全文获取类型
收费全文 | 146篇 |
免费 | 2篇 |
国内免费 | 7篇 |
专业分类
化学 | 95篇 |
晶体学 | 1篇 |
力学 | 1篇 |
数学 | 19篇 |
物理学 | 39篇 |
出版年
2021年 | 2篇 |
2020年 | 3篇 |
2019年 | 4篇 |
2018年 | 2篇 |
2017年 | 3篇 |
2013年 | 2篇 |
2012年 | 7篇 |
2011年 | 5篇 |
2010年 | 5篇 |
2009年 | 3篇 |
2008年 | 9篇 |
2007年 | 9篇 |
2006年 | 7篇 |
2005年 | 2篇 |
2004年 | 3篇 |
2003年 | 8篇 |
2002年 | 5篇 |
2001年 | 6篇 |
2000年 | 3篇 |
1999年 | 3篇 |
1997年 | 6篇 |
1996年 | 4篇 |
1995年 | 4篇 |
1994年 | 1篇 |
1993年 | 1篇 |
1992年 | 2篇 |
1991年 | 2篇 |
1990年 | 2篇 |
1988年 | 1篇 |
1986年 | 2篇 |
1985年 | 3篇 |
1984年 | 2篇 |
1981年 | 1篇 |
1979年 | 2篇 |
1978年 | 2篇 |
1975年 | 1篇 |
1973年 | 7篇 |
1972年 | 1篇 |
1970年 | 2篇 |
1966年 | 1篇 |
1965年 | 2篇 |
1964年 | 1篇 |
1963年 | 2篇 |
1962年 | 2篇 |
1960年 | 1篇 |
1957年 | 1篇 |
1933年 | 1篇 |
1908年 | 1篇 |
1905年 | 2篇 |
1899年 | 1篇 |
排序方式: 共有155条查询结果,搜索用时 15 毫秒
101.
The relative rates of H-transfer between partners in ion-neutral complexes were compared with those in intramolecular rearrangements using results of first differential photoionization mass spectrometry measurements. Complex-mediated H-transfers are inferred to have rates of the same order as those for intramolecular hydrogen rearrangements, suggesting a similar range of motion of the reactive sites in both types of reactions. It is also concluded that at their fastest H-transfers take place between the partners in ion-neutral complexes within at most the time of several rotations of the partners in the complexes. Copyright 1999 John Wiley & Sons, Ltd. 相似文献
102.
103.
A model based on one-dimensional electron gas theory has been developed which improves the π-electron wave functions of conjugated molecules by taking changes of bond length differences into account. Experimental bond lengths are reproduced with an average deviation of 0·005 Å; excitation energies are markedly improved over the simple model. The reliability of the model with respect to geometries is comparable to the PPP-SCF method. 相似文献
104.
105.
Buss F Roberts CC Crawford KS Peters K Francis LF 《Journal of colloid and interface science》2011,359(1):112-120
Soluble polymer is frequently added to inorganic particle suspensions to provide mechanical strength and adhesiveness to particulate coatings. To engineer coating microstructure, it is essential to understand how drying conditions and dispersion composition influence particle and polymer distribution in a drying coating. Here, a 1D model revealing the transient concentration profiles of particles and soluble polymer in a drying suspension is proposed. Sedimentation, evaporation and diffusion govern particle movement with the presence of soluble polymer influencing the evaporation rate and solution viscosity. Results are summarized in drying regime maps that predict particle accumulation at the free surface or near the substrate as conditions vary. Calculations and experiments based on a model system of poly(vinyl alcohol) (PVA), silica particles and water reveal that the addition of PVA slows the sedimentation and diffusion of the particles during drying such that accumulation of particles at the free surface is more likely. 相似文献
106.
Anna M. Wagner Claire E. Knezevic Jessica L. Wall Victoria L. Sun Joshua A. Buss LeeAnn T. Allen Anna G. Wenzel 《Tetrahedron letters》2012,53(7):833-836
A copper(II)-catalyzed, sequential Michael addition-aldol condensation reaction of N-carboxybenzyl-protected aminobenzaldehyde with various α,β-unsaturated N-acyl pyrroles is described. Substrate scope was found to include both aryl and aliphatic N-acyl pyrroles as the Michael acceptors, and isolated product yields as high as 93% were observed. The use of acetonitrile as the reaction solvent proved to be crucial for catalysis, both to function as a labile ligand for copper, as well as an agent to minimize hydrolytic catalyst poisoning. 相似文献
107.
Wilkinson B Foster G Rudd BA Taylor NL Blackaby AP Sidebottom PJ Cooper DJ Dawson MJ Buss AD Gaisser S Böhm IU Rowe CJ Cortés J Leadlay PF Staunton J 《Chemistry & biology》2000,7(2):111-117
BACKGROUND: The macrolide antibiotic erythromycin A, like other complex aliphatic polyketides, is synthesised by a bacterial modular polyketide synthase (PKS). Such PKSs, in contrast to other fatty acid and polyketide synthases which work iteratively, contain a separate set or module of enzyme activities for each successive cycle of polyketide chain extension, and the number and type of modules together determine the structure of the polyketide product. Thus, the six extension modules of the erythromycin PKS (DEBS) together catalyse the production of the specific heptaketide 6-deoxyerythronolide B. RESULTS: A mutant strain of the erythromycin producer Saccharopolyspora erythraea, which accumulates the aglycone intermediate erythronolide B, was found unexpectedly to produce two novel octaketides, both 16-membered macrolides. These compounds were detectable in fermentation broths of wild-type S. erythraea, but not in a strain from which the DEBS genes had been specifically deleted. From their structures, both of these octaketides appear to be aberrant products of DEBS in which module 4 has 'stuttered', that is, has catalysed two successive cycles of chain extension. CONCLUSIONS: The isolation of novel DEBS-derived octaketides provides the first evidence that an extension module in a modular PKS has the potential to catalyse iterative rounds of chain elongation like other type I FAS and PKS systems. The factors governing the extent of such 'stuttering' remain to be determined. 相似文献
108.
Andreas?B?SchmittEmail author Sebastian?Breuer Jan?Liman Armin?Buss Christiane?Schlangen Katrin?Pech Elly?M?Hol Gary?A?Brook Johannes?Noth Franz-Werner?Schwaiger 《BMC neuroscience》2003,4(1):8
Background
It is well known that neurons of the peripheral nervous system have the capacity to regenerate a severed axon leading to functional recovery, whereas neurons of the central nervous system do not regenerate successfully after injury. The underlying molecular programs initiated by axotomized peripheral and central nervous system neurons are not yet fully understood. 相似文献109.
110.
H. Buss und H. W. Kohlschütter 《Fresenius' Journal of Analytical Chemistry》1962,186(1):193-194
Ohne ZusammenfassungEine ausführliche Veröffentlichung erfolgt demnächst in dieser Zeitschrift. 相似文献