全文获取类型
收费全文 | 258篇 |
免费 | 10篇 |
国内免费 | 2篇 |
专业分类
化学 | 199篇 |
晶体学 | 9篇 |
力学 | 3篇 |
数学 | 18篇 |
物理学 | 41篇 |
出版年
2024年 | 2篇 |
2023年 | 6篇 |
2022年 | 11篇 |
2021年 | 14篇 |
2020年 | 9篇 |
2019年 | 16篇 |
2018年 | 14篇 |
2017年 | 7篇 |
2016年 | 21篇 |
2015年 | 8篇 |
2014年 | 15篇 |
2013年 | 19篇 |
2012年 | 22篇 |
2011年 | 21篇 |
2010年 | 12篇 |
2009年 | 5篇 |
2008年 | 7篇 |
2007年 | 5篇 |
2006年 | 9篇 |
2005年 | 3篇 |
2004年 | 6篇 |
2003年 | 5篇 |
2002年 | 3篇 |
2001年 | 12篇 |
2000年 | 1篇 |
1999年 | 2篇 |
1997年 | 3篇 |
1996年 | 2篇 |
1995年 | 1篇 |
1994年 | 2篇 |
1993年 | 1篇 |
1991年 | 1篇 |
1989年 | 1篇 |
1985年 | 3篇 |
1980年 | 1篇 |
排序方式: 共有270条查询结果,搜索用时 203 毫秒
101.
Snehlata Yadav Balasubramanian Narasimhan Siong M. Lim Kalavathy Ramasamy Mani Vasudevan Syed Adnan Ali Shah Manikandan Selvaraj 《Chemistry Central journal》2017,11(1):137
Background
A series of 2-(1H-benzo[d]imidazol-2-ylthio)-N-(substituted 4-oxothiazolidin-3-yl) acetamides was synthesized and characterized by physicochemical and spectral means. The synthesized compounds were evaluated for their in vitro antimicrobial activity against Staphylococcus aureus, Bacillus subtilis, Escherichia coli, Candida albicans and Aspergillus niger by tube dilution method. The in vitro cytotoxicity study of the compounds was carried out against human colorectal (HCT116) cell line. The most promising anticancer derivatives (5l, 5k, 5i and 5p) were further docked to study their binding efficacy to the active site of the cyclin-dependent kinase-8.Results
All the compounds possessed significant antimicrobial activity with MIC in the range of 0.007 and 0.061 µM/ml. The cytotoxicity study revealed that almost all the derivatives were potent in inhibiting the growth of HCT116 cell line in comparison to the standard drug 5-fluorouracil. Compounds 5l and 5k (IC50 = 0.00005 and 0.00012 µM/ml, respectively) were highly cytotoxic towards HCT116 cell line in comparison to 5-fluorouracil (IC50 = 0.00615 µM/ml) taken as standard drug.Conclusion
The molecular docking studies of potent anticancer compounds 5l, 5k, 5i and 5p showed their putative binding mode and significant interactions with cyclin-dependent kinase-8 as prospective agents for treating colon cancer.102.
Manikandan S Dhanuskodi S 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2007,67(1):160-165
Single crystals of a non-linear optical (NLO) material 2-amino-5-nitropyridinum L-tartrate (ANPLT) were grown by solvent evaporation technique and characterized by the measurement of density, FT-IR, FT-Raman and X-ray diffraction techniques. Microhardness study and SHG test were also carried out. The EPR spectra were recorded for gamma-irradiated single crystal of ANPLT. The angular variation studies of the spectra were carried out and the principal values of g- and A-tensors were determined. The site symmetry of the radical formed is axial. 相似文献
103.
Ruthenium‐Catalyzed Oxidant‐Free Allylation of Aromatic Ketoximes with Allylic Acetates at Room Temperature 下载免费PDF全文
Rajendran Manikandan Padmaja Madasamy Dr. Masilamani Jeganmohan 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(40):13934-13938
Substituted aromatic ketoximes reacted efficiently with allylic acetates in the presence of {[RuCl2(p‐cymene)]2} and AgSbF6 in 1,2‐dichloroethane at ambient temperature, providing ortho‐allyl aromatic ketoximes in a highly regioselective manner without an oxidant. In the reaction, the acetate group of allyl acetate acts as a base to activate the C?H bond of aromatics. Later, ortho‐allyl aromatic ketoximes were converted into ortho‐allyl aromatic ketones in the presence of HCl. 相似文献
104.
