动量相关作用和介质效应对中能重离子碰撞动力学的影响

考虑动量相关作用和介质效应，在入射能量E_L/Nucl. = 100，200，400和800 Mev及碰撞参数b = 1.0，3.0和5.0 fm时，对系统~(40)Ca + ~(40)Ca用数值方法求解BUU方程。发现状态方程的动量相关性增加了集体流，即硬化状态方程；而且增强了核物质的阻止本领。能量小于700 Mev时，动量相关作用和介质效应对集体流和状态方程的影响正好相反，二者竞争的总效果使状态方程变软，能量较高时，两者均使状态方程变硬。它们的影响密切依赖于入射能量和碰撞参数

Comparison of steroid substrates and inhibitors of P-glycoprotein by 3D-QSAR analysis

Steroid derivatives show a complex interaction with P-glycoprotein (Pgp). To determine the essential structural requirements of a series of structurally related and functionally diverse steroids for Pgp-mediated transport or inhibition, a three-dimensional quantitative structure activity relationship study was performed by comparative similarity index analysis modeling. Twelve models have been explored to well correlate the physiochemical features with their biological functions with Pgp on basis of substrate and inhibitor datasets, in which the best predictive model for substrate gave cross-validated q(2) = 0.720, non-cross-validated r(2) = 0.998, standard error of estimate SEE = 0.012, F = 257.955, and the best predictive model for inhibitor gave q(2) = 0.536, r(2) = 0.950, SEE = 1.761 and F = 45.800. The predictive ability of all models was validated by a set of compounds that were not included in the training set. The physiochemical similarities and differences of steroids as Pgp substrate and inhibitor, respectively, were analyzed to be helpful in developing new steroid-like compounds. (C) 2004 Elsevier B.V. All rights reserved.

长白山阔叶红松林主要树种及群落冠层光合特征

基于叶片尺度的光强-光合响应测定,结合冠层CO2涡度通量观测,研究了长白山阔叶红松林主要树种及群落冠层的光合特征．结果表明,叶片及冠层光响应过程均可以用非直角双曲线模型很好地表达．蒙古栎具有较高的光补偿点Lcp(28μmol·m-2·s-1)、光饱和点Lsp(>1800μmol·m-2·s-1)及最大净光合速率Pmax(9．96μmol·m-1·s-1),表现为典型的喜阳性特点;色木槭的表观量子效率α(0．066)最大,Lcp(16μmol·m-2·s-1),Lsp(800μmol·m-2·s-1左右)及Pmax(4．51μmol·m-2·s-1)最低,表现为弱阳性特点;红松针叶的α值显著低于阔叶树,但具有较高的Pmax,表现为半喜阳特点．在冠层,α和Pmax都位于温带森林报导值的上限,而Lcp位于下限．冠层光合特征参数与叶片具有较好的一致性,均表现为相对较高的光合能力,但环境胁迫,特别是高的饱和水汽压差可显著降低叶片和冠层的光合能力．

Separation of enantiomers by nanoliquid chromatography and capillary electrochromatography using a bonded cellulose trisphenylcarbamate stationary phase

A cellulose trisphenylcarbamate-bonded chiral stationary phase was applied to nano-liquid chromatography (nano-LC) and capillary electrochromatography (CEC) with nonaqueous and aqueous solutions as the mobile phases. Several chiral compounds were successfully resolved on the prepared phase by nano-LC. The applicability of nonaqueous CEC on a cellulose derivative stationary phase was investigated with the organic solvents methanol, hexane, 2-propanol, and tetrahydrofuran (THF) containing acetic acid, as well as triethylamine as the mobile phases. Enantiomers of warfarin and praziquantel were baseline-resolved with plate numbers of 82 300 and 38 800 plates/m, respectively, for the first eluting enantiomer. The influence of applied voltage, concentration of nonpolar solvent, apparent pH, and buffer concentration in the mobile phase on the electroosmotic flow (EOF) and the mobility of the enantiomers was evaluated. Enantioseparations of traps-stilbene oxide and praziquantel were also achieved in aqueous CEC with plate numbers of 111 100 and 107 400 plates/m, respectively, for the first eluting enantiomer. A comparison between nonaqueous CEC and aqueous CEC based on a cellulose trisphenylcarbamate stationary phase was discussed. Pressure-assisted CEC was examined for the chiral separation of praziquantel and faster analysis with high enantioselectivity was acquired with the proper pressurization of the inlet vial.

国际著名生态学书刊出版商简介

生态学已走过了１００多年的历程。据不完全统计，到目前为止，世界各国已出版发行了超过１０００种有关生态学的专业杂志，出版的书籍更是不计其数。这些书刊对生态学知识的普及传播、对生态学本身的发展起到了重要的作用。为了使我国从事有关生态学教学和科研的工作者更...

