全文获取类型
收费全文 | 353篇 |
免费 | 16篇 |
国内免费 | 62篇 |
专业分类
化学 | 387篇 |
晶体学 | 1篇 |
综合类 | 16篇 |
物理学 | 27篇 |
出版年
2024年 | 2篇 |
2023年 | 12篇 |
2022年 | 40篇 |
2021年 | 27篇 |
2020年 | 15篇 |
2019年 | 14篇 |
2018年 | 17篇 |
2017年 | 12篇 |
2016年 | 15篇 |
2015年 | 8篇 |
2014年 | 7篇 |
2013年 | 27篇 |
2012年 | 13篇 |
2011年 | 15篇 |
2010年 | 15篇 |
2009年 | 20篇 |
2008年 | 25篇 |
2007年 | 15篇 |
2006年 | 24篇 |
2005年 | 19篇 |
2004年 | 10篇 |
2003年 | 14篇 |
2002年 | 13篇 |
2001年 | 3篇 |
2000年 | 6篇 |
1999年 | 10篇 |
1998年 | 10篇 |
1997年 | 6篇 |
1996年 | 3篇 |
1995年 | 2篇 |
1994年 | 4篇 |
1993年 | 2篇 |
1992年 | 1篇 |
1990年 | 1篇 |
1989年 | 1篇 |
1986年 | 1篇 |
1984年 | 1篇 |
1982年 | 1篇 |
排序方式: 共有431条查询结果,搜索用时 0 毫秒
391.
Polysaccharide (PS) nanoparticles (NP) are fascinating materials that combine huge application potential with the unique beneficial features of natural biopolymers. Different types of PS‐NP can be distinguished depending on the basic preparation principles (top‐down vs bottom‐up vs coating of nanomaterials) and the material from which they are obtained (native PS vs chemically modified PS derivatives vs nanocomposites). This review provides a comprehensive overview of an approach towards PS‐NP that has gained rapidly increasing interest within the last decade; the nanoself‐assembling of hydrophobic PS derivatives. This facile process is easy to perform and offers a broad structural diversity in terms of the PS backbone and the additional functionalities that can be introduced. Fundamental principles of different NP preparation techniques along with useful characterization methods are presented in this work. A comprehensive summary of PS‐NP prepared by different techniques and with various PS backbones and types/amounts of hydrophobic substituents is given. The intention is to demonstrate how different parameters determine the size, size distribution, and zeta‐potential of the particles. Moreover, application trends in biomedical areas are highlighted in which tailored functional PS‐NP are evaluated and constantly developed further. 相似文献
392.
Lei Shi Kaoshan Chen Qun Dong Jinian Fang Kan Ding 《Frontiers of Chemistry in China》2008,3(2):209-212
A water-soluble polysaccharide (CPS-0) was obtained from the root of Cudrania tricuspidata (Carr.) Bur., by hot water extraction (70°C), deproteination using enzymolysis and Sevag method, precipitation with ethanol,
and fractionation through DEAE-Sephadex A-50 chromatography. The purity of CPS-0 was determined by HPLC and the structure
was elucidated by monosaccharide composition analysis, methylation analysis, GC, GC-MS, NMR spectral (1H-NMR, 13C-NMR, HMQC), UV, IR, and elemental analysis. The CPS-0 was found to contain glucose residues only. The average repeating
unit is a decasaccharide having a backbone consisting of 1,4-linked α-D-glucopyranosyl residues to which the side chain consisting of terminal and 1,4-linked α-D-glucopyranosyl residues was attached at position 6 of the branching residues.
__________
Translated from Chemical Journal of Chinese Universities, 2007, 28(6): 1088–1091 [译自: 高等学校化学学报] 相似文献
393.
A bienzymatic supramolecular assembly of CAT and SOD is reported. CAT was chemically glycosilated with CD branched CMC and then associated with SOD modified with 1-adamantane carboxylic acid. SOD was remarkably resistant to inactivation by H(2)O(2) and its anti-inflammatory activity was 4.5-fold increased after supramolecular association with the modified CAT form. [structure: see text] 相似文献
394.
395.
396.
水溶性凝胶渗透色谱测定芸芝多糖各组分的分子量及相对含量 总被引:2,自引:0,他引:2
用水溶性凝胶渗透色谱法研究了芸芝多糖在水溶性凝胶柱上的吸附影响因素,建立了最佳分离、测试条件,成功地将芸芝多糖的混合物分离为三个组分,并测试各组分的分子量分别为1190000;796000;552000。各组分相对百分含量分别为83.6%,8.9%,7.5%。 相似文献
397.
动态膜渗透压法测定生漆多糖水溶液 总被引:2,自引:0,他引:2
<正> 生漆是一种性能优异的超耐久涂料,其主要成份为漆酚、漆酶、糖蛋白、多糖和水。多糖由D-半乳糖(65%),4-O-甲基-D-葡萄糖醛酸(24%),D-葡萄糖醛酸(3%),L-阿拉伯糖(4%)和鼠李糖(3%)组成。它带大量支链,在侧链上有大约1/4mol羧基从而显示聚电解质溶液性质。 相似文献
398.
《Journal of separation science》2018,41(6):1450-1459
Thirteen pairs of enantiomers belonging to the same structural family (phenylthiohydantoin‐amino acids) were analyzed on two polysaccharide chiral stationary phases, namely, tris‐(3,5‐dimethylphenylcarbamate) of amylose (Chiralpak AD‐H) or cellulose (Chiralcel OD‐H) in supercritical fluid chromatography with a carbon dioxide/methanol mobile phase (90:10 v/v). Five different temperatures (5, 10, 20, 30, 40°C) were applied to evaluate the thermodynamic behavior of these enantioseparations. On the cellulose stationary phase, the retention, and separation trends were most similar among the set of probe analytes, suggesting that the chiral cavities in this stationary phase have little diversity, or that all analytes accessed the same cavities. Conversely, the retention and separation trends on the amylose phase were much more diverse, and could be related to structural differences among the set of probe analytes (carbon chain length in the amino acid residue, secondary amine in proline, existence of covalent rings, or formation of pseudo‐rings via intramolecular hydrogen bonds). The large variability of behaviors on the amylose phase suggests that the chiral‐binding sites in this chiral stationary phase have more variety than on the cellulose phase, and that the analytes did access different cavities. 相似文献
399.
灵芝多糖的结构特征分析 总被引:5,自引:0,他引:5
采用沸水回流法从灵芝子实体中提取多糖,经Sevage法除蛋白,乙醇沉淀,离心、透析、膜分离,浓缩、冻干后得灵芝多糖。经HIO4氧化、Smith降解及甲基化反应,并利用多糖及刚果红混合液在碱性溶液中的波长的红移变化,通过UV-VIS,IR,GC,GC-MS,NMR对灵芝水提多糖的结构特征及三螺旋体结构进行分析研究。结果表明:灵芝多糖含有三螺旋体构型,GC-MS分析灵芝多糖的主要单糖组分为葡萄糖,还有少量的半乳糖、甘露糖、木糖和艾杜糖,IR及1HNMR分析多糖为β-构型,HIO4氧化、Smith降解和甲基化分析表明:多糖主要为(1→3)糖苷键连接构型,并伴有少量的1→6位支链键连接的结构,灵芝多糖是由D-葡萄糖单元通过β-(1→3)糖苷键连接葡聚多糖,其主要构型特征为(1→3)β-D-线性连接的骨架结构。 相似文献
400.