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1.
Each amino acid is represented by a vector of numerical measurements for the attributes of volume, area, hydrophilicity, polarity, hydrogen bonding, shape, and charge. Inter-residue distances are then calculated according to common metrics, and we introduce a new clustering objective function derived from information-theoretic considerations. The arguments of the function are the inter-object distances of the things to be clustered: in this case the amino acids. By means of approximating the solution of an integer programming problem, then, the residues are partitioned into clusters. The clusters obtained are compared with groups obtained in substitution/mutation studies and found to be similar. Thus, probably the strongest and most objective evidence to date is supplied for believing that physico-chemical properties account for the viability of substitutions and that the important similarities/differences are explained by a relatively small and simple set of properties.  相似文献   
2.
The click beetle species Agriotes acuminatus is distributed in open deciduous forests throughout a large area in Europe. In order to identify its sex pheromone, gland extracts of female beetles were investigated by using GC/MS. Neryl butanoate and 2,6-dimethyl-(Z,E)-2,6-octadien-1,8-diol dihexanoate, in a ratio of approximately 1:5, were the only volatile compounds present in the extracts. Structures of both esters were confirmed by synthesis. Field experiments revealed a strong attraction of A. acuminatus males towards neryl butanoate, which could be synergistically enhanced by addition of 2,6-dimethyl-(Z,E)-2,6-octadien-1,8-diol dihexanoate. The latter compound alone did not show any attractive effect. While all Agriotes spp. investigated to date use geranyl and/or (E,E)-farnesyl esters as sex pheromones, the nerol derivatives of A. acuminatus are the first (Z)-2-configurated pheromones within this genus.  相似文献   
3.
Research has shown that colours influence motivation and cognitive performance. In achievement contexts, red evokes avoidance motivation that hinders creativity, while blue elicits an approach motivation that facilitates creativity. However, due to their position and mode of presentation, colours may convey a different message. Red accent lighting creates a cosy, friendly room atmosphere that may, even in an achievement context, elicit an approach rather than an avoidance motivation. Results (N = 146) showed that both blue and red accent light increased strategic approach motivation compared to white accent light. Moreover, through the heightened approach motivation, colourful accent light indirectly improved creative performance. Implications for future research on colour and practical implications for colour usage are discussed.

Practitioner Summary: Designing work environments for creativity is a new topic in ergonomics research and practice. The present study demonstrates indirect effects of coloured accent light on creativity providing interesting possibilities for the design of workplaces for knowledge workers, classrooms and all other rooms in which people work on new ideas.  相似文献   

4.
Laser-based pre-heating of laser beam welding with a 3D scanning optics, applied to AISI 1045 steel, is studied. Laser beam welding of heat-treatable steel is challenging due to martensitic hardening in combination with defects. Pre-tempering aims the reduction of the cooling rates and martensitic microstructure within the weld seam. An oscillating defocused laser beam was guided over the surface for pre-heating by means of a 3D scanner optics. During pre-heating, the laser power, the scanning speed and the number of cycles were varied. Welding with 4000 W and 2 m/min with a focused laser beam was executed. Thus the resulting temperature profile behind the ongoing laser beam and cooling time T8|5 between 800 °C–500 °C was significantly extended. Two parameter combinations (15 cycles|600 W|50 mm/s(2) and 10 cycles|800 W|50 mm/s2) succeeded in a microstructure of bainite and martensite. By extending the cooling time T8|5 to 3.11 s(2) and 4.17 s2. Thus, average hardness for laser based pre-tempering of 487 HV 0.5(2) and 455 HV 0.52 was achieved. As a reference, global pre-heating at 400 °C using a heating plate can reduce the average hardness of the weld zone from 729 HV 0.5 at room temperature to 304 HV 0.5 at a cooling time T8|5 of 5.63 s.  相似文献   
5.
Males and females of the parasitic wasp Lariophagus distinguendus respond to volatiles emitted by the larval faeces of one of their hosts, the granary weevil Sitophilus granarius. Previous studies have shown that attractive chemicals are emitted by astigmatid mites living in the host faeces and that these cues are attractive only to experienced parasitoids. In the present study we demonstrate that larval faeces of the host and headspace extracts of the faeces are attractive for both sexes of the parasitoid even when the mites were experimentally excluded from the beetle rearings. The response to volatiles from mite-free host faeces is innate. In order to elucidate the chemistry of this odor, headspace extracts were fractionated by adsorption chromatography. Tests using combinations of fractions of different polarities revealed that both the non-polar pentane and the polar methanol fractions were necessary to maintain the attractiveness. This indicates that the attractive odor is composed of a complex blend of components with different polarities. The composition of the polar fraction was analyzed by gas chromatography-mass spectrometry, whereas elucidation of the structure of non-polar components has not been possible so far. By orientating toward the same host-related volatiles used by females for host finding, L. distinguendus males may be arrested in patches of potentially high female density and thus increase their chance of mating.  相似文献   
6.
7.
We introduce a prototype flying platform for planetary exploration: autonomous robot design for extraterrestrial applications (ARDEA). Communication with unmanned missions beyond Earth orbit suffers from time delay, thus a key criterion for robotic exploration is a robot's ability to perform tasks without human intervention. For autonomous operation, all computations should be done on‐board and Global Navigation Satellite System (GNSS) should not be relied on for navigation purposes. Given these objectives ARDEA is equipped with two pairs of wide‐angle stereo cameras and an inertial measurement unit (IMU) for robust visual‐inertial navigation and time‐efficient, omni‐directional 3D mapping. The four cameras cover a 24 0 ° vertical field of view, enabling the system to operate in confined environments such as caves formed by lava tubes. The captured images are split into several pinhole cameras, which are used for simultaneously running visual odometries. The stereo output is used for simultaneous localization and mapping, 3D map generation and collision‐free motion planning. To operate the vehicle efficiently for a variety of missions, ARDEA's capabilities have been modularized into skills which can be assembled to fulfill a mission's objectives. These skills are defined generically so that they are independent of the robot configuration, making the approach suitable for different heterogeneous robotic teams. The diverse skill set also makes the micro aerial vehicle (MAV) useful for any task where autonomous exploration is needed. For example terrestrial search and rescue missions where visual navigation in GNSS‐denied indoor environments is crucial, such as partially collapsed man‐made structures like buildings or tunnels. We have demonstrated the robustness of our system in indoor and outdoor field tests.  相似文献   
8.

