全文获取类型
收费全文 | 504篇 |
免费 | 34篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 3篇 |
化学工业 | 184篇 |
金属工艺 | 7篇 |
机械仪表 | 6篇 |
建筑科学 | 37篇 |
矿业工程 | 1篇 |
能源动力 | 7篇 |
轻工业 | 67篇 |
水利工程 | 9篇 |
石油天然气 | 2篇 |
无线电 | 13篇 |
一般工业技术 | 82篇 |
冶金工业 | 83篇 |
自动化技术 | 38篇 |
出版年
2024年 | 1篇 |
2023年 | 9篇 |
2022年 | 38篇 |
2021年 | 41篇 |
2020年 | 19篇 |
2019年 | 20篇 |
2018年 | 11篇 |
2017年 | 19篇 |
2016年 | 29篇 |
2015年 | 10篇 |
2014年 | 23篇 |
2013年 | 41篇 |
2012年 | 31篇 |
2011年 | 41篇 |
2010年 | 27篇 |
2009年 | 25篇 |
2008年 | 26篇 |
2007年 | 22篇 |
2006年 | 21篇 |
2005年 | 18篇 |
2004年 | 8篇 |
2003年 | 7篇 |
2002年 | 7篇 |
2001年 | 5篇 |
2000年 | 5篇 |
1999年 | 11篇 |
1998年 | 3篇 |
1997年 | 1篇 |
1996年 | 2篇 |
1995年 | 1篇 |
1994年 | 2篇 |
1993年 | 1篇 |
1991年 | 1篇 |
1990年 | 2篇 |
1988年 | 1篇 |
1986年 | 1篇 |
1985年 | 1篇 |
1983年 | 1篇 |
1982年 | 1篇 |
1981年 | 1篇 |
1980年 | 1篇 |
1979年 | 2篇 |
1974年 | 1篇 |
1940年 | 1篇 |
排序方式: 共有539条查询结果,搜索用时 15 毫秒
41.
42.
Evaluation of the Feasibility of Irrigation Storage in a Flood Detention Pond in an Agricultural Catchment in Northern Italy 总被引:3,自引:2,他引:1
During recent years, the international attention paid to rational use and saving of water has increased, partly because of
frequent water shortages occurring also in countries not usually involved in these problems, and partly as a consequence of
rising conflicts on water allocation. Hence it is important to find new surface-water volumes satisfying agricultural water
demand, as well as new ways and areas to store them. The simulation model presented by the paper enables evaluation, in a
phase of design feasibility analysis, of whether a flood detention pond can be adapted to act as water storage during irrigation
periods in order to reduce agricultural water shortages; it simulates detention pond response to floods and droughts under
different hydraulic conditions and reservoir management rules. The first policy goal of the model is to maintain the stored
volume within the maximum admissible for flood safety. The second goal is to maintain at the same time a minimum flow in the
river and to satisfy irrigation water demand. The model, implemented in a purpose-made simulation software, was applied to
an Italian river in the Emilia Romagna region: the results demonstrate that the use of a flood detention pond as an irrigation
reservoir is not only possible, if it complies with the operating rules that emerge from this study, but also it brings tangible
benefits in reducing agricultural water deficit. 相似文献
43.
S. K. Varma Erica Corral Erika Esquivel Daniel Salas 《Metallurgical and Materials Transactions A》1999,30(9):2539-2545
A solutionizing heat treatment of 2014 aluminum alloy reinforced with 0.15 volume fraction of alumina particles (VFAP) results
in deformation-induced precipitation during rolling and tensile deformation, with 0.10 VFAP, at room temperature. The extent
of precipitation increases with increase in time and/or temperature of solutionizing. An attempt has been made to identify
the various types of precipitates in the samples deformed to a given strain and in fractured conditions. The work-hardening
curves and tensile properties of the composites have been shown to be dependent on the time and temperature combination of
the solutionizing process. 相似文献
44.
45.
