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   188篇
  免费   11篇
电工技术   1篇
综合类   5篇
化学工业   102篇
金属工艺   3篇
建筑科学   15篇
轻工业   27篇
水利工程   1篇
无线电   3篇
一般工业技术   27篇
冶金工业   5篇
自动化技术   10篇
  2023年   4篇
  2022年   5篇
  2021年   6篇
  2020年   4篇
  2019年   5篇
  2018年   5篇
  2017年   8篇
  2016年   6篇
  2015年   6篇
  2014年   10篇
  2013年   11篇
  2012年   9篇
  2011年   18篇
  2010年   6篇
  2009年   4篇
  2008年   4篇
  2007年   5篇
  2006年   8篇
  2005年   10篇
  2004年   3篇
  2003年   4篇
  2002年   5篇
  2001年   4篇
  2000年   3篇
  1999年   11篇
  1998年   4篇
  1997年   8篇
  1996年   4篇
  1995年   4篇
  1994年   5篇
  1993年   6篇
  1992年   1篇
  1983年   1篇
  1979年   1篇
  1971年   1篇
排序方式: 共有199条查询结果,搜索用时 31 毫秒
51.
The rubber industry is nowadays facing the general increase of raw materials as the customers are confronted with rising prices for energy. Therefore there is a need for higher durability of elastomer applications. Short fiber reinforced elastomers can contribute to the improvement of dynamic and wear properties. To determine structure–property relationships in short fiber reinforced elastomer compounds it is of crucial interest to know the contributions of fiber aspect ratio, volume content, orientation and fiber–elastomer interaction. Therefore the influence of different processing conditions and fiber contents on the resulting morphology and macroscopic properties was investigated in this article by the help of fluorescence and confocal laser microscopy using a transparent ethylene‐propylene‐diene rubber (EPDM) matrix. It was found that the processing induced fiber breakage was the key factor in determining the composite morphology and subsequent physical properties. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 1682–1690, 2013  相似文献   
52.
53.
Comments on the article of J. S. Phinney (see record 83-36985) about what it means to talk about American ethnic groups. It is suggested that Phinney's advocacy of the combining of the terms ethnicity and race into a single construct in psychology presumes that ethnicity can encompass all aspects of race and culture. But, it is argued here, in psychology and American society at large, ethnicity seemingly has no real meaning apart from its status as a proxy for racial classification or immigrant status, while race has a clear meaning. Drawing on a cursory review of psychology abstracts, it is suggested that it is ill-advised to subsume the better known and more specifically defined construct under the rubric of the fuzzier construct. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
54.
Regine Pfrepper  Gerd Pfrepper 《NTM》2006,14(3):162-173
The aim of the treatise is the proof of educational stays of Russian physicians at the university of Leipzig in the second half of the 19th century. At that time famous scholars of the university of Leipzig like Carl Ludwig, Paul Flechsig,Wilhelm His, Julius Cohnheim and Felix Marchand made an important contribution to the development of physiology, pathology, physiological chemistry and pharmacology.Therefore their institutes were attended by many student trainees.Among them were a lot of Russian physicians too.They went to Leipzig with fellowships from their government to prepare themselves for a professorship in Russia. A bibliography of their experimental works is given.The findings are based on an investigation in German medical magazines.

Wir danken der Deutschen Forschungsgemeinschaft Bonn für die Unterstützung dieser Arbeit, die im Rahmen des Projektes ,,Deutsch-russische Beziehungen in Medizin und Naturwissenschaften im 18. und 19. Jahrhundert“ angefertigt wurde.  相似文献   
55.
Three candidate sex pheromone components, (Z)6,(Z)9-, (Z)6,(E)8-, and (Z)6,(E)9-heneicosadien-11-one (Z6Z9, Z6E8, and Z6E9) were identified in pheromone gland extracts of female Douglas-fir tussock moths (DFTM), Orgyia pseudotsugata (McDunnough). Their occurrence in subnanogram quantities in extracts and structural conversion during analytical procedures and bioassays complicated chemical identifications. Complete identification required comparative analyses of stereoselectively synthesized and female-produced dienones by coupled gas chromatographic–electroantennographic detection (GC-EAD), high-performance liquid chromatography (HPLC) and coupled GC–mass spectrometry (MS). Determination of the pheromone component was contingent upon an experimental design that minimized structural rearrangement of dienones before and during the field test. In a 40-min field experiment, acetonitrile solutions of each of the above dienones were carried on Dry Ice to traps and were syringed onto cotton release devices below trap lids. In combination with the previously known sex pheromone component of DFTM, (Z)6-heneicosen-11-one (Z6), Z6E8 was the only synergistic dienone and the mixture was highly attractive. Because Z6 by itself attracts seven species of tussock moths (two sympatric with DFTM), a blend of Z6 and Z6E8 may impart specificity to DFTM pheromone communication. In commercial lures, this binary blend may facilitate species-specific, sensitive monitoring and efficacious control by mating disruption of this important forest defoliator.  相似文献   
56.
