全文获取类型
收费全文 | 945篇 |
免费 | 33篇 |
国内免费 | 3篇 |
专业分类
化学 | 575篇 |
晶体学 | 6篇 |
力学 | 22篇 |
数学 | 90篇 |
物理学 | 288篇 |
出版年
2023年 | 3篇 |
2022年 | 13篇 |
2021年 | 20篇 |
2020年 | 16篇 |
2019年 | 18篇 |
2018年 | 17篇 |
2017年 | 19篇 |
2016年 | 34篇 |
2015年 | 24篇 |
2014年 | 24篇 |
2013年 | 47篇 |
2012年 | 52篇 |
2011年 | 66篇 |
2010年 | 40篇 |
2009年 | 37篇 |
2008年 | 48篇 |
2007年 | 54篇 |
2006年 | 36篇 |
2005年 | 34篇 |
2004年 | 40篇 |
2003年 | 31篇 |
2002年 | 36篇 |
2001年 | 14篇 |
2000年 | 27篇 |
1999年 | 6篇 |
1998年 | 6篇 |
1997年 | 12篇 |
1996年 | 12篇 |
1995年 | 8篇 |
1994年 | 12篇 |
1993年 | 14篇 |
1992年 | 15篇 |
1991年 | 14篇 |
1990年 | 20篇 |
1989年 | 11篇 |
1988年 | 16篇 |
1987年 | 10篇 |
1986年 | 11篇 |
1985年 | 7篇 |
1984年 | 3篇 |
1983年 | 6篇 |
1982年 | 11篇 |
1981年 | 6篇 |
1980年 | 3篇 |
1979年 | 5篇 |
1978年 | 3篇 |
1977年 | 4篇 |
1976年 | 4篇 |
1973年 | 2篇 |
1972年 | 2篇 |
排序方式: 共有981条查询结果,搜索用时 437 毫秒
141.
142.
John S. C. Kearney Miglė Graužinytė Dr. Dean Smith Daniel Sneed Christian Childs Jasmine Hinton Dr. Changyong Park Dr. Jesse S. Smith Dr. Eunja Kim Samuel D. S. Fitch Prof. Dr. Andrew L. Hector Prof. Dr. Chris J. Pickard Dr. José A. Flores‐Livas Prof. Dr. Ashkan Salamat 《Angewandte Chemie (International ed. in English)》2018,57(36):11623-11628
The application of pressure allows systematic tuning of the charge density of a material cleanly, that is, without changes to the chemical composition via dopants, and exploratory high‐pressure experiments can inform the design of bulk syntheses of materials that benefit from their properties under compression. The electronic and structural response of semiconducting tin nitride Sn3N4 under compression is now reported. A continuous opening of the optical band gap was observed from 1.3 eV to 3.0 eV over a range of 100 GPa, a 540 nm blue‐shift spanning the entire visible spectrum. The pressure‐mediated band gap opening is general to this material across numerous high‐density polymorphs, implicating the predominant ionic bonding in the material as the cause. The rate of decompression to ambient conditions permits access to recoverable metastable states with varying band gaps energies, opening the possibility of pressure‐tuneable electronic properties for future applications. 相似文献
143.
Three‐Dimensional Branched and Faceted Gold–Ruthenium Nanoparticles: Using Nanostructure to Improve Stability in Oxygen Evolution Electrocatalysis 下载免费PDF全文
Dr. Lucy Gloag Dr. Tania M. Benedetti Dr. Soshan Cheong Dr. Yibing Li Dr. Xuan‐Hao Chan Prof. Lise‐Marie Lacroix Prof. Shery L. Y. Chang Dr. Raul Arenal Dr. Ileana Florea Dr. Hector Barron Dr. Amanda S. Barnard Dr. Anna M. Henning Prof. Chuan Zhao Prof. Wolfgang Schuhmann Prof. J. Justin Gooding Prof. Richard D. Tilley 《Angewandte Chemie (International ed. in English)》2018,57(32):10241-10245
Achieving stability with highly active Ru nanoparticles for electrocatalysis is a major challenge for the oxygen evolution reaction. As improved stability of Ru catalysts has been shown for bulk surfaces with low‐index facets, there is an opportunity to incorporate these stable facets into Ru nanoparticles. Now, a new solution synthesis is presented in which hexagonal close‐packed structured Ru is grown on Au to form nanoparticles with 3D branches. Exposing low‐index facets on these 3D branches creates stable reaction kinetics to achieve high activity and the highest stability observed for Ru nanoparticle oxygen evolution reaction catalysts. These design principles provide a synthetic strategy to achieve stable and active electrocatalysts. 相似文献
144.
Frontispiece: Docking Strategy To Construct Thermostable,Single‐Crystalline,Hydrogen‐Bonded Organic Framework with High Surface Area 下载免费PDF全文
145.
Brandaleze Elena Bazán Vanesa Orozco Ivana Valentini Marcelo Gomez Giuliana 《Journal of Thermal Analysis and Calorimetry》2018,133(1):435-441
Journal of Thermal Analysis and Calorimetry - Rhenium production from copper and molybdenum sulphides involves the use of a pyrometallurgical process. In traditional pyrometallurgy processes, gases... 相似文献
146.
