全文获取类型
收费全文 | 623篇 |
免费 | 10篇 |
专业分类
电工技术 | 10篇 |
综合类 | 1篇 |
化学工业 | 105篇 |
金属工艺 | 7篇 |
机械仪表 | 15篇 |
建筑科学 | 7篇 |
能源动力 | 13篇 |
轻工业 | 69篇 |
水利工程 | 3篇 |
石油天然气 | 2篇 |
无线电 | 31篇 |
一般工业技术 | 65篇 |
冶金工业 | 209篇 |
原子能技术 | 3篇 |
自动化技术 | 93篇 |
出版年
2023年 | 3篇 |
2022年 | 7篇 |
2020年 | 3篇 |
2019年 | 6篇 |
2018年 | 7篇 |
2017年 | 7篇 |
2016年 | 7篇 |
2015年 | 10篇 |
2014年 | 9篇 |
2013年 | 16篇 |
2012年 | 17篇 |
2011年 | 31篇 |
2010年 | 27篇 |
2009年 | 14篇 |
2008年 | 24篇 |
2007年 | 19篇 |
2006年 | 20篇 |
2005年 | 20篇 |
2004年 | 20篇 |
2003年 | 11篇 |
2002年 | 9篇 |
2001年 | 11篇 |
2000年 | 9篇 |
1999年 | 22篇 |
1998年 | 55篇 |
1997年 | 36篇 |
1996年 | 25篇 |
1995年 | 14篇 |
1994年 | 11篇 |
1993年 | 17篇 |
1992年 | 5篇 |
1991年 | 4篇 |
1990年 | 13篇 |
1989年 | 7篇 |
1988年 | 7篇 |
1987年 | 15篇 |
1986年 | 7篇 |
1985年 | 12篇 |
1984年 | 9篇 |
1981年 | 5篇 |
1980年 | 3篇 |
1979年 | 3篇 |
1976年 | 5篇 |
1975年 | 7篇 |
1974年 | 8篇 |
1973年 | 2篇 |
1972年 | 5篇 |
1970年 | 4篇 |
1969年 | 5篇 |
1946年 | 2篇 |
排序方式: 共有633条查询结果,搜索用时 0 毫秒
1.
Protsko L.B. Sorenson P.G. Tremblay J.P. Schaefer D.A. 《IEEE transactions on pattern analysis and machine intelligence》1991,17(1):10-21
The authors formulate the criteria for drawing dataflow diagrams and describe the placement and routing algorithms used in a system called MONDRIAN. A generalized approach to the question of software diagrams is proposed based on the authors' experience with MONDRIAN and a metasystem approach to the creation of CASE (computer-aided software engineering) environments. A formal approach to the definition of software objects and their graphical representation is given. The use of location constraints as a basis for generalized layout algorithms is discussed 相似文献
2.
3.
Dale W Schaefer 《Polymer》1984,25(3):387-394
A model is developed to analyse the concentration dependence of the range ξ? of the monomer pair correlation function. In semidilute solution, three concentration regimes are found for semiflexible molecules and the crossover points between the various regimes are predicted in terms of the characteristic ratio of the chains in dilute solution and in terms of the Flory interaction parameter χ. A simple physical interpretation is given which explains the concentration dependence of ξ? based on binary contacts initially and then ternary contacts at higher concentration. Temperature-concentration diagrams are developed for several common polymer-solvent systems. 相似文献
4.
The mechanical properties of moist samples of fine, polydisperse powders are investigated by measuring the tensile strength by a diametrical compression test and the stress—strain relationship of samples exposed to uniaxial compression. The strengths determined by the two methods correlate well. The strength of moist samples compressed to porosities comparable to the level of intragranular porosities achieved by granulation in high-speed mixers is shown to be influenced significantly by particle interactions in addition to mobile liquid bondings. For a particular material the strength is controlled mainly by porosity and liquid saturation. It is shown that the effect of a growing liquid saturation is to reduce particle interactions and thus to facilitate densification during granulation. The deformability of moist samples, which is dependent on strength and deformation behaviour, is assessed for lactose and dicalcium phosphate. 相似文献
5.
Dietary vitamin E effect on color stability and sensory assessment of spoilage in three beef muscles
Effects of dietary vitamin E supplementation (1204 IU/head/day) for 122 days on color stability and microbial load on beef m. longissimus lumborum (LL), m. gluteus medius (GM) and m. psoas major (PM) were studied by subjective and objective evaluation. Color stability of these muscles followed the order LL > GM > PM (p < 0.05). Vitamin E-treated LL, GM and PM showed less metmyoglobin formation, higher a* values and lower hue angle values than controls during storage at 4 °C (p < 0.05). Sensory evaluation demonstrated that panelists preferred the appearance of vitamin E-treated LL, GM and PM beef steaks. Vitamin E supplementation did not affect total microbial load on LL, PM and GM and did not influence panelists' olfactory assessment of microbial spoilage of beef. Endogenous -tocopherol concentration and lipid stability of microsomal fractions of LL, GM and PM were greater (p < 0.05) in vitamin E-treated muscles relative to controls. There was no muscle effect on the pro-oxidant activity of microsomes towards oxymyoglobin oxidation (p > 0.05). Oxymyoglobin stability was greater in the presence of microsomal fractions obtained from vitamin E-treated muscle than in those from controls. Dietary vitamin E supplementation delayed oxymyoglobin oxidation in LL, PM and GM muscle and increased the color shelf-life of these muscles without affecting total microbial load. 相似文献
6.
