全文获取类型
收费全文 | 235篇 |
免费 | 0篇 |
专业分类
化学工业 | 48篇 |
金属工艺 | 1篇 |
机械仪表 | 2篇 |
建筑科学 | 2篇 |
矿业工程 | 1篇 |
能源动力 | 2篇 |
轻工业 | 31篇 |
水利工程 | 3篇 |
无线电 | 5篇 |
一般工业技术 | 28篇 |
冶金工业 | 79篇 |
原子能技术 | 9篇 |
自动化技术 | 24篇 |
出版年
2022年 | 3篇 |
2021年 | 4篇 |
2015年 | 2篇 |
2014年 | 4篇 |
2013年 | 14篇 |
2012年 | 7篇 |
2011年 | 2篇 |
2010年 | 4篇 |
2009年 | 2篇 |
2008年 | 8篇 |
2007年 | 5篇 |
2006年 | 3篇 |
2005年 | 6篇 |
2004年 | 4篇 |
2003年 | 5篇 |
2002年 | 9篇 |
2001年 | 4篇 |
2000年 | 2篇 |
1999年 | 2篇 |
1998年 | 9篇 |
1997年 | 13篇 |
1996年 | 14篇 |
1995年 | 5篇 |
1994年 | 13篇 |
1993年 | 7篇 |
1992年 | 6篇 |
1991年 | 3篇 |
1990年 | 4篇 |
1989年 | 6篇 |
1988年 | 1篇 |
1987年 | 1篇 |
1986年 | 2篇 |
1985年 | 10篇 |
1984年 | 7篇 |
1983年 | 2篇 |
1982年 | 5篇 |
1981年 | 3篇 |
1980年 | 3篇 |
1979年 | 4篇 |
1978年 | 4篇 |
1977年 | 3篇 |
1976年 | 5篇 |
1975年 | 2篇 |
1974年 | 2篇 |
1973年 | 1篇 |
1972年 | 1篇 |
1971年 | 1篇 |
1970年 | 1篇 |
1969年 | 3篇 |
1968年 | 1篇 |
排序方式: 共有235条查询结果,搜索用时 0 毫秒
1.
2.
Making it easier for older people to talk to smart homes: the effect of early help prompts 总被引:1,自引:0,他引:1
K. Maria Wolters Klaus-Peter Engelbrecht Florian Gödde Sebastian Möller Anja Naumann Robert Schleicher 《Universal Access in the Information Society》2010,9(4):311-325
It is well known that help prompts shape how users talk to spoken dialogue systems. This study investigated the effect of
help prompt placement on older users’ interaction with a smart home interface. In the dynamic help condition, help was only
given in response to system errors; in the inherent help condition, it was also given at the start of each task. Fifteen older
and sixteen younger users interacted with a smart home system using two different scenarios. Each scenario consisted of several
tasks. The linguistic style users employed to communicate with the system (interaction style) was measured using the ratio of commands to the overall utterance length (keyword ratio) and the percentage of content
words in the user’s utterance that could be understood by the system (shared vocabulary). While the timing of help prompts
did not affect the interaction style of younger users, it was early task-specific help supported older users in adapting their
interaction style to the system’s capabilities. Well-placed help prompts can significantly increase the usability of spoken
dialogue systems for older people. 相似文献
3.
Charles A. Pittinger Jere S. Sellers Daniel C. Janzen Dianne G. Koch T. Michael Rothgeb Michael L. Hunnicutt 《Journal of the American Oil Chemists' Society》1993,70(1):1-15
Life-cycle inventories were compiled to characterize natural resource requirements and environmental emissions associated
with the sourcing and production of selected, detergent-grade surfactants and surfactant feedstocks. Petrochemical surfactant
types examined were linear alkylbenzene sulfonate, alcohol sulfate (AS), alcohol ethoxylate (AE) and alcohol ethoxylate sulfate
(AES). Oleochemical surfactants derived from palm oil, palm kernel oil and inedible tallow were AS, AE, AES and (for palm
oil and tallow) methyl ester sulfonate. It was determined that natural resource requirements were primarily related to the
source of feedstock and secondarily to surfactant type. Likewise, the composition and mass of atmospheric, aqueous and solid
emissions were principally determined by feedstock source. Energy requirements varied as a function of both feedstock and
surfactant type. The inventories do not support fundamental shifts in surfactant usage or feedstock sourcing on the basis
of environmental concerns, as no single surfactant or feedstock was identified as superior across all resource and emissions
criteria examined. The data provide baselines for evaluating opportunities for resource optimization, pollution prevention
and waste minimization within each production technology surveyed. 相似文献
4.
