全文获取类型
收费全文 | 12811篇 |
免费 | 393篇 |
国内免费 | 58篇 |
专业分类
电工技术 | 260篇 |
综合类 | 16篇 |
化学工业 | 2274篇 |
金属工艺 | 367篇 |
机械仪表 | 361篇 |
建筑科学 | 219篇 |
矿业工程 | 73篇 |
能源动力 | 704篇 |
轻工业 | 1171篇 |
水利工程 | 190篇 |
石油天然气 | 82篇 |
无线电 | 1623篇 |
一般工业技术 | 2772篇 |
冶金工业 | 1544篇 |
原子能技术 | 198篇 |
自动化技术 | 1408篇 |
出版年
2024年 | 39篇 |
2023年 | 177篇 |
2022年 | 506篇 |
2021年 | 504篇 |
2020年 | 409篇 |
2019年 | 408篇 |
2018年 | 553篇 |
2017年 | 514篇 |
2016年 | 483篇 |
2015年 | 280篇 |
2014年 | 446篇 |
2013年 | 886篇 |
2012年 | 518篇 |
2011年 | 676篇 |
2010年 | 540篇 |
2009年 | 531篇 |
2008年 | 476篇 |
2007年 | 389篇 |
2006年 | 331篇 |
2005年 | 263篇 |
2004年 | 244篇 |
2003年 | 219篇 |
2002年 | 180篇 |
2001年 | 143篇 |
2000年 | 147篇 |
1999年 | 156篇 |
1998年 | 355篇 |
1997年 | 231篇 |
1996年 | 251篇 |
1995年 | 219篇 |
1994年 | 182篇 |
1993年 | 171篇 |
1992年 | 143篇 |
1991年 | 151篇 |
1990年 | 114篇 |
1989年 | 108篇 |
1988年 | 130篇 |
1987年 | 109篇 |
1986年 | 89篇 |
1985年 | 115篇 |
1984年 | 94篇 |
1983年 | 107篇 |
1982年 | 99篇 |
1981年 | 88篇 |
1980年 | 78篇 |
1979年 | 54篇 |
1978年 | 46篇 |
1977年 | 56篇 |
1976年 | 76篇 |
1975年 | 32篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
The tracking of objects using distributed multiple sensors is an important field of work in the application areas of autonomous robotics, military applications, and mobile systems. In this survey, we review a number of computationally intelligent methods that are used for developing robust tracking schemes through sensor data fusion. The survey discusses the application of the various algorithms at different layers of the JDL model and highlights the weaknesses and strengths of the approaches in the context of different applications 相似文献
992.
A. Singh 《AI & Society》2007,21(1-2):27-46
The paper explores the relation between reason and action as it emerges from the texts of āyurveda. Life or Ayus (commonly understood as life-span) is primary subject matter of Ayurveda. Life is a locus of experience, action and disposition. Experiences and actions are differentially determined by dispositions that characterize the organism; otherwise all living organisms will be identical. Ayus of each living being is uniquely individual and remains constant between birth and death. In this journey, upkeep of ayus is the purpose of āyurveda or science of life. Ayurveda is a science of experienced matter as well as of experienced body. The living body is critically dependent on the influx of matter for its upkeep. āyurveda offers a conceptual system to reason about balance and imbalances of the system and the causal role of the material flux through the system. This sensate matter is causally open and makes room for definite causal role for the individual and the effective insertion of the felt-purpose of action. Some of the strengths of Ayurveda are brought forth in the paper such as (a) reasoning out the compatibility between the bodily processes and the selection of the natural products for diet and drug, (b) role for heuristics in medical diagnosis, which takes into cognizance the particularity of each living body and the teleology evident in the very act of diagnostic reasoning. The paper shows that āyurvedic theory is built on experiential datum whereas scientific medical theory is built on experience-independent datum. āyurveda explores causal efficacy of ‘secondary qualities’ whereas scientific medicine explores causal efficacy of ‘primary qualities’. The actionable experiential reasoning is at the foundations of āyurveda whereas modern medical science is ab initio saddled with difficult ‘hiatus theoreticus’ between theory and practice. For Ayurveda it is experience of qualities that discloses behavior of matter. The types of qualities that appear in experience have a special significance for theorizing about the actions of matter with the help of qualities. The paper explores the relation between experience of qualities and the method of science. It shows how efficacy of medical practice is based on the foundational stance of experiential realism in theory. To bring the point home, the paper borrows Aristotalian concepts to show how the relation between phantasm and phronesis is honored in the very theory of āyurveda. 相似文献
993.
