全文获取类型
收费全文 | 1272篇 |
免费 | 39篇 |
专业分类
电工技术 | 44篇 |
综合类 | 3篇 |
化学工业 | 184篇 |
金属工艺 | 57篇 |
机械仪表 | 21篇 |
建筑科学 | 75篇 |
矿业工程 | 9篇 |
能源动力 | 63篇 |
轻工业 | 130篇 |
水利工程 | 16篇 |
石油天然气 | 4篇 |
无线电 | 101篇 |
一般工业技术 | 191篇 |
冶金工业 | 197篇 |
原子能技术 | 10篇 |
自动化技术 | 206篇 |
出版年
2024年 | 2篇 |
2023年 | 6篇 |
2022年 | 4篇 |
2021年 | 12篇 |
2020年 | 8篇 |
2019年 | 22篇 |
2018年 | 23篇 |
2017年 | 27篇 |
2016年 | 27篇 |
2015年 | 24篇 |
2014年 | 25篇 |
2013年 | 72篇 |
2012年 | 60篇 |
2011年 | 76篇 |
2010年 | 68篇 |
2009年 | 68篇 |
2008年 | 118篇 |
2007年 | 95篇 |
2006年 | 74篇 |
2005年 | 87篇 |
2004年 | 53篇 |
2003年 | 40篇 |
2002年 | 49篇 |
2001年 | 31篇 |
2000年 | 11篇 |
1999年 | 24篇 |
1998年 | 22篇 |
1997年 | 27篇 |
1996年 | 20篇 |
1995年 | 17篇 |
1994年 | 14篇 |
1993年 | 10篇 |
1992年 | 14篇 |
1991年 | 4篇 |
1990年 | 8篇 |
1989年 | 5篇 |
1988年 | 15篇 |
1987年 | 5篇 |
1986年 | 6篇 |
1985年 | 6篇 |
1984年 | 9篇 |
1983年 | 5篇 |
1982年 | 2篇 |
1981年 | 2篇 |
1980年 | 2篇 |
1979年 | 3篇 |
1976年 | 3篇 |
1975年 | 3篇 |
1947年 | 1篇 |
1923年 | 1篇 |
排序方式: 共有1311条查询结果,搜索用时 15 毫秒
101.
Kazuhiro Ohyama Teruo Hamaoka Greg Asher Mark Sumner 《Electrical Engineering in Japan》2009,166(1):67-81
This paper proposes a method for the design of the adaptive rotor flux observer gain to improve stability at low speed and in regenerating mode. The method is based on stability analysis, which utilizes a linearized model considering all systems, including each control loop. Therefore, the proposed method considers the effects of motor constants and control circuit constants. The stability analysis using the transfer function for the rotor speed considers the arrangement of poles and zeros and the steady‐state error. The rotor flux observer gain which improves the stability for each operating condition is ascertained. This paper also proposes a real‐time tuning method for the observer gain. The validity of the proposed method was confirmed by simulation using Matlab Simulink and by experiment. © 2008 Wiley Periodicals, Inc. Electr Eng Jpn, 166(1): 67–81, 2009; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20715 相似文献
102.
Chapman Christopher L.; Baker Elizabeth L.; Porter Greg; Thayer Stephen D.; Burlingame Gary M. 《Canadian Metallurgical Quarterly》2010,14(1):15
The present study seeks to establish the validity of the Group Psychotherapy Intervention Rating Scale (GPIRS), an observer-rated measure of the quality of group leader interventions. Concurrent validity was tested by comparing GPIRS results to 2 group gold standard process measures, the Hill Interaction Matrix and the Group Climate Questionnaire. Significant correlations between leader intervention scores and group member perceptions of group climate, as well as verbal interaction scores, were found. In addition, results indicated correlations between interventions aimed to gain balance between confrontation and warmth and member-rated levels of cohesion. Results lend support for the concurrent validity of the GPIRS. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
103.
