全文获取类型
收费全文 | 171篇 |
免费 | 15篇 |
国内免费 | 16篇 |
专业分类
化学 | 148篇 |
晶体学 | 1篇 |
力学 | 4篇 |
数学 | 15篇 |
物理学 | 34篇 |
出版年
2024年 | 1篇 |
2022年 | 4篇 |
2021年 | 3篇 |
2020年 | 7篇 |
2019年 | 6篇 |
2018年 | 8篇 |
2017年 | 7篇 |
2016年 | 9篇 |
2015年 | 10篇 |
2014年 | 13篇 |
2013年 | 10篇 |
2012年 | 14篇 |
2011年 | 9篇 |
2010年 | 3篇 |
2009年 | 3篇 |
2008年 | 13篇 |
2007年 | 9篇 |
2006年 | 12篇 |
2005年 | 10篇 |
2004年 | 13篇 |
2003年 | 4篇 |
2002年 | 3篇 |
2001年 | 2篇 |
2000年 | 3篇 |
1999年 | 2篇 |
1998年 | 3篇 |
1995年 | 3篇 |
1993年 | 1篇 |
1991年 | 1篇 |
1990年 | 2篇 |
1989年 | 2篇 |
1987年 | 3篇 |
1986年 | 2篇 |
1985年 | 1篇 |
1982年 | 1篇 |
1981年 | 2篇 |
1975年 | 1篇 |
1964年 | 2篇 |
排序方式: 共有202条查询结果,搜索用时 15 毫秒
141.
Li Z Liu Z Zhang J Han B Du J Gao Y Jiang T 《The journal of physical chemistry. B》2005,109(30):14445-14448
Large-size single-crystal gold nanosheets have been successfully prepared by microwave heating of HAuCl(4) in ionic liquid, 1-butyl-3-methylimidazolium tetrafluoroborate, without any additional template agent. Transmission electron microscopy (TEM), electron diffraction (ED), scanning electron microscopy (SEM), and X-ray powder diffraction (XRD) were used to characterize the resultant gold nanosheets. It was demonstrated that the ionic liquid could act as template agent for the formation of gold nanosheets. The present synthesis route is very simple and fast. It can be expected that the method can be extended to the fabrication of other metal nanosheets in ionic liquids. 相似文献
142.
Tiancheng Mu Zhonghao Li Jianling Zhang Xiaogang Zhang 《The Journal of chemical thermodynamics》2003,35(12):2033-2044
The phase behavior, density, and constant-volume molar heat capacity (Cv,m) of ethane + n-pentane binary mixtures have been measured in the supercritical region and subcritical region at T=309.45 K. In addition, the isothermal compressibility (κT) has been calculated using the density data determined. For a mixed fluid with a composition close to the critical composition, Cv,m and κT increase sharply as the pressure approaches the critical point (CP), the dew point (DP), or the bubble point (BP). However, Cv,m is not sensitive to pressure in the entire pressure range if the composition of the mixed fluid is far from the critical composition. To tune the properties of the binary mixtures effectively by pressure, both the composition and the pressure should be close to the critical point of the mixture. The intermolecular interactions in the mixture are also discussed on the basis of the experimental results. 相似文献
143.
杯芳烃固定液分子识别的热力学性质 总被引:3,自引:0,他引:3
用毛细管气相色谱法测得了5组芳香族位置异构体在杯芳冠醚聚硅氧烷(C[4]C5_PSO),二乙氧基杯芳烃聚硅氧烷(C[4]E_PSO)和二丁氧基杯芳烃聚硅氧烷(M_C[4]B_PSO)3种杯芳烃固定液上的热力学参数ΔH、ΔS、ΔG,然后用热力学及超热力学的方法探讨了杯芳烃对异构体的分子识别特性和保留机理。 相似文献
144.
An amperometric method for thé successive titration of calcium and magnesium with EGTA and EDTA respectively is proposed. The method is direct and rapid. Calcium and magnesium can be determined in waters (41.5 mg/l and 4.6 mg/l with a precision of ±1.15% and ±6.70%), in cements (66.7% CaO and 1.70% MgO with a precision of ±2% and ±8%), and in soils (16.5% CaCO3 and 1.8% MgCO3 with a precision of ±2.6% and ±5.5%). The results obtained are compared with those obtained by gravimetric or titrimctric methods. 相似文献
145.
将大气中的二氧化碳(CO2)转化为燃料或高附加值化学品是降低大气中CO2含量、 减缓温室效应的有效途径之一. 光催化CO2化学转化条件温和, 能耗低, 在CO2转化中占有重要地位. 金属-有机框架(MOF)基材料由于具有比表面积大、 光电性质优良和可调节性强等特点, 是CO2光催化转化的常用催化剂之一. 本文综合评述了近两年MOF基材料在光催化CO2还原反应、 CO2环加成反应和CO2羧基化反应中的应用, 阐释了MOF基材料在CO2光催化转化中的优势和局限性, 并展望了其未来发展. 相似文献
146.
