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   26篇
  免费   1篇
化学   16篇
物理学   11篇
  2016年   1篇
  2014年   1篇
  2013年   1篇
  2011年   1篇
  2010年   1篇
  2007年   2篇
  2005年   1篇
  2004年   2篇
  2002年   1篇
  2001年   1篇
  2000年   3篇
  1998年   1篇
  1995年   1篇
  1994年   2篇
  1993年   1篇
  1989年   1篇
  1987年   2篇
  1986年   1篇
  1982年   1篇
  1977年   2篇
排序方式: 共有27条查询结果,搜索用时 203 毫秒
1.
ω-Vinylimines reacted with a Ti(O-i-Pr)4/2i-PrMgX reagent to generate the corresponding azatitanacyclopentanes in quantitative yield, which in turn reacted with H2O, I2 and O2 to give 2-methyl-, 2-iodomethyl-, 2-hydroxymethyl-1-aminocyclic compounds, respectively. The azatitanacyclopentanes thus generated reacted with formaldehyde to afford the corresponding 2,3-annulated pyrrolidines in good yield.  相似文献   
2.
We can perceive a surface through another surface. This perception is called transparency. It is known that transparency can be perceived even if the stimulus conditions are not consistent with physical conditions for a real transparent surface. In this study, we measured the ranges of luminance and chromaticity of the overlapping area of two crossed layers at which a surface was perceived as chromatically-uniform transparent. As the results, the luminance range of the overlapping area existed around or near the luminance of the inducing area. The upper and lower limits of the luminance range were higher for the dark background than for the light background. Moreover, the chromatic range existed around the additive colormixture line between two chromaticities of the inducing areas for both dark and light backgrounds. This indicates that the perceptual transparency mechanism would divide the color of an additive color mixture into the original colors that exist in the inducing areas. We noticed that the perceptual appearance of the stimulus changed greatly depending on the luminances of the overlapping area and the background. These differences in perceptual appearance would be a factor explaining individual difference and deciding the luminance conditions for transparency.  相似文献   
3.
1) Clinical application: Dynamic scintigraphy of liver and heart of a patient having liver cirrhosis after intrasigmoidal administration of 13N-ammonia (pH 8.1) were performed. Simultaneously, continuous measurments of radioactivity at the left side abdomen and the left temporal region were done by using a scintillation detector for renography. Successive measurement of radioactivity of blood was also carried out. 2) Comstruction of functional images of liver and heart: By using digital radioisotope image of liver and heart of the patient after intrasigmoidal administration of 13N-ammonia, the maps with respect to parameters described in the pervious paper were constructed.  相似文献   
4.
Ammonia has been known to be an inducing agent of hepatic coma associated with liver cirrhosis. In order to establish a non-invasive method of investigating the portal circulation and the metabolism of ammonia at liver the following studies were performed, by using cyclotron produced 13N-labeled ammonia and delayed line-camera interphased with on-line computer system. 1) Animal experiment. Dynamic scintigraphy of thoraco-abdominal region of a rabbit after intrasigmoidal as well as intravenous administration of 13N-ammonia were performed. 2) Theoretical consideration on the functional image of liver: According to the results of the animal experiments, a model of ammonia metabolism having the minimal complexity necessary to represent data in the case of intrasigmoidal administration was proposed. Starting from the solution to the differential equation describing the model, relevant parameters characterizing the dynamic curve of liver were duded.  相似文献   
5.
6.
As a frame work of the study for the latent track size measurement using atomic force microscope, we have measured the minute etch pits and the extremely small amount of bulk etch of CR-39 at the beginning of chemical etching, and obtained its growth curves in nanometer dimensions. The pieces of CR-39 were exposed to 6 MeV/nC and Fe ions with normal incidence angle and were etched in 70°C 7 N NaOH solution for 0.5,1,2,3,5 min. The diameters of latent track were estimated to be 17 nm for Fe ions and 8 nm for C ions, respectively. These values are comparable to the experimental data on the average ‘track core diameters’ that have been obtained by various experimental techniques.  相似文献   
7.
Sato S  Uchikawa S 《Talanta》1986,33(2):115-118
A very sensitive, selective and simple method for extraction and spectrophotometric determination of titanium(IV) with an alpha-hydroxy acid has been developed. p-Chloromandelic acid reacts with titanium in weakly acidic aqueous solution at room temperature to form a complex anion extractable into chlorobenzene with Malachite Green as counter-ion. Titanium is determined indirectly by measuring the absorbance of Malachite Green in the extract at 630 nm. The calibration graph is linear for titanium(IV) over the range 0.25-7.5muM (0.05-1.44 mug); the apparent molar absorptivity is 1.31 x 10(5) l.mole(-1).cm(-1). The method has been successfully applied to the determination of titanium in mild steels.  相似文献   
8.
9.
Sato S  Iwamoto M  Uchikawa S 《Talanta》1987,34(4):419-422
Molybdenum(VI) reacts with p-chloromandelic acid to form a complex extractable into chlorobenzene with Malachite Green, from aqueous solution at pH 2.0-4.0 at room temperature, and can then be determined indirectly by measuring the absorbance of the Malachite Green in the extract, at 630 nm. The calibation graph is linear for molybdenum over the range 0.26-10.0 x 10(-6)M (0.10-4.0 mug); the apparent molar absorptivity is 1.06 x 10(5) l.mole(-1).cm(-1). The method has been applied to the determination of molybdenum in mild steels with satisfactory results.  相似文献   
10.
The Tl-Ba-Ca-Cu-O superconducting ceramics containing Al2O3 have been prepared utilizing the reaction, Tl2O2+BaCuO2+Ca2CuO3+A12O3 or Tl2O3+BaCuO2 +Ca2CuO3+AlCuO2.5. It is shown that the resulting ceramics show the superconductivity at temperatures over 100 K when the Al/Cu molar ratio is kept below 0.5. EPMA analyses revealed that there is always an Al2BaO4 layer between the superconducting Tl-Ba-Ca-Cu-O and Al2O3 phases, leading to the separation between the superconducting and A12O3 phases.  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