全文获取类型
收费全文 | 303424篇 |
免费 | 14414篇 |
国内免费 | 7793篇 |
专业分类
化学 | 164435篇 |
晶体学 | 4152篇 |
力学 | 16995篇 |
综合类 | 325篇 |
数学 | 33440篇 |
物理学 | 106284篇 |
出版年
2022年 | 4240篇 |
2021年 | 4871篇 |
2020年 | 5309篇 |
2019年 | 5536篇 |
2018年 | 6411篇 |
2017年 | 6255篇 |
2016年 | 8459篇 |
2015年 | 5876篇 |
2014年 | 8549篇 |
2013年 | 14566篇 |
2012年 | 14169篇 |
2011年 | 15777篇 |
2010年 | 11742篇 |
2009年 | 11708篇 |
2008年 | 13200篇 |
2007年 | 12578篇 |
2006年 | 11383篇 |
2005年 | 9850篇 |
2004年 | 8886篇 |
2003年 | 7770篇 |
2002年 | 7676篇 |
2001年 | 9019篇 |
2000年 | 6919篇 |
1999年 | 5686篇 |
1998年 | 4832篇 |
1997年 | 4669篇 |
1996年 | 4319篇 |
1995年 | 3792篇 |
1994年 | 3563篇 |
1993年 | 3354篇 |
1992年 | 3595篇 |
1991年 | 3816篇 |
1990年 | 3574篇 |
1989年 | 3441篇 |
1988年 | 3258篇 |
1987年 | 3278篇 |
1986年 | 2970篇 |
1985年 | 3662篇 |
1984年 | 3565篇 |
1983年 | 2940篇 |
1982年 | 2971篇 |
1981年 | 2835篇 |
1980年 | 2598篇 |
1979年 | 3000篇 |
1978年 | 3174篇 |
1977年 | 3283篇 |
1976年 | 3292篇 |
1975年 | 3012篇 |
1974年 | 2975篇 |
1973年 | 3077篇 |
排序方式: 共有10000条查询结果,搜索用时 16 毫秒
1.
Liu Wenbin Huang Yiwei Huang Guolin Fan Lijiao Xie Yuming Shi Jeffery 《Journal of Radioanalytical and Nuclear Chemistry》2022,331(5):2055-2068
Journal of Radioanalytical and Nuclear Chemistry - Eco-friendly and low-cost composite, amidoxime-functionalized microcrystalline cellulose/mesoporous silica (MCC/MS-AO), were synthesized by... 相似文献
2.
3.
Kinetics and Catalysis - The catalytic properties of a nickel phosphide catalyst supported on silica gel in the reductive amination of carbonyl compounds were studied in a flow reactor using... 相似文献
4.
Zhihong Zhao Bin Wang Rui Tan Wenjing Liu Minghui Zhang 《Magnetic resonance in chemistry : MRC》2022,60(4):427-433
In this study, the transverse relaxation time (T2) of activated carbon (AC) in different relative environment humidity was detected firstly by low-field nuclear magnetic resonance (LFNMR). The pore size (diameter) of AC distributions was calculated by the relationship between T2 and surface relaxation rate (ρ), where ρ was obtained by the detection of nine porous materials with known pore size. The results showed that the pore size distributions of AC calculated by ρ < 0.19 nm/ms were in good agreement with that obtained by nitrogen adsorption method and proved that LFNMR as a new detection method was feasible for characterizing AC pore size distribution. 相似文献
5.
Yang T. L. Kao C. L. Kuo C. E. Yeh H. C. Li W. J. Li H. T. Chen C. Y. 《Chemistry of Natural Compounds》2022,58(5):825-827
Chemistry of Natural Compounds - A novel bibenzyl derivative, hydrangchinenin (1), was isolated from the stems of Hydrangea chinensis Maxim. (Hydrangeaceae). Its structure was determined on the... 相似文献
6.
7.
Zhang Bing Yang Jie-qin Liu Ying Hu Bin Yang Yang Zhao Li Lu Qiang 《Cellulose (London, England)》2022,29(12):6565-6578
Cellulose - Heating is essential in various biomass pre-treatments and thermal conversion processes. It is of practical significance to study the characteristics of cellulose-lignin and... 相似文献
8.
Nonlinear Dynamics - In this paper, a (2+1)-dimensional Caudrey–Dodd–Gibbon–Kotera–Sawada system is investigated in fluid mechanics via the symbolic computation. With the... 相似文献
9.
Mathematical Programming - We provide a control-theoretic perspective on optimal tensor algorithms for minimizing a convex function in a finite-dimensional Euclidean space. Given a function... 相似文献
10.
Qianqian Fan Zirui Liu Feng Qiu Prof. Yong Mao Prof. Qingju Liu Prof. Longzhou Zhang 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(63):e202202700
The artificially accurate design of nonmetal electrocatalysts’ active site has been a huge challenge because no pure active species with the specific structure could be strictly controlled by traditional synthetic methods. Species with a multiconfiguration in the catalyst hinder identification of the active site and the subsequent comprehension of the reaction mechanism. We have developed a novel electro-assisted molecular assembly strategy to obtain a pure pentagon ring on perfect graphene avoiding other reconstructed structures. More importantly, the active atom was confirmed by the subtle passivation process as the topmost carbon atom. Recognition of the carbon-defect electrocatalysis reaction mechanism was first downsized to the single-atom scale from the experimental perspective. It is expected that this innovative electro-assisted molecular assembly strategy could be extensively applied in the active structure-controlled synthesis of nonmetal electrocatalysts and verification of the exact active atom. 相似文献