全文获取类型
收费全文 | 244928篇 |
免费 | 19211篇 |
国内免费 | 648篇 |
专业分类
化学 | 155134篇 |
晶体学 | 3388篇 |
力学 | 11157篇 |
综合类 | 5篇 |
数学 | 25051篇 |
物理学 | 70052篇 |
出版年
2023年 | 4276篇 |
2022年 | 2525篇 |
2021年 | 4028篇 |
2020年 | 6203篇 |
2019年 | 4192篇 |
2018年 | 4899篇 |
2017年 | 3173篇 |
2016年 | 9081篇 |
2015年 | 7556篇 |
2014年 | 8326篇 |
2013年 | 14006篇 |
2012年 | 10289篇 |
2011年 | 9724篇 |
2010年 | 9322篇 |
2009年 | 9084篇 |
2008年 | 8890篇 |
2007年 | 8790篇 |
2006年 | 7811篇 |
2005年 | 6956篇 |
2004年 | 6470篇 |
2003年 | 5694篇 |
2002年 | 5522篇 |
2001年 | 6460篇 |
2000年 | 4947篇 |
1999年 | 3822篇 |
1998年 | 3060篇 |
1997年 | 3119篇 |
1996年 | 2859篇 |
1995年 | 2741篇 |
1994年 | 2536篇 |
1993年 | 2539篇 |
1992年 | 2777篇 |
1991年 | 2732篇 |
1990年 | 2646篇 |
1989年 | 2466篇 |
1988年 | 2555篇 |
1987年 | 2535篇 |
1985年 | 3053篇 |
1984年 | 3313篇 |
1983年 | 2723篇 |
1982年 | 2918篇 |
1981年 | 2913篇 |
1980年 | 2817篇 |
1979年 | 2895篇 |
1978年 | 2993篇 |
1977年 | 3115篇 |
1976年 | 3220篇 |
1975年 | 3100篇 |
1974年 | 3083篇 |
1973年 | 3044篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
101.
Periodica Mathematica Hungarica - We present a tight parametrical Hermite–Hadamard type inequality with probability measure, which yields a considerably closer upper bound for the mean value... 相似文献
102.
Mathematical Notes - It is proved that the lattice of all Fitting classes of finite groups is not distributive, and conditions under which Fitting classes satisfy the distributive and modular laws... 相似文献
103.
Ding Q. Yao M. Wu Sh. Zeng M. Xue N. Wu D. Xu J. 《Journal of Applied Spectroscopy》2022,89(4):712-718
Journal of Applied Spectroscopy - Based on partial least squares (PLS) analysis, the effects of different smoothing points and different preprocessing methods on the accuracy and precision of the... 相似文献
104.
Stolpovskaya N. V. Kruzhilin A. A. Zorina A. V. Shikhaliev Kh. S. Ledeneva I. V. Kosheleva E. A. Vandyshev D. Yu. 《Russian Journal of Organic Chemistry》2019,55(9):1322-1328
Russian Journal of Organic Chemistry - A procedure has been proposed for the synthesis of a series of substituted N-(1,3-thiazol-2-yl)-pyrimidin-2-amines and N-(pyrimidin-2-yl)thioureas by... 相似文献
105.
Particularly-shaped silver nanostructures are successfully applied in many scientific fields, such as nanotechnology, catalysis, (nano)engineering, optoelectronics, and sensing. In recent years, the production of shape-controlled silver-based nanostructures and the knowledge around this topic has grown significantly. Hence, on the basis of the most recent results reported in the literature, a critical analysis around the driving forces behind the synthesis of such nanostructures are proposed herein, pointing out the important role of surface-regulating agents in driving crystalline growth by favoring (or opposing) development along specific directions. Additionally, growth mechanisms of the different morphologies considered here are discussed in depth, and critical points highlighted. 相似文献
106.
Back Cover: Reactions of Group 4 Metallocenes with Monosubstituted Acetonitriles: Keteniminate Formation versus CC Coupling (Chem. Eur. J. 8/2015)
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)
107.
108.
109.
Prof. Dr. Yoshio Teki 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(5):980-996
Recently, the potential use of organic π-radicals and related spin systems has been expanded to modern technological applications. The unique excited-state dynamics of organic π-radicals can be useful to improve the stability of photochemically unstable organic compounds, make the polarization transfer applicable to information technology, and achieve effective up-conversion of interest for luminescence bioimaging, among others. Furthermore, highly luminescent stable π-radicals have been recently reported, which are especially interesting for application in organic light-emitting devices owing to their potential to provide an internal quantum efficiency of 100 %. Thus, the excited-state nature of stable π-radicals as well as the control of their excited-state spin dynamics are emerging topics both in terms of fundamental science and related technological applications. In this minireview, we focus on the excited-state dynamics of both photostable non(weakly)-luminescent and luminescent π-radicals, which are opposites of each other. In particular, we cover the following topics: 1) effective generation of high-spin photoexcited states and control of the excited-state dynamics by using non-luminescent π-radicals, 2) unique excited-state dynamics of luminescent π-radicals and radical excimers, and 3) applications utilizing excited-state dynamics of π-radicals. 相似文献
110.
Two new divalent copper (C1) and zinc (C2) chelates having the formulae [M(PIMC)2] (where M = Cu(II), Zn(II) and PIMC = Ligand [(E)-3-(((3-hydroxypyridin-2-yl)imino)methyl)-4H-chromen-4-one] were obtained and characterized by several techniques. Structures and geometries of the synthesized complexes were judged based on the results of alternative analytical and spectral tools supporting the proposed formulae. IR spectral data confirmed the coordination of the ligands to the copper and zinc centers as monobasic tridentate in the enol form. Thermal analysis, UV-Vis spectra and magnetic moment confirmed the geometry around the copper center to be tetrahedral, square pyramidal and octahedral. Study of the binding ability of the synthesized compounds with Circulating tumor DNA (CT-DNA) bas been evaluated applying UV-Vis spectral titration and viscosity measurements. The copper and zinc oxides were achieved from the copper and zinc nano-particles structures Schiff base complexes as the raw material after calcination for 5 hr at 600°C. On the other hand, synthesized of C1 and C2 NPs were used as suitable precursors to the preparation of CuO and ZnO NPs. Finally, the synthesized of the two complexes exhibited enhanced activity against the tested bacterial (Staphylococcus aureus and Escherichia Coli) and fungal strains (Candida albicans and Aspergillus fumigatus) as compared to HPIMC. Among all these synthesized compounds, C1 exhibits good cleaving ability compared to other newly synthesized C2. 相似文献