全文获取类型
收费全文 | 408篇 |
免费 | 3篇 |
专业分类
化学 | 175篇 |
晶体学 | 5篇 |
力学 | 20篇 |
数学 | 39篇 |
物理学 | 172篇 |
出版年
2022年 | 7篇 |
2018年 | 4篇 |
2017年 | 4篇 |
2016年 | 6篇 |
2015年 | 6篇 |
2014年 | 10篇 |
2013年 | 14篇 |
2012年 | 24篇 |
2011年 | 22篇 |
2010年 | 19篇 |
2009年 | 11篇 |
2008年 | 16篇 |
2007年 | 22篇 |
2006年 | 19篇 |
2005年 | 22篇 |
2004年 | 20篇 |
2003年 | 9篇 |
2002年 | 17篇 |
2001年 | 7篇 |
2000年 | 12篇 |
1999年 | 4篇 |
1998年 | 7篇 |
1997年 | 4篇 |
1996年 | 6篇 |
1995年 | 5篇 |
1994年 | 6篇 |
1993年 | 5篇 |
1992年 | 3篇 |
1991年 | 5篇 |
1989年 | 6篇 |
1987年 | 3篇 |
1986年 | 4篇 |
1985年 | 5篇 |
1984年 | 3篇 |
1983年 | 4篇 |
1982年 | 3篇 |
1981年 | 3篇 |
1978年 | 5篇 |
1976年 | 3篇 |
1975年 | 4篇 |
1974年 | 3篇 |
1973年 | 7篇 |
1971年 | 2篇 |
1970年 | 2篇 |
1965年 | 2篇 |
1964年 | 2篇 |
1946年 | 2篇 |
1945年 | 2篇 |
1944年 | 2篇 |
1943年 | 6篇 |
排序方式: 共有411条查询结果,搜索用时 0 毫秒
31.
32.
Vittal S Shitut NR Kumar TR Vinu MC Mullangi R Srinivas NR 《Biomedical chromatography : BMC》2006,20(11):1252-1259
A simple, sensitive and specific high-performance liquid chromatography method is described for simultaneous determination of rosuvastatin (RST) and gemfibrozil (GFZ) in human plasma using celecoxib as an internal standard (IS). The assay procedure involved extraction of RST, GFZ and IS from plasma into acetonitrile. Following separation and evaporation of the organic layer the residue was reconstituted in the mobile phase and injected onto an X-Terra C(18) column (4.6 x 150 mm, 5.0 microm). The chromatographic run time was less than 20 min using flow gradient (0.0-1.60 mL/min) with a mobile phase consisting of 0.01 M ammonium acetate:acetonitrile:methanol (50:40:10, v/v/v) and UV detection at 275 nm. Nominal retention times of RST, GFZ and IS were 6.7, 13.9 and 16.4 min, respectively. Absolute recovery of both analytes and IS was greater than 90%. The lower limit of quantification (LLOQ) of RST and GFZ was 0.03 and 0.30 microg/mL, respectively. Linearity was excellent (r(2) = 0.999) in the 0.03-10 microg/mL and 0.3-100 microg/mL ranges for RST and GFZ, respectively. The inter- and intra-day precisions in the measurement of RST quality control (QC) samples 0.03, 0.09, 2.50 and 8.00 microg/mL were in the range 2.37-9.78% relative standard deviation (RSD) and 0.92-10.08% RSD, respectively. Similarly, the inter- and intra-day precisions in the measurement of GFZ quality control (QC) samples 0.30, 0.90, 25.0 and 80.0 microg/mL were in the ranges 2.79-6.27 and 0.96-9.69% RSD, respectively. Accuracies in the measurement of QC samples for RST and GFZ were in the range 85.43-107.23 and 84.98-102.35% respectively, of the nominal values. RST and GFZ were stable in the array of stability studies viz., bench-top, auto-sampler and freeze-thaw cycles. Stability of RST and GFZ was established for 1 month at -80C. The application of the assay in an oral pharmacokinetic study in rats co-administered with RST and GFZ is described. 相似文献
33.
34.
35.
We study fluctuations in the force at the boundary of a 2D granular flow. The forces are mainly impulsive at all flow rates. The probability distribution of impulses decays exponentially at large impulses, as do the forces in a static granular medium. At small impulses, the distribution evolves continuously with flow rate with no indication of the transition from collisional flow to intermittently jamming flows. However, the distribution of the time interval between collisions tends to a power law, P(tau) - tau(-3/2), showing a clear dynamical signature of the approach to jamming. 相似文献
36.
K. R.?RajeshEmail author C. S.?Menon 《The European Physical Journal B - Condensed Matter and Complex Systems》2005,47(2):171-176
Sandwich and planar structures were fabricated using
manganese phthalocyanine (MnPc) as active layer and gold (Au) as electrodes
by thermal evaporation method. The permittivity ε of MnPc was determined from
the dependence of capacitance on film thickness. J-V
characteristics of Au/MnPc/Au structure at room temperature were performed.
Thermally generated hole concentration p0, hole
mobility μp, total trap concentration
Nt and depth of the trap level were estimated. The
activation energies of MnPc films were determined from the Arrhenius plots
of ln σ versus 1000/T. The absorption and reflectance spectra of MnPc thin film deposited at room
temperature were recorded in the spectral range 300–900 nm. The optical band
gap of MnPc thin film was determined from the α2 versus hν graph. The optical constants n and k were found. The real and imaginary parts of the optical dielectric constant
ε1
and ε2 were calculated. 相似文献
37.
A. C.?VargheseEmail author C. S.?Menon 《The European Physical Journal B - Condensed Matter and Complex Systems》2005,47(4):485-489
The electrical properties of mixed copper phthalocyanine (CuPc) and nickel
phthalocyanine (NiPc) thin films devices with gold and lead electrodes have
been investigated. The two phthalocyanines were co-evaporated and deposited
on to a pre-cleaned glass substrate by thermal evaporation technique at room
temperature. By the co-sublimation technique an integrated phthalocyanine
sample was prepared. At low voltages the film showed an ohmic conduction
whereas at higher voltage levels the conduction mechanisms were dominated by
space charged limited conduction (SCLC). The value of mobility of holes were
calculated as μ= 3.1×10-8 m2 V-1 s-1
which is lower for the mixed phthalocyanines whereas the trap concentrations
Nt(e) = 8.06 ×1025 m-3 have increased in the SCLC
region. Further the reverse conduction mechanisms have also been
investigated. From the current limitations in the reverse condition a strong
rectifying behaviour was evident. 相似文献
38.
[reaction: see text] Pyridine catalyzes the reaction of 1,2-diaryl diones with dimethyl butynedioate to afford diaroyl maleates. This unprecedented rearrangement involves a unique benzoyl migration and proceeds with complete stereoselectivity. 相似文献
39.
The traditional diffusion theory, often used for isotropic sources, becomes inaccurate at short source-detector spacings and cannot be applied to media with large absorption or with small scattering strengths. We show that for any type of source anisotropy, a Green's-function-based procedure can remove these limitations. The accuracy of the new approach is examined through a comparison with the numerical solution to the radiative transfer equation. 相似文献
40.
We study the statistics of the power flux into a collection of inelastic beads maintained in a fluidized steady state by external mechanical driving. The power shows large fluctuations, including frequent large negative fluctuations, about its average value. The relative probabilities of positive and negative fluctuations in the power flux are in close accord with the fluctuation theorem of Gallavotti and Cohen, even at time scales shorter than those required by the theorem. We also compare an effective temperature that emerges from this analysis to the kinetic granular temperature. 相似文献