全文获取类型
收费全文 | 137篇 |
免费 | 4篇 |
专业分类
化学 | 70篇 |
晶体学 | 3篇 |
力学 | 8篇 |
数学 | 5篇 |
物理学 | 55篇 |
出版年
2023年 | 6篇 |
2022年 | 3篇 |
2021年 | 4篇 |
2020年 | 3篇 |
2019年 | 1篇 |
2018年 | 2篇 |
2017年 | 3篇 |
2016年 | 2篇 |
2015年 | 5篇 |
2014年 | 2篇 |
2013年 | 11篇 |
2012年 | 13篇 |
2011年 | 15篇 |
2010年 | 8篇 |
2009年 | 9篇 |
2008年 | 8篇 |
2007年 | 5篇 |
2006年 | 3篇 |
2005年 | 2篇 |
2004年 | 6篇 |
2003年 | 4篇 |
2002年 | 5篇 |
2001年 | 3篇 |
2000年 | 2篇 |
1999年 | 2篇 |
1997年 | 1篇 |
1996年 | 1篇 |
1994年 | 1篇 |
1992年 | 1篇 |
1991年 | 1篇 |
1990年 | 3篇 |
1988年 | 1篇 |
1984年 | 1篇 |
1973年 | 1篇 |
1943年 | 1篇 |
1930年 | 1篇 |
1928年 | 1篇 |
排序方式: 共有141条查询结果,搜索用时 15 毫秒
1.
Toshiro Watanabe Tapan Kumar Mazumder Shiro Nagai Keisuke Tsuji Shigeru Terabe 《Analytical sciences》2003,19(1):159-161
A micellar electrokinetic chromatography (MEKC) method was developed for estimating the angiotensin-I converting enzyme (ACE) inhibitory activity by separating the hippuric acid liberated in the ACE reaction mixture in the presence of an inhibitor, captopril. The hippuric acid was successfully separated and detected by MEKC with a 25 mM sodium dodecyl sulfate solution in a 25 mM phosphate-50 mM borate buffer at pH 7.0; the total analysis took about 5 min. A good linear relationship was observed between the inhibitor and the peak area of hippuric acid release. No significant difference in the ACE inhibitory activity (IC50) of captopril (an antihypertensive medicine) or autolyzed-mushrooms (functional foods) was observed between the conventional method and the MEKC method. The MEKC method was found to be a useful technique for a rapid assay of the ACE inhibitory activity. 相似文献
2.
This paper deals with the small-angle neutron scattering (SANS) investigation on solution-quenched PH13-8 Mo stainless steel.
From the nature of the variation of the functionality of the profiles for varying specimen thickness and also from the transmission
electron microscopy (TEM), it has been established that the small-angle scattering signal predominantly originates from the
block-like metallic carbide precipitates in the specimen. The contribution due to double Bragg reflection is not significant
in the present case. The single scattering profile has been extracted from the experimental profiles corresponding to different
values of specimen thickness. In order to avoid complexity and non-uniqueness of the multi-parameter minimization for randomly
oriented polydisperse block-like precipitate model, the data have been analyzed assuming randomly oriented polydisperse cylindrical
particle model with a locked aspect ratio. 相似文献
3.
Kinshuk Dasgupta D. Sen T. Mazumdar R. K. Lenka R. Tewari S. Mazumder J. B. Joshi S. Banerjee 《Journal of nanoparticle research》2012,14(3):728
For the first time, bamboo-shaped multiwalled carbon nanotubes, having diameter of the order of 50 nm, have been grown on
carbon black in a fluidized bed in bulk amount. The activation energy for the synthesis of the product was found out to be
around 33 kJ/mol in the temperature range of 700−900 °C. The carbon nanotubes were separated from the carbon black by preferential
oxidation of the later, the temperature of which was determined by thermogravimetry. The transmission electron microscopy
revealed different features of the nanotubes such as “Y” junction, bend, and catalyst filling inside the nanotubes. Small
angle neutron scattering was performed on the nanotubes synthesized at different temperatures. The data were fitted into a
suitable model in order to find out the average diameter, which decreases with increase in synthesis temperature. The Monte
Carlo simulation predicts the same behavior. Based on the above observations, a possible growth mechanism has been predicted.
The oscillation in carbon saturation value inside the catalyst in the fluidized bed has been indicated as the responsible
factor for the bamboo-shaped structure. 相似文献
4.
We present a novel mechanism of pattern formation behind a flat interface during directional solidification of peritectic alloys. It is shown through computational modeling that irregular oscillatory thermosolutal convection can develop in the vertical Bridgman system, even with bottom seeding and bottom cooling. The coupling of the flow oscillation near the interface with solidification leads to ordered layered structures in the solidified crystal, which agree closely with earlier experimental results. 相似文献
5.
