全文获取类型
收费全文 | 207篇 |
免费 | 1篇 |
专业分类
化学 | 111篇 |
晶体学 | 13篇 |
力学 | 9篇 |
数学 | 41篇 |
物理学 | 34篇 |
出版年
2022年 | 3篇 |
2019年 | 2篇 |
2018年 | 4篇 |
2017年 | 2篇 |
2016年 | 6篇 |
2015年 | 2篇 |
2014年 | 6篇 |
2013年 | 13篇 |
2012年 | 8篇 |
2011年 | 6篇 |
2010年 | 4篇 |
2009年 | 2篇 |
2008年 | 8篇 |
2007年 | 10篇 |
2006年 | 2篇 |
2003年 | 2篇 |
2001年 | 2篇 |
2000年 | 2篇 |
1995年 | 3篇 |
1994年 | 5篇 |
1993年 | 3篇 |
1992年 | 2篇 |
1991年 | 4篇 |
1990年 | 2篇 |
1989年 | 5篇 |
1988年 | 5篇 |
1987年 | 2篇 |
1986年 | 4篇 |
1984年 | 3篇 |
1983年 | 4篇 |
1982年 | 4篇 |
1981年 | 6篇 |
1980年 | 5篇 |
1979年 | 4篇 |
1978年 | 2篇 |
1977年 | 5篇 |
1976年 | 4篇 |
1975年 | 3篇 |
1974年 | 2篇 |
1973年 | 5篇 |
1970年 | 2篇 |
1968年 | 3篇 |
1964年 | 2篇 |
1962年 | 3篇 |
1960年 | 2篇 |
1959年 | 5篇 |
1958年 | 2篇 |
1954年 | 2篇 |
1945年 | 2篇 |
1935年 | 2篇 |
排序方式: 共有208条查询结果,搜索用时 15 毫秒
91.
G. Saravanan M. Ravikumar M. J. Jadhav M. V. Suryanarayana N. Someswararao P. V. R. Acharyulu 《Chromatographia》2007,66(3-4):291-294
This study deals with a stability indicating HPLC reverse phase method for quantitative determination of temozolomide. A chromatographic
separation was achieved on an Inertsil ODS 3V, 250 × 4.6 mm ID, 5 μm column using mobile phase A (buffer 5 mL glacial acetic
acid in 1,000 mL of Milli Q water ) and mobile phase B (methanol). Forced degradation studies were performed on bulk sample
of temozolomide using acid (0.5 N hydrochloric acid), base (0.5 N sodium hydroxide), oxidation (10% v/v hydrogen peroxide), heat (60 °C) and UV light (254 nm). Degradation of the drug substance was observed in base hydrolysis
and oxidation. Degradation product formed under these conditions was found to be Imp-A. When the stress samples were assayed,
the mass balance was close to 99.5%. The sample solution was stable up to 48 h at 5 °C and mobile phase was found to be stable
up to 48 h at 25 °C. The developed method was validated with respect to linearity, accuracy, precision, robustness and forced
degradation studies prove the stability indicating power of the method. 相似文献
92.
B. Suryanarayana K. Ramanjaneyulu Vemuri Raghavendra N. Murali D. Parajuli S. Yonatan Mulushoa Praveen Choppara P. Anantha Rao Y. Ramakrishna K. Chandramouli 《印度化学会志》2022,99(8):100623
Sm3+ substituted Ni–Co ferrite materials have been developed with the chemical compositions Ni0.5Co0.5Fe2-xSmxO4 for x = 0.0, 0.02, 0.04, and 0.06 by solid-state method. A spinel with a single-phase cubic structure was found through XRD analysis. Crystallite size and lattice parameter fluctuation with Samarium content, decreasing with Sm3+ doping. When Sm3+ is doped, SEM shows a uniform distribution of grains with increasing agglomeration, and the grain size decreases with samarium concentration. Two peaks of absorption mode FTIR spectra show their spinel nature. The samples' negative temperature coefficient measured by the two probe method indicates their semiconducting nature. The DC electrical resistivity of the Ni–Co ferrite system was found to increase from 5.99 × 103 (-cm) to 9.89 × 109 (-cm) as an increase in Sm concentration. VSM measurement gives the saturation magnetization for the concentration up to x = 0.04 decreased and then increased for x = 0.06. All these properties show our samples' higher applicability in various electronic devices. 相似文献
93.
