全文获取类型
收费全文 | 1789篇 |
免费 | 313篇 |
国内免费 | 126篇 |
专业分类
化学 | 2032篇 |
晶体学 | 12篇 |
综合类 | 5篇 |
物理学 | 179篇 |
出版年
2024年 | 3篇 |
2023年 | 26篇 |
2022年 | 51篇 |
2021年 | 78篇 |
2020年 | 103篇 |
2019年 | 91篇 |
2018年 | 50篇 |
2017年 | 61篇 |
2016年 | 121篇 |
2015年 | 113篇 |
2014年 | 135篇 |
2013年 | 158篇 |
2012年 | 125篇 |
2011年 | 104篇 |
2010年 | 105篇 |
2009年 | 116篇 |
2008年 | 105篇 |
2007年 | 106篇 |
2006年 | 88篇 |
2005年 | 65篇 |
2004年 | 66篇 |
2003年 | 50篇 |
2002年 | 62篇 |
2001年 | 26篇 |
2000年 | 16篇 |
1999年 | 14篇 |
1998年 | 15篇 |
1997年 | 24篇 |
1996年 | 17篇 |
1995年 | 35篇 |
1994年 | 18篇 |
1993年 | 18篇 |
1992年 | 12篇 |
1991年 | 6篇 |
1990年 | 6篇 |
1989年 | 6篇 |
1988年 | 9篇 |
1987年 | 3篇 |
1986年 | 6篇 |
1985年 | 2篇 |
1984年 | 3篇 |
1982年 | 2篇 |
1980年 | 1篇 |
1979年 | 1篇 |
1976年 | 1篇 |
1975年 | 1篇 |
1974年 | 1篇 |
1970年 | 1篇 |
1968年 | 1篇 |
1966年 | 1篇 |
排序方式: 共有2228条查询结果,搜索用时 31 毫秒
991.
Six fungal isolates belong to Aspergillus niger, Penicillium spp., and Pleurotus osstreatus were used for decolourization activities of some acid and reactive dyes, after they screened for optimum efficiency and the condition for temperature and pH were optimized The results obtained indicated that Pleurotus osstreatus and Aspergillus niger 1 and 2 are more efficient than Penicillium spp., with the two kinds of dyes used. The results also revealed that, the maximum degradation activities of these isolates for acid dyes was at pH 5 after 9 days incubation period and at pH 5-6, for reactive dyes. Simulated and actual waste water samples were used in the experiments. Fungi decolourization of synthetic dyes according to their life state group 1: (living cells) to biodegradation and biosorb dyes. The major mechanism is biodegradation because they can produce the lignin modifying enzymes, lactose, manganese peroxides (Lip) to mineralize synthetic lignin of dyes. Group 2: dead cells (Fungal biomass) to adsorb dyes. 相似文献
992.
993.
Syed Muhammad Usama Tye Thompson Kevin Burgess 《Angewandte Chemie (International ed. in English)》2019,58(27):8974-8976
Polymethine bridges in cyanine dyes may be constrained by setting them into edge‐fused ring systems, or extended by conjugation with carefully chosen heterocycles. Recent studies have shown that modifications like these can give significantly brighter dyes with red‐shifted absorbance and emission maxima. 相似文献
994.
Gyuzel Yu. Mitronova Dr. Vladimir N. Belov Dr. Mariano L. Bossi Dr. Christian A. Wurm Dr. Lars Meyer Dr. Rebecca Medda Dr. Gael Moneron Dr. Stefan Bretschneider Dr. Christian Eggeling Dr. Stefan Jakobs Dr. Stefan W. Hell Prof. Dr. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2010,16(15):4477-4488
New photostable rhodamine dyes represented by the compounds 1 a – r and 3 – 5 are proposed as efficient fluorescent markers with unique combination of structural features. Unlike rhodamines with monoalkylated nitrogen atoms, N′,N‐bis(2,2,2‐trifluoroethyl) derivatives 1 e , 1 i , 1 j , 3 ‐H and 5 were found to undergo sulfonation of the xanthene fragment at the positions 4′ and 5′. Two fluorine atoms were introduced into the positions 2′ and 7′ of the 3′,6′‐diaminoxanthene fragment in compounds 1 a – d , 1 i – l and 1 m – r . The new rhodamine dyes may be excited with λ=488 or 514 nm light; most of them emit light at λ=512–554 nm (compounds 1 q and 1r at λ=576 and 589 nm in methanol, respectively) and have high fluorescence quantum yields in solution (up to 98 %), relatively long excited‐state lifetimes (>3 ns) and are resistant against photobleaching, especially at high laser intensities, as is usually applied in confocal microscopy. Sulfonation of the xanthene fragment with 30 % SO3 in H2SO4 is compatible with the secondary amide bond (rhodamine‐CON(Me)CH2CH2COOH) formed with MeNHCH2CH2COOCH3 to providing the sterically unhindered carboxylic group required for further (bio)conjugation reactions. After creating the amino reactive sites, the modified derivatives may be used as fluorescent markers and labels for (bio)molecules in optical microscopy and nanoscopy with very‐high light intensities. Further, the new rhodamine dyes are able to pass the plasma membrane of living cells, introducing them as potential labels for recent live‐cell‐tag approaches. We exemplify the excellent performance of the fluorinated rhodamines in optical microscopy by fluorescence correlation spectroscopy (FCS) and stimulated emission depletion (STED) nanoscopy experiments. 相似文献
995.
