全文获取类型
收费全文 | 116篇 |
免费 | 1篇 |
国内免费 | 10篇 |
专业分类
电工技术 | 3篇 |
综合类 | 12篇 |
化学工业 | 27篇 |
金属工艺 | 25篇 |
机械仪表 | 8篇 |
轻工业 | 1篇 |
一般工业技术 | 1篇 |
冶金工业 | 38篇 |
自动化技术 | 12篇 |
出版年
2021年 | 2篇 |
2020年 | 1篇 |
2019年 | 1篇 |
2018年 | 3篇 |
2017年 | 3篇 |
2015年 | 2篇 |
2014年 | 4篇 |
2013年 | 6篇 |
2012年 | 11篇 |
2011年 | 11篇 |
2010年 | 3篇 |
2009年 | 8篇 |
2008年 | 6篇 |
2007年 | 5篇 |
2006年 | 5篇 |
2005年 | 8篇 |
2004年 | 5篇 |
2002年 | 3篇 |
2001年 | 3篇 |
2000年 | 3篇 |
1999年 | 3篇 |
1998年 | 3篇 |
1996年 | 3篇 |
1995年 | 3篇 |
1994年 | 2篇 |
1993年 | 2篇 |
1992年 | 2篇 |
1991年 | 1篇 |
1990年 | 3篇 |
1989年 | 2篇 |
1988年 | 2篇 |
1987年 | 1篇 |
1986年 | 2篇 |
1984年 | 1篇 |
1982年 | 1篇 |
1981年 | 2篇 |
1977年 | 1篇 |
排序方式: 共有127条查询结果,搜索用时 15 毫秒
1.
介绍了带钢热连轧过程中电动活套和液压活套各自的张力控制模型,前者以电机电流作为控制对象,后者以液压缸压力作为控制对象。 相似文献
2.
Li Jianxiong R. Gries G. Gries K. N. Slessor G. G. S. King W. W. Bowers R. J. West 《Journal of chemical ecology》1993,19(6):1057-1062
Of the four possible stereoisomers of 5,11-dimethylheptadecane, the major sex pheromone component of the eastern hemlock looper (EHL),Lambdina fiscellaria fiscellaria Guen., and the western hemlock looper (WHL),Lambdina fiscellaria lugubrosa Hulst, (5R,11S)-5,11-dimethylheptadecane was the only stereoisomer eliciting electrophysiological responses by male EHL and WHL antennae. In field bioassays with EHL and WHL populations, traps baited with (5R,11S)-5, 11-dimethylheptadecane caught as many males as did traps baited with all four stereoisomers combined or a synthetic mixture of 5,11-dimethylheptadecanes. Catches in traps baited with the other three stereoisomers did not significantly differ from those in the unbaited control traps. We conclude that male antennae lack chemoreceptors for the other three stereoisomers of 5,11-dimethylheptadecane and hypothesize that only (5R,115)-5,11-dimethylheptadecane is produced by female EHLs and WHLs. 相似文献
3.
Soybean plant volatiles, extracted as steam distillates, significantly affected the behavior and biology of the cabbage looper,Trichoplusia ni (Hübner) (Lepidoptera: Noctuidae). Distillates from the susceptible Davis variety attractedT. ni larvae and female adults, whereas those from resistant PI 227687 plants repelled them. When mixed in an artificial diet, steam distillates from PI 227687 plants caused mortality of first-instar larvae. Adults emerging from pupae topically treated with 5 g of such PI 227687 extractable showed developmental abnormalities. Larval feeding was significantly less on Davis leaves treated with PI 227687 volatiles as compared to solvent (acetone) or such Davis extractables. However, Davis volatiles on PI 227687 leaves did not increase larval feeding. HPLC analyses of steam distillates from susceptible Davis versus resistant PI 227687 indicated differences. 相似文献
4.
A Flavanone and Two Phenolic Acids from Chrysanthemum morifolium with Phytotoxic and Insect Growth Regulating Activity 总被引:2,自引:0,他引:2
Beninger CW Abou-Zaid MM Kistner AL Hallett RH Iqbal MJ Grodzinski B Hall JC 《Journal of chemical ecology》2004,30(3):589-606
Leaves of Chrysanthemum morifolium cv. Ramat were extracted sequentially with hexane, ethyl acetate, and methanol. The methanol fraction, when incorporated into artificial diet was found to reduce the growth of cabbage looper (Trichoplusia ni Hubner) larvae at concentrations between 500 and 5000 ppm of diet. Fractionation of the methanol extract on a Sephadex column yielded five fractions, three of which reduced the weight of larvae relative to the control. One fraction was analyzed using high performance liquid chromatography (HPLC) and found to contain three main constituents. These compounds were purified using a combination of gel permeation chromatography on Sephadex LH20 and HPLC, and analyzed by 1H and 13CNMR as well as undergoing chemical and physical analyses. The compounds were identified as: 1, chlorogenic acid (5-O-caffeoylquinic acid); 2, 3,5-O-dicaffeoylquinic acid; and 3, 3', 4',5-trihydroxyflavanone7-O-glucuronide (eriodictyol7-O-glucuronide). At concentrations between 100 to 1000 ppm these compounds reduced both growth and photosynthesis of Lemna gibba L. with the order of efficacy being: flavanone > chlorogenic acid > 3,5-O-dicaffeoylquinic acid. Furthermore, when incorporated separately into artificial diet these compounds, at 10 to 1000 ppm, enhanced or reduced growth of the cabbage looper (Trichoplusia ni) and gypsy moth (Lymantria dispar L.). 相似文献
5.