Alpha-chymotrypsin (CT)/polyvinylpyrrolidone (PVP) composites was synthesized by combination of reverse micelles and CO(2). In this method, the two reverse micellar solutions containing CT and PVP, respectively, were first mixed, then compressed CO(2) was used as an antisolvent to precipitate the CT and PVP simultaneously and CT/PVP composites were successfully prepared. The morphology of the obtained CT/PVP composites was characterized by transmission electron microscopy (TEM). The FTIR spectra of the composites showed that there was interaction between CT and PVP. The storage activity of the enzyme immobilized on the polymer by this method was higher than that of the pure enzyme. This method has some advantages and can be easily applied to the synthesis of some other enzyme/polymer composites. 相似文献
147.
Chaoxing Zhang Jianling Zhang Xiaoying Feng Wei Li Yueju Zhao Buxing Han 《Colloids and surfaces. A, Physicochemical and engineering aspects》2008,324(1-3):167-170
Three surfactants, sodium dodecyl sulfate (SDS), cetyltrimethylammonium bromide (CTAB) and polyoxyethylene-80-sorbitan monooleate (Tween 80), were used to control the growth of CaCO3 crystals by carbonation route using Ca(OH)2 and compressed CO2. The obtained CaCO3 particles were characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD) techniques. The effects of surfactants on the morphology of the particles were studied. It was demonstrated that Tween 80 and SDS have obvious effect on the morphology of CaCO3 particles, while CTAB does not affect morphology considerably. The possible mechanism has been discussed on the basis of the binding of the surfactants to the certain face of the crystals. 相似文献
148.
Dohi H Périon R Durka M Bosco M Roué Y Moreau F Grizot S Ducruix A Escaich S Vincent SP 《Chemistry (Weinheim an der Bergstrasse, Germany)》2008,14(31):9530-9539
Heptosides are found in important bacterial glycolipids such as lipopolysaccharide (LPS), the biosynthesis of which is targeted for the development of novel antibacterial agents. This work describes the synthesis of a fluorinated analogue of ADP-L-glycero-beta-D-manno-heptopyranose, the donor substrate of the heptosyl transferase WaaC, which catalyzes the incorporation of this carbohydrate into LPS. Synthetically, the key step for the preparation of ADP-2F-heptose is the simultaneous and stereoselective installation of both the fluorine atom at C-2 and the phosphoryl group at C-1 through a selectfluor-mediated (selectfluor=1-chloromethyl-4-fluorodiazoniabicyclo[2.2.2]octane bis(triflate)) electrophilic addition/nucleophilic substitution involving a heptosylglycal. Therefore, we detail in this article 1) the stereoselective preparation of the key intermediates heptosylglycals, 2) the development of a new fluorophosphorylation procedure allowing an excellent beta-gluco stereoselectivity with "all-equatorial" glycals, 3) the synthesis of the target ADP-2F-heptose, and 4) some comments on the contacts observed between the fluorine atom of the final molecule and the protein in the crystallographic structure of heptosyltransferase WaaC. 相似文献
149.
Assembly of Mesoporous Metal–Organic Framework Templated by an Ionic Liquid/Ethylene Glycol Interface
下载免费PDF全文
![点击此处可从《Chemphyschem》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Xinxin Sang Prof. Jianling Zhang Li Peng Chengcheng Liu Xue Ma Prof. Buxing Han Guanying Yang 《Chemphyschem》2015,16(11):2317-2321
We propose a facile room‐temperature synthesis of a metal–organic framework (MOF) with a bimodal mesoporous structure (3.9 and 17‐28 nm) in an ionic liquid (IL)/ethylene glycol (EG) mixture. The X‐ray diffraction analysis reveals that MOF formation can be efficiently promoted by the presence of the EG/IL interface at room temperature. The MOFs with mesoporous networks are characterized by SEM and TEM. The formation mechanism of the mesoporous MOF in EG/IL mixture is investigated. It is proposed that the EG nanodroplets in the IL work as templates for the formation of the large mesopores. The as‐synthesized mesoporous metal–organic framework is an effective and reusable heterogeneous catalyst to catalyze the aerobic oxidation of benzylic alcohols. 相似文献
150.
利用预估校正-时域有限差分(PC-FDTD)法求解全波Maxwell-Bloch方程,研究介质粒子数密度(N)对飞秒Gauss型激光脉冲在Λ型三能级原子介质中传播及光谱特性的影响.结果表明:小面积2π脉冲在不同N介质中都不发生分裂,脉冲频谱基本没有新的高频成分产生,随N增大中心频率附近光谱强度明显减小.面积4π脉冲,在N较大的稀疏介质及稠密介质中都产生分裂,在稀疏介质中随N增大频谱展宽幅度及高频成分强度增大,但在稠密介质中频谱展宽变小且远小于N较大时的稀疏介质情况.大面积8π脉冲,脉冲分裂情况与4π脉冲情况相似,但随N增大频谱展宽幅度及高频成分强度单调增大,且在稠密介质中的频谱展宽幅度及高频成分强度远大于N较小的稀疏介质情况. 相似文献