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31.
The influence of electric field and temperature on power consumption of piezoelectric actuated integrated structure is studied by using a single degree of freedom mass-spring-damper system model coupled with a piezoactuator. The material lead zirconate titanate, is considered as it is capable of producing relatively high strains (e.g., 3000με). Actuators are often subject to high electric fields to increase the induced strain produced, resulting in field dependant piezoelectric coefficient d31, dielectric coefficient ε33 and dissipation factor δ. Piezostructures are also likely to be used across a wide range of temperatures in aerospace and undersea operations. Again, the piezoelectric properties can vary with temperature. Recent experimental studies by physics researchers have looked at the effect of high electric field and temperature on piezoelectric properties. These properties are used together with an impedance based power consumption model. Results show that including the nonlinear variation of dielectric permittivity and dissipation factor with electric field is important. Temperature dependence of the dielectric constant also should be considered. 相似文献
32.
We have designed and implemented a visual programming environment, Hyper-flow on the PenPoint operating system. We call it HF/PP for short. Its primary goal is to provide a framework for UDUI in educational applications. The design of HF/PP, which uses only a pen and a microphone for input, is part of a research project to develop a pen based computer system for teaching preschool through twelfth grade mathematics. The article discusses the UDUI capabilities of HF/PP, represented by the programming constructs; form and formula, or the form/formula paradigm. To explain the paradigm, and other HF/PP constructs, we present three examples: converting between Fahrenheit and Celsius, designing arithmetic worksheets, and querying student records 相似文献
33.
34.
Sandeep Dasgupta Amey Karkare Vinay Kr Reddy 《Innovations in Systems and Software Engineering》2013,9(2):79-93
We present a static shape analysis technique to infer the shapes of the heap structures created by a program at run time. Our technique is field sensitive in that it uses field information to compute the shapes. The shapes of the heap structures are computed using two components: (a) Boolean functions that capture the shape transitions due to the update of a field in a structure, and (b) through path matrices that store approximate path information between two pointer variables. We classify the shapes as one of Tree, Directed Acyclic Graph (DAG) and Cycle. The novelty of our approach lies in the way we use field information to remember the fields that cause a heap structure to have a particular shape (Tree, DAG or Cycle). This allows us to easily identify the field updates that cause shape transitions from Cycle to DAG, from Cycle to Tree and from DAG to Tree. This makes our analysis more precise as compared to earlier shape analyses that ignore the fields participating in the formation of a shape. We implemented our analysis in GCC as a dynamic plug-in as an interprocedural data-flow analysis and evaluated it on some standard benchmarks against a field-insensitive shape analysis technique as a baseline approach. We are able to achieve significant precision as compared to the baseline analysis (at the cost of increase in analysis time). In particular, we are able to infer more precise shapes for 4 out 7 Olden benchmarks, and never detect more cycles than the baseline analysis. We further suggest enhancements to improve the precision of our analysis under some constraints and to improve the analysis time at the cost of precision. 相似文献
35.
Amey Apte Kosar Mozaffari Farnaz Safi Samghabadi Jordan A. Hachtel Long Chang Sandhya Susarla Juan Carlos Idrobo David C. Moore Nicholas R. Glavin Dmitri Litvinov Pradeep Sharma Anand B. Puthirath Pulickel M. Ajayan 《Advanced materials (Deerfield Beach, Fla.)》2020,32(24):2000006
Since graphene, a variety of 2D materials have been fabricated in a quest for a tantalizing combination of properties and desired physiochemical behavior. 2D materials that are piezoelectric, i.e., that allow for a facile conversion of electrical energy into mechanical and vice versa, offer applications for sensors, actuators, energy harvesting, stretchable and flexible electronics, and energy storage, among others. Unfortunately, materials must satisfy stringent symmetry requirements to be classified as piezoelectric. Here, 2D ultrathin single-crystal molybdenum oxide (MoO2) flakes that exhibit unexpected piezoelectric-like response are fabricated, as MoO2 is centrosymmetric and should not exhibit intrinsic piezoelectricity. However, it is demonstrated that the apparent piezoelectricity in 2D MoO2 emerges from an electret-like behavior induced by the trapping and stabilization of charges around defects in the material. Arguably, the material represents the first 2D electret material and suggests a route to artificially engineer piezoelectricity in 2D crystals. Specifically, it is found that the maximum out-of-plane piezoresponse is 0.56 pm V−1, which is as strong as that observed in conventional 2D piezoelectric materials. The charges are found to be highly stable at room temperature with a trapping energy barrier of ≈2 eV. 相似文献
36.
