全文获取类型
收费全文 | 218篇 |
免费 | 2篇 |
国内免费 | 3篇 |
专业分类
化学 | 115篇 |
晶体学 | 1篇 |
力学 | 6篇 |
数学 | 50篇 |
物理学 | 51篇 |
出版年
2023年 | 2篇 |
2022年 | 4篇 |
2021年 | 5篇 |
2020年 | 5篇 |
2019年 | 5篇 |
2018年 | 1篇 |
2017年 | 2篇 |
2016年 | 4篇 |
2015年 | 5篇 |
2014年 | 7篇 |
2013年 | 12篇 |
2012年 | 10篇 |
2011年 | 14篇 |
2010年 | 5篇 |
2009年 | 4篇 |
2008年 | 7篇 |
2007年 | 10篇 |
2006年 | 14篇 |
2005年 | 6篇 |
2004年 | 9篇 |
2003年 | 7篇 |
2002年 | 7篇 |
2001年 | 4篇 |
2000年 | 6篇 |
1999年 | 8篇 |
1998年 | 8篇 |
1997年 | 3篇 |
1996年 | 5篇 |
1995年 | 3篇 |
1994年 | 2篇 |
1993年 | 4篇 |
1991年 | 2篇 |
1990年 | 3篇 |
1988年 | 2篇 |
1987年 | 1篇 |
1986年 | 2篇 |
1983年 | 1篇 |
1981年 | 5篇 |
1980年 | 3篇 |
1979年 | 4篇 |
1978年 | 1篇 |
1977年 | 1篇 |
1976年 | 4篇 |
1975年 | 1篇 |
1972年 | 1篇 |
1971年 | 1篇 |
1967年 | 1篇 |
1962年 | 1篇 |
1961年 | 1篇 |
排序方式: 共有223条查询结果,搜索用时 15 毫秒
31.
Summary Molybdena modified pure as well as sulfated ceria systems have been studied with a view to investigate their structure, surface
acidic properties and catalytic behavior for cyclohexanol decomposition reaction. The characteristics of the modified systems
were obtained from XRD measurements and acid structural properties from Temperature Programmed Desorption (TPD) of ammonia. 相似文献
32.
Spinel systems with the composition of Cu1−xZnxCr2O4 [x = 0 CCr, x = 0.25 CZCr-1, x = 0.5 CZCr-2, x = 0.75 CZCr-3 and x = 1 ZCr] were prepared by homogeneous co-precipitation
method and were characterized by X-ray diffraction (XRD) and FT-IR spectroscopy. Elemental analysis was done by EDX, and surface
area measurements by the BET method. The redox behavior of these catalysts in cyclohexane oxidation at 243 K using TBHP as
oxidant was examined. Cyclohexanone was the major product over all catalysts with some cyclohexanol. 69.2% selectivity to
cyclohexanol and cyclohexanone at 23% conversion of cyclohexane was realized over zinc chromite spinels in 10 h. 相似文献
33.
34.
Prem K. Mehrotra Jayaraman Chandrasekhar Periakaruppan T. Manoharan Sankaran Subramanian 《Chemical physics letters》1979,68(1):219-221
The nonempirical NDDO MO method in its unrestricted form has been used to evaluate isotropic hyperfine coupling constants and nuclear spin-spin coupling constants. Satisfactory agreement with INDO and experimental results is obtained. 相似文献
35.
36.
Jayaraman Chandrasekhar Prem K. Mehrotra Sankaran Subramanian Periyakaruppan T. Manoharan 《Theoretical chemistry accounts》1979,52(4):303-310
Three valence-only schemes based on the Roby version of NDDO MO theory, which differ only in the core-valence treatment and the choice of the basis set, have been applied to the study of molecules containing first-row atoms. Orbital energies, charge distribution, dipole moments, field gradients, and a few other one-electron molecular properties are calculated to satisfactory accuracy. The schemes appear unreliable in the prediction of barriers to internal rotation in molecules, presumably due to errors in the core contribution to the total energy. An alternative treatment is suggested. 相似文献
37.
38.
Morita K Sankaran NB Huang W Seino T Sato Y Nishizawa S Teramae N 《Chemical communications (Cambridge, England)》2006,(22):2376-2378
An abasic site-containing DNA combined with lumiflavin allows amperometric determination of single nucleotide polymorphism through hydrogen bond-mediated nucleobase recognition in water by using abasic sites as a molecular recognition field. 相似文献
39.
We introduce methods for visualization of data structured along trees, especially hierarchically structured collections of time series. To this end, we identify questions that often emerge when working with hierarchical data and provide an R package to simplify their investigation. Our key contribution is the adaptation of the visualization principles of focus-plus-context and linking to the study of tree-structured data. Our motivating application is to the analysis of bacterial time series, where an evolutionary tree relating bacteria is available a priori. However, we have identified common problem types where, if a tree is not directly available, it can be constructed from data and then studied using our techniques. We perform detailed case studies to describe the alternative use cases, interpretations, and utility of the proposed visualization methods. 相似文献
40.
Sankaran Viswanath 《代数通讯》2013,41(11):3903-3933
We continue the study of stabilization phenomena for Dynkin diagram sequences initiated in the earlier work of Kleber and the present author. We consider a more general class of sequences than that of this earlier work, and isolate a condition on the weights that gives stabilization of tensor product and branching multiplicities. We show that all the results of the previous article can be naturally generalized to this setting. We also prove some properties of the partially ordered set of dominant weights of indefinite Kac–Moody algebras, and use this to give a more concrete definition of a stable representation ring. Finally, we consider the classical sequences B n , C n , D n that fall outside the purview of the earlier work, and work out some easy-to-describe conditions on the weights which imply stabilization. 相似文献