全文获取类型
收费全文 | 509篇 |
免费 | 61篇 |
国内免费 | 80篇 |
专业分类
化学 | 529篇 |
晶体学 | 4篇 |
力学 | 7篇 |
综合类 | 5篇 |
数学 | 20篇 |
物理学 | 85篇 |
出版年
2024年 | 1篇 |
2022年 | 1篇 |
2021年 | 1篇 |
2020年 | 3篇 |
2019年 | 1篇 |
2018年 | 1篇 |
2017年 | 2篇 |
2016年 | 3篇 |
2014年 | 29篇 |
2013年 | 50篇 |
2012年 | 46篇 |
2011年 | 10篇 |
2010年 | 3篇 |
2009年 | 4篇 |
2008年 | 20篇 |
2007年 | 19篇 |
2006年 | 20篇 |
2005年 | 21篇 |
2004年 | 28篇 |
2003年 | 35篇 |
2002年 | 85篇 |
2001年 | 194篇 |
2000年 | 31篇 |
1999年 | 20篇 |
1998年 | 10篇 |
1997年 | 8篇 |
1996年 | 1篇 |
1995年 | 3篇 |
排序方式: 共有650条查询结果,搜索用时 15 毫秒
1.
Hong Zhu * Patrick Phelan Tianhua Duan Gregory Raupp H. J. S. Fernando Beijing Institute of Microbiology Epidemiology Beijing P. R. China Department of Mechanical Aerospace Engineering Arizona State University Tempe Department of Chemical Materials Engineering Arizona State University Tempe *Author to whom correspondence should be addressed. Tel: -- E-mail: zhuhong@hotmail.com 《中国颗粒学报》2003,1(3):119-123
1.IntroductionBioaerosolsaremicroorganismsorparticles,gases,vapors,orfragmentsofbiologicalorigin(i.e.,aliveorreleasedfromalivingorganism)thatexistintheair.Bioaerosolsareeverywhereintheenvironment.Underfavorableconditions,bioaerosolsareabletogrowandpropagateonavarietyofbuildingmaterialsandindoorsurfaces,causingindoorairpollution.Therefore,owingtotheirubiquitouspresenceinnature,bioaerosolsasapollutionsourcearealmostinevitableinarangeofenclosedenvironmentsandincommunityair(Kodama&McGee,1986;Lig… 相似文献
2.
Ruoyu Hong * Jianmin Ding Guoliang Zheng College of Chemistry Chemical Engineering Soochow University Suzhou P. R. China Institute of Process Engineering Chinese Academy of Sciences Beijing P. R. China IBM HYDA/- C Highway North Rochester MN USA *Author to whom correspondence should be addressed. E-mail: rhong@suda.edu.cn 《中国颗粒学报》2004,2(5):207-214
1. Introduction1.1 Silica nanoparticles and synthesis methods Silica (SiO2) nanoparticles are widely used in industry asan active filler for polymer reinforcement, a rheologicaladditive in fluids, a free flow agent in powders, and anagent for chemical mechanical polishing during IC (inte-grated circuit) fabrication (Sniegowski & de Boer, 2000).Silica powder is also used for producing silicon carbide(Koc & Cattamanchi, 1998) or opaque silica aerosols (Leeet al., 1995). Many methods can … 相似文献
3.
采用分子动力学(MD)模拟计算,对Pd82Si18合金快凝过程中基本原子团簇的遗传特性、演化趋势和结构稳定性进行了研究.团簇类型指数法(CTIM)分析表明:非晶固体中Si原子为中心的(102/14418/1551)双帽阿基米德反棱柱(BSAP)团簇数目占据优势.快凝过程中,BSAP结构团簇具有最大的遗传分数,并且其他以Si原子为中心的Kasper团簇大多都会向BSAP结构团簇转变.通过对Si原子为中心的Kasper基本团簇电子性质第一性原理计算发现,体系中BSAP团簇的结合能最低,结构稳定性较高,与分子动力学计算结果一致. 相似文献
4.
5.
研究了 OFDMA 中继下行链路通信系统中的动态资源分配问题,提出了一种可以保证用户最低 QoS 需求的资源分配算法.首先在简化资源优化问题的过程中,采用等功率分配方法以降低算法复杂度,然后通过拉格朗日松弛优化方法推导出了子载波分配和中继选择最优解,并在此基础上引入用户速率权衡因子,根据速率权衡因子越大的用户,越具有选择子载波和中继的优先权这一准则进行子载波分配和中继选择.仿真结果表明:新算法能够获得较高的系统容量,同时也能很好地保证不同用户的最低速率需求. 相似文献
6.
7.
LIU KaiQiang PENG JunXia XUE Min YAN Ni LIU Jing & FANG Yu* Key Laboratory of Applied Surface Colloid Chemistry Ministry of Education School of Chemistry Materials Science Shaanxi Normal University Xi’an China 《中国科学B辑(英文版)》2011,(3)
Five new diacid amides of di-cholesteryl L-glycinates were designed and prepared.The compounds with linkers containing 0,1, 2,3,or 4 methylene units are denoted as 1,2,3,4,and 5,respectively.Their gelation behaviors in 25 solvents were tested as novel low-molecular-mass organic gelators(LMOGs).It was shown that the length of the linker connecting the two-cholesteryl residues in a gelator plays a crucial role in the gelation behavior of the compound.1 gels 11 of the 25 solvents tested at a concentration lowe... 相似文献
8.
9.
Hong Ping HE Yue Mao SHEN Xiao Sheng YANG Bin Gui WANG Ling LI Xiao Jiang HAO * Laboratory of Phytochemistry Kunming Institute of Botany the Chinese Academy of Sciences Kunming . The Key Laboratory of Chemistry for Natural Prod 《中国化学快报》2001,(1)
Spiraea japonica L. (Rosaceae) is widely distributed in Yunnan Provence, P. R. China. Previous chemical investigations on S. japonica and its varieties have led to the report of 7 new atisane-type diterpenoids and 38 new diterpene alkaloids of atisine- and hetisine-type1-11. This paper describes the isolation and structure elucidation of two new diterpene alkaloids named spiratines A and B (1-2). Their structures were elucidated on the basis of 1D and 2D NMR experiments (HMQC, HMBC, 1… 相似文献
10.
1 INTRODUCTIONOrganophosphorus compounds are ubiquitous in nature and they have broad applications in the fields of agriculture and medicine. During the past two decades, (-ketophosphonates and their derivatives have attracted considerable attention because these compounds are endowed with special physical, chemical and pharmacological properties due to the proximity of the carbonyl and the phosphoryl groups[1~6]. For example, it is well known that phosphonoformic acid (PFA) is effectiv… 相似文献