全文获取类型
收费全文 | 2332篇 |
免费 | 74篇 |
国内免费 | 3篇 |
专业分类
电工技术 | 57篇 |
综合类 | 9篇 |
化学工业 | 569篇 |
金属工艺 | 53篇 |
机械仪表 | 66篇 |
建筑科学 | 56篇 |
矿业工程 | 10篇 |
能源动力 | 52篇 |
轻工业 | 293篇 |
水利工程 | 20篇 |
石油天然气 | 7篇 |
无线电 | 147篇 |
一般工业技术 | 324篇 |
冶金工业 | 328篇 |
原子能技术 | 36篇 |
自动化技术 | 382篇 |
出版年
2022年 | 15篇 |
2021年 | 44篇 |
2020年 | 23篇 |
2019年 | 31篇 |
2018年 | 28篇 |
2017年 | 45篇 |
2016年 | 72篇 |
2015年 | 41篇 |
2014年 | 69篇 |
2013年 | 122篇 |
2012年 | 99篇 |
2011年 | 113篇 |
2010年 | 89篇 |
2009年 | 107篇 |
2008年 | 100篇 |
2007年 | 94篇 |
2006年 | 62篇 |
2005年 | 58篇 |
2004年 | 58篇 |
2003年 | 53篇 |
2002年 | 65篇 |
2001年 | 45篇 |
2000年 | 42篇 |
1999年 | 41篇 |
1998年 | 76篇 |
1997年 | 55篇 |
1996年 | 45篇 |
1995年 | 38篇 |
1994年 | 32篇 |
1993年 | 45篇 |
1992年 | 31篇 |
1991年 | 22篇 |
1990年 | 20篇 |
1989年 | 20篇 |
1988年 | 19篇 |
1987年 | 20篇 |
1986年 | 16篇 |
1985年 | 25篇 |
1984年 | 23篇 |
1983年 | 27篇 |
1982年 | 19篇 |
1981年 | 20篇 |
1980年 | 20篇 |
1979年 | 32篇 |
1978年 | 25篇 |
1977年 | 21篇 |
1976年 | 20篇 |
1975年 | 22篇 |
1974年 | 28篇 |
1973年 | 16篇 |
排序方式: 共有2409条查询结果,搜索用时 46 毫秒
51.
Johann Füller Kurt Matzler Katja Hutter Julia Hautz 《Creativity & Innovation Management》2012,21(3):247-262
Virtual customer integration and open innovation are considered as appropriate means to improve the success of new product development. However, only when consumers are qualified and motivated to contribute promising ideas and relevant know‐how they are able to add value to a producer's innovation process. In this study, we explore the symmetric and asymmetric impact of various creativity components on consumers' idea generation, concept development, or prototype building abilities as well as interest in co‐creation projects. Our results show that creativity components are of different importance. While some characteristics are needed above certain thresholds to successfully accomplish a certain development task, exceeding those does not necessarily lead to better outputs. Other characteristics improve the creative output only if they exceed specific levels. 相似文献
52.
Confining a binary mixture, one can profoundly alter its miscibility behavior. The qualitative features of miscibility in confined geometry are ratheruniversal and shared by polymer mixtures as well as small molecules, but the unmixing transition in the bulk and the wetting transition are typically well separated in polymer blends. The interplay between wetting and miscibility of a symmetric polymer mixture via large-scale Monte Carlo simulations in the framework of the bond fluctuation model and via numerical self–consistent field calculations is studied. The film surfaces interact with the monomers via short ranged potentials, and the wetting transition of the semi–infinite system is of first order. It can be accurately located in the simulations by measuring the surface and interface tensions and using Young’s equation. If both surfaces in a film attract the same component, capillary condensation occurs and the critical point is close to the critical point of the bulk. If surfaces attract different components, an interface localization/delocalization occurs which gives rise to phase diagrams with two critical points in the vicinity of the pre-wetting critical point of the semi–infinite system. The crossover between these two types of phase diagrams as a function of the surface field asymmetry is studied. The dependence of the phase diagram on the film thickness Δ for antisymmetric surface fields is investigated. Upon decreasing the film thickness, the two critical points approach the symmetry axis of the phase diagram, and below a certain thickness Δtri, there remains only a single critical point at the symmetric composition. This corresponds to a second-order interface localization/delocalization transition even though the wetting transition is of first order. At a specific film thickness, Δtri, tricritical behavior is found. The behavior of antisymmetric films is compared with the phase behavior in an antisymmetric double wedge. While the former is the analog of the wetting transition of a planar surface, the latter is related to the filling behavior of a single wedge. Evidence for a second-order interface localization/delocalization transition in an antisymmetric double wedge is presented, and its unconventional critical behavior is related to the predictions of Parry et al. (Phys. Rev. Lett. 83:5535 (1999)) for wedge filling. The critical behavior differs from the Ising universality class and is characterized by strong anisotropic fluctuations.Invited paper presented at the Fifteenth Symposium on Thermophysical Properties, June 022–27, 2003, Boulder, Colorado, U.S.A. 相似文献
53.
Wall Jacqueline Remondet; Busch Monique; Koch Steven M.; Alexander Gina; Minnich Heike; Jackson-Walker Susan 《Canadian Metallurgical Quarterly》2005,2(1):39
Questions are often raised regarding the effectiveness and value of treatment programs for children and families. Recently, programs have been increasingly held accountable for services offered. In response, the member agencies of IARCCA have developed a comprehensive outcome measurement program. This article describes the project, focusing on the conditions that led to its inception and how the measurement plan was developed. In addition, the article includes information on the selection of personnel, measurement instruments, and methods and on the process of data collection. Summary results are provided, including how these results are utilized to improve services. Finally, the continued expansion and future directions of the Outcome Project are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
54.
