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101.
102.
Dov Bahat 《Journal of Materials Science》1978,13(12):2548-2554
The displacive transformations in quartz, hexacelsian and the strontium equivalent of the latter, are homogeneous incipient
transformations. These transformations are carried out mostly as a second (or higher) order reaction, and are finally completed
abruptly as a first-order reaction which results from a sudden release of strain accumulated due to bond stretching. In such
transformations the first-order mode of reaction seems to be eliminated to various extents by the introduction of impurities
as solid solution to the structure. Such impurities promote heterogeneous transformations. The extent of sluggishness of displacive
transformations and of stability relationship in alkaline earth feldspars is correlated with the various ionic sizes of barium,
strontium and calcium. Displacive and diffusive transformations in alkali feldspars are also homogeneous incipient transformations,
but due to the high mobility of the alkali ions, building up of strain is prevented and no abrupt change in symmetry occurs
at the transformation. The hexacelsian ⇌ celsian and monotropic transformations in SrAl2Si2O8 and CaAl2Si2O8 are heterogeneous incipient reconstructive transformations. Differences in melting temperatures reported in the past for
BaAl2Si2O8 may probably be correlated with the grain size, crystalline modification and extent of Al/Si order in the sample investigated. 相似文献
103.
Soreni-Harari M Yaacobi-Gross N Steiner D Aharoni A Banin U Millo O Tessler N 《Nano letters》2008,8(2):678-684
We demonstrate tuning of the electronic level positions with respect to the vacuum level in colloidal InAs nanocrystals using surface ligand exchange. Electrochemical as well as scanning tunneling spectroscopy measurements reveal that the tuning is largely dependent on the nanocrystal size and the surface linking group, while the polarity of the ligand molecules has a lesser effect. The implications of affecting the electronic system of nanocrystal through its capping are illustrated through prototype devices. 相似文献
104.
Dov Dori Somwang Thipphayathetthana 《International Journal of Satellite Communications and Networking》2016,34(2):295-319
Three persistent common problems in satellite ground control software are obsolescence, lack of desired features and flexibilities, and endless software bug fixing. The obsolescence problem occurs when computer and ground equipment hardware become obsolete, usually after only one‐third into the satellite mission lifetime. The software needs to be updated to accommodate changes on the hardware side, requiring significant work of satellite operators to test, verify, and validate these software updates. Trying to help solve these problems, we have proposed an object‐process methodology model and guidelines for developing satellite ground control software. The system makes use of a database‐driven application and concepts of object‐process orientation and modularity. In the new proposed framework, instead of coding each software function separately, the common base functions will be coded, and combining them in various ways will provide the different required functions. The formation and combination of these base functions will be governed by the main code, definitions, and database parameters. These design principles will make sure that the new software framework would provide satellite operators with the flexibility to create new features and enable software developer to find bugs quicker and fix them more effectively. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
105.
An analytical model is presented that describes the bending process following the absorption of a Gaussian laser pulse by the surface of a moderately thick metal plate. The model is based on the constitutive equations of thermoelastoplasticity and therefore fundamentally describes this optodynamic process. Assuming relatively short laser pulses, Green's function is used as an approximation for the real plate temperature. The plate is assumed to be made of elastic, linearly hardening material. 相似文献
106.
Current reinforced earth structure designs arbitrarily distinguish between reinforced walls and slopes, that is, the batter of walls is 20° or less while in slopes it is larger than 20°. This has led to disjointed design methodologies where walls employ a lateral earth pressure approach and slopes utilize limit equilibrium analyses. The earth pressure approach used is either simplified (e.g., ignoring facing effects), approximated (e.g., considering facing effects only partially), or purely empirical. It results in selection of a geosynthetic with a long-term strength that is potentially overly conservative or, by virtue of ignoring statics, potentially unconservative. The limit equilibrium approach used in slopes deals explicitly with global equilibrium only; it is ambiguous about the load in individual layers. Presented is a simple limit equilibrium methodology to determine the unfactored global geosynthetic strength required to ensure sufficient internal stability in reinforced earth structures. This approach allows for seamless integration of the design methodologies for reinforced earth walls and slopes. The methodology that is developed accounts for the sliding resistance of the facing. The results are displayed in the form of dimensionless stability charts. Given the slope angle, the design frictional strength of the soil, and the toe resistance, the required global unfactored strength of the reinforcement can be determined using these charts. The global strength is then distributed among individual layers using three different assumed distribution functions. It is observed that, generally, the assumed distribution functions have secondary effects on the trace of the critical slip surface. The impact of the distribution function on the required global strength of reinforcement is minor and exists only when there is no toe resistance, when the slope tends to be vertical, or when the soil has low strength. Conversely, the impact of the distribution function on the maximum unfactored load in individual layers, a value which is typically used to select the geosynthetics, can result in doubling its required long-term strength. 相似文献
107.
