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991.
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994.
    
A municipal sewer system has been investigated for the sources of a set of semivolatile compounds, such as polychlorinated dibenzo-p-dioxins (PCDD), polychlorinated dibenzofurans (PCDF), polychlorinated biphenyls (PCB), hexachlorobenzene (HCB), 1,1-dichloro-2,2-bis(p-chlorophenyl)-ethene (4,4'-DDE), and chlorinated paraffins (CP), using sewer films as the sampling medium. A cleanup method for these semivolatile compounds in sewer films is described. The project has been undertaken for the differentiation and localization of specific inputs of xenobiotics from defined regions of the city. A unique pattern of PCDD/PCDF found in sewage sludge has led to the search for a specific source within the sewer system, which has finally been localized as a distinct plant. Other organochlorine compounds proved to be significant indicators for industrial and domestic sewers. PCB appeared as an industry correlated parameter, while 4,4'-DDE indicated domestic sewers. Chlorinated paraffins have been detected in the mg/kg range and are markers and indicators for metal-working industries. Finally, the release of CP by the sewage treatment plant, into the nearby river, has been investigated.Dedicated to Professor Dr. Dr. h.c. mult. J. F. K. Huber on the occasion of his 70th birthday  相似文献   
995.
We study ergodic infinite measure preserving transformations T possessing reference sets of finite measure for which the set of densities of the conditional distributions given a first return (or entrance) at time n is precompact in a suitable function space. Assuming regular variation of wandering rates, we establish versions of the Darling-Kac theorem and the arcsine laws for waiting times and for occupation times which apply to transformations with indifferent orbits and to random walks driven by Gibbs-Markov maps. This research was supported by an APART [Austrian programme for advanced research and technology] fellowship of the Austrian Academy of Sciences. Much of this work was done at the Mathematics Department of Imperial College London. I also benefitted from a JRF at the ESI in Vienna.  相似文献   
996.
We introduce and study a Hopf algebra containing the descent algebra as a sub-Hopf-algebra. It has the main algebraic properties of the descent algebra, and more: it is a sub-Hopf-algebra of the direct sum of the symmetric group algebras; it is closed under the corresponding inner product; it is cocommutative, so it is an enveloping algebra; it contains all Lie idempotents of the symmetric group algebras. Moreover, its primitive elements are exactly the Lie elements which lie in the symmetric group algebras.  相似文献   
997.
An efficient synthetic route to 1,6- and 1,7-dibromo-3-aminoisoquinoline was devised. These intermediates served as ideal templates for the preparation of 3-aminoisoquinoline analogues functionalized at C(6) or C(7).  相似文献   
998.
999.
Summary This review serves to highlight the recent examples of combinatoric methodology as applied to the discovery and optimization of enzyme inhibitors. Early research efforts focused on the identification of polypeptides from libraries as inhibitors of proteases. As solution- and solid-phase chemistries gain in sophistication, libraries containing less peptidic structural motifs have been created. A recurring design stratagem relies on the synthesis of libraries incorporating pharmacophores with known affinity for the target enzyme. Screening of these structure-based libraries has led to the discovery of small-molecule inhibitors of both proteolytic and non-proteolytic enzymes alike. Two tables are provided listing the enzyme targeted libraries through 1996. A name, generic structure and size is given for each library citation, accompanied by the enzyme screen and the structure and potency of the most active library member.  相似文献   
1000.
We first show that increasing trees are in bijection with set compositions, extending simultaneously a recent result on trees due to Tonks and a classical result on increasing binary trees. We then consider algebraic structures on the linear span of set compositions (the twisted descent algebra). Among others, a number of enveloping algebra structures are introduced and studied in detail. For example, it is shown that the linear span of trees carries an enveloping algebra structure and embeds as such in an enveloping algebra of increasing trees. All our constructions arise naturally from the general theory of twisted Hopf algebras.  相似文献   
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