全文获取类型
收费全文 | 172篇 |
免费 | 3篇 |
专业分类
化学 | 79篇 |
力学 | 2篇 |
数学 | 8篇 |
物理学 | 86篇 |
出版年
2022年 | 2篇 |
2020年 | 3篇 |
2019年 | 1篇 |
2018年 | 5篇 |
2017年 | 1篇 |
2015年 | 2篇 |
2014年 | 1篇 |
2013年 | 3篇 |
2012年 | 4篇 |
2011年 | 5篇 |
2010年 | 2篇 |
2009年 | 1篇 |
2008年 | 7篇 |
2007年 | 14篇 |
2006年 | 8篇 |
2005年 | 14篇 |
2004年 | 10篇 |
2003年 | 4篇 |
2002年 | 5篇 |
2001年 | 3篇 |
2000年 | 4篇 |
1999年 | 6篇 |
1998年 | 3篇 |
1997年 | 2篇 |
1996年 | 7篇 |
1995年 | 3篇 |
1994年 | 5篇 |
1993年 | 2篇 |
1992年 | 6篇 |
1991年 | 4篇 |
1990年 | 3篇 |
1989年 | 5篇 |
1988年 | 2篇 |
1987年 | 1篇 |
1986年 | 1篇 |
1985年 | 2篇 |
1984年 | 1篇 |
1983年 | 1篇 |
1981年 | 2篇 |
1980年 | 3篇 |
1979年 | 1篇 |
1978年 | 2篇 |
1977年 | 1篇 |
1976年 | 2篇 |
1975年 | 2篇 |
1973年 | 1篇 |
1971年 | 2篇 |
1969年 | 2篇 |
1944年 | 1篇 |
1943年 | 2篇 |
排序方式: 共有175条查询结果,搜索用时 15 毫秒
71.
Honglei Wang Dr. Yunfei Jiao Bing Wu Dr. Dong Wang Yueqi Hu Prof. Dr. Fei Liang Dr. Chen Shen Dr. Andrea Knauer Prof. Dr. Dan Ren Dr. Hongguang Wang Prof. Dr. Peter A. van Aken Prof. Dr. Hongbin Zhang Prof. Dr. Zdenek Sofer Prof. Dr. Michael Grätzel Prof. Dr. Peter Schaaf 《Angewandte Chemie (International ed. in English)》2023,62(17):e202217253
Two-dimensional (2D) materials catalysts provide an atomic-scale view on a fascinating arena for understanding the mechanism of electrocatalytic carbon dioxide reduction (CO2 ECR). Here, we successfully exfoliated both layered and nonlayered ultra-thin metal phosphorous trichalcogenides (MPCh3) nanosheets via wet grinding exfoliation (WGE), and systematically investigated the mechanism of MPCh3 as catalysts for CO2 ECR. Unlike the layered CoPS3 and NiPS3 nanosheets, the active Sn atoms tend to be exposed on the surfaces of nonlayered SnPS3 nanosheets. Correspondingly, the nonlayered SnPS3 nanosheets exhibit clearly improved catalytic activity, showing formic acid selectivity up to 31.6 % with −7.51 mA cm−2 at −0.65 V vs. RHE. The enhanced catalytic performance can be attributed to the formation of HCOO* via the first proton-electron pair addition on the SnPS3 surface. These results provide a new avenue to understand the novel CO2 ECR mechanism of Sn-based and MPCh3-based catalysts. 相似文献
72.
Abstract In isotope geochemistry, natural differences in isotope abundance ratios of heavy elements (e.g. Sr, Nd, Pb) allow the use of specific isotopic signatures as tracers for these and genetically related elements. Examples of such applications in the field of anthropogeochemistry will be presented for lead and strontium. 相似文献
73.
