全文获取类型
收费全文 | 11427篇 |
免费 | 1331篇 |
国内免费 | 424篇 |
专业分类
化学 | 4936篇 |
晶体学 | 25篇 |
力学 | 1079篇 |
综合类 | 38篇 |
数学 | 5153篇 |
物理学 | 1951篇 |
出版年
2023年 | 146篇 |
2022年 | 90篇 |
2021年 | 203篇 |
2020年 | 410篇 |
2019年 | 301篇 |
2018年 | 272篇 |
2017年 | 243篇 |
2016年 | 461篇 |
2015年 | 467篇 |
2014年 | 585篇 |
2013年 | 988篇 |
2012年 | 654篇 |
2011年 | 668篇 |
2010年 | 466篇 |
2009年 | 745篇 |
2008年 | 698篇 |
2007年 | 741篇 |
2006年 | 629篇 |
2005年 | 485篇 |
2004年 | 455篇 |
2003年 | 438篇 |
2002年 | 350篇 |
2001年 | 338篇 |
2000年 | 285篇 |
1999年 | 217篇 |
1998年 | 232篇 |
1997年 | 196篇 |
1996年 | 198篇 |
1995年 | 160篇 |
1994年 | 118篇 |
1993年 | 120篇 |
1992年 | 85篇 |
1991年 | 78篇 |
1990年 | 65篇 |
1989年 | 52篇 |
1988年 | 53篇 |
1987年 | 40篇 |
1986年 | 54篇 |
1985年 | 36篇 |
1984年 | 49篇 |
1983年 | 16篇 |
1982年 | 28篇 |
1981年 | 30篇 |
1980年 | 22篇 |
1979年 | 26篇 |
1978年 | 44篇 |
1977年 | 41篇 |
1976年 | 40篇 |
1975年 | 15篇 |
1974年 | 15篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
82.
83.
《印度化学会志》2023,100(4):100960
Disperse Red 177(9a), Disperse Red 343(9b), Disperse Blue 165(9c), Disperse Blue 165.1(9d), Disperse Blue 366(9e), and Disperse Blue 148(9f) were examined in the solvent. During silicon nanomicelle dyeing, we employed 9(a–f) azo disperse dyes on polyester. On polyester fabric, dye 9(a–f) offers equal washing, light, and rubbing fastness in both the conventional and silicone nanomicelle techniques. The dye can now be transported directly into the fibre core without the use of auxiliary dyes owing to the reduction in the particle size of azo dyes, which is made possible by nanoemulsions superior dispersion. The levelling property of the dispersed dye is enhanced by the dyeing process. When both techniques are applied, the lightfastness properties of all dyes are improved. It provides a very good to outstanding protection factor for textile materials. These 9(a–f) azo disperse dyes have moderate to outstanding photostability, net electrophilicity index, and lightfastness. 相似文献
84.
85.
Florentin Coppey Cédric Schelling Jean-Luc Veuthey Pierre Esseiva 《Helvetica chimica acta》2023,106(8):e202300052
In the past few years, there has been significant interest within the forensic community regarding the deployment of portable solutions that provide real-time results. This article introduces an innovative technology or technology architecture that enables the integration of a handheld device, specifically, Viavi MicroNIR, with a cloud-based system. This cloud system encompasses a server responsible for data processing and a mobile application acting as a user interface. To demonstrate the transformative impact of this technology on field operators, the analysis of cannabis specimens has been utilized. System's capacity to distinguish between CBD-type and THC-type cannabis has been particularly highlighted, along with the remarkable congruence observed between the near-infrared (NIR) spectra and the reference analytical method involving ultra-high-performance liquid chromatography (UHPLC) The article will present the advantages of this application primarily focusing on its potential to alleviate the burden on laboratories by expediting routine illicit drug analysis. Viavi MicroNIR technology provides laboratory personnel with additional time to handle more complex cases, thereby enhancing overall efficiency. 相似文献
86.
Shivani Arora Tavinder Singh Umasankar Mondal Dr. Anand Singh 《European journal of organic chemistry》2023,26(30):e202300469
A visible light mediated protocol for the synthesis of polyhalogenated and deuterated δ- and γ-lactams from readily available alkyl halides is reported. The reaction involves the generation of haloalkyl radicals through halogen atom transfer (XAT) and subsequent arylalkylation of olefins to afford dihydroisoquinolinones and oxindoles. This new XAT protocol exhibits wide scope under mild conditions and enables access to new halogenated chemical space. 相似文献
87.
Meiyun Su Lina Guo Peiyu Mao Meng Xiao Prof. Dr. Wenjie Liu Prof. Dr. Shaohua Wang 《European journal of organic chemistry》2023,26(29):e202300268
The catalyst-free electrochemical halogenation and trifluoromethylation of 4H-pyrido[1,2-a]pyrimidin-4-ones was realized under external-oxidant-free conditions. This strategy provides an easy and green access to functionalized new 4H-pyrido[1,2-a]pyrimidin-4-one derivatives with broad scope, good functional group tolerance and high regioselectivity. 相似文献
88.
Xuejian Li Bangzhong Wang Dr. Dong Li Dr. Jinfeng Zhao Prof. Dr. Jingping Qu Prof. Dr. Yuhan Zhou 《European journal of organic chemistry》2023,26(15):e202201452
An efficient and environmentally friendly methodology for 3,3-dichlorination and 2-oxidation of indole derivatives is described. Using KI as promotor, MCl (M=K, Na) as chlorine source, and oxone as oxidant, the reaction proceeds smoothly affording various functionalized 3,3-dichloro-2-oxindoles in moderate to excellent yields. This strategy can also be extended to 3-substituted indoles. With a broad substrate scope, it is a practical approach to 3,3-disubstituted-2-oxindoles. 相似文献
89.
Wei-Chen Zhu Yi-Fan Jiang Xin-Yu Liu Shi-Yin Tian Prof. Weidong Rao Prof. Shu-Su Shen Assoc. Prof. Ping Song Dr. Daopeng Sheng Prof. Shun-Yi Wang 《European journal of organic chemistry》2023,26(25):e202300379
A photoinduced synthesis of β-keto thiosulfone/β-keto selenosulfone by the reaction of α-bromoacetophenone with thiosulfonate/selenosulfonate under metal-free and visible light irradiation conditions is developed. Two C−S bonds or one C−S bond and one C−Se bond were constructed simultaneously. 相似文献
90.
Smaller cyclic peptides containing non-proteinogenic amino acids have garnered much attention for use as drugs, but their chemical synthesis is extremely challenging. In this study, a rapid (60.5 min) synthesis of 7- and 14-membered cyclic peptides containing N-methyl- and β-amino acids was achieved by only switching the concentrations (0.20 M or 0.01 M) of the substrates. The developed approach required neither expensive transition-metals nor expensive coupling agents. As far as we could ascertain, this is the first report of the synthesis of smaller (≤16-membered) cyclic N-methylated peptides via dimerization-cyclization strategy. 相似文献