全文获取类型
收费全文 | 84篇 |
免费 | 2篇 |
专业分类
化学 | 55篇 |
晶体学 | 1篇 |
力学 | 1篇 |
数学 | 7篇 |
物理学 | 22篇 |
出版年
2020年 | 1篇 |
2019年 | 3篇 |
2017年 | 1篇 |
2016年 | 2篇 |
2014年 | 1篇 |
2013年 | 3篇 |
2011年 | 4篇 |
2009年 | 2篇 |
2008年 | 2篇 |
2007年 | 2篇 |
2006年 | 1篇 |
2005年 | 2篇 |
2004年 | 1篇 |
2003年 | 2篇 |
2002年 | 1篇 |
2000年 | 1篇 |
1999年 | 1篇 |
1997年 | 2篇 |
1996年 | 1篇 |
1995年 | 2篇 |
1993年 | 1篇 |
1992年 | 2篇 |
1991年 | 2篇 |
1990年 | 2篇 |
1989年 | 6篇 |
1988年 | 3篇 |
1986年 | 1篇 |
1985年 | 3篇 |
1984年 | 4篇 |
1982年 | 4篇 |
1980年 | 3篇 |
1978年 | 2篇 |
1977年 | 2篇 |
1976年 | 2篇 |
1975年 | 4篇 |
1974年 | 2篇 |
1973年 | 4篇 |
1969年 | 2篇 |
1928年 | 2篇 |
排序方式: 共有86条查询结果,搜索用时 15 毫秒
1.
The determination of doxazosin by high-performance liquid chromatography with fluorescence detection is described. Propanolol was used as the internal standard. Plasma samples were treated with methanol to precipitate the proteins. Doxazosin was isolated with C18 reversed-phase extraction columns. The determination limit is 1 ng/ml of plasma, while the extraction columns can be reused frequently. The method is applied to clinical trial samples. 相似文献
2.
3.
A quality check for an automated system of analyzing large sets of neutron activated samples has been developed. Activated
samples are counted with an HPGe detector, in conjunction with an automated sample changer and spectral analysis tools, controlled
by the Canberra GENIE 2K and REXX software. After each sample is acquired and analyzed, a Microsoft Visual Basic program imports
the results into a template Microsoft Excel file where the final concentrations, uncertainties, and detection limits are determined.
Standard reference materials are included in each set of 40 samples as a standard quality assurance/quality control (QA/QC)
test. A select group of sample spectra are also visually reviewed to check the peak fitting routines. A reference spectrum
was generated in MCNP 4c2 using an F8, pulse-height, tally with a detector model of the actual detector used in counting.
The detector model matches the detector resolution, energy calibration, and counting geometry. The generated spectrum also
contained a radioisotope matrix that was similar to what was expected in the samples. This spectrum can then be put through
the automated system and analyzed along with the other samples. The automated results are then compared to expected results
for QA/QC assurance. 相似文献
4.
Collocation Methods for Weakly Singular Second-kind Volterra Integral Equations with Non-smooth Solution 总被引:2,自引:0,他引:2
Collocation type methods are studied for the numerical solutionof the weakly singular Volterra integral equation of the secondkind:
where the solution (t) is assumedto have the form f(t) = x(t)+r?(t), x and being sufficientlysmooth. The solution is approximated near zero by a linear combinationof powers of t?, and away from zero by the usual polynomialrepresentation. Convergence is proved and many numerical experimentsare carried out with examples from the literature. A comparisonis made with a method of Brunner & Norsett (1981), originallydeveloped for (1) with a smooth solution. Special attentionis paid to the numerical approximation of the so-called momentintegrals which emerge in the collocation scheme. 相似文献
5.
