全文获取类型
收费全文 | 2094篇 |
免费 | 199篇 |
国内免费 | 113篇 |
专业分类
化学 | 1921篇 |
晶体学 | 46篇 |
力学 | 68篇 |
综合类 | 6篇 |
数学 | 19篇 |
物理学 | 346篇 |
出版年
2024年 | 1篇 |
2023年 | 12篇 |
2022年 | 21篇 |
2021年 | 29篇 |
2020年 | 61篇 |
2019年 | 59篇 |
2018年 | 66篇 |
2017年 | 50篇 |
2016年 | 100篇 |
2015年 | 78篇 |
2014年 | 91篇 |
2013年 | 153篇 |
2012年 | 82篇 |
2011年 | 111篇 |
2010年 | 97篇 |
2009年 | 94篇 |
2008年 | 80篇 |
2007年 | 92篇 |
2006年 | 81篇 |
2005年 | 88篇 |
2004年 | 99篇 |
2003年 | 74篇 |
2002年 | 55篇 |
2001年 | 43篇 |
2000年 | 65篇 |
1999年 | 46篇 |
1998年 | 38篇 |
1997年 | 44篇 |
1996年 | 39篇 |
1995年 | 49篇 |
1994年 | 29篇 |
1993年 | 30篇 |
1992年 | 31篇 |
1991年 | 24篇 |
1990年 | 30篇 |
1989年 | 24篇 |
1988年 | 23篇 |
1987年 | 34篇 |
1986年 | 28篇 |
1985年 | 26篇 |
1984年 | 21篇 |
1983年 | 14篇 |
1982年 | 26篇 |
1981年 | 19篇 |
1980年 | 19篇 |
1979年 | 20篇 |
1978年 | 6篇 |
1977年 | 3篇 |
1973年 | 1篇 |
排序方式: 共有2406条查询结果,搜索用时 0 毫秒
991.
Dr. Elham Baktash Dr. Jérôme Capitolis Dr. Lionel Tinat Dr. Clément Larquet Dr. Tsou Hsi Camille Chan Chang Dr. Jean-Jacques Gallet Dr. Fabrice Bournel Prof. Clément Sanchez Dr. Sophie Carenco Dr. David Portehault 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(47):11114-11120
Magnéli phases TinO2n−1 (3<n≤10) are mixed Ti4+/Ti3+ oxides with high electrical conductivity. When used for water remediation or electrochemical energy storage and conversion, they are nanostructured and exposed to various environments. Therefore, understanding their surface reactivity is of prime importance. Such studies have been hindered by carbon contamination from syntheses. Herein, this synthetic and characterization challenge is addressed through a new approach to 50 nm carbon-free Ti4O7 and Ti6O11 nanoparticles. It takes advantage of the different reactivities of rutile and anatase TiO2 nanoparticles towards H2, to use the former as precursor of TinO2n−1 and the latter as a diluting agent. This approach is combined with silica templating to restrain particle growth. The surface reactivity of the Magnéli nanoparticles under different atmospheres was then evaluated quantitatively by synchrotron-radiation-based X-ray photoelectron spectroscopy, which revealed oxidized surfaces with lower conductivity than the core. This finding sheds a new light on the charge transfer occurring in these materials. 相似文献
992.
Dr. Kamatham Narayanaswamy Bommaramoni Yadagiri Towhid Hossain Chowdhury Thokala Swetha Ashraful Islam Dr. Vinay Gupta Dr. Surya Prakash Singh 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(71):16320-16327
Herein, the synthesis of the novel acceptor–donor–acceptor (A–D–A)-structured small molecule Si-PO-2CN based on dithienosilole (DTS) as building block flanked by electron-rich phenoxazine (POZ) units, which are terminated with dicyanovinylene, is presented. Si-PO-2CN showed unique electrochemical and photophysical properties and has been successfully employed in perovskite solar cells (PSCs) as well as in bulk heterojunction organic solar cells (OSCs). The PSCs fabricated with dopant-free Si-PO-2CN as hole-transport material (HTM) exhibited a power conversion efficiency (PCE) of 14.1 % (active area=1.02 cm2). Additionally, a PCE of 5.6 % has been achieved for OSCs, which employed Si-PO-2CN as p-type donor material when blended with a [6,6]-phenyl C71 butyric acid methyl ester (PC71BM) acceptor. The versatile application of Si-PO-2CN provides a pathway for further implementation of DTS-based building blocks in solar cells for designing new molecules. 相似文献
993.
