全文获取类型
收费全文 | 1563篇 |
免费 | 83篇 |
国内免费 | 3篇 |
专业分类
电工技术 | 26篇 |
综合类 | 9篇 |
化学工业 | 627篇 |
金属工艺 | 41篇 |
机械仪表 | 19篇 |
建筑科学 | 46篇 |
矿业工程 | 4篇 |
能源动力 | 34篇 |
轻工业 | 329篇 |
水利工程 | 6篇 |
石油天然气 | 3篇 |
无线电 | 68篇 |
一般工业技术 | 237篇 |
冶金工业 | 60篇 |
原子能技术 | 7篇 |
自动化技术 | 133篇 |
出版年
2024年 | 5篇 |
2023年 | 28篇 |
2022年 | 139篇 |
2021年 | 197篇 |
2020年 | 46篇 |
2019年 | 57篇 |
2018年 | 66篇 |
2017年 | 57篇 |
2016年 | 61篇 |
2015年 | 53篇 |
2014年 | 77篇 |
2013年 | 107篇 |
2012年 | 79篇 |
2011年 | 101篇 |
2010年 | 80篇 |
2009年 | 81篇 |
2008年 | 77篇 |
2007年 | 50篇 |
2006年 | 38篇 |
2005年 | 26篇 |
2004年 | 13篇 |
2003年 | 22篇 |
2002年 | 19篇 |
2001年 | 12篇 |
2000年 | 14篇 |
1999年 | 5篇 |
1998年 | 15篇 |
1997年 | 13篇 |
1996年 | 11篇 |
1995年 | 15篇 |
1994年 | 10篇 |
1993年 | 6篇 |
1992年 | 5篇 |
1991年 | 11篇 |
1990年 | 3篇 |
1989年 | 7篇 |
1988年 | 7篇 |
1987年 | 5篇 |
1986年 | 1篇 |
1985年 | 2篇 |
1984年 | 5篇 |
1983年 | 2篇 |
1982年 | 6篇 |
1981年 | 3篇 |
1980年 | 2篇 |
1979年 | 2篇 |
1978年 | 4篇 |
1977年 | 1篇 |
1976年 | 2篇 |
1973年 | 1篇 |
排序方式: 共有1649条查询结果,搜索用时 0 毫秒
21.
Nowadays different kinds of double-skin facades are developed and used in new architectural projects. The aim of these facades is, on the one hand, to increase internal comfort and, on the other hand, to decrease energy consumption. In order to optimise the overall performance of the double-skin façades, their detailed behaviour needs to be better understood. The prediction of the airflow within the channel (between the two glazings) is very important for understanding of the double-skin facades behaviour, especially in summer conditions. A comprehensive modelling of a compact double-skin facade equipped with a venetian blind and forced ventilation is proposed here. The modelling is done using the CFD (computational fluid dynamics) approach to assess the air movement within the ventilated facade channel. Three-dimensional airflow is modelled using a homogeneous porous media representation, in order to reduce the size of the mathematical model. A parametric study is proposed here, analysing the impact of three parameters on the airflow development: slat tilt angle, blind position and air outlet position. The distance between the blind and the external glazing was found to have a major impact on the velocity profiles inside the double-skin facade channel. 相似文献
22.
Foisel Hans-Martin Jaeger Monika Westphal F.-Joachim Ovsthus Knut Bischoff Jean-Claude 《Photonic Network Communications》2001,3(1-2):41-48
The commonly used IP-backbone network architecture of today is IP/ATM/SDH/WDM. This architecture has many redundant functionalities and is not optimized to transport IP traffic. New approaches for simplified network architectures try to eliminate redundant functionalities and to decrease the protocol overhead and thereby transport IP as efficiently as possible over WDM-based optical networks. EURESCOM project P918 Integration of IP-over-optical networks: networking and management investigated scenarios for optimized IP transport in WDM-based backbone networks. In this paper, three architectures, namely Gigabit Ethernet, Packet over Sonet/SDH and Dynamic Packet Transport are investigated and evaluated as an alternative to the IP/ATM/SDH/WDM architecture. 相似文献
23.
Wireless Personal Communications - Fog computing is an emerging paradigm that provides confluence facilities between Internet of Things (IoT) devices and cloud. The fog nodes process the... 相似文献
24.
