全文获取类型
收费全文 | 1509篇 |
免费 | 81篇 |
国内免费 | 9篇 |
专业分类
化学 | 1153篇 |
晶体学 | 21篇 |
力学 | 42篇 |
数学 | 109篇 |
物理学 | 274篇 |
出版年
2024年 | 13篇 |
2023年 | 28篇 |
2022年 | 28篇 |
2021年 | 111篇 |
2020年 | 40篇 |
2019年 | 64篇 |
2018年 | 57篇 |
2017年 | 55篇 |
2016年 | 91篇 |
2015年 | 61篇 |
2014年 | 78篇 |
2013年 | 99篇 |
2012年 | 132篇 |
2011年 | 127篇 |
2010年 | 74篇 |
2009年 | 53篇 |
2008年 | 72篇 |
2007年 | 70篇 |
2006年 | 66篇 |
2005年 | 71篇 |
2004年 | 45篇 |
2003年 | 38篇 |
2002年 | 21篇 |
2001年 | 7篇 |
2000年 | 6篇 |
1999年 | 4篇 |
1998年 | 2篇 |
1997年 | 3篇 |
1996年 | 5篇 |
1995年 | 6篇 |
1994年 | 5篇 |
1993年 | 2篇 |
1992年 | 5篇 |
1991年 | 3篇 |
1989年 | 6篇 |
1988年 | 3篇 |
1987年 | 4篇 |
1985年 | 3篇 |
1984年 | 4篇 |
1983年 | 4篇 |
1982年 | 2篇 |
1981年 | 12篇 |
1980年 | 4篇 |
1979年 | 3篇 |
1978年 | 2篇 |
1976年 | 2篇 |
1973年 | 2篇 |
1965年 | 1篇 |
1935年 | 1篇 |
1934年 | 1篇 |
排序方式: 共有1599条查询结果,搜索用时 71 毫秒
91.
We image the flow of a nearly random close packed, hard-sphere colloidal suspension (a "paste") in a square capillary using confocal microscopy. The flow consists of a "plug" in the center while shear occurs localized adjacent to the channel walls, reminiscent of yield-stress fluid behavior. However, the observed scaling of the velocity profiles with the flow rate strongly contrasts yield-stress fluid predictions. Instead, the velocity profiles can be captured by a theory of stress fluctuations originally developed for chute flow of dry granular media. We verified this both for smooth and rough walls. 相似文献
92.
Islam Md. Shahidul Alam Md Nur van de Ven Theo. G. M. 《Cellulose (London, England)》2021,28(14):9475-9488
Cellulose - Textile filaments were fabricated from a solution obtained from carboxymethylated cellulose dissolved in aqueous NaOH solution, by wet spinning in an acid coagulation bath. Spinning is... 相似文献
93.
Isa Illyas Md Sharif Sharifah Norain Mohd Hashim Norhayati Ghani Sulaiman Ab 《Ionics》2015,21(10):2949-2958
Ionics - A mercury(II) sensor was developed by using single-walled carbon nanotube (SWCNT) paste electrode modified with layered double Zn/Al hydroxide-3(4-methoxyphenyl)propionate nanocomposite... 相似文献
94.
Lee Chuin Chen Md. Matiur Rahman Kenzo Hiraoka 《Journal of the American Society for Mass Spectrometry》2014,25(11):1862-1869
The heating of electrospray ion source under atmospheric pressure is limited to the normal boiling point of the solution. The boiling takes place when the vapor pressure of the liquid at a given temperature equals the ambient pressure. By using a high pressure ESI source, which has been developed previously in our laboratory, a stable electrospray ionization of super-heated aqueous solution is performed up to a solution temperature of 180°C. The ion source is pressurized with pure nitrogen to a maximum pressure of 11 atm, and it is coupled to a commercial mass spectrometer via a custom-made ion transport capillary. A booster pump with variable pumping speed is added to the pumping system to regulate the pressure in the first pumping stage at 1?~?1.3 Torr. High pressure mass spectrometry is performed on several peptides and proteins to demonstrate its application in the temperature-controlled thermally induced denaturation and dissociation. Graphical Abstract
? 相似文献
95.
Xuan Thang Cao Ali Md Showkat Chan Park Yeong Soon Gal 《Molecular Crystals and Liquid Crystals》2015,618(1):103-110
Poly(?-caprolactone) grafted poly(2-hydroxyethyl methacrylate) functionalized hydroxyapatite (HAP@PHEMA-g-PCL) nanocomposites were synthesized by the combination of reversible addition fragmentation chain transfer (RAFT) polymerization and ring-opening polymerization (ROP). The RAFT agent was anchored on the surface of hydroxyapatite nanocrystals (HAPs) through the silane condensation process of 3-chloropropyltrimethoxysilane followed by reaction with potassium xanthogenate. Poly(2-hydroxyethyl methacrylate) (PHEMA) was covalently functionalized on the surface of HAPs by RAFT polymerization. Then, poly(?-caprolactone) (PCL) was grafted on HAPs by ROP based on the hydroxyl groups of PHEMA to afford HAP@PHEMA-g-PCL. The structure and composition of HAP@PHEMA-g-PCL nanocomposites were characterized by FT-IR, XRD, and TGA analyses. The morphology and formation of the polymer encapsulating HAPs were demonstrated from SEM and TEM images, while the 1H MNR analysis of the cleaved PHEMA-g-PCL confirmed the grafting. 相似文献
96.
