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231.
This paper investigates the efficiency of the organic acids on the pretreatment of an industrially generated cotton gin waste for the removal of lignin, thereby releasing cellulose and hemicellulose as fermentable sugar components. Cotton gin waste was pretreated with various organic acids namely lactic acid, oxalic acid, citric acid, and maleic acid. Among these, maleic acid was found to be the most efficient producing maximum xylose sugar (126.05?±?0.74 g/g) at the optimum pretreatment condition of 150 °C, 500 mM, and 45 min. The pretreatment efficiency was comparable to the conventional dilute sulfuric acid pretreatment. A lignin removal of 88% was achieved by treating maleic acid pretreated biomass in a mixture of sodium sulfite and sodium chlorite. The pretreated biomass was further evaluated for the release of sugar by enzymatic hydrolysis and subsequently bioethanol production from hydrolysates. The maximum 686.13 g/g saccharification yield was achieved with maleic acid pretreated biomass which was slightly higher than the sulfuric acid (675.26 g/g) pretreated waste. The fermentation of mixed hydrolysates(41.75 g/l) produced 18.74 g/l bioethanol concentration with 2.25 g/l/h ethanol productivity and 0.48 g/g ethanol yield using sequential use of Saccharomyces cerevisiae and Pichia stipitis yeast strains. The production of bioethanol was higher than the ethanol produced using co-culture in comparison to sequential culture. Thus, it has been demonstrated that the maleic acid pretreatment and fermentation using sequential use of yeast strains are efficient for bioethanol production from cotton gin waste. 相似文献
232.
Chen G Pramanik BN Bartner PL Saksena AK Gross ML 《Journal of the American Society for Mass Spectrometry》2002,13(11):1313-1321
Electrospray ionization (ESI) quadrupole ion-trap tandem mass spectrometry (MS/MS) was utilized to characterize a class of complex oligosaccharide antibiotics (everninomicins) that include SCH 27899, everninomicin-D, amino everninomicin (SCH 27900), and SCH 49088 (containing a hydroxylamino-ether sugar). The addition of sodium chloride (approximately 1 microg/mL) facilitates the formation of abundant metal complex ions, and this was used because protonation does not readily occur for most of these compounds. The multiple-stage mass analysis (MS(n)) of the sodiated species provides an important series of fragment ions that are specific for sugar sequence and for some sugar-ring opening. These data suggest a general charge-remote fragmentation pattern with the sodium cation residing in a specific, central location of the sugar chain and fragmentation occurring to trim the end of the molecule. For protonated everninomicin (SCH 27900), however, the proton appears to be mobile during the collisional activation process, opening different fragmentation pathways depending on the proton location. The use of water and acetonitrile with 0.1% acetic acid as the solvent in ESI-MS promotes rapid hydrolysis of the central ortho ester, resulting in the formation of abundant sodiated products that are hydrated. These product ions of the hydrated molecules are likely formed by the same charge-remote fragmentation processes as those that occur for the unhydrolyzed precursor. 相似文献
233.
Das PK Pramanik R Bagchi S 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2003,59(8):1681-1688
Solvation characteristics in homogeneous and heterogeneous media have been probed by monitoring the band width of ICT band of 2,6-di-phenyl-4(2,4,6-triphenyl-1-pyridino) phenolate, the indicator solute for E(T)(30) scale, in pure, mixed binary solvents and aqueous micellar solution. Non-ideal solvation behaviour is observed in all the binary solvent mixtures. Index of preferential solvation has been calculated as a function of solvent composition. Study in micellar media indicates that the dye is located at the micelle-water interface. The effects of variation of micelle concentration, temperature and electrolyte concentration have also been studies. 相似文献
234.
Shannigrahi M Pramanik R Bagchi S 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2003,59(13):2921-2933
Solvation characteristics in homogenous (pure and mixed binary solvents) and heterogeneous media (aqueous micelles, beta- and gamma-cyclodextrine solutions) have been studied by monitoring the emission characteristics of a newly synthesised dye. The longest wavelength absorption and emission band of the dye arise due to transition between S(0) and S(1) state. The maximum energy of electronic transition involving intramolecular charge transfer is found to be dependent on both the hydrogen-bond donating ability and the polarity-polarisability in pure solvent. The dipole moment in the S(1) state, as determined by solvatochromic procedure, agrees well with the value obtained by theoretical calculation at the AM1 level. Preferential solvation of the dye by alcohols has been found to occur in ethanol+water, propan-1-ol+water, propan-2-ol+water binary mixtures. In aqueous micellar media the dye molecule is located at the water-micelle interface. The binding constant for the dye-micelle interaction has also been determined. The results have been compared with those for a structurally related symmetrical ketocyanine dye. 相似文献
235.
A. K. Pramanik 《Meccanica》1979,14(3):145-150
Summary This paper studies the effect of variation of velocity of the oscillatory surface pressure distribution over a finite time interval t0 on the wave generated from rest. The result of such an acceleration is found to produce the same steady state wave system as it would be if the pressure started impulsively with the uniform velocity at t=t0. The effect of initial acceleration is felt in the transient part of the wave system.
