全文获取类型
收费全文 | 1177篇 |
免费 | 34篇 |
专业分类
电工技术 | 44篇 |
综合类 | 3篇 |
化学工业 | 172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 | 90篇 |
水利工程 | 16篇 |
石油天然气 | 4篇 |
无线电 | 98篇 |
一般工业技术 | 180篇 |
冶金工业 | 167篇 |
原子能技术 | 10篇 |
自动化技术 | 202篇 |
出版年
2024年 | 2篇 |
2023年 | 6篇 |
2022年 | 2篇 |
2021年 | 12篇 |
2020年 | 8篇 |
2019年 | 22篇 |
2018年 | 21篇 |
2017年 | 24篇 |
2016年 | 27篇 |
2015年 | 23篇 |
2014年 | 25篇 |
2013年 | 71篇 |
2012年 | 57篇 |
2011年 | 76篇 |
2010年 | 68篇 |
2009年 | 62篇 |
2008年 | 114篇 |
2007年 | 89篇 |
2006年 | 70篇 |
2005年 | 83篇 |
2004年 | 52篇 |
2003年 | 37篇 |
2002年 | 43篇 |
2001年 | 25篇 |
2000年 | 9篇 |
1999年 | 18篇 |
1998年 | 15篇 |
1997年 | 18篇 |
1996年 | 11篇 |
1995年 | 17篇 |
1994年 | 13篇 |
1993年 | 6篇 |
1992年 | 12篇 |
1991年 | 2篇 |
1990年 | 6篇 |
1989年 | 5篇 |
1988年 | 15篇 |
1987年 | 4篇 |
1986年 | 6篇 |
1985年 | 5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 | 2篇 |
1975年 | 3篇 |
1972年 | 1篇 |
1947年 | 1篇 |
排序方式: 共有1211条查询结果,搜索用时 765 毫秒
91.
92.
This paper presents a comprehensive overview of comparative performance characteristics of proton exchange membrane (PEM) and solid oxide steam (SOS) electrolysers based on a thermodynamic analysis. The main factors which influence electrolyser energy and exergy efficiencies were temperature, summation of overpotentials, applied voltage, and to a lesser extent pressure. It is found that anodic overpotentials make up a majority of the total overpotentials in both electrolyser types studied and therefore further development of catalysts to reduce the overpotentials was recommended. 相似文献
93.
James Tickner Raffaele Bencardino Greg Roach 《Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms》2010,268(2):99-3128
Activation yields have been measured for (γ,n) reactions of the elements Ru, Rh, Pd, Ir and Pt. Metallic foils of natural isotopic composition were irradiated using Bremsstrahlung radiation produced from an electron linear accelerator operated with electron beam energies in the range 11-14 MeV. Activation products, including both unstable ground states and metastates were measured using a high-purity germanium detector. Cross-sections were estimated from the yield data by assuming a simple two-parameter model for the shape of the cross-section with energy. 相似文献
94.
Jeff D. Gamlin Jordan F. Clark Greg Woodside Roy Herndon 《Canadian Metallurgical Quarterly》2001,127(2):171-174
Sulfur hexafluoride (SF6) was injected into a 9 km reach of the Santa Ana River in Orange County, CA, over a period of two weeks. The entire flow of this river, which averaged 2.8 m3 s?1, percolated into the ground in the field area. The tracer was monitored at wells near the river to determine subsurface flow patterns and flow times with an accuracy much greater than could be achieved using numerical simulations of ground-water flow. During the experiment, SF6 effectively tagged 3.7 × 106 m3 of water. The tracer plume was mapped in the subsurface for 18 months and indicates that linear ground-water velocities averaged about 2 km year?1. The tracer reached two wells adjacent to the river (about 200 m away) within three weeks, giving evidence that SF6 was not retarded significantly relative to the ground-water flow. This is in agreement with previous laboratory experiments. 相似文献
95.
Conducted 2 experiments to examine the word recognition processes of 2nd, 4th, and 6th graders. In Exp I, 72 Ss named target words that were primed by words that had more than 1 meaning. Targets were related either to the more or less frequent sense of the ambiguous prime or were unrelated to it. Findings indicate that older Ss were more likely than younger Ss to restrict processing of ambiguous words to the most frequent meaning. While younger Ss showed approximately equal facilitation for words related to either meaning, regardless of each one's relative frequency, 6th graders apparently retrieved only the most frequent meaning. Exp II, with 36 Ss, was similar to Exp I but included neutral primes and varied the interval between presentation of prime and target. Results show that all groups showed automatic retrieval of both meanings of the ambiguous word. For 6th graders, however, this retrieval was followed by a 2nd stage, in which attention was allocated to the more frequent meaning, maintaining it, while the less frequent meaning was inhibited. Overall data indicate that older children use meaning frequency to narrow the amount of information kept active following word recognition. (34 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
96.
We identified categories of counselor self-talk and explored for possible dimensions that underlie the categories. The 38 counselors conducted 25-min interviews with a female client and then completed a stimulated-recall, thought-listing exercise. Trained judges categorized the resulting 768 self-talk statements into 14 categories, with approximately 61% of the statements accounted for by the four largest categories (client-focused questions, summarizations, inferences or hypotheses, and self-instructions). A multidimensional scaling analysis identified two underlying dimensions that reflect Attending and Assessing vs Information Seeking and Integrative Understanding vs Intervention Planning. The findings are discussed in terms of counselor cognitive processing and are related to previous research on counselor intentions. Suggestions for future research are provided. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
97.
Greg Bronevetsky John Gyllenhaal Bronis R. de Supinski 《International journal of parallel programming》2009,37(3):250-265
Despite its ease of use, OpenMP has failed to gain widespread use on large scale systems, largely due to its failure to deliver
sufficient performance. Our experience indicates that the cost of initiating OpenMP regions is simply too high for the desired
OpenMP usage scenario of many applications. In this paper, we introduce CLOMP, a new benchmark to characterize this aspect
of OpenMP implementations accurately. CLOMP complements the existing EPCC benchmark suite to provide simple, easy to understand
measurements of OpenMP overheads in the context of application usage scenarios. Our results for several OpenMP implementations
demonstrate that CLOMP identifies the amount of work required to compensate for the overheads observed with EPCC. We also
show that CLOMP also captures limitations for OpenMP parallelization on SMT and NUMA systems. Finally, CLOMPI, our MPI extension
of CLOMP, demonstrates which aspects of OpenMP interact poorly with MPI when MPI helper threads cannot run on the NIC. 相似文献
98.
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
99.
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
100.
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