全文获取类型
收费全文 | 124篇 |
免费 | 2篇 |
专业分类
化学 | 62篇 |
晶体学 | 2篇 |
力学 | 11篇 |
数学 | 4篇 |
物理学 | 47篇 |
出版年
2023年 | 5篇 |
2022年 | 4篇 |
2020年 | 2篇 |
2019年 | 3篇 |
2018年 | 4篇 |
2017年 | 3篇 |
2016年 | 3篇 |
2015年 | 1篇 |
2014年 | 4篇 |
2013年 | 14篇 |
2012年 | 8篇 |
2011年 | 8篇 |
2010年 | 7篇 |
2009年 | 6篇 |
2008年 | 5篇 |
2007年 | 7篇 |
2006年 | 3篇 |
2005年 | 2篇 |
2004年 | 1篇 |
2003年 | 1篇 |
2001年 | 2篇 |
1998年 | 3篇 |
1996年 | 1篇 |
1995年 | 2篇 |
1994年 | 2篇 |
1993年 | 2篇 |
1992年 | 1篇 |
1990年 | 2篇 |
1989年 | 4篇 |
1986年 | 2篇 |
1985年 | 2篇 |
1984年 | 1篇 |
1980年 | 1篇 |
1978年 | 1篇 |
1976年 | 2篇 |
1974年 | 2篇 |
1973年 | 2篇 |
1972年 | 1篇 |
1971年 | 1篇 |
1964年 | 1篇 |
排序方式: 共有126条查询结果,搜索用时 15 毫秒
71.
R. A. Ganeev H. Singhal P. A. Naik J. A. Chakera M. Tayyab A. K. Srivastava T. S. Dhami M. P. Joshi A. Singh R. Chari S. R. Kumbhare R. P. Kushwaha R. A. Khan R. K. Bhat P. D. Gupta 《Optics and Spectroscopy》2010,108(5):787-803
The wavelength conversion of femtosecond laser pulses in laser plasmas containing clusters of different nature and dimension (fullerenes, metal nanoparticles) is studied. Pulses of a titanium-sapphire laser are used in combination with orthogonally polarized second-harmonic pulses as radiation to be converted. Variations in the generation efficiency of higher harmonics are analyzed under conditions of phase-modulated pulses. It is shown that the optimization of components of a nonlinear optical plasma medium, of plasma excitation conditions by single- and two-color pumps, and of phase and spectral parameters of radiation to be converted leads to a considerable increase in the generation efficiency of higher harmonics. 相似文献
72.
Dwivedi A Mujtaba SF Kushwaha HN Ali D Yadav N Singh SK Ray RS 《Photochemistry and photobiology》2012,88(2):344-355
Levofloxacin (LVFX) is a broad spectrum third generation fluoroquinolone antibiotic, used in the treatment of severe or life-threatening bacterial infections. Photosensitizing mechanism of LVFX was investigated under the ambient environmental intensities of UV-A, UV-B and sunlight exposure. Phototoxic effects of LVFX were assessed on NIH-3T3 and HaCaT cell lines. Results identified first time three photoproducts of LVFX at ambient levels of UV-R by LC-MS/MS. The generation of reactive oxygen species (ROS) was investigated photochemically as well as intracellularly in HaCaT cell line. ROS were significantly quenched by specific quenchers like DABCO, NaN(3), D-mannitol and NAC. Photosensitized LVFX caused lipid peroxidation at different concentrations. Quenching study with superoxide dismutase confirms the LVFX-induced lipid photoperoxidation. Further, photocytotoxicity of LVFX showed significant reduction in cell viability by MTT and neutral red uptake assays. LVFX caused cell arrest in G2/M phases as well as induced apoptosis through ROS-dependent pathway. In addition, photosensitized LVFX also induced upregulation of p21 and Bax/Bcl-2 genes ratio. India is a tropical country and most of the human activities such as agriculture, commerce, sports, etc. take place in bright sunlight; therefore, photosensitive LVFX may lead to skin/ocular disorders and immune suppression. Information is needed regarding the phototoxicity of LVFX for human safety. 相似文献
73.
