全文获取类型
收费全文 | 776篇 |
免费 | 15篇 |
专业分类
化学 | 632篇 |
晶体学 | 4篇 |
力学 | 4篇 |
数学 | 36篇 |
物理学 | 115篇 |
出版年
2023年 | 5篇 |
2022年 | 7篇 |
2021年 | 25篇 |
2020年 | 19篇 |
2019年 | 27篇 |
2018年 | 36篇 |
2017年 | 28篇 |
2016年 | 19篇 |
2015年 | 19篇 |
2014年 | 23篇 |
2013年 | 60篇 |
2012年 | 23篇 |
2011年 | 47篇 |
2010年 | 40篇 |
2009年 | 32篇 |
2008年 | 40篇 |
2007年 | 54篇 |
2006年 | 40篇 |
2005年 | 38篇 |
2004年 | 35篇 |
2003年 | 24篇 |
2002年 | 28篇 |
2001年 | 16篇 |
2000年 | 9篇 |
1999年 | 13篇 |
1998年 | 7篇 |
1997年 | 4篇 |
1996年 | 11篇 |
1995年 | 6篇 |
1994年 | 2篇 |
1993年 | 6篇 |
1992年 | 6篇 |
1991年 | 3篇 |
1990年 | 4篇 |
1989年 | 2篇 |
1988年 | 5篇 |
1985年 | 2篇 |
1984年 | 4篇 |
1983年 | 1篇 |
1981年 | 1篇 |
1980年 | 3篇 |
1979年 | 1篇 |
1978年 | 3篇 |
1977年 | 2篇 |
1976年 | 1篇 |
1974年 | 2篇 |
1973年 | 1篇 |
1972年 | 2篇 |
1969年 | 1篇 |
1968年 | 1篇 |
排序方式: 共有791条查询结果,搜索用时 46 毫秒
81.
82.
83.
Nina Perkas Michael Shuster Galina Amirian Yuri Koltypin Aharon Gedanken 《Journal of polymer science. Part A, Polymer chemistry》2008,46(5):1719-1729
Silver nanoparticles were immobilized on the surface of polypropylene (PP) porous beads by an ultrasound‐assisted reduction method. The structure and properties of the silver–PP composite were characterized with XRD, TEM, HRSEM, EDX, XPS, and Raman spectroscopy. Water‐soluble polymers such as PEG, PVA, and PVP were used as stabilizing agents for preventing the agglomeration of the silver nanoparticles. With PVP, a homogeneous distribution of silver nanocrystals, 50 nm in size, on the PP surface was achieved. The mechanism proposed for the silver anchoring to the inert polymer accounts for a localized melting of the PP. The beads of the silver PP composite demonstrated good stability and high antibacterial activity. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 1719–1729, 2008 相似文献
84.
Sergey Miltsov Vladimir Karavan Alexandr Misharev Galina Starova Julian Alonso-Chamarro Mar Puyol 《Tetrahedron letters》2017,58(34):3353-3357
meso-Bromosubstituted indodicarbocyanine dyes produce dimeric molecules, together with the debrominated species, under acid catalysis. The relationship between the dimerization and hydrodebromination routes depends on the aryl substitution of the dyes. A possible reaction mechanism is also proposed. 相似文献
85.
Vadim Baigildin Galina Pankova Tatyana Evseeva Nikolay Lavrov Irina Shirokova Gleb Vaganov 《Journal of Dispersion Science and Technology》2017,38(11):1570-1577
The present article investigates the influence of dispersion medium on the aggregate stability of cross-linked poly-(methyl methacrylate) particles on the surface layer of which aliphatic amino groups are localized. It is shown that particle size depends on the ionic strength of dispersion medium. The research determines the optimal content of cross-linked agent, ethylene glycol dimetharylate that results in the formation of cationic particles being stable in saline. Particle modification is performed by bovine serum albumin and luminophore fluorescein 5(6)-isothiocyanate. Protein sorption is observed not to influence luminescent properties of the particles. It is also determined that due to the aggregate stability of particles obtained from 5?wt% of ethylene glycol dimethacrylate in saline, the monodispersity and the absence of inversion of zeta potential in wide pH range is retained, such particles may be considered as perspective carriers of biologically active substances. 相似文献
86.