Caroline Cannizzo Sonia Amigoni‐Gerbier Michel Frigoli Chantal Larpent 《Journal of polymer science. Part A, Polymer chemistry》2008,46(10):3375-3386
A series of stable and translucent colored nanolatex, that is, colloidal aqueous suspensions of dye‐tagged polymer nanoparticles (NPs) in the 15‐ to 20‐nm diameter range, have been prepared by covalent attachment of azobenzene chromophores to the surface of reactive NPs. Primary crosslinked NPs bearing chlorobenzyl groups were produced by microemulsion copolymerization of styrene and vinylbenzylchloride. Amine‐functionalized NPs were obtained after a second functionalization step with polyamines (cyclam and polypropyleneimine dendrimers of first and third generations). Dye‐doped particles were obtained by reacting pyridylazo‐dimethylaminobenzene (PADA) with chlorobenzyl‐NPs and by reacting amine‐reactive dimethylaminoazobenzene dyes (DABsyl, DAB‐ITC) as well as Disperse Red 1 acrylate with polyamine‐coated NPs. Regardless the dye solubility, the grafting readily proceeded in aqueous suspensions at room temperature in the presence of a cationic surfactant without added solvent. Purple, red, and orange suspensions (maximum absorption around 550, 500, 430 nm), with dye loads ranging from 0.3 to 1.2 mmol/g, corresponding to 400–1800 azobenzene residues per NP, are obtained. The reported results indicate that functional polymer NPs, with remarkably accessible multiple anchoring sites, are useful building blocks. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 3375–3386, 2008 相似文献
996.
997.
Toshiaki Enoki Mizuka Sano Hiroo Inokuchi 《Molecular Crystals and Liquid Crystals》2013,570(1):401-411
The hydrogen adsorption in alkali metal complexes of graphite and triphenylene has been investigated by means of ESR and electrical resistivity under hydrogen atmosphere. In the first stage graphite compound C8Rb, hydrogen molecules are dissociated into atoms which are stabilized in graphite gaps. C8K has a two stage hydrogen adsorption process: dissociation and charge transfer. For C8Cs, the catalytic activity for hydrogen comes from the surface. The second stage compounds C24M (M=K, Rb, and Cs) show weaker activities for hydrogen than the first stage ones. Triphenylene-potassium complex has a two stage process for hydrogen adsorption. 相似文献
998.
Stephanie Delbaere Elena V. Tulyakova Emilie Marmois Gediminas Jonusauskas Elena N. Gulakova Yuri V. Fedorov Olga A. Fedorova 《Tetrahedron》2013
We report here about effective FRET process (73–99%) in mono-Mg2+ complexes of symmetrical crown ether bis(styryl) dyes. The FRET process has not been observed in the free state and in binuclear complexes. The formation of mononuclear complex provides two styrylic fragments with appropriate positions of absorption and emission bands for FRET. The other important parameter for FRET is the proper geometric orientation of both chromophores, which attain sandwich conformation with close positioning of complexed and free styryl fragments induced by ion-modulated geometry reorganization of the bis-dye. 相似文献
999.
1000.
Hyunbong Choi Dr. Ines Raabe Dr. Duckhyun Kim Dr. Francesca Teocoli Chulwoo Kim Kihyung Song Prof. Dr. Jun‐Ho Yum Dr. Jaejung Ko Prof. Dr. Md. K. Nazeeruddin Dr. Michael Grätzel Prof. Dr. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2010,16(4):1193-1201
We have designed and synthesized highly efficient organic sensitizers with a planar thienothiophene–vinylene–thienothiophene linker. Under standard global AM 1.5 solar conditions, the JK‐113 ‐sensitized cell gave a short circuit photocurrent density (Jsc) of 17.61 mA cm?2, an open‐circuit voltage (Voc) of 0.71 V, and a fill factor (FF) of 72 %, corresponding to an overall conversion efficiency (η) of 9.1 %. The incident monochromatic photo‐to‐current conversion efficiency (IPCE) of JK‐113 exceeds 80 % over the spectral region from 400 to 640 nm, reaching its maximum of 93 % at 475 nm. The band tails off toward 770 nm, contributing to the broad spectral light harvesting. Solar‐cell devices based on the sensitizer JK‐113 in conjunction with a volatile electrolyte and a solvent‐free ionic liquid electrolyte gave high conversion efficiencies of 9.1 % and 7.9 %, respectively. The JK‐113 ‐based solar cell fabricated using a solvent‐free ionic liquid electrolyte showed excellent stability under light soaking at 60 °C for 1000 h. 相似文献