411 resultados para 1366


Relevância:

10.00% 10.00%

Publicador:

Resumo:

带障碍物圆管内爆燃的沿程峰值超压和火焰传播速度值是关系到安全生产的重要数据.本文在一氧化碳爆燃实验的基础上,提出了多级分区模型来计算沿程峰值超压,模型将带障碍物管看成由障碍物隔开的首尾相接的一系列的泄爆腔体.基于数据分析,得到了利用一氧化碳氧化反应当量比,膨胀比,开口面积比等已知参数来计算沿程峰值超压的经验公式,研究发现沿程峰值超压与爆燃过程中的气流湍流因子具有近似线性关系,提出了火焰传播速度的经验公式

Relevância:

10.00% 10.00%

Publicador:

Resumo:

IEECAS SKLLQG

Relevância:

10.00% 10.00%

Publicador:

Resumo:

A method for the determination of Au, Pt and Pd in geological samples is described. Au, Pt and Pd can be separated and concentrated quantitatively by C-410 anion-exchange resin in the condition of 1.5 mol/L HCl with the adsorption rates of 91.2%, 100.0% and 95.7% respectively. No interference exists from coexisting elements except for Ge(IV), Cr(VI),Ti(IV) in inductively coupled plasma-mass spectrometry. The detection limits are 0.27 mug/L, 0.40 mug/L and 0.19 mug/L for Au, Pt and Pd respectively. The results of these elements in standard geological materials are in agreement with certified values with precision of 19.2% RSD for Au (n = 8), 28.1% RSD for Pt (n=8), and 15.6% RSD for Pd (n=8).

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Three kinds of polymer resin supported Pd catalysts were prepared by mixing PdCl2, with alkaline styrene anion exchange resins[D392 -NH2, D382, -NHCH3, D301R, -NH(CH3)(2)], strongly alkaline styrene anion exchanged resin [201 X 7DVB, -NH+ (CH3)(3)] and alkaline epoxy exchange resin (701, -NH2), and hydrogenating in liquid phase at 1.013 X 10(5) Pa. The hydrogenation of furfural was studied under the reaction conditions such as solvent, temperature. Pd content in the supported catalyst and the amount of the catalyst. The yield of hydrogenation reaction of furfural markedly increased to 100% and the selectivity to tetrahydrofurfuryl alcohol increased to over 98% by polymer (alkaline styrene anion exchange resins D392, -NH2, D382, -NHCH3) supported palladium catalysts comparing with the yield over 70% and selectivity over 97% by palladium catalyst, in 50% alcohol-50% water or pure water solution at 1.013 X 10(5) Pa. The relationship between hydrogenation and the structures of functional group in the supporting resin was examined by XPS method.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

以弱碱性苯乙烯系阴离子交换树脂 [D3 92 ,— NH2 ,D3 82 ,— NHCH3,D3 0 1 R,— NH(CH3) 2 ],强碱性苯乙烯系阴离子交换树脂 [2 0 1× 7DVB,— NH+ (CH3) 3]和弱碱性环氧系阴离子交换树脂 (70 1 ,— NH2 )为载体制备了 3种钯 -高分子载体催化剂 .考察了反应条件、高分子载体的种类、钯含量和催化剂用量对糠醛催化加氢生成四氢糠醇反应及催化性能的影响 .在体积分数为 5 0 %的乙醇 -水溶液和水中对糠醛常压液相加氢反应 ,钯 -高分子载体 (阴离子交换树脂 D3 92 ,— NH2 ,D3 82 ,— NHCH3)催化剂均可使糠醛的加氢反应转化率达 1 0 0 % ,生成四氢糠醇的选择性达 98%以上 ,而用金属钯为催化剂的转化率达 70 %以上 ,选择性达97%以上 .同时用 XPS分析了高分子载体催化剂的结构与催化加氢反应性能的关系.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

