全文获取类型
收费全文 | 127篇 |
免费 | 5篇 |
专业分类
化学 | 101篇 |
数学 | 11篇 |
物理学 | 20篇 |
出版年
2023年 | 2篇 |
2021年 | 2篇 |
2019年 | 2篇 |
2018年 | 1篇 |
2017年 | 1篇 |
2016年 | 3篇 |
2015年 | 1篇 |
2014年 | 5篇 |
2013年 | 7篇 |
2012年 | 3篇 |
2011年 | 9篇 |
2010年 | 2篇 |
2009年 | 2篇 |
2008年 | 6篇 |
2007年 | 2篇 |
2005年 | 3篇 |
2004年 | 5篇 |
2003年 | 1篇 |
2002年 | 2篇 |
2001年 | 3篇 |
2000年 | 4篇 |
1999年 | 1篇 |
1995年 | 1篇 |
1994年 | 1篇 |
1993年 | 2篇 |
1992年 | 2篇 |
1991年 | 3篇 |
1990年 | 1篇 |
1989年 | 2篇 |
1988年 | 1篇 |
1987年 | 6篇 |
1986年 | 3篇 |
1985年 | 4篇 |
1984年 | 7篇 |
1983年 | 5篇 |
1982年 | 3篇 |
1981年 | 5篇 |
1980年 | 5篇 |
1979年 | 1篇 |
1977年 | 1篇 |
1970年 | 1篇 |
1964年 | 1篇 |
1963年 | 1篇 |
1962年 | 4篇 |
1943年 | 1篇 |
1939年 | 1篇 |
1935年 | 2篇 |
1914年 | 1篇 |
排序方式: 共有132条查询结果,搜索用时 15 毫秒
1.
Hongmin Wang Shuting Fu Bo Shang Sungho Jeon Yiren Zhong Nia J. Harmon Chungseok Choi Eric A. Stach Hailiang Wang 《Angewandte Chemie (International ed. in English)》2023,62(30):e202305251
Photothermal CO2 reduction is one of the most promising routes to efficiently utilize solar energy for fuel production at high rates. However, this reaction is currently limited by underdeveloped catalysts with low photothermal conversion efficiency, insufficient exposure of active sites, low active material loading, and high material cost. Herein, we report a potassium-modified carbon-supported cobalt (K+−Co−C) catalyst mimicking the structure of a lotus pod that addresses these challenges. As a result of the designed lotus-pod structure which features an efficient photothermal C substrate with hierarchical pores, an intimate Co/C interface with covalent bonding, and exposed Co catalytic sites with optimized CO binding strength, the K+−Co−C catalyst shows a record-high photothermal CO2 hydrogenation rate of 758 mmol gcat−1 h−1 (2871 mmol gCo−1 h−1) with a 99.8 % selectivity for CO, three orders of magnitude higher than typical photochemical CO2 reduction reactions. We further demonstrate with this catalyst effective CO2 conversion under natural sunlight one hour before sunset during the winter season, putting forward an important step towards practical solar fuel production. 相似文献
2.
3.
Marek Stach Zuzana KronekováPeter Kasák Jozef KollárMartin Pentrák Matej Mi?ušíkDušan Chorvát Jr. Tim S. NunneyIgor Lacík 《Applied Surface Science》2011,257(24):10795-10801
The sulfobetaine films were prepared on stainless steel and golden surfaces. In the first step, the poly(2-(dimethylamino)ethyl methacrylate) film was created by employing the electrografting polymerization technique. In the second step, this film was modified to polysulfobetaine, i.e. the polymer film bearing the zwitterionic groups. The presence of the electrografted film and its modification were determined by contact angle measurements, infrared spectroscopy in reflectance mode and X-ray photoelectron spectroscopy. The prepared films were homogeneous with the thickness from about 5 to 26 nm as determined by X-ray photoelectron spectroscopy. The atomic force microscopy measurements showed the increase of surface roughness upon the surface coating. In vitro tests using adherent RAT-2 fibroblast cells and fluorescently labelled bovine serum albumin proteins showed that prepared polysulfobetaine films can be used in applications requiring the resistance against cell attachment and biofouling. 相似文献
4.