S.G. Schulman K. Abate P.J. Kovi A.C. Capomacchia D. Jackman 《Analytica chimica acta》1973,65(1):59-67
The fluorescences of 6- and 7-aminoquinoline and 6-dimethylaminoquinaldine were studied in media of different acidities, polarities, hydrogen-bonding capabilities and temperatures. The excited state acidities and solvent dependences of the fluorescences of these compounds are typical of aminoquinolines substituted in the homocyclic ring. The acidities of the doubly protonated cations are so great in the lowest excited singlet state, however, that prototropic dissociation in the excited state occurs even in rigid media at 195°K. The lowest triplet state of the singly charged cation of 6-aminoquinoline is found to be nearly degenerate with the lowest excited singlet state of the same molecule. This is attributed to the great charge-transfer component of the S1←S0 transition which is not present in the T1←S0 transition, and the interaction of the S1 state with the polar solvent. 相似文献
6.
7.
Dennis Earl Jackman 《Journal of heterocyclic chemistry》1990,27(4):1053-1057
A blue pigment which sometimes accompanies the manufacture of the triazine herbicide metribuzin ( 5 ) was identified as the novel thiadiazole formazan 10 which arises from the reaction of two impurities 3 and 7 . The latter compound is a keto acid derivative of 2,4-dihydrazinothiadiazole which in turn is an impurity in carbonothioic dihydrazide. Compound 7 has the interesting property of undergoing a facile oxidative decarboxylation in the presence of alcohols to form hydrazonate esters and in the presence of aliphatic amines to form red amidrazone dyes 9 . The N-substituted dyes can be oxidized to ditriazolothiadiazoles 12 . 相似文献
8.
Olga Riba Robert J. Barnes Thomas B. Scott Murray N. Gardner Simon A. Jackman Ian P. Thompson 《Journal of nanoparticle research》2011,13(10):4591-4601
A reactivity study was undertaken to compare and assess the rate of dechlorination of chlorinated aliphatic hydrocarbons (CAHs)
by annealed and non-annealed nanoscale iron particles. The current study aims to resolve the uncertainties in recently published
work studying the effect of the annealing process on the reduction capability of nanoscale Fe particles. Comparison of the
normalized rate constants (m2/h/L) obtained for dechlorination reactions of trichloroethene (TCE) and cis-1,2-dichloroethene (cis-1,2-DCE) indicated that
annealing nanoscale Fe particles increases their reactivity ~30-fold. An electron transfer reaction mechanism for both types
of nanoscale particles was found to be responsible for CAH dechlorination, rather than a reduction reaction by activated H2 on the particle surface (i.e., hydrogenation, hydrogenolysis). Surface analysis of the particulate material using X-ray diffraction
(XRD) and transmission electron microscopy (TEM) together with surface area measurement by Brunauer, Emmett, Teller (BET)
indicate that the vacuum annealing process decreases the surface area and increases crystallinity. BET surface area analysis
recorded a decrease in nanoscale Fe particle surface area from 19.0 to 4.8 m2/g and crystallite dimensions inside the particle increased from 8.7 to 18.2 nm as a result of annealing. 相似文献
9.
Royal B. Jackman 《Experimental Mechanics》1969,9(12):23N-43N
The evolvement of laboratory work during the development of aerospace systems is discussed. Factors affecting laboratory organizations are defined. It is shown that laboratories can be organized in various combinations of technologies, systems or functions. The most effective organization depends on factors such as company products, size and personnel capabilities. 相似文献
10.
Two newly discovered phases on the Pt(100) surface produced by the adsorption of oxygen have been investigated using Rutherford baekscattering (RBS), nuclear microanalysis (NMA), work function changes (Δφ) and LEED. One phase is associated with the oxygensaturated surface (0.63 ± 0.03 monolayers0.81 × 1015 O atoms cm?2), where a very complex LEED pattern is observed; the other is observed at an average coverage of 0.44 ± 0.05 monolayers and gives rise to a (3 × 1) LEED pattern (when observed at room temperature). For both surfaces, RBS measurements indicate large (? 0.025 nm) Pt atom displacements. Also discussed is a new method for preparing the “clean” (1 × 1)-Pt(100) surface without the need for NO adsorption/decomposition. 相似文献