全文获取类型
收费全文 | 84篇 |
免费 | 8篇 |
国内免费 | 1篇 |
专业分类
化学 | 67篇 |
力学 | 7篇 |
数学 | 6篇 |
物理学 | 13篇 |
出版年
2024年 | 1篇 |
2023年 | 1篇 |
2022年 | 9篇 |
2021年 | 7篇 |
2020年 | 4篇 |
2019年 | 4篇 |
2018年 | 4篇 |
2017年 | 2篇 |
2016年 | 4篇 |
2015年 | 4篇 |
2014年 | 6篇 |
2013年 | 5篇 |
2012年 | 5篇 |
2009年 | 3篇 |
2008年 | 1篇 |
2007年 | 3篇 |
2006年 | 7篇 |
2005年 | 2篇 |
2004年 | 3篇 |
2003年 | 3篇 |
2002年 | 3篇 |
2001年 | 2篇 |
1995年 | 2篇 |
1991年 | 1篇 |
1990年 | 2篇 |
1985年 | 1篇 |
1984年 | 1篇 |
1978年 | 2篇 |
1977年 | 1篇 |
排序方式: 共有93条查询结果,搜索用时 312 毫秒
41.
42.
The two-dimensional (2D) motion of the Jeffrey fluid by the curved stretching sheet coiled in a circle is investigated. The non-Fourier heat flux model is used for the heat transfer analysis. Feasible similarity variables are used to transform the highly nonlinear ordinary equations to partial differential equations (PDEs). The homotopy technique is used for the convergence of the velocity and temperature equations. The effects of the involved parameters on the physical properties of the fluid are described graphically. The results show that the curvature parameter is an increasing function of velocity and temperature, and the temperature is a decreasing function of the thermal relaxation time. Besides, the Deborah number has a reverse effect on the pressure and surface drag force. 相似文献
43.
Fahad Hussain Fahad Imtiaz Rahman Poushali Saha Atsushi Mikami Takashi Osawa Satoshi Obika S. M. Abdur Rahman 《Molecules (Basel, Switzerland)》2022,27(11)
Chemical modification of sugars and nucleosides has a long history of producing compounds with improved selectivity and efficacy. In this study, several modified sugars (2–3) and ribonucleoside analogs (4–8) have been synthesized from α-d-glucose in a total of 21 steps. The compounds were tested for peripheral anti-nociceptive characteristics in the acetic acid-induced writhing assay in mice, where compounds 2, 7, and 8 showed a significant reduction in the number of writhes by 56%, 62%, and 63%, respectively. The compounds were also tested for their cytotoxic potential against human HeLa cell line via trypan blue dye exclusion test followed by cell counting kit-8 (CCK-8) assay. Compound 6 demonstrated significant cytotoxic activity with an IC50 value of 54 µg/mL. Molecular docking simulations revealed that compounds 2, 7, and 8 had a comparable binding affinity to cyclooxygenase-1 (COX-1) and cyclooxygenase-2 (COX-2) enzymes. Additionally, the bridged nucleoside analogs 7 and 8 potently inhibited adenosine kinase enzyme as well, which indicates an alternate mechanistic pathway behind their anti-nociceptive action. Cytotoxic compound 6 demonstrated strong docking with cancer drug targets human cytidine deaminase, proto-oncogene tyrosine-protein kinase Src, human thymidine kinase 1, human thymidylate synthase, and human adenosine deaminase 2. This is the first ever reporting of the synthesis and analgesic property of compound 8 and the cytotoxic potential of compound 6. 相似文献
44.
M. N. Cheema I. H. Qureshi M. Ashraf Imtiaz Hanif 《Journal of Radioanalytical and Nuclear Chemistry》1977,35(2):311-319
Extraction behaviour of the chelates of group VB–VIIB and VIII elements using 1-(2-pyridylazo)-2-naphthol (PAN) has been studied
as a function of pH. Studies have been made to back-extract the metal ions from the organic phase into the aqueous solution
containing the optimum concentration of KCN and HClO4 and buffers of appropriate pH. The masking agents such as citrate, cyanide, thiosulphate, fluoride and thiourea were used
to achieve more specific separations. The studies indicate the potentiality of PAN as a useful solvent extracting reagent
in devising group chemical separation procedures for activation analysis. 相似文献
45.
Imtiaz Hanif J. Hanif R. Qadeer M. Zafar Iqbal 《Journal of Radioanalytical and Nuclear Chemistry》1995,191(2):305-314
Estimation of strontium has been studied by wavelength dispersive X-ray fluorescence spectrometery (WDXRF) as an analytical technique using Sr K as an analytical line. Lower limits of detection, precision, and intensities were plotted against counting time and concentrations to assess optimum time for measurement, expected scatter of the results, and calibration curves for intensity to concentration relationship. For its assessment the best equations determined by regression and least squares fitting along with a standard multiple addition technique were applied to a complex fuel admixture and simulated nuclear fuel solutions at a bum up of 650 GJ/Kg after a 0.5-year cooling time. 相似文献
46.
