全文获取类型
收费全文 | 3850篇 |
免费 | 107篇 |
国内免费 | 65篇 |
专业分类
电工技术 | 430篇 |
综合类 | 131篇 |
化学工业 | 1401篇 |
金属工艺 | 132篇 |
机械仪表 | 46篇 |
建筑科学 | 124篇 |
矿业工程 | 42篇 |
能源动力 | 176篇 |
轻工业 | 543篇 |
水利工程 | 11篇 |
石油天然气 | 147篇 |
武器工业 | 5篇 |
无线电 | 121篇 |
一般工业技术 | 461篇 |
冶金工业 | 26篇 |
原子能技术 | 28篇 |
自动化技术 | 198篇 |
出版年
2024年 | 6篇 |
2023年 | 45篇 |
2022年 | 69篇 |
2021年 | 88篇 |
2020年 | 66篇 |
2019年 | 64篇 |
2018年 | 60篇 |
2017年 | 91篇 |
2016年 | 86篇 |
2015年 | 86篇 |
2014年 | 152篇 |
2013年 | 179篇 |
2012年 | 222篇 |
2011年 | 284篇 |
2010年 | 231篇 |
2009年 | 256篇 |
2008年 | 246篇 |
2007年 | 232篇 |
2006年 | 269篇 |
2005年 | 188篇 |
2004年 | 184篇 |
2003年 | 159篇 |
2002年 | 146篇 |
2001年 | 107篇 |
2000年 | 107篇 |
1999年 | 97篇 |
1998年 | 74篇 |
1997年 | 54篇 |
1996年 | 35篇 |
1995年 | 29篇 |
1994年 | 33篇 |
1993年 | 17篇 |
1992年 | 20篇 |
1991年 | 18篇 |
1990年 | 8篇 |
1989年 | 4篇 |
1988年 | 2篇 |
1987年 | 3篇 |
1986年 | 1篇 |
1985年 | 1篇 |
1979年 | 1篇 |
1976年 | 1篇 |
1974年 | 1篇 |
排序方式: 共有4022条查询结果,搜索用时 15 毫秒
12.
13.
14.
This study demonstrates that state observers can be developed and applied to infer the composition profiles of reactive distillation columns from noise-contaminated temperature measurements. The design and implementation of a Kalman filter (KF) and a Luenberger observer (LO) are carried out, and their performances are quantitatively assessed. The reliability, accuracy, and robustness of the two designs method are examined and compared quantitatively. The design and implementation of a Luenberger observer are simpler and easier to carry out than those of a Kalman filter. On the other hand, a Kalman filter is found to be more robust to a noisy measurements, erroneous initial estimates, and model uncertainties. A Luenberger observer could be used for composition estimation of reactive distillation when an ideal model of the system can reasonably approximate the real system; otherwise, a Kalman filter is recommended to be applied in more practical situations. 相似文献
15.
Yi‐Hung Chen Ching‐Yuan Chang Wei‐Ling Su Chun‐Yu Chiu Yue‐Hwa Yu Pen‐Chi Chiang Chiung‐Fen Chang Je‐Lueng Shie Chyow‐San Chiou Sally IM Chiang 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2005,80(1):68-75
This study investigates the ozonation of CI Reactive Black 5 (RB5) by using the rotating packed bed (RPB) and completely stirred tank reactor (CSTR) as ozone contactors. The RPB, which provides high gravitational force by adjusting the rotational speed, was employed as a novel ozone contactor. The same ozone dosage was separately introduced into either the RPB or the CSTR for the investigation, while the experimental solution was continuously circulated within the apparatus consisting of the RPB and CSTR. The decolorization and mineralization efficiencies of RB5 in the course of ozonation are compared for these two methods. Moreover, the dissolved and off‐gas ozone concentrations were simultaneously monitored for the further analysis. As a result, the ozone mass transfer rate per unit volume of the RPB was significantly higher because of its higher mass transfer coefficient and gas–liquid concentration driving force. Furthermore, ozonation kinetics was found to be independent of the gravitational magnitude of an ozone gas–liquid contactor. Therefore, the results suggest employing RPBs as ozone‐contacting devices with the advantage of volume reduction. The experimental results, which can be used for further modeling of the ozonation process in the RPB, also show the requirement of correct design for the RPB. Consequently, the present study is useful for the understanding of practical application of RPBs. Copyright © 2004 Society of Chemical Industry 相似文献
16.
Motofumi Suzuki Kohei Kinoshita Shinji Jomori Hidehiko Harada Kaoru Nakajima Kenji Kimura 《Thin solid films》2007,515(22):8281-8284
The initial stage of iron silicide formation is investigated by high-resolution Rutherford backscattering spectroscopy. During the Fe deposition on Si(001) at 470 °C, the formation of FeSi2 is confirmed by the surface peak analysis. Initially, FeSi2 grows epitaxially so that one of the major crystallographic axes is parallel to the <111> axis of the Si substrate. With increasing Fe deposition, the deviation between the major crystallographic axis of the silicide region and Si<111> increases although the electron diffraction pattern is independent of the amount of Fe deposition. Therefore, the subsurface crystallographic structure of iron silicide is transformed from a cubic-like to a low-symmetry structure. 相似文献
17.
18.
1μm宽硅深槽刻蚀技术 总被引:1,自引:1,他引:0
介绍了硅深槽刻蚀的基本原理和影响刻蚀效果的几个主要工艺因素。提出了一种实现1μm宽的硅深槽刻蚀工艺途径;并给出了1μm宽、8μm深、侧壁及底部光洁的硅深槽刻蚀工艺条件。 相似文献
19.
This paper deals with an advanced static Var compensator (ASVC) using quad-series voltage-source PAM inverters. The ASVC consists of four three-phase voltage-source inverters with a common dc capacitor and four three-phase transformers, each primary winding of which is connected in series with each other. Each inverter outputs a square-wave voltage, while the synthesized output voltage of the ASVC has a 24-step wave shape. This results not only in a great reduction of harmonic currents and dc voltage ripples but also in fewer switching and snubbing losses. In this paper, transient analysis is performed with the focus on the response of reactive power and the resonance between the dc capacitor and ac reactors. Experimental results obtained from a small-rated laboratory model of 10 kVA are also shown to verify analytical results based on the p-q transformation. The analytical results help in the design of system parameters such as the capacity of the dc capacitor and feedback gains. 相似文献
20.
A model has been developed to study the effects of chemical kinetics on the residue curve maps (RCM) for reactive distillation systems with liquid phase splitting. In the model, chemical reaction can occur in both or only one of the two liquid phases. The heating policy V/V0=H/H0 is applied so that the kinetic effect can be described by a single parameter, the Damköhler number Da. The effects of reaction kinetics on pseudohomogeneous and heterogeneous mixtures have been compared. The properties of their RCMs are the same outside, but are fully different inside the liquid-liquid (L-L) region if they have different chemical equilibrium curves. Inside the L-L region, the chemical equilibrium curve coincides to a unique reactive liquid-liquid tie line in case that the pseudohomogeneous chemical equilibrium curve intersects with the L-L envelope. When the reaction occurs in only one of the two liquid phases, the residue curves inside the L-L region are strongly affected by the L-L envelope, especially at high Da. In the present paper, first an illustrative arbitrary reaction system, and then the reaction of cyclohexene with water to cyclohexanol are analysed with respect to their RCMs. 相似文献