Mandeep Singh Ramdev Rohit Bajaj Ruchika Gupta 《New Review of Information Networking》2020,25(1):71-82
ABSTRACT Wireless Interoperability for Multiple Access (WiMAX) is one of the emerging fields of high-speed wireless communication that has enormous capabilities due to its range and the connection speed. Like wireless local area networks (LANs), WiMAX networks implement multiple quality of service (QoS) frameworks at the Media Access Control (MAC) level for assured data, voice, and video services. The question of ensuring QoS is basically how to distribute available resources to users in order to satisfy QoS parameters such as latency, jitter and throughput requirements. IEEE 802.16 standard does not have any particular guidelines on scheduling of incoming and outgoing data. This has caught the attention of researchers working on WiMAX. This article discusses the various issues in WiMAX along with a classification of various scheduling approaches based upon the type of scheduler for the sake of better understanding the scheduling problem and analyzing various available theories. 相似文献
994.
Umamaheswara Konda Tarunraj Singh Puneet Singla Peter Scott 《Environmental Modelling & Software》2010,25(12):1608-1618
Atmospheric dispersion is a complex nonlinear physical process with numerous uncertainties in model parameters, inputs, source parameters, initial and boundary conditions. Accurate propagation of these uncertainties through the dispersion models is crucial for a reliable prediction of the probability distribution of the states and assessment of risk. A simple three-dimensional Gaussian puff-based dispersion model is used as a test case to study the effect of uncertainties in the model parameters and initial conditions on the output concentration. A polynomial chaos based approach is used to numerically investigate the evolution of the model output uncertainties due to initial condition and parametric uncertainties. The polynomial chaos solution is found to be an accurate approximation to ground truth, established by Monte Carlo simulation, while offering an efficient computational approach for large nonlinear systems with a relatively small number of uncertainties. 相似文献
995.
C-PSA: Constrained Pareto simulated annealing for constrained multi-objective optimization 总被引:2,自引:0,他引:2
In recent years, evolutionary algorithms (EAs) have been extensively developed and utilized to solve multi-objective optimization problems. However, some previous studies have shown that for certain problems, an approach which allows for non-greedy or uphill moves (unlike EAs), can be more beneficial. One such approach is simulated annealing (SA). SA is a proven heuristic for solving numerical optimization problems. But owing to its point-to-point nature of search, limited efforts has been made to explore its potential for solving multi-objective problems. The focus of the presented work is to develop a simulated annealing algorithm for constrained multi-objective problems. The performance of the proposed algorithm is reported on a number of difficult constrained benchmark problems. A comparison with other established multi-objective optimization algorithms, such as infeasibility driven evolutionary algorithm (IDEA), Non-dominated sorting genetic algorithm II (NSGA-II) and multi-objective Scatter search II (MOSS-II) has been included to highlight the benefits of the proposed approach. 相似文献
996.
Brett Abarbanel Bo Bernhard A. K. Singh Anthony Lucas 《Behaviour & Information Technology》2015,34(10):1005-1021
This study empirically tests a stimulus–organism–response (S–O–R) structural model that proposes that an online casino's atmospheric cues and functional qualities influence individuals' affective and cognitive responses, which in turn impact consumer behavioural intentions. Using self-reported data from a primarily US-based sample, analysed elements of the online gambling site stimulus included high and low task-relevant cues, financial trust, and gambling value. Demographic characteristics were found to moderate the relationship between the stimulus and internal satisfaction, with demographic group differences found among all stimulus constructs. Results emphasise the significant role that atmospherics and functional qualities play in generating positive behaviours from online gamblers, with additional implications in marketplace competitiveness and in responsible gambling practices. 相似文献
997.
