全文获取类型
收费全文 | 411篇 |
免费 | 15篇 |
专业分类
化学 | 322篇 |
晶体学 | 1篇 |
力学 | 1篇 |
数学 | 41篇 |
物理学 | 61篇 |
出版年
2023年 | 6篇 |
2022年 | 19篇 |
2021年 | 15篇 |
2020年 | 11篇 |
2019年 | 21篇 |
2018年 | 19篇 |
2017年 | 20篇 |
2016年 | 24篇 |
2015年 | 16篇 |
2014年 | 25篇 |
2013年 | 36篇 |
2012年 | 27篇 |
2011年 | 35篇 |
2010年 | 18篇 |
2009年 | 11篇 |
2008年 | 15篇 |
2007年 | 29篇 |
2006年 | 14篇 |
2005年 | 19篇 |
2004年 | 13篇 |
2003年 | 11篇 |
2002年 | 10篇 |
2001年 | 2篇 |
2000年 | 3篇 |
1998年 | 3篇 |
1997年 | 1篇 |
1991年 | 2篇 |
1979年 | 1篇 |
排序方式: 共有426条查询结果,搜索用时 15 毫秒
31.
The hydrozirconation of alkynes with zirconocene hydrochloride and the dimethylzinc-mediated addition of alkenylzirconocenes to diphenylphosphinoyl imines can be greatly accelerated with microwave irradiation, resulting in a convenient and rapid one-pot process for the preparation of synthetically useful allylic amines. 相似文献
32.
Vujasinović I Veljković J Mlinarić-Majerski K 《The Journal of organic chemistry》2004,69(24):8550-8553
The preparation of new tin templates, stannathianes 1-3 is described. New templates have been successfully applied to the synthesis of macrocyclic polythialactones 4-9 by cyclization of corresponding stannathianes 1-3 with pimeloyl dichloride. 相似文献
33.
Optical sectioning in wide-field microscopy is achieved by illumination of the object with a continuously moving single-spatial-frequency pattern and detecting the image with a smart pixel detector array. This detector performs an on-chip electronic signal processing that extracts the optically sectioned image. The optically sectioned image is directly observed in real time without any additional postprocessing. 相似文献
34.
Lina Skardžiūtė Karolis Kazlauskas Jelena Dodonova Jonas Bucevičius Sigitas Tumkevičius Saulius Juršėnas 《Tetrahedron》2013
Pyrrolo[2,3-d]pyrimidine derivatives possessing different sterically-hindered end-groups at position 7 of the heterocycle were studied and compared with respect to nanoaggregate formation ability by the reprecipitation method in aqueous solutions. The emergence of nanoaggregates with an increasing water fraction in THF/water mixture was traced by observing sudden changes in spectral and transient fluorescence dynamics accompanied by fluorescence efficiency turn-on. The aggregation induced emission with a maximal 20-fold emission efficiency enhancement was obtained. Tuning of the nanoaggregates sizes from about 50 nm to 600 nm by increasing the THF/water ratio was revealed by electron microscopy. Almost perfect spherical shapes of the nanoaggregates and their structureless fluorescence bands similar to those of their neat amorphous films suggested an amorphous-like nature of the pyrrolo[2,3-d]pyrimidine-based nanoparticles. 相似文献
35.
Aanski Marijana M. Dobrijevi Jelena P. Redepovi Azra S. Vuji ura N. Jovanovi-anta Suzana S. 《Chromatographia》2009,70(11):1679-1683
The retention behaviour of a number of 16,17-secoestrone derivatives has been studied by LC and HPTLC on a polar cyanopropyl-bonded stationary phase using non-aqueous and aqueous-organic mobile phases. The retention behaviour has been discussed in terms of nature of the solute, eluent and stationary phase. The correlation between retention constants of 16,17-secoestrone derivatives obtained from reversed-phases and commercially available ACD log P software (Advanced Chemistry, Toronto, Canada) has also been examined.
相似文献36.
37.
This work presents the synthesis of novel unsymmetrical bolaamphiphiles bearing a sugar residue and a cationic glycine betaine moiety connected to both ends of a C22 or C32 oligomethylene bridging chain possessing or not a diacetylenic unit. Preliminary transmission electron microscopy (TEM) studies revealed the polymorphism of these bola lipids with regard to their self-assembled morphologies in water depending on the presence or not of the diacetylenic functionality and on alkyl chain length. 相似文献
38.
Dragana Vasiljevic Jelena Djuris Sergej Jakimenko Svetlana Ibric 《Journal of Dispersion Science and Technology》2017,38(12):1732-1737
In presented research, multiple W/O/W emulsions were developed by using experimental design method. A 24-1 fractional factorial design was performed by varying the following input parameters: primary polymeric emulsifier (PEG 30-dipolyhydroxystearate) concentration (0.8% and 2.4%), secondary polymeric emulsifier (Poloxamer 407) concentration (0.8% and 1.2%), electrolyte magnesium sulfate heptahydrate (0.08% and 0.4%) and electrolyte sodium chloride (0.08% and 0.4%). Multiple emulsions were prepared by a two-step emulsification process. Obtained emulsions were characterized with rheological measurements, conductivity and centrifugation tests. Factorial analysis revealed that the concentration of the primary emulsifier was the predominant factor influencing the phase separation, conductivity and maximal apparent viscosity. Additionally, electrolyte magnesium sulfate heptahydrate was more efficient in stabilizing these systems, compared to sodium chloride. The applied fractional factorial design method enabled determination of the optimal concentrations of the primary and secondary emulsifier, as well as the concentration of electrolytes, in order to obtain W/O/W emulsions with desired maximal apparent viscosities, low values of conductivity and without phase separation after centrifugation. 相似文献
39.
Mixed borohydride-chloride complexes of lanthanum and neodymium having the 2,5-bis{N-(2,6-diisopropylphenyl)iminomethyl}pyrrolyl ligand in the coordination sphere were synthesised by the reaction of potassium 2,5-bis{N-(2,6-diisopropylphenyl)iminomethyl}pyrrolyl [(DIP2-pyr)K] with a 1:1 mixture of [Ln(BH4)3(THF)3] and LnCl3 (Ln = La, Nd). Both compounds are dimeric in the solid state. The metal atoms are bridged almost symmetrically by two μ-chlorine atoms. Quantum chemical calculations for the lanthanum compound were performed to obtain a deeper insight into the bonding in the molecule. 相似文献