5.
Hans-Joachim Timpe Salah Ali Sven Ulrich Gerd Müller Klaus-Peter Kronfeld V. E. Zubarev 《Advanced Synthesis \u0026amp; Catalysis》1990,332(6):1013-1028
Photoinitiated Polymerization with Dialkoxy Thiocarbonyl Disulfides – a Polymerization Reaction with Primary Radical Termination The photoinduced free radical polymerization of methyl methacrylate (MMA) and some other vinyl monomers using dialkoxy thiocarbonyl disulfides ( 1 – 4 ) as photoinitiators was studied. The photolysis of these initiators leads to cleavage of the S S bond, which was determined by spin trapping experiments with phenyl tert-butyl nitrone. No evidence was found for a further thermal decomposition of the primary alkoxy thiocarbonyl sulfide radicals (R·) at room temperature. In the absence of scavengers the primary radicals react back exclusively to the initial compounds, due to a strong cage effect. By means of UV spectroscopic measurements and in the presence of MMA the quantum yields of the initiator decomposition were detected to be 0.8. The polymerization of acrylic and methacrylic derivatives can be initiated by the R·, contrary to the situation with fumarates and maleates. The mechanism of MMA polymerization depends on the light intensity absorbed by the initiators. At high intensities the combination of primary and polymer radicals terminates the chain reaction. This follows from the measured monomer exponent of α = 2, the light intensity exponent of β = 0,2 and the number of thiocarbonyl end groups of 2 in the polymers isolated. Contrary to this, in the low intensity region the experimental data obey the ideal kinetic equation. Kinetic modelling gives evidence for an interaction of the monomer with the cage radicals. 相似文献
6.
On the Use of Glyoxal Bis (t-Butyl Nitron) as a Spin Trap Nitroxides derived from glyoxal bis(t-butyl nitrone), GBBN , have been studied by e.s.r. spectroscopy. Well resolved e.s.r. spectra exhibiting extra hyperfine splitting by magnetic active nuclei in γ-position have been recorded for the spin adducts of alkyl, as well as .N3 and .CH2Cl radicals. Enhanced stability was found for the spin adducts of halogen atoms. However, a wider application of this spin trap is limited by the strong superposition of the e.s.r. signals of different radical spin adducts which is directly related to almost identical conformations of these nitroxides. 相似文献
7.
