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We examined the contribution of rubberwood to the timber export markets of Malaysia and Thailand. In Malaysia, rubberwood
has grown from 26% of total exported wood products in 1998 to 35% in 2007. A high proportion of furniture products (80%) is
rubberwood, whereas the contribution of rubberwood to other wooden products is less than 20%. Only 10% of sawn timber and
logs is rubberwood. In Thailand, rubberwood contributes to around 60% of total exported wood products, arising from a high
share of not only furniture products (70%) but also other wood products (around 50%) and sawn timber and logs, which have
increased in share from 40% in 1998 to 79% in 2007. We conclude that the high proportion of rubberwood products in the wood
export markets of these two countries is a result of: (1) scarcity of raw wood materials because of strict controls on the
logging of natural forests; and (2) governmental support to rubberwood production, including financial support to rubber planters
and technical assistance to downstream timber processors. 相似文献
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Akira Shigematsu Nobuya Mizoue Kumiko Ide Kakada Khun Muthavy Pheng Shigejiro Yoshida Katsuhisa Kohroki Noriko Sato 《New Forests》2011,42(2):149-162
We estimated the production of rubberwood from 1996 to 2011 in Cambodia. We employed data from interview surveys with three
rubberwood processing companies and statistics from estate rubber plantations and wood retailing companies. The result was
that the end use of rubberwood in Cambodia was the sawntimber products, being exported to Vietnam and China. The yield rate
from rubberwood stumpage into sawn timber was between 11.6 and 14.9%, closely matching the rates of Malaysia and Thailand.
The average production of rubberwood roundwood from 1996 to 2011 was 254,697 m3/year, of which sawn timber as well as residuals in secondary processing was 84,559 and 170,138 m3/year, respectively. Although the timber production of Cambodia has declined sharply due to the strict restriction of natural
forest logging, rubberwood could explain more than 60% of the domestic industrial roundwood production from 2000. We suggest
the necessity of monitoring the expansion of rubber plantations in new rubber producing countries and linking the rubberwood
production with the regional wood resource management. 相似文献
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Tomato plants, two Fe‐efficient cultivars and one Fe‐inefficient cultivar, were grown in treatment combinations of normal and low Fe and K concentrations (Normal Fe, Normal K; Low Fe, Normal K; Low Fe, Low K). Iron‐stressed plants with normal K levels were the first to show elevation of root proton excretion and an enhanced ability to regreen. Roots from the Fe‐efficient cultivars had a marked increase in the rate of CO2 dark fixation that was most prominent with a Normal K, Low Fe. The amount of 14C labeling of root organic acids, particularly malate, citrate, lactate and oxaloacetate increased under Fe‐stress conditions in the Fe‐efficient cultivars; Fe stress with low K resulted in less 14C labeling. A scheme for Fe reduction, uptake and transport is discussed related to CO2 fixation and organic acids (malate, citrate and oxaloacetate.) 1Part of the research done by the senior author while on leave at the Institute for Whole Body Metabolism, Inba, Chiba, Japan. The helpful assistance of Mr. Y. Mabuchi and T. Sakemoto is recognized. 相似文献
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Mikiji Shigematsu Takayuki Kobayashi Hiroyasu Taguchi Mitsuhiko Tanahashi 《Journal of Wood Science》2006,52(2):128-133
The radical coupling reaction leading to the β-0′ quinonemethide intermediate of p-coumaryl alcohol was analyzed by semi-empirical molecular orbital calculation with MOPAC2002. By analyzing the radical monomer
in a one-electron oxidation, the spin density of the unpaired electron at the 4-oxygen was less than half of the values at
the C1, C3, C5, and Cβ positions. By analyzing the transition state during the radical coupling reaction, the activation enthalpy was evaluated
as 9.76 kcal/mol, which corresponds to the activation energies for the propagation of common vinyl polymers. From the analysis
of atomic interactions in the transition state, it was found that the activation enthalpy was largely composed of a high coulombic
repulsion between Cβ of the first monomer and the phenolic oxygen of the second monomer. After passing the transition state, the two radical monomers
formed a metastable quinone-methide intermediate. The optimum conformation of the quinonemethide intermediate was formed from
the meta-stable conformation through a second transition state with a small energy barrier.
Part of this article was presented at the 46th Lignin Symposium, held in Fukuoka, October 31-November 1, 2002 相似文献
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Pythium rot of Chinese cabbage (Brassica rapa L. subsp. pekinensis) caused by Pythium aphanidermatum
Motoaki Tojo Tatsurou Shigematsu Hisataka Morita Yingjie Li Tadashi Matsumoto Satoshi T. Ohki 《Journal of General Plant Pathology》2005,71(5):384-386
Severe rot was found at the base of leaves and stems of Chinese cabbage (Brassica rapa L. subsp. pekinensis) in Ibaraki Prefecture every year in early September from 2002 through 2004. The causal fungus was identified as Pythium aphanidermatum (Edson) Fitzpatrick. This is the first report of P. aphanidermatum on Chinese cabbage. A similar disease of Chinese cabbage caused by P. ultimum Trow var. ultimum is known as Pythium rot. We propose adding P. aphanidermatum as a new pathogen of this disease. 相似文献
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Ryuji Kondo Kotaro Shigematsu Naoki Kawahara Takahiko Okamura Yang Ho Yoon Tomoko Sakami Hisashi Yokoyama Yoshitsugu Koizumi 《Fisheries Science》2012,78(1):123-131
The abundance of sulphate-reducing bacteria (SRB) was investigated in the coastal marine sediments along the coast of Japan
and South Korea. Sediment samples were collected from fish and shellfish farms between 2006 and 2008. As non-fish farming
reference sites, sediments were also collected from highly eutrophic bays, a highly sulphidogenic saline lake, and the deep
sea. A quantitative real-time PCR analysis that targeted the gene coding for a portion of the α-subunit of dissimilatory sulphite
reductase (dsrA) was performed to assess the abundance of the SRB in the sediments. Between 2.8 × 107 and 2.5 × 109 copies of the dsrA gene per gram dry sediment were detected. There was no relationship between dsrA gene copy number and total bacterial count in the sediments, whereas organic matter contents (particulate organic carbon
and nitrogen, ignition loss and chemical oxygen demand) and acid-volatile sulphide contents were significantly correlated
with the dsrA copy number. The data presented demonstrate that organic enrichment of sediment may influence the abundance of SRB communities
in coastal marine sediments and that the cell density of SRB may be used as a biological indicator for assessing pollution
levels in sediments of marine fish farms. 相似文献
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The spin and charge densities in three monolignol radicals were computed using the UB3LYP/6-31G* method of molecular orbital
calculation. As well, the effects of solvents were simulated by using an SCI-PCM model. It was confirmed that an unpaired
electron was localized at C1, C3, C5, C8, and O4 for all monolignol radicals. In solvents, the spin density decreased at O4 with increasing solvent polarity, but increased at C8. The atomic charges at all reactive atoms had a negative value and were obviously strengthened at O4 with increasing solvent polarity. These tendencies support the experimental results for radical coupling reactions of monolignols
in various solvents; that is, that 8-O4′ linkages are produced much more often than 8-8′ linkages in nonpolar solvents. 相似文献