全文获取类型
收费全文 | 1059篇 |
免费 | 208篇 |
国内免费 | 99篇 |
专业分类
化学 | 801篇 |
晶体学 | 13篇 |
力学 | 28篇 |
数学 | 67篇 |
物理学 | 457篇 |
出版年
2024年 | 1篇 |
2023年 | 30篇 |
2022年 | 23篇 |
2021年 | 37篇 |
2020年 | 61篇 |
2019年 | 55篇 |
2018年 | 39篇 |
2017年 | 38篇 |
2016年 | 55篇 |
2015年 | 65篇 |
2014年 | 66篇 |
2013年 | 76篇 |
2012年 | 104篇 |
2011年 | 99篇 |
2010年 | 74篇 |
2009年 | 55篇 |
2008年 | 70篇 |
2007年 | 64篇 |
2006年 | 51篇 |
2005年 | 38篇 |
2004年 | 31篇 |
2003年 | 28篇 |
2002年 | 23篇 |
2001年 | 18篇 |
2000年 | 11篇 |
1999年 | 18篇 |
1998年 | 16篇 |
1997年 | 22篇 |
1996年 | 17篇 |
1995年 | 7篇 |
1994年 | 11篇 |
1993年 | 13篇 |
1992年 | 11篇 |
1991年 | 6篇 |
1990年 | 6篇 |
1989年 | 7篇 |
1988年 | 1篇 |
1987年 | 4篇 |
1984年 | 1篇 |
1982年 | 1篇 |
1980年 | 2篇 |
1978年 | 1篇 |
1977年 | 2篇 |
1976年 | 2篇 |
1975年 | 1篇 |
1974年 | 1篇 |
1973年 | 1篇 |
1969年 | 1篇 |
1966年 | 1篇 |
1955年 | 1篇 |
排序方式: 共有1366条查询结果,搜索用时 46 毫秒
31.
32.
33.
34.
Daozhong Hu Lai Chen Jun Tian Yuefeng Su Ning Li Gang Chen Yulu Hu Yueshan Dou Shi Chen Feng Wu 《中国化学》2021,39(1):165-173
Lithium plating on graphite anode is triggered by harsh conditions of fast charge and low temperature, which significantly accelerates SOH (state of health) degradation and may cause safety issues of lithium ion batteries (LIBs). This paper has reviewed recent research progress of lithium plating on graphite anode. Firstly, we summarize the forming mechanisms of Li plating with corresponding influence factors, the detecting methods and hazard of Li plating. Then, approaches to suppress Li plating are discussed, including anode surface modification, electrolyte composition optimization and development of optimal charge strategies. Finally, we conclude and propose the remaining challenges and prospects in terms of mechanism research, detecting approaches, and suppressing methods of Li plating. This review highlights the development of Li plating research and plays a guiding rule of further study on Li plating in LIBs. 相似文献
35.
Yang Min Dr. Chuandong Dou Prof. Hongkun Tian Prof. Jun Liu Prof. Lixiang Wang 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(13):4364-4372
The B←N unit has a large dipole and it is isoelectronic to C−C moiety with no dipole. Incorporating B←N units into π-conjugated system is a powerful strategy to design organic small molecules and polymers with intriguing opto-electronic properties and excellent opto-electronic device performance. However, it is unclear how the B←N unit affects electronic structures and opto-electronic properties of large π-conjugated molecules. In this work, to address this question, we developed three dibenzo-azaacene molecules in which two B←N units were introduced at different positions. Although the dibenzo-azaacene skeleton is fully π-conjugated, the effect of B←N unit on the electronic structures of the adjacent rings is much stronger than that of the distant rings. As a result, the three molecules with isomerized B←N incorporation patterns possess different electronic structures and exhibit tunable opto-electronic properties. Among the three molecules, the centrosymmetrical molecule exhibits higher LUMO/HOMO energy levels than those of the two axisymmetrical molecules. When used as the active layer in organic field-effect transistors (OFETs), while the two axisymmetrical molecules show unipolar electron transporting property, the centrosymmetrical molecule exhibits ambipolar hole and electron transporting behavior. This work not only deepens our understanding on organoboron π-conjugated molecules, but also indicates a new strategy to tune opto-electronic properties of organic semiconductors for excellent device performance. 相似文献
36.
37.