《Journal of separation science》2018,41(17):3404-3410
The thermal stability of poly[1‐(trimethylsilyl)‐1‐propyne] is investigated by heating the capillary column with this polymer as the stationary phase with the subsequent separation of the test mixture of light hydrocarbons. It is shown that heating of the column up to 130°C does not cause a decrease in efficiency or in the retention time of solutes. A further increase in temperature results in both decrease in column efficiency and sorbate retention. However, a decrease in column retentivity goes in one way for all the tested hydrocarbons. At the same time, the efficiency of the column is changed to a lesser degree for methane and ethane up to the temperature of polymer degradation, while for propane, butane, and iso‐butane the difference is rather sharp. The most expressed decrease in efficiency was found for iso‐butane: the column efficiency for this sorbate versus temperature of heating had two stages. The diffusion coefficients for sorbates in the polymeric phase were also evaluated and the sharp decrease in their values was found after the column heating. 相似文献
994.
Elena Bacalum 《液相色谱法及相关技术杂志》2017,40(2):59-68
Fluorocarbon stationary phases have taken great advances in recent years in liquid chromatography. Numerous studies to elucidate the retention mechanism have been undertaken that concluded the retention is driven by a multitude of factors, due to the presence of fluorine atoms in the molecule. Many applications in this domain have been described in the literature so far. Applications for other fields have also been published in various original papers for fluorocarbon silica. 相似文献
995.
Dr. Bo Shen Prof. Shouheng Sun 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(30):6757-6766
Permanent magnets are a class of critical materials for information storage, energy storage, and other magneto-electronic applications. Compared with conventional bulk magnets, magnetic nanoparticles (MNPs) show unique size-dependent magnetic properties, which make it possible to control and optimize their magnetic performance for specific applications. The synthesis of MNPs has been intensively explored in recent years. Among different methods developed thus far, chemical synthesis based on solution-phase reactions has attracted much attention owing to its potential to achieve the desired size, morphology, structure, and magnetic controls. This Minireview focuses on the recent chemical syntheses of strongly ferromagnetic MNPs (Hc>10 kOe) of rare-earth metals and FePt intermetallic alloys. It further discusses the potential of enhancing the magnetic performance of MNP composites by assembly of hard and soft MNPs into exchange-coupled nanocomposites. High-performance nanocomposites are key to fabricating super-strong permanent magnets for magnetic, electronic, and energy applications. 相似文献
996.
Summary It is not commonly appreciated that retention indices are temperature dependent. It is even less common to express this fact in more practical terms by saying that polarity is temperature dependent. Although the meaning of both statements is identical, we believe the second to be particularly relevant, since the majority of practical gas chromatographers tends to handle polarity as an invariable characteristic of a stationary phase.The variability of polarity with temperature is the major source of inadequate reproducibility of exact finger-printing, this particularly when gc/ms traces have to be compared to those obtained by pure gc. On the other hand, the temperature dependence provides a practical means to optimize the polarity of a given column for a given analysis. Film thickness is an essential parameter in this context because of its influence on column temperature and, therefore, on column polarity. 相似文献
997.
998.
999.
P. M. Ossi 《Il Nuovo Cimento D》1989,11(8):1123-1133
Summary The structural characteristics of quasi-crystalline phases obtained by ion irradiation are compared with those of the corresponding
amorphous structures. Chemical forces drive the formation of atomic clusters and their spatial organization under specific
geometric constraints. The same elementary structural units exist in quasi-crystalline and glassy phases which display identical
local order, their main difference being the degree of defect organization at the interface between locally ordered atomic
groups.
To speed up publication, the author of this paper has agreed to not receive the proofs for correction. 相似文献
1000.