Sex phermone components of mulberry looper,Hemerophila atrilineata butler (lepidoptera: Geometridae)
Zhong-Xing Tan Regine Gries Gerhard Gries Guo-Qiang Lin Guan-Qin Pu Keith N. Slessor Jianxiong Li 《Journal of chemical ecology》1996,22(12):2263-2271
(6Z-9S, 10R)-Epoxy-octadecene (SR-1) and (3Z, 6Z-9S, 10R)-epoxy-octadecadiene (SR-2) are sex pheromone components of the mulberry looper (MBL),Hemerophila atrilineata Butler. Compounds extracted from female MBL pheromone glands were identified by coupled gas chromatographic-electroantennographic detection (GC-EAD) and GC-mass spectrometry. In field experiments in China,SR-2,RS-2, or both combined were hardly attractive, butSR-2 in combination withSR-1 attracted significant numbers of MBL males. Synergistic behavioral activity ofSR-1 plusSR-2, but not of corresponding antipode mixtures, indicates enantiospecificity of MBL pheromone communication. Because blends of racemic and enantiospecific (SR)1 plus2 were similarly attractive, racemic1 plus2 may have potential for mass trapping or confusion of MBL males in commercial mulberry plantations. 相似文献
6.
在热轧带钢其他尺寸精度普遍较高的情况下,宽度控制精度的提升变得越来越重要。提出了一种新的精轧带钢宽度控制综合解决方案:针对带钢头部宽度控制,开发精轧机架冲击速降自学习模型,以减少带钢头部拉窄现象;通过合理配置精轧活套张力稳定因子,减少带钢中部宽度波动现象;通过精轧宽度反馈控制和宽展预测模型修正功能,提高带钢全长宽度精度。相关研究成果已成功应用于宝钢集团某热轧产线三电自主集成改造项目中,改造后带钢宽度控制精度得到显著提高。 相似文献
7.
活套系统控制的好坏,直接影响成品带钢的宽度、厚度等性能指标。活套系统的控制目标是恒定活套量下保持张力波动尽可能小,即降低活套张力控制和高度控制的相互干扰,使系统更加稳定。控制系统能够根据检测到的活套辊摆角的变化,一方面给出控制率去调整上游机架的轧辊速度以保持套量不变;另一方面在带钢轧制过程中,为了保持恒定带钢张力,活套输出的张力矩就必须随着活套角度的不同而相应地改变。针对活套系统非线性、强耦合、多约束等特点,以鞍钢1700热连轧精轧机组为背景,建立了活套系统的动态数学模型。针对该模型提出了一种新型控制策略--单神经元PID与小脑模型复合控制算法来实现活套系统的多变量解耦控制。仿真结果验证了本算法的有效性,其解耦响应速度和抗干扰能力明显优于传统PID解耦控制效果。 相似文献
8.
9.
Jianxiong Li Gerhard Gries Regine Gries Jovo Bikic Keith N. Slessor 《Journal of chemical ecology》1993,19(11):2547-2561
Bakers' yeast reduction of (2E)-3-(2-furanyl)-2-methyl-2-propenal yielded the synthetic intermediate, (2S)-3-(2-furanyl)-2-methylpropanol, of high chiral purity (>97% ee) for the synthesis of the enantiomers of 2,5-dimethylheptadecane and 7-methylheptadecane, two synergistic sex pheromone components of the western hemlock looper (WHL),Lambdina fiscellaria lugubrosa Hulst. In electrophysiological bioassays, (7S)- but not (7R)-7-methylheptadecane elicited strong antennal responses by male WHL antennae. In field trapping experiments, addition of (7S)- but not (7R)-7-methylheptadecane to (5R,11S)-5,11-dimethylheptadecane, the major sex pheromone component of WHL, increased attraction. Attraction to (5R,11S)-5,11-dimethylheptadecane in combination with (7S)-7-methyiheptadecane was further enhanced by the addition of (5S)- but not (5R)-2,5-dimethylheptadecane. Similarly, attraction to (5R,11S)-5,11-dimethylheptadecane combined with (5S)-2,5-dimethylheptadecane increased when 7S- but not (7R)-7-methylheptadecane was added as a third component. We conclude that (7S)-7-methylheptadecane and (5S)-2,5-dimethylheptadecane are the synergistic sex pheromone components of WHL. The synthetic methodology described is applicable to the synthesis of chiral methyl-branched pheromones in other orders of the Insecta, particularly Coleoptera, Diptera and Orthoptera. 相似文献
10.