全文获取类型
收费全文 | 861篇 |
免费 | 21篇 |
专业分类
电工技术 | 7篇 |
综合类 | 4篇 |
化学工业 | 184篇 |
金属工艺 | 15篇 |
机械仪表 | 13篇 |
建筑科学 | 53篇 |
能源动力 | 25篇 |
轻工业 | 87篇 |
水利工程 | 1篇 |
无线电 | 71篇 |
一般工业技术 | 139篇 |
冶金工业 | 209篇 |
原子能技术 | 19篇 |
自动化技术 | 55篇 |
出版年
2022年 | 7篇 |
2021年 | 22篇 |
2020年 | 9篇 |
2019年 | 11篇 |
2018年 | 12篇 |
2017年 | 12篇 |
2016年 | 10篇 |
2015年 | 12篇 |
2014年 | 14篇 |
2013年 | 44篇 |
2012年 | 25篇 |
2011年 | 41篇 |
2010年 | 25篇 |
2009年 | 23篇 |
2008年 | 24篇 |
2007年 | 39篇 |
2006年 | 20篇 |
2005年 | 20篇 |
2004年 | 23篇 |
2003年 | 19篇 |
2002年 | 19篇 |
2001年 | 13篇 |
2000年 | 20篇 |
1999年 | 24篇 |
1998年 | 62篇 |
1997年 | 43篇 |
1996年 | 22篇 |
1995年 | 18篇 |
1994年 | 15篇 |
1993年 | 24篇 |
1992年 | 11篇 |
1991年 | 13篇 |
1990年 | 10篇 |
1989年 | 17篇 |
1988年 | 9篇 |
1987年 | 8篇 |
1986年 | 12篇 |
1985年 | 7篇 |
1984年 | 9篇 |
1983年 | 8篇 |
1982年 | 8篇 |
1981年 | 8篇 |
1978年 | 6篇 |
1976年 | 14篇 |
1975年 | 6篇 |
1974年 | 6篇 |
1973年 | 5篇 |
1972年 | 10篇 |
1971年 | 6篇 |
1966年 | 5篇 |
排序方式: 共有882条查询结果,搜索用时 15 毫秒
141.
Strategy for Conversion of Chlorine Chemistry . After years of discussion about ?cessation of chlorine chemistry”?, the study entitled ?Conversion of Chlorine Chemistry”? [1] commissioned by the Environmental Ministry of the State of Hesse in Germany and undertaken by Prognos AG provides the very first detailed comparative ecological and economical assessment of production process and products of ?chlorine chemistry”? and industrially feasible alternatives and presents a strategy for partial transformation. This accomplished on the basis of a systematic assessment of risks and benefits, as demanded by the Geman parliametary commission ?Protection of Humankind and the Environment”?. 相似文献
142.
Sara E. Shinn Andrew Proctor Jamie I. Baum 《Journal of the American Oil Chemists' Society》2018,95(1):5-11
The new American Dietary Guidelines now recommend optimizing the types of fat consumed instead of reducing or eliminating fat from the diet. Chicken eggs are a means to deliver essential and beneficial human dietary fatty acids (FA), and can be staple component of healthy eating behavior. Additionally, polyunsaturated fatty acids can be increased in the avian egg yolk by simply incorporating selected lipid sources into the avian diet. Poultry feed rich in omega‐3 FA (omega‐3) has allowed commercialization of enriched eggs containing up to 600 mg of omega‐3. Conjugated linoleic acid (CLA) has also been used in the research setting to enrich eggs to provide a portion of the 3–4 g CLA day?1 needed to promote weight loss to combat obesity. However, Americans consume only 50% of the omega‐3 recommended adequate intake, and average CLA consumption is under 600 mg day?1. While a variety of foods are naturally rich in omega‐3, conventional sources of CLA are limited to bovine milk and meat, which do not provide enough CLA to produce clinical effects in a balanced diet. Since eggs and egg‐based products are common in the Western diet, eggs enriched with both omega‐3 and CLA using dietary additions to poultry feed may promote consumption of the recommended levels of these FA. This article reviews the design of poultry eggs with enhanced lipid profiles through dietary intervention, and discusses the future direction of enriched egg research. 相似文献
143.