K. Sandeep Shikha GaurD. Dutta H.S. Kushwaha 《Applied mathematics and computation》2011,218(7):3786-3798
In this paper, two wavelet based adaptive solvers are developed for linear advection-dispersion equation. The localization properties and multilevel structure of the wavelets in the physical space are used for adaptive computational methods for solution of equation which exhibit both smooth and shock-like behaviour. The first framework is based on wavelet-Galerkin and the second is based on multiscale decomposition of finite element method. Coiflet wavelet filter is incorporated in both the methods. The main advantage of both the adaptive methods is the elimination of spurious oscillations at very high Peclet number. 相似文献
74.
An efficient and concise synthesis of 8-amino-2,5-diaryl-1,9,9b-triazaphenalene-4-carbonitriles has been delineated through two successive base catalyzed heteroaromatic annulations of 6-aryl-4-(piperidin-1-yl)-2H-pyran-2-one-3-carbonitriles by guanidine hydrochloride in moderate yield. This reaction was further explored through the ring transformation of 4 with amidines 8 and 11 to afford (2,6-diarylpyrimidin-4-yl)acetonitriles and 6-aryl-4-(piperidine-1-yl)nicotinonitriles in excellent yields. 相似文献
75.
Debanjan Chakraborty Pragalbh Shekhar Himan Dev Singh Rinku Kushwaha C. P. Vinod Ramanathan Vaidhyanathan 《化学:亚洲杂志》2019,14(24):4767-4773
Covalent organic frameworks are a new class of crystalline organic polymers possessing a high surface area and ordered pores. Judicious selection of building blocks leads to strategic heteroatom inclusion into the COF structure. Owing to their high surface area, exceptional stability and molecular tunability, COFs are adopted for various potential applications. The heteroatoms lining in the pores of COF favor synergistic host–guest interaction to enhance a targeted property. In this report, we have synthesized a resorcinol‐phenylenediamine‐based COF which selectively adsorbs CO2 into its micropores (12 Å). The heat of adsorption value (32 kJ mol?1) obtained from the virial model at zero‐loading of CO2 indicates its favorable interaction with the framework. Furthermore, we have anchored small‐sized Ag nanoparticles (≈4–5 nm) on the COF and used the composite for chemical fixation of CO2 to alkylidene cyclic carbonates by reacting with propargyl alcohols under ambient conditions. Ag@COF catalyzes the reaction selectively with an excellent yield of 90 %. Recyclability of the catalyst has been demonstrated up to five consecutive cycles. The post‐catalysis characterizations reveal the integrity of the catalyst even after five reaction cycles. This study emphasizes the ability of COF for simultaneous adsorption and chemical fixation of CO2 into corresponding cyclic carbonates. 相似文献
76.
In this work, we have synthesized Zinc oxide (ZnO) tripods and used its thin film as photoanode in dye-sensitized solar cells. SEM micrographs of the as-prepared sample of ZnO confirmed tripod-like morphology consisting of three cylindrical arms with well-defined ends, joined at a common core. The prepared sample of ZnO tripods was further characterized by EDX, XRD, UV-VIS, and FTIR. The dye N719-sensitized solar cell fabricated with photoanode of ZnO prepared in this work provided the open-circuit photo voltage (V oc)?=?0.558 V, short-circuit photocurrent (J sc)?=?6.368 mA?cm-2, fill factor (FF)?=?0.50, and total conversion efficiency (η)?=?0.88 % under full light illumination (intensity 200 mW?cm?2). When cell was illuminated by visible light (150 mW/cm2), V oc?=?0.546 V, J sc?=?4.437 mA/cm2, FF?=?0.54, and η?=?0.88 % were obtained. 相似文献
77.
