全文获取类型
收费全文 | 234篇 |
免费 | 13篇 |
国内免费 | 3篇 |
专业分类
化学 | 159篇 |
晶体学 | 3篇 |
力学 | 9篇 |
数学 | 32篇 |
物理学 | 47篇 |
出版年
2023年 | 1篇 |
2022年 | 3篇 |
2021年 | 6篇 |
2020年 | 6篇 |
2019年 | 2篇 |
2018年 | 10篇 |
2017年 | 9篇 |
2016年 | 11篇 |
2015年 | 10篇 |
2014年 | 16篇 |
2013年 | 14篇 |
2012年 | 9篇 |
2011年 | 20篇 |
2010年 | 22篇 |
2009年 | 11篇 |
2008年 | 16篇 |
2007年 | 10篇 |
2006年 | 14篇 |
2005年 | 6篇 |
2004年 | 6篇 |
2003年 | 10篇 |
2002年 | 4篇 |
2001年 | 7篇 |
1999年 | 4篇 |
1998年 | 3篇 |
1997年 | 2篇 |
1996年 | 5篇 |
1995年 | 3篇 |
1994年 | 6篇 |
1992年 | 1篇 |
1991年 | 1篇 |
1988年 | 1篇 |
1903年 | 1篇 |
排序方式: 共有250条查询结果,搜索用时 515 毫秒
61.
Ismail Değirmencioğlu Serdar Karaböcek Nevin Karaböcek Mustafa Er Kerim Serbest 《Monatshefte für Chemie / Chemical Monthly》2003,134(6):875-881
Summary. A novel metal-free phthalocyanine and its nickel(II) and copper(II) phthalocyaninato complexes were prepared. The new compounds
were characterized by elemental analyses, 1H- and 13C-NMR, IR, UV-Vis, and mass spectral data. The NMR and/or UV-Vis spectra of these compounds showed extremely broad bands and/or
peaks. This phenomenon seems to be related to the presence of the sulfur substituents, which is consistent with the data observed
for similar compounds. The absorption spectra of these compounds were greatly affected by aggregation processes.
Corresponding author. E-mail: dismail@ktu.edu.tr
Received July 24, 2002; accepted August 2, 2002
Published online April 7, 2003 相似文献
62.
63.
The first total synthesis of (4E,6E)-1,7-bis(3,4-dihydroxyphenyl)-hepta-4,6-dien-3-one and an alternative synthesis of (4E,6E)-1,7-bis(4-hydroxyphenyl)-hepta-4,6-dien-3-one, two natural diarylheptanoids, mainly based on Claisen–Schmidt condensation were described. The crucial steps of the syntheses were the condensation of OH-protected 4-aryl-2-butanones with OH-protected 3-aryl-acrylaldehydes by the in situ enamination and then deprotection of OH groups to give the corresponding natural diarylheptanoids. 相似文献
64.
65.
In this paper we prove new complete monotonicity properties of some functions involving the gamma function. As consequences of them we establish various new upper and lower bounds for the gamma function and the harmonic numbers. 相似文献
66.
67.
A new gradient elasticity formulation is proposed for a one-dimensional linear elastic inhomogeneous rod. In the new formulation, similar to the differential relation between the local strain and the gradient enhanced strain in the classical models of gradient elasticity, a differential relation is proposed for the Young’s modulus. Analytical and finite element solutions of the proposed formulation are derived. Results of the proposed model are compared with a classical model of gradient elasticity for a model problem of carbon nanotube reinforced polymer composite. 相似文献
68.
George Agelis Panagiota Roumelioti Amalia Resvani Serdar Durdagi Maria-Eleni Androutsou Konstantinos Kelaidonis Demetrios Vlahakos Thomas Mavromoustakos John Matsoukas 《Journal of computer-aided molecular design》2010,24(9):749-758
A new 1,5 disubstituted imidazole AT1 Angiotensin II (AII) receptor antagonist related to losartan with reversion of butyl and hydroxymethyl groups at the 2-,
5-positions of the imidazole ring was synthesized and evaluated for its antagonist activity (V8). In vitro results indicated that the reorientation of butyl and hydroxymethyl groups on the imidazole template of losartan
retained high binding affinity to the AT1 receptor concluding that the spacing of the substituents at the 2,5- positions is of primary importance. The docking studies
are confirmed by binding assay results which clearly show a comparable binding score of the designed compound V8 with that of the prototype losartan. An efficient, regioselective and cost effective synthesis renders the new compound as
an attractive candidate for advanced toxicological evaluation and a drug against hypertension. 相似文献
69.
A concept, complementary to that of hard and soft acid–base interactions (HSAB‐dominant chemisorption) and consistent with dominant physisorption to a semiconductor interface, is presented. We create a matrix of sensitivities and interactions with several basic gases. The concept, based on the reversible interaction of hard‐acid surfaces with soft bases, hard‐base surfaces with soft acids, or vice versa, corresponds 1) to the inverse of the HSAB concept and 2) to the selection of a combination of semiconductor interface and analyte materials, which can be used to direct a physisorbed vs chemisorbed interaction. The technology, implemented on nanopore coated porous silicon micropores, results in the coupling of acid–base chemistry with the depletion or enhancement of majority carriers in an extrinsic semiconductor. Using the inverse‐HSAB (IHSAB) concept, significant and predictable changes in interface sensitivity for a variety of gases can be implemented. Nanostructured metal oxide particle depositions provide selectivity and complement a highly efficient electrical contact to a porous silicon nanopore covered microporous interface. The application of small quantities (much less than a monolayer) of nanostructured metals, metal oxides, and catalysts which focus the physisorbtive and chemisorbtive interactions of the interface, can be made to create a range of notably higher sensitivities for reversible physisorption. This is exemplified by an approach to reversible, sensitive, and selective interface responses. Nanostructured metal oxides developed from electroless gold (AuxO), tin (SnO2), copper (CuxO), and nickel (NiO) depositions, nanoalumina, and nanotitania are used to demonstrate the IHSAB concept and provide for the detection of gases, including NH3, PH3, CO, NO, and H2S, in an array‐based format to the sub‐ppm level. 相似文献
70.
The violated supersymmetry property of the pairing interaction between nucleons were restored using the Pyatov method [Pyatov
and Salamov, Nucleonica
22, 127 (1977)]. The eigenvalues and eigenfunctions of the restored Hamiltonian with the separable residual Gamow-Teller effective
interactions in the particle-hole and particle-particle channels were solved within the framework of proton-neutron quasirandom
phase approximation (pnQRPA). The Gamow-Teller resonance energies for 112–124Sb isotopes and the differential cross-sections for Sn(3He, t)Sb reactions at E(3He) = 200 MeV occurring by the excitation of the Gamow-Teller resonance state were calculated. The calculated values were
compared with other calculations and the corresponding experimental data. 相似文献