The single crystals of 4-hydroxyacetophenone (4HAP) were grown by the solution growth technique and characterized by X-ray diffraction, UV–VIS, FT-IR, and FT-Raman techniques. TGA–DTA analyses have also been carried out. Electron paramagnetic resonance spectra of γ-irradiated 4HAP were recorded and the spin Hamiltonian parameters were evaluated. 相似文献
105.
Rengaraj S Venkataraj S Tai CW Kim Y Repo E Sillanpää M 《Langmuir : the ACS journal of surfaces and colloids》2011,27(9):5534-5541
Novel template-free hierarchical-like In(2)S(3) hollow microspheres were synthesized using thiosemicarbazide (NH(2)NHCSNH(2)) as both a sulfur source and a capping ligand in a ethanol/water system. In this study, we demonstrate that several process parameters, such as the reaction time and precursor ratio, strongly influence the morphology of the final product. The In(NO(3))(3)/thiosemicarbazide ratios were found to effectively play crucial roles in the morphologies of the hierarchical-like In(2)S(3) hollow microsphere nanostructure. With the ratios increasing from two to four, the In(2)S(3) crystals exhibited almost spherical morphologies. The synthesized products have been characterized by a variety of methods, including X-ray powder diffraction (XRD), Raman spectroscopy, field-emission scanning electron microscopy (FE-SEM), high-resolution transmission electron microscopy (HR-TEM), energy-dispersive X-ray (EDX) analysis, X-ray photoelectron spectroscopy (XPS), and ultraviolet-visible diffused reflectance spectroscopy (UV-vis DRS). XRD analysis confirmed the tetragonal structure of the In(2)S(3) hollow microspheres. The products show complex hierarchical structures assembled from nanoscale building blocks. The morphology evolution can be realized on both outside (surface) and inside (hollow cavity) the microsphere. The surface area analysis showed that the porous In(2)S(3) possesses a specific surface area of 108 m(2)/g and uniform distribution of pore sizes corresponding to the size of pores resulting from the self-assembled structures with flakes. The optical properties of In(2)S(3) were also investigated by UV-vis DRS, which indicated that our In(2)S(3) microsphere samples possess a band gap of ~1.96 eV. Furthermore, the photocatalytic activity studies revealed that the synthesized In(2)S(3) hollow microspheres exhibit an excellent photocatalytic performance in rapidly degrading aqueous methylene blue dye solution under visible light irradiation. These results suggest that In(2)S(3) hollow microspheres will be an interesting candidate for photocatalytic detoxification studies under visible light radiation. 相似文献
106.
In order to explore the possibilities of simulating metallochromism by modern molecular modeling, we apply a sequential hybrid quantum-classical approach to a prototype metallochromic system-the Al(3+) ion and pyrimidinedione (PY) dye complex. The complex shows several structural features with relevance for the metallochromism: the PY dye exhibits conformers with dynamical transitions between twisted structures, which are inhibited by the addition of the metal ion leading to planarization and a conformational arrest: the Al(3+) ion behaves like a structure-modifier for both intra and intermolecular degrees of freedom and with respect to the intermolecular solvation shell structure. The sequential approach that we have employed uses DFT/MM molecular dynamics for structure modeling and TDDFT/PCM for property modeling. The computed metallochromic shift between PY and the Al(PY)(3+) complex in DMSO solvent is obtained in excellent agreement with experiment. The results infer optimism for future use of such modeling techniques to design metallochromic indicators. 相似文献
107.
