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31.
Electrical equipment for a cement plant should be placed in rooms for protection of the equipment itself and to avoid unauthorized persons from coming in contact with the equipment. Electrical equipment generates heat, and this heat must be dissipated in order to maintain the ambient temperature within the proper limits. There is also a possibility of electrical fires due to faults in the electrical equipment, and steps must be taken to prevent fire from spreading throughout the room and the rest of the facility. Some of the recommendations reflect the typical approach used in Germany and may not necessarily be used in the United States. 相似文献
32.
A new colorimetric method to quantify β-1,3-1,6-glucans in comparison with total β-1,3-glucans in edible mushrooms 总被引:2,自引:0,他引:2
Jörg Nitschke Hendrik Modick Ekkehard Busch Reimund Wantoch von Rekowski Hans-Josef Altenbach Helga Mölleken 《Food chemistry》2011
Mushroom β-glucans are known for their activity as biological response modifiers and anticarcinogenic agents. β-1,3-1,6 Branched glucans with a triple helix tertiary structure are recognised as the most potent ones. In the present work, a colorimetric method for β-1,3-1,6-glucan quantification based on the dye Congo red is introduced. This method is specific for β-glucans with a triple helix. The β-1,3-1,6-glucan content of mycelia and fruiting bodies from various mushrooms was determined and compared with the total β-1,3-glucan content, measured by a fluorimetric method. The results show equal amounts of β-1,3-1,6- and total β-1,3-glucans in the analysed species but obvious differences between mycelia and fruiting bodies. On the average, 3% of mycelia and 8% of fruiting body dry mass consist of β-1,3-1,6-glucans. The average percentage of β-1,3-1,6-glucans in the total β-1,3-glucan content differs between mycelia (46%) and fruiting bodies (87%). 相似文献
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The initial slope of the time-dependent scattering function and the static structure factor S(q) of macromolecules in good solvents are calculated without using the Gaussian assumption. For S(q), the scaling relation S(q)~q?1.7 is confirmed in the intermediate q range, whereas no q dependent cross-over behaviour can be observed. The calculation of reveals a q3 dependence in this range and no evidence is seen for an exponent apart from 3. The time-dependent scattering function S(q,t) is treated within the framework of the Gaussian assumption. Hydrodynamic as well as excluded volume interactions are incorporated. It has been found that excluded volume effects decrease the decay of the scattering function in comparison with the Gaussian chain. 相似文献
36.
Andrea Hund Ekkehard Ramm 《International journal for numerical methods in engineering》2007,70(13):1613-1632
This paper presents a two‐scale approach for the mechanical and numerical modelling of materials with microstructure‐like concrete or fibre‐reinforced concrete in the non‐linear regime. It addresses applications, where the assumption of scale separation as the basis for classical homogenization methods does not hold. This occurs when the resolution of micro and macro scale does not differ ab initio or when evolving fluctuations in the macro‐fields are in the order of the micro scale during the loading progress. Typical examples are localization phenomena. The objective of the present study is to develop an efficient solution method exploiting the physically existing multiscale character of the problem. The proposed method belongs to the superposition‐based methods with local enrichment of the large‐scale solution ū by a small‐scale part u ′. The main focus of the present formulation is to allow for locality of the small‐scale solution within the large‐scale elements to achieve an efficient solution strategy. At the same time the small‐scale information exchange over the large‐scale element boundaries is facilitated while maintaining the accuracy of a refined complete solution. Thus, the emphasis lies on finding appropriate locality constraints for u ′. To illustrate the method the formulation is applied to a damage mechanics based material model for concrete‐like materials. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
37.
Improving field performance of telecommunication systems is the key objective of both telecom suppliers and operators, as
an increasing amount of business critical systems worldwide are relying on dependable telecommunication. Early defect detection
improves field performance in terms of reduced field failure rates and reduced intrinsic downtime. This paper describes an
integrated approach to improve early defect detection and thus field reliability of telecommunication switching systems. The
assumptions at the start of the projects discussed in this paper are: Wide application of code inspections and thorough module
testing must lead to a lower fault detection density in subsequent phases. At the same time criteria for selecting the most
critical components for code reviews, code inspections and module test are provided in order to optimize efficiency. The primary
goal is to identify critical components and to make failure predictions as early as possible during the life cycle and hence
reduce managerial risk combined with too early or too late release of such a system to the field. During test release time
prediction and field performance prediction are both based on tailored and superposed ENHPP reliability models. Experiences
from projects of Alcatel’s Switching and Routing Division are included to show practical impacts.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
38.
Ahmed El‐Hadi Rainer Schnabel Ekkehard Straube Gert Müller M. Riemschneider 《大分子材料与工程》2002,287(5):363-372
Poly(3‐hydroxybutyrate) (PHB) is sensitive to high processing temperatures. This leads to a decrease in molar mass as well as a lower melt viscosity. The crystallization temperature shifts to lower values, and crystallization kinetics is slow. A mixture was developed in order to improve the manufacturing properties and the final product. The blends exhibit a slight reduction in molar mass because they have a lower melting point than pure PHB, and can be extruded at their melt temperature of 170 to 180°C. Then they immediately crystallize at 125 to 100°C. Differential scanning calorimetry (DSC) shows the effect of holding time in the melt on crystallization behavior. It has been shown that the crystallization time has to be longer in the case of PHB and shorter for the blends. Thermal degradation of PHB and its blends has been investigated using thermogravimetry analysis (TG). Derivative thermogravimetry coupled with TG (TG/DTG) curves show three decomposition stages for blends at 290, 340 and 445°C, respectively. Acetic acid, water, carbon dioxide and methane are produced by degradation at a higher temperature. 相似文献
39.
Ming Zhao Chao Wang Min Guo Shiqi Peng Ekkehard Winterfeld 《Advanced Synthesis \u0026amp; Catalysis》1999,341(7):691-694
In the presence of Na2CO3 (1S,3S)‐ and (1R,3S)‐1‐(2,2‐dimethoxyethyl)‐2‐(1,3‐dioxobutyl)‐3‐(1,3‐dioxo‐butyl)oxymethyl‐1,2,3,4‐tetrahydrocarboline ( 1 ) were transformed into (1S,3S)‐ and (1R,3S)‐1‐(2,2‐dimethoxyethyl)‐2‐(1,3‐dioxobutyl)‐3‐hydroxymethyl‐1,2,3,4‐tetrahydrocarboline ( 2 ), which were cyclized to (6S)‐3‐acetyl‐6‐hydroxymethyl‐4,6,7,12‐tetrahydro‐4‐oxoindolo[2,3‐a]quinolizine ( 4 ), via(6S,12bS)‐ and (6S,12bR)‐3‐acetyl‐2‐hydroxyl‐6‐hydroxymethyl‐1,2,3,4,6,7,12,12b‐octahydro‐4‐oxoindolo[2,3‐a]quinoline ( 3 ). (6S)‐ 4 was coupled with Boc‐Gly, Boc‐L‐Asp(β‐benzyl ester), or Boc‐L‐Gln to give 6‐amino acid substituted (6S)‐3‐acetyl‐4,6,7,12‐tetrahydro‐4‐oxoindolo[2,3‐a]quinolizines 5a , 5b , or 5c , respectively. After the removal of Boc from (6S)‐ 5a (6S)‐3‐acetyl‐6‐glycyl‐4,6,7,12‐tetrahydro‐4‐oxoindolo[2,3‐a]quinolizine ( 6 ) was obtained. The anticancer activities of (6S)‐ 5 and (6S)‐ 6 in vitro were tested. 相似文献
40.