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   189篇
  免费   2篇
化学   111篇
晶体学   1篇
力学   7篇
数学   37篇
物理学   35篇
  2023年   2篇
  2021年   2篇
  2018年   3篇
  2016年   10篇
  2015年   3篇
  2013年   10篇
  2012年   10篇
  2011年   5篇
  2010年   7篇
  2008年   6篇
  2007年   12篇
  2006年   6篇
  2005年   6篇
  2004年   6篇
  2003年   6篇
  2002年   7篇
  2001年   3篇
  1991年   3篇
  1990年   3篇
  1989年   1篇
  1988年   2篇
  1987年   1篇
  1986年   1篇
  1985年   3篇
  1984年   4篇
  1983年   3篇
  1982年   2篇
  1981年   4篇
  1980年   1篇
  1979年   2篇
  1978年   3篇
  1977年   3篇
  1976年   2篇
  1974年   4篇
  1973年   3篇
  1971年   1篇
  1970年   1篇
  1969年   1篇
  1968年   2篇
  1967年   4篇
  1964年   1篇
  1962年   1篇
  1961年   4篇
  1960年   4篇
  1959年   3篇
  1958年   2篇
  1957年   1篇
  1954年   5篇
  1946年   1篇
  1945年   1篇
排序方式: 共有191条查询结果,搜索用时 31 毫秒
51.
52.
53.
54.
A Chromatographic method for the separation and detection of lead, silver, and mercury by extraction with organic solvent mixture on strips or sheets of filter paper, is described. Study of various physico-chemical factors responsible for the separation of cations has been made.
Zusammenfassung Es wird eine chromatische Methode zur Trennung und Feststellung von Blei, Silber und Quecksilber durch Extraktion mittels Gemischen aus organischen Flüssigkeiten auf Papierstreifen beschrieben und die verschiedenen für die Trennwirkung verantwortlichen physikalisch-chemischen Faktoren werden betrachtet.


The thanks 01 the author are due to Dr. N. Ghatak, D. So., Chemical-Examiner to the Government of Uttar Pradesh, for his keen interest in this investigation.  相似文献   
55.
Toluene- and naphthalene-dioxygenase-catalysed sulfoxidation of nine disubstituted methylphenyl sulfides, using whole cells of Pseudomonas putida, consistently gave the corresponding enantioenriched sulfoxides. Using the P. putida UV4 mutant strain, and these substrates, differing proportions of the corresponding cis-dihydrodiol sulfides were also isolated. Evidence was found for the concomitant dioxygenase-catalysed cis-dihydroxylation and sulfoxidation of methyl para-tolyl sulfide. A simultaneous stereoselective reductase-catalysed deoxygenation of (S)-methyl para-tolyl sulfoxide, led to an increase in the proportion of the corresponding cis-dihydrodiol sulfide. The enantiopurity values and absolute configurations of the corresponding cis-dihydrodiol metabolites from methyl ortho- and para-substituted phenyl sulfides were determined by different methods, including chemoenzymatic syntheses from the cis-dihydrodiol metabolites of para-substituted iodobenzenes. Further evidence was provided to support the validity of an empirical model to predict, (i) the stereochemistry of cis-dihydroxylation of para-substituted benzene substrates, and (ii) the regiochemistry of cis-dihydroxylation reactions of ortho-substituted benzenes, each using toluene dioxygenase as biocatalyst.  相似文献   
56.
Lie symmetry method is used to perform detailed analysis on a class of KS equations. It is shown that the Lie algebra of the equation spanned by the vector fields of dilations in time and space are lost as a result of the linearity of the equation when n = 1. Symmetry reductions are carried out using each member of the optimal system. The reduced equations are further studied to obtain certain general solutions. Moreover, the conserved vectors are obtained through the application of Noether's theorem.  相似文献   
57.
Summary The separation by paper chromatography and identification of reducing sugars in urine is described.
Zusammenfassung Die papierchromatographische Trennung und Identifizierung reduzierender Zucker im Harn wird beschrieben.

Résumé On décrit la séparation par Chromatographie sur papier et l'identification des sucres réducteurs dans l'urine.
  相似文献   
58.
A layer of compressible, rotating, elastico-viscous fluid heated & soluted from below is considered in the presence of vertical magnetic field to include the effect of Hall currents. Dispersion relation governing the effect of viscoelasticity, salinity gradient, rotation, magnetic field and Hall currents is derived. For the case of stationary convection, the Rivlin-Erickson fluid behaves like an ordinary Newtonian fluid. The compressibility, stable solute gradient, rotation and magnetic field postpone the onset of thermosolutal instability whereas Hall currents are found to hasten the onset of thermosolutal instability in the absence of rotation. In the presence of rotation, Hall currents postpone/hasten the onset of instability depending upon the value of wavenumbers. Again, the dispersion relation is analyzed numerically & the results depicted graphically. The stable solute gradient and magnetic field (and corresponding Hall currents) introduce oscillatory modes in the system which were non-existent in their absence. The case of overstability is discussed & sufficient conditions for non-existence of overstability are derived.  相似文献   
59.
The properties of the low-lying excited states of53Mn have been investigated in the framework of the intermediate-coupling unified nuclear model. In the present calculations, it was assumed that three holes in the 1f 7/2 proton shell, which undergo excitations, are coupled to the quadrupole vibrations of the doubly even core. Energy levels and electromagnetic properties have been calculated. In most cases, the results are found to be in good agreement with the experimentally observed values for the low-lying excited states in53Mn. The results are also compared with those obtained from other models.  相似文献   
60.
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