全文获取类型
收费全文 | 201篇 |
免费 | 19篇 |
国内免费 | 1篇 |
专业分类
化学工业 | 72篇 |
金属工艺 | 2篇 |
机械仪表 | 11篇 |
建筑科学 | 6篇 |
能源动力 | 5篇 |
轻工业 | 52篇 |
水利工程 | 1篇 |
一般工业技术 | 39篇 |
冶金工业 | 8篇 |
自动化技术 | 25篇 |
出版年
2023年 | 2篇 |
2022年 | 2篇 |
2021年 | 16篇 |
2020年 | 5篇 |
2019年 | 9篇 |
2018年 | 7篇 |
2017年 | 7篇 |
2016年 | 8篇 |
2015年 | 6篇 |
2014年 | 16篇 |
2013年 | 19篇 |
2012年 | 19篇 |
2011年 | 16篇 |
2010年 | 10篇 |
2009年 | 9篇 |
2008年 | 13篇 |
2007年 | 10篇 |
2006年 | 2篇 |
2005年 | 3篇 |
2004年 | 6篇 |
2003年 | 1篇 |
2002年 | 5篇 |
2001年 | 3篇 |
2000年 | 3篇 |
1999年 | 1篇 |
1998年 | 4篇 |
1997年 | 4篇 |
1996年 | 6篇 |
1994年 | 1篇 |
1993年 | 1篇 |
1992年 | 3篇 |
1991年 | 1篇 |
1988年 | 1篇 |
1986年 | 1篇 |
1976年 | 1篇 |
排序方式: 共有221条查询结果,搜索用时 38 毫秒
81.
82.
Longitudinal development of chlorophyll and phytoplankton assemblages in a regulated large river (the Ebro River) 总被引:2,自引:0,他引:2
Sabater S Artigas J Durán C Pardos M Romaní AM Tornés E Ylla I 《The Science of the total environment》2008,404(1):196-206
The distribution of chlorophyll and phytoplankton communities were compared to nutrient concentrations and hydrological parameters along the main stretch of the river Ebro. A progressive increase in planktonic chlorophyll was observed from the upper reaches to the middle section of the river. Chlorophyll reached a maximum (60-80 microg L(-1)) in the meandering section (downstream of the city of Zaragoza), where nutrient inputs (both N and P) and the residence time of the water are very high. In this meandering section phytoplankton assemblages consisted of large centric diatoms and Scenedesmus sp.pl. These longitudinal patterns were interrupted by the presence of three large reservoirs in the lower section of the river. In the section below the reservoirs, the shorter residence water time, the presence of the invasive zebra mussel, and the massive macrophyte development may explain the historical decrease in chlorophyll-a (from 20-45 microg L(-1) in the 1990s to the present 2-5 microg L(-1)). Phytoplankton densities were extremely poor in this section of the river, where large colonial Coelastrum sp.pl. and Pediastrum sp.pl. were the most characteristic taxa. 相似文献
83.
Martínez-Verdú F Perales E Chorro E de Fez D Viqueira V Gilabert E 《Journal of the Optical Society of America. A, Optics, image science, and vision》2007,24(6):1501-1515
We present a systematic algorithm capable of searching for optimal colors for any lightness L* (between 0 and 100), any illuminant (D65, F2, F7, F11, etc.), and any light source reported by CIE. Color solids are graphed in some color spaces (CIELAB, SVF, DIN99d, and CIECAM02) by horizontal (constant lightness) and transversal (constant hue angle) sections. Color solids plotted in DIN99d and CIECAM02 color spaces look more spherical or homogeneous than the ones plotted in CIELAB and SVF color spaces. Depending on the spectrum of the light source or illuminant, the shape of its color solid and its content (variety of distinguishable colors, with or without color correspondence) change drastically, particularly with sources whose spectrum is discontinuous and/or very peaked, with correlated color temperature lower than 5500 K. This could be used to propose an absolute colorimetric quality index for light sources comparing the volumes of their gamuts, in a uniform color space. 相似文献
84.
