全文获取类型
收费全文 | 501篇 |
免费 | 25篇 |
国内免费 | 53篇 |
专业分类
化学 | 432篇 |
晶体学 | 2篇 |
力学 | 19篇 |
综合类 | 4篇 |
数学 | 44篇 |
物理学 | 78篇 |
出版年
2024年 | 2篇 |
2023年 | 16篇 |
2022年 | 11篇 |
2021年 | 23篇 |
2020年 | 16篇 |
2019年 | 21篇 |
2018年 | 27篇 |
2017年 | 5篇 |
2016年 | 9篇 |
2015年 | 8篇 |
2014年 | 13篇 |
2013年 | 27篇 |
2012年 | 34篇 |
2011年 | 50篇 |
2010年 | 22篇 |
2009年 | 23篇 |
2008年 | 36篇 |
2007年 | 43篇 |
2006年 | 39篇 |
2005年 | 24篇 |
2004年 | 12篇 |
2003年 | 7篇 |
2002年 | 9篇 |
2001年 | 10篇 |
2000年 | 10篇 |
1999年 | 8篇 |
1998年 | 9篇 |
1997年 | 10篇 |
1996年 | 10篇 |
1995年 | 10篇 |
1994年 | 9篇 |
1993年 | 8篇 |
1992年 | 5篇 |
1991年 | 2篇 |
1990年 | 3篇 |
1988年 | 2篇 |
1985年 | 2篇 |
1984年 | 3篇 |
1983年 | 1篇 |
排序方式: 共有579条查询结果,搜索用时 15 毫秒
471.
The reaction of aminoketal[60]fullerene peroxide with pyrrolidine removes all the peroxo groups giving the aminooxahomo[60]fullerene derivatives with five amino addends together with one hydroxyl, one epoxy and three ether moieties. The structure has been determined by spectroscopic data and single crystal X-ray analysis. 相似文献
472.
A Size‐Reducible Nanodrug with an Aggregation‐Enhanced Photodynamic Effect for Deep Chemo‐Photodynamic Therapy
下载免费PDF全文
![点击此处可从《Angewandte Chemie (International ed. in English)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Chendong Ji Qin Gao Xinghua Dong Prof. Wenyan Yin Prof. Zhanjun Gu Prof. Zhihua Gan Prof. Yuliang Zhao Prof. Meizhen Yin 《Angewandte Chemie (International ed. in English)》2018,57(35):11384-11388
Fluorescent dyes with multi‐functionality are of great interest for photo‐based cancer theranostics. However, their low singlet oxygen quantum yield impedes their potential applications for photodynamic therapy (PDT). Now, a molecular self‐assembly strategy is presented for a nanodrug with a remarkably enhanced photodynamic effect based on a dye‐chemodrug conjugate. The self‐assembled nanodrug possesses an increased intersystem crossing rate owing to the aggregation of dye, leading to a distinct singlet oxygen quantum yield (Φ(1O2)). Subsequently, upon red light irradiation, the generated singlet oxygen reduces the size of the nanodrug from 90 to 10 nm, which facilitates deep tumor penetration of the nanodrug and release of chemodrug. The nanodrug achieved in situ tumor imaging and potent tumor inhibition by deep chemo‐PDT. Our work verifies a facile and effective self‐assembly strategy to construct nanodrugs with enhanced performance for cancer theranostics. 相似文献
473.
We described herein a new AIE-active polymer sensor incorporating triazole moiety for Hg2+ detection in aqueous solution. The polymer sensor P1 was synthesized from tetraphenylethene and diazidobenzene via click reaction. It shows typical AIE feature, and emits cyan fluorescence in the mixture of tetrahydrofuran and water, reaching the strongest fluorescence when the fraction of water (fw) is 90%. In aqueous solution (fw?=?90%), the polymer sensor can exhibit fluorescence quenching response towards Hg2+ over other competing metal ions, with the fluorescence color changed from cyan to almost no emission, which can be clearly observed by the naked eyes under 365?nm UV lamp. 相似文献
474.
沈玉良 《数学年刊A辑(中文版)》2003,(2)
讨论了在实值调和函数所组成的Dirichlet空间上由拟对称同胚给出的拉回算子,并回答Schober(见[15])关于一些区域泛函的有关问题. 相似文献
475.
Deqin Fan Junpo He Jiangtao Xu Wei Tang Yang Liu Yuliang Yang 《Journal of polymer science. Part A, Polymer chemistry》2006,44(7):2260-2269
Copolymerization of styrene and acrylonitrile was carried out via reversible addition‐fragmentation chain transfer process (RAFT) in the presence of cumyl dithiobenzoate with AIBN as initiator. Copolymerization proceeded in a controlled/“living” fashion, and the copolymer composition depended on the feed ratio of monomer pairs. Block copolymers comprising styrene and acrylonitrile (SAN) segments and various functional blocks were synthesized through chain extension using the first blocks as macromolecular chain transfer agents (macroCTAs). Since the polymerization of both blocks proceeded through the RAFT process, the resulting block copolymers exhibited relatively narrow molecular weight distribution, with polydispersity indices in the range of 1.29–1.46. Gel permeation chromatography (GPC), and 1H NMR and FTIR measurements confirmed the successful synthesis of the functionalized block copolymers. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 2260–2269, 2006 相似文献
476.
