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141.
In the present investigation, Greigite-conducting polypyrrole nanocomposite (GPPy nanocomposite) was prepared, characterized and used to remove arsenite and arsenate from aqueous solution. Fe3S4 was synthesized using solvothermal synthetic method and it was grafted to conducting polypyrrole matrix. The nanocomposite was characterized using FE-SEM, EDX, XRD, FTIR, TGA/DSC and BET surface area. Kinetic studies revealed that the removal process followed first order kinetics. Batch isotherm studies were performed to determine the binding capacity. Thermodynamic parameters were also computed and it indicated the spontaneous nature of the process. Electrophoretic studies were carried out to determine the point of zero charge. 相似文献
142.
S. Tzamtzis N.S. Barekar N. Hari Babu J. Patel B.K. Dhindaw Z. Fan 《Composites Part A》2009,40(2):144-151
Particulate metal matrix composites (PMMCs) have attracted interest for application in numerous fields. The current processing methods often produce agglomerated particles in the ductile matrix and as a result these composites exhibit extremely low ductility. The key idea to solve the current problem is to adopt a novel Rheo-process allowing the application of sufficient shear stress (τ) on particulate clusters embedded in liquid metal to overcome the average cohesive force or the tensile strength of the cluster. In this study, cast A356/SiCp composites were produced using a conventional stir casting technique and a novel Rheo-process. The microstructure and properties were evaluated. The adopted Rheo-process significantly improved the distribution of the reinforcement in the matrix. A good combination of improved ultimate tensile strength (UTS) and tensile elongation (ε) is obtained. 相似文献
143.
This study made an attempt to develop ethnographic decision models to understand and improve iron-folic acid supplement procurement and compliance-related behaviors of poor urban pregnant women in Vadodara, India, based on data obtained through the use of qualitative research tools. Open-ended, in-depth interviews were conducted with 36 pregnant women (17-32 weeks of gestation) purposively selected from four urban slums. Fortnightly home visits were made to the houses of 20 pregnant women-family member pairs to elicit behaviors related to iron-folic acid supplement procurement and compliance at the household level, from which the ethnographic decision models were developed. The hemoglobin levels of these women were also assessed. Regular counseling until delivery, based on the ethnographic data, helped to improve compliance, which resulted in 95% of the women consuming over 90% of the required dose. The mean hemoglobin level also improved from 9.6 to 11.08 g/dl until the end of the last trimester. This study highlighted the need for qualitative ethnographic data to develop such models that would help in the understanding of specific behaviors that influence program acceptance. Such data would have policy-level implications, for example, developing appropriate information-education-communication material and counseling strategies. 相似文献
144.
QoS Recovery Schemes Based on Differentiated MPLS Services in All-Optical Transport Next Generation Internet 总被引:1,自引:0,他引:1
The Internet is evolving from best-effort service toward an integrated or differentiated service framework with quality-of-service (QoS) assurances that are required for new multimedia service applications. Given this increasing demand for high bandwidth Internet with QoS assurances in the coming years, an IP/MPLS-based control plane combined with a wavelength-routed dense wavelength division multiplexing (DWDM) optical network is seen as a very promising approach for the realization of future re-configurable transport networks. Fault and attack survivability issues concerning physical security in a DWDM all-optical transport network (AOTN) require a new approach taking into consideration AOTN physical characteristics. Furthermore, unlike in electronic networks that regenerate signals at every node, attack detection and isolation schemes may not have access to the overhead bits used to transport supervisory information between regenerators or switching sites to perform their functions. This paper presents an analysis of attack and protection problems in an AOTN. Considering this, we propose a framework for QoS guarantees based on the differentiated MPLS service (DMS) model and QoS recovery schemes against QoS degradation caused by devices failures or attack-induced faults in an AOTN. We also suggest how to integrate our attack management model into the NISTs simulator—modeling, evaluation and research of lightwave networks (MERLiN). 相似文献
145.
Minnie H. Patel Yasser Dessouky Sumeet SolankiElvin Carbonel 《Computers & Industrial Engineering》2006
In this paper, various deterministic models for determining optimal pickup times for air cargo from an airport and delivering it to a local distribution center for a global manufacturer are presented. The arrival times of the flights that can potentially bring air cargo are assumed to be deterministic and known. In addition, the custom clearance time for the air cargo and the traveling time from the airport to the local distribution center are assumed to be deterministic and known. These models are formulated mathematically as linear binary integer programming models without air cargo weight considerations. Deterministic formulations without air cargo weight information are shown to be related to the p-Median problem. The deterministic formulation of air cargo pickup times with air cargo weight consideration is shown to be a nonlinear binary integer programming model. The solutions of these models serve as an initial starting point to solve the stochastic problem with random arrival times of the flights and random custom clearance times and travel times. 相似文献
146.
