全文获取类型
收费全文 | 7347篇 |
免费 | 189篇 |
国内免费 | 213篇 |
专业分类
化学 | 3539篇 |
晶体学 | 27篇 |
力学 | 82篇 |
综合类 | 29篇 |
数学 | 2313篇 |
物理学 | 1759篇 |
出版年
2023年 | 16篇 |
2022年 | 82篇 |
2021年 | 71篇 |
2020年 | 178篇 |
2019年 | 361篇 |
2018年 | 123篇 |
2017年 | 338篇 |
2016年 | 123篇 |
2015年 | 140篇 |
2014年 | 168篇 |
2013年 | 335篇 |
2012年 | 277篇 |
2011年 | 492篇 |
2010年 | 318篇 |
2009年 | 563篇 |
2008年 | 603篇 |
2007年 | 528篇 |
2006年 | 544篇 |
2005年 | 373篇 |
2004年 | 273篇 |
2003年 | 239篇 |
2002年 | 245篇 |
2001年 | 196篇 |
2000年 | 154篇 |
1999年 | 103篇 |
1998年 | 106篇 |
1997年 | 124篇 |
1996年 | 127篇 |
1995年 | 72篇 |
1994年 | 62篇 |
1993年 | 35篇 |
1992年 | 35篇 |
1991年 | 32篇 |
1990年 | 16篇 |
1989年 | 17篇 |
1988年 | 11篇 |
1987年 | 14篇 |
1986年 | 15篇 |
1985年 | 24篇 |
1984年 | 21篇 |
1983年 | 13篇 |
1982年 | 10篇 |
1981年 | 27篇 |
1980年 | 24篇 |
1979年 | 26篇 |
1978年 | 26篇 |
1977年 | 20篇 |
1976年 | 11篇 |
1974年 | 10篇 |
1973年 | 14篇 |
排序方式: 共有7749条查询结果,搜索用时 171 毫秒
11.
12.
WEI Qi-cai 《高校应用数学学报(英文版)》2015,(2):217-226
In this paper, with the aid of large deviation formulas established in strong topology of functional space generated by H¨older norm, we discuss the functional sample path properties of subsequence's C-R increments for a Wiener process in H¨older normThe obtained results,generalize the corresponding results of Chen and the classic Strassen's law of iterated logarithm for a Wiener process. 相似文献
13.
14.
Bingjie Chen Dr. Lianhai Zu Dr. Yao Liu Dr. Ruijing Meng Yutong Feng Prof. Chengxin Peng Feng Zhu Tianzi Hao Jiajia Ru Prof. Yonggang Wang Prof. Jinhu Yang 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(8):3161-3166
Incorporating nanoscale Si into a carbon matrix with high dispersity is desirable for the preparation of lithium-ion batteries (LIBs) but remains challenging. A space-confined catalytic strategy is proposed for direct superassembly of Si nanodots within a carbon (Si NDs⊂C) framework by copyrolysis of triphenyltin hydride (TPT) and diphenylsilane (DPS), where Sn atomic clusters created from TPT pyrolysis serve as the catalyst for DPS pyrolysis and Si catalytic growth. The use of Sn atomic cluster catalysts alters the reaction pathway to avoid SiC generation and enable formation of Si NDs with reduced dimensions. A typical Si NDs⊂C framework demonstrates a remarkable comprehensive performance comparable to other Si-based high-performance half LIBs, and higher energy densities compared to commercial full LIBs, as a consequence of the high dispersity of Si NDs with low lithiation stress. Supported by mechanic simulations, this study paves the way for construction of Si/C composites suitable for applications in future energy technologies. 相似文献
15.
A Quantitative Model for Alkane Nucleophilicity Based on C−H Bond Structural/Topological Descriptors
16.
Dawei Chen Ridao Chen Ruishan Wang Jianhua Li Kebo Xie Chuancai Bian Lili Sun Xiaolin Zhang Jimei Liu Lin Yang Fei Ye Xiaoming Yu Jungui Dai 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2015,127(43):12869-12873
The catalytic promiscuity of the novel benzophenone C‐glycosyltransferase, MiCGT, which is involved in the biosynthesis of mangiferin from Mangifera indica, was explored. MiCGT exhibited a robust capability to regio‐ and stereospecific C‐glycosylation of 35 structurally diverse druglike scaffolds and simple phenolics with UDP‐glucose, and also formed O‐ and N‐glycosides. Moreover, MiCGT was able to generate C‐xylosides with UDP‐xylose. The OGT‐reversibility of MiCGT was also exploited to generate C‐glucosides with simple sugar donor. Three aryl‐C‐glycosides exhibited potent SGLT2 inhibitory activities with IC50 values of 2.6×, 7.6×, and 7.6×10−7 M , respectively. These findings demonstrate for the first time the significant potential of an enzymatic approach to diversification through C‐glycosidation of bioactive natural and unnatural products in drug discovery. 相似文献
17.
18.
19.
Jie Li Prof. Dr. Shuanglin Qu Prof. Dr. Wanxiang Zhao 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(6):2380-2384
A rhodium-catalyzed remote C(sp3)−H borylation of silyl enol ethers (SEEs, E/Z mixtures) by alkene isomerization and hydroboration is reported. The reaction exhibits mild reaction conditions and excellent functional-group tolerance. This method is compatible with an array of SEEs, including linear and branched SEEs derived from aldehydes and ketones, and provides direct access to a broad range of structurally diverse 1,n-borylethers in excellent regioselectivities and good yields. These compounds are precursors to various valuable chemicals, such as 1,n-diols and aminoalcohols. 相似文献
20.
N. Sharadhi S. Vimala K. Nurjahan B. N. Veerabhadraswamy C. V. Yelamaggad 《Liquid crystals》2020,47(2):211-218
ABSTRACT Blue phase liquid crystals are soft 3D photonic crystals in which the liquid crystal molecules self-assemble to form a cubic structure with lattice spacing of a few hundred nanometers resulting in selective reflection of colours in the visible spectrum. The corresponding wavelength or the ‘photonic band gap’ can be tuned using various external stimuli such as thermal, electric, magnetic and optical fields. Here, we report efficient tuning of photonic band gap by utilising the combination of electric and optical fields in a blue phase liquid crystalline system. The studies indicate that the chirality of the medium has a direct bearing on the direction of the wavelength shift and the extent of the photonic band gap tunability. More importantly, the synergistic effect of the two fields helps in reversible tuning of the band gap. 相似文献