全文获取类型
收费全文 | 115篇 |
免费 | 5篇 |
专业分类
化学 | 93篇 |
晶体学 | 3篇 |
力学 | 4篇 |
数学 | 5篇 |
物理学 | 15篇 |
出版年
2022年 | 5篇 |
2017年 | 1篇 |
2016年 | 4篇 |
2015年 | 1篇 |
2014年 | 2篇 |
2013年 | 6篇 |
2012年 | 2篇 |
2011年 | 2篇 |
2010年 | 2篇 |
2009年 | 3篇 |
2008年 | 7篇 |
2007年 | 1篇 |
2006年 | 7篇 |
2005年 | 1篇 |
2004年 | 4篇 |
2003年 | 3篇 |
2002年 | 4篇 |
2001年 | 6篇 |
1999年 | 3篇 |
1998年 | 1篇 |
1997年 | 1篇 |
1994年 | 2篇 |
1992年 | 3篇 |
1991年 | 2篇 |
1990年 | 4篇 |
1988年 | 1篇 |
1987年 | 1篇 |
1986年 | 5篇 |
1985年 | 5篇 |
1984年 | 1篇 |
1982年 | 1篇 |
1981年 | 2篇 |
1980年 | 2篇 |
1979年 | 2篇 |
1978年 | 3篇 |
1977年 | 1篇 |
1976年 | 1篇 |
1975年 | 1篇 |
1974年 | 7篇 |
1973年 | 5篇 |
1968年 | 1篇 |
1939年 | 1篇 |
1936年 | 2篇 |
1932年 | 1篇 |
排序方式: 共有120条查询结果,搜索用时 218 毫秒
61.
Chao Chen Florian Eweiner Birgit Wibbeling Roland Frhlich Shunsuke Senda Yasuhiro Ohki Kazuyuki Tatsumi Stefan Grimme Gerald Kehr Gerhard Erker 《化学:亚洲杂志》2010,5(10):2199-2208
The zirconocene complex [{(C6F5)2B‐(CH2)3‐Cp}(Cp‐PtBu2)ZrCl2] ( 6 ; Cp=cyclo‐C5H4) was prepared by hydroboration of [(allyl‐Cp)(Cp‐PtBu2)ZrCl2] ( 5 ) with HB(C6F5)2 (“Piers’ borane”). It represents a frustrated Lewis pair (FLP) in which both the Lewis acid and the Lewis base were attached at the metallocene framework. Its reaction with 1‐pentyne did not result in the 1,2‐addition of or deprotonation reaction by the FLP, but rather in the 1,1‐carboboration of the triple bond, thereby obtaining a Z/E mixture (1.2:1) of the respective organometallic substituted alkenes 7 . The analogous reaction of 1‐pentyne with the phosphorous‐free system [{(C6F5)2B‐(CH2)3‐Cp)}CpZrCl2] ( 9 ) gave the respective 1,1‐carboboration products ( Z‐10 / E‐10 ≈1.3:1). 相似文献
62.
63.
A simple dipeptide, (S)-phenylglycyl-(R)-phenylglycine (S,R-1), formed inclusion compounds with a small amide such as formamide, acetamide, N,N-dimethylformamide (DMF), or N,N-dimethylacetamide. By single-crystal X-ray analysis, the inclusion compounds were shown to have a wavy layer structure. The molecules of S,R-1 are arranged in parallel via ionic pairing of the carboxyl and amino groups to construct the wavy layers. The guest molecules were accommodated in a channel cavity between the layers by means of hydrogen bonding with (+)NH(3) of S,R-1. The cavity is surrounded by the phenyl groups of S,R-1 that conformationally rotate so as to make the cavity size fit the guest amide. 相似文献
64.
Akihide Kaizawa Nobuhiro Maruoka Atsushi Kawai Hiroomi Kamano Tetsuji Jozuka Takeshi Senda Tomohiro Akiyama 《Heat and Mass Transfer》2008,44(7):763-769
A waste heat transportation system––trans-heat (TH) system––is quite attractive that uses the latent heat of a phase change
material (PCM). The purpose of this paper is to study the thermophysical properties of various sugars and sodium acetate trihydrate
(SAT) as PCMs for a practical TH system and the heat transfer property between PCM selected and heat transfer oil, by using
differential scanning calorimetry (DSC), thermogravimetry-differential thermal analysis (TG-DTA) and a heat storage tube.
As a result, erythritol, with a large latent heat of 344 kJ/kg at melting point of 117°C, high decomposition point of 160°C
and excellent chemical stability under repeated phase change cycles was found to be the best PCM among them for the practical
TH system. In the heat release experiments between liquid erythritol and flowing cold oil, we observed foaming phenomena of
encapsulated oil, in which oil droplet was coated by solidification of PCM. 相似文献
65.
