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71.
Experiments were performed to study the diffusion process between matrix and fracture while there is flow in fracture. 2-inch
diameter and 6-inch length Berea sandstone and Indiana limestone samples were cut cylindrically. An artificial fracture spanning
between injection and production ends was created and the sample was coated with heat-shrinkable teflon tube. A miscible solvent
(heptane) was injected from one end of the core saturated with oil at a constant rate. The effects of (a) oil type (mineral
oil and kerosene), (b) injection rates, (c) orientation of the core, (d) matrix wettability, (e) core type (a sandstone and
a limestone), and (f) amount of water in matrix on the oil recovery performance were examined. The process efficiency in terms
of the time required for the recovery as well as the amount of solvent injected was also investigated. It is expected that
the experimental results will be useful in deriving the matrix–fracture transfer function by diffusion that is controlled
by the flow rate, matrix and fluid properties. 相似文献
72.
Aastha Gupta Aditya Kaushik Manju Sharma 《Numerical Methods for Partial Differential Equations》2023,39(2):1220-1250
We propose a hybrid numerical scheme to discretize a class of singularly perturbed parabolic reaction–diffusion problems with robin-boundary conditions on an equidistributed grid. The hybrid difference scheme is developed by using a modified backward difference scheme in time, a combination of the cubic spline and exponential spline difference scheme in space. The proposed scheme uses a cubic spline difference scheme for the discretization of robin-boundary conditions. For the time discretization of the problem, we use the standard uniform mesh while a layer adapted equidistributed grid is generated for the spatial discretization. By equidistributing a curvature-based monitor function, the spatial adaptive grid is able to capture the presence of parabolic boundary layers without using any prior information about the solution. Parameter uniform error estimates are derived to illustrate an optimal convergence of first-order in time and second-order in space for the proposed discretization. The accuracy of the proposed scheme is confirmed by the numerical experiments that underpin the theoretical analysis. 相似文献
73.
A highly regio- and diastereoselective reduction of various N-tert-butanesulfinyl ketimine esters with L-Selectride resulting in the formation of α-amino acids is reported. This method is quite general and also practical for the preparation of both enantiomers of aryl or aliphatic α-amino acids in high yields. 相似文献
74.
In oil recovery from fractured reservoirs, dynamic spontaneous imbibition (DSI) plays an important role. Conventional equations
used for characterizing dynamic spontaneous imbibition neglect the effects of the driving forces acting across the wetting
and non-wetting phases which are flowing in opposite directions. Such effects, defined as interfacial coupling effects (ICE),
are known to cause a decrease in the calculated flow rate in drainage processes. Moreover, none of the numerical models have
considered a variable inlet saturation (S*) for DSI. A new theoretical model has been developed using generalized transport equations to describe dynamic spontaneous
imbibition for immiscible two-phase flow processes. The inclusion of interfacial coupling effects provides a more accurate
way to describe dynamic spontaneous imbibition. Furthermore, the addition of variable inlet saturation allows one to establish
whether the inlet-face saturation (S*) increases from the initial saturation to 1−Sro, or whether it can remain constant and equal to one minus the residual saturation
to the non-wetting phase (1−Sro). 相似文献
75.
Realization of a Framework for Simulation-Based Large-Scale Shape Optimization Using Vertex Morphing
Ghantasala Aditya Najian Asl Reza Geiser Armin Brodie Andrew Papoutsis Efthymios Bletzinger Kai-Uwe 《Journal of Optimization Theory and Applications》2021,189(1):164-189
Journal of Optimization Theory and Applications - There is a significant tendency in the industry for automation of the engineering design process. This requires the capability of analyzing an... 相似文献
76.
Prashant S. Umare Ajaykumar J. Tiwari Robin Antony Gopal L. Tembe Bhavna Trivedi 《应用有机金属化学》2007,21(8):652-660
Complexes of titanium(IV) with bulky phenolic ligands such as 2‐tert‐butyl‐4 methylphenol, 2, 4‐di‐tert‐butyl phenol and 3,5‐di‐tert‐butyl phenol were prepared and characterized. These catalyst precursors, formulated as [Ti(OPh*)n(OPri)4?n] (OPh* = substituted phenol), were found to be active in polymerization of ethylene at higher temperatures in combination with ethylaluminum sesquichloride (Et3Al2Cl3) as co‐catalyst. It was observed that the reaction temperature and ethylene pressure had a pronounced effect on polymerization and the molecular weight of polyethylene obtained. In addition, this catalytic system predominantly produced linear, crystalline ultra‐low‐molecular‐weight polyethylenes narrow dispersities. The polyethylene waxes obtained with this catalytic system exhibit unique properties that have potential applications in surface coating and adhesive formulations. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
77.
For a connected graph G let L(G) denote the maximum number of leaves in any spanning tree of G. We give a simple construction and a complete proof of a result of Storer that if G is a connected cubic graph on n vertices, then L(G) ? [(n/4) + 2], and this is best possible for all (even) n. The main idea is to count the number of “dead leaves” as the tree is being constructed. This method of amortized analysis is used to prove the new result that if G is also 3-connected, then L(G) ? [(n/3) + (4/3)], which is best possible for many n. This bound holds more generally for any connected cubic graph that contains no subgraph K4 - e. The proof is rather elaborate since several reducible configurations need to be eliminated before proceeding with the many tricky cases in the construction. 相似文献
78.
Summary We prove that given a Noetherian ringR and a finitely generatedR-inoduleM, there exists a finite set of prime idealsΛ inR such that the depth of an arbitrary idealI onM is determined by the height ofI modulo each of the primes inΛ. As an application we answer a question raised by the second author and V. Srinivas concerning m-adic approximations of regular
sequences in a local ring.
This article was processed by the author using the Springer-Verlag TEX P Jourlg macro package 1991. 相似文献
79.
Trivedi K.S. Ramani S. Fricks R. 《Proceedings of the IEEE. Institute of Electrical and Electronics Engineers》2003,91(7):1023-1037
Real-time systems are an important class of process control systems that need to respond to events under time constraints, or deadlines. Such systems may also be required to deliver service in spite of hardware or software faults in their components. This fault-tolerant characteristic is especially critical in systems whose failure can cause economic disaster and/or loss of lives. This paper reports recent research in the area of analytical modeling of the three major characteristics of real-time systems: timeliness, dependability, and external environmental dependencies. The paper starts with a brief introduction to analytical modeling frameworks such as Markov models and stochastic petri nets. This is followed by an examination of advances in modeling response-time distributions, reliability, distributed messaging services, and software fault-tolerance in real-time systems. 相似文献
80.
Xiuping Li Jianjun Gao Choi Look Law Sheel Aditya 《International Journal of Infrared and Millimeter Waves》2003,24(10):1709-1718
This paper describes a simple method to check the performance of microprobe. The two-port S-parameters of the microprobe are determined by one-port S-parameters measurement using HP 8510XF Network Analyzer. Based on the measurement, an equivalent circuit model for the microprobe is presented and good agreement between the measurement results and modeling results is obtained. 相似文献