全文获取类型
收费全文 | 1043篇 |
免费 | 43篇 |
国内免费 | 1篇 |
专业分类
化学 | 589篇 |
晶体学 | 14篇 |
力学 | 31篇 |
数学 | 76篇 |
物理学 | 377篇 |
出版年
2023年 | 11篇 |
2022年 | 16篇 |
2021年 | 16篇 |
2020年 | 12篇 |
2019年 | 26篇 |
2018年 | 21篇 |
2017年 | 15篇 |
2016年 | 46篇 |
2015年 | 14篇 |
2014年 | 39篇 |
2013年 | 66篇 |
2012年 | 72篇 |
2011年 | 74篇 |
2010年 | 57篇 |
2009年 | 48篇 |
2008年 | 57篇 |
2007年 | 58篇 |
2006年 | 61篇 |
2005年 | 49篇 |
2004年 | 43篇 |
2003年 | 36篇 |
2002年 | 38篇 |
2001年 | 19篇 |
2000年 | 11篇 |
1999年 | 3篇 |
1998年 | 6篇 |
1997年 | 6篇 |
1996年 | 12篇 |
1995年 | 6篇 |
1994年 | 10篇 |
1993年 | 12篇 |
1992年 | 13篇 |
1991年 | 6篇 |
1990年 | 9篇 |
1989年 | 13篇 |
1988年 | 6篇 |
1987年 | 6篇 |
1985年 | 5篇 |
1984年 | 9篇 |
1982年 | 3篇 |
1981年 | 11篇 |
1980年 | 6篇 |
1978年 | 3篇 |
1977年 | 4篇 |
1976年 | 6篇 |
1975年 | 5篇 |
1974年 | 4篇 |
1973年 | 4篇 |
1972年 | 5篇 |
1958年 | 1篇 |
排序方式: 共有1087条查询结果,搜索用时 15 毫秒
51.
52.
Research on Chemical Intermediates - The discharge of hexavalent chromium [Cr(VI)] has resulted in significant pollution because of the presence of Cr(VI) oxyanions. They are highly water-soluble,... 相似文献
53.
Dipak Ghosh Madhumita Lahiri Argha Deb Susobhan Das Krishnadas Purkait Biswanath Biswas Jayanta Roy Choudhury Rini Chatterjee Abdul Kayum Jafry 《The European Physical Journal C - Particles and Fields》2011,71(1):243-249
The scaled factorial moments and the multifractal moments have been investigated in different??-intervals to study the dynamical fluctuation of pions produced in 200 AGeV32S-Ag/Br interaction. In order to investigate the detail characteristics of intermittency behaviour, theF-moments are extracted up to the eighth order of moments in differentM-intervals. The analysis indicates a non-thermal phase transition and different regime of particle production during the hadronisation process. 相似文献
54.
55.
Shyamaprosad Goswami Subrata Jana Rinku Chakrabarty Hoong-Kun Fun 《Supramolecular chemistry》2013,25(3):143-148
A guanidine-based fluorescent receptor has been synthesised to study its binding behaviour towards anions (F? , Cl? , Br? , I? and AcO? ). The two donor N–H bonds of the receptor do not point in the same direction; rather, one N–H bond is intramolecularly hydrogen-bonded with the carbonyl oxygen atom. The nature of the donor–acceptor (DA) arrangement induces moderate binding properties. The binding behaviour towards monocarboxylic acids (benzoic acid and phenylacetic acid) is also compared. The binding behaviour of receptor 1 towards the F? anion is higher among the anions studied, whereas in the case of monocarboxylic acid, the binding constant with phenylacetic acid is higher than benzoic acid. 相似文献
56.
6-Alkylpyrano [3,2-c] quinolin-5(2H)-ones(11a-e) were obtained in excellent yields by simply refluxing propynyl and butymyl ethers (6) of 4-hydroxy-1-alkylquinolin-2H-ones (2) in chlorobenzene for 10h, 5-Prop-2-ynyloxy-2H-pyrano [3,2-c] quinoline (12) was also obtained from the thermal rearrangement of 2,4-bis prop-2-ynyloxyquinoline (4). 相似文献
57.
A simple and efficient method for the convenient synthesis of 2-arylbenzimidazole has been described on reaction with o-phenylenediamine and various aromatic aldehydes using cobalt(II) chloride hexahydrate as a catalyst. The method is cost-effective, high-yielding, clean, and selective. 相似文献
58.
An expedient three‐step procedure for the synthesis of trichlorophenol derivatives based on the acid‐catalyzed rearrangement of the bicyclic ketone precursors 6a–e in high overall yield is described. The bicyclic ketone precursors 6a–e were obtained from Diels–Alder cycloadducts of β‐substituted vinyl acetates with tetrachloro‐5,5‐dimethoxycyclopentadiene in two steps. 相似文献
59.
Zahra Afrasiabi Rosana Almudhafar Di Xiao Ekkehard Sinn Amitava Choudhury Aamir Ahmad Alok Vyas Fazlul Sarkar Subhash Padhye 《Transition Metal Chemistry》2013,38(6):665-673
A planar, polycyclic and aromatic hydrocarbon ligand, namely 9,10-phenanthrenequinone semicarbazone, and its transition metal complexes have been synthesized and structurally characterized. The in vitro antiproliferative activity of these compounds against five human cancer cell lines revealed that they were effective against androgen receptor-positive/negative prostate cancer cells as well as COX-positive pancreatic BxPC-3 cancer cell line. The driving force behind such antiproliferative activity seems to be the up-regulated COX expression in these cells, which was amenable for targeting through metal complexation. These structural motifs can, therefore, serve as a starting point for developing novel cytotoxic agents against the growing number of prostate and pancreatic cancers. 相似文献
60.
Ambar Kumar Choudhury Asim Kumar Ray Nirmolendu Roy 《Journal of carbohydrate chemistry》2013,32(8):1153-1163
Abstract Starting from L-fucose, D-glucose and lactose, methyl O-[2,3-di-O-benzoyl-4, 6-O-(4-methoxybenzylidene)-β-D-glucopyranosyl]-(1→4)-2,3-di-O-benzoyl-α-L-fucopyranoside and methyl O-(2,3,4,6-tetra-O-benzyl-β-D-galactopyranosyl)-(1→4)-O-(2,3,6-tri-O-benzyl-α-D-glucopyranosyl)-(1→4)-O-(methyl 2,3-di-O-benzoyl-β-D-glucopyranosyluronate)-(1→4)-2,3-di-O-benzoyl-α-L-fucopyranoside were synthesized. Removal of protecting groups gave the tetrasaccharide repeating unit of the antigen from Klebsiella type-16 in the form of its methyl ester methyl glycoside. 相似文献