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Search Results: 1 - 10 of 8033 matches for " Ahmad Pervez "
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Remote Sensing Data Application to Monitor Snow Cover Variation and Hydrological Regime in a Poorly Gauged River Catchment—Northern Pakistan  [PDF]
Samreen Abdul Hakeem, Muhammad Bilal, Arshid Pervez, Adnan Ahmad Tahir
International Journal of Geosciences (IJG) , 2014, DOI: 10.4236/ijg.2014.51005

Snow- and glacier-nourished river basins located in the Himalaya-Karakoram-Hindukush (HKH) ranges supply a significant amount of discharge in River Indus upstream Tarbela Dam. It is, hence, important to comprehend the cryosphere variation and its relationship to the stream flow in these high-altitude river catchments. The MODIS remotely sensed database of snow products was chosen to examine the average annual snow and glacier cover (cryosphere) variations in the Shigar River basin (poorly gauged mountainous sub-catchment of the Indus River). Hydrological regime in the area was investigated through monthly database of observed stream fluxes and climate variables (precipitation and mean temperature) for the Shigar River catchment. Analysis indicated the usefulness of remote sensing techniques for estimation of the snow cover variation in the poorly or un-gauged high-elevation catchments of the HKH zone. Results also showed that Shigar River discharge was influenced mainly by the seasonal and annual snow cover area (SCA) variation and the temperature seasonality. Moreover, it is important to uncover such inter-relationship of stream flow, climate variables and snow cover in the poorly gauged high-altitude catchments of Karakoram region for better water resource management and accurate flood hazards predictions at Tarbela.

昆虫学报 , 2013,
Abstract: 在室内研究了不同环境变量(如食物、温度、光周期和不同光波长)下银胶菊杂草PartheniumhysterophorusL.的食叶昆虫和生物防治因子银胶菊叶甲ZygogrammabicolorataPallister的生命表。不同发育阶段的该种叶甲取食银胶菊不同部位时,取食花的甲虫死亡率指标Kappa值最低,其次是取食叶片和茎;而取食花时甲虫世代存活率最高。温度显著影响主要发育阶段该种叶甲的死亡率和存活率。27℃下饲养的未成熟期甲虫的Kappa值最低,其次是30,25,20和35℃。世代存活和存活率表现相同的趋势。不同光周期显著影响死亡率,在14L∶10D(长日照)下世代存活最好,其次是12L∶12D(昼夜相等),10L∶14D(短日照),24L∶0D(连续光照)和0L∶24D(连续黑暗)。甲虫对不同波长光的反应上,在白光(广谱)下Kappa值最低,世代存活率最高,其次是黄光(λ≈570nm)、蓝光(λ≈475nm)和红光(λ≈650nm)。卵的死亡率最高。不同发育阶段的甲虫在27℃长日照白光下用银胶菊花饲养最佳。死亡率趋势具有严格和显著的阶段特异性,表现出内在的存活效应,与研究的因素无关。
Canopy Temperature: A Potential Technique for Evaluating Genetic Response to Drought in Crop Plants
R. Ahmad,N. Ahmad,M. A. Pervez
Pakistan Journal of Biological Sciences , 1998,
Abstract: Remote sensing of crop water stress using infrared radiation thermometers is one of the several important remote sensing applications. Remotely-sensed infrared canopy temperatures provide an efficient method for rapid, nondestructive monitoring of whole plant response to water stress. A logical extension of this technology is the use of canopy temperatures in screening crop genotypes for drought resistance. The potntial of using canopy temperatures in evaluating the genotypic response to drought is reviewed in this paper.
The influence of age on reproductive performance of the predatory ladybird beetle, Propylea dissecta
Ahmad Pervez,Omkar,Aaron S. Richmond
Journal of Insect Science , 2004,
Abstract: The influence of age on reproductive performance of an aphidophagous ladybird beetle, Propylea dissecta was examined using male and female beetles of varying ages (1-30 days) after a single mating stimulus. All the intermediate (10 to 20 days old) and old (30 days old) age females mated with all intermediate and old age males, while only a fraction (0.29%) of younger females, 1 to 5 days old, mated with males of similar or older age. The willingness to mate was male age dependent. It increased sigmoidally with increase in adult age. Adult males were more willing to mate with females irrespective of age. Mating duration was longest amongst older adults (30 day-old males and 20 day-old females). Male age did not contribute to shaping the fecundity of the female ladybird. Fecundity was female age dependent and it increased with age up to 20 days and thereafter decreased. 20 day-old females were most fecund producing 867 eggs after a single mating. Progeny production was male age dependent and eggs sired by 20-30 day-old males had significantly higher viability than those sired by younger males. Prolonged mating increased fecundity and egg viability. The results reveal that males of intermediate age were better mates. This information may improve our understanding of the effect of aging on reproduction in ladybirds and may help mass-multiplication of the ladybird beetles using adults of optimal age.
