全文获取类型
收费全文 | 1405篇 |
免费 | 111篇 |
国内免费 | 13篇 |
专业分类
化学 | 918篇 |
晶体学 | 29篇 |
力学 | 67篇 |
数学 | 113篇 |
物理学 | 402篇 |
出版年
2024年 | 11篇 |
2023年 | 16篇 |
2022年 | 57篇 |
2021年 | 99篇 |
2020年 | 70篇 |
2019年 | 66篇 |
2018年 | 60篇 |
2017年 | 53篇 |
2016年 | 73篇 |
2015年 | 67篇 |
2014年 | 71篇 |
2013年 | 116篇 |
2012年 | 98篇 |
2011年 | 106篇 |
2010年 | 73篇 |
2009年 | 46篇 |
2008年 | 53篇 |
2007年 | 48篇 |
2006年 | 44篇 |
2005年 | 33篇 |
2004年 | 33篇 |
2003年 | 19篇 |
2002年 | 14篇 |
2001年 | 10篇 |
2000年 | 8篇 |
1999年 | 5篇 |
1998年 | 4篇 |
1997年 | 7篇 |
1996年 | 13篇 |
1995年 | 5篇 |
1994年 | 11篇 |
1993年 | 8篇 |
1992年 | 7篇 |
1991年 | 13篇 |
1990年 | 9篇 |
1989年 | 4篇 |
1988年 | 10篇 |
1987年 | 12篇 |
1986年 | 12篇 |
1985年 | 12篇 |
1984年 | 5篇 |
1983年 | 4篇 |
1982年 | 9篇 |
1981年 | 3篇 |
1980年 | 5篇 |
1978年 | 3篇 |
1977年 | 5篇 |
1974年 | 4篇 |
1973年 | 5篇 |
1971年 | 2篇 |
排序方式: 共有1529条查询结果,搜索用时 46 毫秒
71.
Fabrication of Sensitive Potentiometric Cholesterol Biosensor Based on Co3O4 Interconnected Nanowires 下载免费PDF全文
Highly sensitive, selective, reliable and inexpensive cholesterol biosensors are highly demanded for the routine monitoring of cholesterol molecules in order to prevent heart failure incidents. In this study, Co3O4 nanostructures are synthesized using polyvinyl pyrrolidone surfactant as growth template by a low temperature aqueous chemical growth method. The morphology of nanostructures was investigated by scanning electron microscopy and X‐ray diffraction techniques. The nanostructures exhibit interconnected nanowires like morphology with interconnected network of nanowires. The nanostructures of Co3O4 are polycrystalline. The cholesterol oxidase was physically adsorbed on the interconnected nanowires of Co3O4 for the chemical sensing of cholesterol molecules. The sensor device detected a wide range of cholesterol from 1×10?7 M to 1×10?3 M concentrations with sensitivity of ?94.031 mV/decade. A detection limit of 0.035×10?7 M cholesterol concentration was observed and a fast response time of 10 s was also noticed. The fabricated device is highly stable, selective, sensitive, reproducible and repeatable. All the collected information about presented cholesterol biosensor indicates its potential application for the monitoring of cholesterol concentrations from human blood serum and real‐life samples. 相似文献
72.
S. Hussain I. U. Khan M. Akkurt S. Ahmad M. N. Tahir 《Russian Journal of Coordination Chemistry》2014,40(9):686-694
Two novel homobinuclear ytterbium(III) complexes, [Yb2(2AMB)6(H2O)4] · 2C2H6O (I) and Yb2(3AMB)6(H2O)4] · 3H2O (II) (2AMB = 2-aminobenzoic acid, 3AMB = 3-aminobenzoic acid) have been synthesized and characterized by elemental analysis, infrared spectroscopy, thermogravimetric analysis and X-ray crystallography (CIF files CCDC nos. 950103 (I), 921652 (II)). Complex I crystallizes in triclinic space group \(P\bar 1\) and complex II crystallizes in monoclinic space group P21/n. X-ray analysis shows that both complexes (I, II) have the dinuclear structure. The central Yb3+ ions in both complexes are eight-coordinated adopting distorted YbO8 dodecahedral geometry. Each Yb3+ ion is coordinated to two O atoms from bridging carboxylate, four O atoms from the chelating carboxylate ligands and two O atoms of water molecules. The crystal structure of I and II are stabilized by N-H…O, O-H…O, O-H…N, and C-H…O hydrogen bonds, C-H…π interactions and weak π-π stacking interactions. 相似文献
73.