K. Mohan Reddy N. Lingaiah P. S. Sai Prasad I. Suryanarayana 《Journal of solution chemistry》2006,35(3):407-423
Using a potentiometric mass titrationmethod, the pKa values of 12-molybdophosphoric acid (MPA) and 12-tungstophosphoric acid (TPA) were determined in aqueous solution and as
a solid suspension in acetonitrile. The results were compared with the earlier reported values obtained using other methods
like calorimetry and adsorption (Cal-ad). The acidity values in terms of pKa and the number of acid sites were determined for the ammonium salts of MPA and TPA, and ammonium salts incorporated with
vanadium and ammonium salts impregnated on a ZrO2 support. The effect of the amount of the salt or acid in the suspension of acetonitrile on the potentiometric titration behavior
was also studied and it was found that 0.1 g of the substance gives a good neutralization jump in the titration curve. 相似文献
94.
A new simple isocratic chiral RP-LC method has been developed for the separation and quantification of the enantiomer of (R,R)-tadalafil in bulk drugs and dosage forms with an elution time of about 20 min. Chromatographic separation of (R,R)-tadalafil and its enantiomer was achieved on a bonded macro cyclic glycopeptide stationary phase. The method resolves the
(R,R)-tadalafil and its enantiomer with a resolution (R
s) greater than 2.4 in the developed chiral RP-LC. The mobile phase used for the separation and quantification of (R,R)-tadalafil and its enantiomer involves a simple mixture of reverse phase solvents and the cost of analysis was drastically
decreased. The test concentration is 0.4 mg mL−1 in the mobile phase. This method is capable of detecting the enantiomer of (R,R)-tadalafil up to 0.0048 μg wrt test concentration 400 μg mL−1 for a 20 μL injection volume. The drug was subjected to stress conditions of hydrolysis, oxidation, photolysis and thermal
degradation. There was no interference of degradants with (R,R)-tadalafil and its enantiomer in the developed method. The developed chiral RP-LC method was validated with respect to linearity,
accuracy, precision and robustness. The percentage recovery for the enantiomer of (R,R)-tadalafil in bulk drug samples and in dosage forms ranged from 97.0 to 102.5%. The test solution was found to be stable
in the mobile phase for 48 h after preparation. 相似文献
95.
Experiments were conducted in water and wind tunnels on spheres in the Reynolds number range 6 × 103 to 6.5 × 105 to study the effect of natural ventilation on the boundary layer separation and near-wake vortex shedding characteristics.
In the subcritical range of Re (<2 × 105), ventilation caused a marginal downstream shift in the location of laminar boundary layer separation; there was only a small
change in the vortex shedding frequency. In the supercritical range (Re > 4 × 105), ventilation caused a downstream shift in the mean locations of boundary layer separation and reattachment; these lines
showed significant axisymmetry in the presence of venting. No distinct vortex shedding frequency was found. Instead, a dramatic
reduction occurred in the wake unsteadiness at all frequencies. The reduction of wake unsteadiness is consistent with the
reduction in total drag already reported. Based on the present results and those reported earlier, the effects of natural
ventilation on the flow past a sphere can be categorized in two broad regimes, viz., weak and strong interaction regimes.
In the weak interaction regime (subcritical Re), the broad features of the basic sphere are largely unaltered despite the large addition of mass in the near wake. Strong
interaction is promoted by the closer proximity of the inner and outer shear layers at supercritical Re. This results in a modified and steady near-wake flow, characterized by reduced unsteadiness and small drag.
Received: 8 September 1998 / Accepted: 1 January 2000 相似文献
96.
97.
98.
99.
Naik H. Suryanarayana S. V. Murali M. S. Kapote Noy R. 《Journal of Radioanalytical and Nuclear Chemistry》2020,324(1):285-289
Journal of Radioanalytical and Nuclear Chemistry - The production cross section of the medical isotope 68Ga in the 68Zn(p,n)68Ga reaction was measured with the proton energies of... 相似文献
100.