首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   495篇
  免费   4篇
电工技术   5篇
综合类   1篇
化学工业   69篇
金属工艺   6篇
机械仪表   20篇
建筑科学   33篇
矿业工程   1篇
能源动力   2篇
轻工业   218篇
无线电   8篇
一般工业技术   33篇
冶金工业   15篇
自动化技术   88篇
  2016年   3篇
  2014年   3篇
  2013年   115篇
  2011年   9篇
  2010年   4篇
  2009年   4篇
  2008年   7篇
  2007年   9篇
  2006年   14篇
  2005年   8篇
  2004年   11篇
  2003年   11篇
  2002年   10篇
  2001年   9篇
  2000年   6篇
  1998年   11篇
  1997年   20篇
  1996年   12篇
  1995年   14篇
  1994年   16篇
  1993年   8篇
  1992年   3篇
  1991年   7篇
  1990年   8篇
  1989年   6篇
  1988年   9篇
  1987年   7篇
  1986年   11篇
  1985年   8篇
  1984年   7篇
  1983年   8篇
  1982年   4篇
  1981年   9篇
  1980年   4篇
  1979年   3篇
  1978年   5篇
  1977年   8篇
  1976年   4篇
  1975年   6篇
  1974年   8篇
  1973年   6篇
  1972年   3篇
  1971年   5篇
  1968年   10篇
  1967年   10篇
  1966年   3篇
  1965年   2篇
  1964年   5篇
  1962年   3篇
  1960年   2篇
排序方式: 共有499条查询结果,搜索用时 0 毫秒
61.
62.
Abstract. Different methods used to measure pea tenderness are reviewed. Objective estimation of crop maturity, pea tenderness and quality has concerned researchers for many years. Chemical and mechanical methods have been used, and several instruments developed. There is a high degree of correlation between methods which also appear to agree with sensory analysis. For grading peas to establish the price paid to the grower, accuracy and economy under commercial conditions is of prime importance. Some methods are unsuitable on this basis, and presently used instruments and the manner in which they are operated require improvement.  相似文献   
63.
INVESTIGATED THE CRITERIA EMPLOYED BY ENGINEERS IN THE SELECTION OF VARIOUS TECHNICAL INFORMATION CHANNELS IN PROBLEM-SOLVING ENDEAVORS. FOCUSES ON THE RELATIONSHIPS OF CERTAIN CRITERIA IDENTIFIED IN PAST RESEARCH TO SUCH FACTORS AS FREQUENCY OF CHANNEL UTILIZATION AND THE RATE AT WHICH ENGINEERS ACCEPT OR REJECT TECHNICAL INFORMATION RECEIVED FROM SPECIFIC CHANNELS. A DIRECT RELATIONSHIP IS FOUND BETWEEN PERCEIVED ACCESSIBILITY OF INFORMATION CHANNELS AND SEVERAL OBJECTIVE MEASURES OF UTILIZATION, WHEREAS NO DEFINITE SUPPORT IS FOUND FOR THE HYPOTHESIS THAT THE CHANNELS PERCEIVED HIGHEST IN TECHNICAL QUALITY ARE THOSE USED MOST FREQUENTLY. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
64.
MEASURED VISUAL IMAGERY UNDER SENSORY RESTRICTION AND UNDER RHYTHMIC PHOTIC STIMULATION TO TEST THE HYPOTHESIS THAT HIGH VISUAL-IMAGERY INDIVIDUALS WOULD BE MORE SUSCEPTIBLE TO HYPNOSIS. SUPPORT FOR THE HYPOTHESIS WAS OBTAINED PRIMARILY FROM IMAGERY MEASURES THAT INSTRUCTED 784 STUDENTS TO TRY TO SEE CERTAIN SPECIFIED IMAGES. LITTLE SUPPORT WAS OBTAINED USING LESS PRESCRIPTIVE MEASURES TAPPING FREE, SPONTANEOUS IMAGERY. THE DIMENSIONS OF IMAGERY AND POSSIBLE SEX DIFFERENCES IN VISUAL IMAGERY WERE STUDIED. (29 REF.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
65.