Alam Perwez Siddiqui Nasir Ali Al-Rehaily Adnan J. Alajmi Mohamed Fahad Basudan Omar Ahmed Khan Tajdar Hussain 《平面色谱法杂志一现代薄层色谱法》2014,27(3):204-209
JPC – Journal of Planar Chromatography – Modern TLC - A simple, sensitive, and stability-indicating high-performance thinlayer chromatography (HPTLC)-densitometric method was developed... 相似文献
74.
Highly Tin‐Selective Stille Coupling: Synthesis of a Polymer Containing a Stannole in the Main Chain 下载免费PDF全文
Julian Linshoeft Evan J. Baum Andreas Hussain Dr. Paul J. Gates Prof. Dr. Christian Näther Prof. Dr. Anne Staubitz 《Angewandte Chemie (International ed. in English)》2014,53(47):12916-12920
The incorporation of heavier Group 14 element heteroles into semiconducting polymers leads to unusual optoelectronic properties. However, polymers containing stannoles have not been accessible to date. We report a synthetic route to a well‐defined, stannole‐containing polymer, the first example of this class of π‐conjugated polymers. This route was made possible by developing difunctionalized stannole monomers and highly tin‐selective Stille coupling reactions that leave the tin in the stannole untouched. Compared to poly(3‐n‐hexylthiophene), the resulting polymer displays a remarkable bathochromic shift in its absorption. 相似文献
75.
Nosrati Sahar Molavipordanjani Sajjad Emami Saeed Abedi Seyed Mohammad Talebpour Amiri Fereshteh Hosseinimehr Seyed Jalal 《Journal of Radioanalytical and Nuclear Chemistry》2020,323(1):205-211
This study presents [99mTc]BPTG-1 and [99mTc]BPTG-2 for glioblastoma imaging. In vitro cellular uptakes of these radiotracers were examined in SKOV-3, MCF-7, U87-MG, HT-29, and A549 cell lines. U87-MG cell line displayed the highest radiotracers uptakes. Biodistribution study in U87-MG tumor bearing mice revealed higher uptake of radiotracers in tumor than muscle and brain. Liver, intestine, and kidneys displayed the highest radioactivity uptakes. The main route of radiotracers elimination was hepatobiliary. Due to the brain uptake of these radiotracers, they are promising radiotracers for future studies in the diagnosis of glioblastoma.
相似文献76.
4-Amino-1,2,4-triazolium nitrate (4-ATN) is an energetic and non-sensitive ionic liquid, which was introduced as a good candidate in previous works for the replacement of 2,4,6-trinitrotoluene (TNT) in melt-cast explosives. Since previous studies used pure nitric acid for nitration of 4-ATN, the effect of the use of low price industrial nitric acids (50 %, 70 % and 98 %) is investigated on the percent yields of 4-ATN. The thermogravimetric and differential scanning calorimetry (TGA/DSC) are done on the synthesized 4-ATN with impure nitric acid at a heating rate of 10 K · min–1 by the vacuum system. The obtained TGA/DSC curves confirm decomposition of 4-ATN involving melting and dissociation. Derivative thermogravimetric (DTG) curves of 4-ATN at various heating rates are applied to obtain activation energy of thermolysis by several model-free techniques. The calculated activation energies are in the range 78.7–87.7 kJ · mol–1, which are about 10 kJ · mol–1 more than the reported activation energy of industrial TNT (purity 98.2 %), i.e. 66–70 kJ · mol–1. Assessments of detonation performance of 4-ATN are also compared with TNT, which show higher detonation performance of 4-ATN. Thus, 4-ATN can be used with nitramine compounds as melt-cast explosives with higher thermal stability and detonation performance than corresponding nitramine compound/TNT explosives. 相似文献
77.
