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   162篇
  免费   5篇
  国内免费   3篇
化学   83篇
晶体学   12篇
力学   5篇
数学   49篇
物理学   21篇
  2023年   1篇
  2022年   10篇
  2021年   4篇
  2020年   1篇
  2019年   2篇
  2018年   5篇
  2017年   2篇
  2016年   8篇
  2015年   4篇
  2014年   3篇
  2013年   20篇
  2012年   7篇
  2011年   6篇
  2010年   7篇
  2009年   4篇
  2008年   4篇
  2007年   6篇
  2006年   3篇
  2005年   6篇
  2004年   7篇
  2003年   2篇
  2002年   8篇
  2001年   4篇
  2000年   6篇
  1999年   10篇
  1998年   10篇
  1997年   1篇
  1996年   4篇
  1995年   1篇
  1994年   2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
  1986年   1篇
  1984年   1篇
排序方式: 共有170条查询结果,搜索用时 15 毫秒
131.
Journal of Solid State Electrochemistry - Magnetite-carbon nanocomposite was grown in situ on nickel foam by a novel auto-combustion method, and it was investigated for application as a...  相似文献   
132.
133.
A new monophosphate Na1.28Ni0.86Fe2(PO4)3 has been synthesized by a flux method and structurally characterized by single-crystal X-ray diffraction. The compound crystallizes in the orthorhombic space group Ibmm with the parameters: a = 6.438(2) Å, b = 10.515(3) Å, c = 13.166(3) Å, Z = 4. The structure is built up from Fe2O10 units of edge-sharing FeO6 octahedra, which are connected through the corners of MO6 (M = Ni2+ or a vacancy) octahedra and PO4 tetrahedra to form a three-dimensional framework analogous to that of -CrPO4. Of the two crystallographically distinct Na+ sites contained in this structure, one is totally filled whereas the other is 28% occupied.  相似文献   
134.

Let R be a graded ring and n ? 1 be an integer. We introduce and study the notions of Gorenstein n-FP-gr-injective and Gorenstein n-gr-flat modules by using the notion of special finitely presented graded modules. On n-gr-coherent rings, we investigate the relationships between Gorenstein n-FP-gr-injective and Gorenstein n-gr-flat modules. Among other results, we prove that any graded module in R-gr (or gr-R) admits a Gorenstein n-FP-gr-injective (or Gorenstein n-gr-flat) cover and preenvelope, respectively.

  相似文献   
135.
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   
136.
RK Das  AR Panda  RK Sahoo  MR Swain 《Pramana》2002,58(3):551-561
The semileptonic decay width of heavy baryons such as (Λ b → Λcev) has been estimated in the framework of a nonrelativistic field theoretic quark model where four component quark field operators along with a harmonic oscillator wave function are used to describe translationally invariant hadronic states. The present estimation does not make an explicit use of heavy quark symmetry and has a reasonable agreement with the experimentally measured decay width, polarisation ratio and form factors with the harmonic oscillator radii and quark momentum distribution inside the hadron as free parameters.  相似文献   
137.
138.
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   
139.
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   
140.
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   
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