全文获取类型
收费全文 | 252810篇 |
免费 | 3904篇 |
国内免费 | 1892篇 |
专业分类
化学 | 117072篇 |
晶体学 | 3999篇 |
力学 | 13620篇 |
综合类 | 112篇 |
数学 | 39514篇 |
物理学 | 84289篇 |
出版年
2020年 | 1198篇 |
2019年 | 1194篇 |
2018年 | 10618篇 |
2017年 | 11485篇 |
2016年 | 6407篇 |
2015年 | 2679篇 |
2014年 | 2399篇 |
2013年 | 6292篇 |
2012年 | 9603篇 |
2011年 | 19297篇 |
2010年 | 11766篇 |
2009年 | 11595篇 |
2008年 | 16506篇 |
2007年 | 20243篇 |
2006年 | 5573篇 |
2005年 | 12472篇 |
2004年 | 8029篇 |
2003年 | 7445篇 |
2002年 | 5228篇 |
2001年 | 4679篇 |
2000年 | 3682篇 |
1999年 | 2852篇 |
1998年 | 2364篇 |
1997年 | 2359篇 |
1996年 | 2374篇 |
1995年 | 2228篇 |
1994年 | 1947篇 |
1993年 | 1854篇 |
1992年 | 2051篇 |
1991年 | 2021篇 |
1990年 | 1948篇 |
1989年 | 1929篇 |
1988年 | 1912篇 |
1987年 | 1866篇 |
1986年 | 1772篇 |
1985年 | 2329篇 |
1984年 | 2429篇 |
1983年 | 2023篇 |
1982年 | 2330篇 |
1981年 | 2139篇 |
1980年 | 2180篇 |
1979年 | 2179篇 |
1978年 | 2314篇 |
1977年 | 2141篇 |
1976年 | 2206篇 |
1975年 | 2131篇 |
1974年 | 1964篇 |
1973年 | 2209篇 |
1972年 | 1339篇 |
1968年 | 1156篇 |
排序方式: 共有10000条查询结果,搜索用时 12 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.
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
3.
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
4.
High Energy Chemistry - Modification of Polyvinylidene fluoride (PVDF) by radiation grafting is a research hotspot in recent years. In this study, the monomer 2-Hydroxyethyl methacrylate (HEMA) was... 相似文献
5.
Theoretical and Mathematical Physics - Dynamic systems acting on the plane and possessing the Wada property have been observed. There exist only two topological types, symmetric and antisymmetric,... 相似文献
6.
7.
Li Y. Shi W. H. Dong L. M. Xu S. X. Huang H. J. Yin J. R. 《Journal of Applied Spectroscopy》2022,89(3):534-541
Journal of Applied Spectroscopy - Sr3B2O6:Dy3+, Eu3+ single-matrix white-light-emitting materials are prepared using the high-temperature solid-state method. The microstructure, emission spectrum,... 相似文献
8.
Journal of Algebraic Combinatorics - A dessin is called circular if the boundary of each face is a circuit (a simple cycle). In this paper, we address the problem of characterizing edge-transitive... 相似文献
9.
Ajit Kumar Singh Seulgi Ji Baghendra Singh Chittaranjan Das Heechae Choi Prashanth W. Menezes Arindam Indra 《Materials Today Chemistry》2022
Herein, we report a Mott-Schottky catalyst by entrapping cobalt nanoparticles inside the N-doped graphene shell (Co@NC). The Co@NC delivered excellent oxygen evolution activity with an overpotential of merely 248 mV at a current density of 10 mA cm–2 with promising long-term stability. The importance of Co encapsulated in NC has further been demonstrated by synthesizing Co nanoparticles without NC shell. The synergy between the hexagonal close-packed (hcp) and face-centered cubic (fcc) Co plays a major role to improve the OER activity, whereas the NC shell optimizes the electronic structure, improves the electron conductivity, and offers a large number of active sites in Co@NC. The density functional theory calculations have revealed that the hcp Co has a dominant role in the surface reaction of electrocatalytic oxygen evolution, whereas the fcc phase induces the built-in electric field at the interfaces with N-doped graphene to accelerate the H+ ion transport. 相似文献
10.
Restricted testing conditions were considered recently. For the maximal operator, Hytönen, Li and Sawyer [8] first obtained parental testing condition. Later, they [9] showed that it suffices to restrict testing to doubling cubes. Chen and Lacey [3] gave a similar restricted testing condition. In our paper, we discuss a version of the latter in the multilinear setting.
相似文献