研究了地质样品中超痕量Au、Pt和Pd的测定方法。采用C 4 1 0阴离子交换树脂在 1 .5mol LHCl条件下对Au、Pt、Pd的吸附率分别为 91 .2 %、1 0 0 .0 %、95 .7%。共存离子除Ge4+ 、Cr6 + 、Ti4+ 外 ,无显著性干扰。用ICP MS测定Au、Pt、Pd的检出限分别为 0 .2 7、0 .4 0和 0 .1 9μg L。当n =8时 ,Au的RSD为 1 9.2 % ;Pt的RSD为 2 8.1 % ;Pd的RSD为 1 5 .6%。

Relevância:

10.00% 10.00%

Publicador:

Resumo:

A new fungus-derived benzodiazepine analogue, 2-hydroxycircumdatin C (1), and a compound which has been isolated from a natural resource for the first time, but has been previously synthesized, namely (11aS)-2,3-dihydro-7-methoxy-1H-pyrrolo[2,1-c][1,4]benzodiazepine-5,11(10H,11aH)-dione (2), along with five structurally related known alkaloids (3-7), were isolated from Aspergillus ochraceus, an endophytic fungus derived from the marine brown alga Sargassum kjellmanianum. Their structures were established on the basis of spectroscopic methods. The absolute configuration of I was determined through CD evidence. Compound 1 displayed significant DPPH radical-scavenging activity with an IC50 value of 9.9 mu M, which is 8.9-fold more potent than that of butylated hydroxytoluene (BHT), a well-known synthetic positive control.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

文昌鱼是介于无脊椎动物脊椎动物之间的一种过渡动物,在进化研究上具有重要意义。但是,近年来由于生存环境的改变和环境污染,其种群数了量正逐渐减少,面临着灭绝的危险。为保护这一珍贵的濒危动物,我们开展了青岛文昌鱼实验室培育的研究,并对其繁殖生物学进行研究。这不但具有一定的理论意义,而且可为实现其全人工养殖奠定基础,具有潜在的应用价值。青岛文昌鱼分别于1996年7月和1998年7月从青岛附近海区捞回,饲养于实验室内。1996年实验分为3组:第一组为136条雌性文昌鱼,第二组为136条雄性文昌鱼,第三组为136条雌雄混合的文昌鱼(雌雄比例为1:1)。1998年实验分两组:第一组为60条雌性文昌鱼,第二组为60条雄性文昌鱼。文昌鱼在实验室内分别饲养至1997年8月和1999年7月。结果表明:(1)实验室饲养的文昌鱼绝大多数都能形成充分发育的性腺,并且其性腺数、怀卵量和卵径大小都与天然海区的文昌鱼没有差别;(2)雌雄分开饲养的文昌鱼在繁殖季节时虽已形成成熟的性腺,但却没有排卵或排精;而雌雄混养的文昌鱼则跟自然海区的文昌鱼一样,正常排卵排精;(3)实验室饲养文昌鱼所产的卵子和精子受精后能正常发育,并形成正常幼虫;(4)在前后两年所饲养的雌性文昌鱼中,都发现有少数个体发生性转换变成雄性的例子,由上述结果可以看出:(1)实验室雌雄混合饲养的文昌鱼性腺可以正常发育,其排放的精卵也可以正常受精发育,这为实现文昌鱼全人工养殖奠定了基础;(2)雌雄分开单独饲养的文昌鱼的性腺可以正常发育,但是在雌雄保持分开的情况下,并不排放精卵,这说明文昌鱼精卵排放可能需要雌雄个体之间相互诱导;(3)连续两年发现雌性文昌鱼可以发生性转换,变成雄性文昌鱼,这一现象属国内外首次报道。本研究不但阐明了实验室饲养文昌鱼性腺发育的特性,而且为实现其全人工养殖,保护这一濒危物种奠定了基础。

Relevância:

10.00% 10.00%

Publicador:

Resumo:

The combined occurrence of both herkogamy and dichogamy in a hermaphrodite species has been considered to strongly favour outcrossing. In this study, we investigated in detail the reproductive ecology of Gentiana straminea Maxim. (Gentianaceae), a hermaphrodite perennial endemic to the Qinghai-Tibet Plateau. In a series of observations and experiments over four consecutive years, we examined whether the combination of dichogamy and herkogamy in individual flowers completely prevents geitonogamous pollen transfer in this species. The mode of floral development clearly indicates that autonomous self-pollination is completely avoided through herkogamy and dichogamy in individual flowers. This implication was confirmed by the breeding experiments, since no seed was produced when flowers were isolated. However, this gentian proved to be highly self-compatible when geitonogamous selfing was artificially induced. Many flowers opened simultaneously on individual plants, the ratio of male to female phase flowers was close to 2:1 in each inflorescence, at the full anthesis phase, and they were randomly distributed amongst the upper, middle and lower parts of each stem's inflorescence. On average, Bombus sushikini Skorikov, the most frequent visitor and only legitimate pollinator of G. straminea, visited nearly two flowers per inflorescence, and four flowers per plant. Among the pollinators' foraging bouts, the proportions of geitonogamous visits to inflorescences or flowers within an individual plant were 29% and 37%, respectively. Therefore, despite the strict dichogamous and herkogamous characteristics of the individual flowers, geitonogamous selfing might still prevail in G. straininea because of the size of its floral displays and the continuous visiting behavior of B. sushkini. (C) 2005 Elsevier SAS. All rights reserved.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

PetroChina and other national petroleum incorporations need rigorous procedures and practical methods in risk evaluation and exploration decision at home and abroad to safeguard their international exploration practice in exploration licence bidding, finding appropriate ratio of risk sharing with partners, as well as avoiding high risk projects and other key exploration activities. However, due to historical reasons, we are only at the beginning of a full study and methodology development in exploration risk evaluation and decision. No rigorous procedure and practical methods are available in our exercises of international exploration. Completely adopting foreign procedure, methods and tools by our national incorporations are not practical because of the differences of the current economic and management systems in China. The objective of this study is to establish a risk evaluation and decision system with independent intellectual property right in oil and gas exploration so that a smooth transition from our current practice into international norm can take place. The system developed in this dissertation includes the following four components: 1. A set of quantitative criteria for risk evaluation is derived on the basis of an anatomy of the parameters from thirty calibration regions national wide as well as the characteristics and the geological factors controlling oil and gas occurrence in the major petroleum-bearing basins in China, which provides the technical support for the risk quantification in oil and gas exploration. 2. Through analysis of existing methodology, procedure and methods of exploration risk evaluation considering spatial information are proposed. The method, utilizing Mahalanobis Distance (MD) and fuzzy logic for data and information integration, provides probabilistic models on the basis of MD and fuzzy logic classification criteria, thus quantifying the exploration risk using Bayesian theory. A projection of the geological risk into spatial domain provides a probability map of oil and gas occurrence in the area under study. The application of this method to the Nanpu Sag shows that this method not only correctly predicted the oil and gas occurrence in the areas where Beibu and Laoyemiao oil fields are found in the northwest of the onshore area, but also predicted Laopu south, Nanpu south and Hatuo potential areas in the offshore part where exploration maturity was very low. The prediction of the potential areas are subsequently confirmed by 17 exploration wells in the offshore area with 81% success, indicating this method is very effective for exploration risk visualization and reduction. 3. On the basis of “Methods and parameters of economic evaluation for petroleum exploration and development projects in China”, a ”pyramid” method for sensitivity analysis was developed, which meets not only the need for exploration target evaluation and exploration decision at home, but also allows a transition from our current practice to international norm in exploration decision. This provides the foundation for the development of a software product “Exploration economic evaluation and decision system of PetroChina” (EDSys). 4. To solve problem in methodology of exploration decision, effort was made on the method of project portfolio management. A drilling decision method was developed employing the concept of geologically risked net present value. This method overcame the dilemma of handling simultaneously both geological risk and portfolio uncertainty, thus casting light into the application of modern portfolio theory to the evaluation of high risk petroleum exploration projects.