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991.
几种蒸散模型在玉米农田蒸散量计算中的应用比较 总被引:3,自引:1,他引:2
模拟蒸散的物理过程,计算农田蒸散量是进行生态系统水资源评价和管理的重要手段,同时也是气象部门进行土壤湿度预报的首要条件.本研究以玉米农田为研究对象,基于涡度相关法观测的蒸散实测资料,比较分析了基于常规气象数据的蒸散模型(Hargreaves法、Priestlev-Taylor法、FAO-Penman-Monteith法)和基于气象梯度数据的蒸散模型(波文比法、梯度法、生态系统过程模型模拟)的模拟精度.结果表明:①Hargreaves法、Priestley-Taylor法和FAO-Penman-Monteith法日蒸散的模拟结果较为一致,总体上高估20%~26%,其中Priestley-Taylor法模拟结果最优;②生态系统过程模型模拟的农田日蒸散精度较高,但模型中涉及的物理过程和参数较多,在实际应用中难于获取;③波文比法在波文比小于0.4且仪器精度较高时可以得到较准确的估算值.研究同时还指出,仪器的安装高度及高差设计对梯度法估算蒸散十分重要. 相似文献
992.
Suvidya H. Ranade Ashraf Hossani D. N. Deobagkar D. D. Deobagkar B. A. Chopade Pramod S. Khandekar 《Indian journal of clinical biochemistry : IJCB》2009,24(2):142-149
We report complete sequences of 2 genes of S.flexneri 1a an Indian isolate for the first time. Shigella is causative agent
of shigellosis or bacillary dysentery. Genomic library was constructed by shotgun approach. Sequencing was carried out using
Big Dye terminator chemistry using ABI 3730 48 capillary DNA analyzer. 170 recombinants were subjected to nucleotide sequencing.
Sequence data was analyzed, of these 2 clones showed presence of complete genes out of the total clones sequenced. Annotations
were done using various bioinformatics tools. Gene Sfo676 on contig SF21B11, 513 bp long codes for a protein 170 aa long with
molecular weight of 18836.5 daltons. The protein is 99 % identical to S. flexneri 2a 301 and not with any other strain of
Shigella. It has 7 different sites for phosphorylation, myristoylation and glycosylation. Predicted cellular localization
is cytoplasmic membrane. SF0368 is another full-length gene SF0368 on contig SF69C1 is a 312 nucleotide long. It is 103 aa
long with molecular weight 11394.0 daltons. Protein is 100% identical to S. flexneri 2a 301 and 99% with S. sonnei strain
046. The gene shows difference when compared with S.sonnei in mono and dinucleotide frequency as well as amino acid composition. 相似文献
993.
浙江省高校学报现状、问题及发展对策 总被引:2,自引:0,他引:2
高校学报是我国期刊的重要组成部分,其中的自然科学类学报是我国科技创新和建设创新型国家的主要媒体之一.本文对浙江省50家高校学报的办刊情况等方面进行了调查,分析得出高校学报由于受传统办刊观念的影响,随着我国高等教育改革的不断深化,同样面临着巨大的挑战和机遇.针对目前高校学报普遍存在着办刊思想保守、脱离市场、缺少经营意识等问题,并由此提出了进一步提高浙江省高校学报办刊质量的对策和建议. 相似文献
994.
We exploited the viscoelasticity of biocompatible dilute polymeric solutions, namely, dilute poly(ethylene oxide) solutions, to significantly enhance mixing in microfluidic devices at a very small Reynolds number, i.e., Re≈0.023, but large Peclet and elasticity numbers. With an abrupt contraction microgeometry (8:1 contraction ratio), two different dilute poly(ethylene oxide) solutions were successfully mixed with a short flow length at a relatively fast mixing time of <10 μs. Microparticle image velocimetry was employed in our investigations to characterize the flow fields. The increase in velocity fluctuation with an increase in flow rate and Deborah number indicates the increase in viscoelastic flow instability. Mixing efficiency was characterized by fluorescent concentration measurements. Our results showed that enhanced mixing can be achieved through viscoelastic flow instability under situations where molecular-diffusion and inertia effects are negligible. This approach bypasses the laminar flow limitation, usually associated with a low Reynolds number, which is not conducive to mixing. 相似文献
995.
996.
R. B. Bhogade A. N. Suryakar N. G. Joshi R. Y. Patil 《Indian journal of clinical biochemistry : IJCB》2008,23(3):233-237
Hemodialysis represents a chronic stress status for its recipients. Many hypotheses state that this may be associated with
oxidative stress. Thus, there may be deficiency of antioxidants like erythrocytic superoxide dismutase, catalase, vitamin
E or increased generation of free radicals like superoxide anions. A study was carried out to investigate oxidant and antioxidant
status in chronic renal failure patients undergoing hemodialysis and effect of vitamin E supplementation on these two status.
Blood samples were collected from patients before and after hemodialysis and from controls. The samples were analyzed for
quantitation of MDA as index of lipid peroxide, nitric oxide, vitamin E, vitamin C and enzymatic antioxidants namely erythrocyte
SOD and catalase. As compared to controls, the levels of serum MDA were significantly increased and activities of erythrocyte
SOD and catalase, levels of serum nitric oxide, serum vitamin E and plasma vitamin C were significantly decreased both before
and after hemodialysis. The efficiency of vitamin E therapy in hemodialysis patients was assessed by re-evaluating oxidant
and antioxidant status of same patients after supplementation of vitamin E. Vitamin E supplementation caused decrease in serum
MDA and increase in levels of serum nitric oxide, vitamin E, vitamin C and activities of erythrocytic SOD and catalase. Our
results suggest the presence of oxidative stress and the possible preventive role of vitamin E therapy in hemodialysis patients. 相似文献
997.