37.
Yu-Sung Wu Vinita Apte Saurabh Bagchi Sachin Garg Navjot Singh 《International Journal of Information Security》2009,8(3):153-172
In this article, we present the design of an intrusion detection system for voice over IP (VoIP) networks. The first part
of our work consists of a simple single- component intrusion detection system called Scidive. In the second part, we extend the design of Scidive and build a distributed
and
correlation-based intrusion detection system called Space
Dive. We create several attack scenarios and evaluate the accuracy and efficiency of the system in the face of these attacks.
To the best of our knowledge, this is the first comprehensive look at the problem of intrusion detection in VoIP systems.
It includes treatment of the challenges faced due to the distributed nature of the system, the nature of the VoIP traffic,
and the specific kinds of attacks at such systems.
Y.-S. Wu and V. Apte contributed equally to the paper. 相似文献
38.
R. S. Sonawane S. K. Apte B. B. Kale M. K. Dongare 《Metallurgical and Materials Transactions B》2000,31(1):35-41
Reduction of celestite (SrSO4) powder with particles of active charcoal has been studied extensively in the absence and presence of catalysts. The optimum
temperature at the charging zone has been optimized to get a maximum water-soluble strontium sulfide value. The strontium
value has been analyzed using a chemical method, which was verified by the instrumental method using an inductively coupled
plasma-optical emission spectrophotometer (ICP-OES). The conversion-time data have been analyzed by using a modified volume-reaction
(MVR) model, and the effect of the catalyst on kinetic parameters has been elucidated. It was found that potassium carbonate,
potassium dichromate, sodium carbonate, and sodium dichromate catalysts were found to enhance the reaction rate quite satisfactorily
in the reduction of the celestite (SrSO4). 相似文献
39.
Liladhar B. Kumbhare Amey P. Wadawale Vimal K. Jain Monika Sieger Wolfgang Kaim 《Inorganic chemistry communications》2010,13(4):475-478
Monoselenocarboxylate–bridged binuclear complexes of RhIII and IrIII, [(Cp1MCl)2(μ-SeCOAr)2] (1) (M = Rh or Ir; Cp1 = pentamethylcyclopentadienyl; Ar = Ph, C6H4Me–4), have been isolated either by the reaction between [Cp12M2(μ-Cl)2Cl2] with KSeCOAr in acetonitrile or by treatment of [Cp1MCl(solvent)2][PF6] with KSeCOAr in acetone. The novel binuclear complexes, [Cp1IrCl(μ-SeCOAr)(κ2-SeCOC6H3R–)IrCp1] (2) (R = H or Me-4) with ortho-metallation at one of the iridium centres have been isolated following the use of excess AgPF6. The single crystal structure of [Cp1IrCl(μ-SeCOC6H5)(κ2-SeCOC6H4–)IrCp1] (2a) exhibits two phenylcarboselenolate moieties situated in syn fashion with respect to the “Ir2Se2” plane, one of which leans towards the metal centre in order to undergo ortho-metallation after iridium–chlorine bond dissociation. 相似文献
40.
A highly sensitive, selective, and rapid, whole-cell-based electrochemical biosensor was developed for detection of the persistent organochlorine pesticide γ-hexachlorocyclohexane (γ-HCH), commonly known as lindane. The gene linA2 encoding the enzyme γ-hexachlorocyclohexane (HCH) dehydrochlorinase (LinA2), involved in the initial steps of lindane (γ-HCH) biotransformation, was cloned and overexpressed in Escherichia coli . The lindane-biodegrading E. coli cells were immobilized on polyaniline film. The rapid and selective degradation of lindane and concomitant generation of hydrochloric acid by the recombinant E. coli cells in the microenvironment of polyaniline led to a change in its conductivity, which was monitored by pulsed amperometry. The biosensor could detect lindane in the part-per-trillion concentration range with a linear response from 2 to 45 ppt. The sensor was found to be selective to all the isomers of hexachlorocyclohexane (HCH) and to pentachlorocyclohexane (PCCH) but did not respond to other aliphatic and aromatic chlorides or to the end product of lindane degradation, i.e., trichlorobenzene (TCB). The sensor also did not respond to other commonly used organochlorine pesticides like DDT and DDE. On the basis of experimental results, a rationale has been proposed for the excellent sensitivity of polyaniline as a pH sensor for detection of H(+) ions released in its microenvironment. 相似文献