全文获取类型
收费全文 | 1598篇 |
免费 | 137篇 |
国内免费 | 35篇 |
专业分类
电工技术 | 10篇 |
综合类 | 149篇 |
化学工业 | 919篇 |
金属工艺 | 7篇 |
机械仪表 | 8篇 |
建筑科学 | 298篇 |
矿业工程 | 14篇 |
能源动力 | 47篇 |
轻工业 | 122篇 |
水利工程 | 31篇 |
石油天然气 | 30篇 |
无线电 | 4篇 |
一般工业技术 | 93篇 |
冶金工业 | 15篇 |
原子能技术 | 3篇 |
自动化技术 | 20篇 |
出版年
2024年 | 2篇 |
2023年 | 8篇 |
2022年 | 25篇 |
2021年 | 26篇 |
2020年 | 28篇 |
2019年 | 27篇 |
2018年 | 27篇 |
2017年 | 35篇 |
2016年 | 48篇 |
2015年 | 31篇 |
2014年 | 67篇 |
2013年 | 101篇 |
2012年 | 107篇 |
2011年 | 113篇 |
2010年 | 123篇 |
2009年 | 119篇 |
2008年 | 104篇 |
2007年 | 132篇 |
2006年 | 130篇 |
2005年 | 118篇 |
2004年 | 75篇 |
2003年 | 69篇 |
2002年 | 43篇 |
2001年 | 31篇 |
2000年 | 23篇 |
1999年 | 30篇 |
1998年 | 21篇 |
1997年 | 23篇 |
1996年 | 14篇 |
1995年 | 18篇 |
1994年 | 13篇 |
1993年 | 11篇 |
1992年 | 5篇 |
1991年 | 11篇 |
1990年 | 3篇 |
1989年 | 3篇 |
1987年 | 2篇 |
1986年 | 2篇 |
1984年 | 1篇 |
1951年 | 1篇 |
排序方式: 共有1770条查询结果,搜索用时 15 毫秒
51.
52.
Analysis of gas holdup and bubble behavior in a biopolymer solution inside a bioreactor using tomography and dynamic gas disengagement techniques
下载免费PDF全文
![点击此处可从《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
53.
54.
55.
Rajib Nayak James Gomes 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2010,85(1):59-76
BACKGROUND: A generalized methodology for the synthesis of a hybrid controller for affine systems using sequential adaptive networks (SAN) is presented. SAN consists of an assembly of neural networks that are ordered in a chronological sequence, with one network assigned to each sampling interval. Using a suitable process model based on oxygen metabolism and an a priori objective function, a hybrid control law is derived that can use online measurements and the states predicted by SAN for computing the desired control action. RESULTS: The performance of the SAN–hybrid controller is tested for simulated fed‐batch production of methionine for three different process conditions. Simulations assume that online measurements of dissolved oxygen (DO) concentration are available. The performance of the SAN–hybrid controller gave an NRMSE of ~10?4 in the absence of noise, ~10?3 and ~10?2 for ± 5% and ± 10% noise in the DO measurement and ~10?2 for parameter uncertainty when compared with the ideal model prediction. CONCLUSIONS: The observed performance for unmeasured state prediction and control implementation shows that the proposed SAN–hybrid controller can efficiently compute the manipulated variable required to maintain methionine production along the optimized trajectory for different conditions. The test results show that the SAN–hybrid controller can be used for online real‐time implementation in fed‐batch bioprocesses. Copyright © 2009 Society of Chemical Industry 相似文献
56.
P. D. Nemade S. M. Dutta H. S. Shankar 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2010,85(1):77-84
BACKGROUND: The constructed soil filter (CSF), also known as soil biotechnology is a system for water renovation, which makes use of formulated media, culture of soil micro‐ and macro‐organisms, additives and plantation to purify water and wastewater. The process gives benefits in terms of applicability across very small to large scale, natural aeration, absence of moving parts, no biological sludge generation, odor free green aesthetic ambience. RESULTS: Residence time distribution (RTD) studies were carried out using laboratory scale CSF. Pulse potassium bromide tracer tests were carried out to determine RTD, and the Peclet number found to be 9–13 for a 2 m bed, and 2–3 for a 0.30 m bed with oxygen transfer of 0.08 h?1. CONCLUSION: The two‐channel dispersion model for flow behavior shows a good fit to the experimental data, indicating a reactor Peclet number 9–13 for a 2 m bed and 2–3 for a 0.3m bed. Oxygen transfer studies carried out using various methods gave an oxygen transfer coefficient of about 0.08 h?1. Wastewater purification studies indicate overall COD removal rate of around 50 mg L?1 h?1, suggesting that highly aerobic conditions are prevalent in the CSF system. Copyright © 2009 Society of Chemical Industry 相似文献
57.
58.
Zakir M. Hirani Zia Bukhari Joan Oppenheimer Patrick Jjemba Mark W. LeChevallier Joseph G. Jacangelo 《Water research》2013
Membrane bioreactors (MBRs) are often a preferred treatment technology for satellite water recycling facilities since they produce consistent effluent water quality with a small footprint and require little or no supervision. While the water quality produced from centralized MBRs has been widely reported, there is no study in the literature addressing the effluent quality from a broad range of satellite facilities. Thus, a study was conducted to characterize effluent water qualities produced by satellite MBRs with respect to organic, inorganic, physical and microbial parameters. Results from sampling 38 satellite MBR facilities across the U.S. demonstrated that 90% of these facilities produced nitrified (NH4-N <0.4 mg/L-N) effluents that have low organic carbon (TOC <8.1 mg/L), turbidities of <0.7 NTU, total coliform bacterial concentrations <100 CFU/100 mL and indigenous MS-2 bacteriophage concentrations <21 PFU/100 mL. Multiple sampling events from selected satellite facilities demonstrated process capability to consistently produce effluent with low concentrations of ammonia, TOC and turbidity. UV-254 transmittance values varied substantially during multiple sampling events indicating a need for attention in designing downstream UV disinfection systems. Although enteroviruses, rotaviruses and hepatitis A viruses (HAV) were absent in all samples, adenoviruses were detected in effluents of all nine MBR facilities sampled. The presence of Giardia cysts in filtrate samples of two of nine MBR facilities sampled demonstrated the need for an appropriate disinfection process at these facilities. 相似文献
59.
60.
Membranes are located in a membrane module that physically seals and isolates the feed stream from the permeate flux in membrane bioreactors (MBRs). Therefore, module type, structure, and geometrical configuration are critical design considerations affecting membrane performance in MBRs. In this study, impact of membrane module design on treatment and filtration performance of MBRs was investigated. For this purpose, two flat sheet membrane modules with different outlet structures and module geometries, including rectangular- and D-shaped, were tested. In addition to the differences in outlet structure and module geometry, size of circular structures which supported membranes in rectangular- and D-shaped modules differed from each other. Considering the results, permeate quality was not affected from the change in the module design. However, the most remarkable impact of the module design was observed on the transmembrane pressure (TMP) evolution and fouling potential. D-shaped membrane module including smaller circular structures resulted in a decrease in fouling potential and thus, this module could be operated longer time in comparison to rectangular-shaped membrane module without a severe TMP increase. The observed differences in TMP increase and fouling potential lead to the hypothesis that module design is a critical factor affecting filtration performance in MBRs. 相似文献