H.Kirchberger S.Pargfrieder P.Kettner C.Schaefer 《电子工业专用设备》2005,34(5):33-40
化合物半导体材料的应用经历了稳定的增长,尤其是在光电子产业中更为典型。这些材料的应用要求在封装之前需将衬底减薄到100μm以下。由于这种材料的易碎性,需要某种支持方式来通过各种工序对衬底进行处理。半导体行业中建造这种支持最公认的方法是临时固定这种衬底材料到刚性载体基底上。介绍了一种用全自动方式固定和解固定这类衬底的技术。通过采用各种中间基底,包括热和紫外光释放的能够预先准备和薄片状的全自动化干式黏性膜。200mm直径的这种衬底可以以片盒到片盒的方式键合到晶圆平面的这种载体上。本工艺中选用了一种保护性涂层到衬底上。一旦这种衬底固定后,便可以完成随后的减薄、通孔印刷等工序。当这种衬底被减薄和背面处理之后,第二道加工便用于从载体上解键合该衬底,再次以片盒到片盒的方式将其固定到划版的薄膜或类似的载体上。 相似文献
7.
Lipson J. Upadhyayula L.C. Huang S.-Y. Roxlo C.B. Flynn E.J. Nitzsche P.M. McGrath C.J. Fenderson G.L. Schaefer M.S. 《Microwave Theory and Techniques》1990,38(5):483-493
The progress towards developing AM lightwave links for the transmission of multiple TV signals is reported. While the signal-quality objectives and transmission distances are appropriate for CATV trunking, the technology is expected to have applicability to the distribution of video signals in the subscriber loop. Highly linear 1.3-μm distributed feedback (DFB) lasers designed expressly for analog requirements are used to transmit 42 continuous wave carriers according to the standard US CATV frequency plan. For the best lasers, when evaluated over 12 km of fiber, carrier to noise was >52 dB, composite second-order distortion was >70 dBc, and composite triple beat was >70 dBc. The relationship between measurements with continuous wave carriers and actual video signals is discussed. System design rules are offered. Properties that lead to superior analog performance are discussed. Data from 700 links indicate that composite third-order distortion generally scales with product count but that composite second-order distortion has a significant frequency-dependent component 相似文献
8.
Eighty beef crossbred steers with an average weight of 493 kg (4·66 kg SD) were allocated at random to one of five treatments to assess the effects of withholding feed and water on carcass shrinkage and meat quality. The five treatments were: slaughter from the feedlot (T1); and 12, 24, 36 and 48 h periods without feed and water prior to slaughter (T2-5).Weights were taken of the live animal and the carcass to monitor shrinkage along with relevant meat quality measurements. There were no treatment differences (P > 0·05) in initial farm weight, but plant weight shrinkage increased from 31gkg(-1) for T1 to 106 g kg(-1) for T5. Warm carcass weight decreased (P < 0·05) from 278·8 kg for T1, to 270·7 kg for T3 and 261·9 kg for T5. Liver, alimentary tract components, hide and head decreased as a proportion of farm weight as time without feed and water increased. Muscle pH at 6 days post mortem was increased (P < 0·05) in T3-5 compared to T1, with the result that muscle colour became darker, and steaks had less drip loss. Shear values increased (P < 0·05) from 6·3 kg in T1 to 7·7 kg in T4 and T5 indicating an increase in muscle toughness as time without feed and water increased. It was concluded that steers lose live weight rapidly within the first 24 h without feed and water, and that these relatively short periods of time (24 h) can have detrimental effects on carcass shrinkage and muscle quality. 相似文献
9.
André Medeiros De Andrade Roberto Ferreira Machado Michel Ulisses Franz Bremer Carlos Ernesto Gonçalves Reynaud Schaefer Jefferson Cardia Simões 《International journal of remote sensing》2018,39(8):2238-2254
The aim of this work is to produce a simplified vegetation map of ice-free areas of the Fildes Peninsula (FP) and Ardley Island (AI) thought object-oriented classification using a QuickBird satellite image and to evaluate the influence of the global solar radiation (GSR) over the vegetation distribution. The vegetation data were generated from multiresolution segmentation using the panchromatic and infrared layers, and for the classification we calculated the normalized vegetative difference index (NVDI) and the green NVDI. Two classes were created – Lichen and Moss Cushion SubFormation and Moss Subformation – with 48 vegetation samples collected on surveys during the austral summers of 2008 and 2009. We used a kappa index to evaluate the classification efficiency using 100 sampled points obtained in austral summer of 2013. The GSR was estimated, and in order to evaluate the effect of meteorological phenomena and cloudless, we measured the GSR using a net radiometer model CNR4 installed in FP between 2014 and 2016. The estimate of GSR was done for seasons of 2015, in order to estimate the light compensation point and the saturation point for the plant communities in FP and AI. The kappa index was 0.73 and the global accuracy was 0.78, showing consistency between the classification and ground truth. The area was covered by vegetation in FP was 16.7% and in AI is 59.1%. The vegetation cover is distributed differently at FP and AI, and our results suggest GSR plays an important role in vegetation distribution and these tendencies could be related to greater GSR demand by mosses when compared to lichens. 相似文献
10.
Thomas M. Odell Chong-Hua Xu Paul W. Schaefer Barbara A. Leonhardt De-Fu Yao Xiang-De Wu 《Journal of chemical ecology》1992,18(12):2153-2159
Pheromone traps baited with (+)-disparlure,cis-7,8-epoxy-2methyocta-decane, captured males ofLymantria dispar, L. monacha, andL. mathura in northeastern People's Republic of China.L. dispar responded to the addition of olefin to (+)-disparlure-baited traps in a negative doseresponse manner. Observations on site and seasonal capture ofL. dispar andL. mathura are discussed.Lepidoptera: Lymantriidae. 相似文献