全文获取类型
收费全文 | 173篇 |
免费 | 5篇 |
专业分类
化学 | 53篇 |
力学 | 6篇 |
数学 | 60篇 |
物理学 | 59篇 |
出版年
2022年 | 3篇 |
2020年 | 1篇 |
2019年 | 1篇 |
2017年 | 2篇 |
2016年 | 6篇 |
2015年 | 8篇 |
2014年 | 1篇 |
2012年 | 8篇 |
2011年 | 14篇 |
2010年 | 13篇 |
2009年 | 13篇 |
2008年 | 10篇 |
2007年 | 8篇 |
2006年 | 10篇 |
2005年 | 8篇 |
2004年 | 3篇 |
2003年 | 4篇 |
2002年 | 6篇 |
2001年 | 4篇 |
2000年 | 1篇 |
1998年 | 1篇 |
1997年 | 2篇 |
1996年 | 1篇 |
1995年 | 1篇 |
1993年 | 2篇 |
1989年 | 3篇 |
1988年 | 2篇 |
1986年 | 3篇 |
1983年 | 1篇 |
1975年 | 2篇 |
1971年 | 1篇 |
1968年 | 2篇 |
1967年 | 1篇 |
1966年 | 1篇 |
1958年 | 1篇 |
1957年 | 1篇 |
1956年 | 1篇 |
1955年 | 1篇 |
1944年 | 1篇 |
1942年 | 1篇 |
1935年 | 4篇 |
1934年 | 3篇 |
1933年 | 3篇 |
1932年 | 4篇 |
1931年 | 1篇 |
1930年 | 2篇 |
1929年 | 3篇 |
1926年 | 1篇 |
1905年 | 2篇 |
1888年 | 1篇 |
排序方式: 共有178条查询结果,搜索用时 62 毫秒
1.
Mechanistic Aspects of a Highly Active Dinuclear Zinc Catalyst for the Co‐polymerization of Epoxides and CO2
下载免费PDF全文
![点击此处可从《Chemistry (Weinheim an der Bergstrasse, Germany)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Stefan Kissling Peter T. Altenbuchner Dr. Maximilian W. Lehenmeier Dr. Eberhardt Herdtweck Dr. Peter Deglmann Dr. Uwe B. Seemann Prof. Dr. Bernhard Rieger 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(22):8148-8157
The dinuclear zinc complex reported by us is to date the most active zinc catalyst for the co‐polymerization of cyclohexene oxide (CHO) and carbon dioxide. However, co‐polymerization experiments with propylene oxide (PO) and CO2 revealed surprisingly low conversions. Within this work, we focused on clarification of this behavior through experimental results and quantum chemical studies. The combination of both results indicated the formation of an energetically highly stable intermediate in the presence of propylene oxide and carbon dioxide. A similar species in the case of cyclohexene oxide/CO2 co‐polymerization was not stable enough to deactivate the catalyst due to steric repulsion. 相似文献
2.
R. E. Ansorge B. ?sman C. N. Booth L. Burow P. Carlson R. S. De Wolf B. Eckart G. Ekspong C. Fuglesang J. Gaudaen C. Geich-Gimbel B. Holl R. Hospes K. Jon-And D. P. Johnson F. Lotse N. Manthos D. J. Munday J. E. V. Ovens W. Pelzer J. G. Rushbrooke F. Triantis L. Van hamme C. Walck C. P. Ward D. R. Ward C. J. S. Webber T. O. White G. Wilquet N. Yamdagni UA Collaboration 《Zeitschrift fur Physik C Particles and Fields》1988,41(2):179-190
A detailed analysis ofK s 0 production in \(\bar pp\) |<2.5 the average transverse momentum is found to be 0.53±0.07 GeV/c at 200 GeV and 0.62±0.08 GeV/c at 900 GeV, which is an increase with respect to data at c.m. energies below 60 GeV. TheK s 0 production cross sections in inelastic collisions are 29±4 mb at 200 GeV and 63±6 mb at 900 GeV, showing an increase compared to lower energy data. The central kaon density is found to increase as a logarithmic function of energy. At 900 GeV, where statistics are sufficient to allow one to draw conclusions, the average transverse momentum is higher in events with large charged multiplicity than in events with low multiplicity. 相似文献
3.
The reactivity of hydroxy-indoles under the conditions of the Mannich-reaction has been studied. The electrophilic side-chain enters in each case in a position ortho to the phenolic group. 4-Hydroxy-indole is substituted in the 5-, 5-hydroxy-indole in the 4-, 6-hydroxy-indole in the 7-, and 7-hydroxy-indole probably in the 6-position. The structures of the Mannich bases from 4-, 5- and 6-hydroxy-indole have been confirmed by comparison of the hydroxy-methyl-indoles obtained by reductive desamination with hydroxy-methyl-indoles prepared by unambiguous total synthesis. 相似文献
4.
