全文获取类型
收费全文 | 513篇 |
免费 | 36篇 |
国内免费 | 11篇 |
专业分类
化学 | 372篇 |
晶体学 | 2篇 |
力学 | 25篇 |
数学 | 59篇 |
物理学 | 102篇 |
出版年
2023年 | 3篇 |
2022年 | 7篇 |
2021年 | 33篇 |
2020年 | 35篇 |
2019年 | 24篇 |
2018年 | 36篇 |
2017年 | 28篇 |
2016年 | 39篇 |
2015年 | 23篇 |
2014年 | 37篇 |
2013年 | 52篇 |
2012年 | 46篇 |
2011年 | 55篇 |
2010年 | 33篇 |
2009年 | 31篇 |
2008年 | 23篇 |
2007年 | 19篇 |
2006年 | 8篇 |
2005年 | 6篇 |
2004年 | 5篇 |
2003年 | 1篇 |
2002年 | 3篇 |
2001年 | 3篇 |
2000年 | 2篇 |
1998年 | 1篇 |
1993年 | 2篇 |
1992年 | 2篇 |
1978年 | 1篇 |
1966年 | 1篇 |
1932年 | 1篇 |
排序方式: 共有560条查询结果,搜索用时 78 毫秒
551.
E. Tazikeh Lemeski G. Rezaei Behbehani A. A. Saboury M. Monajjemi R. Zafar Mehrabian M. Ahmadi Golsefidi H. Rajabzadeh M. T. Baei S. Hasanzadeh 《Journal of solution chemistry》2011,40(4):575-586
The interaction of human growth hormone (hGH) with the divalent mercury ion was studied by isothermal titration calorimetry
at two temperatures of 27 °C and 37 °C in aqueous solutions. We found that there is a set of two identical and non-interacting
binding sites for Hg2+ ions. The intrinsic dissociation equilibrium constant and the molar enthalpy of binding are 4.2 mmol⋅L−1 and −14.8 kJ⋅mol−1 at 27 °C and 5.1 mmol⋅L−1 and −14.2 kJ⋅mol−1 at 37 °C, respectively. The results obtained indicate that the stability of the protein increases due to the binding of mercury
ions using the extended solvation theory. 相似文献
552.
A thermodynamic study of the interaction of bovine carbonic anhydrase II, CAII, with zinc ion was carried out by using isothermal
titration calorimetry (ITC) at 300, 310 and 320 K in Tris buffer solutions at pH=7.5. The heats of Zn2++ CAII interaction are reported and analyzed in terms of the new solvation theory. It was indicated that there are three identical
and non-cooperative sites on CAII for Zn2+. The binding of a zinc ion is exothermic with dissociation equilibrium constants of 78.32, 95.81 and 116.70 mmol⋅L−1 at 300, 310 and 320 K respectively. 相似文献
553.
The initiation of atherosclerosis involves retention of colloidal atherogenic lipoproteins, primarily low density lipoprotein (LDL), in the arterial intima. This retention occurs when LDL binds to smooth muscle cell extracellular matrix (SMC ECM), and is enhanced by lipoprotein lipase (LpL) and sphingomyelinase (Smase). Here we use a fluorescence assay and dynamic light scattering to study the individual and combined effects of these two enzymes on LDL aggregation. Our results show: (1) LpL is self-sufficient to induce LDL aggregation with aggregate sizes up to ~400 nm; (2) Smase induces LDL aggregation due to generation of ceramide and subsequent hydrophobic interactions; (3) Smase hydrolysis of LpL-induced LDL aggregates does not cause further aggregation and results in a ~3-fold diminished production of ceramide, while LpL treatment of Smase-induced aggregates does enhance aggregation; (4) The simultaneous addition of LpL and Smase causes increased variability in aggregation with final sizes ranging from 50 to 110 nm. Our data suggest a new proatherogenic function for LpL, namely, bridging between LDL particles causing their aggregation and consequently enhanced retention by SMC ECM. The mechanism of LpL-and-Smase-mediated LDL aggregation and binding to SMC ECM provides specific points of intervention to design novel effective antiatherogenic therapeutics. 相似文献
554.
