全文获取类型
收费全文 | 324714篇 |
免费 | 7145篇 |
国内免费 | 5031篇 |
专业分类
化学 | 158691篇 |
晶体学 | 4800篇 |
力学 | 18037篇 |
综合类 | 325篇 |
数学 | 48182篇 |
物理学 | 106855篇 |
出版年
2022年 | 2400篇 |
2021年 | 2980篇 |
2020年 | 3375篇 |
2019年 | 3632篇 |
2018年 | 12159篇 |
2017年 | 12672篇 |
2016年 | 9376篇 |
2015年 | 4567篇 |
2014年 | 5766篇 |
2013年 | 10785篇 |
2012年 | 13474篇 |
2011年 | 22227篇 |
2010年 | 14560篇 |
2009年 | 14632篇 |
2008年 | 19365篇 |
2007年 | 22212篇 |
2006年 | 9063篇 |
2005年 | 13836篇 |
2004年 | 10181篇 |
2003年 | 9700篇 |
2002年 | 7958篇 |
2001年 | 8030篇 |
2000年 | 6143篇 |
1999年 | 4594篇 |
1998年 | 3592篇 |
1997年 | 3445篇 |
1996年 | 3420篇 |
1995年 | 2998篇 |
1994年 | 3033篇 |
1993年 | 2766篇 |
1992年 | 3224篇 |
1991年 | 3351篇 |
1990年 | 3198篇 |
1989年 | 3077篇 |
1988年 | 2960篇 |
1987年 | 2969篇 |
1986年 | 2743篇 |
1985年 | 3255篇 |
1984年 | 3283篇 |
1983年 | 2709篇 |
1982年 | 2673篇 |
1981年 | 2444篇 |
1980年 | 2416篇 |
1979年 | 2825篇 |
1978年 | 2927篇 |
1977年 | 2776篇 |
1976年 | 2870篇 |
1975年 | 2638篇 |
1974年 | 2642篇 |
1973年 | 2697篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
51.
52.
Jie Lu Ju-Kang Wu Yao Jiang Dr. Peng Tan Lin Zhang Yu Lei Prof. Xiao-Qin Liu Prof. Lin-Bing Sun 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(16):6490-6496
Hierarchically porous metal–organic frameworks (HP-MOFs) are promising in various applications. Most reported HP-MOFs are prepared based on the generation of mesopores in microporous frameworks, and the formed mesopores are connected by microporous channels, limiting the accessibility of mesopores for bulky molecules. A hierarchical structure is formed by constructing microporous MOFs in uninterrupted mesoporous tunnels. Using the confined space in as-prepared mesoporous silica, highly dispersed metal precursors for MOFs are coated on the internal surface of mesoporous tunnels. Ligand vapor-induced crystallization is employed to enable quantitative formation of MOFs in situ, in which sublimated ligands diffuse into mesoporous tunnels and react with metal precursors. The obtained hierarchically porous composites exhibit record-high adsorption capacity for the bulky molecule trypsin. The thermal and storage stability of trypsin is improved upon immobilization on the composites. 相似文献
53.
Gurenkova Yu. S. Kornyakov I. V. Ostrovsky V. A. Skrylnikova M. A. Khramchikhin A. V. 《Russian Journal of General Chemistry》2020,90(7):1202-1206
Russian Journal of General Chemistry - 8-Phenyltetrazolo[5,1-b][1,3,4]thiadiazepine was obtained as a result of intermolecular cyclization of 1-amino-1H-tetrazole-5-thiol and 3-phenyl-2-propynal.... 相似文献
54.
V. A. Bespalov V. M. Glazov E. A. Il’ichev Yu. A. Klimov S. V. Kuklev A. E. Kuleshov R. M. Nabiev G. N. Petrukhin B. G. Potapov G. S. Rychkov D. S. Sokolov V. V. Fandeev E. A. Fetisov S. S. Yakushov 《Technical Physics》2015,60(4):553-560
The results of investigation of optical image detectors designed for the largest problem, near-VUV, range of the spectrum are presented. The possibility of using a dual-stage image detection system to appreciably lower the sensitivity threshold and make computer data processing feasible is considered. The integration of a UV module into a wideband image detector is studied. 相似文献
55.
56.
57.
58.
A. Lashgari S. Ghammamy R. Ramirez-Tagle G. Salgado-Moran 《Journal of Structural Chemistry》2015,56(8):1505-1513
Two new compounds of fluorine: (C2H5)4N[I2F] and (C2H5)4N[Br2F], have been easily synthesized in a nearly quantitative by a direct reaction of (C2H5)4NF, I2 and Br2. The products were isolated and characterized by elemental analysis and spectroscopic methods such as: Fourier transform infrared spectroscopy (FTIR) and ultraviolet-visible spectroscopy (UV-Vis). These compounds have been studied computationally with the Scalar ZORA relativistic level of theory using the ADF program package. The molecular parameters, and vibrational spectra were calculated. The excitation energies were found by timedependent perturbation density functional theory (TD-DFT). Molecule optimization, frequencies and excitation energies were calculated with standard Slatertype-orbital (STO) basis sets with triple-zeta quality double plus polarization functions (TZ2P) for all atoms. The FTIR, UV-Vis spectra and assignment of principal transitions and total density of state (TDOS) were extracted using the GaussSum 2.2 program. The comparison between experimental and calculated values showes that the experimental results correlate well with the predicted data. 相似文献
59.
Applied Magnetic Resonance - The suggested approach allowed us to derive analytical expressions for modeling the shape of solid-echo signal and its time evolution for a system of three-spin groups... 相似文献
60.