The Compressibility of pH‐Sensitive Microgels at the Oil–Water Interface: Higher Charge Leads to Less Repulsion 下载免费PDF全文
Dipl.‐Chem. Karen Geisel Prof. Dr. Lucio Isa Prof. Dr. Walter Richtering 《Angewandte Chemie (International ed. in English)》2014,53(19):4905-4909
pH‐responsive microgels are unique stabilizers for stimuli‐sensitive emulsions that can be broken on demand by changing the pH value. However, recent experiments have indicated that electrostatic interactions play a different role to that in conventional Pickering emulsions. The influence of charges on the interactions between microgels at the oil–water interface is now described. Compression isotherms of microgels with different charge density and architecture were determined in a Langmuir trough, and counter‐intuitive results were obtained: Charged microgels can be compressed more easily than uncharged microgels. The compressibility of microgels is thus not determined by direct Coulomb repulsion. Instead, the different swelling of the microgels in the charged and the uncharged states is proposed to be the key parameter. 相似文献
97.
Md. Azahar Ali Nawab Singh Saurabh Srivastava Ved V. Agrawal Renu John M. Onoda Bansi D. Malhotra 《Applied biochemistry and biotechnology》2014,174(3):926-935
We have fabricated an immunosensor based on carbon nanotubes and chitosan (CNT-CH) composite for detection of low density lipoprotein (LDL) molecules via electrochemical impedance technique. The CNT-CH composite deposited on indium tin oxide (ITO)-coated glass electrode has been used to covalently interact with anti-apolipoprotein B (antibody: AAB) via a co-entrapment method. The biofunctionalization of AAB on carboxylated CNT-CH surface has been confirmed by Fourier transform infrared spectroscopic and electron microscopic studies. The covalent functionalization of antibody on transducer surface reveals higher stability and reproducibility of the fabricated immunosensor. Electrochemical properties of the AAB/CNT-CH/ITO electrode have been investigated using cyclic voltammetric and impedimetric techniques. The impedimetric response of the AAB/CNT-CH/ITO immunoelectrode shows a high sensitivity of 0.953?Ω/(mg/dL)/cm2 in a detection range of 0–120 mg/dL and low detection limit of 12.5 mg/dL with a regression coefficient of 0.996. The observed low value of association constant (0.34 M–1s–1) indicates high affinity of AAB/CNT-CH/ITO immunoelectrode towards LDL molecules. This fabricated immunosensor allows quantitative estimation of LDL concentration with distinguishable variation in the impedance signal. 相似文献
98.
Azmi Mohamed Argo Khoirul Anas Suriani Abu Bakar Azira Abd. Aziz Masanobu Sagisaka Paul Brown Julian Eastoe Azlan Kamari Norhayati Hashim Illyas Md Isa 《Colloid and polymer science》2014,292(11):3013-3023
The performance of single-, double- and triple-chain anionic sulphosuccinate surfactants for dispersing multiwall carbon nanotubes (MWNCTs) in natural rubber latex (NR-latex) was studied using a range of techniques, including field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), thermogravimetric analysis (TGA) and Raman spectroscopy. The conductivities of the nanocomposites were also investigated using four-point probe measurements. Here, MWCNTs were efficiently dispersed in NR-latex with the aid of hyperbranched tri-chain sulphosuccinate anionic surfactants, specifically sodium 1,4-bis(neopentyloxy)-3-(neopentyloxycarbonyl)-1,4-dioxobutane-2-sulphonate (TC14). This paper highlights that TC14 performs much better than that of the commercially available surfactant sodium dodecyl sulphate (SDS), demonstrating how careful consideration of surfactant architecture leads to improved dispersibility of MWCNTs in NR-latex. The results should be of significant interest for improving nanowiring applications suitable for aerospace-based technology. 相似文献
99.
Yusof Enis Nadia Md. Ishak Nurul N. M. Latif Muhammad A. M. Tahir Mohamed I. M. Sakoff Jennette A. Page Alister J. Tiekink Edward R. T. Ravoof Thahira B. S. A. 《Research on Chemical Intermediates》2020,46(4):2351-2379
Research on Chemical Intermediates - A series of tridentate ONS Schiff bases were synthesised via condensation by reacting 2,3-dihydroxybenzaldehyde with S-2-methylbenzyldithiocarbazate (S2MBDTC)... 相似文献
100.
Siti Aini Binti Nordin Mohan Prasath Mani Ahmad Zahran Md Khudzari Ahmad Fauzi Ismail 《International Journal of Polymer Analysis and Characterization》2020,25(3):126-133
AbstractWound healing is a complex process and it involves restoration of damaged skin tissues. Several wound dressings comprising naturally made substances are constantly investigated to assist wound healing. In this research, a new wound dressing based on polyurethane (PU) supplemented with essence of Channa striatus (CS) fish oil was made by electrospinning. Morphological study depicted the reduction in fiber diameter than PU with the addition of fish oil (0.552?±?0.109?μm for 8:1 v/v% and 0.519?±?0.196?μm 7:2 v/v%) than the pristine PU (0.971?±?0.205?µm). Fourier transform infrared spectroscopy (FTIR) analysis revealed the presence of fish oil in the composite as identified through increasing peak intensity. Fish oil resulted in the hydrophilic behavior (88?±?3 (8:1 v/v) and 70?±?6 (7:2 v/v)) as revealed in the contact angle analysis. Thermal gravimetric analysis (TGA) showed the superior thermal behavior of the wound dressing patch compared to the PU. Atomic force microscopy (AFM) analysis insinuated a decrease in the surface roughness of the pristine polyurethane with the added fish oil. Coagulation assays signified the delay in the blood clotting time portraying its anti-thrombogenic behavior. Hemolytic assay revealed the less toxic nature of the developed nanocomposites with the red blood cells (RBC’s) depicting its safety with blood. Hence, polyurethane nanofibers supplemented with fish oil made them as deserving candidates for wound dressing application. 相似文献