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31.
Three experiments investigated procedures derived from research on knowledge acquisition, group processes, and artificial intelligence for facilitating the development of expertise. In each experimental session, subjects learned to control a simulated sugar production factory. Then they formulated written policies for controlling sugar production either alone as individuals or in small groups. An adaptive AI system provided feedback on policy quality. The research also investigated the use of forced reflective practice in which learners attempted to predict what their policy would do while performing the task. The AI system provided feedback about what their policy would have done in each situation and the outcome based on their policy's response or their suggested alternative response. Results indicated that group interaction and feedback from the AI system improved policy quality. However, only when all three procedures were employed, group interaction, AI feedback, and forced reflective practice, was the development of individual expertise on the task enhanced.  相似文献   
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33.
Consultants, in competing for work through two-envelope fee tendering, have been urged to consider variability differences between fees and technical scores, since the criterion with the greatest variability will influence which consultant is awarded the contract. Fee and technical score variability arising from different client fee tendering competitions is analysed in this paper, and a method proposed for determining whether a particular client's two-envelope fee tendering competition is likely to be dominated in terms of technical score or fee. Such information should be useful to consultants, as part of their bidding strategy, in deciding whether to aim for a higher technical score or submit a lower fee. Standard deviation is used to measure fee and technical score variability. Fee and technical score standard deviations are determined for each tendering competition, expressed as a ratio and aggregated over a series of competitions. A technical score-fee standard deviation ratio approximately equal to unity indicates that for future competitions consultants should adopt a balanced bidding strategy in putting equal emphasis on fee and technical score. A smaller ratio indicates that consultants should adopt a ‘low fee’ strategy whereas a larger ratio shows that consultants should adopt a ‘high technical score’ strategy. Fee tendering data from two large Hong Kong public sector clients were analysed. Fees were found to dominate the vast majority of tendering competitions, thereby indicating that consultants would be wise to adopt a low fee strategy in future competitions.  相似文献   
34.
This paper offers a new perspective to explain how and why the U.S. federal government pursued a policy agenda that from the early-1990s promoted homeownership as the preferred housing tenure of choice for low-income households. Using policy design theory (Schneider &; Ingram 1997 Schneider, A. L. and Ingram, H. M. 1997. Policy Design for Democracy, Lawrence, KS: University Press of Kansas.  [Google Scholar]), this paper argues that the social constructions of homeownership, low-income households, and the private mortgage industry were instrumental in the development of policies to increase low-income homeownership. The benefits associated with homeownership, based on long-standing norms around success, stability, and the American Dream, justified government interventions to increase access to private mortgage markets for low-income households. This policy stance, however, did nothing to assist households with maintaining homeownership for the long term. The social constructions embedded in the rationales and implementation of these policies contributed to their failure to sustain homeownership and realize its benefits for low-income homeowners.  相似文献   
35.
Ordered microporous carbons containing dispersed platinum nanoparticles were fabricated and chosen as suitable models to investigate micro-structure development and hydrogen transport properties of zeolite-templated carbons. X-ray photoelectron spectroscopy analysis revealed that the enhanced heat of adsorption is related to the narrow micro-channels templated from the zeolite and the presence of certain CO groups on the carbon. The lack of a well-defined and intense rotational transition line and the persistent broad H2 recoil spectrum in neutron scattering results suggests a distribution of binding sites. Most interestingly, hydrogen diffusion occurs on two time scales, consisting of a fast liquid-like jump diffusion on the timescale of picoseconds along with an even faster bulk-like diffusion. The liquid-like motion is characterized by a diffusion constant of (2.1 ± 0.3) × 10−8 m2/s with an activation energy of ca. 77 K; both values indicate somewhat lower mobility than similar dynamics of H2 on nanotubes, activated carbon XC-72, or Grafoil, yet greater mobility than that of bulk liquid. These unusual characteristics for hydrogen in carbons are believed to arise from the network of narrow pores in this zeolite-templated image of the zeolite. In fact, the diffusion constants of the templated carbons are extremely similar to those measured for zeolite 13X.  相似文献   
36.
