全文获取类型
收费全文 | 1585483篇 |
免费 | 41171篇 |
国内免费 | 15444篇 |
专业分类
化学 | 694317篇 |
晶体学 | 20748篇 |
力学 | 77273篇 |
综合类 | 434篇 |
数学 | 245937篇 |
物理学 | 387702篇 |
无线电 | 215687篇 |
出版年
2021年 | 17263篇 |
2020年 | 19603篇 |
2019年 | 19792篇 |
2018年 | 15386篇 |
2017年 | 13466篇 |
2016年 | 32199篇 |
2015年 | 24637篇 |
2014年 | 36213篇 |
2013年 | 82835篇 |
2012年 | 45278篇 |
2011年 | 42081篇 |
2010年 | 43429篇 |
2009年 | 48229篇 |
2008年 | 43952篇 |
2007年 | 40356篇 |
2006年 | 46970篇 |
2005年 | 38474篇 |
2004年 | 39304篇 |
2003年 | 36833篇 |
2002年 | 37600篇 |
2001年 | 37307篇 |
2000年 | 32987篇 |
1999年 | 30479篇 |
1998年 | 28594篇 |
1997年 | 28385篇 |
1996年 | 27841篇 |
1995年 | 25467篇 |
1994年 | 24823篇 |
1993年 | 24058篇 |
1992年 | 23866篇 |
1991年 | 24045篇 |
1990年 | 22752篇 |
1989年 | 22232篇 |
1988年 | 21360篇 |
1987年 | 20103篇 |
1986年 | 18904篇 |
1985年 | 25352篇 |
1984年 | 26464篇 |
1983年 | 22366篇 |
1982年 | 23725篇 |
1981年 | 22882篇 |
1980年 | 22123篇 |
1979年 | 22097篇 |
1978年 | 23296篇 |
1977年 | 22899篇 |
1976年 | 22474篇 |
1975年 | 21159篇 |
1974年 | 20769篇 |
1973年 | 21246篇 |
1972年 | 15464篇 |
排序方式: 共有10000条查询结果,搜索用时 484 毫秒
11.
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
12.
Automotive proton exchange membrane fuel cell stacks need to meet manufacturer specified rated beginning-of-life (BOL) performance before being assembled into vehicles and shipped off to customers. The process of “breaking-in” of a freshly assembled stack is often referred to as “conditioning.” It has become an intensely researched area especially in automotive companies, where imminent commercialization of fuel cell electric vehicles (FCEVs) demands a short, energy- and cost-efficient, and practical conditioning protocol. Significant advances in reducing the conditioning time from 1 to 2 days to as low as 4h or less, in some cases without the use of additional inert gases such as nitrogen, and with minimal use of hydrogen, and specialized test stations will be discussed. 相似文献
13.
Semiconductors - In this work, we discuss for the first time the principle of rotation in the constant electric field of a conducting particle with participation of the Lorentz force, which ensures... 相似文献
14.
Zienko S. I. Zhbanova V. L. 《Journal of Communications Technology and Electronics》2022,67(4):395-402
Journal of Communications Technology and Electronics - A quantitative comparison of the spectral characteristics of the human visual system and matrix photodetectors is carried out. Criteria for a... 相似文献
15.
Wireless Personal Communications - Chronic kidney disease (CKD) is a gradual loss of kidney function over the period of time and it is irrevocable once functionality reaches the critical state.... 相似文献
16.
Xiao Zhu Chen Yanxun Jiang Hongbo Hu Zhenzhen Lui John C. S. Min Geyong Dustdar Schahram 《Wireless Networks》2022,28(7):3305-3322
Wireless Networks - Unmanned aerial vehicles (UAV) have been widely used in various fields because of their high mobility and portability. At the same time, due to the rapid development of... 相似文献
17.
JETP Letters - A new approach to search for axions in the storage ring experiments, applicable at a short coherence time of the in-plane polarization as is the case for protons is discussed. The... 相似文献
18.
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
19.
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
20.
Gaineev A. M. Galkina I. V. Davletshin R. R. Davletshina N. V. Kuznetsov N. O. Grishaev D. Yu. Shulayeva M. P. Pozdeev O. K. 《Russian Journal of General Chemistry》2022,92(7):1208-1213
Russian Journal of General Chemistry - Aminophosphabetaines, i.e., isobutyl {[alkyl(dimethyl)ammonio]methyl}phosphonates with higher alkyl substituents at the nitrogen atom, were obtained by a... 相似文献