全文获取类型
收费全文 | 462篇 |
免费 | 4篇 |
专业分类
电工技术 | 6篇 |
综合类 | 2篇 |
化学工业 | 63篇 |
金属工艺 | 6篇 |
机械仪表 | 17篇 |
建筑科学 | 34篇 |
矿业工程 | 1篇 |
能源动力 | 1篇 |
轻工业 | 208篇 |
无线电 | 6篇 |
一般工业技术 | 33篇 |
冶金工业 | 17篇 |
自动化技术 | 72篇 |
出版年
2016年 | 2篇 |
2014年 | 3篇 |
2013年 | 100篇 |
2011年 | 9篇 |
2010年 | 4篇 |
2009年 | 5篇 |
2008年 | 7篇 |
2007年 | 10篇 |
2006年 | 14篇 |
2005年 | 8篇 |
2004年 | 11篇 |
2003年 | 11篇 |
2002年 | 10篇 |
2001年 | 6篇 |
2000年 | 6篇 |
1999年 | 3篇 |
1998年 | 11篇 |
1997年 | 17篇 |
1996年 | 10篇 |
1995年 | 13篇 |
1994年 | 15篇 |
1993年 | 8篇 |
1992年 | 3篇 |
1991年 | 7篇 |
1990年 | 7篇 |
1989年 | 6篇 |
1988年 | 9篇 |
1987年 | 7篇 |
1986年 | 13篇 |
1985年 | 6篇 |
1984年 | 8篇 |
1983年 | 8篇 |
1982年 | 2篇 |
1981年 | 7篇 |
1980年 | 4篇 |
1979年 | 2篇 |
1978年 | 5篇 |
1977年 | 8篇 |
1976年 | 5篇 |
1975年 | 5篇 |
1974年 | 8篇 |
1973年 | 5篇 |
1972年 | 3篇 |
1971年 | 6篇 |
1968年 | 9篇 |
1967年 | 11篇 |
1964年 | 3篇 |
1962年 | 3篇 |
1960年 | 3篇 |
1955年 | 4篇 |
排序方式: 共有466条查询结果,搜索用时 15 毫秒
21.
Abstract This paper presents a method for improving heuristics using a triangulation technique. Instead of using a heuristic to directly estimate distance (X1, X2) between nodes X1 and X2, the proposed technique selects a reference node Ri applies the heuristic to (X1,Ri) and (X2,Ri), and uses the Euclidean distance formula to calculate a new heuristic value. If two nodes are close to each other, then they should also be approximately equidistant to a third reference node. Utilizing a set of many such reference nodes, node expansions can be reduced for a large class of heuristics. Very early results for this method, referred to as multi-dimensional heuristics, showed that fewer node expansions were needed when using the triangulation technique. New results in this paper include the development of a new learning procedure for selecting reference nodes, experimentation on reusing reference node sets for multiple goal instances, a comparison of multi-dimensional heuristics with weighting and how they dynamically weight states near the goal, and some observations which help explain how and why this technique improves heuristics. 相似文献
22.
PETER SCHLUESSEL 《International journal of remote sensing》2013,34(4-5):705-721
Abstract The infrared sensor systems AVHRR (Advanced Very High Resolution Radiometer) and HIRS (High resolution Infrared Radiation Sounder) on board the NOAA-7 satellite are studied theoretically by means of radiative transfer calculations to enable the development of new retrieval techniques for atmospheric water vapour profiles. Simulations of radiometer signals have been performed for a large set of atmospheres from the middle and tropical latitudes. Subsequent development of a physical-statistical retrieval method demonstrates the usefulness of a coupling of both radiometers for water vapour retrievals in a single HIRS field of view. Total column amounts as well as the amounts in thick layers (150-200 hPa (thick) in the lower troposphere can be derived with an accuracy of 5-15 per cent and 15-25 per cent respectively. The amounts in thinner layers (50hPa) can be estimated with accuracies between 20 and 30 per cent. The AVHRR split window channels are a powerful tool in the water vapour retrievals. The technique developed benefits from the simultaneous retrieval of temperature profiles and surface temperatures. Accounting for scan-angle dependencies explicitly leads to improved retrievals. The synergy of AVHRR with HIRS increases the number of retrievals in partially cloudy fields of view compared with HIRS retrievals alone. A case study demonstrates the capability of the method to resolve water vapour structures with a high spatial resolution and its value in areas where conventional measurements from radiosonde ascents are sparse. 相似文献
23.