Sections of venison loins (LD) weighing approximately 300 g from 12 red deer (Cervus elaphus) were packaged using four packaging methods: (a) vacuum packaging, (b) CO2 flushed using a nylon containment film (CO2-Nylon), (c) CO2 flushed using an ultra-high barrier containment film (CO2-UHB), and (d) CO2 flushed using an aluminium foil laminate containment film (CO2-Foil) and stored for 1, 6, 12 and 18 weeks at 0°C. Meat pH values were lower in all CO2 flushed meat packages (P<0·05) than in vacuum packaged meat. Lactic acid bacteria and total anaerobic counts increased over storage time in all packages regardless of treatment up to values of log10 7·8 and 7·6 g−1, respectively. Tenderness tended to increase as meat was stored for up to 18 weeks. Colour scores taken during simulated retail display indicated that colour deteriorated more rapidly when meat was stored for 12 and 18 weeks than for 1 and 6 weeks. Vacuum packaging and gas flushing (CO2-Foil) resulted in higher initial colour scores than venison packaged in the CO2-Nylon or CO2-UHB materials. Venison stored for 18 weeks also exhibited a higher proportion of packages containing off odours, lower flavour desirability and flavour intensity scores as well as higher off flavour scores than meat stored for shorter times. The implications of these effects are discussed. Although there were few significant differences in microbial growth and sensory characteristics due to packaging method or containment film, vacuum packaging appeared to be the most economic and produced meat of better colour stability.  相似文献   
37.
An analysis of dilute, turbulent particle/liquid two-phase flow is presented. The three-dimensional conservation equations that govern turbulent motion in solid/fluid flows are derived using ensemble averaging, and the unknown terms in these equations are constituted to achieve closure. These closure terms include the shear stress due to interparticle collisions, the corresponding terms in the Reynolds stress equation, the force and dissipation due to particle-wall collisions, and the interfacial work due to particle/turbulent eddy interaction. The resultant two-fluid model was then evaluated using a computational fluid dynamic (CFD) solver and the predictions were compared with experimental data. Good agreement was observed for a variety of flow conditions.  相似文献   
38.
Researchers used column and flume experiments with uniform silica sand with and without suspended solids to examine the extent and longevity of hydraulic conductivity reduction (HCR) resulting from three anionic polyacrylamide (PAM) application methods, liquid injection, slurry surface, and granular surface application. Low turbidity (0.4 NTU) liquid injection column tests showed 20–65% HCR, likely caused by an extensional viscosity mechanism. HCR increased as turbidity increased, especially at low PAM concentrations. High turbidity (100 NTU) liquid injection column tests showed 66–77% HCR, likely through surficial PAM–clay aggregate filtration. Column and adsorption tests strongly suggest PAM–sand adsorption does not cause substantial HCR. In low turbidity flume tests, PAM slurry application to the sand surface produced up to 100% HCR, likely through a viscosity mechanism, and granular application to the media surface produced up to 100% HCR, likely through fixed surficial polymer gel formation. Hydraulic conductivity returned to control-adjusted pretreatment levels following PAM application in all tests except granular surface application at high mass loads or with high turbidity.  相似文献   
39.
Increased striatal dopamine D2 receptor activity is thought to contribute to the pathophysiology of schizophrenia. To model this condition in mice, Kellendonk et al. (2006) generated transgenic mice that selectively overexpress the D2 receptor in striatum (D2OE). Drew et al. (2007) reported that D2OE mice display deficits in interval timing and motivation. The present study further explored the impaired timing in D2OE mice. Experiment 1 assessed the role of motivation in producing timing deficits in the peak procedure and found that performance in D2OE mice was improved by increasing motivation. In addition, performance was impaired in control mice when motivation was decreased. In Experiment 2, we found that D2OE mice have no timing impairment when tested using the bisection task, a procedure in which the measure of timing performance is less influenced by motivation to respond. In Experiment 3, we also used the bisection task and found selective impairment in timing of long durations in D2OE mice. These results suggest that striatal D2 overexpression impairs timing by decreasing motivation and through its impact on working memory and/or sustained attention. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
40.
This paper presents United States energy portfolios for the year 2030, developed from seven different Perspectives. The Perspectives are characterized by different weights placed on fourteen defining values (e.g., cost, social acceptance). The portfolios were constructed to achieve three primary goals, energy independence, energy security, and greenhouse gas reductions. The portfolios are also evaluated over a comprehensive set of secondary criteria (e.g., economic growth, technical feasibility). It is found that very different portfolios based on very different defining values can achieve the three primary goals. Commonalities among the portfolios include reliance upon cellulosic ethanol, nuclear power, and energy efficiency to meet year 2030 energy demands. It is concluded that the US energy portfolio must be diverse and to achieve national energy goals will require an explicit statement of goals, a strong role for government, and coordinated action across society.  相似文献   
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