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181.
The blood concentration of 1,8-cineole and its metabolites was measured in six male brushtail possums while they voluntarily
fed on diets laced with varying concentrations of cineole for 3 d. On the third day, blood samples were collected during and
after each bout of feeding for 3 hr. Blood cineole was measured by using headspace solid-phase microextraction (SPME), while
cineole metabolites were measured by liquid–liquid extraction followed by gas chromatography-mass spectroscopy. Feeding patterns
were measured by continual recording of residual food weight and time. Cineole absorption was rapid, resulting in a peak blood
concentration at the end of each feeding bout. The blood concentration of cineole did not exceed a critical value (51.8 ±
14.1 μmol/l) regardless of the concentration in the diet. Food and, therefore, cineole intake was regulated. The amount of
food ingested in the first feeding bout decreased from 236 ± 52 g on the control diet to 36 ± 20 g on the 4% cineole diet.
The amount of cineole ingested in the first bout (1.18 ± 1.10 g) was the same regardless of the dietary concentration and
was controlled by the size of the meal. Total food eaten during the 7-hr feeding session decreased by 64% from 368 ± 94 g
(control diet) to 131 ± 52 g (4% diet). Total cineole intake increased from 2.47 ± 0.60 g (1% diet) to 5.05 ± 2.41 g (4% diet).
Cineole metabolites accumulated throughout the sampling period and were generally still rising at the end of blood sampling
period. Blood levels of metabolites were at least 10-fold higher than cineole levels. The immediate control of feeding seems
to be regulated by blood levels of cineole, whereas metabolites are likely to be more important in regulating the chronic
ingestion of cineole. 相似文献
182.
Landell-Mills N 《Philosophical transactions. Series A, Mathematical, physical, and engineering sciences》2002,360(1797):1817-1825
Market-based approaches to environmental management are all the rage. Claims that market mechanisms can encourage environmental protection and promote greater economic efficiency while saving taxpayers' money are tantalizing. In the forestry sector, policy makers are widely heeding this advice and shrinking command-and-control systems in favour of incentive mechanisms that seek to align private enthusiasm with the public good. In some cases, governments are even promoting the creation of markets where none existed before. In others, markets are evolving of their own accord. In such times of change, it is difficult to stand back and take stock. Yet, it is during such times that guidance is most needed. In the rush to introduce market-based solutions to environmental problems, a particular concern is how markets are impacting on the poor. In this paper an effort is made to draw on a recent review of markets for four forest environmental services (biodiversity conservation, carbon sequestration, watershed protection and landscape beauty) to draw out preliminary insights into how markets are performing with respect to their impacts on the poor. The evidence suggests a need for caution. While the potential benefits are significant, the poor face an uphill battle in realizing them. Key constraints facing the poor include a lack of property rights over forest resources and their environmental services; inadequate skills and education; poor market information; lack of market contacts; inadequate communication infrastructure; inappropriate contract design; and lack of access to financial resources. To tackle these, four potential ways forward are highlighted: (1) assign property rights to forest assets and their related environmental services in ways that respect customary arrangements and poor people's tenure; (2) strengthen capacity for market participation, e.g. through training and education; (3) invest in the provision of market information, advice and, essentially, a contact point for buyers and sellers, perhaps through the establishment of a 'market support centre'; and (4) improve access to finance so that poor individuals can make necessary up-front investments in market participation. 相似文献
183.
Empirically based item selection guidelines are presented for moving the cut score on equated tests consisting of n dichotomous items calibrated assuming the Rasch model. The cut score on a test form B, c(B), may be made higher than test form A's cut score, c(A), in the following ways: (1) select items for test form B such that the variance of test form B's item difficulties, sigma(2)(B), will be equal to test form A's sigma(2)(A), but test form B's mean item difficulty, mu(B), will be less that of test form A, mu(A); (2) given c(A) > n/2, select items for test form B such that mu(B) s(2)(A). To make c(B) lower than c(A), the direction of the changes listed above for the two tests item difficulties sigma(2) and mu should be reversed. Derivations of lemmas that underlie the guidelines are provided as well as a simulated example. 相似文献
184.
The effect of the microstructure of tin-doped indium oxide (ITO) films on their electrochemical performance was studied using three redox probes, tris(2,2'-bipyridyl ruthenium(II) chloride (Ru(bpy)3(2+/3+)), ferrocyanide (Fe(CN)6(4-/3-)), and ferrocenemethanol (FcCH2H(0/+)). ITO films were deposited using dc magnetron sputtering under a variety of conditions that resulted in films having different degrees of crystallinity, crystallographic texture, sheet resistance, surface roughness, and percent tin. It was found that the electron transfer for all three redox probes used in this study was more efficient at polycrystalline films than at amorphous ITO films. This effect is more pronounced at faster scan rates. The crystallographic texture of the ITO films, surface roughness, and a change in sheet resistance from 7.9 to 13.7 ohms/square did not have an effect on electron-transfer kinetics. ITO films deposited using a 1 wt % SnO2 target and having sheet resistance comparable to films deposited using a 10 wt % SnO2 target had dramatically different microstructure from the films with higher weight percent Sn and were shown to perform poorly when used as electrode materials. We believe that the dramatic differences in electron-transfer kinetics observed at the various ITO films can be attributed to either the different density of defect sites along the grain boundaries or defect sites caused by substitutional Sn in the film. 相似文献
185.
