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排序方式: 共有1523条查询结果,搜索用时 296 毫秒
31.
Luis Alvarez‐Icaza Oscar Rosas‐Jaimes María Elena Lárraga 《Asian journal of control》2017,19(2):494-509
A framework for stability analysis of local on‐ramp metering control strategies based on the cell transmission model is presented. Within this framework, it is possible to formulate Lyapunov and input‐state stability results for on‐ramp metering control strategies in an open section of highway with on‐ramps. Using this analysis, recommendations for the design of on‐ramp metering control laws set points are derived. Two examples on the use of such analysis are presented. One deals with the stability analysis of a local on‐ramp metering control law and the other with the design of a disturbance observer that, used in combination with the local on‐ramp metering control law, provides a more robust response to traffic regulation. Simulation results are included that confirm the possibility of using this framework to test the impact of local on‐ramp metering control strategies. 相似文献
32.
Extensive research has been carried out in multiresolution models for many decades. The tendency in recent years has been
to harness the potential of GPUs to perform the level-of-detail extraction on graphics hardware. The aim of this work is to
present a new level-of-detail scheme based on triangles which is both simple and efficient. In this approach, the extraction
process updates vertices instead of indices, thus providing a perfect framework for adapting the algorithms to work completely
on GPU shaders. One of the key aspects of our proposal is the need for just a single rendering pass in order to obtain the
desired geometry. Moreover, coherence among the different approximations is maximized by means of a symmetric extraction algorithm,
which performs the same process when refining and coarsening the mesh. Lastly, we also introduce different uses of the scheme
to offer continuous and view-dependent resolution. 相似文献
33.
Ann Q. Gates Steve Roach Oscar Mondragon Nelly Delgado 《Electronic Notes in Theoretical Computer Science》2001,55(2):164-180
Software engineering strives to enable the economic construction of software systems that behave reliably, predictably, and safely. In other engineering disciplines, safety is assured in part by detailed monitoring of processes. In software, we may achieve some level of confidence in the operation of programs by monitoring their execution. DynaMICs is a software tool that facilitates the collection and use of constraints for software systems. In addition, it supports traceability by mapping constraints to system artifacts. Constraint specifications are stored separately from code; constraint-monitoring code is automatically generated from the specifications and inserted into the program at appropriate places; and constraints are verified at execution time. These constraint checks are triggered by changes made to variable values. We describe the architecture of DynaMICs, discuss alternative verification techniques, and outline research directions for the DynaMICs project. 相似文献
34.
35.
Marcel P. C. M. Krijn Siebe T. de Zwart Dick K. G. de Boer Oscar H. Willemsen Maarten Sluijter 《Journal of the Society for Information Display》2008,16(8):847-855
Abstract— An attractive concept for 3‐D displays is the one based on LCDs equipped with lenticular lenses. This enables autostereoscopic multiview 3‐D displays without a loss in brightness. A general issue in multiview 3‐D displays is their relatively low spatial resolution because the pixels are divided among the different views. To overcome this problem, we have developed switchable displays, using liquid‐crystal (LC) filled switchable lenticulars. In this way, it is possible to have a high‐brightness 3‐D display capable of fully exploiting the native 2‐D resolution of the underlying LCD. The feasibility of LC‐filled switchable lenticulars was shown in several applications. For applications in which it is advantageous to be able to display 3‐D and 2‐D content simultaneously, a 42‐in. locally switchable prototype having a matrix electrode structure was developed. These displays were realized using cylindrically shaped lenticular lenses in contact with LC. An alternative for these are lenticulars based on gradient‐index (GRIN) LC lenses. Preliminary results for such switchable GRIN lenses are presented as well. 相似文献
36.
