全文获取类型
收费全文 | 96159篇 |
免费 | 1468篇 |
国内免费 | 1997篇 |
专业分类
化学 | 38422篇 |
晶体学 | 946篇 |
力学 | 7103篇 |
综合类 | 11篇 |
数学 | 34404篇 |
物理学 | 18738篇 |
出版年
2023年 | 162篇 |
2022年 | 137篇 |
2021年 | 424篇 |
2020年 | 421篇 |
2019年 | 444篇 |
2018年 | 10707篇 |
2017年 | 10556篇 |
2016年 | 6747篇 |
2015年 | 1484篇 |
2014年 | 1046篇 |
2013年 | 1937篇 |
2012年 | 5309篇 |
2011年 | 12045篇 |
2010年 | 6554篇 |
2009年 | 7161篇 |
2008年 | 7666篇 |
2007年 | 9790篇 |
2006年 | 1157篇 |
2005年 | 2230篇 |
2004年 | 2712篇 |
2003年 | 2808篇 |
2002年 | 1777篇 |
2001年 | 612篇 |
2000年 | 567篇 |
1999年 | 363篇 |
1998年 | 398篇 |
1997年 | 328篇 |
1996年 | 380篇 |
1995年 | 275篇 |
1994年 | 195篇 |
1993年 | 241篇 |
1992年 | 173篇 |
1991年 | 143篇 |
1990年 | 135篇 |
1989年 | 134篇 |
1988年 | 130篇 |
1987年 | 117篇 |
1986年 | 125篇 |
1985年 | 144篇 |
1984年 | 145篇 |
1983年 | 107篇 |
1982年 | 110篇 |
1981年 | 101篇 |
1980年 | 108篇 |
1979年 | 81篇 |
1978年 | 71篇 |
1977年 | 59篇 |
1976年 | 45篇 |
1975年 | 43篇 |
1914年 | 45篇 |
排序方式: 共有10000条查询结果,搜索用时 62 毫秒
1.
Dariusz Marek Adam Domaski Joanna Domaska Jakub Szygua Tadeusz Czachrski Jerzy Klamka 《Entropy (Basel, Switzerland)》2021,23(5)
In this article, a way to employ the diffusion approximation to model interplay between TCP and UDP flows is presented. In order to control traffic congestion, an environment of IP routers applying AQM (Active Queue Management) algorithms has been introduced. Furthermore, the impact of the fractional controller and its parameters on the transport protocols is investigated. The controller has been elaborated in accordance with the control theory. The TCP and UDP flows are transmitted simultaneously and are mutually independent. Only the TCP is controlled by the AQM algorithm. Our diffusion model allows a single TCP or UDP flow to start or end at any time, which distinguishes it from those previously described in the literature. 相似文献
2.
Nonlinear Dynamics - The classical Kuramoto model serves as a useful tool for studying synchronization transitions in coupled oscillators that is limited to the sinusoidal and pairwise... 相似文献
3.
Archiv der Mathematik - In this note, we introduce a criterion to detect vanishing of essential algebras of a Green biset functor by means of morphisms. We introduce the inflation morphism and... 相似文献
4.
Xinghuo Xiao Wenyan Wang Jiali Wang Prof. Can Yang Prof. Guigang Zhang Prof. Xianjun Lang 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(52):e202201244
Conjugated polymers feature promising structure and properties for photocatalytic water splitting. Herein, a hydrolysis strategy was demonstrated to rationally modulate the surface hydrophilicity and band structures of conjugated poly-benzothiadiazoles. High hydrophilicity not only enhances the dispersions of polymeric solids in an aqueous solution but also reduces the absorption energy of water molecules. Besides, both theoretical and experimental results reveal that a more positive valence band potential is generated, which contributes to enhancing the photocatalytic water oxidation performance. Accordingly, the surface-modified conjugated polymers show largely promoted photocatalytic water oxidation activities by deposition of cobalt oxides as cocatalysts. 相似文献
5.