A Simulation Framework for Heterogeneous Agents 总被引:2,自引:0,他引:2
David Meyer Alexandros Karatzoglou Friedrich Leisch Christian Buchta Kurt Hornik 《Computational Economics》2003,22(2-3):285-301
We introduce a generic simulation framework suitable for agent-based simulations featuring the support of heterogeneous agents, hierarchical scheduling, and flexible specification of design parameters. One key aspect of this framework is the design specification: we use a format based on the Extendible Markup Language (XML) that is simple-structured yet still enables the design of flexible models. Another issue in agent-based simulations, especially when ready-made components are used, is the heterogeneity arising from both the agents' implementations and the underlying platforms. To tackle such obstacles, we introduce a wrapper technique for mapping the functionality of agents living in an interpreter-based environment to a standardized JAVA interface, thus facilitating the task for any control mechanism (like a simulation manager) because it has to handle only one set of commands for all agents involved. Again, this mapping is made by an XML-based definition format. We demonstrate the technique by applying it to a simple sample simulation of two mass marketing firms operating in an artificial consumer environment. 相似文献
55.
Simulation of thermally induced package effects with regard to piezoresistive pressure sensors 总被引:1,自引:0,他引:1
Frank Schilling Werner Langheinrich Kurt Weiblen Dieter Arand 《Sensors and actuators. A, Physical》1997,60(1-3):37-39
Microsystems are on their way out of laboratories into production. One of these microsystems, a piezoresistive pressure sensor developed by Robert Bosch GmbH, is examined within this paper. Obviously, one can detect undesirable temperature effects resulting from the sensor package, which influence the electrical characteristics of the sensor. By means of finite-element modelling (FEM), a simulation of the temperature effects can be managed. It is also possible to search for alternative designs of the sensor package. 相似文献
56.
Gadolinium-enhanced magnetic resonance angiography of the pelvis in patients with erectile impotence
Michael K. Stehling Libin Liu Gerhard Laub Kurt Fleischmann Ulrike Rohde 《Magma (New York, N.Y.)》1997,5(3):247-254
This study evaluted the potential of contrast-enhanced digital-subtraction magnetic resonance angiography (CE-DS-MRA) for
noninvasive angiographic delineation of the arterial supply of the penis in patients with erectile dysfunction. After induction
of an erection with prostaglandin E, a three-dimensional fast imaging with steady-state precision (FISP) sequence with TE
of 1.8–2 milliseconds, TR of 4.4–5 milliseconds, and flip angle of 40°–60° was used to obtain high-resolution angiograms of
the pelvis and penis during the injection of gadolinium diethylenetriaminepentaacetic acid (Gd-DTPA) 0.3 mmol/kg body weight,
within 30–50 seconds. DS maximum intensity projections (MIPs) and multiplanar reconstructions (MPRs) were compared with clinical
work-up and directional Doppler ultrasound in 11 patients. In all 11 patients (100%), the arterial supply of the penis could
be delineated from the aortic bifurcation via the iliac and internal pudendal arteries to the dorsal and deep penile arteries.
Of the 22 internal pudendal arteries, 6 (27%) were occluded on CE-DS-MRA and 5 (23%) had stenoses, of which 4 (18%) were greater
than 50%. In 7 patients (64%) good correlation between CE-DS-MRA and clinical findings and/or Doppler ultrasound was found;
in 2 patients (18%), the correlation was moderate, and in 2 patients (18%) results were discrepant. In 6 patients (55%), MRA
provided additional information to the clinical and Doppler ultrasound work-up. CE-DS-MRA can delineate small sessels such
as the internal pudendal and penile arteries and thus has the potential to become a noninvasive angiography method in the
work-up of erectile impotence.
Supported by Siemens Medical Systems, Erlangen; Schering AG, Berlin; and Agfa-Gevaert AG, Leverkusen. 相似文献
57.
58.
Eric N. Hanson I.-Cheng Chen Roxana Dastur Kurt Engel Vijay Ramaswamy Wendy Tan Chun Xu 《The VLDB Journal The International Journal on Very Large Data Bases》1998,7(1):12-24
A software architecture is presented that allows client application programs to interact with a DBMS server in a flexible
and powerful way, using either direct, volatile messages, or messages sent via recoverable queues. Normal requests from clients
to the server and replies from the server to clients can be transmitted using direct or recoverable messages. In addition,
an application event notification mechanism is provided, whereby client applications running anywhere on the network can register
for events, and when those events are raised, the clients are notified. A novel parameter passing mechanism allows a set of
tuples to be included in an event notification. The event mechanism is particularly useful in an active DBMS, where events
can be raised by triggers to signal running application programs.
Received July 21, 1995 / Accepted May 30, 1996 相似文献
59.
60.
The Why2-Atlas tutoring system presents students with qualitative physics questions and encourages them to explain their answers through natural language. Although there are inexpensive techniques for analyzing explanations, we claim that better understanding is necessary for use within tutoring systems. In this paper we motivate and describe how the system creates and uses a deeper proof-based representation of student essays in order to provide students with substantive feedback on their explanations. We describe in detail the abductive reasoner, Tacitus-lite+, that we use within the tutoring system. We also discuss evaluation results for an early version of the Why2-Atlas system and a subsequent evaluation of the theorem-proving module. We conclude with the discussion of work in progress and additional future work for deriving more benefits from a proof-based approach for tutoring applications. 相似文献