历史查询   



 为了更好的帮助您理解掌握查询词或其译词在地道英语中的实际用法，我们为您准备了出自英文原文的大量英语例句，供您参考。 
With this technique the needle is kept within the orbital cavity throughout and aimed in a wide open angle toward the particularly thin ethmoidal wall of the orbita.


The ethmoidal region and cranial adaptations of the neotropical aquatic snake Helicops infrataeniatus Jan, 1865 (Serpentes, Colu


The ethmoidal region of the snake Helicops infrataeniatus is described on the basis of serial sections.


Fos expression in the rat parabrachial and K?llikerFuse nuclei after electrical stimulation of the trigeminal ethmoidal nerve a


Feeders are anterior and/or posterior ethmoidal arteries and the external carotid system also contributes.

 更多 


 Fineness modulus (F. M.) has served as an index of fineness of aggregates since it was first introduced by Prof. Duff A. Abrams in 1918. In the concrete mix design, the F. M. of sand governs the sand content and hence the proportions of other ingredients. But there are undesirable features in F. M.: it does not represent the grading of sand and manifests no significant physical concept.Prof. suggested an "average diameter" (d_(cp)) in 1943 as a measure of fineness of sand. In 1944, d_(cp) was adopted in 278144... Fineness modulus (F. M.) has served as an index of fineness of aggregates since it was first introduced by Prof. Duff A. Abrams in 1918. In the concrete mix design, the F. M. of sand governs the sand content and hence the proportions of other ingredients. But there are undesirable features in F. M.: it does not represent the grading of sand and manifests no significant physical concept.Prof. suggested an "average diameter" (d_(cp)) in 1943 as a measure of fineness of sand. In 1944, d_(cp) was adopted in 278144 as national standard to specify the fine aggregate for concrete in USSR. It was introduced to China in 1952 and soon becomes popular in all technical literatures concerning concrete aggregates and materials of construction.After careful and thorough investigation from ordinary and special gradings of sand, the equation of d_(cp) appears to be not so sound in principle and the value of d_(cp) computed from this equation is not applicable to engineering practice. The assumption that the initial average diameter (ν) of sand grains between consecutive seives is the arithmetical mean of the openings is not in best logic. The value of an average diameter computed from the total number of grains irrespective of their sizes will depend solely on the fines, because the fines are much more in number than the coarses. Grains in the two coarser grades (larger than 1.2 mm or retained on No. 16 seive) comprising about 2/5 of the whole lot are not duly represented and become null and void in d_(cp) equation. This is why the initiator neglected the last two terms of the equation in his own computation. Furthermore, the value of d_(cp) varies irregularly and even inversely while the sands are progressing from fine to coarse (see Fig. 4).As F. M. is still the only practical and yet the simplest index in controlling fineness of sand, this paper attempts to interpret it with a sound physical concept. By analyzing the F. M. equation (2a) in the form of Table 9, it is discovered that the coefficients (1, 2…6) of the separate fractions (the percentages retained between consecutive seives, a1, a2…a6) are not "size factors" as called by Prof. H. T. Gilkey (see p. 93, reference 4), but are "coarseness coefficients" which indicate the number of seives that