全文获取类型
收费全文 | 736篇 |
免费 | 42篇 |
国内免费 | 11篇 |
专业分类
化学 | 545篇 |
晶体学 | 3篇 |
力学 | 34篇 |
数学 | 72篇 |
物理学 | 135篇 |
出版年
2023年 | 5篇 |
2022年 | 14篇 |
2021年 | 25篇 |
2020年 | 24篇 |
2019年 | 21篇 |
2018年 | 39篇 |
2017年 | 19篇 |
2016年 | 44篇 |
2015年 | 29篇 |
2014年 | 38篇 |
2013年 | 71篇 |
2012年 | 84篇 |
2011年 | 81篇 |
2010年 | 53篇 |
2009年 | 44篇 |
2008年 | 36篇 |
2007年 | 35篇 |
2006年 | 27篇 |
2005年 | 21篇 |
2004年 | 23篇 |
2003年 | 16篇 |
2002年 | 14篇 |
2001年 | 6篇 |
2000年 | 4篇 |
1999年 | 1篇 |
1998年 | 2篇 |
1997年 | 3篇 |
1996年 | 3篇 |
1994年 | 1篇 |
1990年 | 1篇 |
1987年 | 1篇 |
1985年 | 1篇 |
1971年 | 1篇 |
1970年 | 1篇 |
1932年 | 1篇 |
排序方式: 共有789条查询结果,搜索用时 15 毫秒
61.
62.
G. Rezaei Behbehani 《中国化学快报》2009,20(6)
The interaction of CuC12 to the first 16 residues of the Alzbeimer's amyliod β peptide, Aβ(1-16) was studied by isothermal titration calorimetry at pH 7.2 and 37 ℃ in aqueous solution. 相似文献
63.
Daniel C. Steigerwald Bardia Soltanzadeh Aritra Sarkar Cecilia C. Morgenstern Richard J. Staples Babak Borhan 《Chemical science》2021,12(5):1834
Intermolecular asymmetric haloamination reactions are challenging due to the inherently high halenium affinity (HalA) of the nitrogen atom, which often leads to N-halogenated products as a kinetic trap. To circumvent this issue, acetonitrile, possessing a low HalA, was used as the nucleophile in the catalytic asymmetric Ritter-type chloroamidation of allyl-amides. This method is compatible with Z and E alkenes with both alkyl and aromatic substitution. Mild acidic workup reveals the 1,2-chloroamide products with enantiomeric excess greater than 95% for many examples. We also report the successful use of the sulfonamide chlorenium reagent dichloramine-T in this chlorenium-initiated catalytic asymmetric Ritter-type reaction. Facile modifications lead to chiral imidazoline, guanidine, and orthogonally protected 1,2,3 chiral tri-amines.Intermolecular haloamination reactions are challenging due to the high halenium affinity of the nitrogen atom. This is circumvented by using acetonitrile as an attenuated nucleophile, resulting in an enantioselective halo-Ritter reaction. 相似文献
64.
Abedinifar Fahimeh Babazadeh Rezaei Elham Biglar Mahmood Larijani Bagher Hamedifar Halleh Ansari Samira Mahdavi Mohammad 《Molecular diversity》2021,25(4):2571-2604
Molecular Diversity - Thiophene-based analogs have been fascinated by a growing number of scientists as a potential class of biologically active compounds. Furthermore, they play a vital role for... 相似文献
65.
International Journal of Theoretical Physics - In this paper, we present the annihilation and creation operators for a moving scalar massive particle on 1 + 1-de Sitter space. This presentation is... 相似文献
66.
A molecular-level simulation route is proposed to compute the isentropic thermodynamic properties in a fluid system by Monte Carlo simulation at fixed entropy. The method involves computation of the pressure response of a system to an infinitesimal change in system density by introduction of a single molecule, while retaining the system volume as well as the absolute molar entropy. The probability for accepting a change in temperature during the Monte Carlo moves was weighted against the argument proposed by Smith et al. [W.R. Smith, M. Lísal, I. Nezbeda, Chem. Phys. Lett. 426 (2006) 436–440]. Application to fluid argon has confirmed superior accuracy for the technique within the gas state to yield results within 1.2% of the measured values for the range of thermodynamic conditions investigated. 相似文献
67.
