全文获取类型
收费全文 | 388篇 |
免费 | 29篇 |
国内免费 | 13篇 |
专业分类
电工技术 | 6篇 |
综合类 | 24篇 |
化学工业 | 96篇 |
金属工艺 | 9篇 |
机械仪表 | 13篇 |
建筑科学 | 23篇 |
矿业工程 | 1篇 |
能源动力 | 6篇 |
轻工业 | 142篇 |
石油天然气 | 15篇 |
武器工业 | 2篇 |
无线电 | 29篇 |
一般工业技术 | 34篇 |
冶金工业 | 12篇 |
原子能技术 | 4篇 |
自动化技术 | 14篇 |
出版年
2024年 | 1篇 |
2023年 | 2篇 |
2022年 | 2篇 |
2021年 | 4篇 |
2020年 | 10篇 |
2019年 | 10篇 |
2018年 | 8篇 |
2017年 | 12篇 |
2016年 | 21篇 |
2015年 | 14篇 |
2014年 | 14篇 |
2013年 | 30篇 |
2012年 | 38篇 |
2011年 | 39篇 |
2010年 | 21篇 |
2009年 | 37篇 |
2008年 | 13篇 |
2007年 | 17篇 |
2006年 | 16篇 |
2005年 | 22篇 |
2004年 | 12篇 |
2003年 | 22篇 |
2002年 | 9篇 |
2001年 | 8篇 |
2000年 | 6篇 |
1999年 | 6篇 |
1998年 | 9篇 |
1997年 | 3篇 |
1996年 | 3篇 |
1995年 | 3篇 |
1994年 | 6篇 |
1992年 | 1篇 |
1991年 | 2篇 |
1990年 | 1篇 |
1989年 | 1篇 |
1988年 | 1篇 |
1987年 | 2篇 |
1984年 | 2篇 |
1979年 | 1篇 |
1976年 | 1篇 |
排序方式: 共有430条查询结果,搜索用时 15 毫秒
21.
Patrícia Costa Sandra Gonçalves Patrícia Valentão Paula B. Andrade Carlos Almeida José M.F. Nogueira Anabela Romano 《Food chemistry》2013
We investigated the metabolic profile and biological activities of the essential oil and polar extracts of Lavandula pedunculata subsp. lusitanica (Chaytor) Franco collected in south Portugal. Gas chromatography–mass spectrometry (GC–MS) analysis revealed that oxygen-containing monoterpenes was the principal group of compounds identified in the essential oil. Camphor (40.6%) and fenchone (38.0%) were found as the major constituents. High-performance liquid chromatography with diode array detection (HPLC–DAD) analysis allowed the identification of hydroxycinnamic acids (3-O-caffeoylquinic, 4-O-caffeoylquinic, 5-O-caffeoylquinic and rosmarinic acids) and flavones (luteolin and apigenin) in the polar extracts, with rosmarinic acid being the main compound in most of them. The bioactive compounds from L. pedunculata polar extracts were the most efficient free-radical scavengers, Fe2+ chelators and inhibitors of malondialdehyde production, while the essential oil was the most active against acetylcholinesterase. Our results reveal that the subspecies of L. pedunculata studied is a potential source of active metabolites with a positive effect on human health. 相似文献
22.
食品着色剂诱惑红(AlluraRed)是七十年代美国经过严格毒理学研究及安全性评估后推出的一种毒性小、安全性高、色光鲜艳,已在世界各国批准使用并将逐渐取代其他红色谱食用合成色素的食品、药品、化妆品着色剂新品种。在食品、药品、化妆品、饲料、玩具等行业中有越来越大的用途。本文研究了诱惑红在不同pH值介质中的吸光度的变化,其结果有助于着色剂诱惑红在各领域中的更广泛应用。 相似文献
23.
食物中抗性淀粉的研究进展 总被引:15,自引:1,他引:15
在查阅的近十几年对淀粉在人肠道内消化吸收的文献基础上,综述了食物中抗性淀粉的研究进展,抗性淀粉是指不能在健康正常人小肠中消化吸收的淀粉及其降解物食中物存在抗性淀粉可分为3类,物理包埋淀粉(RSI)抗性淀粉颗粒(RS2)和老化淀粉(RS3)其检测一般采用体外肠道模拟酶解法,影响食物中抗性淀粉形成的因素主要有淀粉自身的理化性质,食物中的其它成分,处理方式和工艺以及食物形态等,抗性淀粉属于人体无法消化吸 相似文献
24.
25.