Ştefan Ţălu Sebastian Stach Joana Zaharieva Maria Milanova Dimitar Todorovsky Stefano Giovanzana 《International Journal of Polymer Analysis and Characterization》2014,19(5):404-421
The structural complexity of the 3-D surface of poly(methylmethacrylate) films with immobilized europium β-diketonates was studied by atomic force microscopy and fractal analysis. Fractal analysis of surface roughness revealed that the 3-D surface has fractal geometry at the nanometer scale. Poly(methylmethacrylate) (PMMA) as immobilization matrix is dense and uniform, and a tendency for formation of chain structures was observed. Fractal analysis can quantify key elements of 3-D surface roughness such as the fractal dimensions D f determined by the morphological envelopes method of the Eu(DBM)3 and Eu(DBM)3 · dpp nanostructures, which are not taken into account by traditional surface statistical parameters. 相似文献
5.
Teobald Kupka Michał Stachów Jakub Kaminsky Stephan P. A. Sauer 《Magnetic resonance in chemistry : MRC》2013,51(8):482-489
A linear correlation between isotropic nuclear magnetic shielding constants for seven model molecules (CH2O, H2O, HF, F2, HCN, SiH4 and H2S) calculated with 37 methods (34 density functionals, RHF, MP2 and CCSD(T)), with affordable pcS‐2 basis set and corresponding complete basis set results, estimated from calculations with the family of polarization‐consistent pcS‐n basis sets is reported. This dependence was also supported by inspection of profiles of deviation between CBS estimated nuclear shieldings and shieldings obtained with the significantly smaller basis sets pcS‐2 and aug‐cc‐pVTZ‐J for the selected set of 37 calculation methods. It was possible to formulate a practical approach of estimating the values of isotropic nuclear magnetic shielding constants at the CCSD(T)/CBS and MP2/CBS levels from affordable CCSD(T)/pcS‐2, MP2/pcS‐2 and DFT/CBS calculations with pcS‐n basis sets. The proposed method leads to a fairly accurate estimation of nuclear magnetic shieldings and considerable saving of computational efforts. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
6.
7.
The adsorption equilibrium of water on microporous adsorbents (zeolites of NaA-, NaY- and NaX-type as well as their ion exchanged
forms) and on mesoporous adsorbents (different silica gels and composite material i.e. silica gel + salt hydrate) has been
studied experimentally and theoretically. Using the Dubinin theory of pore filling the characteristic curves of the adsorption
systems and other relevant dependences such as isotherms, isobars, isosteres and the curve of the differential heat of adsorption
were calculated. For all systems investigated the adsorption were calculated. Aads and the desorption potential Ades of the closed heat storage system were estimated. These values define the working range of the adsorption/desorption cycle
and allow to calculate the specific heat storage density Δ hsp. On the basis of Δ hsp the different adsorbents were compared in order to select the optimal porous storage material for a given application.
The presented experimental and theoretical investigations show that the adsorption systems water-zeolite and water-composites
are promising working pairs for thermochemical heat storage processes for hot tap water supply and space heating of single
family dwellings. The advantage of the water-composite system is the low desorption temperature (solar energy) the main shortcoming
the low temperature lift. The advantage of the water zeolite system is the high temperature lift, the shortcoming are the
relative high desorption temperatures. 相似文献
8.
The flaws in the Reply [1] to our paper [2] have been pointed out. Elber and Karplus (EK) have not disproved our irrefutable global statement that the energy average cannot be minimized which rebuts the theoretical background of EK-type calculations. Another statement of ours has shown that even a curve for which the average energy is locally minimal for all directional perturbations in the sense of classical variational calculus cannot be identical with the reaction path (RP) defined as a steepest descent path (SDP). EK found an error in the early preprint of our theoretical paper [3] and because of this error they qualified our correct variational statement as false for all the SDPs consisting of a straight line each. Mixing global and variational arguments, EK refuted our criticism in a logically incorrect manner. In this Comment we prove that both of our earlier statements invariably remain in force and the criticism included in those has been as well-established and solid as was before. 相似文献
9.
10.
Thomas Drewello Rainer Herzschuh Joachim Stach 《Zeitschrift für Physik D Atoms, Molecules and Clusters》1993,28(4):339-343
A triple stage hybrid mass spectrometer was scanned for the trapping of the reaction intermediates of the over-all loss of two CsI-moieties from size-selected caesium iodide cluster ions of the general formula Cs (CsI)+ n . In addition to appropriate MS/MS/MS-methods an electrically floated collision cell has been applied to trap intermediates of unimolecular and collision-induced evaporations. In comparison with other experimental findings the features of the evaporation mechanism are discussed. 相似文献