全文获取类型
收费全文 | 1545篇 |
免费 | 288篇 |
国内免费 | 121篇 |
专业分类
化学 | 1190篇 |
晶体学 | 14篇 |
力学 | 85篇 |
综合类 | 3篇 |
数学 | 112篇 |
物理学 | 550篇 |
出版年
2024年 | 9篇 |
2023年 | 31篇 |
2022年 | 41篇 |
2021年 | 70篇 |
2020年 | 58篇 |
2019年 | 62篇 |
2018年 | 57篇 |
2017年 | 41篇 |
2016年 | 74篇 |
2015年 | 82篇 |
2014年 | 82篇 |
2013年 | 97篇 |
2012年 | 152篇 |
2011年 | 151篇 |
2010年 | 96篇 |
2009年 | 80篇 |
2008年 | 112篇 |
2007年 | 97篇 |
2006年 | 90篇 |
2005年 | 95篇 |
2004年 | 57篇 |
2003年 | 37篇 |
2002年 | 41篇 |
2001年 | 25篇 |
2000年 | 26篇 |
1999年 | 25篇 |
1998年 | 17篇 |
1997年 | 20篇 |
1996年 | 16篇 |
1995年 | 18篇 |
1994年 | 12篇 |
1993年 | 7篇 |
1992年 | 11篇 |
1991年 | 19篇 |
1990年 | 12篇 |
1989年 | 2篇 |
1988年 | 3篇 |
1987年 | 7篇 |
1985年 | 3篇 |
1984年 | 1篇 |
1983年 | 5篇 |
1982年 | 1篇 |
1981年 | 1篇 |
1980年 | 4篇 |
1979年 | 1篇 |
1978年 | 1篇 |
1976年 | 2篇 |
1974年 | 1篇 |
1947年 | 1篇 |
1946年 | 1篇 |
排序方式: 共有1954条查询结果,搜索用时 15 毫秒
71.
Zhu Xiaoyang Wang Jing Chai Lulu Tang Guangshi Wan Kangni Pan Junqing 《Journal of Solid State Electrochemistry》2022,26(5):1163-1173
Journal of Solid State Electrochemistry - In this work, nanorods like bimetallic Zn/Mn metal–organic-frameworks (MOFs) are proposed as the precursor for preparing MnxOy/porous carbon... 相似文献
72.
Dr. You Xu Xingjie Chai Tianlun Ren Hongjie Yu Shuli Yin Dr. Ziqiang Wang Prof. Dr. Xiaonian Li Prof. Dr. Liang Wang Dr. Hongjing Wang 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(70):16074-16080
The realization of water electrolysis on the basis of highly active, cost-effective electrocatalysts is significant yet challenging for achieving sustainable hydrogen production from water. Herein, N-doped Ni3S2/N-doped MoS2 1D hetero-nanowires supported by Ni foam (N-Ni3S2/N-MoS2/NF) are readily synthesized through a chemical transformation strategy by using NiMoO4 nanowire array growth on Ni foam (NiMoO4/NF) as the starting material. With the in situ generation of Ni3S2/MoS2 heterointerfaces within nanowires and the incorporation of N− anions, an extraordinary hydrophilic nature with abundant, well-exposed active sites and optimal reaction dynamics for both oxidation and reduction of water are obtained. Attributed to these properties, as-converted N-Ni3S2/N-MoS2/NF exhibits highly efficient electrocatalytic activities for both hydrogen and oxygen evolution reactions under alkaline conditions. The superior bifunctional properties of N-Ni3S2/N-MoS2/NF enable it to effectively catalyze the overall water-splitting reaction. 相似文献
73.
An Unprecedented Two‐Fold Nested Super‐Polyrotaxane: Sulfate‐Directed Hierarchical Polythreading Assembly of Uranyl Polyrotaxane Moieties
下载免费PDF全文
![点击此处可从《Chemistry (Weinheim an der Bergstrasse, Germany)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Dr. Lei Mei Dr. Qun‐yan Wu Dr. Li‐yong Yuan Dr. Lin Wang Shu‐wen An Zhen‐ni Xie Dr. Kong‐qiu Hu Prof. Zhi‐fang Chai Prof. Peter C. Burns Prof. Wei‐qun Shi 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(32):11329-11338
The hierarchical assembly of well‐organized submoieties could lead to more complicated superstructures with intriguing properties. We describe herein an unprecedented polyrotaxane polythreading framework containing a two‐fold nested super‐polyrotaxane substructure, which was synthesized through a uranyl‐directed hierarchical polythreading assembly of one‐dimensional polyrotaxane chains and two‐dimensional polyrotaxane networks. This special assembly mode actually affords a new way of supramolecular chemistry instead of covalently linked bulky stoppers to construct stable interlocked rotaxane moieties. An investigation of the synthesis condition shows that sulfate can assume a vital role in mediating the formation of different uranyl species, especially the unique trinuclear uranyl moiety [(UO2)3O(OH)2]2+, involving a notable bent [O=U=O] bond with a bond angle of 172.0(9)°. Detailed analysis of the coordination features, the thermal stability as well as a fluorescence, and electrochemical characterization demonstrate that the uniqueness of this super‐polyrotaxane structure is mainly closely related to the trinuclear uranyl moiety, which is confirmed by quantum chemical calculations. 相似文献
74.
75.