Khoja Asif Hussain Anwar Mustafa Shakir Sehar Mehran Muhammad Taqi Mazhar Arslan Javed Adeel Amin Nor Aishah Saidina 《Research on Chemical Intermediates》2020,46(8):3817-3833
Research on Chemical Intermediates - The excess emission of greenhouse gases (GHGs) such as CO2 and CH4 is posing an acute threat to the environment, and efficient ways are being sought to utilize... 相似文献
78.
Saurav Goel Sara Hawi Gaurav Goel Vijay Kumar Thakur Anupam Agrawal Clare Hoskins Oliver Pearce Tanvir Hussain Hari M. Upadhyaya Graham Cross Asa H. Barber 《Materials Today Chemistry》2020
The world is witnessing tumultuous times as major economic powers including the US, UK, Russia, India, and most of Europe continue to be in a state of lockdown. The worst-hit sectors due to this lockdown are sales, production (manufacturing), transport (aerospace and automotive) and tourism. Lockdowns became necessary as a preventive measure to avoid the spread of the contagious and infectious “Coronavirus Disease 2019” (COVID-19). This newly identified disease is caused by a new strain of the virus being referred to as Severe Acute Respiratory Syndrome CoronaVirus 2 (SARS CoV-2; formerly called 2019-nCoV). We review the current medical and manufacturing response to COVID-19, including advances in instrumentation, sensing, use of lasers, fumigation chambers and development of novel tools such as lab-on-the-chip using combinatorial additive and subtractive manufacturing techniques and use of molecular modelling and molecular docking in drug and vaccine discovery. We also offer perspectives on future considerations on climate change, outsourced versus indigenous manufacturing, automation, and antimicrobial resistance. Overall, this paper attempts to identify key areas where manufacturing can be employed to address societal challenges such as COVID-19. 相似文献
79.
Herein, we report an approach to combat counterfeiting and storage of valuable information based on the solid‐state fluorescence switching behavior of isoniazid functionalized naphthalene diimide (ISO_NDI) in response to an external stimuli (i. e., HCl vapor). The unique feature of ISO_NDI is further utilized to develop an invisible ink (ISO_NDI‐PVA) with commercial polymer polyvinyl alcohol (PVA). A solid‐state fluorescence recovery was observed while loading with HCl vapors. This exclusive property of the material could be applied directly as a security ink for confidential data storage purpose. Based on above strategy, we successfully realized the rewritable application by using ISO_NDI‐PVA ink and confirm its practical efficacy on various substrates by creating different patterns. The solid‐state fluorescence switching behavior of ISO_NDI‐PVA ink exhibited reversible on/off signal for multiple cycles under the influence of HCl/NH3 vapors. Mechanistic investigation supports a clear participation of intermolecular charge transfer (ICT) phenomenon in the solid‐state fluorescence switching property. The ease of fabricating the ink with invisible to visible characteristics in response to HCl vapors provides new opportunities for exploring the application of ISO_NDI‐PVA as invisible ink for targeted security applications. 相似文献
80.
Mubashir Hassan Balasaheb D. Vanjare Kyou-Yeong Sim Hussain Raza Ki Hwan Lee Saba Shahzadi Andrzej Kloczkowski 《Molecules (Basel, Switzerland)》2022,27(5)
A series of nine novel 1,2,4-triazole based compounds were synthesized through a multistep reaction pathway and their structures were scrutinized by using spectral methods such as FTIR, LC-MS, 1H NMR, and 13C NMR. The synthesized derivatives were screened for inhibitory activity against the mushroom tyrosinase and we found that all the synthesized compounds demonstrated decent inhibitory activity against tyrosinase. However, among the series of compounds, N-(4-fluorophenyl)-2-(5-(2-fluorophenyl)-4-(4-fluorophenyl)-4H-1,2,4-triazol-3-ylthio) acetamide exhibited more prominent activity when accompanied with the standard drug kojic acid. Furthermore, the molecular docking studies identified the interaction profile of all synthesized derivatives at the active site of tyrosinase. Based on these results, N-(4-fluorophenyl)-2-(5-(2-fluorophenyl)-4-(4-fluorophenyl)-4H-1,2,4-triazol-3-ylthio) acetamide could be used as a novel scaffold to design some new drugs against melanogenesis. 相似文献