Habib‐ur‐Rehman Mohammad Shakirullah Imtiaz Ahmad Sher Shah Hameedullah 《中国化学会会志》2006,53(5):1045-1052
Sawdust of Dalbergia sissoo, a byproduct of sawmills, was found to be a promising adsorbent for the removal of nickel ions from aqueous solution. Sorption of nickel ions onto sawdust of Dalbergia sissoo was studied using the batch technique. Kinetics studies show that nickel ions sorption process obeys a first order rate law. The applicability of the Langmuir and Freundlich models for the data was tested. Both the models adequately describe the experimental data of the biosorption of nickel ions. The sorption capacities and energies were calculated. Langmuir parameters Xm and K1 were found to increase with rise in temperature; Freundlich constants 1/n and Kf have been evaluated for 293K, 303K, 313K and 323K. Thermodynamic parameter ΔH° = 4.80 kJ mol?;1 shows that sorption of nickel ions onto sawdust is an endothermic process. 相似文献
47.
48.
Rapid Aqueous Late‐Stage Radiolabelling of [GaF3(BnMe2‐tacn)] by 18F/19F Isotopic Exchange: Towards New PET Imaging Probes
下载免费PDF全文
![点击此处可从《Angewandte Chemie (International ed. in English)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Francesco M. Monzittu Imtiaz Khan Prof. William Levason Dr. Sajinder K. Luthra Dr. Graeme McRobbie Prof. Gillian Reid 《Angewandte Chemie (International ed. in English)》2018,57(22):6658-6661
A simple and rapid method for 18F radiolabelling of [GaF3(BnMe2‐tacn)] by 18F/19F isotopic exchange is described. The use of MeCN/H2O or EtOH/H2O (75:25) and aqueous [18F]F? (up to 200 MBq) with heating (80 °C, 10 min) gave 66±4 % 18F incorporation at a concentration of 268 nm , and 37±5 % 18F incorporation at even lower concentration (27 nm ), without the need for a Lewis acid promoter. A solid‐phase extraction method was established to give [Ga18F19F2(BnMe2‐tacn)] in 99 % radiochemical purity in an EtOH/H2O mixture. 相似文献
49.
Sobia Imtiaz Muhammad Siddiq Ayesha Kausar Sedra Tul Muntha Jaweria Ambreen Iram Bibi 《高分子科学》2018,36(4):445-461
Carbon nanotubes (CNTs) have long been recognized as the stiffest and strongest man-made material known to date.In addition,their high electrical conductivity has roused interest in the areas of electrical appliances and communication related applications.However,due to their miniature size,the excellent properties of these nanostructures can only be exploited if they are homogeneously embedded into light-weight matrices as those offered by a whole series of engineering polymers.In order to enhance their chemical affinity to engineering polymer matrices,chemical modification of the graphitic sidewalls and tips is necessary.The mechanical and electrical properties to date of a whole range of nanocomposites of various carbon nanotube contents are also reviewed in this attempt to facilitate progress in this emerging area.Recently,carbonaceous nano-fillers such as graphene and carbon nanotubes (CNTs) play a promising role due to their better structural and functional properties and broad range of applications in every field.Since CNTs usually form stabilized bundles due to van der Waals interactions,they are extremely difficult to disperse and align in a polymer matrix.The biggest issues in the preparation of CNTs reinforced composites reside in efficient dispersion of CNTs into a polymer matrix,the assessment of the dispersion,and the alignment and control of the CNTs in the matrix.An overview of various CNT functionalization methods is given.In particular,CNT functionalization using click chemistry and the preparation of CNT composites employing hyperbranched polymers are stressed as potential techniques to achieve good CNT dispersion.In addition,discussions on mechanical,thermal,electrical,electrochemical and applications ofpolymer/CNT composites are also included. 相似文献
50.
Catalytic efficiency of some novel nanostructured heterogeneous solid catalysts in pyrolysis of HDPE
Imtiaz Ahmad M. Ismail Khan M. Ishaq Hizbullah Khan Kashif Gul Waqas Ahmad 《Polymer Degradation and Stability》2013
In the present study, the catalytic conversion of high density polyethylene (HDPE) to useful products has been investigated in the presence of BaTiO3 based catalysts in a micro steel reactor at 350 °C and 30 min reaction time. The catalysts, including BaTiO3, Pb/BaTiO3, Co/BaTiO3 and Pb–Co/BaTiO3 were prepared in the laboratory by reactive calcination method and characterized by Scanning Electron Microscopy (SEM), Energy Dispersive X-rays (EDX), Surface Area Analyzer (SAA) and X-rays Diffractometry (XRD). The product yields (over all yields and yields of liquid, gas and coke/residue) as a function of individual catalyst concentration was studied. The result indicated a promising effect of the catalysts used on conversion to liquid products and their composition in term of carbon range (C6 – >C30) & hydrocarbon group types (paraffin's, olefins, naphthenics, and aromatics). Among the catalysts used, Pb–Co/BaTiO3 gave the maximum yield of liquid products (86%) when used in 1 wt % loading. The same catalyst gave the average yield (20–25%) of different range hydrocarbons i.e. C6–C12, C13–C16, C17–C20 and C20–C30. Inversely, the un-doped BaTiO3, favored the formation of C6–C12 and C13–C16 range hydrocarbons, whereas Pb doped BaTiO3 and Co doped BaTiO3 enhanced the yield of C13–C16, and C20–C30 range hydrocarbons. Regarding the hydrocarbon group types, all catalysts significantly increased the formation of paraffins and reduced olefins and naphthenes. 相似文献