The experimental research for production of hydrogen from n-octane through partially oxidizing and steam reforming method

The reaction of producing hydrogen for fuel cell which used normal octane as gasoline or diesel oil reactant through catalytic partial oxidizing and steam reforming method has been researched in the fixed-bed reactor. A series of catalysts that mainly used nickel supported on Al2O3 have been studied. It showed that the activity of the catalyst was increased with the content of nickel by using only nickel supported on Al2O3. However, its activity was not obviously increased when the content of nickel was over 5 wt%. The conversion ratio of normal octane and hydrogen selectivity were higher at higher reaction temperature. The single noble catalyst of palladium had better stability compared with that of platinum catalyst although their activity and selectivity were similar during the experimental reaction temperature. The prepared bimetallic catalyst consisted mainly of nickel and little noble metal of palladium supported on Al2O3. It showed that this catalyst had higher activity and selectivity, especially at lower or higher reaction temperatures compared with single nickel or palladium catalyst, and better stability. ((C) 2001 International Association for Hydrogen Energy. Published by Elsevier Science Ltd. All rights reserved.

虎杖根提取物及分离组分对黄瓜白粉病的作用效果

在实验室内进行了虎杖(Polygonum cuspidatum Sieb.etZucc.)根提取物及其活性组分分离研究,并且对黄瓜白粉病进行了活性测定及温室小区试验。结果表明,无论提取率还是作用效果,乙醇较适合于做为虎杖根提取物的提取溶剂。虎杖根乙醇提取物和乙醚提取物对黄瓜白粉病的EC90值分别为537.85、35.38mg/L,而乙醚提取后残留物的活性很弱,说明乙醇提取物中具有杀菌作用的成分主要存在于乙醚提取物中。用pH梯度分离法对乙醚提取物进行分离,得到3个不同组分,其中以氢氧化钠分离得到的组分对黄瓜白粉病显示了极高的杀菌活性。在温室条件下虎杖乙醇提取物在800～1600mg/L下对黄瓜白粉病的防效相当或优于对照药剂三唑酮。

火山大爆发对长白山东坡历史植被演替的影响

距今800年前,长白山火山曾发生大规模喷发,性质为普林尼式喷发。长白山火山大爆发主要分为两个规模较大的喷发期和火山喷发柱垮塌事件以及其后的若干次小规模喷发,火山喷发释放的大量火山碎屑物在强劲偏西风的作用下主要沉积在长白山东坡,使这一区域的植被数次被毁灭。目前,长白山东坡自下至山上林线是长白落叶松林,与其他坡向的植被差异明显,造成这一现象的原因可能是由于火山喷发的影响。本文通过对泥炭层和火山灰中的花粉孢子分析及炭化木鉴定来还原历史植被,将历史植被的变化同火山活动联系起来,从大时间尺度探讨火山喷发前后长白山东坡植被变化以及火山喷发对植被变化的影响过程,阐明现时长白山东坡的长白落叶松林是火山喷发后形成的过渡性植被群落。

陕北山地红枣集雨微灌技术集成与示范

陕北山地红枣集雨微灌技术综合集成了坡地降雨径流调控技术、山地红枣矮化密植栽培技术及修剪技术,在对微灌技术进行创新的基础上,形成了黄土高原山地红枣微灌技术体系,并在黄土高原丘陵沟壑区第一附区——陕西省榆林市米脂县创建了技术体系应用实体样板,该样板地红枣平均产量达到19 800 kg/hm2,较无灌溉条件(产量4 500~6 000 kg/hm2)增产2~3倍,较管灌条件(产量一般为12 000~15 000 kg/hm2)增产30%~60%,且节水36%以上。在单项技术研究方面,利用Penman-Monteith公式确定了红枣生育期理论耗水量(438.8mm);通过不同灌水量处理的田间试验,初步确定出合理的灌水量区间为396~1 320 m3/hm2;提出了坡地低压滴灌工程新的设计理论,即微地形影响下的均匀度计算方法、滴头设计工作压力取值理论及毛管设计新方法;在此基础上,提出了坡上部采用三项配套技术+低压滴灌、坡下部采用三项配套技术+涌泉根灌+雾喷的工程模式。

玉米地膜覆盖的土壤环境效应

通过田间试验研究了地膜覆盖和露地栽培对玉米的土壤温度、水分、养分、盐分含量和土壤生物学特性及硝酸盐含量的变化。结果表明,在玉米生长前期,地膜覆盖5,10,15,20,25 cm土层的土壤日平均温度比露地提高2.4℃、3.0℃、2.9℃、2.2℃、2.7℃,6~7月份比露地降低1.1℃、0.5℃、0.5℃、0.6℃、0.6℃。地膜覆盖0~10,10~20,20~30,30~40 cm土层的土壤含水量分别比露地增加18.84%、10.67%、11.12%和8.9%。地膜覆盖增强了土壤蔗糖酶和碱性磷酸酶的活性,增加了土壤微生物的数量、CO2浓度、土壤呼吸和土壤NO3--N的含量,减少了土壤氮素的损失。地膜覆盖降低了土壤有机质、氮素、速效磷的含量、过氧化氢酶和脲酶的活性及土壤表层的盐分含量。地膜覆盖提高了玉米的生物量和经济产量。