each separate fraction can retain on them. The more seives the fraction can retain, the coarser is the fraction. So, it is logical to call it a "coarseness coefficient". The product of separate fraction by its corresponding coarseness coefficient will be the "separate coarseness modulus". The sum of all the separate coarseness moduli is the total "coarseness modulus" (M_c).Similarly, if we compute the total modulus from the coefficients based on number of seives that any fraction can pass instead of retain, we shall arrive at the true "fineness modulus" (M_f).By assuming the initial mean diameter (ν') of sand grains between consecutive seives to be the geometrical mean of the openings instead of the arithmetical mean, a "modular diameter" (d_m), measured in mm (or in micron) is derived as a function of M_c (or F. M.) and can be expressed by a rational formula in a very generalized form (see equation 12). This equation is very instructive and can be stated as a definition of mqdular diameter as following:"The modular diameter (d_m) is the product of the geometrical mean ((d_0×d_(1))~(1/2) next below the finest seive of the series and the seive ratio (R_s) in power of modulus (M_c)." If we convert the exponential equation into a logarithmic equation with inch as unit, we get equation (11) which coincides with the equation for F. M. suggested by Prof. Abrams in 1918.Modular diameter can be solved graphically in the following way: (1) Draw an "equivalent modular curve" of two grades based on M_c (or F. M.) (see Fig. 6). (2) Along the ordinate between the two grades, find its intersecting point with the modular curve. (3) Read the log scale on the ordinate, thus get the value of the required d_m corresponding to M_c (see Fig. 5).As the modular diameter has a linear dimension with a defin  細度模數用為砂的粗細程度的指標,已有三十餘年的歷史;尤其是在混凝土的配合上,砂的細度模數如有變化,含砂率和加水量也要加以相應的調整,才能維持混凝土的稠度(以陷度代表)不變。但是細度模數有兩大缺點,一個是模數的物理意義不明,另一個是模數不能表示出砂的級配來。蘇聯斯克拉姆塔耶夫教授於1943年提出砂的平均粒徑(d_(cp))來,以為砂的細度指標;雖然平均粒徑仍不包含級配的意義,但是有了比較明確的物理意義,並且可以用毫米來度量,這是一種新的發展。不過砂的細度問題還不能由平均粒徑而得到解决,且平均粒徑計算式中的五項,僅首三項有效,1.2和2.5毫米以上的兩級粗砂在計算式中不生作用,以致影響了它的實用效果。本文對於平均粒徑計算式的創立方法加以追尋和推演,發現其基本假設及物理意義,又設例演算,以考察其變化的規律性;認為細度模數還有其一定的實用價值,不能為平均粒徑所代替。至於補救細度模數缺點的方法,本文試由模數本身中去尋找;將模數的計算式加以理論上的補充後,不但能分析出模數的物理意義,並且還發現模數有細度和粗度之別。根據累計篩餘計算出來的F.M.應稱為“粗度模數”,根據通過量計算出來的才是“細度模數”。假定兩隣篩间的顆粒是... 細度模數用為砂的粗細程度的指標,已有三十餘年的歷史;尤其是在混凝土的配合上,砂的細度模數如有變化,含砂率和加水量也要加以相應的調整,才能維持混凝土的稠度(以陷度代表)不變。但是細度模數有兩大缺點,一個是模數的物理意義不明,另一個是模數不能表示出砂的級配來。蘇聯斯克拉姆塔耶夫教授於1943年提出砂的平均粒徑(d_(cp))來,以為砂的細度指標;雖然平均粒徑仍不包含級配的意義,但是有了比較明確的物理意義,並且可以用毫米來度量,這是一種新的發展。不過砂的細度問題還不能由平均粒徑而得到解决,且平均粒徑計算式中的五項,僅首三項有效,1.2和2.5毫米以上的兩級粗砂在計算式中不生作用,以致影響了它的實用效果。本文對於平均粒徑計算式的創立方法加以追尋和推演,發現其基本假設及物理意義,又設例演算,以考察其變化的規律性;認為細度模數還有其一定的實用價值,不能為平均粒徑所代替。至於補救細度模數缺點的方法,本文試由模數本身中去尋找;將模數的計算式加以理論上的補充後,不但能分析出模數的物理意義,並且還發現模數有細度和粗度之別。根據累計篩餘計算出來的F.M.應稱為“粗度模數”,根據通過量計算出來的才是“細度模數”。假定兩隣篩间的顆粒是兩篩篩孔的幾何平均值,以代替數學平均值(即斯氏平均?  The present paper reports studies on the relative rate of decomposition of nine different oil cakemeals [soybean, peanut, sesame, rape seed, cotton seed(with and without hull), chinese tallow seed (with and without hull)]. In the course of decomposition of the different oil cakemeals, freguent measurement were made of the quantity of evolved CO_2 gas, and amount of the NH_4~+, NO_3~, and NO_2~ nitrogen formed at the given intervals of the day. These measurement served as indices of the intensity of decomposition... The present paper reports studies on the relative rate of decomposition of nine different oil cakemeals [soybean, peanut, sesame, rape