Nagsen Gautam Hari Narayan Kushwaha Hemant Kumar Ram Pratap Shio Kumar Singh 《Chromatographia》2011,73(9-10):905-912
This study aimed to develop an LC-MS/MS assay for the quantitation of S002-857 in plasma, urine and feces to evaluate the pharmacokinetic parameters and elimination pathway for further development of S002-857. A sensitive and selective LC-MS/MS method was developed and validated for estimating a novel antidiabetic flavone derivative, S002-857, synthesized by Central Drug Research Institute, CSIR, Lucknow, India. Plasma and urine samples were prepared by two-step liquid-liquid extraction with diethyl ether and feces by protein precipitation using acetonitrile. The analyte was chromatographed on a cyano column with methanol-ammonium acetate buffer (pH 4.6, 10 mM; 90:10, v/v). The calibration curves were linear over a range of 0.78?C400 ng mL?1 for plasma and 1.56?C400 ng mL?1 for urine and feces samples. The accuracy and precision were <15% for plasma, urine and feces samples. The recoveries from spiked plasma, urine and feces samples were >85%. S002-857 was stable in plasma for 8 h at ambient temperature, 30 days at ?60 °C and after three freeze-thaw cycles. The assay was successfully applied to determine the pharmacokinetic parameters and excretion profile in male rats. 相似文献
78.
Conor R. Thomas Girija Sahasrabudhe Satya Kumar Kushwaha Jun Xiong Robert J. Cava Jeffrey Schwartz 《固体物理学:研究快报》2014,8(12):997-1002
The robustness of the Dirac‐like electronic states on the surfaces of topological insulators (TIs) during materials process‐ing is a prerequisite for their eventual device application. Here, the (001) cleavage surfaces of crystals of the topological insulator Bi2Te2Se (BTS) were subjected to several surface chemical modification procedures that are common for electronic materials. Through measurement of Shubnikov–de Hass (SdH) oscillations, which are the most sensitive measure of their quality, the surface states of the treated surfaces were compared to those of pristine BTS that had been exposed to ambient conditions. In each case – surface oxidation, deposition of thin layers of Ti or Zr oxides, or chemical modification of the surface oxides – the robustness of the topological surface electronic states was demonstrated by noting only very small changes in the frequency and amplitude of the SdH oscillations. (© 2014 WILEY‐VCH Verlag GmbH &Co. KGaA, Weinheim) 相似文献
79.
Anupam Patra Jhilik Das Nupur Rani Agrawal Gajraj Singh Kushwaha Mrinmoy Ghosh Young-Ok Son 《Molecules (Basel, Switzerland)》2022,27(21)
An assemblage nexus of microorganisms enclosed in a composite extracellular polymeric matrix is called as a biofilm. The main factor causing biological fouling, or biofouling, is biofilms. Biofilm-mediated biofouling is a significant detrimental issue in several industries, including the maritime environment, industrial facilities, water treatment facilities, and medical implants. Conventional antibacterial remedies cannot wholly eradicate bacterial species owing to the structural rigidity of biofilm and the eventual growth of antibiotic-resistant microorganisms. Consequently, several approaches to disrupt the biofilm have been investigated to address this particular phenomenon. Antimicrobial peptides (AMPs) have emerged as a promising contender in this category, offering several advantages over traditional solutions, including broad-spectrum action and lack of antibiotic resistance. Because biofouling significantly impacts the marine industry, AMPs derived from marine sources may be suitable natural inhibitors of bacterial proliferation. In this article, we discuss the range of physicochemical and structural diversity and the model of action seen in marine AMPs. This makes them an appealing strategy to mitigate biofilm and biofilm-mediated biofouling. This review also systematically summarizes recent research on marine AMPs from vertebrates and invertebrates and their industrial significance, shedding light on developing even better anti-biofouling materials shortly. 相似文献
80.
Abstract A facile, simple, and high-yielding protocol for synthesis of novel glycosyl azetidines was developed from glycosyl β-amino alcohols via intramolecular cyclization under Mitsunobu reaction conditions. 相似文献