Ren Y Acuña UM Jiménez F García R Mejía M Chai H Gallucci JC Farnsworth NR Soejarto DD Carcache de Blanco EJ Kinghorn AD 《Tetrahedron》2012,68(12):2671-2678
Six new (1-6) and eight known germacranolide-type sesquiterpene lactones, along with several known phenylpropanol coumarates and methylated flavonoids, were isolated from the leaves of Piptocoma rufescens, collected in the Dominican Republic. The new compounds were identified by analysis of their spectroscopic data, with the molecular structure of 3 being established by single-crystal X-ray diffraction. The absolute configurations of the sesquiterpene lactones isolated were determined from their CD and NOESY NMR spectra, together with the analysis of Mosher ester reactions. Bioassay screening results showed the majority of the sesquiterpene lactones isolated (1-13) to be highly cytotoxic toward the HT-29 human colon cancer cell line, with the most potent compound being 15-deoxygoyazensolide (10, IC(50), 0.26 μM). In addition, several of the sesquiterpene lactones exhibited NF-κB (p65) inhibitory activity. 相似文献
76.
Chen Chen Xiangheng Niu Yan Chai Hongli Zhao Minbo Lan Yonggang Zhu Gang Wei 《Electroanalysis》2013,25(6):1446-1452
This work presents a disposable bismuth‐antimony film electrode fabricated on screen‐printed electrode (SPE) substrates for lead(II) determination. This bismuth‐antimony film screen‐printed electrode (Bi‐SbSPE) is simply prepared by simultaneously in situ depositing bismuth(III) and antimony(III) with analytes on the homemade SPE. The Bi‐SbSPE can provide an enhanced electrochemical stripping signal for lead(II) compared to bismuth film screen‐printed electrodes (BiSPE), antimony film screen‐printed electrodes (SbSPE) and bismuth‐antimony film glassy carbon electrodes (Bi‐SbGC). Under optimized conditions, the Bi‐SbSPE exhibits attractive linear responses towards lead(II) with a detection limit of 0.07 µg/L. The Bi‐SbSPE has been demonstrated successfully to detect lead in river water sample. 相似文献
77.
M. N. Chai 《International Journal of Polymer Analysis and Characterization》2013,18(4):280-286
Electrical impedance spectroscopy was used to measure the conductivity of solid polymer electrolytes. From the impedance study, the highest ionic conductivity of solid polymer electrolytes based on carboxyl methylcellulose as polymer host and oleic acid as the doping salt, prepared by the solution casting method at room temperature, σr.t, is 2.11 × 10?5 S cm?1 for the sample containing 20 wt.% of oleic acid. Transference number measurement was performed to correlate the diffusion phenomena to the conductivity behavior of carboxyl methylcellulose-oleic acid solid polymer electrolytes. From the transference number measurement study, the conduction species carrier of the cation (+) is higher than that of the anion (?). Thus, the results proved that the samples are proton-conducting solid polymer electrolytes. 相似文献
78.
Mengbo Zhou Li Song Feng Niu Kangying Shu Wenxiang Chai 《Acta Crystallographica. Section C, Structural Chemistry》2013,69(5):463-466
In the title CuII complex, [Cu(C19H14O3P)2(C3H7NO)(H2O)2], the molecule is bisected by a twofold axis relating the two 2‐(diphenylphosphoryl)benzoate (ODPPB) ligands. The asymmetric unit consists of a CuII metal centre on the symmetry axis, an ODPPB ligand, one water ligand and one dimethylformamide (DMF) ligand (disordered around the twofold axis). The CuII ion has fivefold coordination provided by two carboxylate O atoms from two ODPPB ligands, two O atoms from two coordinated water molecules and another O atom from a (disordered) DMF molecule, giving a CuO5 square‐pyramidal coordination geometry. The ODPPB ligand adopts a terminal monocoordinated mode with two free O atoms forming two strong intramolecular hydrogen bonds with the coordinated water molecules, which may play a key role in the stability of the molecular structure, as shown by the higher release temperature for the coordinated water molecules than for the coordinated DMF molecule. The optical absorption properties of powder samples of the title compound have also been studied. 相似文献
79.
Huachang Chen Dongying YuanYiya Li Mingjie DongZhihua Chai Juan KongGuoqi Fu 《Analytica chimica acta》2013
Surface imprinting over nanosized support materials is particularly suitable for protein templates, considering the problems with mass transfer limitation and low binding capacity. Previously we have demonstrated a strategy for surface protein imprinting over vinyl-modified silica nanopartiles with lysozyme as a model template by polymerization in high-dilution monomer solution to prevent macrogelation. Herein, the synthesis process was further studied toward enhancement of the imprinting performance by examining the effect of several synthesis conditions. Interestingly, the feed crosslinking degree was found to have a great impact on the thickness of the formed imprinting polymer layers and the recognition properties of the resulting imprinted materials. The imprinted particles with a crosslinking degree up to 50% showed the best imprinting effect. The imprinting factor achieved 2.89 and the specific binding reached 23.3 mg g−1, which are greatly increased compared to those of the lowly crosslinked imprinted materials reported previously. Moreover, the relatively high crosslinking degree led to no significant retarding of the binding kinetics to the imprinted particles, and the saturated adsorption was reached within 10 min. Therefore, this may be a promising method for protein imprinting. 相似文献
80.