seed, cotton seed(with and without hull), chinese tallow seed (with and without hull)]. In the course of decomposition of the different oil cakemeals, freguent measurement were made of the quantity of evolved CO_2 gas, and amount of the NH_4~+, NO_3~, and NO_2~ nitrogen formed at the given intervals of the day. These measurement served as indices of the intensity of decomposition and rate of ammonification and nitrification of the oil cakemeals that may be occur in the soil. These studies were performed in the laboratory, under room temperature condition of the summer season. All cakes were ground into meals to such particle size as to pass through a 20mesh sieve. The cakemeals were separately mixed with cultivation soil in the proportion of one part of cakemeal to hundred parts by weight of soil. The soil used was of alluvial origin, low in organic matter and somewhat sandy in texture. It was found that decomposition of the cakemeals began soon after their application to the soil. The daily evolution of CO_2 reached its maximum for about one week. Immediately after that, the daily evolution of CO_2 declined rapidly to a such lower level and attained a rather steady declining rate after about two weeks. The trends were common in character irrespective of the kind of the cakemeals. Among the organic constituents of tile cakemeals that underwent into decomposition in the early days, nitrogeneous organic compou ads seemed to be of major importance. The production of ammonium compounds as a result of ammonification followed a trend similar to that shown by the evolution of CO_2. The maximum rate of ammonification was noticed sometime before the evolution of Co_2 had reached a maximum. The positive correlation existing between the total nitrogen content of the oil cakes and the rate of ammonification was evident. Other factors, however seemed to be also affecting the status of transformation of Nitrogen compounds. Nitrate compounds began to appear soon after ammonification had proceeded to an appreciable degree. In the course of decomposition their accumulation in the soil increased steadily with the time. Small amounts of nitrites were found under the experiment conditions which were characterized by low moisture content (25%) of the soil and meal mixtures. From the quantity of the total available nitrogen accumulated at different intervals in the course of decomposition as in the case here given, it seemed that some nitrogen might be lost through volatilization of ammonium compounds, since the soil was alkaline in reaction (the soil here used had a PH value of 7.2) Soaking the cake meals with water, limewater, or strawash extract as sometimes practiced by the local farmers in some districts in Chekiang province brought about the effect of hastening ammonification and nitrification processes. But, gain in readiness of availability of the meals by this hastening effect might not compensate for the loss in total amount of available nitrogen formed. The loss was particularly evident when the cakemeals were pretreated with limewater or strawash extract. It is believed that the alkaline reaction of the treated cakemeals accounts for this loss. The relative readiness of decomposition of the different oil cakemeals followed in descending order: soybean, sesame, peanut, Cotton seed (without hulls)>Cotton seed (with hulls), rape seed>Chinese tallow seed (with and without bulls). Similarly, the relative total amount of available nitrogen (including ammonium and nitrate nitrogen) formed during decomposition shows in the following order: soybean, peanut, sesame, chiness tallow seed(without hulls)>Cotton seed (with and without hulls)>rape seeds>Chiness tallow seed (with hlls).  