全文获取类型
收费全文 | 230篇 |
免费 | 10篇 |
专业分类
电工技术 | 3篇 |
化学工业 | 93篇 |
金属工艺 | 3篇 |
建筑科学 | 5篇 |
矿业工程 | 1篇 |
能源动力 | 3篇 |
轻工业 | 25篇 |
水利工程 | 1篇 |
石油天然气 | 5篇 |
无线电 | 9篇 |
一般工业技术 | 27篇 |
冶金工业 | 50篇 |
原子能技术 | 7篇 |
自动化技术 | 8篇 |
出版年
2024年 | 1篇 |
2023年 | 1篇 |
2022年 | 3篇 |
2021年 | 2篇 |
2020年 | 1篇 |
2018年 | 4篇 |
2017年 | 7篇 |
2016年 | 4篇 |
2015年 | 2篇 |
2014年 | 19篇 |
2013年 | 11篇 |
2012年 | 7篇 |
2011年 | 5篇 |
2010年 | 7篇 |
2009年 | 7篇 |
2008年 | 16篇 |
2007年 | 7篇 |
2006年 | 14篇 |
2005年 | 2篇 |
2004年 | 6篇 |
2003年 | 7篇 |
2002年 | 3篇 |
2001年 | 2篇 |
2000年 | 2篇 |
1999年 | 4篇 |
1998年 | 13篇 |
1997年 | 2篇 |
1996年 | 3篇 |
1995年 | 1篇 |
1994年 | 4篇 |
1993年 | 5篇 |
1992年 | 1篇 |
1991年 | 3篇 |
1990年 | 1篇 |
1989年 | 7篇 |
1988年 | 2篇 |
1987年 | 10篇 |
1986年 | 5篇 |
1985年 | 4篇 |
1984年 | 6篇 |
1982年 | 3篇 |
1981年 | 3篇 |
1980年 | 2篇 |
1979年 | 4篇 |
1978年 | 5篇 |
1977年 | 4篇 |
1976年 | 3篇 |
1975年 | 5篇 |
排序方式: 共有240条查询结果,搜索用时 15 毫秒
71.
Previously, (Z)-11-tetradecen-1-yl acetate was reported as the sex pheromone of the obliquebanded leafroller,Choristoneura rosaceana (Harris). A mixture of 92% (Z)-11-tetradecen-1-yl acetate and 8% (E)-tetradecen-1-yl acetate has been reported as an attractant for this insect. (E)-11-tetradecen-1-yl acetate and (Z)-11-tetradecen-1-ol have now been isolated and identified from female tip extracts and shown to be behaviorally active; in addition, there is some evidence for the presence of (E)-11-tetradecen-1-ol in these extracts. TheZE ratio for both the acetates and the alcohols in these tip extracts was about 982; the proportion of alcohols was rather variable, but the acetates always predominated. Maximum trap catches fn the field during the course of this study were obtained with 5 mg of 955 (Z)(E)-11-tetradecen-1-yl acetates containing 0.5–10% (Z)-11-tetradecen-1-ol (approx. 1%Eisomer) in polyethylene caps. No evidence was found for the presence of (Z)-11-tetradecenal in female tip extracts, and this compound was found to be ineffective in increasing trap catches.Lepidoptera: Tortricidae: Tortricinae.This research was supported in part by the Rockefeller Foundation, and by NSF Grant No. GB-38020. 相似文献
72.
According to most models of speech production, the planning of spoken words involves the independent retrieval of segments and metrical frames followed by segment-to-frame association. In some models, the metrical frame includes a specification of the number and ordering of consonants and vowels, but in the word-form encoding by activation and verification (WEAVER) model (A. Roelofs, 1997), the frame specifies only the stress pattern across syllables. In 6 implicit priming experiments, on each trial, participants produced 1 word out of a small set as quickly as possible. In homogeneous sets, the response words shared word-initial segments, whereas in heterogeneous sets, they did not. Priming effects from shared segments depended on all response words having the same number of syllables and stress pattern, but not on their having the same number of consonants and vowels. No priming occurred when the response words had only the same metrical frame but shared no segments. Computer simulations demonstrated that WEAVER accounts for the findings. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
73.
74.
Diuk-Wasser MA Dolo G Bagayoko M Sogoba N Toure MB Moghaddam M Manoukis N Rian S Traore SF Taylor CE 《International journal of remote sensing》2006,27(3):535-548
We explored the use of the European Remote Sensing Satellite 2 Synthetic Aperture Radar (ERS-2 SAR) to trace the development of rice plants in an irrigated area near Niono, Mali and relate that to the density of anopheline mosquitoes, especially An. gambiae. This is important because such mosquitoes are the major vectors of malaria in sub-Saharan Africa, and their development is often coupled to the cycle of rice development. We collected larval samples, mapped rice fields using GPS and recorded rice growth stages simultaneously with eight ERS-2 SAR acquisitions. We were able to discriminate among rice growth stages using ERS-2 SAR backscatter data, especially among the early stages of rice growth, which produce the largest numbers of larvae. We could also distinguish between basins that produced high and low numbers of anophelines within the stage of peak production. After the peak, larval numbers dropped as rice plants grew taller and thicker, reducing the amount of light reaching the water surface. ERS-2 SAR backscatter increased concomitantly. Our data support the belief that ERS-2 SAR data may be helpful for mapping the spatial patterns of rice growth, distinguishing different agricultural practices, and monitoring the abundance of vectors in nearby villages. 相似文献
75.
