全文获取类型
收费全文 | 2786篇 |
免费 | 181篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 37篇 |
化学工业 | 783篇 |
金属工艺 | 50篇 |
机械仪表 | 128篇 |
建筑科学 | 128篇 |
矿业工程 | 8篇 |
能源动力 | 106篇 |
轻工业 | 443篇 |
水利工程 | 17篇 |
石油天然气 | 11篇 |
无线电 | 187篇 |
一般工业技术 | 369篇 |
冶金工业 | 95篇 |
原子能技术 | 11篇 |
自动化技术 | 595篇 |
出版年
2024年 | 11篇 |
2023年 | 37篇 |
2022年 | 73篇 |
2021年 | 149篇 |
2020年 | 112篇 |
2019年 | 132篇 |
2018年 | 110篇 |
2017年 | 115篇 |
2016年 | 125篇 |
2015年 | 98篇 |
2014年 | 142篇 |
2013年 | 244篇 |
2012年 | 179篇 |
2011年 | 216篇 |
2010年 | 174篇 |
2009年 | 160篇 |
2008年 | 120篇 |
2007年 | 124篇 |
2006年 | 109篇 |
2005年 | 79篇 |
2004年 | 63篇 |
2003年 | 53篇 |
2002年 | 54篇 |
2001年 | 32篇 |
2000年 | 33篇 |
1999年 | 23篇 |
1998年 | 19篇 |
1997年 | 22篇 |
1996年 | 20篇 |
1995年 | 16篇 |
1994年 | 14篇 |
1993年 | 16篇 |
1992年 | 5篇 |
1991年 | 6篇 |
1990年 | 5篇 |
1989年 | 5篇 |
1988年 | 6篇 |
1987年 | 4篇 |
1986年 | 8篇 |
1985年 | 7篇 |
1984年 | 9篇 |
1983年 | 13篇 |
1982年 | 5篇 |
1981年 | 3篇 |
1978年 | 5篇 |
1977年 | 3篇 |
1976年 | 2篇 |
1975年 | 3篇 |
1970年 | 2篇 |
1968年 | 1篇 |
排序方式: 共有2968条查询结果,搜索用时 15 毫秒
21.
Eduardo Arias-Marín Luis F. Ramos De Valle Oliverio Rodríguez-Fernndez Jesús Rodríguez-Velzquez 《乙烯基与添加剂工艺杂志》1995,1(4):217-222
The effect of elemental sulfur (S8) and tetramethyl thiuram disulfide (TMTD) on the chemical crosslinking of PVC is studied. The tensile strength, elongation at break, and gel content of crosslinked and uncrosslinked PVC molded samples, cured at different times in hot air, are evaluated. It was found that crosslinking PVC with TMTD improves its mechanical properties, and adding S8 produces a slight improvement. Also, the S8 presence accelerated the PVC/TMTD crosslinking reaction when the crosslinking reaction was carried out under shear forces, but not when the curing was done in hot air, where the S8 retards the process. 相似文献
22.
Leonardo Roberto da Silva Eduardo Carlos Bianchi Ronaldo Yoshinobu Fusse Rodrigo Eduardo Catai Thiago Valle Frana Paulo Roberto Aguiar 《International Journal of Machine Tools and Manufacture》2007,47(2):412-418
The quality of machined components is currently of high interest, for the market demands mechanical components of increasingly high performance, not only from the standpoint of functionality but also from that of safety. Components produced through operations involving the removal of material display surface irregularities resulting not only from the action of the tool itself, but also from other factors that contribute to their superficial texture. This texture can exert a decisive influence on the application and performance of the machined component. This article analyzes the behavior of the minimum quantity lubricant (MQL) technique and compares it with the conventional cooling method. To this end, an optimized fluid application method was devised using a specially designed nozzle, by the authors, through which a minimum amount of oil is sprayed in a compressed air flow, thus meeting environmental requirements. This paper, therefore, explores and discusses the concept of the MQL in the grinding process. The performance of the MQL technique in the grinding process was evaluated based on an analysis of the surface integrity (roughness, residual stress, microstructure and microhardness). The results presented here are expected to lead to technological and ecological gains in the grinding process using MQL. 相似文献
23.
24.
Pablo J. Blanco Pablo J. Sánchez Eduardo A. de Souza Neto Raúl A. Feijóo 《Archives of Computational Methods in Engineering》2016,23(2):191-253
A unified variational theory is proposed for a general class of multiscale models based on the concept of Representative Volume Element. The entire theory lies on three fundamental principles: (1) kinematical admissibility, whereby the macro- and micro-scale kinematics are defined and linked in a physically meaningful way; (2) duality, through which the natures of the force- and stress-like quantities are uniquely identified as the duals (power-conjugates) of the adopted kinematical variables; and (3) the Principle of Multiscale Virtual Power, a generalization of the well-known Hill-Mandel Principle of Macrohomogeneity, from which equilibrium equations and homogenization relations for the force- and stress-like quantities are unequivocally obtained by straightforward variational arguments. The proposed theory provides a clear, logically-structured framework within which existing formulations can be rationally justified and new, more general multiscale models can be rigorously derived in well-defined steps. Its generality allows the treatment of problems involving phenomena as diverse as dynamics, higher order strain effects, material failure with kinematical discontinuities, fluid mechanics and coupled multi-physics. This is illustrated in a number of examples where a range of models is systematically derived by following the same steps. Due to the variational basis of the theory, the format in which derived models are presented is naturally well suited for discretization by finite element-based or related methods of numerical approximation. Numerical examples illustrate the use of resulting models, including a non-conventional failure-oriented model with discontinuous kinematics, in practical computations. 相似文献
25.