Jennifer Rodon Fores Miryam Criado‐Gonzalez Alain Chaumont Alain Carvalho Christian Blanck Marc Schmutz Christophe A. Serra F. Boulmedais Pierre Schaaf Loïc Jierry 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(52):18993-18998
Inspired by biology, one current goal in supramolecular chemistry is to control the emergence of new functionalities arising from the self‐assembly of molecules. In particular, some peptides can self‐assemble and generate exceptionally catalytically active fibrous networks able to underpin hydrogels. Unfortunately, the mechanical fragility of these materials is incompatible with process developments, relaying this exciting field to academic curiosity. Here, we show that this drawback can be circumvented by enzyme‐assisted self‐assembly of peptides initiated at the walls of a supporting porous material. We applied this strategy to grow an esterase‐like catalytically active supramolecular hydrogel (CASH) in an open‐cell polymer foam, filling the whole interior space. Our supported CASH material is highly efficient towards inactivated esters and enables the kinetic resolution of racemates. This hybrid material is robust enough to be used in continuous flow reactors, and is reusable and stable over months. 相似文献
74.
F. Rose O. Schulte P. Schaaf W. Lohstroh W. Felsch 《Applied Physics A: Materials Science & Processing》1996,63(2):183-190
The structural and magnetic properties of La/Fe multilayers were investigated by X-ray diffraction, RHEED, magnetometry and57Fe Mössbauer spectroscopy. Comparison is made with previous results obtained for Ce/Fe multilayers. Remarkably sharp interfaces are found, with roughness between 2 and 2.5 Å. The magnetic interface in the Fe sublayers resulting from the distribution of magnetic hyperfine fields distinctly exceeds the extension of the structural interface and points to a magnetic proximity effect. This is discussed in relation to a strong 3d-5d hybridization recently found in measurements of magnetic circular X-ray dichroism. Both the structural and magnetic La/Fe interface is less extended than the interface in Ce/Fe multilayers. Below a thickness of about 25 Å, the individual Fe layers grow in an amorphous structure on the La layers. In this case, Curie temperatures are below 200 K and the Fe-layer saturation magnetization is reduced up to 50%, and there is evidence of a non-collinear spin structure. It is argued that this mainly reflects the properties of pure amorphous Fe. 相似文献
75.
76.
77.
The setup for Simultaneous Triple Radiation Mössbauer Spectroscopy (STRMS) is described. The arrangement allows an independent and simultaneous recording of conversion electron Mössbauer spectra (CEMS) and of conversion X-ray Mössbauer spectra (CXMS), both in backscattering geometry, and-in addition-of γ-ray absorption spectra in transmission (TMS). Due to the different escape or penetration ranges of the three radiations involved, the spectra give information on phases, depth and orientation. From a practical point of view the counter for γ-rays, X-rays and electrons must be separated and shielded to minimize the mutual perturbation. 相似文献
78.
79.
Dhar S. Schaaf P. Bibić N. Hooker E. Milosavljević M. Lieb K.P. 《Applied Physics A: Materials Science & Processing》2003,76(5):773-780
Applied Physics A - Silicide formation and ion beam mixing of Fe/Si bilayers due to Ar-, Xe- and Au-ion irradiations at room and liquid-nitrogen temperatures were investigated. For the study of... 相似文献
80.
P. Schaaf A. Emmel E. Schubert H. W. Bergmann K. P. Lieb 《Hyperfine Interactions》1994,92(1):1361-1366
Steel plates (St 14-05) of 1.5 mm thickness and coated with 1.5 m of ironzinc-phosphatehydrate (ASTM 29-1429) were irradiated with an XeCl-excimer laser (Siemens XP 2020) at energy densities of 20–80 mJ/mm2 and with 2–32 pulses per spot. Depth-sensitive Mössbauer spectroscopy was carried out by means of conversion electron (CEMS) and conversion X-ray (CXMS) Mössbauer spectroscopy in order to determine the phases produced by the excimer laser treatment. Although the phosphate layer is mainly ablated during the laser treatment, there is a significant formation of Fe2P. The phosphorous phase and the wüstite, with changing stoichiometries, were found in the very surface (CEMS). In deeper layers and in correlation with the energy density and the number of pulses, austenite was found in surprisingly high amounts (CEMS and CXMS). The austenite was found to be nitrogen austenite. The high Fe-N austenite content as well as the presence of some ferromagnetic Fe-N phase (-Fe2+xN) must be ascribed to an unexpectedly high nitriding effect during the laser treatment. 相似文献