A Modal Perspective on Path Constraints 总被引:2,自引:0,他引:2
Alechina Natasha; Demri Stephane; de Rijke Maarten 《Journal of Logic and Computation》2003,13(6):939-956
186.
Orr Scott P.; Lasko Natasha B.; Shalev Arieh Y.; Pitman Roger K. 《Canadian Metallurgical Quarterly》1995,104(1):75
The authors evaluated eyeblink and autonomic components of the acoustic startle response in combat-related posttraumatic stress disorder (PTSD). Thirty-seven Vietnam combat veterans with current PTSD and 19 combat veterans without PTSD were exposed to 15 consecutive 95-dB, 500-ms, 1000-Hz tones with 0-ms rise and fall times, while orbicularis oculi electromyogram, skin conductance, and heart rate responses were measured. PTSD veterans produced larger averaged electromyographic and heart rate responses, and a slower decline in skin conductance responses, across the 15 tone presentations compared to non-PTSD veterans. Results of this study provide laboratory support for an exaggerated startle response in PTSD and replicate and extend previous findings of increased autonomic responses to loud tone stimuli in this disorder. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
187.
Daniel Kroening Natasha Sharygina Stefano Tonetta Aliaksei Tsitovich Christoph M. Wintersteiger 《Formal Methods in System Design》2013,42(3):221-261
This paper presents algorithms for program abstraction based on the principle of loop summarization, which, unlike traditional program approximation approaches (e.g., abstract interpretation), does not employ iterative fixpoint computation, but instead computes symbolic abstract transformers with respect to a set of abstract domains. This allows for an effective exploitation of problem-specific abstract domains for summarization and, as a consequence, the precision of an abstract model may be tailored to specific verification needs. Furthermore, we extend the concept of loop summarization to incorporate relational abstract domains to enable the discovery of transition invariants, which are subsequently used to prove termination of programs. Well-foundedness of the discovered transition invariants is ensured either by a separate decision procedure call or by using abstract domains that are well-founded by construction. We experimentally evaluate several abstract domains related to memory operations to detect buffer overflow problems. Also, our light-weight termination analysis is demonstrated to be effective on a wide range of benchmarks, including OS device drivers. 相似文献
188.
Dr. Hanna Krasnova Natasha F. Veltri Klaus Spengler Prof. Oliver Günther 《WIRTSCHAFTSINFORMATIK》2013,55(3):159-173
“Deal of the Day” (DoD) platforms have quickly become popular by offering savings on local services, products and vacations. For merchants, these platforms represent a new marketing channel to advertise their products and services and attract new customers. DoD platform providers, however, struggle to maintaining a stable market share and profitability, because entry and switching costs are low. To sustain a competitive market position, DoD providers are looking for ways to build a loyal customer base. However, research examining the determinants of user loyalty in this novel context is scarce. To fill this gap, this study employs Grounded Theory methodology to develop a conceptual model of customer loyalty to a DoD provider. In the next step, qualitative insights are enriched and validated using quantitative data obtained in a survey with 202 DoD users. We find that customer loyalty is in large part driven by monetary incentives, but can be eroded if impressions from merchant encounter are below expectations. In addition, enhancing the share of deals relevant for consumers, i.e. signal-to-noise ratio, and mitigating perceived risks of a transaction emerge as challenges. Beyond theoretical value, our results offer practical insights into how customer loyalty to a DoD provider can be promoted. 相似文献
189.
OBJECTIVE: This study examined the effect of two in-vehicle information systems (IVIS) on signal detection in the visual, auditory, and tactile modalities; established whether the detrimental effects of an IVIS on driving could be quantified by these detection tasks; and examined the effect of stimulus modality on signal detection. BACKGROUND: The peripheral detection task has been used widely for assessing the effects of an IVIS on driving. However, performance on this task relies on drivers' ability to see a series of LEDs, which can be problematic in field tests (e.g., on sunny days). METHOD: Participants responded to one of three detection tasks during a simulated driving experiment. The effect of IVIS interaction on these detection tasks was also measured. Reduced performance in the detection tasks was assumed to indicate a decline in drivers' ability to handle sudden events in the driving task. RESULTS: Response time to all detection tasks increased by around 200 ms when drivers performed the IVIS tasks, as compared with baseline driving. Analyses of variance and comparison of effect sizes showed the effects of these two IVISs to be the same across the three detection tasks. CONCLUSION: These detection tasks are useful for quantifying the safety of an IVIS during driving. The absence of a difference in signal detection by modality suggests that performance on these tasks relies on general attentional resources and is not modality specific. APPLICATION: The signal detection tasks employed here should be further investigated for their suitability in assessing the safety of in-vehicle systems. 相似文献
190.
Richard D. Johnson Natasha F. Veltri Steven Hornik 《International journal of human-computer interaction》2013,29(6):595-612
This study examined how social cues in an interface and user gender affected attributions of responsibility for the process and outcomes of interacting with a computer. Using a 2 × 2 between-subjects laboratory design, 391 participants were randomly assigned to work with a computer that utilized either a traditional interface or an interface designed to include higher social cues. The results of this study indicated that those who interacted with the interface with greater social cues made greater attributions of responsibility to the computer. In addition, women were more likely to ascribe responsibility to the computer. Results did not support an interaction between gender and interface design. Implications for theory and practice are discussed. 相似文献