全文获取类型
收费全文 | 2364篇 |
免费 | 125篇 |
国内免费 | 6篇 |
专业分类
电工技术 | 31篇 |
综合类 | 9篇 |
化学工业 | 688篇 |
金属工艺 | 36篇 |
机械仪表 | 78篇 |
建筑科学 | 114篇 |
矿业工程 | 2篇 |
能源动力 | 94篇 |
轻工业 | 291篇 |
水利工程 | 9篇 |
石油天然气 | 5篇 |
武器工业 | 1篇 |
无线电 | 219篇 |
一般工业技术 | 426篇 |
冶金工业 | 91篇 |
原子能技术 | 19篇 |
自动化技术 | 382篇 |
出版年
2024年 | 3篇 |
2023年 | 23篇 |
2022年 | 106篇 |
2021年 | 177篇 |
2020年 | 62篇 |
2019年 | 66篇 |
2018年 | 86篇 |
2017年 | 75篇 |
2016年 | 77篇 |
2015年 | 72篇 |
2014年 | 116篇 |
2013年 | 174篇 |
2012年 | 112篇 |
2011年 | 184篇 |
2010年 | 135篇 |
2009年 | 118篇 |
2008年 | 122篇 |
2007年 | 112篇 |
2006年 | 90篇 |
2005年 | 69篇 |
2004年 | 64篇 |
2003年 | 58篇 |
2002年 | 54篇 |
2001年 | 33篇 |
2000年 | 25篇 |
1999年 | 28篇 |
1998年 | 32篇 |
1997年 | 30篇 |
1996年 | 27篇 |
1995年 | 18篇 |
1994年 | 16篇 |
1993年 | 13篇 |
1992年 | 6篇 |
1991年 | 5篇 |
1990年 | 5篇 |
1989年 | 9篇 |
1988年 | 6篇 |
1987年 | 3篇 |
1985年 | 5篇 |
1984年 | 16篇 |
1983年 | 7篇 |
1982年 | 7篇 |
1981年 | 6篇 |
1980年 | 3篇 |
1979年 | 7篇 |
1977年 | 5篇 |
1976年 | 5篇 |
1974年 | 4篇 |
1967年 | 3篇 |
1966年 | 3篇 |
排序方式: 共有2495条查询结果,搜索用时 31 毫秒
991.
Franco Chialva Peter A. P. Liddle Giovanni Doglia 《Zeitschrift für Lebensmitteluntersuchung und -Forschung A》1983,176(5):363-366
Summary A series of essential oils obtained from samples ofArtemisia absinthium L. from various geographical origins and collected at different heights were analysed by means of glass-capillary gas chromatography. The main components were identified by means of GC, GC-MS, IR,1HNMR and13CNMR.Several chemotypes were detected: in the western Alpine arc (Italy) the most important chemotype, above 1,000 m., was acis-epoxy-ocimene type, while at lower levels a-thujone type predominated.Plants originating from France could be divided into a chrysanthenyl acetate and a saßinyl acetate chemotype; plants from Siberia, Rumania and some from Valle d'Aosta belonged to a mixed type.
Chemotaxonomie von Wermut (Artemisia absinthum L.)I. Zusammensetzung des ätherischen Öls einiger Chemotypen
Zusammenfassung Die ätherischen Öle des Wermuts, aus mehreren Herkunften und aus verschiedenen Höhen, wurden durch Capillargaschromatographie bestimmt und durch MS, IR,1HNMR,13CNMR identifiziert.Dabei konnten verschiedene Chemotypen festgestellt werden. In den Westalpen ist der cis-Epoxycimen Typ über 1000 m der wichtigste Typ, während der-Thujon-Typ in niedrigeren Zonen vorherrscht.Französische Muster gehörten zu den Chrysanthenylacetat-und Sabinylacetat-Chemotypen, Muster aus Sibirien, Rumänien und dem Aostatal dagegen zu einem gemischten Typ.相似文献
992.
993.
Giovanni Celano Philippe Castagliola 《Quality and Reliability Engineering International》2016,32(2):681-696
Very recently, monitoring the ratio of two normal random variables by means of control charts has been investigated in statistical process control literature. The industrial implementation of these control charts involves monitoring of processes where the correct proportion of two ingredients or elements within a product should be maintained under statistical control, monitoring of quality characteristics measuring the performance of a product as the ratio before and after some specific operation, for example, a chemical reaction following the introduction of an additive in a product, and monitoring of a chemical or physical property of a product, which is itself defined and computed as a ratio. This paper presents a Phase II synthetic control chart with each subgroup consisting of n > 1 sample units. Several tables are generated and commented to show the statistical performance of the investigated chart for known and random shift sizes affecting the in‐control ratio. A performance comparison with another control chart already proposed in literature shows the advantages associated to the implementation of the synthetic control chart. An illustrative example from the food industry is given for illustration. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
994.