研究了浙江省施用的九种主要餅肥在土壤中分解的情况,各种餅肥都經磨碎,并通过20孔篩。实驗証明,在夏天的温度下,餅肥施入土壤后即迅速分解,它的分解最盛时期是在一星期左右,此后即迅速下降,到二星期后,即漸趋穩定。餅肥施入土壤后,铵态氮的大量發生是在一星期以內,此后即迅速降低,轉化成硝酸态氮。硝酸态氮在一星期到二星期的时間内开始大量發生,到二星期后就漸趋穩定。土壤中有效态氮总量在各个形态轉化的过程中,有顯著的減少趋势。餅肥在施入土壤前用石灰、草灰或水处理一星期,可提早土壤中有效氮的發生,其中單用水处理的效果尤其好。实驗証明,用石灰或草灰处理餅肥,使有效态氮大量損失,而用水处理則沒有这种情况。在本实驗的条件下,各种餅肥的分解速率依次为:豆餅、芝麻餅、花生餅、棉仁餅>棉籽餅、生菜餅、熟菜餅>桕餅、青餅。各种餅肥中氮素化合物转化后所產生的有效态氮总量依次为:豆餅、花生餅、芝麻餅、青餅>棉仁餅、生菜餅、棉籽餅>熟菜餅>桕餅。  In order to investigate the effect of operating variabls on the yield of aromatics,a certain fraction of a straight run gasoline containing 48.4% (wt.)naphthenes was catalytically converted into aromatics over a bed of 100 ml 14—20 mesh,granular,platforming catalyst under various opera ting conditions.The ranges of these investigations were:temperature 430— 510℃,pressure 20—50 atm.,WHSV 1.58—6.32 and hydrogenoil molar ratio 4:1—10:1.The single pass fresh hydrogen process was adopted. The result of data treatment... In order to investigate the effect of operating variabls on the yield of aromatics,a certain fraction of a straight run gasoline containing 48.4% (wt.)naphthenes was catalytically converted into aromatics over a bed of 100 ml 14—20 mesh,granular,platforming catalyst under various opera ting conditions.The ranges of these investigations were:temperature 430— 510℃,pressure 20—50 atm.,WHSV 1.58—6.32 and hydrogenoil molar ratio 4:1—10:1.The single pass fresh hydrogen process was adopted. The result of data treatment implied that the following secondorder reaction rate expression correlates the aromatics production rate r with the operating variables satisfactorily. r=r_0(1bx)~2, where x=aromatics yield based on feed(wt.%),and r_0 and b are constants. Superfacially r_0 may be regarded as the reaction rate constant,whereas b as a stochiometric coefficient of the equivalent kinetic equation.Both are functions of the operating temperature,pressure and hydrogenoil molar ratio. For 4:1 hydrogenoil molar ratio,which seems to be one of the most promising operating conditions,the differential and integral forms of the rate equation for aromatics yield are as follows: The apparent activation energy of the aromatics yield reaction by platforming under the conditions investigated,therefore,equals to 33,500 cal/gmmol.The values of b at isobaric conditions may be correlated as: In b_(50)=8200/RT17.5/R The significance of b is discussed thermodynamically. Considerable variations,though not large,in aromatic yield were observed when the hydrogenoil molar ratio changed from 4:1 to 10:1.For example,at 30 atm.,490℃,this effect may be expressed by r=(p/186p+144)×10~5(1bx)~2, where p=partial pressure of the feed stock,atm. Besides,the relative initial rates of C_8 aromatics,toluene and benzene formation were found to be in the increasing order of their molecular weights.Thus under certain operating conditions the initial rate of C~8 aromatics formation was 2.5 times that of the toluene initial formation rate,and 20 times that of the benzene formation rate.  用直馏汽油的某一馏分在装有100毫升14—20筛眼颗粒形铂重整催化剂的反应设备中,进行单程纯氢操作的铂重整反应条件试验以考察芳烃的生成与反应条件变化的关系.试验的反应条件为:溫度430—510°压力20—50大气压,空间流速1.58—6.32重量/重量/小时,氢油分子比4:1—10:1.处理所获试验数据的结果,发现芳烃生成速度γ可用下列二次反应式来关连:   << 更多相关文摘 
相关查询  



CNKI小工具

在英文学术搜索中查有关筛的的内容

在知识搜索中查有关筛的的内容

在数字搜索中查有关筛的的内容

在概念知识元中查有关筛的的内容

在学术趋势中查有关筛的的内容