Tomoaki Kawaguchi Koji Tagawa Fumiyo Senda Takayuki Matsunaga Hiromi Kitano 《Journal of colloid and interface science》1999,210(2):290
Amphiphiles which carry many pendent galactose residues as side chains were prepared by telomerization of 2-methacryloyloxyethyl β-D-galactopyranoside (MEGal) or 3-(2-methacryloyl aminoethylthio)propylD-galactopyranoside (MEPGal, α:β = 3.9:1) using a lipophilic radical initiator. The galactose-carrying amphiphiles (DP (degree of polymerization) = 15) incorporated in liposomes were recognized by a lectin fromRicinus communis(RCA120), which was proven by the increase in turbidity of the liposome suspension after mixing with the lectin. The recognition was largely affected by the distance between the galactose residues and the polymer main chain, and the surface density of the amphiphile in the liposomes. The liposomes containing these galactolipids were not taken up by mouse peritoneal macrophages, probably due to a steric hindrance of polymer main chains from the uptake of D-galactose receptors on the macrophages. 相似文献
66.
Satomi Yokota Akitsugu Sasaki Yoshio Hotta Yuji Yamane Hideaki Kimura Shigeki Kuroki Isao Ando 《Macromolecular Symposia》2004,207(1):105-110
1H-chemical shift NMR imaging patterns of a poly(methacrylic acid) gel containing water with paramagnetic praseodymium ions(Pr3+) were successfully observed, in order to elucidate spatial distribution of Pr3+ ions in the gel. The 1H chemical shift of water associated with Pr3+ ions in the gel moves largely downfield. By analyzing these experimental results, the immersion process of Pr3+ ions into the network of the polymer gel was spatially clarified. Further, it is shown that the chemical shift NMR imaging method is a useful means for determining the spatial distribution of paramagnetic metal ions in polymer gels. 相似文献
67.
The entropy generation analysis of adiabatic combustion systems was performed to quantify the exergy losses which are mainly the exergy destroyed during combustion inside the chamber and in the exhaust gases. The purpose of the present work was therefore: (a) to extend the exergy destruction analysis by including the exhaust gas exergy while applying the hybrid filtered Eulerian stochastic field (ESF) method coupled with the FGM chemistry tabulation strategy; (b) to introduce a novel method for evaluating the exergy content of exhaust gases; and (c) to highlight a link between exhaust gas exergy and combustion emissions. In this work, the adiabatic Sandia flames E and F were chosen as application combustion systems. First, the numerical results of the flow and scalar fields were validated by comparison with the experimental data. The under-utilization of eight stochastic fields (SFs), the flow field results and the associated scalar fields for the flame E show excellent agreement contrary to flame F. Then, the different exergy losses were calculated and analyzed. The heat transfer and chemical reaction are the main factors responsible for the exergy destruction during combustion. The chemical exergy of the exhaust gases shows a strong relation between the exergy losses and combustion emission as well as the gas exhaust temperature. 相似文献
68.
The hydrolysis-precipitation equilibrium reaction of aqueous gallium(III) solution was investigated in 0–3 mol-kg-1 NaCl media at low pH at 100°C using a pressure-tight glass vessel. All precipitates were identified as GaOOH. The results
were analyzed with a nonlinear least-squares computer program to obtain the solubility product Kso for gallium(III) oxyhydroxide using a single-parameter type of Debye-Hückel equation. The value of log Kso for GaOOH(s) + 3H+ ⇆ Ga3+ + 2H2O was -0.60 at 100°C. The solubility product calculated from thermodynamic data was compared with the experimental result. 相似文献
69.
Yoshizo Fukuyama Mari Senda Takahiko Kawai Shin-ichi Kuroda Masahito Toyonaga Toshiaki Taniike Minoru Terano 《Journal of Thermal Analysis and Calorimetry》2014,117(3):1397-1405
The thermal conductivity of Isotactic polypropylene (iPP)/silica particle (SiO2, 26 nm) nanocomposite has been investigated. The untreated SiO2 and iPP grafted onto SiO2 were dispersed in the iPP (M w = 2.5 × 105) matrix. The molecular mass of the iPP-grafted chain, M n, was precisely controlled to be 5.8 × 103, 1.2 × 104, and 4.6 × 104. It was found that the thermal conductivities of graft-treated nanocomposites were higher than that of untreated SiO2 composites. This implied that it is possible to achieve even higher thermal conductivity using the graft treatment. A thermal conductivity analysis conducted using a three-phase model, with considerations for thermal conductivity at interfacial layers, showed that the thermal conductivity of the interfacial layer increased significantly when a graft chain was incorporated. Moreover, the thermal conductivity per graft chain was proportional to the 1/2 power of the molecular mass ( \( M_{\text{n}}^{0.5} \) ). The results strongly suggest that the thermal conductivity pathway of interfacial layer was the main chain direction of iPP-grafted molecular chains. 相似文献
70.
Cooperative Catalysis: Enantioselective Propargylic Alkylation of Propargylic Alcohols with Enecarbamates Using Ruthenium/Phosphoramide Hybrid Catalysts
下载免费PDF全文
![点击此处可从《Angewandte Chemie (International ed. in English)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Yasushi Senda Dr. Kazunari Nakajima Prof. Dr. Yoshiaki Nishibayashi 《Angewandte Chemie (International ed. in English)》2015,54(13):4060-4064
The diastereo‐ and enantioselective propargylic alkylation of propargylic alcohols with E‐enecarbamates in the presence of a catalytic amount of thiolate‐bridged diruthenium complexes bearing an optically active phosphoramide moiety gives the corresponding propargylic alkylated products (up to 97 % ee). 相似文献