PETER WINKLER 《Cryptologia》2013,37(4):327-332
The surprising discovery that information can be passed both covertly and legally between bridge partners has added a new dimension to the theory of this popular game. In this paper some of the methods are sketched and their cryptologic foundation is described. 相似文献
24.
The effect of Saccharomyces bayanus-mediated fermentation on the chemical composition and aroma profile of Chardonnay wine 总被引:1,自引:0,他引:1
25.
Abstract Twenty one tenderometers were compared in processing plants for their accuracy of measurement using wax wafers as the test material. The results indicate that there are serious differences among the tenderometers and that the accuracy of measurement is unsatisfactory for the purpose of grading peas to establish the price paid to the grower. If a relationship of compatible trust is to remain between the processor and the grower, serious consideration must be given either to better calibration of currently used tenderometers or to devising some other method of grading and paying for peas. 相似文献
26.
Assimilate translocation in mature grapevines (cv. Gewürztraminer and cv. Harslevelü) under field conditions was investigated during the growth season by quantifying individual sugars and organic acids in mature leaves, shoot bark and berries, as affected by girdling the shoot just above the bunches. Tissue was sampled at berry set, pea size, veraison and ripeness stages of the vine. Invertase activity was determined in the shoot bark at ripeness. In the leaves, malic acid concentrations reached lowest levels at pea size, but increased thereafter. Tartaric acid decreased after peaking at pea size stage. Tartaric acid concentrations increased with girdling. Despite the increase in leaf age, sucrose concentrations remained virtually stable during the season, emphasising the importance of mature leaves for nourishing bunches. Girdling resulted in a build‐up of sucrose in the leaves. In the bark, malic and tartaric acid stayed more or less the same during the growth period, but increased above the girdle. As a result of phloem disruption, sucrose also increased. The increase in glucose and tartaric acid is believed to result from catabolic cleavage of sucrose by invertase. Invertase activity was evident in the bark (of mature Harslevelü vines) at ripeness, which may indicate involvement in osmotic adjustments and gradients in the bark/phloem structure. In the berries, malic and tartaric acids reached peak concentrations at pea size. The volume increase during the ripening period, and in the case of malic acid also respiratory loss, resulted in a decrease in organic acid concentration. Malic acid continued to decrease after the initial decline, whereas tartaric acid stayed virtually stable. Girdling had no marked effect on organic acid accumulation in the berries. Sucrose concentrations were low during the first part of the season, but increased thereafter. Sucrose concentrations during ripening increased with girdling, which may represent a concentration effect and/or import from the rest of the vine. Sucrose concentrations (in mature Harslevelü vines) were indeed lower below than above the girdle. Comparison of sucrose concentrations in the leaves, bark and berries showed the existence of a decreasing concentration gradient, in line with the source:sink transport concept. An equally prominent decrease in sucrose:glucose ratio in the berries from the start of the ripening period indicates that vacuolar integrity (compartmentation) was affected in the ripening berry, most probably allowing hydrolysis of sucrose by invertase and decreasing osmotic potential within the berry. The results provide further evidence for the hypothesis of an osmotic gradient driven transport to the berry. 相似文献
27.
Culture filtrates and mycelial homogenates from over 100 microorganisms were tested for their ability to inhibit catecholase and laccase (o- and p-diphenol oxidase) activity using simple, rapid, colorimetric assays in microtiter plates or polarographic assays using an O2 -electrode. Of the organisms screened, 56 produced inhibition of catecholase activity and 34 gave rise to laccase inhibition, with most of the latter group showing inhibition of both enzymes. The role of this enzyme inhibitor system in plant pathogenicity is also discussed. 相似文献
28.
29.
EFFECT OF PH ON THERMAL PROCESS REQUIREMENTS OF CANNED FOODS 总被引:3,自引:0,他引:3
30.
PETER W. VOISEY 《Journal of texture studies》1975,6(2):253-257
Abstract . Since mastication involves high deformation rates (150cm min?1), the arbitrarily selected slow deformation rates usually used in instrumental texture tests can lead to erroneous results and lack of correlation with sensory evaluation with respect to the order of sample ranking. Sophisticated instrumentation that is costly to operate is required to accurately simulate the deformation rates operating in the mouth. It is suggested that instrumental data obtained at slow rates could be evaluated in a more meaningful manner if series of similar samples were tested at increasing deformation rates and the plotted force/deformation curves extrapolated to 150cm min?1. It is implied that recording systems would be more useful, if in addition to force, they sensed the rate of force change with deformation rate. 相似文献