Abowd G.D. Hayes G.R. Iachello G. Kientz J.A. Patel S.N. Stevens M.M. Truong K.N. 《Pervasive Computing, IEEE》2005,4(4):67-73
Conducting user-centered design is a primary challenge in ubiquitous computing. Two kinds of prototyping techniques can be particularly effective for developing mobile and ubiquitous computing applications: compound prototypes and situated experience prototypes. Compound prototypes combine the final product's user interface (UI) with a computational implementation that runs on a separate system without the resource constraints of the target device. This model lets researchers and designers evaluate a new application's physicality and aesthetics as well as its functionality. Situated experience prototypes, or paratypes, include experimental protocols that attempt to reproduce user interaction with the system in real situations, and can optionally use common prototyping instruments such as paper mock-ups or physical props. Using our Personal Audio Loop (PAL) project as a case study, we discuss how you can fruitfully employ compound prototypes and paratypes when designing and developing mobile and ubiquitous computing applications. 相似文献
147.
Sharma R.K. Bash C.E. Patel C.D. Friedrich R.J. Chase J.S. 《Internet Computing, IEEE》2005,9(1):42-49
Internet-based applications and their resulting multitier distributed architectures have changed the focus of design for large-scale Internet computing. Internet server applications execute in a horizontally scalable topology across hundreds or thousands of commodity servers in Internet data centers. Increasing scale and power density significantly impacts the data center's thermal properties. Effective thermal management is essential to the robustness of mission-critical applications. Internet service architectures can address multisystem resource management as well as thermal management within data centers. 相似文献
148.
Practical methods for constructing suffix trees 总被引:7,自引:0,他引:7
Yuanyuan Tian Sandeep Tata Richard A. Hankins Jignesh M. Patel 《The VLDB Journal The International Journal on Very Large Data Bases》2005,14(3):281-299
Sequence datasets are ubiquitous in modern life-science applications, and querying sequences is a common and critical operation
in many of these applications. The suffix tree is a versatile data structure that can be used to evaluate a wide variety of
queries on sequence datasets, including evaluating exact and approximate string matches, and finding repeat patterns. However,
methods for constructing suffix trees are often very time-consuming, especially for suffix trees that are large and do not
fit in the available main memory. Even when the suffix tree fits in memory, it turns out that the processor cache behavior
of theoretically optimal suffix tree construction methods is poor, resulting in poor performance. Currently, there are a large
number of algorithms for constructing suffix trees, but the practical tradeoffs in using these algorithms for different scenarios
are not well characterized.
In this paper, we explore suffix tree construction algorithms over a wide spectrum of data sources and sizes. First, we show
that on modern processors, a cache-efficient algorithm with O(n2) worst-case complexity outperforms popular linear time algorithms like Ukkonen and McCreight, even for in-memory construction.
For larger datasets, the disk I/O requirement quickly becomes the bottleneck in each algorithm's performance. To address this
problem, we describe two approaches. First, we present a buffer management strategy for the O(n2) algorithm. The resulting new algorithm, which we call “Top Down Disk-based” (TDD), scales to sizes much larger than have
been previously described in literature. This approach far outperforms the best known disk-based construction methods. Second,
we present a new disk-based suffix tree construction algorithm that is based on a sort-merge paradigm, and show that for constructing
very large suffix trees with very little resources, this algorithm is more efficient than TDD. 相似文献
149.
This article describes RISCBOT (RISCBOT name has been derived from RISC lab and ‘bot’ of robot, a modular 802.11 b-enabled mobile autonomous robot built at the RISC lab of the University of Bridgeport. RISCBOT localizes itself and successfully fulfills www – enabled online user requests and navigates to various rooms, employing a visual recognition algorithm. This article describes the mechanical design, hardware and software algorithms of the robot, and the web-based interface for communicating with the robot.
⋆RISC lab: Interdisciplinary Robotics, Intelligent Sensing and Control laboratory at the University of Bridgeport. 相似文献
150.
W. T. Luke Teacy Jigar Patel Nicholas R. Jennings Michael Luck 《Autonomous Agents and Multi-Agent Systems》2006,12(2):183-198
In many dynamic open systems, agents have to interact with one another to achieve their goals. Here, agents may be self-interested,
and when trusted to perform an action for another, may betray that trust by not performing the action as required. In addition,
due to the size of such systems, agents will often interact with other agents with which they have little or no past experience.
There is therefore a need to develop a model of trust and reputation that will ensure good interactions among software agents
in large scale open systems. Against this background, we have developed TRAVOS (Trust and Reputation model for Agent-based Virtual OrganisationS) which models an agent’s trust in an interaction partner.
Specifically, trust is calculated using probability theory taking account of past interactions between agents, and when there
is a lack of personal experience between agents, the model draws upon reputation information gathered from third parties.
In this latter case, we pay particular attention to handling the possibility that reputation information may be inaccurate. 相似文献