全文获取类型
收费全文 | 2097篇 |
免费 | 125篇 |
国内免费 | 7篇 |
专业分类
化学 | 1781篇 |
晶体学 | 13篇 |
力学 | 28篇 |
数学 | 228篇 |
物理学 | 179篇 |
出版年
2023年 | 31篇 |
2022年 | 25篇 |
2021年 | 84篇 |
2020年 | 93篇 |
2019年 | 67篇 |
2018年 | 35篇 |
2017年 | 42篇 |
2016年 | 84篇 |
2015年 | 92篇 |
2014年 | 86篇 |
2013年 | 123篇 |
2012年 | 161篇 |
2011年 | 199篇 |
2010年 | 111篇 |
2009年 | 90篇 |
2008年 | 141篇 |
2007年 | 118篇 |
2006年 | 105篇 |
2005年 | 86篇 |
2004年 | 80篇 |
2003年 | 56篇 |
2002年 | 40篇 |
2001年 | 17篇 |
2000年 | 11篇 |
1999年 | 12篇 |
1998年 | 10篇 |
1997年 | 7篇 |
1996年 | 15篇 |
1995年 | 6篇 |
1994年 | 11篇 |
1993年 | 14篇 |
1992年 | 6篇 |
1991年 | 10篇 |
1990年 | 7篇 |
1988年 | 8篇 |
1987年 | 5篇 |
1985年 | 14篇 |
1984年 | 11篇 |
1982年 | 18篇 |
1981年 | 8篇 |
1980年 | 7篇 |
1979年 | 11篇 |
1978年 | 7篇 |
1977年 | 6篇 |
1976年 | 14篇 |
1975年 | 5篇 |
1974年 | 5篇 |
1973年 | 9篇 |
1972年 | 3篇 |
1930年 | 3篇 |
排序方式: 共有2229条查询结果,搜索用时 15 毫秒
101.
102.
Soranyel González-Carrero Miguel de la Guardia Raquel E Galian Julia Pérez-Prieto 《ChemistryOpen》2014,3(5):199-205
A flexible, highly sensitive sensor of oxygen in non-aqueous solvents is described. It consists of CdSe/ZnS nanoparticles decorated with a considerable number of pyrene units, thus making the formation of the pyrene excimer possible. The emission of the pyrene excimer and that of the nanoparticle are suitably separated from each other and also from the excitation wavelength. This sensor can be applied as a ratiometric oxygen sensor by using the linear response of the pyrene excimer lifetime combined with the linear response of the nanoparticle excited state lifetime. This nanohybrid has been assayed in seven media with different dielectric constants and viscosities over the whole oxygen concentration range. In addition, the sensor versatility provides an easy way for monitoring oxygen diffusion through systems. 相似文献
103.
104.
Eremina Julia A. Smirnova Ksenia S. Lider Elizaveta V. Klyushova Lyubov’ S. Sheven’ Dmitriy G. Potkin Vladimir I. 《Transition Metal Chemistry》2022,47(1):19-30
Transition Metal Chemistry - In this study, Ni(II) and Co(II) complexes [Co(H2O)2L2] (1), [Ni(H2O)2L2] (2), [Co(phen)L2] (3), [Ni(phen)L2]·2H2O·EtOH (4·2H2O), and... 相似文献
105.
Dr. Gordon Jacob Boehlich Hannes Sterzel Prof. Dr. Julia Rehbein Ass. Prof. Dr. Nina Schützenmeister 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(71):e202202619
Due to their high stability towards enzymatic hydrolysis C-acyl glycosidic compounds are useful synthetic intermediates for potential candidates in drug discovery. Syntheses for C-acyl mannosides have remained scarce and usually employ donors obtained from lengthy syntheses. Furthermore, syntheses of unprotected C-acyl mannosides have not been reported so far, due to the incapability of the C-acyl mannoside motif with deprotection conditions for protective groups commonly used in carbohydrate chemistry. Herein, we report an efficient and highly α-selective four-step one-pot method for the synthesis of C-acyl α-d -manno-, l -rhamno- and d -lyxopyranosides from easily accessible persilylated monosaccharides and dithianes requiring only trace amounts of a copper source as catalyst and explain the crucial role of the catalyst by mechanistic studies. Furthermore, the C-acyl α-glycosides were easily isomerized to give rapid access to their β-anomers. 相似文献
106.