The functionality of butterfat can be improved by fractionation, a process that can be considered as enrichment of butterfat with long-chain saturated fatty acids. Model hard fractions were produced by adding tripalmitin to butterfat, in ratios from 0.9:0.1 through 0.1:0.9. The model system had very similar thermal behavior and mechanical properties to true fractions. The phase behavior of tripalmitin/butterfat mixtures was determined. Such butterfat fractions have potential as a moisture barrier in edible films and coatings. Tripalmitin-enriched butterfat is an alternative to hard butterfat fractions in some applications.  相似文献   
66.
The rheology of 10 Australian honeys was investigated at temperatures ?15C to 0C by a strain‐controlled rheometer. The honeys exhibited Newtonian behavior irrespective of the temperature, and follow the Cox–Merz rule. G″/G′ and ω are quadratically related, and the crossover frequencies for liquid to solid transformation and relaxation times were obtained. The composition of the honeys correlates well (r2 > 0.83) with the viscosity, and with 247 data sets (Australian and Greek honeys), the following equation was obtained: The viscosity of the honeys showed a strong dependence on temperature, and four models were examined to describe this. The models gave good fits (r 2 > 0.95), but better fits were obtained for the WLF model using Tg of the honeys and µg= 1011 Pa.s. The WLF model with its “universal values” poorly predicted the viscosity, and the implications of the measured rheological behaviors of the honeys in their processing and handling are discussed.  相似文献   
67.
Lysozyme is an enzyme with muramidase activity which can lyse Gram-positive bacteria, including wine lactic acid bacteria. This enzyme provides a practical method for delaying or preventing the growth of Oenococcus oeni and consequently the onset of malolactic fermentation during the vinification of red and white wines. This paper reports the impact of lysozyme on the chemical and sensorial properties of commercially vinified red (Cabernet Sauvignon and Shiraz) and white (Riesling) wines. The addition of lysozyme to these wines had little or no effect on the content of alcohol, free and total sulfur dioxide and titratable acidity, and pH value. The lysozyme retained 75–80% activity in the Riesling wine after six months, however no detectable activity remained in the Cabernet Sauvignon and Shiraz wines after two days. Upon addition of lysozyme to both of the red wines, a rapid initial decrease (up to 17%) in red wine colour density and phenolic content occurred in association with the formation of a light precipitate. The reduction in red wine colour was also noted by the sensory panel. When added to the Riesling wine, lysozyme did not cause an increase in browning over the six month storage time, but did induce heat instability (haze), suggesting that white wines may require protein stabilisation following treatment with lysozyme. Sensory assessment by triangle difference testing revealed that, during the six month storage period, treatment with lysozyme did not cause important changes to either the aroma or palate of the red and white wines tested.  相似文献   
68.
Given their perennial nature, grapevines can respond to deficit irrigation during both the current season as well as during the following season, even though full irrigation may have been restored during that second season. To define the cropping responses involved, three post-veraison irrigation treatments were imposed on spur, mechanically and minimally pruned Shiraz vines that were already receiving restricted water application using Partial Rootzone Drying (PRD). The treatments resulted in the vines receiving 1.25 ML per hectare pre veraison and the three irrigation treatments receiving 1.25, 0.65 and 0 ML of water per hectare in the post-veraison period. Water deficit during the current season reduced berry and bunch weight, and yield. Sugar concentration was reduced, and phenolic concentration increased when less water was applied, but anthocyanin concentration was unaffected. Although irrigation was returned to standard practice (PRD) in the following season, yield was reduced in accordance with deficit irrigation treatments the previous season. This reduction in yield was primarily caused by fewer bunches per vine, which in turn was a direct consequence of fewer shoots per vine (lower budburst). The lower crop load on the vines that had received restricted irrigation post-veraison in the previous season resulted in higher sugar and antho-cyanin concentrations in fruit the following season. Lighter pruning resulted in a greater number of smaller bunches comprising smaller berries. In both seasons the minimal pruning treatment delayed fruit maturity as measured by sugar accumulation. Post-veraison water deficit thus has the potential to impact on both yield and fruit composition during the current season as well as during the subsequent season.  相似文献   
69.
70.
A single number called the "strength" does not serve to describe adequately the fracture properties of glass subjected to a slowly increasing tensile stress. Instead, it is found that the surface where fracture originates may be represented as a continuum over which flaws of differing "critical breaking stresses" are distributed. The distribution function for the flaws is given by S σ where σ is the tensile stress initiating fracture and S and b are constants which are properties of the surface for slowly increasing stresses. The testing procedure and nature of the flaws are discussed.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号