Sommario Questa memoria studia l'effetto della variazione di velocità di una distribuzione oscillatoria di pressione superficiale in un intervallo di tempo finito t0, sull'onda generata a partire dalla quiete. Si trova che questa accelerazione produce lo stesso sistema di onde di regime che si avrebbe se la pressione iniziasse complessivamente con velocità uniforme al tempo t=t0. L'effetto dell'accelerazione iniziale è sentito nella parte transitoria del sistema di onde.相似文献
236.
Sudip Biswas Dipanjan Chakraborty Rashmita Das Rajib Bandyopadhyay Panchanan Pramanik 《Analytica chimica acta》2015
Graphite paste electrode modified with nitrogen doped porous carbon (NDPC) is used for the detections of paracetamol (PCM), ascorbic acid (AA) and p-aminophenol (PAP) at relatively low concentration. NDPC is synthesized by direct carbonization of Zn(OAc)2 incorporated melamine-formaldehyde resin microsphere. The NDPC shows small pore diameters centered at 3.14 nm and 8.12 nm and has a pseudo graphitic structure with reasonable porous matrix. The lower limit of detections (S/N = 3) for PCM, AA, and PAP are found to be 30 nM, 720 nM and 10 nM respectively. Under optimized experimental condition, the linear ranges of determination for PCM and AA are 1–400 μM, 10–2700 μM respectively in mixture. Similarly for PCM and PAP mixture, the linear ranges of determination are found to be 1–90 μM. It is also used for the analysis of urine and pharmaceutical products with better sensitivity. 相似文献
237.
Controlled Synthesis of Highly Crystallized Mesoporous Mn2O3 and Mn3O4 by Using Anionic Surfactants 下载免费PDF全文
Palani Raja Jothi Dr. Malay Pramanik Dr. Cuiling Li Prof. Shanthi Kannan Dr. Victor Malgras Dr. Rahul R. Salunkhe Prof. Yusuke Yamauchi 《化学:亚洲杂志》2016,11(5):667-673
Mesostructured manganese oxide (Mn3O4) is prepared by a soft‐templating method employing sodium dodecyl sulfate (SDS) as a structure‐directing agent. By removing the template from the as‐prepared mesostructured Mn3O4 by extraction or calcination, we successfully synthesized highly crystallized mesoporous Mn3O4 or Mn2O3, respectively, with different crystalline structures. 相似文献
238.
Anamika Pramanik Malay Kumar Das Vĕra Hamplová Miroslav Kašpar Alexej Bubnov 《Phase Transitions》2015,88(7):745-757
The effect of several polar ester linkage groups incorporated in the molecular core of a chiral lactic acid derivative on self-assembling properties has been investigated by polarizing optical microscopy, small angle X-ray diffraction, differential scanning calorimetry, optical and electro--optical studies. The compound possesses the paraelectric smectic A* (SmA*) and ferroelectric smectic C* (SmC*) phases over a broad temperature range. Mesomorphic behaviour, spontaneous polarization, birefringence, optical transmission, dielectric anisotropy and structural properties of the self-assembled chiral material have been determined. The obtained results are discussed and compared with that of other liquid crystalline materials. Experimentally determined spontaneous polarization and tilt angle values are also used to elucidate the nature of SmC* to SmA* phase transition. The effect of polar ester linkages in the molecular core has also been discussed. 相似文献
239.
The formation of a series of Cu(II), Zn(II) and Cd(II) complexes using the p-substituted aryl azo system has been reported. Presence of electron donating –Me, –OMe groups impart some unusual coordination behaviors in Cu(II) complexes. Varying coordination mode and electron density in the ligand results in the formation of an unusual Cu–S bond in complex 1 and an unusual equatorial coordination of H2O in Cu(II) complex 2 with a square-pyramidal geometry.The hydrogen bonding site along with the metal coordination site in the ligand results in the formation of higher dimensional self-assembled supramolecular architectures. Compatibility of the hard–soft nature of the metal ion and symbiosis effect of the ligand with metal is responsible for the formation of long range higher dimensional networks in the solid-state, which were confirmed by single crystal X-ray structure analysis. Furthermore, various physicochemical studies, viz. thermal behaviors, absorption spectra, electrochemistry and EPR studies, have been conducted to rationalize the structures in the solution phase. 相似文献
240.
The quantum numbers labelling the basis states and the corresponding strong coupled wavefunctions in the SU BF (3) ? U F (2j + 1) limit of interacting boson — fermion — fermion model are given. This dynamical symmetry limit is appropriate for heavy deformed odd — odd nuclei for configurations with one of the odd particle (proton or neutron) occupying all the natural parity orbits in the corresponding valence shell and the other particle occupying a single j — orbit. A boson — fermion — fermion interaction that can change the positions of the strong coupled bands without admixing and generate degenerate quadruplet of bands is constructed. A simple spin — spin and spin — orbital interaction that splits and changes the positions of the members of the quadruplet of bands is given. Adding a coriolis term to the hamiltonian generates doubly decoupled bands such as those seen in 176Re nucleus. 相似文献