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61.
In the cheese industry, the concentration of milk using ultrafiltration for continuous soft and fresh cheese production is standard technology. The object of the work presented here was to produce a semi-hard cheese of quality and composition comparable to that of traditionally made cheese from highly concentrated microfiltered milk retentate. Two different membrane systems were tested for the production of high viscous milk retentate with high dry matter content. For milk containing 3.2% fat and skim milk, a concentration factor of 6.6 and 9.1 respectively was obtained using the MF/UF/UF pilot plant fitted with cassette modules. Milk containing 3.2% fat was concentrated in batches by a factor of 5.7 in the pilot plant using a ceramic membrane. Using minimal curd separation, a semi-hard one day old cheese with a dry matter of 533 g/kg, moisture on a fat-free basis (MFFB) of 626 g/kg and fat on a dry basis (FDB) value of 478 g/kg was made from the milk retentate produced with the ceramic module. The ripened cheese fulfilled the legal requirements of a traditionally produced semi-hard cheese with superb sensory qualities. Using the MF/UF/UF plant, a dry matter of 495 g/kg (MFFB 669 g/kg, FDB 493 g/kg) was achieved in a semi-hard cheese made from skim milk retentate. Our results suggest that by using a larger spacer distance in the last loop of the MF/UF/UF plant, combined with new hybrid technologies, semi-hard cheese production from full concentrate milk will soon become possible. 相似文献
62.
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64.
Ulrike Cress Katrin Wodzicki Martina Bientzle Andreas Lingnau 《International Journal of Computer-Supported Collaborative Learning》2011,6(2):307-321
Computer-supported collaborative learning has an unexploited potential of becoming an effective learning method for pupils
with intellectual disabilities. This paper aims at showing how some specific requirements of this target group may be met
by structuring a learning situation with the help of floor control, which restricts the opportunities of a learning dyad to act simultaneously within the learning environment. It was expected
that floor control could improve communication between pupils with intellectual disabilities by explicitly structuring and restricting activities
in the learning environment and making it necessary for the pupils to communicate. To examine if floor control really supports the collaboration process in the hypothesized way, two different versions of a CSCL environment were implemented
and compared. The results revealed improved task-related communication and a higher quality of interaction outcomes. 相似文献
65.
Christian Glaßer Katrin Herr Christian Reitwießner Stephen Travers Matthias Waldherr 《Theory of Computing Systems》2010,46(1):80-103
We investigate the complexity of equivalence problems for {∪,∩,−,+,×}-circuits computing sets of natural numbers. These problems were first introduced by Stockmeyer and Meyer (1973). We
continue this line of research and give a systematic characterization of the complexity of equivalence problems over sets
of natural numbers. Our work shows that equivalence problems capture a wide range of complexity classes like NL, C
=
L, P,Π2P, PSPACE, NEXP, and beyond. McKenzie and Wagner (2003) studied related membership problems for circuits over sets of natural numbers. Our results also have consequences for these membership problems: We provide an
improved upper bound for the case of {∪,∩,−,+,×}-circuits. 相似文献
66.
To increase the fractional energy savings achieved with solar thermal combisystems the store volume may be increased. Installation of large stores in single-family houses is, however, often limited by space constraints. In this article the influence of the store dimensions, as well as internal and external auxiliary volume configurations, are investigated for large solar water stores by annual dynamic TRNSYS simulations. The results show that store sizes up to 4 m3 may be used in solar heating systems with 30 m2 collector area. It is further shown that well-insulated stores are rather insensitive to the geometry. Stores deviating from the conventional dimensions still yield high fractional energy savings. Furthermore, the simulations show that the performance of an internal auxiliary volume configuration in most cases exceeds that of a solution with an external auxiliary unit. The practical limitations of very thin auxiliary volumes must, however, be further investigated. 相似文献
67.
Katrin Borcea-Pfitzmann Marit Hansen Katja Liesebach Andreas Pfitzmann Sandra Steinbrecher 《Datenschutz und Datensicherheit - DuD》2007,31(9):671-675
Interacting in the Internet, users should be empowered to use only those subsets of their personal attributes, called partial
identities, which are appropriate for the actual situation and context. Refraining from acting under few and easily linkable
partial identities is a prerequisite for trustworthy privacy. Traditionally user-controlled identity management systems primarily
support individuals interacting with organisations, but mainly ignore special needs which arise if individuals interact with
each other. To support online communities those systems have to change.