Hector Ortiz-Ibarra Refugio Torres-Vitela Sergio Gómez-Salazar Norberto Casillas Carlos Ponce de León Frank C. Walsh 《Journal of Solid State Electrochemistry》2018,22(3):749-759
The natural antibacterial activity of silver represents an alternative to deal with the ever increasing pathogenic breakouts related with contaminated water resources. In this study, silver was deposited on the surface of activated carbon (AC) particles via pulsed electrodeposition (PED) employing an electrochemical reactor operating at fixed and fluidized bed regimes. Silver-coated activated carbon (Ag/AC) particles were prepared at different current pulse frequency values. Antimicrobial properties of the produced material were tested against two well-known foodborne pathogens, i.e., Escherichia coli O157:H7 and Salmonella typhimurium. The results demonstrate a strong influence of the applied current pulse frequency on both the bactericidal efficiency and the specific surface of silver deposited on the activated carbon. Antibacterial results demonstrate up to eight orders of magnitude decrease in the CFU cm?3 (colony-forming units per cm3) against both microorganisms in just 20 min contact time. Additional chronoamperometry transient data were fitted to the Scharifker-Hills nucleation model for the electrodeposition of silver at a rotating disk electrode, revealing an instantaneous nucleation growth processes. The Ag/AC particles were characterized by field emission scanning electron microscopy (FE-SEM), specific surface area (SBET), Raman spectroscopy, energy dispersive X-ray spectroscopy (EDS), and X-ray diffraction (XRD), demonstrating the existence of crystalline phase formation of a preferential (200) plane growth with silver and silver oxide being present. 相似文献
147.
Jerry Fields Xiang Ouyang Steven R. Herron Katherine A. Kantardjieff Ali Jabalameli Frank A. Gomez 《Journal of chemical crystallography》2007,37(1):55-62
The synthesis and molecular structure of the novel 1-[ferrocenyl(hydroxy)methyl]-1,7-dicarba-closo-dodecaborane (1) is described. Compound 1 was synthesized from reaction of m-carborane and ferrocene carboxaldehyde using n-butyllithium (n-BuLi) or tetrabutylammonium fluoride (TBAF) in THF in 45% and 36% yield, respectively. Compound 1 consists of a ferrocene molecule tethered to m-carborane through a methylhydroxy bridge. The crystal structure of 1 was determined by single crystal X-ray diffraction analysis. Crystal data: 1 [Fe(C5H5)(C5H4-CH2O-1,7-C2B10H12)], formula weight = 359.17, crystallized in orthorhombic system, space group Pna2
1
with a=19.698(4) ?, b=10.709(2) ?, c=8.520(2) ?, and V=1797.3(7) ?3 and Z=4. Refined to R
1=0.043 for 4124 observed reflections with I/σ>2σ(I). The compound was crystallized as racemic twins in a ratio of 73(2)/27(2). The unsubstituted Cp ring was disordered and
modeled as two conformations in a 53(3)/47(3) ratio. Intermolecular hydrogen bonding was observed from the hydrogen of the
meta-carbon on the carborane cluster towards the hydroxyl oxygen. 相似文献
148.
A critical review of recent developments in the use of chemometric experimental design based optimization techniques in capillary
electrophoresis applications is presented. Current advances have led to enhanced separation capabilities of a wide range of
analytes in such areas as biological, environmental, food technology, pharmaceutical, and medical analysis. Significant developments
in design, detection methodology and applications from the last 5 years (2002–2007) are reported. Furthermore, future perspectives
in the use of chemometric methodology in capillary electrophoresis are considered. 相似文献
149.
Marine derived polysaccharides for biomedical applications: chemical modification approaches 总被引:1,自引:0,他引:1
Polysaccharide-based biomaterials are an emerging class in several biomedical fields such as tissue regeneration, particularly for cartilage, drug delivery devices and gelentrapment systems for the immobilization of cells. Important properties of the polysaccharides include controllable biological activity, biodegradability, and their ability to form hydrogels. Most of the polysaccharides used derive from natural sources; particularly, alginate and chitin, two polysaccharides which have an extensive history of use in medicine, pharmacy and basic sciences, and can be easily extracted from marine plants (algae kelp) and crab shells, respectively. The recent rediscovery of poly-saccharidebased materials is also attributable to new synthetic routes for their chemical modification, with the aim of promoting new biological activities and/or to modify the final properties of the biomaterials for specific purposes. These synthetic strategies also involve the combination of polysaccharides with other polymers. A review of the more recent research in the field of chemical modification of alginate, chitin and its derivative chitosan is presented. Moreover, we report as case studies the results of our recent work concerning various different approaches and applications of polysaccharide-based biomaterials, such as the realization of novel composites based on calcium sulphate blended with alginate and with a chemically modified chitosan, the synthesis of novel alginate-poly(ethylene glycol) copolymers and the development of a family of materials based on alginate and acrylic polymers of potential interest as drug delivery systems. 相似文献
150.
A novel solid-phase synthesis of tetrasubstituted 2-imino-1,3-thiazolines using a functionalizing cleavage strategy is described. The synthetic route utilized the ambident reactivity of a dithiocarbamate functionality to synthesize the key resin-bound electrophilic thiazolium intermediate. The desired products were efficiently obtained in high purity by the reaction of various amines with the thiazolium salt. 相似文献