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   62篇
  免费   1篇
  国内免费   3篇
化学   30篇
晶体学   1篇
力学   1篇
数学   8篇
物理学   26篇
  2021年   1篇
  2018年   2篇
  2017年   1篇
  2013年   2篇
  2012年   2篇
  2010年   4篇
  2009年   1篇
  2008年   1篇
  2007年   2篇
  2006年   3篇
  2005年   4篇
  2004年   3篇
  2003年   3篇
  2000年   6篇
  1999年   3篇
  1998年   2篇
  1996年   3篇
  1995年   1篇
  1994年   2篇
  1993年   3篇
  1992年   3篇
  1991年   1篇
  1990年   3篇
  1987年   1篇
  1986年   2篇
  1985年   1篇
  1977年   1篇
  1975年   2篇
  1974年   1篇
  1973年   1篇
  1972年   1篇
排序方式: 共有66条查询结果,搜索用时 125 毫秒
1.
2.
The reactivity of the carbene stabilised indium trihydride complex, [InH3(IMes)] IMes = 1,3-dimesitylimidazol-2-ylidene, toward a variety of transition metal complexes has been investigated. The study has shown that the InH3 complex can act as a carbene and/or hydride transfer reagent to transition metal centres but does not yield heterobimetallic materials. Two new complexes, [Cp2Ti(-Cl)2Zn(IMes)Cl] and [CpNi(H)(IMes)], have resulted from this work, both of which have been spectroscopically and structurally characterised.  相似文献   
3.
4.
5.
种植沙生植物--沙棘改善内蒙古地区生态环境   总被引:2,自引:0,他引:2  
结合内蒙古地区现状,对沙棘的生物学和生态学特性、沙棘属植物化学成分和微量元素及种植沙生植物——沙棘的重要性和必要性进行了详细的研究和探讨。研究表明,沙棘属植物具有极强的生态适应性并富含多种营养成分和生物活性物质,并以耐干旱、耐瘠薄、萌蘖及固氮能力强等特点被称为治理非宜林地水土流失、改善生态环境的先锋树种。种植沙棘是治理内蒙古脆弱生态环境最经济、最有效的措施,是贫瘠的不毛之地发展经济、增加收入的经济树种。另外.种植沙棘的技术简便,容易掌握,投资少,见效快。  相似文献   
6.
以内蒙古地区沙棘果实为原料,研究了提取黄色素的工艺条件,同时对该色素的性质进行了初步探讨。结果表明,以95%的乙醇溶液作浸提剂,提取的黄色素浓度最高,工艺流程简单易行,且无毒,无污染。对提取的黄色素进行的性质试验表明,沙棘黄色素对光、热具有较好的稳定性,适用于酸性或弱碱性的食品中,葡萄糖、氧化剂(H2O2)、还原剂(Na2SO3)等食品添加剂均无明显影响以上结果为这种优良天然色素的开发与应用提供了参考。  相似文献   
7.
Cross-linking ability is possible with the oligonucleotide-tethered, monofunctional trans-Pt(II) complex shown. It was synthesized by a novel solid-phase approach comprising conjugation of immobilized tetrathymidylic acid with a trans-a(2)Pt(II) building unit, ammonolysis, and transformation of the resulting complex (R=1-N-cyclohexylmethylthyminate) into the chloro derivative (R=Cl). a=NH(2)CH(3), T=thymine.  相似文献   
8.
In a recent paper, a “distance” function, , was defined which measures the distance between pure classical and quantum systems. In this work, we present a new definition of a “distance”, D, which measures the distance between either pure or impure classical and quantum states. We also compare the new distance formula with the previous formula, when the latter is applicable. To illustrate these distances, we have used 2 × 2 matrix examples and two-dimensional vectors for simplicity and clarity. Several specific examples are calculated.  相似文献   
9.
In a successful fortification program, the stability of micronutrients added to the food is one of the most important factors. The added vitamin D3 is known to sometimes decline during storage of fortified milks, and oxidation through fatty acid lipoxidation could be suspected as the likely cause. Identification of vitamin D3 oxidation products (VDOPs) in natural foods is a challenge due to the low amount of their contents and their possible transformation to other compounds during analysis. The main objective of this study was to find a method to extract VDOPs in simulated whole milk powder and to identify these products using LTQ-ion trap, Q-Exactive Orbitrap and triple quadrupole mass spectrometry. The multistage mass spectrometry (MSn) spectra can help to propose plausible schemes for unknown compounds and their fragmentations. With the growth of combinatorial libraries, mass spectrometry (MS) has become an important analytical technique because of its speed of analysis, sensitivity, and accuracy. This study was focused on identifying the fragmentation rules for some VDOPs by incorporating MS data with in silico calculated MS fragmentation pathways. Diels–Alder derivatization was used to enhance the sensitivity and selectivity for the VDOPs’ identification. Finally, the confirmed PTAD-derivatized target compounds were separated and analyzed using ESI(+)-UHPLC-MS/MS in multiple reaction monitoring (MRM) mode.
Graphical Abstract ?
  相似文献   
10.
CSIRO has developed an ultrasonic attenuation and transit time technique and a microwave transmission technique for on-line determination of the mass flow of pneumatically conveyed solids. In a comparative plant trial on a single burner line at Bayswater power station, the ultrasonic technique determined the coal density and velocity with rms errors of 3.9 and 5.9% relative respectively; the microwave technique successfully determined the coal density with an rms error of 6.2% relative, but was unable to accurately determine solids flow velocity at the low coal densities typical of the trial. In a plant trial at a direct smelter, the microwave technique successfully determined the mass flow of pneumatically conveyed iron ore fines feeding the smelter with an rms error of 10.2% relative.  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