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排序方式: 共有64条查询结果,搜索用时 312 毫秒
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R. H. Filby G. J. Van Berkel A. E. Bragg A. Joubert W. E. Robison C. A. Grimm 《Journal of Radioanalytical and Nuclear Chemistry》1985,91(2):361-368
National Bureau of Standards residual fuel oil Standard Reference Materials, SRM 1619, 1620a, 1634a, and former SRM 1634 were analyzed for 20 trace elements by instrumental neutron activation analysis to determine whether these materials are suitable trace element standards for elements other than the 6 elements certified in SRM 1634a. The SRM 1634a is a suitable standard for Ni, V, Se, Na, Zn, As, Cr, Fe, Ce, Sm and La but Co, Ba, Nd, Cs, Eu, Sc, and Sb appear to be heterogeneously distributed and are probably present in mineral particulates. The SRM 1619 is a convenient standard for V and for low Ni content oils, but SRM 1620a does not appear to be a suitable standard for any trace element investigated.To whom correspondence should be addressed. 相似文献
3.
B. F. Smith R. R. Gibson G. D. Jarvinen T. W. Robison N. C. Schroeder N. D. Stalnaker 《Journal of Radioanalytical and Nuclear Chemistry》1998,234(1-2):225-229
A preconcentration approach to assist in the measurement of low levels of americium and plutonium in waste waters has been
developed based on the concept of using water-soluble metal-binding polymers in combination with ultrafiltration. The method
has been optimized to give over 90% recovery and accountability from actual waste water. 相似文献
4.
V. E. Noshkin W. L. Robison K. M. Wong R. J. Eagle 《Journal of Radioanalytical and Nuclear Chemistry》1998,234(1-2):243-249
There continue to be reports in the literature that suggest a difference in the behavior of239+240Pu and238Pu in some aquatic environments. Plutonium isotopes have been measured in marine samples collected over 3 decades from Enewetak
atoll, one of the sites in the Marshall Islands used by the United States between 1946 and 1958 to test nuclear devices. The
plutonium isotopes originated from a variety of complex sources and could possibly coexist in this environment as different
physical-chemical species. However results indicate little difference in the mobility and biological availability of239+240Pu and238Pu. 相似文献
5.
Preparation and Regioselective Metalation of Bis(trimethylsilyl)methyl‐Substituted Aryl Derivatives
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Veronika Werner Thomas Klatt Masaya Fujii Jenifer Markiewicz Prof. Dr. Yitzhak Apeloig Prof. Dr. Paul Knochel 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(27):8338-8342
A range of bis(trimethylsilyl)methyl‐substituted aryl derivatives was prepared by using a Kumada–Corriu cross‐coupling reaction. The regioselective metalation of the resulting bis(trimethylsilyl)methyl‐substituted aryl derivatives bearing this bulky silyl group allowed the generation of functionalized aromatics. A regioselective switch in the presence or in the absence of the bis(trimethylsilyl)methyl group has been demonstrated. Furthermore, this silyl group was converted into a formyl group or a styryl group, enhancing the scope of application of such bis(trimethylsilyl)methyl‐substituted arenes. 相似文献
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T. F. Hamilton W. L. Robison S. Kehl A. C. Stoker C. L. Conrado 《Journal of Radioanalytical and Nuclear Chemistry》2000,243(2):415-422
The Lawrence Livermore National Laboratory has developed an extensive quality assurance program to provide high quality data and assessments in support of the Marshall Islands Dose Assessment and Radioecology Program. Our quality assurance objectives begin with the premise of providing integrated and cost-effective program support (to meet wide-ranging programmatic needs, scientific peer review, and build public confidence) and continue through from design and implementation of large-scale field programs, sampling and sample preparation, radiometric and chemical analyses, documentation of quality assurance/quality control practices, exposure assessments, and dose/risk assessments until publication. The basic structure of our radioassay quality assurance/quality control program can be divided into four essential elements: (1) sample and data integrity control, (2) instrument validation and calibration, (3) method performance testing, validation, development and documentation, and (4) periodic peer review and on-site assessments. While our quality assurance objectives are tailored towards a single research program and the evaluation of major exposure pathways/critical radionuclides pertinent to the Marshall Islands, we have attempted to develop quality assurance practices that are consistent with proposed criteria designed for laboratory accreditation. 相似文献
8.
Lippow SM Moon TS Basu S Yoon SH Li X Chapman BA Robison K Lipovšek D Prather KL 《Chemistry & biology》2010,17(12):1306-1315
Engineered biosynthetic pathways have the potential to produce high-value molecules from inexpensive feedstocks, but a key limitation is engineering enzymes with high activity and specificity for new reactions. Here, we developed a method for combining structure-based computational protein design with library-based enzyme screening, in which inter-residue correlations favored by the design are encoded into a defined-sequence library. We validated this approach by engineering a glucose 6-oxidase enzyme for use in a proposed pathway to convert D-glucose into D-glucaric acid. The most active variant, identified after only one round of diversification and screening of only 10,000 wells, is approximately 400-fold more active on glucose than is the wild-type enzyme. We anticipate that this strategy will be broadly applicable to the discovery of new enzymes for engineered biological pathways. 相似文献
9.
Arch D. Robison 《BIT Numerical Mathematics》1990,30(1):51-61
We discuss several improvements to an algorithm for computing the rewriting number of a group. Our improvements speed up the computation by a couple of orders of magnitude. With the faster algorithm, we have shown that the rewriting number of the symmetric groupS
5 is 8.Supported by a fellowship from the Shell Oil Company Foundation. 相似文献
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