全文获取类型
收费全文 | 24489篇 |
免费 | 4336篇 |
国内免费 | 3077篇 |
专业分类
化学 | 17437篇 |
晶体学 | 306篇 |
力学 | 1710篇 |
综合类 | 231篇 |
数学 | 2577篇 |
物理学 | 9641篇 |
出版年
2024年 | 15篇 |
2023年 | 515篇 |
2022年 | 537篇 |
2021年 | 742篇 |
2020年 | 1075篇 |
2019年 | 954篇 |
2018年 | 834篇 |
2017年 | 732篇 |
2016年 | 1185篇 |
2015年 | 1144篇 |
2014年 | 1454篇 |
2013年 | 1751篇 |
2012年 | 2225篇 |
2011年 | 2311篇 |
2010年 | 1542篇 |
2009年 | 1383篇 |
2008年 | 1660篇 |
2007年 | 1433篇 |
2006年 | 1424篇 |
2005年 | 1180篇 |
2004年 | 888篇 |
2003年 | 756篇 |
2002年 | 680篇 |
2001年 | 555篇 |
2000年 | 497篇 |
1999年 | 574篇 |
1998年 | 426篇 |
1997年 | 408篇 |
1996年 | 473篇 |
1995年 | 393篇 |
1994年 | 375篇 |
1993年 | 283篇 |
1992年 | 260篇 |
1991年 | 221篇 |
1990年 | 201篇 |
1989年 | 157篇 |
1988年 | 155篇 |
1987年 | 100篇 |
1986年 | 92篇 |
1985年 | 68篇 |
1984年 | 52篇 |
1983年 | 40篇 |
1982年 | 31篇 |
1981年 | 33篇 |
1980年 | 18篇 |
1979年 | 9篇 |
1974年 | 5篇 |
1970年 | 12篇 |
1957年 | 5篇 |
1937年 | 5篇 |
排序方式: 共有10000条查询结果,搜索用时 109 毫秒
81.
Hong Chengming Wang Xiaojun Pan Zhigang Zhang Yifan 《Journal of Thermal Analysis and Calorimetry》2015,120(1):427-438
Journal of Thermal Analysis and Calorimetry - The saturated aliphatic binary carboxylic acid, including succinic acid, adipic acid and sebacic acid, were used to improve the curing process of... 相似文献
82.
Donor-acceptor type copolymers have wide applications in organic field-effect transistors and organic photovoltaic devices. Thieno[3,4-c]pyrrole-4,6-dione (TPD), as an electron-withdrawing unit, has been widely used in D-A type copolymers recently. Till now, the highest power conversion efficiency and mobility of TPD-based copolymers are over 8% and 1.0 cm2 V-1 s-1 respectively. In this review, the recent progress of TPD-based copolymers in organic solar cells and organic transistors is summarized. 相似文献
83.
Microchimica Acta - Inspired by water-soluble sacrificial template strategies, we have synthesized crystals of silver chloride (AgCl) consisting of a well-defined cubic exterior and a hollow... 相似文献
84.
85.
86.
87.
Dr. Heng Liao Dr. Liu Zhong Dr. Zefan Xiao Dr. Ting Zheng Prof. Haiyang Gao Prof. Qing Wu 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(39):14048-14055
A series of novel α‐diamine nickel complexes, (ArNH‐C(Me)‐(Me)C‐NHAr)NiBr2, 1 : Ar=2,6‐diisopropylphenyl, 2 : Ar=2,6‐dimethylphenyl, 3 : Ar=phenyl), have been synthesized and characterized. X‐ray crystallographic analysis showed that the coordination geometry of the α‐diamine nickel complexes is markedly different from conventional α‐diimine nickel complexes, and that the chelate ring (N‐C‐C‐N‐Ni) of the α‐diamine nickel complex is significantly distorted. The α‐diamine nickel catalysts also display different steric effects on ethylene polymerization in comparison to the α‐diimine nickel catalyst. Increasing the steric hindrance of the α‐diamine ligand by substitution of the o‐methyl groups with o‐isopropyl groups leads to decreased polymerization activity and molecular weight; however, catalyst thermal stability is significantly enhanced. Living polymerizations of ethylene can be successfully achieved using 1 /Et2AlCl at 35 °C or 2 /Et2AlCl at 0 °C. The bulky α‐diamine nickel catalyst 1 with isopropyl substituents can additionally be used to control the branching topology of the obtained polyethylene at the same level of branching density by tuning the reaction temperature and ethylene pressure. 相似文献
88.
A Hexagonal Covalent Porphyrin Framework as an Efficient Support for Gold Nanoparticles toward Catalytic Reduction of 4‐Nitrophenol 下载免费PDF全文
Zheng‐Dong Ding Yu‐Xia Wang Sai‐Fei Xi Prof. Dr. Yunxing Li Prof. Dr. Zaijun Li Prof. Dr. Xuehong Ren Prof. Dr. Zhi‐Guo Gu 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(47):17029-17036
A hexagonal porphyrin‐based porous organic polymer, namely, CPF‐1, was constructed by 3+2 ketoenamine condensation of the C2‐symmetric porphyrin diamine 5,15‐bis(4‐aminophenyl)‐10,20‐diphenylporphyrin and 1,3,5‐triformylphloroglucinol. This material exhibits permanent porosity and excellent thermal and chemical stability. CPF‐1 can be employed as a superior supporting substrate to immobilize Au nanoparticles (NPs) as a result of the strong interactions between Au NPs and the CPF support. An Au@CPF‐1 hybrid was synthesized by an interfacial solution infiltration method with NaBH4 as reducing agent. Au NPs (5 nm) grew on CPF‐1 and were distributed without aggregation. Moreover, Au@CPF‐1 exhibits superior catalytic activity compared to many other reported Au‐based catalysts for the reduction of 4‐nitrophenol in the presence of NaBH4. In addition, Au@CPF‐1 has excellent stability and recyclability, and it can be reused for three successive reaction cycles without loss of activity. The dense distribution of phenyl rings on the channel walls of the CPF support can reasonably be regarded as the active sites that adsorb the 4‐nitrophenol molecule through hydrogen‐bonding and C?H ??? π interactions, as was confirmed by the X‐ray structure of model compound DAPP‐Benz. 相似文献
89.
90.
Bimetallic Gold(I) Complexes with Ethynyl‐Helicene and Bis‐Phosphole Ligands: Understanding the Role of Aurophilic Interactions in their Chiroptical Properties 下载免费PDF全文
Dr. Mehdi El Sayed Moussa Dr. Hui Chen Zuoyong Wang Dr. Monika Srebro‐Hooper Dr. Nicolas Vanthuyne Dr. Soizic Chevance Prof. Christian Roussel Prof. J. A. Gareth Williams Prof. Jochen Autschbach Prof. Régis Réau Prof. Zheng Duan Dr. Christophe Lescop Dr. Jeanne Crassous 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(17):6075-6086
Monometallic gold(I)‐alkynyl‐helicene complexes ( 1 a , b ) and bimetallic gold(I)‐alkynyl‐helicene architectures featuring the presence ( 2 a , b ) or absence ( 3 a , b ) of aurophilic intramolecular interactions were prepared by using different types of phosphole ligands (mono‐phosphole L1 or bis‐phospholes L2 , 3 ). The influence of the AuI d10 metal center(s) on the electronic, photophysical, and chiroptical properties of these unprecedented phosphole‐gold(I)‐alkynyl‐helicene complexes was examined. Experimental and theoretical results highlight the importance of ligand‐to‐ligand‐type charge transfers and the strong effect of the presence or absence of AuI–AuI interactions in 2 a , b . 相似文献