Vectorisation of raster line images is a relatively mature subject in the document analysis and recognition field, but it
is far from being perfect as yet. We survey the methods and algorithms developed to-date for the vectorisation of document
images, and classify them into six categories: Hough transform-based, thinning-based, contour-based, run-graph-based, mesh-pattern-based,
and sparse-pixel-based. The purpose of the survey is to provide researchers with a comprehensive overview of this technique,
to enable a judicious decision while selecting a vectorisation algorithm for a system under development or a newly developed
vectorisation algorithm.
Received: 10 November 1998?Received in revised form: 7 January 1999?Accepted: 7 January 1999 相似文献
108.
Yueng-Hsiang Huang Dov Zohar Michelle M. Robertson Angela Garabet Lauren A. Murphy Jin Lee 《Accident; analysis and prevention》2013
Purpose
The objective of this study was to develop and test the reliability and validity of a new scale designed for measuring safety climate among mobile remote workers, using utility/electrical workers as exemplar. The new scale employs perceived safety priority as the metric of safety climate and a multi-level framework, separating the measurement of organization- and group-level safety climate items into two sub-scales. The question of the emergence of shared perceptions among remote workers was also examined.Method
For the initial survey development, several items were adopted from a generic safety climate scale and new industry-specific items were generated based on an extensive literature review, expert judgment, 15-day field observations, and 38 in-depth individual interviews with subject matter experts (i.e., utility industry electrical workers, trainers and supervisors of electrical workers). The items were revised after 45 cognitive interviews and a pre-test with 139 additional utility/electrical workers. The revised scale was subsequently implemented with a total of 2421 workers at two large US electric utility companies (1560 participants for the pilot company and 861 for the second company). Both exploratory (EFA) and confirmatory factor analyses (CFA) were adopted to finalize the items and to ensure construct validity. Reliability of the scale was tested based on Cronbach's α. Homogeneity tests examined whether utility/electrical workers’ safety climate perceptions were shared within the same supervisor group. This was followed by an analysis of the criterion-related validity, which linked the safety climate scores to self-reports of safety behavior and injury outcomes (i.e., recordable incidents, missing days due to work-related injuries, vehicle accidents, and near misses).Results
Six dimensions (Safety pro-activity, General training, Trucks and equipment, Field orientation, Financial Investment, and Schedule flexibility) with 29 items were extracted from the EFA to measure the organization-level safety climate. Three dimensions (Supervisory care, Participation encouragement, and Safety straight talk) with 19 items were extracted to measure the group-level safety climate. Acceptable ranges of internal consistency statistics for the sub-scales were observed. Whether or not to aggregate these multi-dimensions of safety climate into a single higher-order construct (overall safety climate) was discussed. CFAs confirmed the construct validity of the developed safety climate scale for utility/electrical workers. Homogeneity tests showed that utility/electrical workers’ safety climate perceptions were shared within the same supervisor group. Both the organization- and group-level safety climate scores showed a statistically significant relationship with workers’ self-reported safety behaviors and injury outcomes.Implications
A valid and reliable instrument to measure the essential elements of safety climate for utility/electrical workers in the remote working situation has been introduced. The scale can provide an in-depth understanding of safety climate based on its key dimensions and show where improvements can be made at both group and organization levels. As such, it may also offer a valuable starting point for future safety interventions. 相似文献109.
目的:研究扩展青霉侵染对苹果果实膜透性及膜磷脂代谢的影响.方法:以'元帅'苹果为试材,测定扩展青霉损伤接种果实病健交界处组织的细胞膜透率、膜磷脂代谢关键酶活力以及相关底物和产物含量的变化.结果:扩展青霉侵染早期(2 d前)果实病斑直径无明显变化,侵染后期(2 d后)果实病斑直径和细胞膜透率明显增大.侵染期间,果实的磷脂... 相似文献
110.
Negotiating Norms of Discussion in the Public Arena: The Use of Irony in Israeli Political Radio Phone‐In Programs
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Phone‐in radio programs are part of the public sphere and thus require open access, rationality, and practicality. Simultaneously, they are a media product, which requires entertaining content. We demonstrate these demands through the analysis of interactional irony in Israeli political radio phone‐ins. From an emic perspective, callers see irony as detrimental to the discussions, yet hosts and regular callers use it to make entertaining interactions. Irony is a critical tool that points to violations of norms: the norm of a clear 2‐sided interaction; norms akin to the Habermasian public sphere; and at the content level, irony is used to reject racist positions. Being indirect, irony can be used to create an entertaining yet critical discussion in the public sphere. 相似文献