Pryor E Kotarek JA Moss MA Hestekin CN 《International journal of molecular sciences》2011,12(12):9369-9388
Early stages of insulin aggregation, which involve the transient formation of oligomeric aggregates, are an important aspect in the progression of Type II diabetes and in the quality control of pharmaceutical insulin production. This study is the first to utilize capillary electrophoresis (CE) with ultraviolet (UV) detection to monitor insulin oligomer formation at pH 8.0 and physiological ionic strength. The lag time to formation of the first detected species in the aggregation process was evaluated by UV-CE and thioflavin T (ThT) binding for salt concentrations from 100 mM to 250 mM. UV-CE had a significantly shorter (5-8 h) lag time than ThT binding (15-19 h). In addition, the lag time to detection of the first aggregated species via UV-CE was unaffected by salt concentration, while a trend toward an increased lag time with increased salt concentration was observed with ThT binding. This result indicates that solution ionic strength impacts early stages of aggregation and β-sheet aggregate formation differently. To observe whether CE may be applied for the analysis of biological samples containing low insulin concentrations, the limit of detection using UV and laser induced fluorescence (LIF) detection modes was determined. The limit of detection using LIF-CE, 48.4 pM, was lower than the physiological insulin concentration, verifying the utility of this technique for monitoring biological samples. LIF-CE was subsequently used to analyze the time course for fluorescein isothiocyanate (FITC)-labeled insulin oligomer formation. This study is the first to report that the FITC label prevented incorporation of insulin into oligomers, cautioning against the use of this fluorescent label as a tag for following early stages of insulin aggregation. 相似文献
26.
采用紫外可见分光光度法研究了CaCl2溶液在是否施加交变磁场及不同温度、浓度下吸光度的变化情况,证明了磁处理对水分子间结构状态的影响.通过对CaCO3溶液的电导率与加磁反应时间之间的实验分析,进一步验证了磁处理对CaCO3晶核生成的促进作用. 相似文献
27.
28.
The degree of organic pollution in natural waters of northern Greece has been evaluated through measurement of TOC, DO, fluorescence, absorbance and complexing capacity. Additionally certain other parameters were measured like temperature, conductance, hardness, alkalinity and total iron content to get a better idea of the extent of pollution. The results showed that Lake Agios Vasilios was the most heavily polluted. On the other hand the River Loudias has greater organic charge than the River Axios. 相似文献
29.
Naziha Ainseba‐Chirani Zahra Dembahri Caroline Tokarski Christian Rolando Mustapha Benmouna 《Polymer International》2011,60(7):1024-1029
Newly designed gels for electrophoresis protein separation were synthesized from acrylamide, N,N′‐methylenebis (acrylamide) and dextran mixtures. Radical polymerization was initiated by ammonium persulfate and N,N,N′,N′‐tetramethylethylenediamine. The time dependence of absorbance during polymerization was monitored using UV‐visible spectroscopy. The exothermic polymerization process exhibited a sharp rise of temperature reminiscent of the Trommsdorff effect. The swelling kinetics of the synthesized gels was examined in deionized water and buffer solutions. One of the challenges was to find an alternative to commercial products, sold as mixtures with no detailed chemical contents, commonly used in sodium dodecylsulfate polyacrylamide gel electrophoresis (SDS‐PAGE) for protein separation. For this reason, a systematic comparison was made of the properties of one of the most commonly used commercial gels, Duracryl? from Genomics Solution Inc., and those of the synthesized polyacrylamide/dextran gels. Copyright © 2011 Society of Chemical Industry 相似文献
30.
Reconsidering the quantitative analysis of organic carbon concentrations in size exclusion chromatography 总被引:1,自引:0,他引:1
The evaluation of the molecular size distribution of natural organic matter (NOM) in aquatic environments via size exclusion chromatography (SEC) is important for the understanding of environmental processes such as nutrient cycling and pollutant transport as well as of technical water treatment processes. The use of organic carbon (OC) detectors has become popular in recent studies due to improved availability and quantification possibilities, which supposedly are superior to those of ultraviolet (UV) detectors. A set of 12 NOM samples was used to demonstrate the limitations of online OC detection (OCD) when analyzing complex aquatic organic matter. A novel evaluation approach for SEC data is introduced by combining the information from UV absorbance (UVA) and OCD chromatograms as well as offline total OC (t-OC) and dissolved OC-specific UVA (SUVA) measurements. It could be shown that about 70% of certain OC components were not detected with the OCD system used in this study. For the investigated samples, these types of carbon accounted for up to 72% of the t-OC, i.e. for such NOM samples quantification by OCD is not possible or at least highly questionable. The addition of an oxidant improved the overall oxidation efficiency only slightly. Most likely NOM that predominantly consists of polysaccharides and features a nominal molecular weight of 150 kg/mol or more was responsible for low OCD yields. For future applications, a further improvement of the OCD system would be worthwhile so that quantitative analytical data on the molecular size distribution of NOM and its structural characteristics such as the SUVA distribution can be obtained. 相似文献