全文获取类型
收费全文 | 359篇 |
免费 | 25篇 |
国内免费 | 9篇 |
专业分类
化学 | 259篇 |
晶体学 | 2篇 |
力学 | 14篇 |
数学 | 42篇 |
物理学 | 76篇 |
出版年
2023年 | 1篇 |
2022年 | 5篇 |
2021年 | 16篇 |
2020年 | 20篇 |
2019年 | 15篇 |
2018年 | 19篇 |
2017年 | 10篇 |
2016年 | 20篇 |
2015年 | 15篇 |
2014年 | 20篇 |
2013年 | 38篇 |
2012年 | 30篇 |
2011年 | 31篇 |
2010年 | 28篇 |
2009年 | 19篇 |
2008年 | 18篇 |
2007年 | 14篇 |
2006年 | 19篇 |
2005年 | 11篇 |
2004年 | 8篇 |
2003年 | 7篇 |
2002年 | 9篇 |
2001年 | 2篇 |
2000年 | 1篇 |
1999年 | 4篇 |
1997年 | 1篇 |
1995年 | 1篇 |
1994年 | 1篇 |
1988年 | 1篇 |
1986年 | 1篇 |
1984年 | 3篇 |
1983年 | 1篇 |
1982年 | 1篇 |
1980年 | 3篇 |
排序方式: 共有393条查询结果,搜索用时 31 毫秒
101.
Ramin Ghorbani-Vaghei 《Tetrahedron letters》2003,44(40):7529-7532
N,N′-Diiodo-N,N′-1,2-ethanediylbis(p-tolouenesulphonamide) [NIBTS] and catalytic trifluoroacetic acid can be used for the regioselective iodination of aromatic compounds in acetonitrile under mild conditions in excellent yields. 相似文献
102.
Joseph Shalika Ramin Takloo-Bighash Yuri Tschinkel 《Journal of the American Mathematical Society》2007,20(4):1135-1186
We prove Manin's conjecture concerning the distribution of rational points of bounded height, and its refinement by Peyre, for wonderful compactifications of semi-simple algebraic groups over number fields. The proof proceeds via the study of the associated height zeta function and its spectral expansion.
103.
This work describes the synthesis of Pd nanoparticles that are stabilized on CaAl-layered double hydroxide functionalized with Tris (tris(hydroxymethyl)aminomethane). The synthesized catalyst is characterized by several different analyses and has been successfully applied to the Suzuki–Miyaura reaction. 相似文献
104.
Mir Ali?FarajzadehEmail author Mortaza?Ebrahimi Ali?Ranji Elham?Feyz Vali?Bejani Ramin?Maleki 《Mikrochimica acta》2005,150(2):173-177
This study describes the sample preparation and two chromatographic techniques for determination of Tinuvin 622 in polyethylene. The first part of the two methods consisting of dissolving the polyethylene in boiling xylene is followed by addition of a methanolic solution of potassium hydroxide. The polymeric light stabilizer, Tinuvin 622, is thereby saponified to 4-hydroxy-2,2,6,6-tetramethyl-1-piperidineethanol (diol). Addition of the methanolic solution of the saponification reagent simultaneously precipitates the polyethylene matrix. Then the diol is quantified using either gas chromatography (GC) or high performance liquid chromatography (HPLC). For GC, a Macherey Nagel Optima-17 capillary column (30m×0.25mm ID, film thickness 0.25µm) is used. Nitrogen is used as carrier gas and make-up gas. The detection system is a flame ionization detector. For HPLC, an octadecyl silane (ODS) column (30cm×4mm, particle size 5µm) and a mobile phase methanol: water mixture (3:97, v/v) are used. Detection of analyte is carried out at 215nm. Both methods can be used to determine Tinuvin 622 in polyethylene in the concentration range of 0.02–1%, which represents the usual application concentration. 相似文献
105.
Hemmateenejad B Akhond M Miri R Shamsipur M 《Journal of chemical information and computer sciences》2003,43(4):1328-1334
106.
Javad Azizian Ramin Miri Mohammad Kazem Mohammadi Fatemeh Sheikholeslami Farahani Javad Hosseini Mohsen Nikpour 《Phosphorus, sulfur, and silicon and the related elements》2013,188(8):1782-1787
New (pyrimido[4,5-e][1,3,4]thiadiazin-7-yl)hydrazines were synthesized via the cyclocondensation of alkyl-2-phenylhydrazinecarbodithioates as bidentate nucleophiles with 5-bromo-2,4-dichloro-6-methylpyrimidine as an electrophile and further replacement of chlorine atom on the seven number position of pyrimido[4,5-e][1,3,4]thiadiazin by hydrazine in boiling ethanol. 相似文献
107.
We, herein, describe a novel, simple, efficient and one‐pot multi‐component procedure for the synthesis of substituted pyrimido[4,5‐d]pyrimidines via reaction of N,N‐dimethyl‐6‐amino uracil, isothiocyanate and aromatic aldehydes promoted by 7‐aminonaphthalene‐1,3‐disulfonic acid (ANDSA)‐functionalized magnetic Fe3O4@SiO2 in water as solvent and without using any other harmful organic reagents. Compared with other reactions, using these organic–inorganic hybrid heterogeneous catalysts can help us to achieve a green procedure, high catalytic activity, easy recovery with an external magnetic field, and short reaction times. 相似文献
108.
Research on Chemical Intermediates - HZSM-5 (HZ(1) and HZ(2)) zeolites synthesized with various framework aluminum distributions and also cobalt-modified H-form zeolites (Co/HZ(1) and Co/HZ(2))... 相似文献
109.
Badrnezhad Ramin Pourfarzad Hamed Madram Ali Reza Ganjali Mohammad Reza 《Russian Journal of Electrochemistry》2019,55(4):272-280
Russian Journal of Electrochemistry - The present paper aims to compare the corrosion protection performance of electrodeposited Ni?P with Ni–P–C nanocomposite coatings in 3.5 wt... 相似文献
110.
Faroughi Niya Homayoun Hazeri Nourallah Rezaie Kahkhaie Mahboobeh Maghsoodlou Malek Taher 《Research on Chemical Intermediates》2020,46(3):1685-1704
Research on Chemical Intermediates - In this study, an efficient and novel procedure has been reported for loading sulfanilic acid on the surface of magnetite Fe3O4 nanoparticles using... 相似文献