全文获取类型
收费全文 | 1359篇 |
免费 | 65篇 |
国内免费 | 4篇 |
专业分类
电工技术 | 24篇 |
化学工业 | 293篇 |
金属工艺 | 23篇 |
机械仪表 | 25篇 |
建筑科学 | 68篇 |
矿业工程 | 15篇 |
能源动力 | 56篇 |
轻工业 | 165篇 |
水利工程 | 12篇 |
石油天然气 | 4篇 |
无线电 | 62篇 |
一般工业技术 | 146篇 |
冶金工业 | 392篇 |
原子能技术 | 8篇 |
自动化技术 | 135篇 |
出版年
2023年 | 10篇 |
2022年 | 19篇 |
2021年 | 24篇 |
2020年 | 19篇 |
2019年 | 36篇 |
2018年 | 29篇 |
2017年 | 32篇 |
2016年 | 35篇 |
2015年 | 22篇 |
2014年 | 42篇 |
2013年 | 83篇 |
2012年 | 48篇 |
2011年 | 55篇 |
2010年 | 44篇 |
2009年 | 48篇 |
2008年 | 47篇 |
2007年 | 46篇 |
2006年 | 44篇 |
2005年 | 38篇 |
2004年 | 29篇 |
2003年 | 26篇 |
2002年 | 31篇 |
2001年 | 19篇 |
2000年 | 23篇 |
1999年 | 34篇 |
1998年 | 57篇 |
1997年 | 32篇 |
1996年 | 27篇 |
1995年 | 20篇 |
1994年 | 15篇 |
1993年 | 18篇 |
1992年 | 9篇 |
1991年 | 21篇 |
1990年 | 20篇 |
1989年 | 14篇 |
1988年 | 10篇 |
1987年 | 13篇 |
1986年 | 15篇 |
1985年 | 12篇 |
1984年 | 11篇 |
1982年 | 14篇 |
1981年 | 14篇 |
1980年 | 21篇 |
1979年 | 18篇 |
1978年 | 9篇 |
1977年 | 14篇 |
1976年 | 13篇 |
1975年 | 15篇 |
1974年 | 15篇 |
1957年 | 9篇 |
排序方式: 共有1428条查询结果,搜索用时 15 毫秒
31.
32.
33.
Shen Lang Poudel Nirakar Gibson George N. Hou Bingya Chen Jihan Shi Haotian Guignon Ernest Page William D. Pilar Arturo Cronin Stephen B. 《Nano Research》2018,11(4):2310-2314
Nano Research - We report plasmon resonant excitation of hot electrons in a photodetector based on a metal/oxide/metal (Au/Al2O3/graphene) heterostructure. In this device, hot electrons, excited... 相似文献
34.
35.
Jorge E. Mendoza Bruno Castanier Christelle Guéret Andrés L. Medaglia Nubia Velasco 《Computers & Operations Research》2010,37(11):1886-1898
The multi-compartment vehicle routing problem (MC-VRP) consists of designing transportation routes to satisfy the demands of a set of customers for several products that, because of incompatibility constraints, must be loaded in independent vehicle compartments. Despite its wide practical applicability the MC-VRP has not received much attention in the literature, and the few existing methods assume perfect knowledge of the customer demands, regardless of their stochastic nature. This paper extends the MC-VRP by introducing uncertainty on what it is known as the MC-VRP with stochastic demands (MC-VRPSD). The MC-VRPSD is modeled as a stochastic program with recourse and solved by means of a memetic algorithm. The proposed memetic algorithm couples genetic operators and local search procedures proven to be effective on deterministic routing problems with a novel individual evaluation and reparation strategy that accounts for the stochastic nature of the problem. The algorithm was tested on instances of up to 484 customers, and its results were compared to those obtained by a savings-based heuristic and a memetic algorithm (MA/SCS) for the MC-VRP that uses a spare capacity strategy to handle demand fluctuations. In addition to effectively solve the MC-VRPSD, the proposed MA/SCS also improved 14 best known solutions in a 40-problem testbed for the MC-VRP. 相似文献
36.
This paper investigates the fundamental difference between a simple e-tender box and a traditional physical tender box, and
highlights a series of security traps created by the functional differences. Based on our findings, we have defined the security
requirements for an e-tender submission protocol. We also discuss functional limitations of cryptographic technologies. As
a result, two secure e-tender submission protocols are proposed which enable a secure e-tender submission. Protocols are assumed
to run under the condition that all tendering parties (principal and tenderers) are dishonest players. Our informal and formal
security analysis show that these protocols meet their security goals under well known collusion scenarios. Because security
is a process not a product, our approach will have broad industry application for developing secure electronic business processes
in areas other than e-tendering.
相似文献
Colin BoydEmail: |
37.
Dolors Costal Cristina Gómez Anna Queralt Ruth Raventós Ernest Teniente 《Software and Systems Modeling》2008,7(4):469-486
An important aspect in the specification of conceptual schemas is the definition of general constraints that cannot be expressed
by the predefined constructs provided by conceptual modeling languages. This is generally achieved by using general-purpose
languages like OCL. In this paper we propose a new approach that facilitates the definition of such general constraints in
UML. More precisely, we define a profile that extends the set of predefined UML constraints by adding certain types of constraints
that are commonly used in conceptual schemas. We also show how our proposal facilitates reasoning about the constraints and
their automatic code generation, study the application of our ideas to the specification of two real-life applications, and
present a prototype tool implementation.
相似文献
Ernest TenienteEmail: |
38.
Hilgard Ernest R.; Morgan Arlene H.; Macdonald Hugh 《Canadian Metallurgical Quarterly》1975,84(3):280
To test whether pain blocked by hypnotic analgesia may still be perceived at some level, 20 highly hypnotizable undergraduates participated in an experiment involving cold pressor pain in the normal condition and in hypnotically suggested analgesia. 3 reports were obtained reflecting felt pain within the hypnotic analgesia condition: the usual verbal report on a numerical scale, a manual report by "automatic key pressing," and a retrospective verbal report through "automatic talking." 9 Ss who were amnesic for both keypressing and automatic talking reported more pain in the automatic (hidden) reports than in their usual verbal reports. 8 of these 9, following release of amnesia, had a clear perception of 2 levels of awareness of the pain: the usual hypnotic experience of pain attenuated by analgesia suggestions, and a knowledge at another level of a more severe pain. In no case, however, did an S give a retrospective report of normal suffering at this "hidden" level. The hypnotically analgesic S may have reported no pain verbally because he was amnesic for it; when amnesia was removed he recalled the sensory pain, but without a suffering component, because suffering apparently did not occur. (24 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
39.
Christian Daul Pierre Graebling Ernest Hirsch 《Computer Vision and Image Understanding》1998,72(3):215-236
The edges of simple geometrical (e.g., manufactured) parts can generally be approximated sufficiently accurately by straight-line segments and elliptical arcs in order, for example, to carry out a dimensional analysis of these parts, such as required by inspection tasks. Hough transforms are robust methods for the detection of straight-line segments but are not directly suitable for the detection of elliptical arcs, for which the processing time and memory space necessary are too important. We present in this paper a new method which allows the determination of the parameters of elliptical arcs (or of ellipses) by use of a two-dimensional discretized parameter space defined similarly to the usual Hough space. This new method allows both the detection and characterization of ellipses whose major and minor axis lengths can be as small as four pixels long or of elliptical arcs with a small angular aperture. 相似文献
40.