Agriotes pilosellus is a fairly common click beetle species distributed in open deciduous and mixed forests throughout a large area in Europe. To identify its sex pheromone, gland extracts of female beetles were analyzed using gas chromatography-mass spectrometry (GC-MS). The only volatile compounds present in the extracts were geranyl butanoate and (E)-8-hydroxygeranyl dibutanoate in a 1:3 ratio, identified by comparison with synthetic samples. Field experiments revealed a clear attraction of A. pilosellus - males towards traps baited with geranyl butanoate, which could be synergistically enhanced by the factor of almost ten by addition of (E)-8-hydroxygeranyl dibutanoate. The latter compound alone did not show any attractive effect. Both compounds correspond well to the structures known from other Agriotes species and may serve as an effective monitoring tool for entomofaunistic research.

  相似文献   
9.
The parasitic wasp, Cephalonomia tarsalis (Hymenoptera: Bethylidae), parasitizes larvae of the sawtoothed grain beetle, Oryzaephilus surinamensis (L.) (Coleoptera: Silvanidae), and is used for biological control of this worldwide pest of stored grain. To study the hypothesis that C. tarsalis not only mates at its natal patch but also uses olfactory cues to find mating partners elsewhere, we investigated semiochemical use by male C. tarsalis. Olfactometer experiments revealed that male C. tarsalis are arrested by odors emanating from the cocoons of conspecifics, from young unmated females, and from feces of the host. Dodecanal, which was identified from extracts of filter paper contaminated by young females, had an arresting effect on males but not on females and was, therefore, considered as a sex pheromone. These findings indicate that C. tarsalis is a species with partial local mate competition. Males mate with females: 1) at the emergence site following location of females by sex pheromones from their cocoons, and 2) after dispersal from the natal patch following location of females directly by dodecanal and indirectly by unidentified sexual kairomones from host feces.  相似文献   
10.
Deposition, turnover and movement of persistent organic pollutants (POP) were investigated in the EU integrated project "AquaTerra", which is among the first funded environmental projects within the 6th Framework Program by the European Commission. Project work integrates across various disciplines that range from biogeochemistry, environmental engineering, computer modelling and chemistry to socio-economic sciences. Field study areas are the river basins of the Ebro, the Meuse, the Elbe and the Danube as well as the 3-km(2) French catchment of the Brévilles Spring. Within the first 2 years of the project more than 1700 samples of atmospherically deposited particles, sediments, and water have been collected in the above-mentioned systems. Results show clear spatial patterns of deposition of polyaromatic hydrocarbons (PAHs) with the highest rates in the Meuse Basin. For local inputs, in the Brévilles sandy aquifer, the contamination of the groundwater by the pesticides atrazine (AT) and deethylatrazine did not decrease even 5 years after their agricultural inputs were stopped. On the other hand, herbicides such as mecroprop (MCPP), and PAHs, were at least partially degraded microbiologically in laboratory studies with soils and aquifer material from selected sites. For sediment transport of contaminants, new flood sampling techniques revealed highest deposition rates of beta-hexachlorocyclohexane (beta-HCH) in river sediments at hotspot areas on the Mulde River in the Bitterfeld region (Elbe Basin, Germany). These selected preliminary results of AquaTerra help to improve fundamental understanding of persistent organic pollutants (POP) in the environment.  相似文献   
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