From TU Dresden: Prof. Dr. Andreas Pfitzmann, head of the privacy and security group, and the research assistants Dipl.-Inform. Katrin Borcea-Pfitzmann,
Dipl. Medien-inf. Katja Liesebach and Dipl.-Inform. Sandra Steinbrecher.
From ULD, Kiel: Dipl.-Inform. Marit Hansen, head of PET division.
Research Focus: Privacy in Identity Management and Application Design
This work was funded in part by the PRIME project which receives research funding from the European Union’s Sixth Framework
Programme and the Swiss Federal Office for Education and Science. 相似文献
68.
Reed canary grass (Phalaris arundinacea) is one of the possible raw materials for bioenergy production in northern Europe. Its cultivation is favoured because its high productivity and local origin. However, problems with the biomass quality for combustion have been reported. Usually delayed harvest in spring is suggested to improve the quality and decrease the moisture content of biomass. On the other hand, the feasibility of spring harvest depends on local climatic conditions and may cause yield losses. In current paper we studied reed canary grass fields in Estonia locating on different soil types and cultivated with various varieties. The influence of several fertilisation schemes on biomass yield was analysed. Our results indicated that production was higher on mineral soils than on the organic soil of abandoned peat extraction sites. Even different types of fertilisation did not increase the production on organic soils to the level comparable to those on mineral soils. Among studied varieties ‘Venture’ had the highest production. The highest yield per area was obtained late in the autumn (12.7 t d.w. per ha and 7.2 t d.w. per ha on mineral and organic soils, respectively). By spring the amount of biomass had decreased in all studied sites. Due to wet soil some of the fields remained unharvested, the others had high yield losses during practical harvesting. The chemical analyses did not reveal significant differences in the composition of biomass between late autumn and spring. Therefore we conclude that late autumn harvest should be preferred in local climatic conditions. 相似文献
69.
Zauner T Berger-Hoffmann R Müller K Hoffmann R Zuchner T 《Analytical chemistry》2011,83(19):7356-7363
Proteases are widely used in analytical sciences and play a central role in several widespread diseases. Thus, there is an immense need for highly adaptable and sensitive assays for the detection and monitoring of various proteolytic enzymes. We established a simple protease fluorescence resonance energy transfer (pro-FRET) assay for the determination of protease activities, which could in principle be adapted for the detection of all proteases. As proof of principle, we demonstrated the potential of our method using trypsin and enteropeptidase in complex biological mixtures. Briefly, the assay is based on the cleavage of a FRET peptide substrate, which results in a dramatic increase of the donor fluorescence. The assay was highly sensitive and fast for both proteases. The detection limits for trypsin and enteropeptidase in Escherichia coli lysate were 100 and 10 amol, respectively. The improved sensitivity for enteropeptidase was due to the application of an enzyme cascade, which leads to signal amplification. The pro-FRET assay is highly specific as even high concentrations of other proteases did not result in significant background signals. In conclusion, this sensitive and simple assay can be performed in complex biological mixtures and can be easily adapted to act as a versatile tool for the sensitive detection of proteases. 相似文献
70.
EK Seppet A Kaasik A Minajeva K Paju JJ Ohisalo R Vetter U Braun 《Canadian Metallurgical Quarterly》1998,184(1-2):419-426
This paper discusses the mechanisms of two basic effects of thyroid hormones on atrial responses to beta-adrenergic agonists, i.e. increased inotropic sensitivity and decreased maximal contractile responsiveness. The increased sensitivity of atria to beta-adrenergic agonists under thyroid hormones appears to be related to increases in beta-adrenoceptor density and Gs/Gi protein ratio, leading to activation of Gs-mediated pathway, but suppression of Gi-mediated pathway of adenylate cyclase regulation. Therefore, the i/c concentrations of cAMP and corresponding inotropic responses achieve their maximums at lower doses of beta-adrenergic agonist. Thyroid hormones also decrease the expression of phospholamban, but increase the expression of sarcoplasmic reticulum Ca2+-pump. As a result, the basal activity of sarcoplasmic reticulum Ca2+-pump increases, but its beta-adrenergic activation through phosphorylation of phospholamban decreases. It is suggested that these changes are causal for decreased maximal inotropic and lusitropic responses of atria to beta-adrenergic agonists. 相似文献