ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    Electronic Resource
    Electronic Resource
    CNTs/Si〈sub〉3〈/sub〉N〈sub〉4〈/sub〉 Composites Fabricated by Reaction Bonded Processing (2007)
    s.l. ; Stafa-Zurich, Switzerland
    Key engineering materials Vol. 336-338 (Apr. 2007), p. 1277-1279 
    Details
    ISSN: 1013-9826
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: The CNTs/Si3N4 ceramic matrix composites were prepared by the reaction bonded processing.The phase compositions, chemical compatibility, mechanical properties, and microwave attenuationproperties of the composites were investigated. XRD analysis shows the composites consist mainly of theα- and β-Si3N4, with a trace of unreacted silicon. The SEM micrograph displays the fractured surface ofthe composites studs with intact CNTs, indicating that CNTs and Si3N4 are chemically compatible. Thecomposites with 1.0wt.% CNTs have a strength of 280 MPa, hardness of 8.2 GPa and toughness of 2.3MPa·m0.5. The average value of the transmission attenuation reaches 6 dB at X band, indicating thecomposites have a potential for application in electromagnetic adsorbing or shielding
    Type of Medium: Electronic Resource
    URL: http://www.tib-hannover.de/fulltexts/2011/0528/01/53/transtech_doi~10.4028%252Fwww.scientific.net%252FKEM.336-338.1277.pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    Influence of Planetary High-Energy Ball Milling on Microstructure and Mechanical Properties of Silicon Nitride Ceramics (2005)
    Oxford, UK : Blackwell Science Inc
    Journal of the American Ceramic Society 88 (2005), S. 0 
    Details
    ISSN: 1551-2916
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The influence of ball-milling methods on microstructure and mechanical properties of silicon nitride (Si3N4) ceramics produced by pressureless sintering for a sintering additive from MgO–Al2O3–SiO2 system was investigated. For planetary high-energy ball milling, the mechanical properties of Si3N4 ceramics were evidently improved and a homogeneous microstructure developed. In contrast, some exaggerated elongated grains were developed due to the local enrichment of sintering additives in the specimen prepared by general ball milling. For Si3N4 ceramics produced by planetary ball milling, flexure strength of 1.06 GPa, Vickers hardness of 14.2 GPa, and fracture toughness of 6.6 MPa·m0.5 were achieved. The differences in the mechanical properties of Si3N4 ceramics produced by different processing seem to arise mainly from the changes in microstructural homogenization and sinterability. The planetary high-energy ball-milling process provides a good route to mix starting powders for developing ceramics with uniform microstructure and promising mechanical properties.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1551-2916.2005.00227.x
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    Silicon Nitride Films Deposited by Low Pressure Chemical Vapor Deposition from SiH〈sub〉4〈/sub〉-NH〈sub〉3〈/sub〉-N〈sub〉2〈/sub〉 System (2004)
    s.l. ; Stafa-Zurich, Switzerland
    Key engineering materials Vol. 264-268 (May 2004), p. 643-648 
    Details
    ISSN: 1013-9826
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Type of Medium: Electronic Resource
    URL: http://www.tib-hannover.de/fulltexts/2011/0528/01/48/transtech_doi~10.4028%252Fwww.scientific.net%252FKEM.264-268.643.pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 4
    Electronic Resource
    Electronic Resource
    Inspection and feeding of larvae by worker honey bees (Hymenoptera: Apidae): Effect of starvation and food quantity (1991)
    Springer
    Journal of insect behavior 4 (1991), S. 305-317 
    Details
    ISSN: 1572-8889
    Keywords: Honey bee ; Apis mellifera ; feeding ; inspection ; stimulus ; communication
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Honey bee larvae are frequently inspected and, sometimes, provided with food by adult workers, but the stimuli that elicit the important task of food provisioning have never been investigated. Larvae with their food experimentally deprived received more frequent inspection and feeding visits from nurse bees than normally fed larvae, suggesting that there could be a “hunger signal.” Food-deprived larvae with artificially supplied larval food received the same rate of feeding visits from nurse bees as did normally fed larvae but still received more inspection visits. These results suggest that stimuli eliciting feeding are different from those for inspection. They also support the hypothesis that worker bees deposit food in a larval cell only when the quantity of food is below a certain minimum threshold that is perceived during larval inspections. A model is presented regarding the stimuli from larvae that result in worker feeding behavior.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01048280
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 5
    Electronic Resource