Fabio Isa Marco Salvalaglio Yadira Arroyo Rojas Dasilva Mojmír Meduňa Michael Barget Arik Jung Thomas Kreiliger Giovanni Isella Rolf Erni Fabio Pezzoli Emiliano Bonera Philippe Niedermann Pierangelo Gröning Francesco Montalenti Hans von Känel 《Advanced materials (Deerfield Beach, Fla.)》2016,28(5):884-888
995.
Although many successful techniques have been proposed in the last decades for extracting the small signal equivalent circuit for microwave transistors from scattering parameter measurements, small signal modeling is still object of intense research. Further improvement and development of the proposed methods are incessantly required to take into account the continuous and rapid evolution of the transistor technology. The purpose of this article is to facilitate the choice of the most appropriate strategy for each particular case. For that, we present a brief but thorough comparative study of analytical techniques developed for modeling different types of advanced microwave transistors: GaAs HEMTs, GaN HEMTs, and FinFETs. It will be shown that a crucial step for a successful modeling is to adapt accurately the small signal equivalent circuit topology under “cold” condition to each investigated technology. © 2008 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2008. 相似文献
996.
Marco Roccetti Vittorio Ghini Giovanni Pau Paola Salomoni Maria Elena Bonfigli 《Multimedia Tools and Applications》2001,14(1):23-53
We describe the design and the experimental evaluation of a playout delay control mechanism we have developed in order to support unicast, voice-based audio communications over the Internet. The proposed mechanism was designed to dynamically adjust the talkspurt playout delays to the traffic conditions of the underlying network without assuming either the existence of an external mechanism for maintaining an accurate clock synchronization between the sender and the receiver during the audio communication, or a specific distribution of the audio packet transmission delays. Performance figures derived from several experiments are reported that illustrate the adequacy of the proposed mechanism in dynamically adjusting the audio packet playout delay to the network traffic conditions while maintaining a small percentage of packet loss. 相似文献
997.
Renaud P Pourcelot L Métivier JM Morello M 《The Science of the total environment》2003,309(1-3):257-264
We observed the relationship between present-day 137Cs surface activity and the rainfall in May 1986 to establish a relevant map of 137Cs deposition over eastern France. This study was performed in an area of the lower Rh?ne valley where clayey soils are assumed to trap caesium efficiently. Based on the rainwater/airborne activity ratio deduced from this relationship, we verified that present-day activities, measured in clayey soils of this type, are relatively representative of the initial depositions. The interlocked contaminated areas of the resulting map can be related to rainfall occurrences, as is the case for all countries affected by the Chernobyl fallout. This map can be reasonably compared with those obtained for countries bordering France in terms of both activity levels and extent of homogeneous activity areas. Lastly, we demonstrate that it would not be possible to produce a coherent map of initial fallout by extending the campaign over the whole of the eastern territory based on present-day soil activity measurements alone. Hence, only the relationship between 137Cs deposition and the rainfall of the first week of May 1986 can be used to construct a map depicting the Chernobyl fallout over eastern France. 相似文献
998.
Maurizio Addamo Vincenzo Augugliaro Marianna Bellardita Agatino Di Paola Vittorio Loddo Giovanni Palmisano Leonardo Palmisano Sedat Yurdakal 《Catalysis Letters》2008,121(1-2):58-62
X-ray photoelectron spectroscopy (XPS) has been applied to the study pertaining to preparation and characterization of catalysts
used in propylene polymerization. The analysis has indicated support/donor interaction in active support (adduct) and active
support/TiCl4 interaction during catalyst preparation process. A systematic study has been made to identify suitable adduct from a set
of three adducts for catalyst synthesis. Precise binding energy of Titanium species on catalyst surface has been measured
and its dispersion on support has been evaluated to correlate catalyst performance with the surface spectroscopic parameters. 相似文献
999.
1000.
Costa Alberto; Peppe Antonella; Caltagirone Carlo; Carlesimo Giovanni Augusto 《Canadian Metallurgical Quarterly》2008,22(3):283
This study investigated prospective memory and its relationship to executive and memory functions in persons with Parkinson's disease (PD). Twenty-three individuals with PD and 25 healthy comparison participants participated in the study. In the prospective memory tasks, participants were asked to execute 3 actions after 20 min (time-based condition) or after a timer ring (event-based condition). A score was computed for the correct recall of the intention to perform the actions (prospective component) and for the correct execution of the actions (retrospective component). Participants with PD also received an extensive neuropsychological test battery. PD participants were less accurate than comparison participants in the prospective component of the time-based but not the event-based task. Individuals with PD were also impaired on the retrospective component of both tasks. In the PD group, a general trend toward significant correlations was found between performance level on the prospective memory component of the time-based task and scores on executive and working memory measures. These results document that prospective memory is impaired in PD possibly in relation to a dysregulation of cognitive functions associated with frontal systems. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献