全文获取类型
收费全文 | 502篇 |
免费 | 48篇 |
国内免费 | 88篇 |
专业分类
化学 | 542篇 |
力学 | 7篇 |
综合类 | 5篇 |
数学 | 20篇 |
物理学 | 64篇 |
出版年
2021年 | 1篇 |
2019年 | 3篇 |
2018年 | 1篇 |
2016年 | 1篇 |
2015年 | 2篇 |
2014年 | 30篇 |
2013年 | 46篇 |
2012年 | 46篇 |
2011年 | 7篇 |
2010年 | 2篇 |
2009年 | 5篇 |
2008年 | 20篇 |
2007年 | 19篇 |
2006年 | 15篇 |
2005年 | 18篇 |
2004年 | 28篇 |
2003年 | 35篇 |
2002年 | 86篇 |
2001年 | 193篇 |
2000年 | 33篇 |
1999年 | 22篇 |
1998年 | 10篇 |
1997年 | 8篇 |
1996年 | 4篇 |
1995年 | 3篇 |
排序方式: 共有638条查询结果,搜索用时 31 毫秒
591.
YE YANQIAN * 《数学年刊B辑(英文版)》1997,(3)
LIMITCYCLESANDBIFURCATIONCURVESFORTHEQUADRATICDIFFERENTIALSYSTEM(II)m=0HAVINGTHREEANTISADDLES(I)YEYANQIANAbstractAsaconti... 相似文献
592.
593.
594.
595.
Jin Cui Ming Jie Zhang~* Xiang Qian Wang Nai Jing Cui School of Science Tianjin University Tianjin China 《中国化学快报》2008,(3)
By the addition of rice wine koji,enhancement of the reactivity was observed for the baker's yeast reduction ofβ-keto esters into (S)-β-hydroxy esters with high enantiomeric purity (73-98%). 相似文献
596.
Jian She Zhang Jiu Gao Yu~* Ying Wu Xiao Fei Ma School of Science Tianjin University Tianjin PR China 《中国化学快报》2008,19(4):395-398
In this paper,aliphatic amidediol was synthesized and mixed with glycerol used as a plasticizer for preparing thermoplastic starch(AGPTPS).The yield of aliphatic amidediol was 91%.FF-IR expressed that the mixture of aliphatic amidediol and glycerol formed stronger and stable hydrogen bond with starch molecules compared to the native cornstarch.By scanning electron microscope(SEM)native cornstarch granules were proved to transfer to a homogeneous continuous system.After being stored for a period time at room temperature,the mechanical properties of AGPTPS were also studied.As a mixed plasticizer,aliphatic amidediol and glycerol would be practical to extend TPS application scopes. 相似文献
597.
Hui Tang You Jun Zhou~* Yao Wu Li Jia Guo Lv Can Hui Zheng Jun Chen Ju Zhu~* Department of Medicinal Chemistry School of Pharmacy Second Military Medical University Shanghai China 《中国化学快报》2008,19(3):264-268
Novel chiral tetralin compounds were designed and synthesized, and their antifungal activities in vitro were tested. The results showed that all of target compounds had potent antifungal activities, and were stronger than that of control compounds tetrahydroisoquinolines. The binding model of lead molecules in the active site of CYP51 of Candida albicans showed that lead compound specifically interacted with the amino acids residues in the active site, without binding with the heme of CYP51, which was different from azole antifungal drugs. The present study might afford a novel lead molecule to develop non-azole CYP51 inhihitars of fungi. 相似文献
598.
Synthesis and cytotoxic activity of novel curcumin analogues 总被引:3,自引:0,他引:3
Qin Zhang Yao Fu Hao Wei Wang Tao Gong Yong Qin Zhi Rong Zhang~* Key Laboratory of Drug Targeting Drug Delivery Systems Ministry of Education West China School of Pharmacy Sichuan University Chengdu China 《中国化学快报》2008,19(3):281-285
Five novel curcumin analogues bearing different substituents at 4-position of phenyl group were synthesized. Their structures were confirmed by NMR and HRMS spectrum. Their cytotoxic activities against six tumor cell lines were tested by the standard MTT assay in vitro. The results indicated that four analogues (1A-1C, 1E) with solubilizing moieties showed selective potent cytotoxicity against HepG2, HeLa and CT26 cell lines, and analogue 1A and 1C exhibited more potent cytotoxicity than curcumin against CT26 cell line. It was suggested that introduction of appropriate substituents to 4-position of phenyl group might be a potential option for structural modification of curcumin. 相似文献
599.
Yi Luo Ping Zhong~* Xiao Hong Zhang Qiu Lian Lin Ye Na Chen College of Chemistry Materials Science Wenzhou University Wenzhou China 《中国化学快报》2008,19(4):383-386
Two species of N-arylpyrazoles containing active amino group were synthesized.And formylations of N-arylpyazoles containing amino in different position of pyrazole rings using Vilsmeier-Haack reaction gave a series of useful pyrazole intermediates.The important features of this protocol were cheap materials,easy process,mild reaction conditions and good yield of products. 相似文献
600.
Hui Pan~* Mei Qi Zhi Jun Zhang Laboratory of Special Functional Material Henan University Kaifeng PR China 《中国化学快报》2008,19(4):435-437
The radical polymerization of maleic anhydride(MA),styrene(ST)with the vinyl groups introduced onto the surface of the nano-sized silica via solution polymerization method was developed.The methacryloxypropyl nano-sized silica(MPNS)was used as macromonomer and polymerized with maleic anhydride and styrene by initiating with BPO in toluene.The structure and properties of MPNS/SMA nano-composite were characterized by FT-IR spectra and TEM.Meanwhile,it was applied as tanning agent compared with the traditional styrene-maleic anhydride copolymer in leather.It was found that the applied leather had better quality characteristics with the addition of the nano-sized silica. 相似文献