全文获取类型
收费全文 | 34186篇 |
免费 | 5470篇 |
国内免费 | 5035篇 |
专业分类
化学 | 25650篇 |
晶体学 | 439篇 |
力学 | 1917篇 |
综合类 | 465篇 |
数学 | 4088篇 |
物理学 | 12132篇 |
出版年
2024年 | 87篇 |
2023年 | 549篇 |
2022年 | 1009篇 |
2021年 | 1113篇 |
2020年 | 1283篇 |
2019年 | 1422篇 |
2018年 | 1129篇 |
2017年 | 1046篇 |
2016年 | 1690篇 |
2015年 | 1775篇 |
2014年 | 2085篇 |
2013年 | 2586篇 |
2012年 | 2877篇 |
2011年 | 2966篇 |
2010年 | 2285篇 |
2009年 | 2201篇 |
2008年 | 2523篇 |
2007年 | 2236篇 |
2006年 | 2052篇 |
2005年 | 1864篇 |
2004年 | 1509篇 |
2003年 | 1328篇 |
2002年 | 1525篇 |
2001年 | 1222篇 |
2000年 | 900篇 |
1999年 | 699篇 |
1998年 | 455篇 |
1997年 | 359篇 |
1996年 | 313篇 |
1995年 | 254篇 |
1994年 | 193篇 |
1993年 | 178篇 |
1992年 | 183篇 |
1991年 | 171篇 |
1990年 | 132篇 |
1989年 | 96篇 |
1988年 | 85篇 |
1987年 | 54篇 |
1986年 | 56篇 |
1985年 | 52篇 |
1984年 | 33篇 |
1983年 | 19篇 |
1982年 | 11篇 |
1981年 | 6篇 |
1980年 | 11篇 |
1979年 | 11篇 |
1978年 | 15篇 |
1977年 | 5篇 |
1974年 | 6篇 |
1936年 | 4篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
Energy storage is an important adjustment method to improve the economy and reliability of a power system. Due to the complexity of the coupling relationship of elements such as the power source, load, and energy storage in the microgrid, there are problems of insufficient performance in terms of economic operation and efficient dispatching. In view of this, this paper proposes an energy storage configuration optimization model based on reinforcement learning and battery state of health assessment. Firstly, a quantitative assessment of battery health life loss based on deep learning was performed. Secondly, on the basis of considering comprehensive energy complementarity, a two-layer optimal configuration model was designed to optimize the capacity configuration and dispatch operation. Finally, the feasibility of the proposed method in microgrid energy storage planning and operation was verified by experimentation. By integrating reinforcement learning and traditional optimization methods, the proposed method did not rely on the accurate prediction of the power supply and load and can make decisions based only on the real-time information of the microgrid. In this paper, the advantages and disadvantages of the proposed method and existing methods were analyzed, and the results show that the proposed method can effectively improve the performance of dynamic planning for energy storage in microgrids. 相似文献
82.
Two copper(Ⅱ)coordination polymers{[Cu(bib)(nip)]·1.5H2O}n(1)and[Cu2(bib)(glu)2]n(2)(bib= 1,4-bis(2-methyl-imidazol-1-yl)butane,H2nip = 5-nitroisophthalic acid,... 相似文献
83.
Zelong Gong Xuefeng Gao Qingqing Yang Jingxian Lun Hansen Xiao Jiayu Zhong Hong Cao 《Molecules (Basel, Switzerland)》2022,27(13)
Enterovirus 71 (EV71) is a dominant pathogenic agent that may cause severe central nervous system (CNS) diseases among infants and young children in the Asia-pacific. The inflammasome is closely implicated in EV71-induced CNS injuries through a series of signaling pathways. However, the activation pathway of NLRP3 inflammasome involved in EV71-mediated CNS injuries remains poorly defined. In the studies, EV71 infection, ERK1/2 phosphorylation, and activation of NLRP3 are abolished in glioblastoma cells with low vimentin expression by CRISPR/Cas9-mediated knockdown. PD098059, an inhibitor of p-ERK, remarkably blocks the vimentin-mediated ERK1/2 phosphorylation in EV71-infected cells. Nuclear translocation of NF-κB p65 is dependent on p-ERK in a time-dependent manner. Moreover, NLRP3 activation and caspase-1 production are limited in EV71-infected cells upon the caffeic acid phenethyl ester (CAPE) administration, an inhibitor of NF-κB, which contributes to the inflammasome regulation. In conclusion, these results suggest that EV71-mediated NLRP3 inflammasome could be activated via the VIM-ERK-NF-κB pathway, and the treatment of the dephosphorylation of ERK and NF-κB inhibitors is beneficial to host defense in EV71-infected CNS. 相似文献
84.