黄土高原南部3种农田土壤剖面坚实度的变化规律

为了揭示黄土高原南部地区不同质地类型土壤剖面坚实度的变化及其与土壤含水率的定量关系,以黄墡土、土娄土、裸露在地表的粘化层耕作剖面为研究对象,定位观测其0~45 cm土壤坚实度与含水率的变化。结果表明,黄墡土、土娄土、裸露在地表粘化层耕作剖面的犁底层平均坚实度均大于耕层,犁底层平均坚实度较耕层分别高194.8%,87.3%,10.4%;剖面土壤质地越粘其平均坚实度越大;土壤坚实度与含水率呈负相关关系;土壤坚实度变化速率为0时,以上3种土壤剖面临界含水率分别为0.1712,0.1757,0.1835;质地不同的土壤剖面坚实度时空变化特征有差异,其中黄墡土剖面0~20 cm土层土壤坚实度为350~500 kPa,受土壤含水率变化的影响较小;20~30 cm土层土壤的坚实度为500~1400 kPa,不易受外界环境影响;30 cm以下土层土壤坚实度为700~1600 kPa,受土壤含水率变化影响较大。土娄土剖面0~40 cm土层土壤坚实度为600~1200 kPa,受含水率变化影响较大;40 cm以下土层土壤坚实度稳定在1 800 kPa左右。粘化层剖面0~15 cm土层土壤坚实度在2000 kPa左右,受环境影响较...

岷江上游干旱河谷景观边界动态及其影响域

采用遥感和地理信息系统技术,界定了岷江上游干旱河谷的范围,在此基础上分析了岷江上游干旱河谷的边界动态及其影响域.结果表明,岷江上游干旱河谷的范围不断扩大,干旱河谷边界长度增加,边界形状复杂性先增加后降低.岷江上游干旱河谷的边界沿山体迅速向上攀升,1974其最高上限为海拔3128m,1995年为3167m,较1974年抬升了39m;2000年为3181m,比1995年抬升了14m.1974—2000年间岷江上游干旱河谷边界最高上限沿垂直方向向上抬升了53m,平均每年约抬升2m.岷江上游干旱河谷边界的显著影响距离为800m,800～1200m为干旱河谷和周围其它景观影响的过渡区域.干旱河谷外缘800m范围内的区域,是干旱河谷抵抗周围景观影响和外来干扰的缓冲地带,在对岷江上游干旱河谷生态环境进行综合治理的过程中,应对其给与充分关注.

黄土高原旱地连续施用锰肥的土壤效应研究

采用连续浸提形态分级方法,研究了连续施用锰肥17 a后锰的土壤化学特性变化。结果表明:经过长期连续施用锰肥,土壤全锰和DTPA-Mn含量增加不多。土壤DTPA-Mn含量随试验时间的延长呈增加趋势,施锰土壤有效锰提高不多,土壤DTPA-Mn含量只增加了0.4~1.7 mg kg-1。土壤中的锰主要以矿物态存在,占土壤全锰含量的比例为87.3%~91.8%。碳酸盐态、氧化锰态和紧结有机态锰占全锰的比例相当,土壤中各形态锰按含量大致呈矿物态>碳酸盐态>氧化锰态>紧结有机态>松结有机态>交换态的顺序。施入土壤的锰肥有91.1%~98.6%进入碳酸盐结合态、氧化锰结合态、紧结有机态和矿物态,只有很少一部分仍留在有效态锰库中。交换态和松结有机态锰对土壤锰的有效性起着主要作用,可以反映土壤锰的供给状况,碳酸盐态和紧结有机态锰不能反映土壤锰的有效性。

沈阳市域森林生态系统服务功能价值评估

采用费用支出法、机会成本法、替代成本法等方法对沈阳市森林生态系统的涵养水源、调节气候、固碳释氧、保持土壤、净化环境、旅游等生态功能价值进行了初步估算。结果表明,沈阳市森林生态系统服务功能总价值为359.631亿元,其中,直接经济价值为4.374亿元、涵养水源价值为3.652亿元、调节气候价值为281.5亿元、固碳释氧价值为34.194亿元、保持土壤价值为0.699亿元、净化环境价值为35.133亿元、旅游价值为800万元。

细辛精油和4种化学药剂对黄瓜灰霉病菌的抑制作用

采用菌丝生长速率法及孢子萌发法分别测定了细辛精油和4种化学药剂(30%嘧霉胺EC、50%双福生WP、75%百菌清WP、70%正品甲津托WP)对引起黄瓜灰霉病的灰葡萄孢菌菌丝生长和孢子萌发的抑制作用。结果表明,供试药剂对灰葡萄孢菌的菌丝生长和孢子萌发均有抑制作用,且对孢子萌发的抑制效果明显好于对菌丝生长的抑制效果;百菌清对灰葡萄孢菌菌丝生长的抑菌效果最好,EC50为1.6231mg/L;双福生对灰葡萄孢菌孢子萌发的抑制效果最好,EC50为0.0042mg/L;细辛精油对黄瓜灰葡萄孢菌的抑菌效果与其他4种化学药剂相比效果较差,对菌丝生长的EC50为159.580mg/L,对孢子萌发的EC50为71.1840mg/L,虽然其EC50偏高,但作为纯植物提取物,其抑菌中浓度低于160mg/L。