排序方式: 共有36条查询结果,搜索用时 15 毫秒
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The paper deals with general limnology, phytoplankton production and trophic status of a Himalayan lake of Kashmir. The primary production as measured by in situ 14C istope technique ranged from 36 to 906 mgC.m–2 d–1 with characteristic seasonal variation. The photosynthetic efficiency was from 0.02 to 0.48% during the same period. The yearly (1975–1976) production was estimated at 134 gC.m–2 m–2, which shows that the lake has not yet reached a high level of eutrophication. The waterbody has been classified as mesotrophic.Formed part of thesis for which Ph. D. was awarded to MAK by Kashmir University, India 相似文献
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Dayton PA Zhao S Bloch SH Schumann P Penrose K Matsunaga TO Zutshi R Doinikov A Ferrara KW 《Molecular imaging》2006,5(3):160-174
Lipid-coated perfluorocarbon nanodroplets are submicrometer-diameter liquid-filled droplets with proposed applications in molecularly targeted therapeutics and ultrasound (US) imaging. Ultrasonic molecular imaging is unique in that the optimal application of these agents depends not only on the surface chemistry, but also on the applied US field, which can increase receptor-ligand binding and membrane fusion. Theory and experiments are combined to demonstrate the displacement of perfluorocarbon nanoparticles in the direction of US propagation, where a traveling US wave with a peak pressure on the order of megapascals and frequency in the megahertz range produces a particle translational velocity that is proportional to acoustic intensity and increases with increasing center frequency. Within a vessel with a diameter on the order of hundreds of micrometers or larger, particle velocity on the order of hundreds of micrometers per second is produced and the dominant mechanism for droplet displacement is shown to be bulk fluid streaming. A model for radiation force displacement of particles is developed and demonstrates that effective particle displacement should be feasible in the microvasculature. In a flowing system, acoustic manipulation of targeted droplets increases droplet retention. Additionally, we demonstrate the feasibility of US-enhanced particle internalization and therapeutic delivery. 相似文献
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Pesticides are known to affect the testis in fishes and cause cytomorphological changes or gross physiological alterations due to changes in its histology, retard gonadotrophic secretions thereby causing regression of the gonads. Light and ultrastructural studies were made on control and fenthion treated testis, interstitial gland and sperms of G. giuris during spawning phase after exposing them to different sub-lethal concentrations (0.05, 0.25 and 0.5 ppm) fenthion for a short-term period (24, 48, 72 and 96 hr). The results indicated extensive cytotoxic damages in the testis including atrophy of testis, reduction in lipoidal material in the interstitial cell and degeneration of sperms. The alteration in histology of testis, interstitial cell and sperms progressively increased with the increase in the sub-lethal concentration of pesticides. 相似文献
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R C Bucknall J Dixon A St E N Glick J Woodland D W Zutshi 《BMJ (Clinical research ed.)》1975,1(5958):600-602
Four patients with rheumatoid arthritis (R.A.) developed myasthenia gravis after taking penicillamine. In one patient withdrawal of the drug was followed by spontaneous remission of the myasthenia, and in two the dose of anticholinesterase was subsequently reduced. In the fourth patient continuing penicillamine treatment was associated with increasingly severe myasthenic features, but on withdrawal of the drug these resolved. As myasthenia gravis rarely complicates R.A. its onset in these patients shortly after the start of penicillamine treatment suggested that penicillamine may have precipitated this condition. 相似文献
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Kumawat Surbhi Aggarwal Bharti Rana Nitika Mandlik Rushil Mehra Akrity Shivaraj S. M. Sonah Humira Deshmukh Rupesh 《Journal of plant biochemistry and biotechnology.》2021,30(4):930-942
Journal of Plant Biochemistry and Biotechnology - Aquaporins (AQPs), pore-forming proteins, are known to involve in the transport of water and many other small solutes, and play a diverse role in... 相似文献
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A novel strategy was used to irreversibly inhibit HIV-1 protease. The inhibitor was designed to form a disulfide bond with Cys95, present at the dimerization interface of HIV-1 protease. The inhibitor was shown to be active against HIV-1 protease with K(inact) = 3.7 microM and V(inact) = 0.012 min(-1). 相似文献
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Sunaina Zutshi Meenakshi Choudhary Naveen Bharat Malik Zainul Abdin Tasneem Fatma 《Journal of phycology》2008,44(4):889-896
Lead (Pb) is a heavy metal and a potentially hazardous environmental pollutant. In this study, the potential of lead to induce oxidative stress in biological systems was assessed using the cyanobacterium Hapalosiphon fontinalis‐339 as model test organism. The impact of lead toxicity on the cellular antioxidant system and the biochemical modulations that result in generation of antioxidant defense responses were also studied. To determine the effect of Pb toxicity, the test organism was grown in the presence of various concentrations (0.05, 0.10, 0.20, 0.40, 0.80, 1.0, 1.20, and 1.25 mg · L?1) of exogenous lead chloride (PbCl2), and its effects on growth were observed in terms of the change in chl content. There was a significant increase in metal uptake by the alga with a concomitant decrease in growth. Lead stress appeared to significantly up‐regulate the levels of stress‐related antioxidant enzymes—such as superoxide dismutase (SOD), ascorbate peroxidase (APX), and glutathione reductase (GR)—while a decrease in catalase (CAT) levels was observed. In addition, the levels of nonenzymatic antioxidants, oxidized and total glutathione, were changed. Our results suggest the existence of a potent antioxidant defense machinery in H. fontinalis‐339 and this organism can be employed to monitor lead toxicity in the environment. 相似文献
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Two lakes in the lower Siwalik Himalayas, five in the Kashmir valley and two situated in the high mountains of the Kashmir Himalayas were investigated for their physico-chemical and biological features. The lakes, differing significantly in their morphology and in thermal behaviour, rank from the subtropical monomictic to the dimictic type. The lakes at high altitudes (> 3000 m) have very low electric conductivity which increases with the decrease in altitude. The most dominant ions in water are calcium and bicarbonate. The macrophytic vegetation of the lakes does not show any definite relationship either with altitude or with physico-chemical milieu. In the lakes with low fertility the phytoplankton is dominated by diatoms and Chlorophyceae but in eutrophic lakes Cyanophyceae predominate. The zooplankton population of the lakes is mainly comprised of rotifera. On the basis of general limnological features and the rates of phytoplankton production most of the lakes may be categorized either as eutrophic or in the process of rapid evolution. Only one lake is oligotrophic. 相似文献