全文获取类型
收费全文 | 78篇 |
免费 | 4篇 |
国内免费 | 2篇 |
专业分类
化学 | 50篇 |
晶体学 | 2篇 |
力学 | 1篇 |
数学 | 5篇 |
物理学 | 26篇 |
出版年
2019年 | 1篇 |
2017年 | 2篇 |
2016年 | 3篇 |
2015年 | 1篇 |
2014年 | 3篇 |
2013年 | 7篇 |
2012年 | 5篇 |
2011年 | 8篇 |
2010年 | 7篇 |
2009年 | 5篇 |
2008年 | 3篇 |
2007年 | 4篇 |
2006年 | 4篇 |
2005年 | 2篇 |
2004年 | 1篇 |
2003年 | 2篇 |
2000年 | 1篇 |
1999年 | 1篇 |
1996年 | 2篇 |
1995年 | 1篇 |
1994年 | 1篇 |
1992年 | 4篇 |
1988年 | 1篇 |
1985年 | 1篇 |
1984年 | 2篇 |
1982年 | 1篇 |
1980年 | 1篇 |
1978年 | 1篇 |
1977年 | 1篇 |
1976年 | 1篇 |
1975年 | 1篇 |
1973年 | 2篇 |
1970年 | 2篇 |
1887年 | 2篇 |
排序方式: 共有84条查询结果,搜索用时 31 毫秒
1.
Binyuan Liu Yang Li Boo‐Gyo Shin Do Yeung Yoon IL Kim Li Zhang Weidong Yan 《Journal of polymer science. Part A, Polymer chemistry》2007,45(15):3391-3399
Three novel functionalized polynorbornenes (PNB) with pendant dimethyl carboxylate group (carboxylates—acetate, propionate, and butyrate) are synthesized as a vinyl‐type with a palladium (II) catalyst in high yield. The effects of size of substitutents, molar ratio of monomer to catalyst, solvent polarity, reaction time, and temperature on the polymerization of exo‐norbornene dimethyl propionate were systematically investigated. The low molar ratio and temperature, as well as high polarity of solvent, and long reaction time, are favorable for the enhancement of the monomer conversion, especially, the solvent have an obvious effect on the catalyst activity. The resulting poly(cis‐norbornene‐exo‐2,3‐dimethyl carboxylates) (PNB‐dimethyl carboxylates) show good solubility in common organic solvent and high thermal stability up to 360 °C. The glass transition temperature was detected by DMA at 331, 324, and 318 °C for acetate, propionate, and butyrate, respectively. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 3391–3399, 2007 相似文献
2.
On Phase Diagrams of Rare Earth Trichlorides/MCl2 (Rare Earth = La, Sm, Gd, yb; M = Sr, Ba) The systems LaCl3(SmCl3, GdCl3, YbCl3)? SrCl2(BaCl2) were determined by difference thermal analysis. The phase diagrams contain compounds of the formula BaLnCl5, M2LnCl7, Ba3LnCl9 and probably Sr4LnCl11, which decompose peritectoidally resp. peritectically. Sr2SmCl7 and Sr2GdCl7 are isotypic, and as indicated by the very similar reflection patterns of the Guinier photographs related to the structure of the compound Sm3Cl7. The phase diagrams are comparable to the systems LnCl3? LnCl2 with similar radii quotients of the cations. The enthalpies of mixing of the systems LaCl3(GdCl3, YbCl3)? SrCl2 were measured calorimetrically. The values are exothermic, the minima were found at approximately 65 mol-% SrCl2. 相似文献
3.
Cyclic Malonoyl peroxides, first reported in 1971 (1) are an important class of compounds for the study of α-lactones (2). These peroxides were prepared by treating a substituted malonic acid with 98% hydrogen peroxide in methanesulfonic acid. A serious disadvantage of this method is the use and the storage of concentrated hydrogen peroxide as well as the remote control device recommended (3) for the operation of this explosive reagent. 相似文献
4.
MODELING HARVEST SCHEDULING IN MULTIFUNCTIONAL PLANNING OF FORESTS FOR LONGTERM WATER YIELD OPTIMIZATION 下载免费PDF全文
HAYATI ZENGIN ÜNAL ASAN SINAN DESTAN MURAT ENGIN ÜNAL AHMET YEŞIL PETE BETTINGER AHMET SALIH DEĞERMENCI 《Natural Resource Modeling》2015,28(1):59-85
In this study, wood production and hydrologic functions of forests were accommodated within a planning procedure for separate working circles (areas dedicated to certain forest functions) that were delineated according to an Ecosystem‐Based Functional Planning approach. Mixed integer goal programming was used as the optimization technique. The timing and scheduling of a maintenance cutting (partial harvest) was the decision variable in the modeling effort, and an original formulation was developed as a multiobjective planning procedure. Four sample planning strategies were developed and model outputs were evaluated according to these strategies. Spatial characteristics of stands were considered, and used to prohibit the regeneration of adjacent stands during the same time period. Because of the positive relationship between qualified water production and standing timber volume in the forest, the model attempts to maximize qualified water production levels by increasing standing volume stocks in the forest through the delay of regeneration activities. 相似文献
5.
6.
Fullerton EE Robertson JL Prinsloo AR Alberts HL Bader SD 《Physical review letters》2003,91(23):237201
We have measured the antiferromagnetic spin-density-wave (SDW) order in Cr/Cr(97.5)Mn2.5(001) superlattices. The Mn doping creates a high Néel temperature layer that confines the incommensurate SDW order within the Cr layers. With temperature cycling we observe a transition from commensurate to incommensurate SDW order and discrete changes in the SDW period. We find that these transitions show significant hysteresis (up to 75 K) when the number of SDW nodes within the Cr layer changes by an odd number, while there is no hysteresis for changes of an even number of nodes. This results from the competition between maintaining the spin structure at the interfaces and introducing a spin slip at the nodes of the Cr SDW. 相似文献
7.
8.
Tom Alberts Jeremy Clark Saša Kocić 《Stochastic Processes and their Applications》2017,127(10):3291-3330
We study a directed polymer model defined on a hierarchical diamond lattice, where the lattice is constructed recursively through a recipe depending on a branching number and a segment number . When it is known that the model exhibits strong disorder for all positive values of the inverse temperature , and thus weak disorder reigns only for (infinite temperature). Our focus is on the so-called intermediate disorder regime in which the inverse temperature vanishes at an appropriate rate as the size of the system grows. Our analysis requires separate treatment for the cases and . In the case we prove that when the inverse temperature is taken to be of the form for , the normalized partition function of the system converges weakly as to a distribution and does so universally with respect to the initial weight distribution. We prove the convergence using renormalization group type ideas rather than the standard Wiener chaos analysis. In the case we find a critical point in the behavior of the model when the inverse temperature is scaled as ; for an explicitly computable critical value the variance of the normalized partition function converges to zero with large when and grows without bound when . Finally, we prove a central limit theorem for the normalized partition function when . 相似文献
9.
10.
A. A. Lamberov I. F. Khalilov I. R. IL’yasov A. Sh. Bikmurzin V. M. Shatilov I. F. Nazmieva 《Russian Journal of Applied Chemistry》2011,84(8):1385-1393
Effect of modification with an alkali metal on the acid properties of alumina supports and on the oligomerization capacity
and working stability of Pd-Al2O3 catalysts was studied. 相似文献