The mechanism of action of inosine-uridine nucleoside hydrolase has been investigated by long-term molecular dynamics (MD) simulation in TIP3P water using stochastic boundary conditions. Five MD studies have been performed with enzyme substrate complex (E.S), enzyme substrate complex with protonated His241 (EH.S), enzyme transition state complex (E.TS), enzyme transition state complex with protonated His241 (EH.TS), and His241Ala transition state complex E(H241A).TS. Special attention has been given to the role of His241, which has been considered as the general acid catalyst to assist departure of the leaving nucleobase on the basis of its location in the active site in the X-ray crystal structure (). Yet on the basis of the location in the active site, Tyr229 is closer to the aniline ring of pAPIR as compared to His241. On initiation of MD simulations, His241 does not approach the nucleobase in the structures of EH.S, E.S, EH.TS, and E.TS. In the solvated enzyme, Tyr229, which is a member of the hydrogen bonding network inosine O2'.Asp14.His241.Tyr229.inosine N7, serves as a proton source to the leaving nucleobase. The loss of significant activity of His241Ala mutant is shown to be related to the disruption of the above hydrogen bonded network and the distancing of Tyr229 from inosine N7. The structures of the enzyme complexes with substrate or TS are not visibly altered on protonation of His241, a most unusual outcome. The bell-shaped pH dependence upon pK(app)'s of 7.1 and 9.1 may be attributed to the necessity of the dissociation of Asp10 or Asp15 and the acid form of Tyr229, respectively. In TS, the residue Ile81 migrated closer, whereas Arg233 moved away from the nucleobase. The probability of ribooxocarbenium ion stabilization by Asn168 and Asp14 is discussed. The Asp14-CO(2)(-) is hydrogen bonded to the ribose 2'-OH for 96% of the MD simulation time. Nucleophilic addition of water138 to ribooxocarbenium ion is suggested to be assisted by the proton shuttle from water138 --> Asp10 --> Asp15 --> water pool. An anticorrelation motion between Tyr229-OH and Asn168-OD1 in EH.S and E.S is observed. The relationship of this anticorrelated motion to mechanism, if any, deserves further exploration, perhaps the formation of a near attack conformation. 相似文献
6.
The generalized Langevin model, which is used to model the motion of stochastic particles in the velocity–composition joint probability density function (PDF) method for reacting turbulent flows, has been extended to incorporate solid wall effects. Anisotropy of Reynolds stresses in the near-wall region has been addressed. Numerical experiments have been performed to demonstrate that the forces in the near-wall region of a turbulent flow cause the stochastic particles approachi ng a solid wall to reverse their direction of motion normal to the wall and thereby, leave the near-wall layer. This new boundary treatment has subsequently been implemented in a full-scale problem to prove its validity. The test problem considered here is that of an isothermal, non-reacting turbulent flow in a two-dimensional channel with plug inflow and a fixed back-pressure. An efficient pressure correction method, developed in the spirit of the PISO algorithm, has been implemented. The pressure correction strategy is easy to implement and is completely consistent with the time- marching scheme used for the solution of the Lagrangian momentum equations. The results show remarkable agreement with both k–ϵ and algebraic Reynolds stress model calculations for the primary velocity. The secondary flow velocity and the turbulent moments are in better agreement with the algebraic Reynolds stress model predictions than the k– ϵ predictions. © 1997 by John Wiley & Sons, Ltd. 相似文献
7.
Nairwita Mazumder Ritabrata Biswas Subenoy Chakraborty 《General Relativity and Gravitation》2011,43(6):1827-1836
Here we consider our universe as inhomogeneous spherically symmetric Lema
[^(i)]{\hat{i}}
tre−Tolman−Bondi Model and analyze the thermodynamics of this model of the universe. The trapping horizon is calculated and is found to coincide
with the apparent horizon. The Einstein field equations are shown to be equivalent with the unified first law of thermodynamics.
Finally assuming the first law of thermodynamics validity of the generalized second law of thermodynamics is examined at the
apparent horizon for the perfect fluid and at the event horizon for holographic dark energy. 相似文献
8.
A set of coupled differential equations obtained by Wanas in the Mikhail-Wanas generalized field theory is completely integrated. 相似文献
9.
NirmlaDevi Thakur Vilas G. Gaikar Debasis Sen Subhasish Mazumder Nancy S. Pandita 《Analytical letters》2017,50(4):690-711
A green method using Juglans regia bark extract was used to synthesize silver nanoparticles at room temperature with monitoring by absorption spectroscopy. The size and shape of the synthesized nanoparticles were characterized by infrared spectroscopy, transmission electron microscopy, scanning electron microscopy, high-resolution transmission electron microscopy, and small-angle X-ray scattering. The average particle size was from 10 to 30?nm. Gas chromatography–mass spectrometry (GC–MS) was used for the separation, identification, and quantification of components of the plant extracts. A possible mechanism for the synthesis of nanoparticles was elucidated based on the GC–MS results. The synthesized silver nanoparticles showed effective inhibition against Streptococcus mutans, which is the main causative agent for dental caries. The nanoparticles also showed promising antibiofilm activity by inhibiting the glucosyltransferase enzyme. 相似文献
10.
Nairwita Mazumder Subenoy Chakraborty 《International Journal of Theoretical Physics》2011,50(1):251-259
In this paper, we investigate the validity of the generalized second law of thermodynamics of the universe bounded by the
event horizon. Here we consider homogeneous and isotropic model of the universe filled with perfect fluid in one case and
in another case holographic model of the universe has been considered. In the third case the matter in the universe is taken
in the form of non-interacting two fluid system as holographic dark energy and dust. Here we study the above cases in the
Modified gravity, f(R) gravity. 相似文献