全文获取类型
收费全文 | 66篇 |
免费 | 3篇 |
专业分类
化学 | 46篇 |
力学 | 5篇 |
数学 | 16篇 |
物理学 | 2篇 |
出版年
2022年 | 2篇 |
2021年 | 1篇 |
2019年 | 1篇 |
2016年 | 1篇 |
2014年 | 3篇 |
2013年 | 3篇 |
2012年 | 3篇 |
2011年 | 3篇 |
2010年 | 1篇 |
2009年 | 4篇 |
2008年 | 4篇 |
2007年 | 1篇 |
2006年 | 6篇 |
2005年 | 1篇 |
2004年 | 8篇 |
2002年 | 2篇 |
2000年 | 1篇 |
1999年 | 2篇 |
1997年 | 1篇 |
1996年 | 2篇 |
1995年 | 1篇 |
1990年 | 1篇 |
1988年 | 1篇 |
1985年 | 1篇 |
1984年 | 1篇 |
1983年 | 3篇 |
1978年 | 2篇 |
1976年 | 1篇 |
1975年 | 2篇 |
1932年 | 2篇 |
1926年 | 1篇 |
1924年 | 1篇 |
1922年 | 1篇 |
1913年 | 1篇 |
排序方式: 共有69条查询结果,搜索用时 31 毫秒
1.
Structurally Chemical Investigation of Monoammin Copper (I) Complexes : [CuNH3]2[Pt(CN)6], [CuNH3]2[Pt(CN)4] and Cu3[Co(CN)6] · 2NH3 The preparation and the properties of [CuNH3]2[Pt(CN)6], [CuNH3]2[Pt(CN)4] and Cu3[Co(CN)6] · 2NH3 are described. I.R. and Raman spectra have been recorded and assigned. According to X-ray powder diagrams, [CuNH3]2[Pt(CN)6] crystallizes in the trigonal space group D–P3 ml, a = 7.771, c = 5.988 Å, Z = 1. According to the spectroscopic and crystallographic data, it is concluded that the CuI ion is coordinated with one NH3 group and with the N atoms of the cyanometallate anions. The coordination number of the Cu+ is 4 in [CuNH3]2[Pt(CN)6] and 3 in [CuNH3]2[Pt(CN)4]. In the Cu3[Co(CN)6] · 2 NH3 complex two Cu atoms have the coordination number 2, the third Cu atom 4. 相似文献
2.
Thomas Prenveille Cyrielle Garreau Mathias Matner Dirk Dijkstra Wilhelm Oppermann Diethelm Johannsmann 《Journal of polymer science. Part A, Polymer chemistry》2019,57(5):621-629
The reactivity of urethanes based on 1,6‐hexamethylene diisocyanate (HDI) and 4,4′‐methylene diphenyl diisocyanate (MDI) was investigated at temperatures between 190 °C and 235 °C. Diurethane model compounds end‐capped with either 1‐dodecanol (D‐core‐D) or 1‐hexadecanol (H‐core‐H) were mixed and annealed at high temperature. The core was either MDI or HDI. The transurethanization reaction was followed based on the formation of the compounds (H‐core‐D). The amount of H‐core‐D and of side products, which had formed after variable annealing times, were identified with 1H NMR, FTIR, SEC, and MALDI‐TOF. Transurethanization was considerably faster for MDI‐based urethanes than for HDI‐based urethanes. Only traces of side products were formed during annealing of MDI‐based urethanes, whereas a significant amount of allophanates was formed from HDI‐based urethanes under the same conditions. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019 , 57, 621–629 相似文献
3.
Access to the Aeruginosin Serine Protease Inhibitors through the Nucleophilic Opening of an Oxabicyclo[2.2.1]heptane: Total Synthesis of Microcin SF608 下载免费PDF全文
Stefan Diethelm Corinna S. Schindler Prof. Dr. Erick M. Carreira 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(20):6071-6080
Serine proteases play key roles in many biological processes and are associated with several human diseases such as thrombosis or cancer. During the search for selective inhibitors of serine proteases, a family of linear peptides named the aeruginosins was discovered in marine cyanobacteria. We herein report an entry route into the synthetically challenging core fragment of these natural products. Starting from the common oxabicyclic building block 11 , we accessed the octahydroindole core of the aeruginosins, exemplified by the total synthesis of microcin SF608 ( 2 ). Key to the synthetic strategy is a highly efficient nucleophilic opening of an oxabicyclo[2.2.1]heptane producing the hydroindole motif of microcin SF608. Moreover, during the synthetic efforts we have observed an unusual regioselective epoxide reduction. Detailed experimental studies of this reaction led us to propose a mechanistic rationale involving intramolecular hydrogen atom delivery by a carbamate NH group to control the regioselectivity of the homolytic epoxide cleavage. 相似文献
4.