Formation constants are reported for the levulinate complexes of manganese(II), cobalt(II), nickel(II), copper(II) and zinc(II) at 25 degrees in 0.1M chloride medium. In addition, results are presented for the corresponding acetate complexes for comparison. Protonation constants for the two ligands are also reported. 相似文献
5.
6.
Ralf Seemann Jean-Baptiste Fleury Corinna C. Maass 《The European physical journal. Special topics》2016,225(11-12):2227-2240
Self-propelled droplets are a special kind of self-propelled matter that are easily fabricated by standard microfluidic tools and locomote for a certain time without external sources of energy. The typical driving mechanism is a Marangoni flow due to gradients in the interfacial energy on the droplet interface. In this article we review the hydrodynamic prerequisites for self-sustained locomotion and present two examples to realize those conditions for emulsion droplets, i.e. droplets stabilized by a surfactant layer in a surrounding immiscible liquid. One possibility to achieve self-propelled motion relies on chemical reactions affecting the surface active properties of the surfactant molecules. The other relies on micellar solubilization of the droplet phase into the surrounding liquid phase. Remarkable cruising ranges can be achieved in both cases and the relative insensitivity to their own ‘exhausts’ allows to additionally study collective phenomena. 相似文献
7.
8.
Herminghaus S. Jacobs K. Seemann R. 《The European physical journal. E, Soft matter》2001,5(1):531-538
The European Physical Journal E - A simple and predictive model is put forward explaining the experimentally observed substantial shift of the glass transition temperature, T g, of sufficiently... 相似文献
9.
R. E. Ansorge B. ?sman L. Burow P. Carlson R. S. DeWolf B. Eckart G. Ekspong I. Evangelou C. Fuglesang J. Gaudaen C. Geich-Gimbel B. Holl K. Jon-And F. Lotse N. Manthos D. J. Munday W. Pelzer J. G. Rushbrooke F. Triantis L. Van Hamme C. Walck C. P. Ward D. R. Ward C. J. S. Webber T. O. White G. Wilquet N. Yamdagni UA Collaboration 《Zeitschrift fur Physik C Particles and Fields》1989,43(3):357-374
Multiplicity distributions of charged particles produced in non single-diffractive collisions between protons and antiprotons at centre of mass energies of 200 and 900 GeV are presented. The data were recorded in the UA5 streamer chambers at the CERN Collider, which was operated in a pulsed mode between the two energies. A new method to correct for acceptance limitations and inefficiencies based on the principle of maximum entropy has been used. Multiplicity distributions in full phase space and in intervals of pseudorapidity are presented in tabular form. The violation of KNO scaling in full phase space found by the UA5 group at an energy of 546 GeV is confirmed also at 200 and 900 GeV. The shape of the 900 GeV distribution in full phase space is narrower in the peak region than at 200 GeV but exhibits a pronounced high multiplicity tail. The negative binomial distribution fits data at 200 GeV in all pseudorapidity intervals and in small intervals at 900 GeV. In large intervals at 900 GeV, however, the negative binomial distribution. Fits to the partially coherent laser distribution are also presented as well as comparisons with predictions of the Dual Parton, the Fritiof and the Pythia models. 相似文献
10.
G. Steinhauser W. Hujer J. H. Sterba R. Seemann M. Bichler N. Symeonidis 《Journal of Radioanalytical and Nuclear Chemistry》2008,276(1):167-173
The sediments of Charkadio Cave (Island of Tilos) have been object of chemical and mineralogical investigation. Sampling the
speleothems of Charkadio Cave, it is possible to look back into the island’s younger geological history. Tilos is of non-volcanic
origin but neighbored to several volcanoes of the Aegean (Kos, Nisyros, and Giali). We observed a certain coincidence of increased
Ba and Sr values in such samples and volcanic activity. Some of the layers of these fine-grained sediments contain volcanic
particles (ash grains and lapilli). Interestingly, these strata have the highest content of Ba and Sr, as determined by neutron
activation analysis. Additionally to this discovery, Sr-rich barite crystals were found in some of these layers. Thus, Ba
and Sr must either exist on the surface of tephra particles in volatile and water-soluble compounds and/or were released by
weathering from Ba and Sr containing feldspars (originating from pumice) in the cave sediment environment. Since other cave
sediments from Tilos, which were not exposed to volcanic products, contain very much lesser quantities of Ba and Sr, we conclude
that mobile Ba and Sr compounds are contributed to the sediment by volcanic fallout. 相似文献