Fei Dou Cephas Small Francoise Provencher Jason Ferreira Xuhua Wang Elham Rezasoltani Hongmei Liu Xinping Zhang 《Journal of Polymer Science.Polymer Physics》2017,55(12):940-947
We investigate the influence of particle plasmons on exciton and charge generation and recombination processes in the blend of poly (9‐(1‐octylnonyl)‐9H‐carbazole‐benzothiadiazole‐4,7‐diyl‐2,5‐thiophenediyl) (PCDTBT) and [6,6]‐phenyl‐C70butyric acid methyl ester (PC70BM). The particle plasmons are generated from gold nanoparticles, which are embedded into PCDTBT:PC70BM blend. For the blend with gold nanoparticles, we observe enhance light harvesting. Despite the enhanced light collection, we find that the quasi‐steady‐state charge generation has not been influenced by the particle plasmons. However, the generation and recombination of long‐lived (sub‐millisecond) polaron paris have been significantly enhanced: from untrapped state in the pristine blend to the trapped state in the gold nanoparticle‐embedded blend. This result implies that the plasmon‐influenced polarons are trapped at the broadband geminate polaron pair (GPP) state. This state acts as an intermediate state, which either leads to the formation of charge transfer excitons (CTXs) or free charge carriers. In our case, the particle plasmon‐influenced polarons are trapped in the GPP state, which leads to the formation of CTXs. For this reason, we do not observe the enhanced charge generation in PCDTBT:PC70BM blend with particle plasmon resonance. Finally, we revealed that the long‐lived polarons mainly resulted from the localization by particle plasmons. The macroscopic modification in the blend film made negligible contributions to this influence. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2017 , 55, 940–947 相似文献
38.
Studying the effect of oxygen in coal oxidation is very important for understanding and controlling coal spontaneous combustion. However, the oxygen effect is not very easy to determine clearly due to the large effect of heat source on coal oxidation in temperature rising experiments. Here, focused on sub-bituminous coal, the oxygen effect was separated from coal oxidation by continuously measuring FTIR spectra of coal with respect to varying temperatures and under oxygen and nitrogen. The active groups’ real-time changes of coal oxidation, thermal treatment and oxygen effect were measured. The carboxylic ester and carboxyl units are the main functional groups that increase with temperatures increasing under oxygen and nitrogen, while the other functional groups decrease in quantity. The oxygen effect promoted the consumption of aliphatic hydrocarbons and hydroxyl groups and also promoted the formation of oxygen-containing groups (except hydroxyl). Four characteristic temperature stages involved in the oxygen effect and their key functional groups were identified. Simultaneously, the relationship of oxygen consumption and chemisorption in oxygen effect was analyzed. The starting temperature of oxygen chemisorption is between 50 and 60°C. The maximum contribution of oxygen effect was observed in methyl and methylene groups. These results are important for chemical control of coal spontaneous combustion. The oxidation of aliphatic hydrocarbon should be controlled before oxygen chemisorption. The value of oxygen consumption between 70 and 80°C can be measured accurately due to the constant chemisorption rate, which help to identify the tendency for spontaneous combustion. These results will help in better understanding of the reaction mechanism of coal oxidation, especially the oxygen effect. 相似文献
39.
Chao Dou Xili Jing Shuguang Li Junjun Wu Qingbo Wang 《Optical and Quantum Electronics》2018,50(6):255
The characteristics of a novel dual-core photonic crystal fiber are investigated. In the center of photonic crystal fiber, an energy transmission channel is introduced. The optimized photonic crystal fiber can be used for polarization splitter, which has a short length and low loss. 相似文献
40.
Crystal needles of N,N′-bis(1-ethylpropyl)-3,4,9,10-perylenebis(dicarboximide) (EPPTC) are produced through p-stacking and are embedded in the thin film of poly(9,9-din-hexylfluorenyl-2,7-diyl) (PFO) when the blend solution of EPPTC and PFO in p-xylene is spin-coated onto a glass substrate. Charge transfer (CT) complex is resolved from the spectroscopic response of the blend film, which is generated only when the PFO molecules are excited. Thus, the PFO molecules are specified as donors and the H-aggregated EPPTC as acceptors in the formation of CT state (CTS). The emission resulting from the CTS in the red is further recognized by its much longer lifetime than both the intrinsic emission of the individual EPPTC molecules and that of their pure aggregates. Near-field analysis verifies that the CTS form on the boundary between the PFO and the crystal phases. The CT exciton forms by bounding the hole left on HOMO of the donor (PFO) and the indirectly transferred electron to the H-aggregate state of EPPTC, which transits back to the ground state by emitting a photon at about 650 nm. This introduces special physics in the heterojunctions that are coupled with the H-aggregates and mechanisms important for the design of organic photovoltaic devices. © 2013 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2013 相似文献