This paper proposes a novel pose (position and orientation) consensus controller for networks of heterogeneous robots modeled in the operational space. The proposed controller is a distributed proportional plus damping scheme that, with a slight modification, solves both the leader–follower and leaderless consensus problems. A singularity‐free representation, unit quaternion, is used to describe the robots orientation, and the network is represented by an undirected and connected interconnection graph. Furthermore, it is shown that the controller is robust to interconnection variable time delays. Experiments with a network of two 6‐degrees‐of‐freedom robots are presented to illustrate the performance of the proposed scheme. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
26.
Gorka Epelde Eduardo Carrasco Gottfried Zimmermann Jan Alexandersson Robert Neßelrath Markus Dubielzig 《Universal Access in the Information Society》2013,12(1):73-87
This paper presents a new approach to make current and future television universally accessible. The proposed approach provides a means of universal accessibility both for remotely operating the TV set and for interacting with online services delivered through the TV. This proposal is based on the ISO/IEC 24752 “Universal Remote Console” (URC) standard. This standard defines an abstract user interface layer called the “user interface socket” and allows the development of pluggable (plug-in) user interfaces for any type of user and any control device. The proposed approach lays the foundation for the development of advanced user interfaces that can be interacted within various modalities. Different prototypes have been developed based on this approach and tested with end users. The user tests have shown this approach to be a viable option for the proposed scenarios. Based on the experience gathered with the prototypes, recommendations and implementation options are suggested for commercial adoption. 相似文献
27.
Salas E 《Human factors》2008,50(3):351-353
As the new century began, I took over as editor of the journal. By all accounts I inherited a robust journal - thanks to my predecessor. I made little adjustments on process and expanded the Editorial Board to reflect important emerging topics in human factors. The journal I "inherited" was in good shape, and I hope I left it a little better. In this paper, I reflect on the state of our science after making over 500 decisions over eight years (four as editor and four as associate editor). My reflections include issues concerning our theories, methodologies, and practice. These are offered as food for thought and in the hope that as we all reflect on the state of our science, we strive to make it better, more robust, and more relevant and that it has a greater influence on the world we live in. Time will tell. 相似文献
28.
This paper proposes a methodology to compute quadratic performance bounds when the closed loop poles of a discrete-time multivariable control loop are confined to a disk, centred at the origin, and with radius less than one. The underlying philosophy in this constraint is to avoid certain undesirable dynamic features which arise in quadratic optimal designs. An expression for the performance loss due to the pole location constraint is also provided. Using numerical examples, we show that the performance loss is compensated by an improved transient performance, specially visible in the control signals. 相似文献
29.
In this paper we consider the p-ary transitive reduction (TR
p
) problem where p>0 is an integer; for p=2 this problem arises in inferring a sparsest possible (biological) signal transduction network consistent with a set of
experimental observations with a goal to minimize false positive inferences even if risking false negatives. Special cases
of TR
p
have been investigated before in different contexts; the best previous results are as follows:
In this paper, our contributions are as follows:
R. Albert’s research was partly supported by a Sloan Research Fellowship in Science and Technology.
B. DasGupta’s research was partly supported by NSF grants DBI-0543365, IIS-0612044 and IIS-0346973.
E. Sontag’s research was partly supported by NSF grants EIA 0205116 and DMS-0504557. 相似文献
(1) | The minimum equivalent digraph problem, that correspond to a special case of TR1 with no critical edges, is known to be MAX-SNP-hard, admits a polynomial time algorithm with an approximation ratio of 1.617+ε for any constant ε>0 (Chiu and Liu in Sci. Sin. 4:1396–1400, 1965) and can be solved in linear time for directed acyclic graphs (Aho et al. in SIAM J. Comput. 1(2):131–137, 1972). |
(2) | A 2-approximation algorithm exists for TR1 (Frederickson and JàJà in SIAM J. Comput. 10(2):270–283, 1981; Khuller et al. in 19th Annual ACM-SIAM Symposium on Discrete Algorithms, pp. 937–938, 1999). |
• | We observe that TR p , for any integer p>0, can be solved in linear time for directed acyclic graphs using the ideas in Aho et al. (SIAM J. Comput. 1(2):131–137, 1972). |
• | We provide a 1.78-approximation for TR1 that improves the 2-approximation mentioned in (2) above. |
• | We provide a 2+o(1)-approximation for TR p on general graphs for any fixed prime p>1. |
30.
Classification of Fuzzy Mathematical Morphologies Based on Concepts of Inclusion Measure and Duality
Mathematical morphology was originally conceived as a set theoretic approach for the processing of binary images. Extensions
of classical binary morphology to gray-scale morphology include approaches based on fuzzy set theory. This paper discusses
and compares several well-known and new approaches towards gray-scale and fuzzy mathematical morphology. We show in particular
that a certain approach to fuzzy mathematical morphology ultimately depends on the choice of a fuzzy inclusion measure and
on a notion of duality. This fact gives rise to a clearly defined scheme for classifying fuzzy mathematical morphologies.
The umbra and the level set approach, an extension of the threshold approach to gray-scale mathematical morphology, can also
be embedded in this scheme since they can be identified with certain fuzzy approaches.
相似文献
Marcos Eduardo ValleEmail: |