H. Mansouri‐Torshizi M. Saeidifar G. R. Rezaei‐Behbehani A. Divsalar A. A. Saboury 《中国化学会会志》2010,57(6):1299-1308
Interaction between ethylenediamine 8‐hydroxyquinolinato palladium(II) chloride and calf thymus DNA (CT‐DNA) in aqueous solution were studied by UV‐Visible absorption, fluorescence spectroscopic techniques and gel chromatography at temperatures of 300 K and 310 K. The complex bound strongly and intercalatively to the CT‐DNA. The results of the cytotoxicity assay of the Pd(II) complex on the leukemia cell line, K562 indicated lower cytotoxicity than cisplatin. The Pd(II) complex is considered an agent with potential antitumor activity. The calculation of several binding and thermodynamic parameters of the inclusion Pd(II) complex with CT‐DNA may provide deeper insights into the mechanism of action of these types of complexes with nucleic acids. 相似文献
68.
Xiao Zhou Yali Lu Wenjing Wang Babak Borhan Gavin E. Reid 《Journal of the American Society for Mass Spectrometry》2010,21(8):1339-1351
Protein surface accessible residues play an important role in protein folding, protein-protein interactions and protein-ligand
binding. However, a common problem associated with the use of selective chemical labeling methods for mapping protein solvent
accessible residues is that when a complicated peptide mixture resulting from a large protein or protein complex is analyzed,
the modified peptides may be difficult to identify and characterize amongst the largely unmodified peptide population (i.e.,
the ‘needle in a haystack’ problem). To address this challenge, we describe here the development of a strategy involving the
synthesis and application of a novel ‘fixed charge’ sulfonium ion containing lysine-specific protein modification reagent,
S,S′-dimethylthiobutanoylhydroxysuccinimide ester (DMBNHS), coupled with capillary HPLC-ESI-MS, automated CID-MS/MS, and data-dependant
neutral loss mode MS3 in an ion trap mass spectrometer, to map the surface accessible lysine residues in a small model protein, cellular retinoic
acid binding protein II (CRABP II). After reaction with different reagent:protein ratios and digestion with Glu-C, modified
peptides are selectively identified and the number of modifications within each peptide are determined by CID-MS/MS, via the
exclusive neutral loss(es) of dimethylsulfide, independently of the amino acid composition and precursor ion charge state
(i.e., proton mobility) of the peptide. The observation of these characteristic neutral losses are then used to automatically
‘trigger’ the acquisition of an MS3 spectrum to allow the peptide sequence and the site(s) of modification to be characterized. Using this approach, the experimentally
determined relative solvent accessibilities of the lysine residues were found to show good agreement with the known solution
structure of CRABP II. 相似文献
69.
Adsorption of Triton X-100 (TX-100) on silica gel has been studied as a function of temperature (308–328 K) and composition
for mixtures of water with ethanol or t-butanol. The adsorption capacity of silica gel for TX-100 decreases with increase
in alcohol content. Adsorption isotherms of TX-100 on silica gel are four-region and were analyzed using the ARIAN (adsorption
isotherm regional analysis) model. Data in regions 2, 3 and 4 were fitted to the Temkin, bilayer and reverse desorption isotherms,
respectively. The results show that adsorption of TX-100 on silica gel in water and alcohol-water binary mixtures occurs mainly
through formation of monolayer surface aggregates or low bilayer coverage.
相似文献
70.
We show that it is possible to use hard-Pomeron behavior to the gluon distribution and singlet structure function at low x. We derive a second-order independent differential equation for the gluon distribution and the singlet structure function.
In this approach, both singlet quarks and gluons have the same high-energy behavior at small x. These equations are derived from the next-to-leading order DGLAP evolution equations. All results can be consistently described
in the framework of perturbative QCD, which shows an increase of gluon distribution and singlet structure functions as x decreases. 相似文献