H.H. Janzen K.A. Beauchemin Y. Bruinsma C.A. Campbell R.L. Desjardins B.H. Ellert E.G. Smith 《Nutrient Cycling in Agroecosystems》2003,67(1):85-102
Agroecosystems rely on inputs of nitrogen (N) to sustain productivity. But added N can leak into adjacent environments, affecting the health of other ecosystems and their inhabitants. Worries about global warming have cast further attention on the N cycle in farmlands because farms are a main source of N2O, and because carbon sequestration, proposed to help reduce CO2 loads, requires a build-up of N. Our objective was to estimate, as an illustrative example, the net N balance of Canadian agroecosystems in 1996 and then infer some hypotheses about the routes of N loss, their magnitude, and ways of reducing them. We defined agroecosystems as all agricultural lands in Canada including soil to 1 m depth and all biota, except humans. Only net flows of N across those boundaries were counted in our balance – all others represent internal cycling. Based on our estimates, about 2.35 Tg N entered Canadian agroecosystems from biological fixation, fertilizers, and atmospheric deposition (excluding re-deposited NH3). In the same year, about 1.03 Tg N were exported in crop products and 0.19 Tg were exported in animals and animal products. Consequently, N inputs exceed exports in products by about 1.13 Tg, a surplus that is either accumulating in agroecosystems or lost to the environment. Because potential soil organic matter gains can account for only a small part of the surplus N, most is probably lost to air or groundwater. Our finding, that N losses amount to almost half of N added, concurs with field experiments that show crop recovery of added N in a given year is often not more than 60%. Better management may reduce the fraction lost somewhat but, because N in ecosystems eventually cycles back to N2, substantive gains in efficiency may not come easily. As well as trying to reduce losses, research might also focus on steering losses directly to N2, away from more harmful intermediates. If some of the `missing N' can be assimilated into organic matter, agricultural soils in Canada may need little added N to achieve C sequestration targets. 相似文献
8.
Tatyana Strekalova Dmitrii Pavlov Alexander Trofimov Daniel C. Anthony Andrei Svistunov Andrey Proshin Aleksei Umriukhin Alexei Lyundup Klaus-Peter Lesch Raymond Cespuglio 《International journal of molecular sciences》2022,23(4)
The phenomenon of individual variability in susceptibility/resilience to stress and depression, in which the hippocampus plays a pivotal role, is attracting increasing attention. We investigated the potential role of hippocampal cyclooxygenase-2 (COX-2), which regulates plasticity, neuroimmune function, and stress responses that are all linked to this risk dichotomy. We used a four-week-long chronic mild stress (CMS) paradigm, in which mice could be stratified according to their susceptibility/resilience to anhedonia, a key feature of depression, to investigate hippocampal expression of COX-2, a marker of microglial activation Iba-1, and the proliferation marker Ki67. Rat exposure, social defeat, restraints, and tail suspension were used as stressors. We compared the effects of treatment with either the selective COX-2 inhibitor celecoxib (30 mg/kg/day) or citalopram (15 mg/kg/day). For the celecoxib and vehicle-treated mice, the Porsolt test was used. Anhedonic (susceptible) but not non-anhedonic (resilient) animals exhibited elevated COX-2 mRNA levels, increased numbers of COX-2 and Iba-1-positive cells in the dentate gyrus and the CA1 area, and decreased numbers of Ki67-positive cells in the subgranular zone of the hippocampus. Drug treatment decreased the percentage of anhedonic mice, normalized swimming activity, reduced behavioral despair, and improved conditioned fear memory. Hippocampal over-expression of COX-2 is associated with susceptibility to stress-induced anhedonia, and its pharmacological inhibition with celecoxib has antidepressant effects that are similar in size to those of citalopram. 相似文献
9.
Thomas Janzen 《History of Photography》2013,37(3):182-186
Abstract In photography, one should surely proceed from the essence of the object and attempt to represent it through purely photographic means, regardless of whether it is a human being, a landscape, architecture or something else; whereas today a rape of the object for the sake of formal play is more often the norm. Because the German word Sachlichkeit has taken on practically the opposite meaning today, I have to use a foreign word to properly characterize the position of servitude I maintain before the motif: ‘objectivity’.1 相似文献
10.
This paper presents an efficient optimal control and recursive dynamics-based computer animation system for simulating and controlling themotion of articulated figures. A quasi-Newton nonlinear programmingtechnique (super-linear convergence) is implemented to solve minimumtorque-based human motion-planning problems. The explicit analyticalgradients needed in the dynamics are derived using a matrix exponentialformulation and Lie algebra. Cubic spline functions are used to make thesearch space for an optimal solution finite. Based on our formulations,our method is well conditioned and robust, in addition to beingcomputationally efficient. To better illustrate the efficiency of ourmethod, we present results of natural looking and physically correcthuman motions for a variety of human motion tasks involving open andclosed loop kinematic chains. 相似文献