This study evaluated the production of biodiesel using fish oil as raw material. Two-stage alkaline-catalysis transesterification
was performed with 6/1 molar ratio of methanol to oil at 55°C in the presence of 1 wt. % base amount of potassium hydroxide
(KOH). The fuel properties of the biodiesel were further analyzed. The characterizations of the produced biodiesel showed
that it met ASTM D 6751 standard with respect to acid number, flash point, water and sediment, free and total glycerin, sulfur
content, distillation temperature, etc. It was found that cold soak and oxidative stability were out spec due to the high
amount of polyunsaturated fatty acid present in the fish oil. However, through blending with used cooking oil biodiesel, in
spec biodiesel fuel could be achieved. 相似文献
105.
Márcia Campos Brasil Annelise Engel Gerbase Maria Augusta de Luca José Ribeiro Gregório 《Journal of the American Oil Chemists' Society》2007,84(3):289-295
Hybrid organic–inorganic films were prepared using four different hydroxylated soybean oils (HSO) or epoxidized soybean oil
as organic precursor and tetraethyl orthosilicate (TEOS) as inorganic precursor in a mass ratio of HSO:TEOS of 90:10. The
films were macroscopically homogeneous and were characterized by swelling and extraction in solvent, thermogravimetric analysis
(TGA), scanning electron microscopy (SEM) including energy dispersive spectroscopy (EDX), adhesion and hardness. Their properties
varied as a function of the number of OH groups present in the HSO. The best hybrid system was HSOF198/TEOS, with an OH value
of 198 mg of KOH/g, which presents lower swelling coefficient, very good adhesion on aluminium surface and good hardness. 相似文献
106.
107.
108.
Jairam Vanamala Greg CobbJulio Loaiza Kilsun YooLeonard M. Pike Bhimanagouda S. Patil 《Food chemistry》2007,105(4):1404-1411
Bioactive compounds in citrus fruits have been shown to be protective against chronic diseases such as cancer and heart disease, but their levels may be affected by postharvest treatments such as storage and irradiation. In this study, grapefruits were exposed to gamma irradiation at 0, 150 and 300 Gy and then stored at 10 °C for 36 d, followed by an additional 20 d at 20 °C. Flavonoid content, terpenoid content, quality (acidity and total soluble solids) and phenylalanine ammonia-lyase (PAL) activity were evaluated at regular intervals during storage. Irradiation and storage affected (P ? 0.05) the levels of bioactive compounds in grapefruit; however, the effect of storage was prominent. Irradiation differentially affected the flavonoid content of pulp and peel. Fruits exposed to 300 Gy had higher (P ? 0.01) narirutin content in peel compared to control fruits at 12 and 56 d after storage. While storage increased the d-limonene and myrcene content in all treatments, control fruit had higher terpenoid content at the end of the storage. PAL activity was found to be in traces in the peel. In general, irradiation or storage had no considerable effect on total soluble solids; however, acidity decreased (P ? 0.05) with storage. 相似文献
109.
Connectionist models are introduced as promising tools for understanding the nature of psychological disorders and guiding their assessment. Specifically, ways in which connectionist models can guide the following aspects of the assessment process are described: understanding what constructs are relevant to assess, designing approaches to assessing these constructs, and understanding individual differences in data from assessments. Two extended examples are given based on the authors' research on cognitive aspects of depression and Alzheimer's disease. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
110.
Research shows consistent relations between personality and job performance. In this study the authors develop and test a model of job performance that examines the mediating effects of cognitive-motivational work orientations on the relationships between personality traits and performance in a sales job (N=164). Covariance structural analyses revealed proximal motivational variables to be influential mechanisms through which distal personality traits affect job performance. Specifically, striving for status and accomplishment mediate the effects of Extraversion and Conscientiousness on ratings of sales performance. Although Agreeableness was related to striving for communion, neither Agreeableness nor communion striving was related to success in this sales job. The importance of the proposed motivational orientations model is discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献