    Electronic Resource
    Nonrandom visitation of brood cells by worker honey bees (Hymenoptera: Apidae) (1991)
    Springer
    Journal of insect behavior 4 (1991), S. 177-184 
    Details
    ISSN: 1572-8889
    Keywords: honey bee ; Apis mellifera ; brood signal ; communication
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The visitation pattern by worker honey bees to cells in the brood nest was monitored on an artificially created brood pattern consisting of about one-fourth brood cells evenly distributed among empty cells. The majority (63 %) of the observed workers selectively entered larval cells. In contrast, some workers avoided egg cells when presented a choice of egg vs empty cells. The results suggest that larvae produce a general signal indicating their presence to worker bees. Eggs also seem to produce a signal, which is perceived to be different from the one from larvae.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01054610
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 6
    Electronic Resource
    Electronic Resource
    Regulation of honey bee division of labor by colony age demography (1996)
    Springer
    Behavioral ecology and sociobiology 39 (1996), S. 147-158 
    Details
    ISSN: 1432-0762
    Keywords: Key words Age demography ; Behavioral development ; Behavioral plasticity ; Juvenile hormone ; Temporal polyethism
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The age at which worker honey bees begin foraging varies under different colony conditions. Previous studies have shown that juvenile hormone (JH) mediates this behavioral plasticity, and that worker-worker interactions influence both JH titers and age at first foraging. These results also indicated that the age at first foraging is delayed in the presence of foragers, suggesting that colony age demography directly influences temporal division of labor. We tested this hypothesis by determining whether behavioral or physiological development can be accelerated, delayed, or reversed by altering colony age structure. In three out of three trials, earlier onset of foraging was induced in colonies depleted of foragers compared to colonies depleted of an equal number of bees across all age classes. In two out of three trials, delayed onset of foraging was induced in colonies in which foragers were confined compared to colonies with free-flying foragers. Finally, in three out of three trials, both endocrine and exocrine changes associated with reversion from foraging to brood care were induced in colonies composed of all old bees and devoid of brood; JH titers decreased and hypopharyngeal glands regenerated. These results demonstrate that plasticity in age-related division of labor in honey bee colonies is at least partially controlled by social factors. The implications of these results are discussed for the recently developed ‘‘activator-inhibitor” model for honey bee behavioral development.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002650050276
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 7
    Electronic Resource
    Electronic Resource
    Division of labor between undertaker specialists and other middle-aged workers in honey bee colonies (1997)
    Springer
    Behavioral ecology and sociobiology 41 (1997), S. 151-163 
    Details
    ISSN: 1432-0762
    Keywords: Key wordsApis mellifera ; Division of labor ; Honey bees ; Social insects ; Ergonomics ; Hygienic behaviour
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A primary determinant of colony organization in temporally polyethic insect societies is inter-individual variation in behavior that is independent of worker age. We examined behavioral repertoires, behavioral correlates of adult development, and spatial distributions within the hive to explore the mechanisms that produce behavioral variation among middle-age honey bees (Apis mellifera). Individually labeled undertakers, guards, food storers, and wax workers exhibited a broad range of task-related behavior, but bees tagged as undertakers were more likely to subsequently remove a corpse from the hive and handle a corpse compared to other middle-aged bees. The activity level of undertakers was similar to other task groups, suggesting that undertaking specialists were neither hyper-active “elites” nor quiescent “reserves” that become active only when a dead bee stimulus is present. Undertakers also were more likely to remove debris and to remain in the lower region of the hive or near the entrance, even when not engaged in corpse removal; both preferences may promote colony efficiency by reducing inter-task travel times. Guards and undertakers were less likely to perform behavior normally associated with young bees compared to food storers and wax workers. Undertakers and guards also initiated foraging at earlier ages than the other task groups. These results suggest that undertakers and guards may be slightly developmentally advanced compared to food storers and wax workers. There also was evidence for lifetime differences in behavioral preferences which could not be explained by differences in adult development. Bees tagged as undertakers were more likely to subsequently remove a dead bee during their entire pre-foraging career compared to other task groups or members of their general age cohort. Differences in both the rate of adult development and individual behavioral preferences, both of which may be subject to genetic and environmental influences, are important determinants of inter-individual variation among honey bees of middle age.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002650050374
