玩转线条

自由蜿蜒的线条不经意间触碰了设计师的灵感,从此一发不可收拾。烛台、凳子、置物篮……线条的魅力正悄然无声地蔓延于生活的每一个角落,尽显艺术美感。     

魅力线条

线条可以简单明了,也可以弯曲复杂。不管怎样,千万别小瞧它的吸引力。     

Importance of Selecting a Quality Demolition Contractor

With the Environmental Protection Agency's recent passing of the Mercury and Air Toxics Standard and the decreasing price of natural gas, coal-fired power plants in America are being forced to shut down at an alarming rate.     

Effect of drought and irrigation on the fate of nitrogen applied to cut permanent grass swards in lysimeters: Leaching losses

Nitrogen losses were measured in water draining from cut permanent grass swards growing in monolith lysimeters containing clay loam (Salop series) or silt loam (Bromyard series) soils. The swards were cut at 6-week intervals during the summer and were fertilised with calcium nitrate at rates of 0 and 400 kg N ha^?1 in each of five successive years (1977–81); in the first year the fertiliser was labelled with ¹⁵N. Four differing rainfall regimes were imposed from spring to autumn in each year. Mean annual losses of nitrogen by leaching from unfertilised swards were 3.8 kg N ha^?1 with mean nitrate-N concentrations in the water of about 1 mg N litre^?1. In fertilised lysimeters where rainfall distribution was that of the long-term average the mean annual total nitrogen losses were 41 kg N ha^?1 in the Salop soil and 15 kg N ha^?1 for the Bromyard soil; mean nitrate-N concentrations were 11.6 mg N litre^?1 and 5.1 mg N litre^?1, respectively. Losses of nitrogen and nitrate concentrations were similar to these quantities when irrigation increased the rainfall total to 120% of average. Where a drought was imposed for 2 weeks before and after each cut, mean nitrate-N concentrations increased to 20.3 mg N litre^?1 on Salop soil and 13.1 mg N litre^?1 on Bromyard soils; total annual nitrogen losses were 74 kg N ha and 33 kg N ha^?1, respectively. The largest losses were recorded when the drought period extended for four weeks before each cut and mean nitrate-N concentrations increases to 28.8 mg N litre^?1 on Salop soil and 34 mg N litre^?1 on Bromyard soil, with total annual nitrogen losses of 104 kg N ha^?1 and 109 kg N ha^?1, respectively. Losses of nitrogen derived from the fertiliser labelled with ¹⁵N were 7.3–8.4% of that applied in the Salop soil (29–33 kg N ha^?1), with little effect by the differing rainfall distributions. On the Bromyard soil, losses were 3.7% (14 kg N ha^?1) of the applied fertiliser in lysimeters not subjected to droughts. When the period of the drought extended before and after each cut, losses were 8.2% (32 kg N ha^?1) and increased to 17.9% (70 kg N ha^?1) when the drought period occurred entirely before each cut. Fertiliser nitrogen contributed 48–69% of the total nitrogen in drainage water from both soils in the first year.     

Expression of NGF/proNGF and Their Receptors TrkA,p75NTR and Sortilin in Melanoma

There is increasing evidence that nerve growth factor (NGF) and its receptors, the neurotrophic receptor tyrosine kinase 1 (NTRK1/TrkA), the common neurotrophin receptor (NGFR/p75^NTR) and the membrane receptor sortilin, participate in cancer growth. In melanoma, there have been some reports suggesting that NGF, TrkA and p75^NTR are dysregulated, but the expression of the NGF precursor (proNGF) and its membrane receptor sortilin is unknown. In this study, we investigated the expression of NGF, proNGF, TrkA, p75^NTR and sortilin by immunohistochemistry in a series of human tissue samples (n = 100), including non-cancerous nevi (n = 20), primary melanomas (n = 40), lymph node metastases (n = 20) and distant metastases (n = 20). Immunostaining was digitally quantified and revealed NGF and proNGF were expressed in all nevi and primary melanomas, and that the level of expression decreased from primary tumors to melanoma metastases (p = 0.0179 and p < 0.0001, respectively). Interestingly, TrkA protein expression was high in nevi and thin primary tumors but was strongly downregulated in thick primary tumors (p < 0.0001) and metastases (p < 0.0001). While p75^NTR and sortilin were both expressed in most nevi and melanomas, there was no significant difference in expression between them. Together, these results pointed to a downregulation of NGF/ProNGF and TrkA in melanoma, and thus did not provide evidence to support the use of anti-proNGF/NGF or anti-TrkA therapies in advanced and metastatic forms of melanoma.     

Emission of nitrous oxide to the atmosphere from direct-drilled and ploughed clay soils

The emission of nitrous oxide to the atmosphere was measured for 2 years (1977-79) from two clay soils (Denchworth and Lawford series) that had either been directdrilled or ploughed. On almost all sampling occasions the emission from directdrilled plots exceeded that from the ploughed plots by factors ranging up to 15-fold. Rates of nitrous oxide loss reached peaks of 2.5-3.0 mg N m-² h-¹ (equivalent to 0.6-0.7 kg N ha-¹ day-¹) from the direct-drilled plots on the Denchworth soil. Emissions of nitrous oxide from the Lawford soil were only 10-20% of those from the Denchworth soil. The total amount of nitrous oxide-N lost during each year from the Denchworth soil was estimated to be 5.4-8.6 kg N ha-¹ from the direct-drilled plots and 0.9-5.6 kg N ha-¹ from the ploughed plots.