Zhongxian Fan Jiaen Xie Dr. Tumpa Sadhukhan Chao Liang Can Huang Wenqing Li Tingxuan Li Dr. Pingyu Zhang Dr. Samya Banerjee Dr. Krishnan Raghavachari Dr. Huaiyi Huang 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(3):e202103346
Four photo-catalysts of the general formula [Ir(CO6/ppy)2(L)]Cl where CO6=coumarin 6 ( Ir1 – Ir3 ), ppy=2-phenylpyridine ( Ir4 ), L=4′-(3,5-di-tert-butylphenyl)-2,2′ : 6′,2′′-terpyridine ( Ir1 ), 4′-(3,5-bis(trifluoromethyl)phenyl)-2,2′ : 6′,2′′-terpyridine ( Ir2 and Ir4 ), and 4-([2,2′ : 6′,2′′-terpyridin]-4′-yl)-N,N-dimethylaniline ( Ir3 ) were synthesized and characterized. These photostable photo-catalysts ( Ir1 – Ir3 ) showed strong visible light absorption between 400–550 nm. Upon light irradiation (465 and 525 nm), Ir1 – Ir3 generated singlet oxygen and induced rapidly photo-catalytic oxidation of cellular coenzymes NAD(P)H. Ir1 – Ir3 showed time-dependent cellular uptake with excellent intracellular retention efficiency. Upon green light irradiation (525 nm), Ir2 provided a much higher photo-index (PI=793) than the clinically used photosensitizer, 5-aminolevulinicacid (5-ALA, PI>30) against HeLa cancer cells. The observed necro-apoptotic anticancer activity of Ir2 was due to the Ir2 triggered photo-induced intracellular redox imbalance (by NAD(P)H oxidation and ROS generation) and change in the mitochondrial membrane potential. Remarkably, Ir2 showed in vivo photo-induced catalytic anticancer activity in mouse models. 相似文献
6.
Zayed Elsayed M. E. Shohib Reham M. A. Alngar Mohamed E. M. Yıldırım Yakup 《Computational Mathematics and Modeling》2021,32(2):235-252
Computational Mathematics and Modeling - Based on the extended simplest equation method, we construct solitons and other solutions for the nonlinear convection-diffusion-reaction equation with... 相似文献
7.
Karakuş Erman Erdemir Eda Suna Garen Liv Lokman Gunduz Simay Can Şevval Arzu 《Journal of fluorescence》2021,31(6):1617-1625
Journal of Fluorescence - We have constructed a novel fluorescein-based fluorescent chemosensor, FL-In, functionalised with an indole moiety and capable of sensing by both the optical... 相似文献
8.
Aequationes mathematicae - In this paper, we establish a new class of dynamic inequalities of Hardy’s type which generalize and improve some recent results given in the literature. More... 相似文献
9.
Hu Bing Guo Fangsong Li Shanrong Yang Can Lin Wei Zhang Jinshui Hou Yidong Wang Xinchen 《Research on Chemical Intermediates》2022,48(6):2295-2311
Research on Chemical Intermediates - Element doping has demonstrated an effective strategy for enhancing photocatalytic performance of carbon nitride (CN). Herein, we reported that oxygen-doped CN... 相似文献
10.
Dr. Joaquim Torra Dr. Felipe Viela Dr. Diego Megías Dr. Begoña Sot Prof. Cristina Flors 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(19):e202200026
CRANAD-2 is a fluorogenic curcumin derivative used for near-infrared detection and imaging in vivo of amyloid aggregates, which are involved in neurodegenerative diseases. We explore the performance of CRANAD-2 in two super-resolution imaging techniques, namely stimulated emission depletion (STED) and single-molecule localization microscopy (SMLM), with markedly different fluorophore requirements. By conveniently adapting the concentration of CRANAD-2, which transiently binds to amyloid fibrils, we show that it performs well in both techniques, achieving a resolution in the range of 45–55 nm. Correlation of SMLM with atomic force microscopy (AFM) validates the resolution of fine features in the reconstructed super-resolved image. The good performance and versatility of CRANAD-2 provides a powerful tool for near-infrared nanoscopic imaging of amyloids in vitro and in vivo. 相似文献