全文获取类型
收费全文 | 22850篇 |
免费 | 4307篇 |
国内免费 | 3167篇 |
专业分类
化学 | 16968篇 |
晶体学 | 251篇 |
力学 | 1256篇 |
综合类 | 236篇 |
数学 | 2726篇 |
物理学 | 8887篇 |
出版年
2024年 | 24篇 |
2023年 | 479篇 |
2022年 | 561篇 |
2021年 | 790篇 |
2020年 | 1032篇 |
2019年 | 1140篇 |
2018年 | 878篇 |
2017年 | 825篇 |
2016年 | 1190篇 |
2015年 | 1223篇 |
2014年 | 1452篇 |
2013年 | 1788篇 |
2012年 | 2180篇 |
2011年 | 2199篇 |
2010年 | 1581篇 |
2009年 | 1498篇 |
2008年 | 1602篇 |
2007年 | 1408篇 |
2006年 | 1245篇 |
2005年 | 1001篇 |
2004年 | 797篇 |
2003年 | 650篇 |
2002年 | 717篇 |
2001年 | 609篇 |
2000年 | 434篇 |
1999年 | 496篇 |
1998年 | 369篇 |
1997年 | 296篇 |
1996年 | 272篇 |
1995年 | 233篇 |
1994年 | 201篇 |
1993年 | 211篇 |
1992年 | 151篇 |
1991年 | 146篇 |
1990年 | 124篇 |
1989年 | 114篇 |
1988年 | 92篇 |
1987年 | 56篇 |
1986年 | 51篇 |
1985年 | 55篇 |
1984年 | 34篇 |
1983年 | 27篇 |
1982年 | 27篇 |
1981年 | 13篇 |
1980年 | 5篇 |
1979年 | 8篇 |
1978年 | 6篇 |
1977年 | 5篇 |
1976年 | 4篇 |
1972年 | 4篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
21.
22.
Covalent organic frameworks(COFs) are emerging photocatalysts for hydrogen evolution in water splitting in recent years. They offer a pre-designable platform to design tailor-made structures and chemically adjustable functionality in terms of photocatalysis. In this review, we summarize the recent striking progress of COF-based photocatalysts in design and synthesis. Firstly, different approaches to functionalizing building blocks, diversifying linkages, extending π-conjugation and establishing D-A conjugation are illustrated for enhancing photocatalytic activity. Next, post-modification of backbones and pores is detailed for emphasizing the synergistic catalytic uniqueness of COFs. Besides, the strategy of preparing COF-related composites with various semiconductors is outlined for optimizing the electronic properties. Finally, we conclude with the current challenges and promising opportunities for the exploration of new COF-based photocatalysts. 相似文献
23.
将一种人工合成的无机聚合物——蒙脱石皂石黏土(smectite,Sm)应用于基质辅助激光解吸电离飞行时间质谱分析(matrix-assisted laser desorption/ionization time of flight mass spectrometry, MALDI-TOF-MS),以检测糖类化合物。 将传统的有机基质2,4,6-三羟基苯乙酮(trihydroxyacetophenone, THAP)与阳离子交换后的皂石黏土混合制备成新型复合基质,应用于糖类化合物的检测。通过比较不同的制样方法,测定不同分子直径的糖类化合物,发现由于受复合基质晶面间距的限制,只有小分子糖类化合物能进入晶面间隙充分接触有机基质并被离子化,从而实现对小分子糖类化合物的选择性检测。 相似文献
24.
Sun Yuan Luo Shunlong Lei Xiangyun 《International Journal of Theoretical Physics》2021,60(9):3211-3224
International Journal of Theoretical Physics - Gram matrices arise naturally in the consideration of pair-wise overlap of a family of vectors or quantum pure states, and play an important role in... 相似文献
25.
Acta Mathematicae Applicatae Sinica, English Series - This paper proposes a method for modelling volatilities (conditional covariance matrices) of high dimensional dynamic data. We combine the... 相似文献
26.
27.
The Ramanujan Journal - We obtain a combinatorial formula related to the shear transformation for semi-invariants of binary forms, which implies the classical characterization of semi-invariants in... 相似文献
28.
Jia Tian-Cong Guo Jin-Tao Wang Zhen Zhu Xiao-Shan Zhang Qian-Xin Chen Ping Yao Kun Lv Wen-Ying Liu Guo-Guang 《Journal of Radioanalytical and Nuclear Chemistry》2019,321(3):823-829
Journal of Radioanalytical and Nuclear Chemistry - In the present work the final products of coumarin radiation chemical transformation are investigated by chromatography. During radiolysis of... 相似文献
29.
Wu Peng Wang Yun Li Yang Hu Xuewen Xiu Taoyuan Yuan Dingzhong Liu Yan Wu Zhenyu Liu Zhirong 《Journal of Radioanalytical and Nuclear Chemistry》2019,322(2):553-559
Journal of Radioanalytical and Nuclear Chemistry - In order to reduce the potential toxicity to the environment after treatment of radioactive waste water, an eco-friendly graphene oxide... 相似文献
30.
By 5-h reaction of cis-[RuIICl2(DMSO)4] (M2) with K10[α2-P2W17O61] (M3) in ice-cooled, HCl-acidic aqueous solution, a water-soluble 1:2-type diamagnetic ruthenium(II) complex of formula K18[RuII(DMSO)2(P2W17O61)2]·35H2O (M1) was unexpectedly obtained as an analytically pure, homogeneous tan-colored solid, in which two DMSO ligands are coordinated to the ruthenium(II) atom. The cytotoxic potential of the complex was tested on C33A, DLD-1, and HepG-2 cancer cells and human normal embryonic lung fibroblasts cell MRC-5; the viability of the treated cells was evaluated by MTT assay. The mode of cell death was assessed by morphological study of DNA damage and apoptosis assays. Compound M1 induced cell death in a dose-dependent manner, and the mode of cell death was essentially apoptosis though necrosis was also noticed. Cell cycle analysis by flow cytometry indicated that M1 caused cell cycle arrest and accumulated cells in S phase. 相似文献