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Twenty-one 15- to 17-year-olds attempted to purchase cigarettes in 232 stores in the manner that confederates typically do in access studies, as well as in the manipulative ways (e.g., lying about their ages) that youth smokers do, thereby modeling youth access to tobacco within versus outside of studies, respectively. Youth typical-research versus manipulative behavior was contrasted with clerk behavior (requests for youth ID cards) to examine the relative contributions of both to youth access to tobacco for the 1st time. Results revealed that clerk behavior was the strongest predictor of cigarette sales to youth and hence underscore the need for interventions with merchants. Sales nonetheless were higher under youth-manipulative conditions and thereby highlight the low ecological validity of access research. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
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Gel permeation chromatography (GPC) was used to investigate the course of the sodium hydroxide catalysed methylolation of phenol in dilute aqueous solution. At low concentrations, the initial rate of methylolation was directly proportional to the concentrations of sodium hydroxide and of formaldehyde. By computer integration of the rate equations for the methylolation of phenol, of 2-methylol phenol and of 4-methylol phenol, the experimental rate curves were simulated and optimal values for the rate constants of all the methylolation steps were obtained. 相似文献
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Douglas A Stow Allen Hope David Verbyla Fred Huemmrich Charles Racine Kenneth Tape Kenji Yoshikawa Brian Noyle David Douglas Gensuo Jia Donald Walker Aaron Petersen Ranga Myneni 《Remote sensing of environment》2004,89(3):281-308
The objective of this paper is to review research conducted over the past decade on the application of multi-temporal remote sensing for monitoring changes of Arctic tundra lands. Emphasis is placed on results from the National Science Foundation Land-Air-Ice Interactions (LAII) program and on optical remote sensing techniques. Case studies demonstrate that ground-level sensors on stationary or moving track platforms and wide-swath imaging sensors on polar orbiting satellites are particularly useful for capturing optical remote sensing data at sufficient frequency to study tundra vegetation dynamics and changes for the cloud prone Arctic. Less frequent imaging with high spatial resolution instruments on aircraft and lower orbiting satellites enable more detailed analyses of land cover change and calibration/validation of coarser resolution observations.The strongest signals of ecosystem change detected thus far appear to correspond to expansion of tundra shrubs and changes in the amount and extent of thaw lakes and ponds. Changes in shrub cover and extent have been documented by modern repeat imaging that matches archived historical aerial photography. NOAA Advanced Very High Resolution Radiometer (AVHRR) time series provide a 20-year record for determining changes in greenness that relates to photosynthetic activity, net primary production, and growing season length. The strong contrast between land materials and surface waters enables changes in lake and pond extent to be readily measured and monitored. 相似文献
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A. S. Hope Corresponding author K. R. Pence D. A. Stow 《International journal of remote sensing》2013,34(20):4237-4250
The relationship between normalized difference vegetation index (NDVI) patterns obtained from high spatial resolution aircraft and low spatial resolution satellite data (Advanced Very High Resolution Radiometer (AVHRR)) was investigated with the intent of using multilevel data to scale carbon flux models in Arctic tundra ecosystems. Despite variable illumination conditions during the aircraft missions and maximum value compositing of the AVHRR data, the difference between 3?km average aircraft and AVHRR NDVI values was generally constant along each flight transect. However, the magnitude of the offset differed between flight dates and small lakes had a greater effect on area averaged aircraft NDVI values than on the satellite values. A cloud index was calculated using incident solar radiation measured by the aircraft and this index was used to identify periods when the aircraft NDVI values may have been biased by cloud cover. Removal of NDVI values based on a cloud index threshold did not appear to be justified given the marginal improvement in the relationship between the two NDVI datasets. If the systematic difference between AVHRR and aircraft NDVI values can be determined, then the scaling of carbon flux models based on the NDVI should be a viable approach in Arctic ecosystems. 相似文献
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Hope Hui Rising 《Journal of Urban Design》2019,24(3):424-442
Kevin Lynch’s theory of imageability was used to examine the contributions of imageability elements (landmarks, paths, nodes, edges and districts) and components (structure, identity and meaning) to the image of the water city. Through conducting cognitive mapping, photovoice and non-visual protocols in eight cities, waterscape mappability, identifiability and attachment were measured as water-based structure, identity and meaning. To generate measures for the image of the water city, independent raters evaluated the identifiability of sketch maps. Regression analyses suggest that only canal mappability (the structure of water-based paths) significantly contributed to all measures for the image of the water city. 相似文献
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The healthcare system needs to track and monitor patients’ status and information. One of the most important requirements is that the patient is able to access the service anywhere at any time. Systems are being developed using the Internet to monitor patients’ status, and in some areas, especially rural areas and motorways, the Internet may not be available, even though the mobile network is available. In some cases, the network might be overloaded, so the patient information cannot be delivered to the hospital or medical centre. We propose a new method that uses the spare extension of the random access channel (RACH), which is carried by physical random access channel (PRACH) to send the patient information to the medical centre. We present the mathematical model of the channel and compare the results with another system from 3GPP to evaluate the results. The results show that the proposed method needs less time to transmit the patient’s information. 相似文献
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