On spiking neural P systems and partially blind counter machines 总被引:1,自引:0,他引:1
A k-output spiking neural P system (SNP) with output neurons, , generates a tuple of positive integers if, starting from the initial configuration, there is a sequence of steps such that during the computation,
each O
i
generates exactly two spikes aa (the times the pair aa are generated may be different for different output neurons) and the time interval between the first a and the second a is n
i
. After the output neurons generate their pairs of spikes, the system eventually halts. We give characterizations of sets
definable by partially blind multicounter machines in terms of k-output SNPs operating in a sequential mode. Slight variations of the models make them universal. 相似文献
37.
Authentication and authorization in many distributed systems rely on the use of cryptographic credentials that in most of
the cases have a defined lifetime. This feature mandates the use of mechanisms able to determine whether a particular credential
can be trusted at a given moment. This process is commonly named validation. Among available validation mechanisms, the Online Certificate Status Protocol (OCSP) stands out due to its ability to carry
near real time certificate status information. Despite its importance for security, OCSP faces considerable challenges in
the computational Grid (i.e. Proxy Certificate’s validation) that are being studied at the Global Grid Forum’s CA Operations
Work Group (CAOPS-WG). As members of this group, we have implemented an OCSP validation infrastructure for the Globus Toolkit
4, composed of the CertiVeR Validation Service and our Open GRid Ocsp (OGRO) client library, which introduced the Grid Validation Policy. This paper summarizes our experiences on that work and the results obtained up to now. Furthermore we introduce the prevalidation concept, a mechanism analogous to the Authorization Push-Model, capable of improving OCSP validation performance in Grids.
This paper also reports the results obtained with OGRO’s prevalidation rules for Grid Services as a proof of concept.
相似文献
Oscar MansoEmail: |
38.
Saroul L Figueiredo O Hersch RD 《IEEE transactions on visualization and computer graphics》2006,12(1):26-35
Curved cross-sections extracted from medical volume images are useful for analyzing nonplanar anatomic structures such as the aorta arch or the pelvis. For visualization and for performing distance measurements, extracted surface sections need to be adequately flattened. We present two different distance preserving surface flattening methods which preserve distances according to a user-specified center of interest and according to user-specified orientations. The first method flattens surface sections by preserving distances along surface curves located within planes having a user specified constant orientation. The second method flattens surfaces along curves located within radial planes crossing the center of interest. We study and compare the properties of the two flattening methods by analyzing their distortion maps. Thanks to a multiresolution approach, we provide surface flattening at interactive rates, allowing users to displace their focus point while visualizing the resulting flattened surface. These distance preserving flattening methods provide new means of inspecting curved cross-sections extracted from medical images. 相似文献
39.
A simple problem concerning evaluation of programs is shown to be nonelementary recursive. The problem is the following: Given an input-free programP (i.e. all variables are initially 0) without nested loops using only instructions of the formx ← 1, x ← x + y, \(x \leftarrow x\dot - y\) ,do x... end, doesP output 0? This problem has time complexity \(2^{2^{ {\mathinner{\mkern2mu\raise1pt\hbox{.}\mkern2mu \raise4pt\hbox{.}\mkern2mu\raise7pt\hbox{.}\mkern1mu}} ^2 } } \) }cn-levels for some constantc. Other results are presented which show how the complexity of the 0-evaluation problem changes when the nonlooping instructions are varied. For example, it is shown that 0-evaluation is PSPACE-complete even for the case when the nonlooping instructions are onlyx ← x + 1,if x = 0then y ←y \(y \leftarrow y\dot - 1\) . 相似文献
40.
Let be the class of real-time nondeterministic one-counter machines whose counters make at mostone reversal. Let 1 (respectively, 2) be the subclass consisting of machines whose only nondeterministic move is in the choice of when to reverse the counter (respectively, when to start using the counter). 1 and 2 are among the simplest known classes of machines for which the universe problem has been shown undecidable. (The universe problem for a class of machines is the problem of deciding if an arbitrary machine in the class accepts all its inputs.) Here, we show that the classes of languages accepted by machines in 1 and 2 are incomparable. Moreover, the union of the language classes is properly contained in the class defined by . We also, briefly, look at the closure properties of these machines.This research was supported in part by NSF Grant MCS78-01736. 相似文献