Benedicta D’Souza Vivian D’Souza S. Sowmya G. Seema C. N. Hemalatha M. Anu G. Sajana 《Indian journal of clinical biochemistry : IJCB》2008,23(3):218-222
The study was conducted to find out the extent of lipid peroxidation and antioxidant status in ischemic stroke patients (ISPs)
with and without diabetes. Malondialdehyde (MDA) was studied as a marker of lipid peroxidation. Glutathione (GSH), uric acid
and ceruloplasmin were estimated to study the antioxidant potential of ISPs. Significantly higher levels of MDA were found
in both the groups of ISPs and the increase in MDA was more in ISPs without diabetes. GSH levels were decreased significantly
in both the groups of ISPs and maximum decline was found in ISPs with diabetes. Uric acid levels were significantly increased
in both the groups of ISPs. Ceruloplasmin levels were increased significantly in ISPs without diabetes, whereas its levels
were slightly decreased in ISPs with diabetes. A negative correlation was found between MDA and the antioxidants GSH, uric
acid and ceruloplasmin in ISPs with diabetes. This study suggests that there is an association between ischemic stroke and
increased oxidative stress and the antioxidant potential is impaired in both the groups of ISPs with and without diabetes. 相似文献
998.
Sunil Chandy M. N. Sadananda Adiga Girija Ramaswamy C. Ramachandra Lakshmi Krishnamoorthy 《Indian journal of clinical biochemistry : IJCB》2008,23(3):258-261
Folate and cobalamin (Vitamin B12) are two essential micronutrients involved in one-carbon metabolism, which affects heart disease, neural tube defects and
cancer. Methylenetetrahydrofolate reductase, the key enzyme involved in one carbon metabolism produces methyl tetrahydrofolate
from methylene tetrahydrofolate, which in turn donates methyl group to homocysteine to generate methionine. There exist two
common low function polymorphic variants of the methylenetetrahydrofolate reductase gene involving nucleotides 677 C→T and
1298 A→C, which are associated with hyperhomocysteinemia. These polymorphisms are also linked with increased risk for certain
cancers such as breast cancer and at the same time providing a protective effect on colorectal cancer. In this case control
study, we have evaluated levels of folic acid, vitamin B12 and homocysteine in patients with colorectal cancer. Folate and homocysteine levels did not differ significantly between
the two groups; however an increasing trend was noticed with increase in homocysteine levels. Vitamin B12 levels were increased in cases compared to control group. 相似文献
999.
A. Ravi Raja G. N. Vishal Babu Geraldine Menezes T. Venkatesh 《Indian journal of clinical biochemistry : IJCB》2008,23(2):200-203
Awareness about the toxic effects of non-essential metals is still lacking in developing countries. Lead is one among them,
which ranks second in the Agency for Toxic Substances and Disease Registry’ s top 20 lists of toxic metals. Some of the herbal
medicines prepared from certain roots and leaves are known to contain this toxic metal at alarming levels. We have a case
of a person who suffered from the toxic effects of lead such as vomiting and colicky abdominal pain after consuming a herbal
remedy for Jaundice treatment. This went unrecognized initially because of the presence of multiple problems like Malaria
and Renal calculi. Lead poisoning as causative factor for anemia, vomiting and colic were confirmed only when blood lead concentration
was estimated. A combination of chelation therapy and nutritional supplementation was found to be useful in reducing the body
lead burden. 相似文献
1000.
K. Devika Rani N. Suneetha Shruti Mohanty Pragna Rao 《Indian journal of clinical biochemistry : IJCB》2008,23(2):150-153
This study is conducted in chronic alcoholics to assess the association of an Individual’s level of serum homocysteine with
the success of achieving alcohol deaddiction in the patient. The patients’ nutrition status is also assessed. 50 chronic alcoholics
admitted to a deaddiction center were inducted into the study. Patients underwent an 8 weeks holistic program to promote rehabilitation
from alcoholism. All the patients were addicted to alcohol for 8 – 10 years. Of the 50 patients enrolled, 39 of them completed
the 8 weeks program including complete abstinence from alcohol during this period. Fasting blood samples were collected on
admission and again after 8 weeks of alcohol abstinence for analyses of serum homocysteine and serum prealbumin, transferrin,
total proteins and albumin, gammaglutamyl transferase (GGT) and alanine transaminase (ALT). Of the 50 patients enrolled in
the study, 39 completed the 8 weeks rehabilitation program. 11 patients discontinued within 2 weeks of admission. During the
8 weeks of complete alcohol abstinence, patients were given a balanced diet and multivitamin supplements. A significant improvement
in their nutritional status was noted by the elevation of serum levels of prealbumin, transferrin, total proteins and albumin.
Serum homocysteine levels decreased significantly (p<0.002) to normal levels from previous hyperhomocytenemia. This was accompanied
by decrease in serum GGT and ALT levels indicating improved liver functions. Serum estimation of homocysteine in chronic alcoholics
is important to assess whether the patient will have a successful rehabilitation. Normal homocysteine levels are achieved
after dietary changes and abstinence from alcohol. Timely correction of hyperhomocysteinemia also provides successful rehabilitation. 相似文献