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排序方式: 共有382条查询结果,搜索用时 290 毫秒
61.
Surbhi Grewal Pravesh Kumar Dr. Saonli Roy Dr. Indu Bala Dr. Chitranjan Sah Dr. Santanu Kumar Pal Dr. Sugumar Venkataramani 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(19):e202104602
Two tripodal C3-symmetric photoswitchable molecular systems T1 and T2 are reported that have extended conjugation at external and internal positions using an acryl group. The influence of the extended π-bonds in their absorption properties, thermal relaxation of the photoisomers and their propensities in forming supramolecular self-assemblies have been explored through spectroscopy, and microscopic studies. In particular, the investigations on the self-assembly have been carried out using scanning electron microscopy (SEM), transmission electron microscopy (TEM), polarized optical microscopy (POM), X-ray diffraction studies (XRD) and atomic force microscopy (AFM). Remarkably, the position of the acryl group influences the behaviour of the two target molecules in supramolecular assembly, and also in the formation of photoresponsive organic hydrogels or microcrystals. 相似文献
62.
Manisha Soni Chandra Prakash Rajesh Dabur Vijay Kumar 《Applied biochemistry and biotechnology》2018,186(1):27-39
The present study reports beneficial effect of hydroxytyrosol (HT) against arsenic (As)-induced oxidative stress in the rat brain. Rats were orally administered with sodium arsenite dissolved in distilled water (25 ppm, by oral gavage) for 8 weeks or HT (10 mg/kg b. wt.) in combination with As. Results showed increase in protein oxidation and lipid peroxidation, while catalase and superoxide dismutase (SOD) activities as well as GSH content were decreased after As exposure in rat brain. Fourier transform infrared analysis showed significant alteration in peak area values that also validated the oxidative damage to lipids and proteins. In addition, As exposure caused increase in protein expression of caspase-3 and Bax, while Bcl-2 expression was downregulated resulting in translocation of cytochrome c from mitochondria to cytosol. Treatment of HT with As reversed protein oxidation, lipid peroxidation, and increased GSH content as well as catalase and SOD activities. Administration of HT also prevented translocation of cytochrome c from mitochondria and increased mitochondria/cytosol ratio of cytochrome c. Hence, treatment of HT with As improved antioxidant system and efficiently lowered the generation of oxidative stress in rat brain. 相似文献
63.
A vacuum membrane distillation (VMD) model has been developed and validated with experimental data. The model consists of an extended transport model for the VMD process and is able to predict the effects of concentration and temperature polarization on the overall process performance. To validate the model, first it was tested with few experimental case studies from literature [S. Bandini, G.G. Sarti, Heat and mass transport resistances in vacuum membrane distillation per drop, AIChE J. 45 (7) (1999) 1422–1433; K.W. Lawson, D.R. Lloyd, Membrane distillation. I. Module design and performance evaluation using vacuum membrane distillation, J. Membr. Sci. 120 (1996) 111–121; A.M. Urtiaga, G. Ruiz, I. Ortiz, Kinetic analysis of the vacuum membrane distillation of chloroform from aqueous solutions, J. Membr. Sci. 165 (2000) 99–110]. Then the VMD model has been validated with experimental data collected from the recovery of aroma compounds from black currant [R.B. Jørgensen, A.S. Meyer, C. Varming, G. Jonsson, Recovery of volatile aroma compounds from black currant juice by vacuum membrane distillation, J. Food Eng. 64 (2004) 23–31]. In this work, recovery of 12 characteristic volatile aroma compounds from black currant juice has been studied. The simulated results from the VMD model, in terms of aroma concentration in the permeate have been compared with those obtained from laboratory experiments. The validated model has been used to study the effects of various process and membrane parameters on the concentration factor. The physical properties of various aroma compounds have been predicted using group contribution method as a function of temperature. 相似文献
64.
Swarbhanu Sarkar Yeong Su Ha Nisarg Soni Gwang Il An Woonghee Lee Min Hwan Kim Phuong Tu Huynh Heesu Ahn Nikunj Bhatt Yong Jin Lee Jung Young Kim Kwon Moo Park Isao Ishii Shin‐Geol Kang Jeongsoo Yoo 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2016,128(32):9511-9516
Hydrogen sulfide (H2S) has multifunctional roles as a gas signaling molecule in living systems. However, the efficient detection and imaging of H2S in live animals is very challenging. Herein, we report the first radioisotope‐based immobilization technique for the detection, quantification, and in vivo imaging of endogenous H2S. Macrocyclic 64Cu complexes that instantly reacted with gaseous H2S to form insoluble 64CuS in a highly sensitive and selective manner were prepared. The H2S concentration in biological samples was measured by a thin‐layer radiochromatography method. When 64Cu–cyclen was injected into mice, an elevated H2S concentration in the inflamed paw was clearly visualized and quantified by Cerenkov luminescence and positron emission tomography (PET) imaging. PET imaging was also able to pinpoint increased H2S levels in a millimeter‐sized infarcted lesion of the rat heart. 相似文献
65.
