首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   153篇
  免费   5篇
  国内免费   2篇
化学   87篇
晶体学   11篇
力学   5篇
数学   44篇
物理学   13篇
  2023年   1篇
  2022年   11篇
  2021年   4篇
  2020年   1篇
  2019年   3篇
  2018年   4篇
  2017年   4篇
  2016年   9篇
  2015年   4篇
  2014年   3篇
  2013年   20篇
  2012年   8篇
  2011年   5篇
  2010年   6篇
  2009年   5篇
  2008年   4篇
  2007年   4篇
  2006年   3篇
  2005年   6篇
  2004年   7篇
  2003年   2篇
  2002年   5篇
  2001年   3篇
  2000年   4篇
  1999年   9篇
  1998年   8篇
  1997年   1篇
  1996年   3篇
  1995年   1篇
  1994年   1篇
  1993年   1篇
  1991年   2篇
  1990年   2篇
  1989年   1篇
  1988年   3篇
  1987年   1篇
  1984年   1篇
排序方式: 共有160条查询结果,搜索用时 46 毫秒
131.
This paper examines the effect of the granulation process on the color texture of compacted powders and granules. The objective is to obtain information to provide for a better comprehension of granulation mechanisms by using a pigment as a texture marker. This requires the establishment of a methodology both to qualify and quantify the spatial variation of color on the compact surface. This is achieved by color image analysis accompanied by both a statistical and a spatial treatment of the color content in the images.  相似文献   
132.
133.
134.
The popularity of fruits vinegar (FsV) has been increased recently as a healthy drink wealthy in bioactive compounds that provide several beneficial properties. This review was designed in the frame of valorization of fruits vinegar as a by-product with high value added by providing overall information on its biochemical constituents and beneficial potencies. It contains a cocktail of bioactive ingredients including polyphenolic acids, organic acids, tetramethylperazine, and melanoidins. Acetic acid is the most abundant organic acid and chlorogenic acid is the major phenol in apple vinegar. The administration of fruits vinegar could prevent diabetes, hypercholesterolemia, oxidative stress, cancer, and boost immunity as well as provide a remarkable antioxidant ability. The production techniques influence the quality of vinegar, and consequently, its health benefits.  相似文献   
135.
The main objective of the current study was to determine the physicochemical properties, antioxidant activities, and α-glucosidase and α-amylase inhibition of apple vinegar produced by artisanal and industrial methods. Apple vinegar samples were analyzed to identify their electrical conductivity, pH, titratable acidity, total dry matter, Brix, density, mineral elements, polyphenols, flavonoids, and vitamin C. The antioxidant activity of apple vinegar samples was evaluated using two tests, total antioxidant capacity (TAC) and DPPH radical scavenging activity. Finally, we determined α-glucosidase and α-amylase inhibitory activities of artisanal and industrial apple vinegar. The results showed the following values: pH (3.69–3.19); electrical conductivity (2.81–2.79 mS/cm); titratable acidity (3.6–5.4); ash (4.61–2.90); °Brix (6.37–5.2); density (1.02476–1.02012), respectively, for artisanal apple vinegar and industrial apple vinegar. Concerning mineral elements, potassium was the most predominant element followed by sodium, magnesium, and calcium. Concerning bioactive compounds (polyphenols, flavonoids, and vitamin C), the apple vinegar produced by the artisanal method was the richest sample in terms of bioactive compounds and had the highest α-glucosidase and α-amylase inhibition. The findings of this study showed that the quality and biological activities of artisanal apple vinegar were more important than industrial apple vinegar.  相似文献   
136.
In the title compound, disodium cobalt tetrakis­(dihydrogen­phosphate) tetrahydrate, the CoII ion lies on an inversion centre and is octahedrally surrounded by two water molecules and four H2PO4 groups to give a cobalt complex anion of the form [Co(H2PO4)4(OH2)]2?. The three‐dimensional framework results from hydrogen bonding between the anions. The relationship with the structures of Co(H2PO4)2·2H2O and K2CoP4O12·5H2O is discussed.  相似文献   
137.
The title compound, N,N,N′,N′‐tetra­methyl­ethyl­enedi­ammon­ium di­aqua­(arsenate)­(hydrogen arsenate)­dizinc(II), (C6H18N2)0.5[Zn2(AsO4)(HAsO4)(H2O)2], is a new zincoarsenate obtained by hydro­thermal synthesis. The structure consists of infinite two‐dimensional anionic layers alternating with planes containing centrosymmetric organic diprotonated template N,N,N′,N′‐tetra­methyl­ethyl­enedi­ammonium cations, [H3N­C6H12NH3]2+. The latter are interconnected to the framework through hydrogen bonds.  相似文献   
138.
139.
The tetrabutylammonium salt of mononiobotungstate [(n-C4H9)4N]3NbW5O19 (1) and the tetrabutylammonium salt of monovanadotungstate [(n-C4H9)4N]3VW5O19 (2) are isotypes; both crystallize in the monoclinic system, space group C2/c (N° 15) with Z=8. The cell parameters for 1 are a=30.4038(8) ?, b=18.5948(8) ?, c=27.3330(3) ?, β=112.4555(6)°, V=14281.1(7) ?3 and the final reliability factors are R=0.043 and R w=0.047 for 5801 reflections. The cell parameters for 2 are a=30.096(8) ?, b=18.373(3) ?, c= 27.201(6) ?, β=112.402(14)°, V=13906(5) ?3 and the final reliability factors are R=0.048 and R w=0.054 for 6122 reflections. Both anions, [NbW5O19] 3− and [VW5O19] 3− exhibit the Lindqvist structure of the parent hexatungstate anion. The six metal positions are disordered and for each metal site the occupation factor is close to 1/6 M (M=Nb, V) and 5/6 W. Furthermore the two compounds were characterized by IR in the solid state, and 183W solution NMR. The 183W spectrum of [NbW5O19] 3− presents two resonances with relative intensities 4:1 in agreement with the C4v symmetry of the anion.  相似文献   
140.
The asymptotic behaviour of laminar forced convection for Bingham fluid in a circular tube subjected to an axially varying wall heat flux is studied analytically. The effect of viscous dissipation is taken into account while the axial heat conduction in the fluid is considered as negligible. The asymptotic temperature profile and the asymptotic Nusselt number are determined for various axial wall heat flux distributions which yield a thermally developed region. The results obtained show a diminution in asymptotic Nusselt number when the Brinkman number and the dimensionless radius of the plug flow region increase. Comparisons with the results in the literature for Newtonian fluids show the validity of the present analysis. To cite this article: R. Khatyr et al., C. R. Mecanique 330 (2002) 69–75.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号