全文获取类型
收费全文 | 842篇 |
免费 | 97篇 |
国内免费 | 4篇 |
专业分类
化学 | 734篇 |
晶体学 | 2篇 |
力学 | 16篇 |
数学 | 83篇 |
物理学 | 108篇 |
出版年
2023年 | 31篇 |
2022年 | 26篇 |
2021年 | 49篇 |
2020年 | 71篇 |
2019年 | 81篇 |
2018年 | 30篇 |
2017年 | 19篇 |
2016年 | 75篇 |
2015年 | 54篇 |
2014年 | 36篇 |
2013年 | 66篇 |
2012年 | 48篇 |
2011年 | 61篇 |
2010年 | 26篇 |
2009年 | 16篇 |
2008年 | 34篇 |
2007年 | 24篇 |
2006年 | 28篇 |
2005年 | 26篇 |
2004年 | 15篇 |
2003年 | 12篇 |
2002年 | 10篇 |
2001年 | 8篇 |
2000年 | 8篇 |
1999年 | 6篇 |
1997年 | 3篇 |
1996年 | 8篇 |
1995年 | 5篇 |
1994年 | 4篇 |
1992年 | 4篇 |
1991年 | 5篇 |
1988年 | 2篇 |
1985年 | 4篇 |
1984年 | 6篇 |
1982年 | 2篇 |
1979年 | 2篇 |
1978年 | 3篇 |
1977年 | 3篇 |
1976年 | 2篇 |
1975年 | 3篇 |
1973年 | 2篇 |
1934年 | 2篇 |
1932年 | 2篇 |
1931年 | 2篇 |
1930年 | 2篇 |
1929年 | 1篇 |
1928年 | 2篇 |
1919年 | 1篇 |
1913年 | 1篇 |
1894年 | 1篇 |
排序方式: 共有943条查询结果,搜索用时 31 毫秒
91.
Lukas Stolzer Antonina Vigovskaya Prof. Christopher Barner‐Kowollik Dr. Ljiljana Fruk 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(41):14309-14313
A photochemical approach based on nitrile imine‐mediated tetrazole‐ene cycloaddition is introduced to functionalize gold nanorods with biomolecules. For this purpose, a bifunctional, photoreactive linker containing thioctic acid as the Au anchoring group and a tetrazole moiety for the light‐induced reaction with maleimide‐capped DNA was prepared. The tetrazole‐based reaction on the nanoparticles’ surface results in a fluorescent pyrazoline product allowing for the spectroscopic monitoring of the reaction. This first example of nitrile imine‐mediated tetrazole‐ene cycloaddition (NITEC)‐mediated biofunctionalization of Au nanorods paves the way for the attachment of sensitive biomolecules, such as antibodies and other proteins, under mild conditions and expands the toolbox for the tailoring of nanomaterials. 相似文献
92.
Very Facile Polarity Umpolung and Noncovalent Functionalization of Inorganic Nanoparticles: A Tool Kit for Supramolecular Materials Chemistry
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)
Lukas Zeininger Stefanie Petzi Jörg Schönamsgruber Luis Portilla Prof. Dr. Marcus Halik Prof. Dr. Andreas Hirsch 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(40):14030-14035
The facile assembly of shell‐by‐shell (SbS)‐coated nanoparticles [TiO2?PAC16]@shell 1 – 7 (PAC16=hexadecylphosphonic acid), which are soluble in water and can be isolated as stable solids, is reported. In these functional architectures, an umpolung of dispersibility (organic apolar versus water) was accomplished by the noncovalent binding of ligands 1 – 7 to titania nanoparticles [TiO2?PAC16] containing a first covalent coating with PAC16. Ligands 1 – 7 are amphiphilic and form the outer second shell of [TiO2?PAC16]@shell 1 – 7 . The tailor‐designed dendritic building blocks 3 – 5 contain negative and positive charges in the same molecule, and ligands 6 and 7 contain a perylenetetracarboxylic acid dimide (PDI) core ( 6 / 7 ) as a photoactive reporter component. In the redox and photoactive system [TiO2?PAC16]@shell 7 , electronic communication between the inorganic core to the PDI ligands was observed. 相似文献
93.
