全文获取类型
收费全文 | 256篇 |
免费 | 18篇 |
国内免费 | 50篇 |
专业分类
化学 | 172篇 |
晶体学 | 2篇 |
力学 | 17篇 |
综合类 | 4篇 |
数学 | 19篇 |
物理学 | 110篇 |
出版年
2023年 | 6篇 |
2022年 | 9篇 |
2021年 | 5篇 |
2020年 | 9篇 |
2019年 | 6篇 |
2018年 | 10篇 |
2017年 | 6篇 |
2016年 | 8篇 |
2015年 | 8篇 |
2014年 | 16篇 |
2013年 | 24篇 |
2012年 | 21篇 |
2011年 | 18篇 |
2010年 | 9篇 |
2009年 | 19篇 |
2008年 | 15篇 |
2007年 | 14篇 |
2006年 | 21篇 |
2005年 | 14篇 |
2004年 | 11篇 |
2003年 | 5篇 |
2002年 | 2篇 |
2001年 | 6篇 |
2000年 | 4篇 |
1999年 | 6篇 |
1998年 | 5篇 |
1997年 | 3篇 |
1996年 | 7篇 |
1995年 | 1篇 |
1994年 | 5篇 |
1993年 | 6篇 |
1992年 | 4篇 |
1991年 | 3篇 |
1990年 | 5篇 |
1989年 | 3篇 |
1988年 | 2篇 |
1987年 | 2篇 |
1986年 | 3篇 |
1985年 | 2篇 |
1982年 | 1篇 |
排序方式: 共有324条查询结果,搜索用时 15 毫秒
1.
Wang Yingying Wang Donghui Shu Weiqing Sha Jingquan Zhang Haifeng 《Transition Metal Chemistry》2020,45(4):245-251
Transition Metal Chemistry - Two cubane-like complexes, namely [Ni4L4(HOEt)4] (1), [Co4L4(HOEt)4] (2) (H2L?=?(E)-2-((3-hydroxypropylimino)methyl)-6-methoxyphenol), were prepared under... 相似文献
2.
Weiqing Xu Yu Wu Yuling Xu Dr. Xiaoli Cai Prof. Wenling Gu Prof. Chengzhou Zhu 《Angewandte Chemie (International ed. in English)》2023,62(47):e202308827
Enzymatic catalysis with high efficiency allows them a great prospect in metabolite monitoring in living cells. However, complex tumor microenvironments, such as acidity, H2O2, and hypoxia, are bound to disturb catalytic reactions for misleading results. Here, we report a spatially compartmentalized artificial organelle to correct intratumoral glucose analysis, where the zeolitic imidazolate framework-8 immobilized glucose oxidase-horseradish peroxidase cascade core and catalase-directed shell act as signal transduction and guarding rooms respectively. The acid-digested core and stable shell provide appropriate spaces to boost biocatalytic efficiency with good tolerability. Notably, the endogenous H2O2 is in situ decomposed to O2 by catalase, which not only overcomes the interference in signal output but also alleviates the hypoxic states to maximize glucose oxidation. The marked protective effect and biocompatibility render artificial organelles to correct the signal transduction for dynamic monitoring glucose in vitro and in vivo, achieving our goal of accurate intratumoral metabolite analysis. 相似文献
3.
Vacuum Ultraviolet Free-Electron Laser Photoionization Mass Spectrometry of Alpha-pinene Ozonolysis 下载免费PDF全文
Xiangyu Zang Zhaoyan Zhang Chong Wang Tiantong Wang Huijun Zheng Hua Xie Jiayue Yang Dongxu Dai Guorong Wu Weiqing Zhang Gang Li Xueming Yang Ling Jiang 《化学物理学报(中文版)》2022,35(2):281-288
4.
Xiaolong Wan Jiadong Hu Dongyang Xu Yang Shang Yanxia Zhen Chenchen Hu Fan Xiao Yu-Peng He Yisheng Lai Weiqing Xie 《Tetrahedron letters》2017,58(12):1090-1093
A Re2O7 catalyzed cycloetherification of monoallylic diols is described. The reaction features short reaction time, mild reaction conditions and exclusive E selectivity. A wide range of monoallylic alcohols with alkyl or aryl substituents on olefin smoothly undergo ring closure to deliver corresponding oxa-heterocycles. The reaction is also operationally simple and not sensitive to air and moisture. 相似文献
5.
纳米酶因其经济、 稳定、 性质可调和可循环利用等诸多优势, 成功地克服了天然酶在实际应用中的不足. 单原子材料的出现使得对纳米酶的研究迈入原子水平, 其较高的原子利用率、 独特的配位环境和较强的金属-载体相互作用为揭示纳米酶构效关系及调控类酶活性提供了可能. 本文总结了近年来单原子材料类酶催化的研究进展, 重点讨论了单原子材料类酶活性的调控策略和催化机理, 概述了单原子类酶材料在癌症治疗、 抗氧化治疗、 抗菌以及生物传感等方面的应用, 并对单原子类酶材料的发展前景进行了展望. 相似文献
6.
7.
回火温度对40Cr钢疲劳裂纹萌生寿命的影响 总被引:2,自引:0,他引:2
用系统分析的方法,通过三点弯曲疲劳试验,以数值描述的方式,在线跟踪了40Cr钢及其在三种回火温度下疲劳裂纹萌生过程的疲劳损伤,实验结果表明:随着回火处理温度的提高,40Cr钢的疲劳裂纹萌生寿命都有不同程度的提高.但裂纹萌生寿命在低于450℃的温度范围里,随着回火温度的提高,裂纹萌生寿命有明显的提高,在450℃至580℃范围内,随回火温度的上升,裂纹萌生寿命则没有明显的增加. 相似文献
8.
9.
This paper introduces the geometric assumptions and neglects of the pore size distribution calculated by BJH method, the arithmetic approximation for simplified calculation, the derivation process of each parameter, the calculation steps and key points of the pore size distribution. This paper also introduces the application scope of BJH method at the current instrument level, and how to further integrate the data. In order to get the required analysis and test report, references are provided for the subsequent adjustment of test parameters and improvement of test methods. Some problems often encountered in reading experimental reports are also discussed. 相似文献
10.
A eigenspace-based source number estimation was presented.It projects the estimated covariance matrix of array signal into signal eigen-subspace and noise eigen-subspace, respectively.Using the orthogonality between signal eigen-subspace and noise eigen-subspace, it is easy to differentiate the contribution of signal and noise by using the criterion value,or the magnitude of projection.Like the Direction-of-Arrival(DOA) estimation algorithm,the estimator uses the eigenvalue decomposition of covariance matrix with order M×M,where M is the number of elements,and hence can save much computational burden.To reduce more computational burden,the estimation can be implemented by the decomposition in the real-value space.Computer simulation demonstrates the distribution of criterion value and the performance of the estimation method.The estimation method was also tested with the sonar data,which shows good performances. 相似文献