全文获取类型
收费全文 | 150929篇 |
免费 | 21497篇 |
国内免费 | 16022篇 |
专业分类
化学 | 79629篇 |
晶体学 | 1244篇 |
力学 | 6340篇 |
综合类 | 715篇 |
数学 | 14016篇 |
物理学 | 42861篇 |
无线电 | 43643篇 |
出版年
2024年 | 581篇 |
2023年 | 3328篇 |
2022年 | 4453篇 |
2021年 | 5456篇 |
2020年 | 5479篇 |
2019年 | 5015篇 |
2018年 | 4689篇 |
2017年 | 4452篇 |
2016年 | 6279篇 |
2015年 | 6695篇 |
2014年 | 8199篇 |
2013年 | 10556篇 |
2012年 | 12342篇 |
2011年 | 12649篇 |
2010年 | 9328篇 |
2009年 | 9309篇 |
2008年 | 9723篇 |
2007年 | 8883篇 |
2006年 | 8385篇 |
2005年 | 7349篇 |
2004年 | 5524篇 |
2003年 | 4672篇 |
2002年 | 4201篇 |
2001年 | 3582篇 |
2000年 | 3222篇 |
1999年 | 3214篇 |
1998年 | 2749篇 |
1997年 | 2391篇 |
1996年 | 2388篇 |
1995年 | 2092篇 |
1994年 | 1835篇 |
1993年 | 1538篇 |
1992年 | 1368篇 |
1991年 | 1150篇 |
1990年 | 991篇 |
1989年 | 719篇 |
1988年 | 590篇 |
1987年 | 456篇 |
1986年 | 464篇 |
1985年 | 406篇 |
1984年 | 308篇 |
1983年 | 265篇 |
1982年 | 201篇 |
1981年 | 139篇 |
1980年 | 128篇 |
1979年 | 71篇 |
1978年 | 67篇 |
1977年 | 67篇 |
1976年 | 69篇 |
1973年 | 73篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
81.
Youchao Wang Na Tian Weize Sun Boerhan Rena Xusheng Guo Yang Feng Chao Li Xuesong Wang Qianxiong Zhou 《Particle & Particle Systems Characterization》2020,37(5):2000045
Photoactivated chemotherapy (PACT) has appealing merits over traditional chemotherapy as well as photodynamic therapy (PDT) by virtue of its spatial and temporal control on drug activity and oxygen-independent mechanisms of action. However, the short photoactivation wavelengths, e.g., visible light–activated Ru(II)-based PACT agents, limit the clinical application severely. In this work, a facile construction of supramolecular nanoparticles from a poly(ethylene glycol) (PEG)-modified [Ru(dip)2(py-SO3)]+ (abbreviated as Ru-PEG, dip = 4,7-diphenyl-1,10-phenanthroline, py-SO3 = pyridine-2-sulfonate) and 1,3-phenylenebis(pyren-1-ylmethanone) (BP) is shown. While Ru-PEG may undergo photoinduced ligand dissociation and release anticancer species of [Ru(dip)2(H2O)2]2+, BP has extremely large two-photon absorption cross sections (δ2) in the NIR region and intense fluorescence over the wavelengths where Ru-PEG has strong absorption. Thus, two-photon excitation of BP followed by an efficient Förster resonance energy transfer (FRET) from BP to Ru-PEG may lead to a potent inactivation against cisplatin-resistant cancer cells and 3D multicellular tumor spheroids (MCTSs). The residue fluorescence of BP also allows the cellular uptake of the particles to be visualized. This work provides a universal and convenient strategy to realize theranostic PACT in the ideal phototherapeutic window of 650–900 nm. 相似文献
82.
Da Hyeon Choi Jiwon Park Ju Kwang Choi Kyeong Eun Lee Won Hee Lee Jinho Yang Ju Yeon Lee Yoon Jeong Park Chan Oh Ho-Ryun Won Bon Seok Koo Jae Won Chang Yoon Shin Park 《Experimental & molecular medicine》2020,52(9):1564
Oral microbes have the capacity to spread throughout the gastrointestinal system and are strongly associated with multiple diseases. Given that tonsils are located between the oral cavity and the laryngopharynx at the gateway of the alimentary and respiratory tracts, tonsillar tissue may also be affected by microbiota from both the oral cavity (saliva) and the alimentary tract. Here, we analyzed the distribution and association of the microbial communities in the saliva and tonsils of Korean children subjected to tonsillectomy because of tonsil hyperplasia (n = 29). The microbiome profiles of saliva and tonsils were established via 16S rRNA gene sequencing. Based on the alpha diversity indices, the microbial communities of the two groups showed high similarities. According to Spearman’s ranking correlation analysis, the distribution of Treponema, the causative bacterium of periodontitis, in saliva and tonsils was found to have a significant positive correlation. Two representative microbes, Prevotella in saliva and Alloprevotella in tonsils, were negatively correlated, while Treponema 2 showed a strong positive correlation between saliva and tonsils. Taken together, strong similarities in the microbial communities of the tonsils and saliva are evident in terms of diversity and composition. The saliva microbiome is expected to significantly affect the tonsil microbiome. Furthermore, we suggest that our study creates an opportunity for tonsillar microbiome research to facilitate the development of novel microbiome-based therapeutic strategies.Subject terms: Comparative genomics, Metagenomics 相似文献
83.
84.
Tuning the Basicity of Cyano‐Containing Ionic Liquids to Improve SO2 Capture through Cyano–Sulfur Interactions 下载免费PDF全文
Dr. Guokai Cui Fengtao Zhang Xiuyuan Zhou Prof. Haoran Li Prof. Jianji Wang Prof. Congmin Wang 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(14):5632-5639
A new approach has been developed to improve SO2 sorption by cyano‐containing ionic liquids (ILs) through tuning the basicity of ILs and cyano–sulfur interaction. Several kinds of cyano‐containing ILs with different basicity were designed, prepared, and used for SO2 capture. The interaction between these cyano‐containing ILs and SO2 was investigated by FTIR and NMR methods. Spectroscopic investigations and quantum chemical calculations showed that dramatic effects on SO2 capacity originate from the basicity of the ILs and enhanced cyano–sulfur interaction. Furthermore, the captured SO2 was easy to release by heating or bubbling N2 through the ILs. This efficient and reversible process, achieved by tuning the basicity of ILs, is an excellent alternative to current technologies for SO2 capture. 相似文献
85.
86.
Guo Yan Li Zhuang Wei Yuxi Zhang Xinxu Shi Kexin 《Journal of Solid State Electrochemistry》2022,26(4):1051-1065
Journal of Solid State Electrochemistry - Polyvinylpyrrolidone (PVP) and graphene (G)-modified iron oxides (Fe2O3-PVP-G) are prepared by a simple hydrothermal reaction. Their morphology and... 相似文献
87.
88.
The Ramanujan Journal - Inspired by Andrews and Merca’s recent work on the number of even parts over all partitions into distinct parts, we introduce a new kind of Beck type identities, which... 相似文献
89.
90.
Chi-Kwong Li Ming-Cheng Tsai Ya-Shu Wang Ngai-Ching Wong 《Journal of Mathematical Analysis and Applications》2022,505(2):125522
Let L be an additive map between (real or complex) matrix algebras sending Hermitian idempotent matrices to Hermitian idempotent matrices. We show that there are nonnegative integers with and an unitary matrix U such that We also extend this result to the (complex) von Neumann algebra setting, and provide a supplement to the Dye-Bunce-Wright Theorem asserting that every additive map of Hermitian idempotents extends to a Jordan ?-homomorphism. 相似文献