全文获取类型
收费全文 | 11599篇 |
免费 | 509篇 |
国内免费 | 156篇 |
专业分类
化学 | 8298篇 |
晶体学 | 109篇 |
力学 | 561篇 |
综合类 | 3篇 |
数学 | 1359篇 |
物理学 | 1934篇 |
出版年
2024年 | 29篇 |
2023年 | 100篇 |
2022年 | 528篇 |
2021年 | 486篇 |
2020年 | 425篇 |
2019年 | 484篇 |
2018年 | 506篇 |
2017年 | 416篇 |
2016年 | 685篇 |
2015年 | 475篇 |
2014年 | 644篇 |
2013年 | 1202篇 |
2012年 | 896篇 |
2011年 | 855篇 |
2010年 | 625篇 |
2009年 | 495篇 |
2008年 | 551篇 |
2007年 | 489篇 |
2006年 | 343篇 |
2005年 | 344篇 |
2004年 | 210篇 |
2003年 | 214篇 |
2002年 | 178篇 |
2001年 | 94篇 |
2000年 | 63篇 |
1999年 | 72篇 |
1998年 | 45篇 |
1997年 | 53篇 |
1996年 | 53篇 |
1995年 | 37篇 |
1994年 | 41篇 |
1993年 | 24篇 |
1992年 | 41篇 |
1991年 | 38篇 |
1990年 | 30篇 |
1989年 | 40篇 |
1988年 | 35篇 |
1987年 | 37篇 |
1986年 | 32篇 |
1985年 | 37篇 |
1984年 | 38篇 |
1983年 | 21篇 |
1982年 | 31篇 |
1981年 | 21篇 |
1980年 | 27篇 |
1979年 | 22篇 |
1978年 | 18篇 |
1977年 | 15篇 |
1976年 | 15篇 |
1974年 | 16篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
Santa Islam Syed Shaheen Shah Prof. Shamsun Naher Dr. Muhammad Ali Ehsan Dr. Md. Abdul Aziz Dr. A. J. Saleh Ahammad 《化学:亚洲杂志》2021,16(22):3516-3543
Dopamine (DA) is an important neurotransmitter, which is created and released from the central nervous system. It plays a crucial role in human activities, like cognition, emotions, and response to anything. Maladjustment of DA in human blood serum results in different neural diseases, like Parkinson's and Schizophrenia. Consequently, researchers have started working on DA detection in blood serum, which is undoubtedly a hot research area. Electrochemical sensing techniques are more promising to detect DA in real samples. However, utilizing conventional electrodes for selective determination of DA encounters numerous problems due to the coexistence of other materials, such as uric acid and ascorbic acid, which have an oxidation potential close to DA. To overcome such problems, researchers have put their focus on the modification of bare electrodes. The aim of this review is to present recent advances in modifications of most used bare electrodes with carbonaceous materials, especially graphene, its derivatives, and carbon nanotubes, for electrochemical detection of DA. A brief discussion about the mechanistic phenomena at the electrode interface has also been included in this review. 相似文献
992.
Patrick W. Fritz Prof. Ali Coskun 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(27):7489-7501
With the advent of silicon-based semiconductors, a plethora of previously unknown technologies became possible. The development of lightweight low-dimensional organic semiconductors followed soon after. However, the efficient charge/electron transfers enabled by the non-porous 3D structure of silicon is rather challenging to be realized by their (metal-)organic counterparts. Nevertheless, the demand for lighter, more efficient semiconductors is steadily increasing resulting in a growing interest in (metal-)organic semiconductors. These novel materials are faced with a variety of challenges originating from their chemical design, their packing and crystallinity. Although the effect of molecular design is quite well understood, the influence of dimensionality and the associated change in properties (porosity, packing, conjugation) is still an uncharted area in (metal-)organic semiconductors, yet highly important for their practical utilization. In this Minireview, an overview on the design and synthesis of porous semiconductors, with a particular emphasis on organic semiconductors, is presented and the influence of dimensionality is discussed. 相似文献
993.
