全文获取类型
收费全文 | 134篇 |
免费 | 4篇 |
国内免费 | 2篇 |
专业分类
化学 | 68篇 |
力学 | 4篇 |
数学 | 44篇 |
物理学 | 24篇 |
出版年
2023年 | 2篇 |
2022年 | 2篇 |
2021年 | 4篇 |
2020年 | 5篇 |
2019年 | 6篇 |
2018年 | 6篇 |
2017年 | 1篇 |
2016年 | 7篇 |
2015年 | 6篇 |
2014年 | 2篇 |
2013年 | 10篇 |
2012年 | 7篇 |
2011年 | 7篇 |
2010年 | 7篇 |
2009年 | 10篇 |
2008年 | 9篇 |
2007年 | 7篇 |
2006年 | 6篇 |
2005年 | 2篇 |
2004年 | 3篇 |
2003年 | 3篇 |
2002年 | 2篇 |
2001年 | 2篇 |
2000年 | 3篇 |
1998年 | 1篇 |
1997年 | 1篇 |
1996年 | 1篇 |
1995年 | 3篇 |
1992年 | 2篇 |
1990年 | 1篇 |
1988年 | 4篇 |
1985年 | 2篇 |
1984年 | 2篇 |
1983年 | 1篇 |
1981年 | 1篇 |
1975年 | 1篇 |
1974年 | 1篇 |
排序方式: 共有140条查询结果,搜索用时 31 毫秒
1.
Template reactions of 2,4-dihydroxy-, 2,5-dihydroxy-, 2-hydroxy-3-methoxy- and 2-hydroxy-4-methoxy-benzaldehyde with methoxy- and hydroxy-substituted salicylaldehyde S-methylthiosemicarbazones in the presence of NiCl2 and FeCl3 resulted in the corresponding hydroxy- and methoxy-substituted N1,N4-diarylidene-S-methylthiosemi-carbazone complexes. Characterization of the compounds, [Fe(L)Cl] and [Ni(L)], was accomplished by means of elemental analysis, conductivity and magnetic measurements, i.r. and 1H-n.m.r. spectra. A systematic trend has been observed for the chemical shift values of the aromatic protons in the spectra of complexes. 相似文献
2.
Güveli Şükriye Özdemir Namık Bal-Demirci Tülay Soylu Mustafa Serkan Ülküseven Bahri 《Transition Metal Chemistry》2019,44(2):115-123
Transition Metal Chemistry - Mixed ligand Ni(II) complexes were synthesized from triphenylphosphine and S-methyl- or S-ethyl-isothiosemicarbazone ligands derived from... 相似文献
3.
Clear evidence for symplectic symmetry in low-lying states of 12C and 16O is reported. Eigenstates of 12C and 16O, determined within the framework of the no-core shell model using the J-matrix inverse scattering potential with A相似文献
4.
5.
6.
7.
Anthony Bahri Martin Bendersky 《Transactions of the American Mathematical Society》2000,352(3):1191-1202
Toric manifolds, a topological generalization of smooth projective toric varieties, are determined by an -dimensional simple convex polytope and a function from the set of codimension-one faces into the primitive vectors of an integer lattice. Their cohomology was determined by Davis and Januszkiewicz in 1991 and corresponds with the theorem of Danilov-Jurkiewicz in the toric variety case. Recently it has been shown by Buchstaber and Ray that they generate the complex cobordism ring. We use the Adams spectral sequence to compute the -theory of all toric manifolds and certain singular toric varieties.
8.
We describe in this paper a design procedure for omnidirectional high reflectors with wide bandwidths for optical telecommunication
bands. From the numerical results achieved by the transfer matrix method, it is found that a partial omnidirectional high-reflector
covering the optical telecommunication wavelengths 1.3 and 1.55 μm is obtained for a partially deformed quarter-wave stack
air/H(LH)15/glass by using the tellurium as a material of high refractive index (n
H = 4.6). The partially deformed stack is a periodic system deformed by a power law y = x
1+k. Here y is the coordinates of the deformed object, x is the coordinates of the periodic stack and k is the coefficient defining the deformation degree. The study of this system leads to an omnidirectional high reflector band
covering the optical telecommunication wavelengths 1.3 and 1.55 μm for k = 0.2. 相似文献
9.
M. Olszacki C. Maj M. Al Bahri P. Pons J-C. Marrot A. Napieralski 《Procedia Chemistry》2009,1(1):44-47
Absolute piezoresistive pressure sensors often use direct wafer bonding of SOI with the etched bulk silicon to provide us with sensitive membranes and sealed cavities. The advantage of such a process is that we can easily obtain a thin, monocrystalline silicon membrane with controlled thickness and a vacuum sealed cavity. However, few works have been reported on the electrical quality of this N-type membrane and its influence on performance of the P-type gauges. The problem of parasitic Boron appearance at the Si/SiO2 interface was only recently shown in BESOI wafers, but it becomes much more significant when creating the component at the bottom side of the device layer, like in the case of an absolute piezoresistive pressure sensor. 相似文献
10.
Hoi-Ming Chi Okan K. Ersoy Herbert Moskowitz Jim Ward 《European Journal of Operational Research》2007
Using a supply chain network, we demonstrate the feasibility, viability, and robustness of applying machine learning and genetic algorithms to respectively model, understand, and optimize such data intensive environments. Deployment of these algorithms, which learn from and optimize data, can obviate the need to perform more complex, expensive, and time consuming design of experiments (DOE), which usually disrupt system operations. We apply and compare the behavior and performance of the proposed machine learning algorithms to that obtained via DOE in a simulated Vendor Managed Replenishment system, developed for an actual firm. The results show that the models resulting from the proposed algorithms had strong explanatory and predictive power, comparable to that of DOE. The optimal system settings and profit were also similar to that obtained from DOE. The virtues of using machine learning and evolutionary algorithms to model and optimize data rich environments thus seem promising because they are automatic, involving little human intervention and expertise. We believe and are exploring how they can be made adaptive to improve parameter estimates with increasing data, as well as seamlessly detecting system (and therefore model) changes, thus being capable of recursively updating and reoptimizing a modified or new model. 相似文献