107.
108.
Adriana Aniceto Julia Montenegro Rafael da Silva Cadena Anderson Junger Teodoro 《Molecules (Basel, Switzerland)》2021,26(2)
Amazonian fruits are excellent sources of bioactive compounds and can be used in beverages to improve the nutritional and sensorial characteristics. The present study aimed to develop a blend of murici (Byrsonima Crassifolia (L.) Kunth) and taperebá (Spondias Mombin L.) through experimental design and investigating the nutritional and sensorial characteristics of fruits and beverages. The murici was highlighted as higher vitamin C content (58.88 mg · 100 g−1) compared to taperebá (25.93 mg · 100 g−1). The murici and taperebá are good sources of total phenolic compounds (taperebá 1304.15 ± 19.14 mgGAE · 100 g−1 and the murici of 307.52 ± 19.73 mg GAE · 100 g−1) and flavonoids (174.87 ± 1.76 μgQE/g and 129.46 ± 10.68 μgQE/g, murici and taperebá, respectively), when compared to other Brazilian fruits. The antioxidant capacity in different methods revealed that the taperebá had a higher average in the results, only in the ORAC method and did not present a significant difference (p > 0.05) in relation to the murici. The beverage development was performed using experimental design 23, showed through sensory analysis and surface response methodology that murici and high sugar content (between 12.5 and 14.2% of sugar) influenced in sensory acceptance. Our findings indicate that beverages with improved nutrition and a sensory acceptance can be prepared using taperebá and murici fruits. 相似文献
109.
Daniel Wechsler Cynthia Carolina Fernndez Julia Kbl Lisa-Marie Augustin Corinna Stumm Norbert Jux Hans-Peter Steinrück Federico Jos Williams Ole Lytken 《Molecules (Basel, Switzerland)》2021,26(10)
Porphyrins are large organic molecules that are interesting for different applications, such as photovoltaic cells, gas sensors, or in catalysis. For many of these applications, the interactions between adsorbed molecules and surfaces play a crucial role. Studies of porphyrins on surfaces typically fall into one of two groups: (1) evaporation onto well-defined single-crystal surfaces under well-controlled ultrahigh vacuum conditions or (2) more application-oriented wet chemical deposition onto less well-defined high surface area surfaces under ambient conditions. In this study, we will investigate the wet chemical deposition of 5-(monocarboxyphenyl)-10,15,20-triphenylporphyrin (MCTPP) on well-defined rutile TiO2(110) single crystals under ambient conditions. Prior to deposition, the TiO2(110) crystals were also cleaned wet-chemically under ambient conditions, meaning none of the preparation steps were done in ultrahigh vacuum. However, after each preparation step, the surfaces were characterized in ultrahigh vacuum with X-ray photoelectron spectroscopy (XPS) and the result was compared with porphyrin layers prepared in ultrahigh vacuum (UHV) by evaporation. The differences of both preparations when exposed to zinc ion solutions will also be discussed. 相似文献
110.
If the baryon asymmetry of the Universe is produced by leptogenesis, CP violation is required in the lepton sector. In the seesaw extension of the standard model with three hierarchical right-handed neutrinos, we show that the baryon asymmetry is insensitive to the Pontecorvo-Maki-Nagakawa-Sakata phases: thermal leptogenesis can work for any value of the observable phases. This result was well known when there were no flavor effects in leptogenesis; we show that it remains true when flavor effects are included. 相似文献