Multimedia Tools and Applications - Large amount of multi-media content, generated by various image capturing devices, is shared and downloaded by millions of users across the globe, every second.... 相似文献
998.
Cloud computing is becoming a profitable technology because of it offers cost-effective IT solutions globally. A well-designed task scheduling algorithm ensures the optimal utilization of clouds resources and reducing execution time dynamically. This research article deals with the task scheduling of inter-dependent subtasks on unrelated parallel computing machines in a cloud computing environment. This article considers two variants of the problem-based on two different objective function values. The first variant considers the minimization of the total completion time objective function while the second variant considers the minimization of the makespan objective function. Heuristic and meta-heuristic (HEART) based algorithms are proposed to solve the task scheduling problems. These algorithms utilize the property of list scheduling algorithm of unrelated parallel machine scheduling problem. A mixed integer linear programming (MILP) formulation has been provided for the two variants of the problem. The optimal solution is obtained by solving MILP formulation using A Mathematical Programming Language (AMPL) software. Extensive numerical experiments have been performed to evaluate the performance of proposed algorithms. The solutions obtained by the proposed algorithms are found to out-perform the existing algorithms. The proposed algorithms can be used by cloud computing service providers (CCSPs) for enhancing their resources utilization to reduce their operating cost. 相似文献
999.
Sachin Singh Sushil Puradkar Yugyung Lee 《Information Systems and E-Business Management》2006,4(4):421-439
Ubiquitous computing refers to building a global computing environment where seamless and invisible access to computing resources is provided to the user. Pervasive computing deals with acquiring context knowledge from the environment and providing dynamic, proactive and context-aware services to the user. A Ubiquitous computing environment is created by sharing knowledge and information between Pervasive computing environments. In this paper we propose a framework that uses the potential of the Semantic Web to weave Pervasive computing environments into a Ubiquitous computing environment. We discuss how the collaboration of these Pervasive environments can create an effective Ubiquitous computing environment referred herein as the Integrated Global Pervasive Computing Framework (IGPF). We test the effectiveness of the Ubiquitous environment through a small scenario from a prototype system that we have implemented over this framework to handle medical emergency scenario. 相似文献
1000.
Abstract. The Online Maximal Dense Tree problem is as follows: given a weighted directed graph and a source node, users issue online requests for connection to
the source node. A request can either be accepted or rejected (the admission control decision). If the connection request
is accepted, it must be connected to the source or to a node previously connected to the source (the routing decision). The
objective is to maximize the total number of connections while keeping the connection density , i.e. the ratio of accepted requests to the weight of the spanning tree, sufficiently high.
The primary motivation for the Maximal Dense Tree problem is the Online Capacitated Multicast admission control and routing problem. In the Online Capacitated Multicast problem, we are given a communication network with limited link capacities and a set of signal source nodes. Users generate
online requests for connection to the signal sources, and the network administrator has to make the admission control and
routing decisions. The goal of the network administrator is to maximize the total number of users connected subject to the
network capacity constraints.
The Online Maximal Dense Tree problem is also faced by a cable TV operator who wishes to connect as many customers as possible while keeping down the
amount of wiring per customer. Informally, the Online Maximal Dense Tree algorithm must ``gamble' on certain geographic areas, connecting nodes which are unprofitable to start with, in the hope
that eventually enough requests will arrive in its vicinity to make the investment profitable.
In this paper we present a randomized online algorithm for the Maximal Dense Tree problem that guarantees acceptance of a
(1- ɛ) factor of the requests accepted by the optimum offline algorithm with the expectation of density being at most polylogarithmically
lower than that of the offline algorithm. This yields an online capacitated multicast algorithm whose throughput is only poly-logarithmically lower than that of the optimum offline algorithm.
Previous work on multicast routing and maximal dense tree problems either made probabilistic assumptions or resulted in linear performance gaps with the offline algorithm. Attempts to solve the Online Maximal Dense Tree problem have also lead to the development of the first polylogarithmic approximation algorithms for the k -MST and the Prize Collecting Salesman problems [AABV]. 相似文献