Possible modes of deactivation of Jacobsen's Co-salen catalyst during the hydrolytic kinetic resolution (HKR) of epichlorohydrin were explored by UV-vis spectroscopy, X-ray absorption spectroscopy, and electrospray ionization mass spectrometry, combined with recycling studies. Although an active Co(III)-salen catalyst deactivated substantially after multiple cycles without regeneration, the catalyst maintained its +3 oxidation state throughout the runs. Thus, deactivation of Co-salen during HKR was not the result of Co reduction. The mass spectrum of a deactivated material showed that catalyst dimerization does not account for the loss of activity. Results from various catalyst pretreatment tests, as well as from catalysts containing various counterions (acetate, tosylate, chloride, iodide) indicated that the rate of addition of the Co-salen counterions to epoxide forming Co-OH during the reaction correlated with deactivation. The extent of counterion addition to epoxide was influenced by the exposure time and the nucleophilicity of the counterion. An oligo(cyclooctene)-supported Co-OAc salen catalyst, which was 25 times more active than the standard Co-salen catalyst, was recycled multiple times with negligible deactivation. 相似文献
66.
R. K. Bamezai A. Soni Z. Vakhovskaya H. Kresse 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2009,83(13):2283-2287
Two binary phase diagrams of the liquid crystals (4-n-pentylphenyl-4-n-hexyloxybenzoate (PPHB) with 4-nitrophenyl-4-n-pentylbenzoate (NPPB) and 4-n-hexyloxyphenyl-4-n-decyloxybenzoate (HPDB) with NPPB) have been studied. PPHB shows only a nematic phase where as for HPDB trimorphism, with
the SmC, SmA and nematic phases, was observed. Substance NPPB which has a strong polar nitro group is non-mesogenic one. Both
the phase diagrams show an induction and stabilization of SmA phase and appearance of the nematic state in the high concentration
range of polar component. The dielectric measurements confirm the phase transition temperatures and show changes in the short
range interaction at the phase transitions. 相似文献
67.
Sarvendra Kumar Surbhi M. K. Yadav 《Russian Journal of Physical Chemistry B, Focus on Physics》2018,12(3):383-393
The FTIR and FT-Raman spectra of tetrahydroxy-1,4quinone hydrate have been recorded in the regions 4000–400 and 3500–50 cm–1 respectively. Using the observed Fourier-transform infrared spectroscopy (FTIR) and FT-Raman data, a complete vibrational assignment and analysis of the fundamental modes of the compound has been carried out. The optimum molecular geometry, harmonic vibrational frequencies, infrared intensities and Raman scattering activities, were calculated by the density functional theory (DFT/B3LYP) and Hartree–Fock (HF) method with 6-311+G(d,p) basis set. The difference between the observed and scaled wavenumber values of most of the fundamental vibrations is very small. A detailed interpretation of the infrared and Raman spectra of tetrahydroxy-1,4quinone hydrate is also reported. The calculated HOMO and LUMO energies show that charge transfer occurs within the molecule. 相似文献
68.
Vijay Singh Jun-Jie Zhu Manoj Tiwari Manish Soni Mahendra Aynayas Seok-Hee Hyun R. Narayanan Manoj Mohapatra V. Natarajan 《Journal of Non》2009,355(50-51):2491-2495
Strong blue-green light emitting Eu doped SrAl2O4 phosphor was synthesized by a low-temperature initiated, self-propagating and gas producing combustion process in a very short time (<5 min). The prepared powder was characterized by X-ray diffraction, Fourier-transform infrared spectrometry and scanning electron microscopy. The excitation spectrum shows a peak at 397 nm. Upon excitation at 397 nm, the emission spectrum exhibits a well defined broad band with maximum at 493 nm corresponding to 4f65d → 4f7 transition. Electron paramagnetic resonance (EPR) measurements at X-band showed low field signals due to Eu2+ ions in SrAl2O4:Eu. 相似文献
69.
N. Dixit N. Anasane M. Chavda D. Bodas H. P. Soni 《Crystal Research and Technology》2012,47(10):1105-1112
We have reported the synthesis of cubic (zinc blende) phase ZnS: Ni2+ nanoparticles using a simple wet‐chemical method. Synthesized ZnS: Ni2+ nanoparticles had been characterized by X‐ray diffraction (XRD) and Energy Dispersive X‐ray (EDX) analysis. Surface morphologies were studied using Scanning Electron Microscopy (SEM). Fourier Transform Infrared (FTIR) spectra of selected samples were also carried out to confirm the presence of capping agent on the surface of the material. We have demonstrated that various morphologies like spherical, tetrapods, sheet and long‐armed multipods are emerged by simple chemical route without any vigorous reaction parameters and changing the concentration of dopant ions only. The probable mechanism for such morphologies has also been suggested. 相似文献
70.
Trichloromethyl phenyl ketone benzoylates primary and secondary aliphatic alcoholic groups in compounds also containing a phenolic group in the presence of 2–10 mol % of PMDETA organocatalyst at room temperature in high yields and excellent selectivity. It also shows the potential to selectively benzoylate primary alcoholic groups of aminoarylalkanols and primary-secondary diols as well as primary amino group of alkyl amines in the presence of aryl amines under similar conditions. A rationale for the selectivity and efficiency of the reaction has been provided. 相似文献