全文获取类型
收费全文 | 1031篇 |
免费 | 53篇 |
国内免费 | 6篇 |
专业分类
化学 | 902篇 |
晶体学 | 2篇 |
力学 | 22篇 |
数学 | 27篇 |
物理学 | 137篇 |
出版年
2023年 | 13篇 |
2021年 | 15篇 |
2020年 | 29篇 |
2019年 | 18篇 |
2018年 | 13篇 |
2017年 | 8篇 |
2016年 | 24篇 |
2015年 | 19篇 |
2014年 | 28篇 |
2013年 | 30篇 |
2012年 | 47篇 |
2011年 | 67篇 |
2010年 | 26篇 |
2009年 | 33篇 |
2008年 | 47篇 |
2007年 | 48篇 |
2006年 | 62篇 |
2005年 | 66篇 |
2004年 | 49篇 |
2003年 | 30篇 |
2002年 | 48篇 |
2001年 | 43篇 |
2000年 | 29篇 |
1999年 | 19篇 |
1997年 | 11篇 |
1996年 | 6篇 |
1995年 | 5篇 |
1994年 | 12篇 |
1993年 | 12篇 |
1992年 | 18篇 |
1991年 | 13篇 |
1990年 | 17篇 |
1989年 | 14篇 |
1988年 | 13篇 |
1987年 | 12篇 |
1986年 | 8篇 |
1985年 | 13篇 |
1982年 | 6篇 |
1981年 | 8篇 |
1979年 | 13篇 |
1978年 | 4篇 |
1977年 | 8篇 |
1976年 | 12篇 |
1975年 | 6篇 |
1974年 | 15篇 |
1973年 | 9篇 |
1972年 | 5篇 |
1971年 | 5篇 |
1968年 | 4篇 |
1967年 | 7篇 |
排序方式: 共有1090条查询结果,搜索用时 296 毫秒
61.
Amine‐Responsive Adaptable Nanospaces: Fluorescent Porous Coordination Polymer for Molecular Recognition 下载免费PDF全文
Ritesh Haldar Prof. Ryotaro Matsuda Prof. Susumu Kitagawa Prof. Subi J. George Prof. Tapas Kumar Maji 《Angewandte Chemie (International ed. in English)》2014,53(44):11772-11777
Flexible and dynamic porous coordination polymers (PCPs) with well‐defined nanospaces composed of chromophoric organic linkers provide a scaffold for encapsulation of versatile guest molecules through noncovalent interactions. PCPs thus provide a potential platform for molecular recognition. Herein, we report a flexible 3D supramolecular framework {[Zn(ndc)(o‐phen)]?DMF}n (o‐phen=1,10‐phenanthroline, ndc=2,6‐napthalenedicarboxylate) with confined nanospaces that can accommodate different electron‐donating aromatic amine guests with selective turn‐on emission signaling. This system serves as a molecular recognition platform through an emission‐readout process. Such unprecedented tunable emission with different amines is attributed to its emissive charge‐transfer (CT) complexation with o‐phen linkers. In certain cases this CT emission is further amplified by energy transfer from the chromophoric linker unit ndc, as evidenced by single‐crystal X‐ray structural characterization. 相似文献
62.
Selective Generation of Formamides through Photocatalytic CO2 Reduction Catalyzed by Ruthenium Carbonyl Compounds 下载免费PDF全文
Dr. Katsuaki Kobayashi Dr. Takashi Kikuchi Prof. Susumu Kitagawa Prof. Koji Tanaka 《Angewandte Chemie (International ed. in English)》2014,53(44):11813-11817
The selective formation of dialkyl formamides through photochemical CO2 reduction was developed as a means of utilizing CO2 as a C1 building block. Photochemical CO2 reduction catalyzed by a [Ru(bpy)2(CO)2]2+ (bpy: 2,2′‐bipyridyl)/[Ru(bpy)3]2+/Me2NH/Me2NH2+ system in CH3CN selectively produced dimethylformamide. In this process a ruthenium carbamoyl complex ([Ru(bpy)2(CO)(CONMe2)]+) formed by the nucleophilic attack of Me2NH on [Ru(bpy)2(CO)2]2+ worked as the precursor to DMF. Thus Me2NH acted as both the sacrificial electron donor and the substrate, while Me2NH2+ functioned as the proton source. Similar photochemical CO2 reductions using R2NH and R2NH2+ (R=Et, nPr, or nBu) also afforded the corresponding dialkyl formamides (R2NCHO) together with HCOOH as a by‐product. The main product from the CO2 reduction transitioned from R2NCHO to HCOOH with increases in the alkyl chain length of the R2NH. The selectivity between R2NCHO and HCOOH was found to depend on the rate of [Ru(bpy)2(CO)(CONR2)]+ formation. 相似文献
63.