Southern Ocean swimming crab Ovalipes trimaculatus and the Patagonian stone crab Platyxanthus patagonicus are fishing resources with commercial value. Thermal treatment of crabs is necessary to denature muscle proteins, facilitating meat detachment from the crab shell (picking procedure). The proximal composition, protein patterns of crab muscle, thermophysical properties and heat transfer coefficients were determined. Heat transfer during thermal processing of body (i.e., cephalothorax) and claws of both crab species was simulated using a finite element computational code; the simulations were experimentally validated. Color changes in crab muscle during the heating process were measured. Thermal denaturation kinetics of myofibrillar proteins was determined using Differential Scanning Calorimetry (DSC) in small samples previously heated in water under controlled conditions. DSC thermograms of raw crab muscle showed two peaks at 49.0 ± 0.4 and 77.5 ± 0.6 °C corresponding to myosin and actin respectively. Activation energies for the denaturation of myosin (145.70 kJ/mol) and actin (156.42 kJ/mol) were calculated from Arrhenius equation. The degree of denaturation achieved by the myofibrillar proteins at the coldest point of the muscle in body and claws during the heating process was established by considering the protein denaturation kinetics determined by DSC, the activation energies and the heat penetration curves. Adequate conditions for the detachment of meat from the crab exoskeleton were established. The obtained results may help in determining the optimal heating times during the industrialization of these crustaceans. 相似文献
85.
Alba Milln Luis lvarez deCienfuegos Ana Martín‐Lasanta Araceli G. Campaa Juan M. Cuerva 《Advanced Synthesis \u0026amp; Catalysis》2011,353(1):73-78
An efficient protocol for the synthesis of homopropargylic alcohols using propargylic carbonates as pronucleophiles is reported. The reaction is based on a combination of transition metal (palladium) and radical chemistry (titanium). The reaction takes place with an excellent regioselectivity and tolerates a great degree of substitution of the starting propargylic carbonate, thus being an interesting tool in the context of synthetic organic chemistry. 相似文献
86.
Araceli Pérez Silva Ziya Gunata Jean-Paul Lepoutre Eric Odoux 《Food research international (Ottawa, Ont.)》2011,44(9):2930-2937
Green vanilla beans were subjected to the traditional curing process in Mexico. Odor-active potential from beans including 23 compounds was monitored through the analysis of both free and glucosidically bound volatiles. 8 of them were aliphatic aldehydes, acids, alcohol and ketone. 15 molecules were shikimate derivatives in which 13 were detected in glucosylated form. Some glucosides were efficiently hydrolyzed while some others partly or not at all after 90 days of curing. Moreover kinetics of hydrolysis of glucosides were not the same. A major part of glucovanillin was hydrolyzed at the first stages of curing while some other glucosides at the advanced stages. Data support hypothesis that hydrolysis of glucosides during curing is rather enzymatic origin than chemical one. Free shikimate derivatives or those liberated from glucosides are prone to chemical or enzymatic interconversions leading to a significant change in the aroma profile of cured vanilla. 相似文献
87.
Proximate and fatty acid composition in raw and cooked muscle tissue of farmed rainbow trout (Oncorhynchus mykiss) fed with commercial fishmeal 下载免费PDF全文
88.
Immunological Changes Induced in Peach Allergy Patients with Systemic Reactions by Pru p 3 Sublingual Immunotherapy 下载免费PDF全文
89.
A novel synthesis of arylboronic esters by a reductive electrochemical coupling reaction between aromatic halides and pinacolborane (HBpin, pin=pinacolate) has been carried out leading to arylboronic esters in moderate to good yields. 相似文献
90.
Biopolymer films and the effects of added lipids,nanoparticles and antimicrobials on their mechanical and barrier properties: a review 下载免费PDF全文
Javier Castro‐Rosas Andres M. Cruz‐Galvez Carlos Alberto Gomez‐Aldapa Reyna N. Falfan‐Cortes Fabiola Araceli Guzman‐Ortiz Maria Luisa Rodríguez‐Marín 《International Journal of Food Science & Technology》2016,51(9):1967-1978
Packaging made from biodegradable biopolymers such as proteins, polysaccharides and lipids is a promising alternative to synthetic polymers. Films made from these biopolymers exhibit certain disadvantages in terms of their mechanical, barrier and physicochemical properties. Plasticisers, nanoparticles, lipids and antimicrobial compounds can be added to them to improve these properties. The tendency of biopolymer films to brittleness can be mitigated by adding plasticisers and/or nanoparticles. These films also tend to have high water vapour permeability, which can be reduced by adding lipids and/or nanoparticles. Incorporating natural compounds with antimicrobial activity into biopolymer films can provide them the advantages of maintaining food safety and extending shelf life. Addition of plasticisers, nanoparticles, lipids and/or antimicrobial compounds to biopolymer films can help to make them comparable to conventional synthetic films with the advantages that they reduce pollution and are biodegradable. 相似文献