Barbara Kramhöller Monika Pischetsrieder Theodor Severin 《Zeitschrift für Lebensmitteluntersuchung und -Forschung A》1993,197(3):227-229
When dextrins or starch are heated with propyl-amine in neutral aqueous solution at 100–130° C a brown colouration is observed. From the reaction mixture 3-hydroxy-2-methyl-1-propyl-4(1H)-pyridone11, 1,4-dihy-dro-2-methyl-1-propyl-4-propylimino-3-pyridinol12 and 5-hydroxymethyl-1-propyl-pyrrol-2-aldehyde13 can be extracted with organic solvents and separated by HPLC. Enzymatic hydrolysis effects the release of 1(3-hydroxy-1-propyl-2-pyrrolyl)-1-ethanone10 from a glycosidically bound precursor.
Maillard Reaktionen von Dextrinen und Stärke
Zusammenfassung Erhitzt man Dextrine oder Stärke mit Propylamin in neutraler wäßriger Lösung auf 100–130 °C, so beobachtet man eine braune Färbung. Aus der Reaktionsmischung lassen sich 3-Hydroxy-2-methyl-1-propyl-4(1H)-pyridon11, 1,4-Dihydro-2-methyl-1-pro-pyl-4-propylimino-3-pyridinol12 und 5-Hydroxymethyl-1-propyl-pyrrol-2-aldehyd13 mit organischen Lösungsmitteln extrahieren und durch HPLC trennen. Nach enzymatischer Hydrolyse der wasserlöslichen Fraktion ist 1(3-Hydroxy-1-propyl-2-pyrrolyl)-1-ethanon10 isolierbar.相似文献
25.
26.
Geetam Singh Tomar Laxmi Shrivastava Sarita Singh Bhadauria 《Wireless Personal Communications》2014,77(4):2723-2733
In mobile ad hoc networks, congestion occurs due to limited sources of the network, which leads to packet losses, bandwidth degradation and wastes time and energy on congestion recovery. Various techniques have been developed in attempt to minimize congestion in uniformly distributed networks. In this paper, a load balanced congestion adaptive routing algorithm has been proposed for randomly distributed networks. In the proposed algorithm two metrics: traffic load density and life time associated with a routing path, have been used to determine the congestion status and weakest node of the route. The route with low traffic load density and maximum life time is selected for packet transmission. 相似文献
27.
Wireless Personal Communications - Miscellaneous issues related to wireless sensor networks (WSN) like clustering of sensor nodes, load balancing amongst the cluster heads, energy efficient... 相似文献
28.
Wireless Personal Communications - In general, Electrocardiogram (ECG) signal gets corrupted by variety of noise at the time of its acquisition. Unfortunately, these noise tend to mask the crucial... 相似文献
29.
Monika Pinchas 《Signal, Image and Video Processing》2012,6(2):325-340
In this paper, I propose for the noiseless, real and two independent quadrature carrier case some approximated conditions
on the step-size parameter, on the equalizer’s tap length and on the channel power, related to the nature of the chosen equalizer
and input signal statistics, for which a blind equalizer will not converge anymore. These conditions are valid for type of
blind equalizers where the error that is fed into the adaptive mechanism that updates the equalizer’s taps can be expressed
as a polynomial function of the equalized output of order three like in Godard’s algorithm. Since the channel power is measurable
or can be calculated if the channel coefficients are given, there is no need anymore to carry out any simulation with various
step-size parameters and equalizer’s tap length for a given equalization method and input signal statistics in order to find
the maximum step-size parameter for which the equalizer still converges. 相似文献
30.
Effects of manufacturing tolerances in the dimensions and parameters of suspended and inverted microstrip lines on the electrical performance of these lines have been studied through sensitivity analysis. The closed-form expressions recently given by Pramanick and Bhartia for the analysis of these lines have been used to derive the mathematical expressions for various sensitivities and the dependence of sensitivities on the aspect ratios and on the substrate dielectric constant has been depicted graphically. Generally speaking, the effects of tolerances are seen to be reflected much more sharply in the sensitivities of the characteristic impedance than in those of the effective dielectric constant. Many other useful inferences are also drawn from the sensitivity graphs. The conclusions are presented in tabular form, so as to be of direct help to the user. 相似文献