全文获取类型
收费全文 | 63188篇 |
免费 | 10390篇 |
国内免费 | 8688篇 |
专业分类
化学 | 46114篇 |
晶体学 | 912篇 |
力学 | 3707篇 |
综合类 | 620篇 |
数学 | 7458篇 |
物理学 | 23455篇 |
出版年
2024年 | 177篇 |
2023年 | 1060篇 |
2022年 | 2024篇 |
2021年 | 2125篇 |
2020年 | 2278篇 |
2019年 | 2358篇 |
2018年 | 2051篇 |
2017年 | 2073篇 |
2016年 | 2835篇 |
2015年 | 3017篇 |
2014年 | 3666篇 |
2013年 | 4764篇 |
2012年 | 5599篇 |
2011年 | 5867篇 |
2010年 | 4239篇 |
2009年 | 4279篇 |
2008年 | 4699篇 |
2007年 | 4063篇 |
2006年 | 3706篇 |
2005年 | 3102篇 |
2004年 | 2387篇 |
2003年 | 1979篇 |
2002年 | 1974篇 |
2001年 | 1623篇 |
2000年 | 1348篇 |
1999年 | 1166篇 |
1998年 | 938篇 |
1997年 | 829篇 |
1996年 | 814篇 |
1995年 | 665篇 |
1994年 | 654篇 |
1993年 | 561篇 |
1992年 | 495篇 |
1991年 | 415篇 |
1990年 | 364篇 |
1989年 | 277篇 |
1988年 | 242篇 |
1987年 | 188篇 |
1986年 | 209篇 |
1985年 | 198篇 |
1984年 | 123篇 |
1983年 | 92篇 |
1982年 | 83篇 |
1981年 | 67篇 |
1980年 | 60篇 |
1979年 | 76篇 |
1978年 | 47篇 |
1977年 | 43篇 |
1974年 | 45篇 |
1973年 | 50篇 |
排序方式: 共有10000条查询结果,搜索用时 20 毫秒
21.
22.
Jie Lu Ju-Kang Wu Yao Jiang Dr. Peng Tan Lin Zhang Yu Lei Prof. Xiao-Qin Liu Prof. Lin-Bing Sun 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(16):6490-6496
Hierarchically porous metal–organic frameworks (HP-MOFs) are promising in various applications. Most reported HP-MOFs are prepared based on the generation of mesopores in microporous frameworks, and the formed mesopores are connected by microporous channels, limiting the accessibility of mesopores for bulky molecules. A hierarchical structure is formed by constructing microporous MOFs in uninterrupted mesoporous tunnels. Using the confined space in as-prepared mesoporous silica, highly dispersed metal precursors for MOFs are coated on the internal surface of mesoporous tunnels. Ligand vapor-induced crystallization is employed to enable quantitative formation of MOFs in situ, in which sublimated ligands diffuse into mesoporous tunnels and react with metal precursors. The obtained hierarchically porous composites exhibit record-high adsorption capacity for the bulky molecule trypsin. The thermal and storage stability of trypsin is improved upon immobilization on the composites. 相似文献
23.
24.
Synthesis of Small‐Sized,Porous, and Low‐Toxic Magnetite Nanoparticles by Thin POSS Silica Coating
下载免费PDF全文
![点击此处可从《Chemistry (Weinheim an der Bergstrasse, Germany)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
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
25.
26.
在中国科学技术大学夏季学期的研究型实验课程"化学科研基础训练"中开设"壳聚糖的制备与表征"综合实验,以龙虾壳为原料,通过除蛋白、脱盐、脱色、脱乙酰等一系列反应,制备得到目标产物壳聚糖。运用红外光谱、核磁共振仪、黏度法、滴定等对产品的结构及性能进行表征。 相似文献
27.
Single Crystal to Single Crystal (SC‐to‐SC) Transformation from a Nonporous to Porous Metal–Organic Framework and Its Application Potential in Gas Adsorption and Suzuki Coupling Reaction through Postmodification
下载免费PDF全文
![点击此处可从《Chemistry (Weinheim an der Bergstrasse, Germany)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Dr. Rupam Sen Debraj Saha Dr. Subratanath Koner Dr. Paula Brandão Dr. Zhi Lin 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(15):5962-5971
A new amino‐functionalized strontium–carboxylate‐based metal–organic framework (MOF) has been synthesized that undergoes single crystal to single crystal (SC‐to‐SC) transformation upon desolvation. Both structures have been characterized by single‐crystal X‐ray analysis. The desolvated structure shows an interesting 3D porous structure with pendent ?NH2 groups inside the pore wall, whereas the solvated compound possesses a nonporous structure with DMF molecules on the metal centers. The amino group was postmodified through Schiff base condensation by pyridine‐2‐carboxaldehyde and palladium was anchored on that site. The modified framework has been utilized for the Suzuki cross‐coupling reaction. The compound shows high activity towards the C?C cross‐coupling reaction with good yields and turnover frequencies. Gas adsorption studies showed that the desolvated compound had permanent porosity and was microporous in nature with a BET surface area of 2052 m2 g?1. The material also possesses good CO2 (8 wt %) and H2 (1.87 wt %) adsorption capabilities. 相似文献
28.
29.
30.