全文获取类型
收费全文 | 233073篇 |
免费 | 7531篇 |
国内免费 | 3821篇 |
专业分类
化学 | 123466篇 |
晶体学 | 3655篇 |
力学 | 11041篇 |
综合类 | 141篇 |
数学 | 25430篇 |
物理学 | 80692篇 |
出版年
2022年 | 2016篇 |
2021年 | 2843篇 |
2020年 | 3161篇 |
2019年 | 3326篇 |
2018年 | 3815篇 |
2017年 | 3591篇 |
2016年 | 5307篇 |
2015年 | 3730篇 |
2014年 | 5457篇 |
2013年 | 11364篇 |
2012年 | 9997篇 |
2011年 | 11522篇 |
2010年 | 7863篇 |
2009年 | 7649篇 |
2008年 | 9846篇 |
2007年 | 9757篇 |
2006年 | 9298篇 |
2005年 | 8122篇 |
2004年 | 7364篇 |
2003年 | 6391篇 |
2002年 | 6224篇 |
2001年 | 6981篇 |
2000年 | 5381篇 |
1999年 | 4365篇 |
1998年 | 3533篇 |
1997年 | 3535篇 |
1996年 | 3272篇 |
1995年 | 3035篇 |
1994年 | 2801篇 |
1993年 | 2612篇 |
1992年 | 2964篇 |
1991年 | 2890篇 |
1990年 | 2797篇 |
1989年 | 2539篇 |
1988年 | 2540篇 |
1987年 | 2527篇 |
1986年 | 2382篇 |
1985年 | 3033篇 |
1984年 | 3247篇 |
1983年 | 2674篇 |
1982年 | 2827篇 |
1981年 | 2793篇 |
1980年 | 2644篇 |
1979年 | 2729篇 |
1978年 | 2821篇 |
1977年 | 2819篇 |
1976年 | 2887篇 |
1975年 | 2671篇 |
1974年 | 2644篇 |
1973年 | 2776篇 |
排序方式: 共有10000条查询结果,搜索用时 78 毫秒
51.
Synthesis of Small‐Sized,Porous, and Low‐Toxic Magnetite Nanoparticles by Thin POSS Silica Coating 下载免费PDF全文
Dr. Swee Kuan Yen D. Prathyusha Varma Wei Mei Guo Dr. Vincent H. B. Ho Dr. Vimalan Vijayaragavan Dr. Parasuraman Padmanabhan Prof. Kishore Bhakoo Prof. Subramanian Tamil Selvan 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(10):3914-3918
In this communication, we report the synthesis of small‐sized (<10 nm), water‐soluble, magnetic nanoparticles (MNPs) coated with polyhedral oligomeric silsesquioxanes (POSS), which contain either polyethylene glycol (PEG) or octa(tetramethylammonium) (OctaTMA) as functional groups. The POSS‐coated MNPs exhibit superparamagnetic behavior with saturation magnetic moments (51–53 emu g?1) comparable to silica‐coated MNPs. They also provide good colloidal stability at different pH and salt concentrations, and low cytotoxicity to MCF‐7 human breast epithelial cells. The relaxivity data and magnetic resonance (MR) phantom images demonstrate the potential application of these MNPs in bioimaging. 相似文献
52.
53.
V. A. Bespalov V. M. Glazov E. A. Il’ichev Yu. A. Klimov S. V. Kuklev A. E. Kuleshov R. M. Nabiev G. N. Petrukhin B. G. Potapov G. S. Rychkov D. S. Sokolov V. V. Fandeev E. A. Fetisov S. S. Yakushov 《Technical Physics》2015,60(4):553-560
The results of investigation of optical image detectors designed for the largest problem, near-VUV, range of the spectrum are presented. The possibility of using a dual-stage image detection system to appreciably lower the sensitivity threshold and make computer data processing feasible is considered. The integration of a UV module into a wideband image detector is studied. 相似文献
54.
55.
56.
57.
Elasasy M. E. A. Elnaggar D. H. Hafez N. A. Abdel Azab M. E. Amr A. E. Omran M. M. Mohamed A. M. 《Russian Journal of General Chemistry》2021,91(5):915-925
Russian Journal of General Chemistry - Some new fluoro-heterocyclic compounds containing thiazole and pyridine moities have been synthesized and studied for their antiproliferative activity.... 相似文献
58.
Colloid Journal - An Erratum to this paper has been published: https://doi.org/10.1134/S1061933X21330024 相似文献
59.
The biodegradability of phtalic acid esters in marine and freshwater environments was characterized by their binding free energy with corresponding degrading enzymes. According to comprehensive biodegradation effects weights, the binding free energy values were converted into dimensionless efficacy coefficient using ratio normalization method. Then, considering comprehensive dual biodegradation effects value and the structural parameters of PAEs in both marine and freshwater environments, a 3D-QSAR pharmacophore model was constructed, five PAE derivatives (DBP−COOH, DBP−CHO, DBP−OH, DINP−NH2, and DINP−NO2) were screened out based on their environmental friendliness, functionality and stability. The prediction of biodegradation effects on five PAE derivatives by biodegradation models in marine and freshwater environment increased by 15.90 %, 15.84 %, 27.21 %, 12.33 %, and 8.32 %, and 21.57 %, 15.21 %, 20.99 %, 15.10 %, and 9.74 %, respectively. By simulating the photodegradation path of the PAE derivative molecular, it was found that DBP−OH can generate .OH and provides free radicals for the photodegradation of microplastics in the environment. 相似文献
60.