Humayun Pervez,Maqbool Ahmad,Muhammad Yaqub,M. Nawaz Tahir
Acta Crystallographica Section E , 2010, DOI: 10.1107/s1600536810023263
Abstract: The title compound, C18H18N2O3, is the product of the heterocyclic ring cleavage at position 2 of 1-propionylisatin. Two centrosymmetric cyclic motifs, viz. R22(14) and R22(18), are formed by N—H...O hydrogen bonds with the propanamide and aminophenyl units, respectively, as the N—H donors. These motifs combine into two C22(8) chain motifs parallel to the b axis. The chain structure is stabilized by C—H...π interactions between the benzene rings, where C—H is from the phenyl ring of the cleaved part of 1-propionylisatin.
Humayun Pervez,Muhammad Yaqub,Maqbool Ahmad,M. Nawaz Tahir
Acta Crystallographica Section E , 2010, DOI: 10.1107/s1600536810022580
Abstract: In the title compound, C16H9F4N3O2, the dihedral angle between the aromatic ring systems is 4.10 (14)° and a bifurcated intramolecular N—H...(O,F) hydrogen bond generates an S(6) ring for the O-atom acceptor and an S(5) ring for the F-atom acceptor. A short C—H...O conact also occurs. In the crystal, molecules are linked by C—H...O interactions.
Effect of Different Sources of Nitrogen on Chemical Characters of Guava (Psidium guajava L.)
F.M. Tahir,M.A. Pervez,R. Ahmad
Pakistan Journal of Biological Sciences , 1998,
Abstract: Present studies were carried out to determine the effect of different nitrogen sources on various chemical characters of guava to improve its quality. Two sources (urea and ammonium nitrate) of nitrogen each with two doses (300 and 600 gm) were applied in split doses before flowering and after fruit setting. It was observed that 600 g N per tree from urea proved best for quality improvement followed by ammonium nitrate. The combined application of urea and Ammonium nitrate (300 + 300 g) was found better than their individual effects with the same dozes.
Effect of Growth Regulators on Rooting Performance of Stem Cuttings in Guava (Psidum guajava L.)
F.M. Tahir,M.A. Pervez,R. Ahmad
Pakistan Journal of Biological Sciences , 1998,
Abstract: Potential of using Indole Butyric Acid (IBA) and paclobutrozol (PBZ) for rooting in stem cuttings of guava (Psidum guajava L.) was evaluated in a field study during the year 1995-1996. Two concentrations (500 and 750 ppm) each of IBA and PBZ were applied to three i.e. hard wood, semi-hard wood and softwood types of guava cuttings. Hard wood cuttings and IBA @ 500 ppm performed well with respect to various root and shoot developmental characteristics followed by the IBA @ 750 ppm.
Scientific Approach to Enhance the Income from Guava Orchards
M.A. Pervez,Faqir Muhammad,Manzoor Ahmad
Pakistan Journal of Biological Sciences , 1999,
Abstract: These studies were carried out to find the effect of deblossoming of summer crop on the succeeding winter crop. It has been observed that deblossoming at full bloom stage showed promising results to increase the number of flowers, fruit set percentage, size, weight and yield of fruit and to decrease the flower and fruit drop. Time taken for flower bud opening and fruit maturity was also reduced thus an early winter crop was obtained. Deblossoming at unopened bud stage and fruit thinning at different intervals after fruit setting also showed better results than control. Fruit thinning at later stages after fruit setting, had decreasing affect on yield.
Optimum Conditions for the Synthesis of Dimethylol Urea Textile Fixer
Fiyyaz Ahmad Chughtai,Khalid Pervez Bhatti,Muhammad Zuber,Sofia Nosheen
Journal of Applied Sciences , 2003,
Abstract: Being a major textile exporting country, Pakistan exports textile products and earns a lot of money. On the other hand it spends huge amount of foreign exchange on importing textile auxiliaries like dye intermediates, dye fixing agents, fluorescent brighteners etc. formaldehyde precondensates with amino compounds and this forms an important class of polymers like Phenol-formaldehyde, Melamine-formaldehyde etc. used largely and effectively in textile industry as dye fixing agents. At present Dimethoylol Urea (DMU) is one of the main chemical is being imported from Germany and United States of America. Present project is an attempt to synthesize DMU locally on laboratory scale. Results revealed that formalin on treatment with urea at pH 7.5 synthesized low molecular weight precondensate (DMU) that was miscible with water. Optimum time period for the completion of reaction was found to be 2 hrs. Moreover it was determined that one mole of urea required 1.5 to 1.6 moles of formalin (formaldehyde) to react completely. The results revealed that DMU precodensate is the better for rayon as compared to cotton.
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