The characteristics of a manufacturing product are influenced by a variety of different factors, such as the material properties of the base product. The prediction of properties that give optimal results in metal forming applications is a complex task but of high interest for the manufacturer. To realize such a prediction scheme, the process chain is split up into individual process steps and for each of them an inverse modeling is required. The specific aim of this work is to present an approach for the inverse problem formulation of a process step and to solve it using methods of machine learning. Moreover, the challenges that often arise due to the ill-posed nature of inverse problems will be discussed. The main focus is on the crystallographic texture of metals, which strongly affects the deformation behavior during a process step and highly influences the characteristics of the final product. (© 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
94.
In this short note, we give a characterization of domains satisfying Serre’s condition (R1) in terms of their canonical modules. In the special case of toric rings, this generalizes a result of the second author [9] where the normality is described in terms of the “shape” of the canonical module. 相似文献
95.
Susan Torabi Lukas Hammerschmidt Elena Voloshina Beate Paulus 《International journal of quantum chemistry》2014,114(14):943-951
The performance of wavefunction‐based correlation methods in theoretical solid‐state chemistry depends on reliable Hartree–Fock (HF) results for infinitly extended systems. Therefore, we optimized basis sets of valence‐triple‐ζ quality based on HF calculations for the periodic system of group‐12‐metal difluorides. Scalar‐relativistic effects were included in the case of the metal‐ions by applying small‐core pseudopotentials. To assess the quality of the proposed basis sets, the structural parameters, bulk moduli as well as cohesive and lattice energies of the systems were evaluated at the HF and the density functional theory levels. In addition to these two mean‐field approaches and to assess further employment of our basis sets to wavefunction‐based correlation methods we performed periodic local MP2 computations. Finally, the possibilities of pressure induced structural phase transitions occurring in the ZnF2, CdF2, and HgF2 were investigated. © 2014 Wiley Periodicals, Inc. 相似文献
96.
Structural stability is an important issue to ensure the safety of thin walled structures. Shell structures are considered in context of linear and non-linear buckling. The design sensitivity analysis with respect to modifications in shape is motivated. Analytically derived gradient information is employed for shape optimisation purposes using solid shells. (© 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
97.
98.
99.
Arndt M Salih KS Fromm A Goossen LJ Menges F Niedner-Schatteburg G 《Journal of the American Chemical Society》2011,133(19):7428-7449
The ruthenium-catalyzed hydroamidation of terminal alkynes has evolved to become a broadly applicable tool for the synthesis of enamides and enimides. Depending on the catalyst system employed, the reaction leads chemo-, regio-, and stereoselectively to a single diastereoisomer. Herein, we present a comprehensive mechanistic study of the ruthenium-catalyzed hydroamidation of terminal alkynes, which includes deuterium-labeling, in situ IR, in situ NMR, and in situ ESI-MS experiments complemented by computational studies. The results support the involvement of ruthenium-hydride and ruthenium-vinylidene species as the key intermediates. They are best explained by a reaction pathway that consists of an oxidative addition of the amide, followed by insertion of a π-coordinated alkyne into a ruthenium-hydride bond, rearrangement to a vinylidene species, nucleophilic attack of the amide, and finally reductive elimination of the product. 相似文献
100.
Boeck F Kribber T Xiao L Hintermann L 《Journal of the American Chemical Society》2011,133(21):8138-8141
The catalytic activity of [CpRu(L)(2)(MeCN)]PF(6) (L = 2-diphenylphosphinopyridine with bulky groups at C-6) for anti-Markovnikov hydration of terminal alkynes to aldehydes is retained when one heterocyclic ligand L is replaced by L' = PPh(3). Equal amounts of CpRuCl(PPh(3))(2) (1) and phosphane L in acetone solution equilibrate to a mixture of 1, CpRuCl(L)(PPh(3)) (2), and CpRuCl(L)(2) (3), which acts as highly active in situ catalyst for preparative anti-Markovnikov hydration of alkynes in water-rich media (2 mol % [Ru], 60 °C, 3-18 h in 4:1 (v/v) acetone/water). Reactions were completed in <15 min at 160 °C. 相似文献