全文获取类型
收费全文 | 15391篇 |
免费 | 2715篇 |
国内免费 | 837篇 |
专业分类
化学 | 18149篇 |
晶体学 | 59篇 |
力学 | 28篇 |
综合类 | 14篇 |
数学 | 19篇 |
物理学 | 674篇 |
出版年
2023年 | 245篇 |
2022年 | 469篇 |
2021年 | 645篇 |
2020年 | 1237篇 |
2019年 | 942篇 |
2018年 | 762篇 |
2017年 | 622篇 |
2016年 | 1219篇 |
2015年 | 1066篇 |
2014年 | 1065篇 |
2013年 | 1240篇 |
2012年 | 950篇 |
2011年 | 1022篇 |
2010年 | 880篇 |
2009年 | 908篇 |
2008年 | 866篇 |
2007年 | 786篇 |
2006年 | 733篇 |
2005年 | 662篇 |
2004年 | 676篇 |
2003年 | 541篇 |
2002年 | 208篇 |
2001年 | 105篇 |
2000年 | 114篇 |
1999年 | 81篇 |
1998年 | 85篇 |
1997年 | 150篇 |
1996年 | 95篇 |
1995年 | 110篇 |
1994年 | 56篇 |
1993年 | 36篇 |
1992年 | 32篇 |
1991年 | 33篇 |
1990年 | 30篇 |
1989年 | 19篇 |
1988年 | 27篇 |
1987年 | 21篇 |
1986年 | 67篇 |
1985年 | 14篇 |
1984年 | 9篇 |
1983年 | 7篇 |
1980年 | 9篇 |
1979年 | 9篇 |
1978年 | 9篇 |
1975年 | 6篇 |
1974年 | 6篇 |
1973年 | 6篇 |
1972年 | 11篇 |
1970年 | 7篇 |
1966年 | 9篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
11.
This review provides a comprehensive evaluation of solidified floating organic drop microextraction (SFODME) procedures for metal ions preconcentration and their contributions to green chemistry. In this article we focused on the modifications that have been performed in the recent years to improve this environmentally friendly procedure. Among the most important of these modifications are the inclusion of ultrasonic energy, vortex and air agitation to enhance the dispersion process. The article also discussed new challenges in the procedure by using more ecofriendly solvents as extractants such as ionic liquids, deep eutectic. and supramolecular solvents. The coupling of SFODME with solid phase extraction increases selectivity and efficiency of the preconcentration procedure. 相似文献
12.
13.
14.
Yan-Cen Liu Dr. Shu Peng Lora Angelova Prof. Dr. Werner M. Nau Dr. Andreas Hennig 《ChemistryOpen》2019,8(11):1350-1354
The combination of the macrocyclic hosts p-sulfonatocalix[4]arene and cucurbit[7]uril with the fluorescent dyes lucigenin and berberine affords two label-free enzyme assays for the detection of kinase and phosphatase activity by fluorescence monitoring. In contrast to established assays, no substrate labeling is required. Since phosphorylation is one of the most important regulatory mechanisms in biological signal transduction, the assays should be useful for identification of inhibitors and activators in high-throughput screening (HTS) format for drug discovery. 相似文献
15.
以1978年改革开放以来人民教育出版社出版的5套高中化学教科书作为研究对象,梳理其物质结构内容的演变,发现近40年来高中化学教科书中物质结构内容选择呈钟摆现象,同时其内容组织的结构化理念日益清晰。此外,为新时期我国高中化学教科书的编写提供了一些建议。 相似文献
16.
17.
18.
19.
Simen Gjelseth Antonsen Arne Joakim C. Bunkan Tomas Mikoviny Yngve Stenstrøm Armin Wisthaler 《Molecular physics》2020,118(15)
The kinetics of the O3, OH and NO3 radical reactions with diazomethane were studied in smog chamber experiments employing long-path FTIR and PTR-ToF-MS detection. The rate coefficients were determined to be k CH2NN+O3?=?(3.2?±?0.4)?×?10?17 and k CH2NN+OH?=?(1.68?±?0.12)?×?10?10 cm3 molecule?1 s?1 at 295?±?3?K and 1013?±?30 hPa, whereas the CH2NN?+?NO3 reaction was too fast to be determined in the static smog chamber experiments. Formaldehyde was the sole product observed in all the reactions. The experimental results are supported by CCSD(T*)-F12a/aug-cc-pVTZ//M062X/aug-cc-pVTZ calculations showing the reactions to proceed exclusively via addition to the carbon atom. The atmospheric fate of diazomethane is discussed. 相似文献
20.
Zhaohui Zhang Hui Liu Qingzhu Sun Feng Shao Qingyan Pan Prof. Tao Zhuang Prof. Yingjie Zhao 《ChemistryOpen》2020,9(3):381-385
A fluorescent monolayered two-dimensional polymer (2DP) containing both tetraphenylethylene (TPE) and imine linkages is synthesized at air-water interface using the Langmuir-Blodgett method. We designed TPE-based monomers with long distances between the TPE and the imine linkages to avoid the charge transfer and therefore keep the fluorescence. A monolayered 2DP provided with more than 104 μm2 in domain size and around 0.8 nm thickness was obtained through a successive Schiff base reaction at air-water interface. The nanostructures and fluorescent property of 2DP films were characterized by optical microscopy, SEM, TEM, AFM and fluorescence spectrum. Most importantly, the tip-enhanced Raman spectroscopy (TERS) was utilized here to confirm the success of the polycondensation of monolayered 2DP. 相似文献