5.
V. Cofman J. Clarens W. Senften D. Tommasi B. Sjollema V. Rothmund B. Diethelm F. Foerster E. Knecht A. St?hler A. Burgstaller B. Carlson J. Gelhaar-M?nsbo O. L. Barnebey W. Ostwald O. Burchardt H. Ditz B. H. Margosches R. Luther G. V. Sammett S. B. Kuzirian und Schleicher 《Fresenius' Journal of Analytical Chemistry》1922,61(7):282-295
Ohne Zusammenfassung 相似文献
6.
We reinvestigate the sign problem in the two-dimensional Hubbard model using the projector ground state Quantum Monte Carlo scheme with Langevin dynamics. Our interest is mainly motivated by the question: what is the parameter space in which simulations may be performed with reliable results and how does the average sign scales with inverse temperature? In the parameter space in which one may omit the sign problem we have studied the ground state properties: momentum distribution and spin structure. We find an exponential decay of the average sign. At half filling, we find evidence for an antiferromagnetic insulating ground state. At off half band fillings, the antiferromagnetic state is destroyed leaving place to an incommensurate spin density state. 相似文献
7.
Kai Diethelm 《PAMM》2016,16(1):837-838
Score-P is a measurement infrastructure originally designed for the analysis and optimization of the performance of HPC codes. Recent extensions of Score-P and its associated tools now also allow the investigation of energy-related properties and support the user in the implementation of corresponding improvements. Since it would be counterproductive to completely ignore performance issues in this connection, the focus should not be laid exclusively on energy. We therefore aim to optimize software with respect to an objective function that takes into account energy and run time. (© 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
8.
Christian G. Haselberger Diethelm J. Gauster Helmut Schenkel-Brunner 《Monatshefte für Chemie / Chemical Monthly》1983,114(5):625-630
Due to their easy purification nitrophenyl-glycosides have become of increasing interest as acceptor substrates for the assay of glycosyltransferase activity. In this communication reversed-phase chromatography is shown to provide a convenient means for the isolation of the radioactively labelled nitrophenylglycoside(s) formed in this reaction, superior to the methods hitherto used with regard to speed and specifity. 相似文献
9.
A. F. Joseph F. P. Treadwell W. T. Hall F. Sutton L. L. de Koninck J. M. Kolthoff F. W. Küster Fr. L. Hahn H. Windisch W. Böttger C. Russo A. Monnier O. Hackl W. M. Thornton jr. J. E. Chapman L. Brandt E. Knecht Eva Hibbert O. Tomiček E. Polidori B. Diethelm F. Foerster W. M. Thornton L. Moser W. A. Hicks K. Schröder 《Analytical and bioanalytical chemistry》1926,68(9-10):369-384
10.
S. Diethelm D. Bayraktar T. Graule P. Holtappels J. Van herle 《Solid State Ionics》2009,180(11-13):857-860
(La,Sr)FeO3 mixed conducting perovskites are considered as interesting candidates for oxygen separation membranes but they suffer from limited structural stability in a large oxygen partial pressure (pO2) gradient, because of their propensity for chemical expansion. Partial substitution of Fe with more stable elements tends to improve the stability while penalizing the electronic and ionic conductivities.In this study, we investigate the effect of 10% Ta substitution on the oxygen transport properties and stability of La0.5Sr0.5FeO3. For this purpose, the material was evaluated as a membrane in a CPOX reactor. The oxygen permeation through a ~ 3 cm2 pellet sample was first measured under air/Ar gradient in the temperature range of 800 to 1000 °C. The measured flux was 0.1 µmol cm? 2 s? 1 at 900 °C, which was a factor of 2 lower than for the Ta-free material. Methane was then introduced into the system and reacted in a catalytic bed with oxygen that has permeated through the membrane to form syngas (H2, CO). As a result, the oxygen flux increased by a factor of 9, reaching 0.9 µmol cm? 2 s? 1 at 900 °C. The reactor was operated at 1000 °C for another 1000 h. During this time, the oxygen permeation flux decayed by ca. 4%/1000 h.The test was stopped after more than 2000 h of operation and the membrane analyzed by electron microscopy. 相似文献