The introduction of routine patient dosimetry to Brazilian radiological institutions is very necessary in order to meet national and international standard requirements for radiation protection. This work presents a survey of the air kerma-area product (P(KA)), the entrance surface air kerma (K(e)) and the effective dose (E) in common radiographic examinations during the routine of a large public hospital in the city of Belo Horizonte, Brazil. Results draw attention to the use of field sizes larger than the cassette dimension, the lack of both the collimation X-ray beam and the standardisation of the exposure parameters by radiology technicians. 相似文献
144.
145.
Nanoporous anodic aluminium oxide has traditionally been made in one of two ways: mild anodization or hard anodization. The first method produces self-ordered pore structures, but it is slow and only works for a narrow range of processing conditions; the second method, which is widely used in the aluminium industry, is faster, but it produces films with disordered pore structures. Here we report a novel approach termed "pulse anodization" that combines the advantages of the mild and hard anodization processes. By designing the pulse sequences it is possible to control both the composition and pore structure of the anodic aluminium oxide films while maintaining high throughput. We use pulse anodization to delaminate a single as-prepared anodic film into a stack of well-defined nanoporous alumina membrane sheets, and also to fabricate novel three-dimensional nanostructures. 相似文献
146.
Crossing of the Elbe‐Seitenkanal and the Mittellandkanal using HDD‐Technology for a 380 km long pipeline. The federal network of waterways and canals today comprises approximately 7500 km of inland waterways. Not restricted to economic use in transportation, the waterways also have a function in the water supply and distribution (water for industry and agriculture, flood protection etc.). As owner of federal waterways, the Federal Republic of Germany, according to the Basic law, section 87 and 89, manages these by an independent administrative authority, the Wasser‐ und Schifffahrtsverwaltung des Bundes (WSV), localy represented by the appropriate office, the Wasser‐ und Schifffahrtsamt (WSA). The WSA acts according to § 31 WaStrG as authorizing agency for river‐ and navigation‐specific police approval of third‐party installations intended for crossing or culverting the Federal Waterway route, as in this case. In the course of constructing a 380 km long pipeline from Stade to Teutschenthal (PST) a total of 203 horizontal directional drillings (HDD) were carried out. 24 of them concerned the crossing of big rivers and channels. Two technically extremely demanding projects proved to be the crossing of the Elbe‐Seitenkanal (ESK) and the crossing of the Mittellandkanal (MLK). 相似文献
147.
Klaus Dieter Schwenke Constanze Knopfe Arndt Seifert Eckhard Grnitz Dietrich Zirwer 《Journal of the science of food and agriculture》2001,81(1):126-134
The effect of progressive acetylation upon the conformation of the 11S globulin legumin from faba bean has been studied using chemical analysis, UV, fluorescence and CD spectroscopy, viscometry and analytical ultracentrifugation. The modification did not induce complete dissociation of the oligomeric protein. Only 30% of the protein was found to be a dissociated 3S subunit after excessive acetylation, whereas 70% was a dimeric legumin aggregate with a molecular mass of about 700 kDa. The aggregation of the highly modified legumin in high‐ionic‐strength buffer solution leads to soluble higher legumin oligomers. The acetylation resulted in a moderate molecular expansion of legumin due to a changed tertiary structure, whereas the far‐UV circular dichroism spectra did not provide definitive evidence of a decrease in domain‐stabilizing β‐sheet conformations in their secondary structure. © 2000 Society of Chemical Industry 相似文献
148.
149.
Birgit Breitschuh‐Apostolakis Eckhard Flter 《European Journal of Lipid Science and Technology》2002,104(11):713-719
In this work, the occurrence of solid phase immiscibility during the fractionation process of milk fat is documented. It is shown that solid phase immiscibility occurs in normal fractionation procedures, upon crystallisation at low temperatures and in particular on further fractionation of narrow melting fractions. This phenomenon results in distinct phases of crystallisation. In some cases, the initial phase yields intermediate solid levels independent of increasing supersaturation. The subsequent increase of solids content is solely a contribution of a second, independent crystallisation event. Furthermore, it could be shown that the induction time for the second crystallisation event is not influenced by the presence or absence of the first triacylglyceride group. These results clearly indicate the independence of the crystallisation of the different immiscible fractions in terms of kinetics and thermodynamics. The different processes during the crystallisation process are monitored simply by viscosimetry. 相似文献
150.
本研究的目的在于开发利用超声喷嘴浸渍纺织材料的新方法,使纺织品具有既定的功能性,并为进一步应用纳米技术以获得功能化产业用纺织品,以及服装用和装饰用纺织品打下技术基础。 相似文献