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 8
    Electronic Resource
    Electronic Resource
    Effects of colony food shortage on behavioral development in honey bees (1998)
    Springer
    Behavioral ecology and sociobiology 42 (1998), S. 295-303 
    Details
    ISSN: 1432-0762
    Keywords: Key words Temporal polyethism ; Behavioral development ; Behavioral plasticity ; Foraging behavior ; Division of labor
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Three experiments were conducted to explore the effects of severe food shortage on the control of two important and interrelated aspects of temporal division of labor in colonies of the honey bee (Apis mellifera): the size and age distribution of a colony's foraging force. The experiments were conducted with single-cohort colonies, composed entirely of young bees, allowing us to quickly distinguish the development of new (precocious) foragers from increases in activity of bees already competent to forage. In experiment 1, colony food shortage caused an acceleration of behavioral development; a significantly greater proportion of bees from starved colonies than from fed colonies became precocious foragers, and at significantly younger ages. Temporal aspects of this starvation effect were further explored in experiment 2 by feeding colonies that we initially starved, and starving colonies that we initially fed. There was a significant decrease in the number of new foragers in starved colonies that were fed, detected 1 day after feeding. There also was a significant increase in the number of new foragers in fed colonies that were starved, but only after a 2-day lag. These results suggest that colony nutritional status does affect long-term behavioral development, rather than only modulate the activity of bees already competent to forage. In experiment 3, we uncoupled the nutritional status of a colony from that of the individual colony members. The behavior of fed individuals in starved colonies was indistinguishable from that of bees in fed colonies, but significantly different from that of bees in starved colonies, in terms of both the number and age distribution of foragers. These results demonstrate that effects of starvation on temporal polyethism are not mediated by the most obvious possible worker-nest interaction: a direct interaction with colony food stores. This is consistent with previous findings suggesting the importance of worker-worker interactions in the regulation of temporal polyethism in honey bees as well as other social insects.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002650050442
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 9
    facet.materialart.
    Unknown
    H15221. New ent-Pimarane Diterpenes from the Roots of Aralia dumetorum (2016)
    Wiley
    Details
    Publication Date: 2016-02-23
    Description: Four new ent -pimarane diterpenes were isolated from the ethanol extract of Aralia dumetorum , together with three known compounds involving ent -pimar-8 (14),15-dien-19-oic acid (5), ent -pimar - 8 (14), 15-dien-19-ol (6), ent -kaur-16-en-19-oic acid (7). By detailed analyses of the MS, IR, and NMR data, the structures of four new diterpenes were characterized as (5 β ,9 β ,10 α ,13 α )-Pimara-6,8(14),15-trien-18-oic acid (1), (5 β ,7 β ,9 β ,10 α ,13 α )-7-methoxypimara-8(14),15-dien-18-oic acid (2), (5 β ,9 β ,10 α ,13 α ,14 β )-14-methoxypimara-7,15-dien-18-oic acid (3) and (5 β ,10 α ,13 α ,14 α )-14-hydroxypimara-7,9(11),15-trien-18-oic acid (4). The cytotoxic activities of compounds 1-7 were assayed in vitro through MTT method. This article is protected by copyright. All rights reserved.
    Print ISSN: 0018-019X
    Electronic ISSN: 1522-2675
    Topics: Chemistry and Pharmacology
    Published by Wiley
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 10
    facet.materialart.
    Unknown
    Detection of malachite green in fish based on magnetic fluorescent probe of CdTe QDs/nano-Fe 3 O 4 @MIPs (2018)
    Elsevier
    Details
    Publication Date: 2018-05-01
    Print ISSN: 1386-1425
    Electronic ISSN: 1873-3557
    Topics: Chemistry and Pharmacology , Physics
    Published by Elsevier
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...