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71.
We present a framework for sequential decision making in problems described by graphical models. The setting is given by dependent discrete random variables with associated costs or revenues. In our examples, the dependent variables are the potential outcomes (oil, gas or dry) when drilling a petroleum well. The goal is to develop an optimal selection strategy of wells that incorporates a chosen utility function within an approximated dynamic programming scheme. We propose and compare different approximations, from naive and myopic heuristics to more complex look-ahead schemes, and we discuss their computational properties. We apply these strategies to oil exploration over multiple prospects modeled by a directed acyclic graph, and to a reservoir drilling decision problem modeled by a Markov random field. The results show that the suggested strategies clearly improve the naive or myopic constructions used in petroleum industry today. This is useful for decision makers planning petroleum exploration policies. 相似文献
72.
73.
The ground-state phases of two-dimensional spin-2 Bose–Einstein condensate with Rashba spin–orbit coupling are studied. For the equal strengths of the density-density interaction and the spin-exchange interaction, we classify the ground-state phases into four types of stable phases with spin–orbit coupling and spin singlet-pairing interaction in momentum space, i.e., the ring phase, the stripe phase, the triangular phase and the square phase. With increasing the spin–orbit coupling strength, the system undergoes a sequence phase transitions from the ring phase to the stripe phase, and to the square phase for the attractive spin singlet-pairing interaction (), and the system undergoes a sequence phase transitions from the ring phase to the stripe phase, to the triangular phase, and to the square phase for the repulsive spin singlet-pairing interaction (). 相似文献
74.
J. Llorca-Porcel M.A. Rodríguez-Valero M. Martínez-Escandell F. Rodríguez-Reinoso 《Journal of Analytical and Applied Pyrolysis》2008,82(1):163-169
Self-sintering semicokes were prepared by pyrolysis of an aromatic petroleum residue at 460–480 °C and pressures of 0.1–1.0 MPa. The evolution of gases and thermoplasticity from resultant semicokes were monitored by TGA and TMA, respectively. Sintering behaviour of the semicokes is extremely sensitive to pyrolysis conditions which determine contents of volatile matter and binder phase. Semicokes produced at 1.0 MPa have high volatile contents with excessive plasticity. Changes of temperature and soak time, used to reduce volatile matter contents induce reductions to the plasticity and sintering. A lower pyrolysis pressure has a similar effect. Although the operational window is narrow, heat-treated compacts (2500 °C) can be made with high density (1.9 g cm−3) and bending strengths >75 MPa. Using high-temperature pyrolysis (460 °C) with a post-treatment at 350–400 °C eliminates light components, without decreasing sintering properties. Compacts from these powders also exhibit high density (1.9 g cm−3) with higher bending strengths >90 MPa, comparable or superior to mesocarbon microbeads (MCMB) obtained from the same precursor. 相似文献
75.
Carvalho NB de Souza RL de Castro HF Zanin GM Lima AS Soares CM 《Applied biochemistry and biotechnology》2008,150(1):25-32
Amylases and lipases are highly demanded industrial enzymes in various sectors such as food, pharmaceuticals, textiles, and detergents. Amylases are of ubiquitous occurrence and hold the maximum market share of enzyme sales. Lipases are the most versatile biocatalyst and bring about a range of bioconversion reactions such as hydrolysis, inter-esterification, esterification, alcoholysis, acidolysis, and aminolysis. The objective of this work was to study the feasibility for amylolitic and lipolytic production using a bacterium strain isolated from petroleum contaminated soil in the same submerged fermentation. This was a sequential process based on starch and vegetable oils feedstocks. Run were performed in batchwise using 2% starch supplemented with suitable nutrients and different vegetable oils as a lipase inducers. Fermentation conditions were pH 5.0; 30 degrees C, and stirred speed (200 rpm). Maxima activities for amyloglucosidase and lipase were, respectively, 0.18 and 1,150 U/ml. These results showed a promising methodology to obtain both enzymes using industrial waste resources containing vegetable oils. 相似文献
76.
The feedback control scheme for a Bose‐Einstein condensate (BEC) in a double‐well trapping potential located in one arm of Mach‐Zehnder interferometer (MZI) is investigated. The off‐resonant light beam performs the phase probing in one of the wells, thus creating information about the number of atoms in this well. The parameters of the trapping potential are controlled via a feedback loop based on the measured output of the MZI. The problem is analyzed in the framework of master equations for hybrid quantum‐classical systems. Significant modifications of the stationary distribution of atoms over the wells are predicted. These distributions can effectively be controlled by the tunable phase shift in the other arm of the MZI. 相似文献
77.
Crude oil analysis has long been an inspiration for the development of analytical techniques. Especially mass spectrometry
has flourished as a result of the challenge these extremely complex problems offer. Here an overview of different analytical
methods is presented that shows different ways to analyze volatile and nonvolatile crude oil components. Focus has been placed
on the use of mass spectrometry and especially the new developments that have been introduced using the emerging technique
of Fourier transform ion cyclotron resonance mass spectrometry. These studies are examples of how far the development of analytical
methods has come for the task of studying such complex problems. 相似文献
78.
Using the generating function method to solve the master equation of Bose-Einstein condensate and to evaluate the growth rate, statistical fluctuation of condensate atoms, we find out that there is a plateau in the growth rate curve and a super-Poisson distribution observed. 相似文献
79.
《Physics letters. A》2014,378(16-17):1085-1090
The formations of n-order two-soliton bound states (TSBSs) in the Bose–Einstein condensates with spatiotemporally modulated nonlinearities are studied. Exact analytical expressions of the n-order TSBSs are derived by means of the similarity transformations. Further, the numerical simulations are carried out, consistent with the analytical results very well. The stability analysis shows that the solutions can be stable. Our results indicate that the attractive spatiotemporal inhomogeneous nonlinearities can support n-order TSBSs, which has the potential applications to the generation of matter-wave bright solitons in harmonic traps. 相似文献
80.
Transport of oil and gas-condensate mixtures of various compositions is found to be accompanied by a slight increase in viscosity in the coldest period when ground temperatures at depth of a condensate pipeline reach 0 – minus 4°С. Fall in temperature of oil fluids under study to minus 10 – minus 30°С is accompanied by a sharp increase in all structural and rheological parameters of the mixture. Even a slight amount of oil added to a gas-condensate mixture causes a significant decrease in viscosity in the negative temperature range. As a result, cloud and pour point of a mixture falls, its amount decreases, the structure of paraffin deposits changes. 相似文献