Depth maps obtained through sensors are often unsatisfactory because of their low-resolution and noise interference. In this paper, we propose a real-time depth map enhancement system based on a residual network which uses dual channels to process depth maps and intensity maps respectively and cancels the preprocessing process, and the algorithm proposed can achieve real-time processing speed at more than 30 fps. Furthermore, the FPGA design and implementation for depth sensing is also introduced. In this FPGA design, intensity image and depth image are captured by the dual-camera synchronous acquisition system as the input of neural network. Experiments on various depth map restoration shows our algorithms has better performance than existing LRMC, DE-CNN and DDTF algorithms on standard datasets and has a better depth map super-resolution, and our FPGA completed the test of the system to ensure that the data throughput of the USB 3.0 interface of the acquisition system is stable at 226 Mbps, and support dual-camera to work at full speed, that is, 54 fps@ (1280 × 960 + 328 × 248 × 3). 相似文献
477.
本文通过实验对曲棍球击球技术进行了动力学分析.计算结果表明,击球动作的不确定性对其影响不大。文中使用的实验方法和计算公式适用于其它一些击球类运动. 相似文献
478.
Copper‐Catalyzed Radical/Radical CH/PH Cross‐Coupling: α‐Phosphorylation of Aryl Ketone O‐Acetyloximes
下载免费PDF全文
![点击此处可从《Angewandte Chemie (International ed. in English)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Jie Ke Yuliang Tang Hong Yi Yali Li Yongde Cheng Chao Liu Prof. Aiwen Lei 《Angewandte Chemie (International ed. in English)》2015,54(22):6604-6607
The selective radical/radical cross‐coupling of two different organic radicals is a great challenge due to the inherent activity of radicals. In this paper, a copper‐catalyzed radical/radical C? H/P? H cross‐coupling has been developed. It provides a radical/radical cross‐coupling in a selective manner. This work offers a simple way toward β‐ketophosphonates by oxidative coupling of aryl ketone o‐acetyloximes with phosphine oxides using CuCl as catalyst and PCy3 as ligand in dioxane under N2 atmosphere at 130 °C for 5 h, and yields ranging from 47 % to 86 %. The preliminary mechanistic studies by electron paramagnetic resonance (EPR) showed that, 1) the reduction of ketone o‐acetyloximes generates iminium radicals, which could isomerize to α‐sp3‐carbon radical species; 2) phosphorus radicals were generated from the oxidation of phosphine oxides. Various aryl ketone o‐acetyloximes and phosphine oxides were suitable for this transformation. 相似文献
479.
Changxi Li Junpo He Yanwu Zhou Yuankai Gu Yuliang Yang 《Journal of polymer science. Part A, Polymer chemistry》2011,49(6):1351-1360
Radical‐induced oxidation of reversible addition‐fragmentation chain transfer (RAFT) agents is investigated with respect to the effect of molecular structure on oxidation rate. The radicals are generated by homolysis of either azobisisobutyronitrile or alkoxyamine and transformed in situ immediately into peroxy radicals through transfer to molecular oxygen. It is found that the oxidation rate depends on the structure of Z‐ and R‐group of thiocarbonylthio compounds. For dithioesters with identical Z‐phenyl substituent, the oxidation rate decreases in the order of cyanoisopropyl (? C(Me)2CN) > cumyl (? C(Me)2Ph) > phenylethyl (? CH(Me)Ph) > 2‐methoxy‐1‐methyl‐2‐oxoethyl (? CH(Me) ? C(?O)OCH3) > benzyl (? CH2Ph). For dithioesters with identical R‐group, the oxidation rate decreases in the order of Z = phenyl? ~ benzyl? > RS? (trithiocarbonates) > RO? (xanthates). The stability of the RAFT agents toward oxidation correlates well with the chain transfer abilities as those previously reported by Rizzardo and coworkers. The priority of the oxidation reaction over the RAFT process, and the subsequent influence on RAFT polymerization are also investigated. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011 相似文献
480.
Ren Cai Dr. Yaping Du Wenyu Zhang Huiteng Tan Tao Zeng Xin Huang Hongfen Yang Chunping Chen Hai Liu Jixin Zhu Shengjie Peng Jing Chen Prof. Yuliang Zhao Prof. Haichen Wu Prof. Yizhong Huang Prof. Rong Xu Prof. Tuti Mariana Lim Prof. Qichun Zhang Prof. Hua Zhang Prof. Qingyu Yan 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(5):1568-1572