全文获取类型
收费全文 | 91638篇 |
免费 | 1052篇 |
国内免费 | 518篇 |
专业分类
化学 | 33101篇 |
晶体学 | 829篇 |
力学 | 7008篇 |
综合类 | 1篇 |
数学 | 34581篇 |
物理学 | 17688篇 |
出版年
2023年 | 135篇 |
2022年 | 113篇 |
2021年 | 307篇 |
2020年 | 419篇 |
2019年 | 496篇 |
2018年 | 10713篇 |
2017年 | 10433篇 |
2016年 | 6564篇 |
2015年 | 1385篇 |
2014年 | 826篇 |
2013年 | 1207篇 |
2012年 | 4791篇 |
2011年 | 11641篇 |
2010年 | 6248篇 |
2009年 | 6547篇 |
2008年 | 7417篇 |
2007年 | 9476篇 |
2006年 | 1032篇 |
2005年 | 2044篇 |
2004年 | 2101篇 |
2003年 | 2385篇 |
2002年 | 1355篇 |
2001年 | 421篇 |
2000年 | 407篇 |
1999年 | 277篇 |
1998年 | 302篇 |
1997年 | 288篇 |
1996年 | 336篇 |
1995年 | 250篇 |
1994年 | 175篇 |
1993年 | 186篇 |
1992年 | 131篇 |
1991年 | 139篇 |
1990年 | 113篇 |
1989年 | 97篇 |
1988年 | 104篇 |
1987年 | 103篇 |
1986年 | 102篇 |
1985年 | 113篇 |
1984年 | 99篇 |
1983年 | 70篇 |
1982年 | 99篇 |
1981年 | 85篇 |
1980年 | 88篇 |
1979年 | 84篇 |
1978年 | 78篇 |
1977年 | 59篇 |
1976年 | 63篇 |
1973年 | 54篇 |
1909年 | 46篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
We describe the static charge susceptibility and correlation function of the charge density in the twodimensional t-J-V model based on the method of equations of motion for the relaxation functions of the Hubbard operators. We obtain the dependence of the susceptibility and correlation function on the hole concentration and temperature. Charge density waves can develop if the intersite Coulomb interaction is sufficiently strong. 相似文献
102.
103.
104.
105.
Benedict Vasco Normenyo Florian Luca Alain Togbé 《Periodica Mathematica Hungarica》2018,77(2):318-328
In this paper, all base 10 repdigits expressible as sums of three Pell numbers are found. 相似文献
106.
Myriam Drouin Dr. Parvesh Wadhwani Dr. Stephan L. Grage Dr. Jochen Bürck Dr. Johannes Reichert Sébastien Tremblay Marie Sabine Mayer Christian Diel Alexander Staub Prof. Jean-François Paquin Prof. Dr. Anne S. Ulrich 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(7):1511-1517
Solid-state 19F NMR is a powerful method to study the interactions of biologically active peptides with membranes. So far, in labelled peptides, the 19F-reporter group has always been installed on the side chain of an amino acid. Given the fact that monofluoroalkenes are non-hydrolyzable peptide bond mimics, we have synthesized a monofluoroalkene-based dipeptide isostere, Val-Ψ[(Z)-CF=CH]-Gly, and inserted it in the sequence of two well-studied antimicrobial peptides: PGLa and (KIGAKI)3 are representatives of an α-helix and a β-sheet. The conformations and biological activities of these labeled peptides were studied to assess the suitability of monofluoroalkenes for 19F NMR structure analysis. 相似文献
107.
108.
Dr. Thais F. Abelha Dr. Graeme Morris Dr. Sandro M. Lima Dr. Luis H. C. Andrade Dr. Andrew J. McLean Prof. Cameron Alexander Dr. Jesus Calvo-Castro Dr. Callum J. McHugh 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(14):3173-3180
Development of novel bioimaging materials that exhibit organelle specific accumulation continues to be at the forefront of research interests and efforts. Among the various subcellular organelles, mitochondria, which are found in the cytoplasm of eukaryotic cells, are of particular interest in relation to their vital function. To date, most molecular probes that target mitochondria utilise delocalised lipophilic cations such as triphenylphosphonium and pyridinium. However, the use of such charged motifs is known to be detrimental to the working function of the mitochondrial transmembrane potential and there remains a strong case for development of neutral mitochondrial fluorescent probes. Herein, we demonstrate for the first time the exploitation of diketopyrrolopyrrole-based chemistries for the realisation of a neutral fluorescent probe that exhibits organelle specific accumulation within the mitochondria at the nanomolar level. The synthesised probe, which bears a neutral triphenylphosphine oxide moiety, exhibits a large Stokes shift and high fluorescence quantum yield in water, both highly sought-after properties in the development of bioimaging agents. In vitro studies reveal no interference with cell metabolism when tested for the human MCF7 breast cancer cell and nanomolar subcellular organelle colocalisation with commercially available mitochondrial staining agent Mitotracker Red. In light of its novelty, neutral structure and the preferential accumulation at nanomolar concentrations we anticipate this work to be of significant interest for the increasingly larger community devoted to the realisation of neutral mitochondrial selective systems and more widely to those engaged in the rational development of superior organic architectures in the biological field. 相似文献
109.
Dr. Konstantin I. Galkin Bogdan Ya. Karlinskii Dr. Alexander Yu. Kostyukovich Dr. Evgeniy G. Gordeev Prof. Dr. Valentine P. Ananikov 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(39):8567-8571
This work reveals ambident nucleophilic reactivity of imidazolium cations towards carbonyl compounds at the C2 or C4 carbene centers depending on the steric properties of the substrates and reaction conditions. Such an adaptive behavior indicates the dynamic nature of organocatalysis proceeding via a covalent interaction of imidazolium carbenes with carbonyl substrates and can be explained by generation of the H-bonded ditopic carbanionic carbenes. 相似文献
110.
Daniel Townsend Prof. Dr. Kenneth Shankland Dr. Alex Weymouth-Wilson Dr. Zofia Komsta Dr. Tim Evans Dr. Alexander J. A. Cobb 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(16):3504-3508
A highly enantioselective, organocatalytic, and scalable synthesis of a very unusual cis-decalin-cis-hydrindane tricyclic diterpenoid system has been achieved. Despite the prevalent pharmacological space that the related trans,trans and trans,cis-systems occupy, there have been no reports of an asymmetric synthesis of the cis,cis systems in the literature until now. We demonstrate the flexibility of our approach not only through access to a diverse range of products, all of which are attained in exceptionally high selectivities, but also by showing their easy conversion to the corresponding trans,cis-system and other derivatives. 相似文献