A one-pot synthesis of imidazo[1,2-a]pyridines is described. Benzyl halides or benzyl tosylates are oxidized to aldehydes under mild Kornblum conditions which then undergo a three-component reaction with various 2-aminopyridines and isocyanides to afford the imidazo[1,2-a]pyridines in excellent yields. 相似文献
555.
A simple and convenient procedure for the synthesis of nitriles by dehydration of aldoxime using supported sulphuric acid on melamine-formaldehyde resin(MFR) under solvent-free condition has been developed.A variety of aromatic and aliphatic aldoximes were converted to the corresponding nitriles.The resin was recovered and reused for subsequent reactions. 相似文献
556.
A thermodynamic study on the interaction of myelin basic protein with mercury ion was studied by using isothermal titration calonmetry,ITC,at 300.15,310.15 and 320.15 K in Tris buffer solution at pH 7.The enthalpies of MBP + Hg2+ interaction are reported and analysed in terms of the extended solvation model.It was found that MBP has two identical and non-cooperative binding sites for Hg2+ ions.The intrinsic dissociation equilibrium constants are 99.904,112.968 and 126.724μmol/L,and the molar enthalpy of binding are -11.634,-10.768 and -10.117kJ mol-1 at 300.15,310.15 and 320.15 K,respectively. 相似文献
557.
This presented study is to make comparison of cross sections to produce 117Sb and 90Nb via different reactions with particle incident energy up to 70 MeV as a part of systematic studies on particle-induced activations on enriched Sn, Y2O3 and ZrO2 targets, theoretical calculation of production yield, calculation of required thickness of target and suggestion of optimum reaction to produce Antimony-117 and Niobium-90. 相似文献
558.
One-dimensional Jacobian elliptic quasi-exactly solvable second-order differential equations are obtained by introducing the
generalized third master functions. It is shown that the solutions of these differential equations are generating functions
for a new set of polynomials in terms of energy with factorization property. The roots of these polynomials are the same as
the eigenvalues of the differential equations. Some one-dimensional elliptic quasi-exactly quantum solvable models are obtained
from these differential equations.
相似文献
559.
Milad Reshadi Mohammad Hassan Saidi Abbas Ebrahimi 《Theoretical and Computational Fluid Dynamics》2018,32(1):1-21
This paper presents an analysis of the combined electro-osmotic and pressure-driven axial flows of viscoelastic fluids in a rectangular microchannel with arbitrary aspect ratios. The rheological behavior of the fluid is described by the complete form of Phan-Thien–Tanner (PTT) model with the Gordon–Schowalter convected derivative which covers the upper convected Maxwell, Johnson–Segalman and FENE-P models. Our numerical simulation is based on the computation of 2D Poisson–Boltzmann, Cauchy momentum and PTT constitutive equations. The solution of these governing nonlinear coupled set of equations is obtained by using the second-order central finite difference method in a non-uniform grid system and is verified against 1D analytical solution of the velocity profile with less than 0.06% relative error. Also, a parametric study is carried out to investigate the effect of channel aspect ratio (width to height), wall zeta potential and the Debye–Hückel parameter on 2D velocity profile, volumetric flow rate and the Poiseuille number in the mixed EO/PD flows of viscoelastic fluids with different Weissenberg numbers. Our results show that, for low channel aspect ratios, the previous 1D analytical models underestimate the velocity profile at the channel half-width centerline in the case of favorable pressure gradients and overestimate it in the case of adverse pressure gradients. The results reveal that the inapplicability of the Debye–Hückel approximation at high zeta potentials is more significant for higher Weissenberg number fluids. Also, it is found that, under the specified values of electrokinetic parameters, there is a threshold for velocity scale ratio in which the Poiseuille number is approximately independent of channel aspect ratio. 相似文献
560.