85.
86.
Yuxin Xiao Hailan Wang Zongliang Xie Mingyao Shen Rongjuan Huang Yuchen Miao Guanyu Liu Tao Yu Wei Huang 《Chemical science》2022,13(31):8906
Near-infrared (NIR) light-emitting materials show excellent potential applications in the fields of military technology, bioimaging, optical communication, organic light-emitting diodes (OLEDs), etc. Recently, thermally activated delayed fluorescence (TADF) emitters have made historic developments in the field of OLEDs. These metal-free materials are more attractive because of efficient reverse intersystem crossing processes which result in promising high efficiencies in OLEDs. However, the development of NIR TADF emitters has progressed at a relatively slower pace which could be ascribed to the difficult promotion of external quantum efficiencies. Thus, increasing attention has been paid to NIR TADF emitters. In this review, the recent progress of NIR TADF emitters has been summarized along with their molecular design strategies and photophysical properties, as well as electroluminescence performance data of their OLEDs, respectively.This review presents the recent progress of NIR TADF emitters along with their molecular design strategies and photophysical properties, as well as the electroluminescence performance data of the emitters and their OLEDs. 相似文献
87.
分析比较了低温等离子体模拟中采用的流体模型、粒子模型和混合模拟方法及在放电特性分析中采用的电路模拟方法。给出了每种方法的基本原理,探讨了它们的适应性。利用粒子模型对外磁镜场作用下四阳极装置辉光放电所产生等离子体进行了模拟,分析了磁场对电子密度径向分布的影响。 相似文献
88.
In Phys. Lett. A 313 (2003) 343 we have found that the
self-reciprocal Hankel transformation (HT) is embodied in quantum
mechanics by a transform between two entangled state representations
of continuum variables. In this
work we study Hankel transforms and properties of Bessel function via
entangled state representations' transformation in quantum mechanics. 相似文献
89.
Luhua Xiao Xiaoying Lu Huilin Yang Cuiqing Lin Le Li Chen Ni Yuan Fang Suifen Mo Ruoting Zhan Ping Yan 《Molecules (Basel, Switzerland)》2022,27(11)
In this study, the antioxidant and hypolipidemic effects of Mesona Chinensis Benth (MCB) extracts were evaluated. Seven fractions (F0, F10, F20, F30, F40, F50 and MTF) were obtained from the MCB ethanol extracts. Compared to the commercial antioxidants (vitamin C), MTF and F30 exhibited higher antioxidant activities in the antiradical activity test and the FRAP assay. The half-inhibition concentration (IC50) for MTF and F30 were 5.323 µg/mL and 5.278 µg/mL, respectively. MTF at 200 µg/mL significantly decreased the accumulation of TG in oleic acid (OA)-induced HepG2 cells and reversed the inhibitory effect of Compound C on AMPK (MTF and F30 significantly increased the glucose utilization of insulin-induced HepG2 cells). In addition, the components of MTF were identified by HPLC-MS, which were caffeic acid, quercetin 3-O-galactoside, isoquercetin, astragalin, rosmarinic acid, aromadendrin-3-O-rutinoside, rosmarinic acid-3-O-glucoside and kaempferol-7-O-glucoside. Through statistical correlations by Simca P software, it was found that the main antioxidant and hypolipidemic components of MCB might be caffeic acid, kaempferol-7-O-glucoside, rosmarinic acid-3-O-glucoside and aromadendrin-3-O-rutinoside, which may play important roles in the AMPK pathway. MTF and F30 in MCB could be potential health products for the treatment of hyperlipidemia. 相似文献
90.