Tuyển tập các báo cáo nghiên cứu về y học được đăng trên tạp chí y học Wertheim cung cấp cho các bạn kiến thức về ngành y đề tài: Construction of an Yucatec Maya soil classification and comparison with the WRB framework...
Soils are aggregates of mineral particles, and together with air and/or water
in the void spaces, they form three-phase systems. A large portion of the
earth’s surface is covered by soils, and they are widely used as construction
and foundation materials. Soil mechanics is the branch of engineering that
deals with the engineering properties of soils and their behavior under
Standard Practice for classification of soils and soil-aggregate mixtures for highway construction purposes practice covers a procedure for classifying mineral and organomineral soils into seven groups based on laboratory determination of particle-size distribution, liquid limit, an plasticity index. It may be used when precise engineering classification is required, especially for highway construction purposes. Evaluation of soils within each group is made bymeans of a group index, which is a value calculated from an empirical formula.
Phẩu diện đất là một mặt phẵng (hố đất) được đào thẵng góc từ mặt đất cho đến tầng đá mẹ / mẫu chất Có những tầng đất (soil horizon) khác nhau… Tầng chẩn đóan (diagnostic horizon) Cơ sở nghiên cứu về đất : phân loại đất (soil classification), bản đồ đất (soil map), phân vùng quy hoạch (planning), sử dụng cải tạo.
A framework for international classification, correlation and communication
International Union of Soil Sciences
Cover photograph: Ferralsol (Ghana), Cryosol (Russian Federation), Solonetz (Hungary), Podzol (Austria), Phaeozem (United States of America), Lixisol (United Republic of Tanzania), Luvisol (Hungary). Compiled by Erika Micheli.
Copies of FAO publications can be requested from: SALES AND MARKETING GROUP Information Division Food and Agriculture Organization of the United Nations Viale delle Terme di Caracalla 00100 Rome, Italy E-mail: publications-sales@fao.
Human activities are affecting the global environment in myriad
ways, with numerous direct and indirect effects on ecosystems.
The climate and atmospheric composition of Earth are changing
rapidly. Humans have directly modified half of the ice-free terrestrial
surface and use 40% of terrestrial production. Our actions are
causing the sixth major extinction event in the history of life on
Earth and are radically modifying the interactions among forests,
fields, streams, and oceans.
Over the past 25 years the discipline of ecotoxicology has undergone two
major developments. Firstly, new assays have been developed, deploying
organisms that bear added relevance to the specific environment under
investigation. Several new procedures assess the effects on organisms after
exposure to environmental samples rather than to spiked water or sediment
samples. Also noteworthy is the considerable attention given to effects of
chronic exposure to low levels of contaminants.
Both a classified content and unstructured data view are valid and necessary. Organizational principles are
the domain of librarians creating classifications and ontologies including the semantic web versus machine
learning approaches to self-organize content. However, with large quantities of information, users are not
just unwilling to classify, but are in fact unable to do it. Special skills are required to construct useful
classifications. The first impulse we and others have felt is to just wish away the usefulness of metadata and