Raman spectroscopy at 25 °C was performed to analyze speciation in quenched solutions after experiments on sodium tungstates
and sodium tungstate bronze dissolution at t=500 °C, p=1000 bar. The experiments were conducted under different oxidation-reduction conditions in sodium chloride solution media.
The spectra of the quenched solutions were different from those of the reference solutions of 0.02 mol⋅kg−1 W(VI) (H2O) in the pH range 2.3–7.2. Thermodynamic models were established and the fields of predominance of different isopolytungstate
species at 25–50 °C were determined. The experimental results of tungstate dissolution demonstrates that reduced tungstate
solutions may contain a significant amount of tungsten species with valence states lower than W(VI). 相似文献
87.
Krylova G Brioude A Ababou-Girard S Mrazek J Spanhel L 《Physical chemistry chemical physics : PCCP》2010,12(45):15101-15110
The additive free heteronucleation and nanocrystallization of ternary Zn(x)Ti(y)O(z) sols and coatings is presented. A proper adjustment of the Zn/Ti ratio in the sol allows the formation of elaborate superhydrophilic cubic spinel-like Zn(2)TiO(4), c-ZnTiO(3) or h-ZnTiO(3)-ilmentite/r-TiO(2)-rutile films. Their morphology and natural superhydrophilicity can be fine-tuned by the inclusion of 5% silica. This doping step delivers high dye intake capacities and water contact angle values below 3°. XPS analysis indicates that Zn and Si enrichment enables greater surface hydroxylation and thus improved water wetting behaviour. The transparent h-ZnTiO(3)-ilmenite/r-TiO(2) nanocomposite coatings deposited on glass and Si-wafers show a remarkable activity in the photomineralization of fatty-acids. 相似文献
88.
Agata L. Starosta Viktoriya V. Karpenko Anna V. Shishkina Aleksandra Mikolajka Natalia V. Sumbatyan Frank Schluenzen Galina A. Korshunova Alexey A. Bogdanov Daniel N. Wilson 《Chemistry & biology》2010,17(5):504-514
Highlights? Macrolides exhibit nascent polypeptide chain–dependent inhibition ? Peptides can form specific interactions with the ribosomal tunnel ? A covalent bond between tylosin and the ribosome is necessary for inhibitory activity 相似文献
89.
Renat R. Nazmutdinov Tamara T. Zinkicheva Sergey Yu. Vassiliev Dmitri V. Glukhov Galina A. Tsirlina Michael Probst 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2010,75(4):1244-1252
The structure of sodium cryolite melts was studied using Raman spectroscopy and quantum chemical calculations performed at the density functional theory level. The existence of bridged forms in the melts was argued first from the analysis of experimental Raman spectra. In the quantum chemical modelling emphasis was put on the construction of potential energy surfaces describing the formation/dissociation of certain complex species. Effects of the ionic environment were found to play a crucial role in the energetics of model processes. The structure of the simplest possible polymeric forms involving two Al centres linked through F atoms (“dimers”) was thoroughly investigated. The calculated equilibrium constants and model Raman spectra yield additional evidence in favour of the dimers. This agrees with a self-consistent analysis of a series of Raman spectra for a wide range of the melt composition. 相似文献
90.
Zhiyong Li Jonathan Crook Galina Andreeva 《The Journal of the Operational Research Society》2014,65(3):466-479
Bankruptcy prediction is a key part in corporate credit risk management. Traditional bankruptcy prediction models employ financial ratios or market prices to predict bankruptcy or financial distress prior to its occurrence. We investigate the predictive accuracy of corporate efficiency measures along with standard financial ratios in predicting corporate distress in Chinese companies. Data Envelopment Analysis (DEA) is used to measure corporate efficiency. In contrast to previous applications of DEA in credit risk modelling where it was used to generate a single efficiency—Technical Efficiency (TE), we assume Variable Returns to Scale, and decompose TE into Pure Technical Efficiency and Scale Efficiency. These measures are introduced into Logistic Regression to predict the probability of distress, along with the level of Returns to Scale. Effects of efficiency variables are allowed to vary across industries through the use of interaction terms, while the financial ratios are assumed to have the same effects across all sectors. The results show that the predictive power of the model is improved by this corporate efficiency information. 相似文献