For its high incidence among young men and its affecting male fertility, varicocele requires an accurate screening, as well as an early and definitive treatment. The Authors report their experience in the treatment of varicocele with sclerotherapy: 24 patients underwent sclerotherapy of the left internal spermatic vein with a success rate of 91%. Complications never required hospitalization or surgery. Percutaneous therapy represents thus the treatment of choice in case of varicocele: compared with surgery, it offers similar clinical results and a lower recurrence rate, and it can be performed on an outpatient basis. Surgery should be performed only when anatomic variants make percutaneous treatment not feasible.  相似文献   
57.
(E)-11,13-Tetradecadienal (E11,13–14:Ald) is the major sex pheromone component of the eastern blackheaded budworm (EBB),Acleris variana (Fern.). The compound was identified in female pheromone gland extracts by coupled gas chromatographic-electroantennographic detection (GC-EAD), coupled GC-mass spectrometry in selected ion monitoring mode, and retention index calculations of candidate pheromone components.E11,13–14:Ald alone as trap bait was very attractive to male EBB. Addition of the corresponding diene alcohol or acetate or both did not enhance attraction. (Z)-11,13-Tetradecadienal in binary combination with (E)-11,13–14:Ald neither enhanced nor reduced trap catches. Increasing the amounts of pheromone from 0.01 to 10 µg increased trap catches, but increase of pheromone quantity above 100 µg proportionately reduced attraction. Stabilization of slowly polymerizingE11,13–14:Ald and development of a sustained, adequate release rate is required for pheromone-based monitoring of EBB populations.  相似文献   
58.
Gas chromatographic-electroantennographic detection (GC-EAD) analyses of pheromone extract of female bagworms,Oiketicus kirbyi (Guilding), revealed five EAD-active compounds. Retention index calculations, GC-mass spectrometry in both full-scan and selected-ion monitoring modes and GC-EAD analyses of authentic standards identified the compounds as 1-methylbutyl octanoate (MBO), 1-methylbutyl nonanoate (MBN), 1-methylbutyl decanoate (MBD), 1-methylpentyl decanoate (MPD), and 1-methylbutyl dodecanoate (MBDD). Of these five chiral esters, MBD was most abundant in extracts and elicited the strongest antennal response. In field experiments in Costa Rica, (R)-MBD attractedO. kirbyi males, whereas (S)-MBD in combination with (R)-MBD inhibited response.R but notS enantiomers of MBO, MBN, and MBDD strongly synergized attraction to (R)-MBD. (S)-MBO and (S)-MBDD were inactive, whereas (S)-MBN was inhibitory. (R)-, (S)- and racemic MPD were inactive. Blends of (R)-MBD in ternary combination with either (R)-MBO and (R)-MBN or (R)-MBN and (R)-MBDD were as attractive as the five-ester blend. Five- and four-ester blends were equally attractive, suggesting redundancy of pheromone components for attraction of males. The multiple sex pheromone component blend of chiral esters inO. kirbyi may have evolved to maintain species-specific communication in bagworm communities of tropical Americas.  相似文献   
59.
We tested the hypothesis that males and females of the cherry bark tortrix (CBT), Enarmonia formosana, antennally perceive and behaviorally respond to volatiles from nonhost plants. Volatiles from flowering cherry trees, Prunus serrulata Kwanzan, and from nonhost trees, including trembling aspen, Populus tremuloides, grand fir, Abies grandis, Norway spruce, Picea abies, and Scots pine, Pinus sylvestris, were captured on Porapak Q and extracts analyzed by coupled gas chromatographic–electroantennographic detection (GC-EAD). Compounds that elicited responses from male and female antennae were identified by coupled GC–mass spectrometry (MS) and by comparative GC-MS and GC-EAD with authentic standards. In field cage and field experiments, nonanal from aspen trees and (±)--pinene from coniferous trees were effective in reducing captures of male CBT in pheromone-baited traps and deterring oviposition by female CBT on cherry blocks. Recognition of nonhost volatiles, such as nonanal and -pinene, may allow male and/or female CBT to avoid trees that provide inadequate concealment from predators during calling, resting, and copulation and that are unsuitable for oviposition and development of offspring. Nonhost volatiles may also be exploited for control of CBT by disrupting both mate- and host-finding.  相似文献   
60.
(6Z,9Z,11S)-6,9-Heneicosadien-11-ol (Z6Z9-11S-ol-C21) and (6Z,9Z,11R)-6,9-heneicosadien-11-ol (Z6Z9-11R-ol-C21) were identified as major sex pheromone components of female tussock moths, Orgyia detritaGuérin-Méneville (Lepidoptera: Lymantriidae), on the basis of (1) analyses of pheromone gland extracts of female O. detrita by coupled gas chromatographic-electroantennographic detection (GC-EAD) and GC mass spectrometry, and (2) field trapping experiments with synthetic standards. Z6Z9-11S-ol-C21 and Z6Z9-11R-ol-C21 in combination, but not singly, attracted significant numbers of male moths. Racemic Z6Z9-11-ol-C21 was more attractive than the 1:3.5 (R:S) blend ratio found in pheromone gland extracts from female moths. Lower and higher homologues of Z6Z9-11-ol-C21 were also detected in GC-EAD recordings of pheromone extracts, and the racemic compounds enhanced attractiveness of Z6Z9-11-ol-C21 in field experiments. Because of trace amounts of these homologues in extracts, their enantiomeric composition could not be determined. This is the first report of secondary alcohols as pheromone components in the ditrysian (advanced) Lepidoptera.  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