全文获取类型
收费全文 | 3829篇 |
免费 | 140篇 |
国内免费 | 4篇 |
专业分类
电工技术 | 77篇 |
综合类 | 6篇 |
化学工业 | 975篇 |
金属工艺 | 65篇 |
机械仪表 | 59篇 |
建筑科学 | 285篇 |
矿业工程 | 17篇 |
能源动力 | 81篇 |
轻工业 | 606篇 |
水利工程 | 23篇 |
石油天然气 | 11篇 |
无线电 | 251篇 |
一般工业技术 | 516篇 |
冶金工业 | 460篇 |
原子能技术 | 27篇 |
自动化技术 | 514篇 |
出版年
2022年 | 40篇 |
2021年 | 48篇 |
2020年 | 38篇 |
2019年 | 51篇 |
2018年 | 52篇 |
2017年 | 38篇 |
2016年 | 86篇 |
2015年 | 74篇 |
2014年 | 133篇 |
2013年 | 181篇 |
2012年 | 169篇 |
2011年 | 149篇 |
2010年 | 144篇 |
2009年 | 163篇 |
2008年 | 167篇 |
2007年 | 150篇 |
2006年 | 165篇 |
2005年 | 128篇 |
2004年 | 115篇 |
2003年 | 102篇 |
2002年 | 60篇 |
2001年 | 52篇 |
2000年 | 64篇 |
1999年 | 49篇 |
1998年 | 64篇 |
1997年 | 50篇 |
1996年 | 36篇 |
1995年 | 33篇 |
1994年 | 47篇 |
1993年 | 41篇 |
1992年 | 36篇 |
1991年 | 38篇 |
1990年 | 42篇 |
1989年 | 43篇 |
1988年 | 36篇 |
1987年 | 49篇 |
1986年 | 31篇 |
1985年 | 53篇 |
1984年 | 54篇 |
1983年 | 39篇 |
1982年 | 33篇 |
1981年 | 43篇 |
1980年 | 50篇 |
1979年 | 39篇 |
1978年 | 39篇 |
1977年 | 49篇 |
1976年 | 47篇 |
1975年 | 33篇 |
1974年 | 39篇 |
1973年 | 31篇 |
排序方式: 共有3973条查询结果,搜索用时 15 毫秒
71.
A turbulent environment characterized by unsteady economic cycles, customized products, a growing bandwidth of products, an exploding number of variants and shorter product life cycles force manufacturers to permanent adaptation of their factories. Flexible and changeable structures will be required to enable factories dealing with the technological challenges and economic pressure of the future competitively. In order to achieve changeability objectives in manufacturing, a detailed analysis of existing structures and its representative attributes is essential. It is the basis for systematic structure planning of factories. In this paper a method for analyzing the capacitive and technological structure of a factory embedded in a network of manufacturing and its network of suppliers is presented. The synchronization of product and production development under the influence of change is intended. Therefore, the structural views of product and production are specifically in focus of the method. Based on the results of the analysis models an approach of a tool for giving product and production structure dynamism is suggested to investigate the effects and dependencies of change drivers in manufacturing. 相似文献
72.
73.
In this article we present our recent efforts in designing a comprehensive consistent scientific workflow, nicknamed Wolf2 Pack, for force-field optimization in the field of computational chemistry. Atomistic force fields represent a multiscale bridge that connects high-resolution quantum mechanics knowledge to coarser molecular mechanics-based models. Force-field optimization has so far been a time-consuming and error-prone process, and is a topic where the use of a scientific workflow can provide obvious great benefits. As a case study we generate a gas-phase force field for methanol using Wolf2 Pack, with special attention given toward deriving partial atomic charges. 相似文献
74.
75.
76.
Assessing the quality of use case descriptions 总被引:1,自引:0,他引:1
77.
78.
Werner Henning und Karl Herrmann 《Zeitschrift für Lebensmitteluntersuchung und -Forschung A》1980,171(2):111-118
Zusammenfassung Blätter wie Früchte von 6 SortenPrunus domestica-Pflaumen enthalten hauptsächlich 3-Rutinoside, in geringerer Konzentration 3-Glucoside und 3-Galaktoside von Kämpferol und Quercetin Bowie Quercetin-3-rhamnosid. Dagegen weisen Pflaumen vonPrunus salicina (2 untersuchte Sorten) Kämpferol-3,7-bisrhamnosid und Kämpferol-3-arabinosyl-7-rhamnosid als Hauptflavonole auf. Hierdurch ist eine Unterscheidung beider Arten leicht and sicher mög-lich. Weiterhin konnten inSalicina-Pflaumen Kämpfe-rol-3-rutinosid sowie Quercetin-3-rhamnosid, -xylosid,-glucosid, -galaktosid, --l-arabinofuranosid and -rutinosid, auch Quercetin-7-rhamnosid and Kämpferol-7-glucosid nachgewiesen werden.Die Gesamtgehalte an Flavonolglykosiden lagen bei den untersuchten Pflaumensorten vonPrunus domestica (P. salicina) bei 2500–3340 (7170, 10350) ppm in Blättern and 20–52 (8, 24) in Früchten, jeweils bezogen auf Frischgewicht.