Erica Bazzan Mariaenrica Tin Alvise Casara Davide Biondini Umberto Semenzato Elisabetta Cocconcelli Elisabetta Balestro Marco Damin Claudia Maria Radu Graziella Turato Simonetta Baraldo Paolo Simioni Paolo Spagnolo Marina Saetta Manuel G. Cosio 《International journal of molecular sciences》2021,22(12)
Extracellular vesicles (EVs) are a family of particles/vesicles present in blood and body fluids, composed of phospholipid bilayers that carry a variety of molecules that can mediate cell communication, modulating crucial cell processes such as homeostasis, induction/dampening of inflammation, and promotion of repair. Their existence, initially suspected in 1946 and confirmed in 1967, spurred a sharp increase in the number of scientific publications. Paradoxically, the increasing interest for EV content and function progressively reduced the relevance for a precise nomenclature in classifying EVs, therefore leading to a confusing scientific production. The aim of this review was to analyze the evolution of the progress in the knowledge and definition of EVs over the years, with an overview of the methodologies used for the identification of the vesicles, their cell of origin, and the detection of their cargo. The MISEV 2018 guidelines for the proper recognition nomenclature and ways to study EVs are summarized. The review finishes with a “more questions than answers” chapter, in which some of the problems we still face to fully understand the EV function and potential as a diagnostic and therapeutic tool are analyzed. 相似文献
46.
47.
Behrend Douglas A.; Scofield Jason; Kleinknecht Erica E. 《Canadian Metallurgical Quarterly》2001,37(5):698
L. Markson and P. Bloom (1997) concluded that there was evidence against a dedicated system for word learning on the basis of their finding that children remembered a novel word and a novel fact equally well. However, a word-learning system involves more than recognition memory; it must also provide a means to guide the extension of words to additional exemplars, and words and facts may differ with regard to extendibility. Two studies are reported in which 2–4-year-old children learned novel words and novel facts for unfamiliar objects and then were asked to extend the words and facts to additional exemplars of the training objects. In both studies, children extended the novel word to significantly more category members than they extended the novel fact. The results show that by 2 years of age, children honor the necessary extendibility of novel count nouns but are uncertain about the extendibility of arbitrary facts. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
48.
Patrick L Jacobs Erica R Goldstein Will Blackburn Ihsan Orem John J Hughes 《Journal of the International Society of Sports Nutrition》2009,6(1):9-11
Background
Recent research has indicated that short term administration of glycine propionyl-L-carnitine (GPLC) significantly elevates levels of nitric oxide metabolites at rest and in response to reactive hyperaemia. However, no scientific evidence exists that suggests such supplementation enhances exercise performance in healthy, trained individuals. The purpose of this study was to examine the effects of GPLC on the performance of repeated high intensity stationary cycle sprints with limited recovery periods in resistance trained male subjects. 相似文献49.
Curt L. Elderkin Lynda D. Corkum Claudia Bustos Erica L. Cunningham David J. Berg 《Journal of Great Lakes research》2012
Burrowing mayfly species of the genus Hexagenia are well known indicators of environmental health in lakes and rivers. Two species, H. limbata and H. rigida, are indistinguishable as nymphs and as adult females. Our objectives were to develop a genetic technique to distinguish between the two species and identify morphological features that separate cryptic nymphs and adult females. Fifty nymphs were collected before emergence from 10 sites throughout the western basin of Lake Erie in 2004 and 2005. Using known specimens of adult aerial male H. limbata and H. rigida, we used the mitochondrial cytochrome c oxidase subunit 1 (COI) gene to identify a 16 base pair (bp) difference between species. DNA sequencing confirmed correct species identification based on differences in abdominal pigmentation patterns on adult female imagos in 19 of 20 cases; the lone exception was a female with very faint pigmentation. Pigmentation patterns between species were consistent on nymphs, subimagos and imagos of both sexes. Populations of both species are panmictic across the western basin of Lake Erie, but H. limbata is the numerically dominant species, representing 70 to 100% of nymphs at sites in both years. A separate lineage of H limbata was discovered in the samples. The ability to distinguish nymphs of the two species will aid in developing more sensitive ecosystem indicators. 相似文献
50.
Abdelwahhab KHATIR Roberto CAPOZUCCA Samir KHATIR Erica MAGAGNINI 《Frontiers of Structural and Civil Engineering》2022,16(8):976
Vibration-based damage detection methods have become widely used because of their advantages over traditional methods. This paper presents a new approach to identify the crack depth in steel beam structures based on vibration analysis using the Finite Element Method (FEM) and Artificial Neural Network (ANN) combined with Butterfly Optimization Algorithm (BOA). ANN is quite successful in such identification issues, but it has some limitations, such as reduction of error after system training is complete, which means the output does not provide optimal results. This paper improves ANN training after introducing BOA as a hybrid model (BOA-ANN). Natural frequencies are used as input parameters and crack depth as output. The data are collected from improved FEM using simulation tools (ABAQUS) based on different crack depths and locations as the first stage. Next, data are collected from experimental analysis of cracked beams based on different crack depths and locations to test the reliability of the presented technique. The proposed approach, compared to other methods, can predict crack depth with improved accuracy. 相似文献