Dr. Ming-Shui Yao Prof. Jia-Jia Zheng Ai-Qian Wu Prof. Gang Xu Sanjog S. Nagarkar Gen Zhang Masahiko Tsujimoto Prof. Shigeyoshi Sakaki Prof. Satoshi Horike Prof. Kenichi Otake Prof. Susumu Kitagawa 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(1):178-182
Single-ligand-based electronically conductive porous coordination polymers/metal–organic frameworks (EC-PCPs/MOFs) fail to meet the requirements of numerous electronic applications owing to their limited tunability in terms of both conductivity and topology. In this study, a new 2D π-conjugated EC-MOF containing copper units with mixed trigonal ligands was developed: Cu3(HHTP)(THQ) (HHTP=2,3,6,7,10,11-hexahydrotriphenylene, THQ=tetrahydroxy-1,4-quinone). The modulated conductivity (σ≈2.53×10−5 S cm−1 with an activation energy of 0.30 eV) and high porosity (ca. 441.2 m2 g−1) of the Cu3(HHTP)(THQ) semiconductive nanowires provided an appropriate resistance baseline and highly accessible areas for the development of an excellent chemiresistive gas sensor. 相似文献
64.
Ming‐Shui Yao Jia‐Jia Zheng Ai‐Qian Wu Gang Xu Sanjog S. Nagarkar Gen Zhang Masahiko Tsujimoto Shigeyoshi Sakaki Satoshi Horike Kenichi Otake Susumu Kitagawa 《Angewandte Chemie (International ed. in English)》2020,59(1):172-176
Single‐ligand‐based electronically conductive porous coordination polymers/metal–organic frameworks (EC‐PCPs/MOFs) fail to meet the requirements of numerous electronic applications owing to their limited tunability in terms of both conductivity and topology. In this study, a new 2D π‐conjugated EC‐MOF containing copper units with mixed trigonal ligands was developed: Cu3(HHTP)(THQ) (HHTP=2,3,6,7,10,11‐hexahydrotriphenylene, THQ=tetrahydroxy‐1,4‐quinone). The modulated conductivity (σ≈2.53×10?5 S cm?1 with an activation energy of 0.30 eV) and high porosity (ca. 441.2 m2 g?1) of the Cu3(HHTP)(THQ) semiconductive nanowires provided an appropriate resistance baseline and highly accessible areas for the development of an excellent chemiresistive gas sensor. 相似文献
65.
66.
Akihiro Kitashoji Kosei Kitagawa Dr. Akimasa Fujihara Prof. Dr. Tomoyuki Yatsuhashi 《Chemphyschem》2020,21(9):847-852
A multiply charged molecule expands the range of a mass window and is utilized as a precursor to provide rich sequence coverage; however, reflectron time-of-flight mass spectrometer has not been well applied to the product ion analysis of multiply charged precursor ions. Here, we demonstrate that the range of the mass-to-charge ratio of measurable product ions is limited in the cases of multiply charged precursor ions. We choose C6F6 as a model molecule to investigate the reactions of multiply charged molecular cations formed in intense femtosecond laser fields. Measurements of the time-of-flight spectrum of C6F6 by changing the potential applied to the reflectron, combined with simulation of the ion trajectory, can identify the species detected behind the reflectron as the neutral species and/or ions formed by the collisional charge transfer. Moreover, the metastable ion dissociations of doubly and triply charged C6F6 are identified. The detection of product ions in this manner can diminish interference by the precursor ion. Moreover, it does not need precursor ion separation before product ion analysis. These advantages would expand the capability of mass spectrometry to obtain information about metastable ion dissociation of multiply charged species. 相似文献
67.
Inside Cover: Enhancement of Light Absorption Ability of Synthetic Chlorophyll Derivatives by Conjugation with a Difluoroboron Diketonate Group (Chem. Eur. J. 29/2016) 下载免费PDF全文
68.
69.
Utilization of a metalloligand, ([Cu(2,4-pydca)2(H2O)].2Et3NH) (1) (2,4-pydca = pyridine-2,4-dicarboxylate), as a building unit provides a novel porous coordination polymer, ([ZnCu(2,4-pydca)2(H2O)3(DMF)].DMF)n (2), in which the Zn(II) ion at the node of the network acts as a linker and the Cu(II) ion in the channel wall is available for guest-coordination. 相似文献
70.