Design of donor–acceptor–donor (D–A–D) type small molecule donor materials with efficient photovoltaic parameters 下载免费PDF全文
Muhammad Irfan Javed Iqbal Sana Sadaf Bertil Eliasson Usman Ali Rana Salah Ud‐din Khan Khurshid Ayub 《International journal of quantum chemistry》2017,117(10)
Four Donor–Acceptor–Donor (D–A–D) type of donor molecules (M1‐M4) with triphenylamine (TPA) as donor moiety, thiophene as bridge, and thiazolothiazole as acceptor unit were designed and its photovoltaic parameters were equated with reference molecule “R.” DFT functional CAM‐B3LYP/6‐31G (d,p) was found best for geometry optimization and TD‐CAM‐B3LYP/6‐31G (d,p) was found suitable for excited state calculations. Among designed donor molecules, M4 manifests suitable lowest band gap of 4.73 eV, frontier molecular orbital energy levels as well as distinctive broad absorption of 455.3 nm due to the stronger electron withdrawing group. The electron‐withdrawing substituents contribute to red shifts of absorption spectra and better stabilities for designed molecules. The theoretically determined reorganization energies of designed donor molecules suggested excellent charge mobility property. The lower λe values in comparison with λh illustrated that these four donor materials would be ideal for electron transfer and M4 would be best amongst the investigated molecules with lowest λe of 0.0177. Furthermore, the calculated Voc of M4 is 2.04 V with respect to PC60BM (phenyl‐C61‐butyric acid methyl ester). This study revealed that the designed donor materials are suitable and recommended for high performance organic solar cell devices. 相似文献
994.
Ali Saad Manef Abderrabba Mohamed M. Chehimi 《Surface and interface analysis : SIA》2017,49(4):340-344
Mesoporous silica SBA‐15 was synthesized and silanized with azidopropyl triethoxysilane in order to design a clickable material. Fourier transform infrared analysis permitted to prove the attachment of the azidopropylene groups to SBA‐15 resulting in the reactive and functional material N3‐SBA‐15. X‐ray photoelectron spectroscopy was used to determine the surface composition of SBA‐15. However, we unexpectedly found that the surface bound azido groups undergo X‐ray induced decomposition during the X‐ray photoelectron spectroscopy analysis resulting in the formation of nitrenes. These are very reactive groups able to intercalate C―C and C―H bonds of the propylene chains as judged from the N1s peak shape. Possible mechanisms of intercalation are suggested. C1s and N1s peaks were recorded at different exposure time. N/C, N+/N and N+/C undergo exponential decay. N+/N reaches the value of zero in less than 80 min of exposure to the X‐ray source. The N+/C decay plot was fitted with first‐order kinetics, and the decomposition kinetic constant (kdec) was found to equal to 516.4 s?1. This is a fast X‐ray induced degradation which must be considered with care when examining clickable materials with surface bound alkyl azido groups. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
995.
996.
Sanchita Mondal Saikat Kumar Manna Kalipada Maiti Rajkishor Maji Syed Samim Ali Srimanta Manna 《Supramolecular chemistry》2017,29(8):616-626
A FRET-based chemosensor L containing donor phenanthroline and acceptor fluorescein moiety was designed, synthesised and characterised for the ratiometric fluorescent detection of Cu2+ in organo-aqueous solution. Probe L showed high selectivity and excellent sensitivity towards Cu2+ ions by exhibiting both colorimetric and fluorometric changes due to opening of the spirolactum ring of fluorescein upon complexation with Cu2+. In presence of Cu2+ ions, probe L formed L-Cu2+ complex in 1:1 stoichiometric fashion which is established on the basis of Job’s plot and mass spectroscopy. We also performed DFT computational studies to know the binding nature and coordination feature of the complex. Furthermore, fluorescence imaging studies revealed that probe L was cell permeable and could be used to detect intracellular Cu2+ in living cells. 相似文献
997.
Diltiazem is an established cardiovascular drug mainly used for the management of hypertension specifically for the angina pectoris. Fluoroquinolones are widely prescribed against the treatment of severe infections. In vitro relations of diltiazem with fluoroquinolones (ciprofloxacin, levofloxacin, norfloxacin, and ofloxacin) were examined using spectrophotometric and separation techniques, i.e., RP-HPLC. Diltiazem’s availabilities were observed to be predisposed highly in the presence of fluoroquinolones. To investigate the mechanism of interaction in a variety of dissolution environments, i.e., simulating body environments with regard to pH on these interactions has been studied. Moreover, complex of diltiazem–fluoroquinolones were prepared and elucidated through IR spectroscopy and confirmed by computational molecular modeling. 相似文献
998.
Muhammad Sulaiman Ali Thangamani Arumgam Ravi Subban 《Research on Chemical Intermediates》2017,43(10):5637-5664
Research on Chemical Intermediates - Eight new series of novel phenothiazine-based chalcone derivatives with various N-substituted rhodanines (10a–g to 17a–g) were synthesized by... 相似文献
999.
Zonozi Fatemeh Beyramabadi S. Ali Pordel Mehdi Morsali Ali 《Research on Chemical Intermediates》2017,43(3):1829-1846
Research on Chemical Intermediates - The derivatives of acridine play important roles as dyes, drugs, and antiseptics. Herein, we have investigated the kinetics and the mechanism of the formation... 相似文献
1000.
Chermahini Alireza Najafi Hafizi Hamid Andisheh Nikzad Saraji Mohammad Shahvar Ali 《Research on Chemical Intermediates》2017,43(11):6763-6763
Research on Chemical Intermediates - 相似文献