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   91篇
  免费   2篇
  国内免费   3篇
化学   67篇
晶体学   1篇
力学   7篇
数学   15篇
物理学   6篇
  2023年   2篇
  2022年   11篇
  2021年   1篇
  2020年   5篇
  2019年   6篇
  2018年   7篇
  2017年   6篇
  2016年   4篇
  2015年   7篇
  2014年   5篇
  2013年   20篇
  2012年   6篇
  2011年   5篇
  2010年   1篇
  2009年   6篇
  2008年   2篇
  2007年   1篇
  2006年   1篇
排序方式: 共有96条查询结果,搜索用时 15 毫秒
51.
The new synthesized ligand (DADMBTZ = 2,2′‐diamino‐5,5′‐dimethyl‐4,4′‐bithiazole), which is mentioned in this text, is used for preparing the two new complexes [Zn(DADMBTZ)3](ClO4)2. 0.8MeOH.0.2H2O ( 1 ) and [Cd(DADMBTZ)3](ClO4)2 ( 2 ). The characterization was done by IR, 1H, 13C NMR spectroscopy, elemental analysis and single crystal X‐ray determination. In reaction with DADMBTZ, zinc(II) and cadmium(II) show different characterization. In 2 , to form a tris‐chelate complex with nearly C3 symmetry for coordination polyhedron, DADMBTZ acts as a bidentate ligand. In 1 , this difference maybe relevant to small radii of Zn2+ which make one of the DADMBTZ ligands act as a monodentate ligand to form the five coordinated Zn2+ complex. In both 1 and 2 complexes the anions are symmetrically different. 1 and 2 complexes form 2‐D and 3‐D networks via N‐H···O and N‐H···N hydrogen bonds, respectively.  相似文献   
52.

Abstract  

The crystal growth of (C6H14N2)[Cr2O7], consists of a diazabicyclo[2.2.2]octane-1,4-diium cation and a discrete dichromate anion, in solution has been determined under the influence of various factors. Four factors, which influence the crystal size, crystal growth and nucleation, were chosen. These factors are concentration, temperature, type of solvent and method of crystallization. Taguchi design of experiments (DOE) method has been used for to plan a minimum number of experiments and optimization of crystallization processes. Crystallization of diazabicyclo[2.2.2]octane-1,4-diium dichromate with desirable particle size, shape and minimum time of crystal growth as performance characteristics were studied. The changes in the crystal growth habit were observed and could be explained by the differences in the morphology on the various photograph of this compound.  相似文献   
53.

Lump solutions are a prominent option for numerous models of nonlinear evolution. The intention of this research is to explore the variable coefficients Kadomtsev–Petviashvili equation. We auspiciously provide multiple soliton and M-lump solutions to this equation. Additionally, the presented results are also supplied with collision phenomena. Owing of its essential role, we employ appropriate parameter values to emphasis the physical characteristics of the provided results using 3D and contour charts. The outcomes of this work convey the physical characteristics of lump and lump interactions that occur in many dynamical regimes.

  相似文献   
54.
Let R be a commutative Noetherian ring and \(\mathfrak{a}\) an ideal of R. We introduce the concept of \(\mathfrak{a}\) -weakly Laskerian R-modules, and we show that if M is an \(\mathfrak{a}\) -weakly Laskerian R-module and s is a non-negative integer such that Ext R j \((R/\mathfrak{a},H_\mathfrak{a}^i (M))\) is \(\mathfrak{a}\) -weakly Laskerian for all i < s and all j, then for any \(\mathfrak{a}\) -weakly Laskerian submodule X of \(H_\mathfrak{a}^s (M)\) , the R-module \(Hom_R (R/\mathfrak{a},H_\mathfrak{a}^s (M)/X)\) is \(\mathfrak{a}\) -weakly Laskerian. In particular, the set of associated primes of \(H_\mathfrak{a}^s (M)/X\) is finite. As a consequence, it follows that if M is a finitely generated R-module and N is an \(\mathfrak{a}\) -weakly Laskerian R-module such that \(H_\mathfrak{a}^i (N)\) (N) is \(\mathfrak{a}\) -weakly Laskerian for all i < s, then the set of associated primes of \(H_\mathfrak{a}^s (M,N)\) (M,N) is finite. This generalizes the main result of S. Sohrabi Laleh, M.Y. Sadeghi, and M.Hanifi Mostaghim (2012).  相似文献   
55.
Cellulose - Million tons of cellulosic paper have been used for insulating coils in oil-filled electrical power transformers, thereby assuring the electricity supply for our societies. The high...  相似文献   
56.
The resonance frequencies and stability of a nanobeam in a longitudinal magnetic field are investigated. To this aim, a three dimensional beam model is used in which the small-scale effect is taken into account based on the nonlocal elasticity theory. The Lorentz forces are obtained in terms of the local elastic rotations of the beam and the thermal stress due to current is modeled as an axial compressive force. Using the Galerkin method, the governing equations of motion are solved and the stability boundary of the nanobeam is determined.  相似文献   
57.
58.
A new, one-pot, efficient, three-component condensation of benzaldehyde derivatives, enolizable ketones, acetyl chloride, and acetonitrile or benzonitrile in the presence of silica-supported perchloric acid as an effective catalyst for the synthesis of β-amido carbonyl compounds is described. The present methodology offers several advantages, such as good yields, short reaction times, and simple workup procedure.  相似文献   
59.
The notion of generalized Laskerian modules was introduced recently by the authors. In this paper, we continue our investigation of such modules. Moreover, we are going to generalize some results on finiteness of associated primes of local cohomology modules to the category of generalized Laskerian modules.  相似文献   
60.
Alliances are popularly used in delivering infrastructure. However, discussion is ongoing as to what is the optimal gainshare/painshare arrangement. This paper derives a result for the optimal gainshare/painshare between risk-averse parties, where the level of aversion may range from very large to being risk neutral. The derivation is based on solving an optimization problem using concepts from agency theory. The influence of the parties’ level of risk aversion and outcome uncertainty is examined. Practitioners were engaged in a designed exercise in order to validate the approach and propositions. The paper shows that: (i) the optimal gainshare/painshare arrangement in alliances is linear in the project outcome; (ii) the optimal gain/pain share to the contractor should decrease with increasing contractor level of risk aversion and/or decreasing owner level of risk aversion; and (iii) the outcome uncertainty has no influence on the optimal gainshare/painshare. The paper provides those who write alliance contracts with recommendations on gainshare/painshare. This study casts new light on establishing optimal alliance arrangements in the construction industry.  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