Nguyen Dinh Phuong Yu Seok Jeong Thangaswamy Selvaraj Sung Kyum Kim Yong Ho Kim Kyung Hwa Jung Jungho Kim Han Dae Yun Sui-Lam Wong Jung-Kul Lee Hoon Kim 《Applied biochemistry and biotechnology》2012,168(2):375-382
XynX of Clostridium thermocellum is a large, multimodular xylanase of 116?kDa. An Escherichia coli transformant carrying the entire xynX produced three active truncated xylanase species of 105, 85, and 64?kDa intracellularly. The Bacillus subtilis WB700 transformant with the xynX, a strain deficient in seven proteases including Vpr, secreted two active truncated xylanase species of 65 and 44?kDa. The B. subtilis WB800 transformant with xynX, a strain deficient in eight proteases including Vpr and WprA, secreted more active enzymes, 8.46?U?ml?1, mostly in the form of 105 and 85?kDa, than the WB700 transformant, 6.93?U?ml?1. This indicates that the additional deletion of wprA enabled the WB800 to secrete XynX in its intact form. B. subtilis WB800 produced more total enzyme activity than E. coli (1,692?±?274 U vs. 141.9?±?27.1 U), and, more importantly, secreted almost all the enzyme activity. The results suggest the potential use of B. subtilis WB800 as a host system for the production of large multimodular proteins. 相似文献
108.
Ayyasami Kathiresan Krishnan Srinivasan Selvaraj Brinda Munirathinam Nethaji Subbaiah Govindarajan 《Transition Metal Chemistry》2012,37(4):393-397
Divalent metal complexes of general formula [M(2-nb)2(mc)2].2(2-nbH), where M = Co(II), Ni(II), Cu(II) or Zn(II), 2-nbH = 2-nitrobenzoic acid and mc = methyl carbazate (NH2NHCOOCH3), have been prepared and characterized by physicochemical and spectroscopic methods. Single-crystal X-ray study of the Cu(II)
complex revealed that the molecule is centrosymmetric, with two N,O-chelating mc ligands in equatorial positions and a pair
of monodentate 2-nb anions in the axial positions. The lattice 2-nbH molecules help to establish the packing of monomers through
hydrogen-bonding interactions. Thermal stability and reactivity of the complexes were studied by TG–DTA. Emission studies
show that these complexes are fluorescent. 相似文献
109.
Ants and humans coexist closely and for the most part happily. We consider ants to be harmless, small beings--we have no problem picking them out of our tea cups or sugar jars, throwing them away and continuing to consume the food. This paper is an eye-opener that these ants are not as harmless as they may seem. In particular, our relationship with those present in bacteria-rich environments (e.g. a microbiological lab) need to be reconsidered. From an analytical point of view we have applied the physical preconcentration coupled ZnO NPs assisted MALDI-MS (PP-MALDI-MS) as a novel and sensitive technique for detecting bacteria on the surface of a species of ant present in our laboratory. The preconcentration methods consist of simple techniques comprising of vortex combined with centrifugation or ultrasonication resulting in increasing sample concentration up to the MALDI-MS detection limit. ZnO NPs were used to further enhance the bacterial signals for culture free rapid analysis using MALDI-MS. The importance of a vortex-combined centrifugation approach, using a large number of samples (large number of ants) and decreasing the suspension volume and addition of sample to ZnO NPs (3.5g L(-1)) were found to be crucial prerequisites for increasing MALDI-MS detection of bacteria on ants. We were able to identify the pathogenic clinically important Staphylococcus aureus on the surface of the ants. The bacterial identification was validated using ClinPro 2.1. 相似文献
110.
Selvaraj Vetrivel Dipak Rana Meenakshi Sundaram Sri Abirami Saraswathi Kumar Divya Noel Jacob Kaleekkal Alagumalai Nagendran 《先进技术聚合物》2019,30(8):1943-1950
Hydrous manganese dioxide (HMO) nanoparticles incorporated cellulose acetate (CA) composite ultrafiltration (UF) membranes are prepared with the aim of improving the water permeation and BSA contaminant removal. The HMO nanoparticles are synthesized from manganese ion and characterized by FT‐IR, XRD, and FESEM. The effect of variation of HMO on CA membranes is probed using FT‐IR, EDAX, contact angle, SEM, and AFM analysis to demonstrate their chemical functionality, hydrophilicity, and morphology. CA/HMO membranes are showing the enhancement in pure water flux (PWF), water uptake, porosity, hydrophilicity, fouling resistance, BSA rejection, and flux recovery ratio (FRR). CA‐1 membrane displayed higher PWF (143.6 Lm2h?1), BSA rejection (95.9%), irreversible fouling (93.3%), and FRR (93.3%). Overall results confirmed that the CA/HMO nanocomposite UF membranes overcome the bottlenecks and shows potential for water treatment applications. 相似文献