOx shows the best result, probably because the enzyme controls the concentration of the H2O2 in situ and also retains the H2O2 preferentially on the surface (where the biological patina is present) depending on the porosity of the substrata. A synergistic effect, with other enzymes such as lipase and protease, combined with the biocompatibility of the enzymatic treatments, could represent a new way for a higher cleaning efficiency to apply on different stone substrata. 相似文献
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137.
This paper presents an analytical layer-element solution to non-axisymmetric consolidation of multilayered poroelastic materials with anisotropic permeability and compressible constituents. By applying Fourier expansions, Hankel transforms and Laplace transforms to the state variables involved in the governing equations of poroelasticity with respect to the circumferential, radial and time coordinates, respectively, the analytical layer-element (i.e. a symmetric stiffness matrix) is derived, which describes the relationship between the transformed generalized stresses and displacements at the surface (z = 0) and those at an arbitrary depth z, considering the corresponding boundary and continuity conditions at the layer interfaces, the global stiffness matrix of a multilayered system is assembled in the transformed domain. The actual solutions in the physical domain are acquired by applying numerical quadrature schemes for the inversion of the Laplace–Hankel transform. Finally, numerical calculation is presented to investigate the influence of layering and poroelastic material parameters on consolidation process. 相似文献
138.
Effect of solvent type on polycondensation of TEOS catalyzed by DBTL as used for stone consolidation 总被引:1,自引:0,他引:1
Carmen Salazar-Hernández Ramón Zárraga Sergio Alonso Satoshi Sugita Sergio Calixto Jorge Cervantes 《Journal of Sol-Gel Science and Technology》2009,49(3):301-310
We have investigated the effect of solvent in the sol–gel process of tetraethylorthosilicate (TEOS) when di-n-butyltin dilaurate (DBTL) is used as polycondensation catalyst. Two sets of materials similar to those employed in the field
of stone consolidation were prepared in the laboratory by using either protic or aprotic solvents: (1) xerogels from TEOS/DBTL,
and (2) composites from TEOS/colloidal silica particles/DBTL. The results have shown that the solvent directly influences
the aggregation pathway of the condensates. For a mixture of methyl ethyl ketone/acetone (aprotic solvents), gels with a higher
degree of condensation were obtained. In the case of TEOS xerogels, the materials are essentially non-porous. Additionally,
the incorporation of colloidal silica particles induces an important increase in porosity, which is even more dramatic when
ethanol is used as solvent, through the formation of micro and mesoporous materials as the concentration of particles is increased.
A TEOS polymerization pathway is suggested depending on which system of solvents is used. Various analytical techniques were
used to characterize the materials obtained. 相似文献
139.
There is limited information regarding the nature of plant and animal residues used as adhesives, fixatives and pigments found on Australian Aboriginal artefacts. This paper reports the use of FTIR in combination with the chemometric tools principal component analysis (PCA) and hierarchical clustering (HC) for the analysis and identification of Australian plant and animal fixatives on Australian stone artefacts. Ten different plant and animal residues were able to be discriminated from each other at a species level by combining FTIR spectroscopy with the chemometric data analysis methods, principal component analysis (PCA) and hierarchical clustering (HC). Application of this method to residues from three broken stone knives from the collections of the South Australian Museum indicated that two of the handles of knives were likely to have contained beeswax as the fixative whilst Spinifex resin was the probable binder on the third. 相似文献
140.