11. Mitt.: Henning W, Herrmann K (1980) Z Lebensm Unters Forsch 170:433–444
Auszug aus der Promotionsarbeit von W. Henning: Bestimmung der in Pflaumen, Kirschen, Pfirsichen and Aprikosen vorkommenden Flavonolglykoside unter Anwendung der Hochdruckflüssigkeitschromatographie. Diss. Univ. Hannover 1980 相似文献
Flavonol glycosides of plums of the species Prunus domestica L. and Prunus salicina lindley12. Phenolics of fruits
Summary Leaves and fruits from 6 cultivars ofPrunus domestica plums contain mainly 3-rutinosides; in smaller concentrations the 3-glycosides and 3-galactosides of kaempferol and quercetin as well as quercetin-3-rhamnoside are present. On the other hand, in plums ofPrunus salicina (2 examined cultivars) main flavonols are kaempferol-3,7-bisrhamnoside and kaempferol-3arabinosyl-7-rhamnoside. Due to the difference in composition, differentiation of these species will be easy and reliable. Additionally kaempferol-3-rutinoside and quercetin-3-rhamnoside, -xyloside,-glucoside, -galactoside, --l-arabinofuranoside and-rutinoside, and also quercetin-7-rhamnoside and kaempferol-7-glucoside could be detected inP. salicina plums. The total content of flavonol glycosides in the investigated plums ofPrunus domestica (P. salicina) were based on fresh weight about 2500–3340 (7170, 10350) ppm in the leaves and 20–52 (8, 24) ppm in the fruits.
11. Mitt.: Henning W, Herrmann K (1980) Z Lebensm Unters Forsch 170:433–444
Auszug aus der Promotionsarbeit von W. Henning: Bestimmung der in Pflaumen, Kirschen, Pfirsichen and Aprikosen vorkommenden Flavonolglykoside unter Anwendung der Hochdruckflüssigkeitschromatographie. Diss. Univ. Hannover 1980 相似文献
79.
Malte H.G. Wichmann Jan Sumfleth Marino Quaresimin Karl Schulte 《Engineering Fracture Mechanics》2006,73(16):2346-2359
Nanoparticles and especially carbon nanotubes (CNTs) provide a high potential for the modification of polymers. They are very effective fillers regarding mechanical properties, especially toughness. Furthermore, they allow the implication of functional properties, which are connected to their electrical conductivity, into polymeric matrices. In the present paper, different nanoparticles, as fumed silica and carbon black, were used to optimise the epoxy matrix system of a glass-fibre-reinforced composite. Their nanometre-size enables their application as particle-reinforcement in FRPs produced by the resin-transfer-moulding method (RTM), without being filtered by the glass-fibre bundles. Additionally, an electrical field was applied during curing, in order to enhance orientation of the nanofillers in z-direction. The interlaminar shear strengths of the nanoparticle modified composites were significantly improved (+16%) by adding only 0.3 wt.% of CNTs. The interlaminar toughness GIc and GIIc was not affected in a comparable manner. The laminates containing carbon nanotubes exhibited a relatively high electrical conductivity at very low filler contents, which allows the implication of functional properties, such as stress-strain monitoring and damage detection. 相似文献
80.
Grammer Karl; Fink Bernhard; M?ller Anders P.; Manning John T. 《Canadian Metallurgical Quarterly》2005,131(5):658
Evolutionary behavioral biology suggests that certain characteristics of the human face and body are important for mate preferences and are therefore subject to sexual selection. J. Weeden and J. Sabini (see record 2005-11504-001) identify a number of weaknesses in the association between traits' attractiveness and health. In contrast, the authors argue that (a) studies on preferences for physical characteristics that rely on 1 trait permit only limited interpretation, (b) limitations placed on J. Weeden and J. Sabini's review exclude important associations, (c) there are misconceptions in their treatment of some traits, and (d) their selected literature provides an inaccurate picture regarding effect size. The authors suggest that future research in this field should seek conceptual and methodological constancy in trait selection and in the evaluation of attractiveness- and health-related traits. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献