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241.
J. F. Muñoz‐Rosas E. Álvarez‐Verdejo M. N. Pérez‐Aróstegui L. Gutiérrez‐Gutiérrez 《Quality and Reliability Engineering International》2016,32(2):453-464
A control chart is a very common tool used to monitor the quality of business processes. An estimator of the process variability is generally considered to obtain the control limits of a chart when parameters of the process are unknown. Assuming Monte Carlo simulations, this paper first compares the efficiency of the various estimators of the process variability. Two empirical measures used to analyze the performance of control charts are defined. Results derived from various empirical studies reveal the existence of a linear relationship between the performance of the various estimators of the process variability and the performance of charts. The various Monte Carlo simulations are conducted under the assumption that the process is in both situations of in‐control and out‐of‐control. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
242.
An algorithm is presented for computing non-causal inverse dynamics for nonlinear noncollocated systems with non-zero initial conditions. A noncollocated system has a controlled degree of freedom not collocated with an actuator. Inverse dynamics is the process of computing actuator inputs to obtain desired responses at the controlled degrees of freedom. The algorithm uses an iterative frequency domain approach in computing the inverse dynamics. The algorithm is demonstrated via computer simulations of a flexible manipulator with Coulomb friction in one case, backlash in another case, and non-zero initial conditions in both cases. 相似文献
243.
Kindermann Sandra S.; Matteo Terrence M.; Morales Eduardo 《Canadian Metallurgical Quarterly》1993,24(2):224
A training-needs assessment was conducted at California School of Professional Psychology, Berkeley/Alameda, on students' beliefs about clinical competence, past training in HIV issues, and future training needs at the school. They perceived themselves to be somewhat competent in providing clinical services to HIV patients and members of groups at high risk for HIV. A modest correlation was found between the students' total HIV training and perceived competence, but none was found between the multicultural emphasis in HIV education and their perceived competence. These findings suggest an ethical dilemma surrounding inadequately trained psychologists providing services to multicultural populations. Ethical issues concerning training standards and criteria for clinical competency are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
244.
Eduardo Sáenz-de-Cabezón L. Javier HernándezM. Teresa Rivas Esteban García-RuizVicente Marco Ignacio Pérez-MorenoF. Javier Sáenz-de-Cabezón 《Mathematics and computers in simulation》2011,82(1):2-14
This paper presents a new procedure to construct families of spatial approximation-prediction functions which depend on several parameters. The method is based on partitions of the unity. In order to find optimal functions in these families we introduce a Vietoris simplicial set associated to an influence radius. We consider error estimators induced by these Vietoris simplicial sets. A computational implementation of these mathematical models has been developed to be applied to any kind of finite discrete data. Our methods provide a useful tool for the analysis of the spatial distribution of species, which is imperative for developing accurate and efficient management of endangered and invasive species, biological conservation programs, etc. We demonstrate the application of our method to the analysis of the spatial distribution of the grape moth Lobesia botrana (Lepidoptera: Tortricidae) in the vineyards of La Rioja obtaining useful results for the management of this pest. 相似文献
245.
This paper presents a robustness analysis of the optimal solution of the step tracking problem in a one-degree of freedom control architecture, for the discrete-time multivariable (MIMO) case. It is shown that the resulting closed loop becomes arbitrarily fragile, i.e. the sensitivity peak becomes arbitrarily large, for certain reference directions. The cause of this problem is that the optimal controller depends on the reference direction. The paper shows that this dependence can be eliminated with an alternative formulation of the optimal problem where the cost is averaged over all reference directions. 相似文献
246.
This paper aims to analyze dual-purpose systems focusing the total cost optimization; a superstructure is proposed to present cogeneration systems and desalination technologies alternatives for the synthesis process. The superstructure consists of excluding components, gas turbines or conventional steam generators with excluding alternatives of supplying fuel for each combustion system. Also, backpressure or condensing/extraction steam turbine for supplying process steam could be selected. Finally one desalination unit chosen between electrically-driven or steam-driven reverse osmosis, multi-effect and multistage flash should be included. The analysis herein performed is based on energy and mass conservation equations, as well as the technological limiting equation of equipment. The results for ten different commercial gas turbines revealed that electrically-driven reverse osmosis was always chosen together with both natural gas and gasified biomass gas turbines. 相似文献
247.
This is a theoretical work for the characterization of homogeneous chemical reactions coupled to a reversible electrode process and analyzed by Additive Differential Pulse Voltammetry at spherical electrodes or microelectrodes. Explicit analytical expressions are presented for the CE and EC mechanisms valid for spherical electrodes of any radius and fast chemical reactions. These enable us to easily and rapidly analyze the response of these mechanisms even under very strong kinetic conditions.The ADPV technique proves to be very useful in the identification of the reaction mechanism and the characterization of the coupled chemical reaction by means of the values of the peak currents and potentials and the crossing potential, which can be measured with good accuracy from several ADPV experiments with different pulse heights. Simple criteria are given for discrimination between different situations where the electrode process is coupled to a homogeneous chemical reaction and, what is more difficult, to distinguish between an EC mechanism and an irreversible charge transfer process. Moreover, direct procedures for quantitative determination of kinetic and thermodynamic information are established. 相似文献
248.
249.
Daniel Casellas Antoni Lara David Frómeta David Gutiérrez Sílvia Molas Lluís Pérez Johannes Rehrl Clemens Suppan 《Metallurgical and Materials Transactions A》2017,48(1):86-94
The edge fracture is considered as a high risk for automotive parts, especially for parts made of advanced high strength steels (AHSS). The limited ductility of AHSS makes them more sensitive to the edge damage. The traditional approaches, such as those based on ductility measurements or forming limit diagrams, are unable to predict this type of fractures. Thus, stretch-flangeability has become an important formability parameter in addition to tensile and formability properties. The damage induced in sheared edges in AHSS parts affects stretch-flangeability, because the generated microcracks propagate from the edge. Accordingly, a fracture mechanics approach may be followed to characterize the crack propagation resistance. With this aim, this work addresses the applicability of fracture toughness as a tool to understand crack-related problems, as stretch-flangeability and edge cracking, in different AHSS grades. Fracture toughness was determined by following the essential work of fracture methodology and stretch-flangeability was characterized by means of hole expansions tests. Results show a good correlation between stretch-flangeability and fracture toughness. It allows postulating fracture toughness, measured by the essential work of fracture methodology, as a key material property to rationalize crack propagation phenomena in AHSS. 相似文献
250.
The UV spectra of tungsten oxide catalysts supported on alumina, titania and zirconia, and on titania–alumina and titania–zirconia mixed oxides are reported and discussed. Evidence is provided for the different electronic structure of supports and catalysts, which could affect the behavior of the tungsten oxide centres in the different cases. On alumina, tungsten oxide centres are “isolated” by the insulating support, while on titania-based materials they are likely in electronic contact with each other and with Ti centres through the support conduction band. In the case of WOx2013;ZrO2, the 5d levels of tungsten ions fall just below of the lower energy limit of the support conduction band. This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献