76.
P. J. Silk L. P. S. Kuenen S. H. Tan W. L. Roelofs C. J. Sanders A. R. Alford 《Journal of chemical ecology》1985,11(2):159-167
Chemical identification and field-trapping experiments have shown that a blend of 8515 (E,Z)-11-tetradecenyl acetates and 8515 (E,Z)-11-tetradecen-1-ols (in a 91 ratio) are female sex pheromone components for jack pine budworm,Choristoneura pinus pinus. This blend of chemicals, formulated in PVC (0.1 %, w/w) sources is as effective a trap bait as virgin females. Preliminary wind tunnel observations have indicated that this blend, effective as a trap bait, is not equivalent to females.Lepidoptera: Tortricidae. 相似文献
77.
C. E. Linn Jr. L. B. Bjostad J. W. Du W. L. Roelofs 《Journal of chemical ecology》1984,10(11):1635-1658
The flight response of maleTrichoplusia ni was observed in a flight tunnel to a sex pheromone blend composed of six components:Z7–12Ac, 12Ac,Z5-12Ac, 11-12Ac,Z7-14Ac, and Z9-14Ac. The number of males reaching a 3000-g source of this blend was > 95%, equal to that observed to female glands and significantly greater than with the previously identified two-component blend (Z7-12Ac + 12Ac). In subtraction tests, all five-component blends, with the exception of the blend lacking the primary componentZ7-12Ac, and several four-component blends elicited similar peak levels of upwind flight, source contacts, and hairpencil displays to that observed with the six-component blend. We characterize the substitution of certain minor components for one another as a form of redundancy in the chemical signal and suggest that it contributes to response specificity and signal recognition in males. The results also support the concept that the full blend of components acts as a unit to influence male behavior at all phases of the response. Individual minor components were not responsible for eliciting specific behaviors in the sequence. 相似文献
78.
The design, construction, and uses of a relatively simple and inexpensive wind tunnel for studying responses of flying insects to sex pheromones are presented with special reference to research on moths. A variable-speed continuous belt installed on the tunnel floor proved to be a valuable feature, allowing the observer to manipulate the speed of the responding insect and thus to measure the duration and persistence of sustained anemotactic flights in the pheromone plume. It is concluded that flight tunnels of this kind will prove to be extremely valuable multipurpose tools in pheromone research. 相似文献
79.
Widmanstätten ferrite plate formation in low-carbon steels 总被引:1,自引:0,他引:1
The mechanism by which Widmanstätten ferrite plates nucleate and grow in low-carbon steels has been studied. In-situ laser scanning confocal microscopy (LSCM) observations, optical microscopy, and electron backscattered diffraction (EBSD) techniques have been used to characterize the relationship between grain boundary allotriomorphs and Widmanstätten ferrite plates. The issue of where Widmanstätten ferrite plates nucleate is one of some debate, with theories including morphological instability and sympathetic nucleation. Evidence has been found that supports the theory of a sympathetic nucleation mechanism being responsible for the formation of Widmanstätten ferrite plates. The EBSD measurements have shown that low-angle misorientations of between 5 and 10 deg exist between ferrite allotriomorphs and Widmanstätten ferrite plates. 相似文献
80.
Dominic Phelan Bao Jiang Xu Rian Dippenaar 《Materials Science and Engineering: A》2006,420(1-2):144-149
A study has been conducted to probe the formation of intermetallic phases on steel substrates immersed in 55 wt.%Al–Zn–Si hot dip baths as a function of dipping time and bath silicon content. Two bath compositions containing 1.3 and 1.5 wt.% Si, respectively, combined with two immersion times of 3 and 9 s were studied. It was found that the reaction rate and intermetallic phase formation varied in response to silicon content. Optical microscopy revealed a quantifiable difference in the development of the reaction layer between the two bath compositions. SEM-EDS revealed that the reaction layer that evolved on samples dipped in the 1.5 wt.% silicon bath were comprised of two intermetallic species, -AlFeSi/Fe2Al5, whilst in the 1.3 wt.% bath there were three clearly identifiable intermetallic species -AlFeSi/FeAl3/Fe2Al5. A fourth phase appeared to be present in samples immersed in the 1.3 wt.% Si bath that, due to its fine structure, could not be conclusively identified. Experimental results from the literature and from this study have been assessed with reference to the phase stability predicted by MTDATA, a thermodynamic modelling package. 相似文献