服务现代农业,推进国际交流——对《中国旱地农业》一书的评价

由于受区域降水的限制,又缺乏灌溉条件,旱地农业通常被认为是一种风险性大的产业。但是,随着科学技术的进步和水资源紧缺的不可逆转,发展半干旱和半湿润地区的旱地农业将不再是一种不得已的被动做法,而成为一种面向未来的积极对策。在最大限度减少灌溉用水的条件下提高农田产量,同时改善生态环境并降低经济成本是现代农业科学技术所力求实现的目标。旱地农业日益受到重视的另一个重要原因是,旱地农业与灌溉农业的互通性增强了,应将它们看作是一个连续系统,两者都强调以充分利用自然降水为基础,都用消耗单位水量形成多少生产量来评价。在节水灌溉农业中也必须善于运用旱作技术,而在发展旱地农业中也提倡通过集水等措施实施补充灌溉。旱地农业和旱作技术的重要性加大了,其内涵也扩展了。在这一背景下编著出版《中国旱地农业》这一大型专著无疑具有十分重要的意义。自20世纪80年代以来国内已有多部关于旱地农业的书籍问世,各具特色,对于该领域的深入研究和发展旱区生产起到了积极推动作用。但总体看,多数出版物在系统性和综合性上都还有不足,或偏重于旱农技术本身的介绍,或仅针对某一特定区域进行论述,或包含的学科领域有限。李生秀等编著的《中国旱地农业》一书除了抓住上述旱地农业...

黄土高原的林草资源和适宜覆盖率

对于一个国家或地区来说 ,为了在社会与自然界之间建立和谐的作用关系 ,使保护森林和发展林业与社会经济发展相协调 ,以维持区域生态平衡 ,必需具备相应的森林资源水平 ,即一定的森林覆盖率。黄土高原的植被在总体上属温带草原区域 ,其基本特点在于 ,自东南而西北具有依次更替的地带性分布规律 ,即依次分布有森林、森林草原、典型草原和荒漠草原等 4个植被带 ,其中草原占有重要的位置。因此 ,在研究该地区适宜覆盖率时 ,必须将草地资源包括在内 ,确定适宜的林草覆盖率。1　林草植被资源本项研究的主体是晋、陕、蒙、甘、宁 5省 (区 )的黄土高原水土流失区 ,计 1 0 6个县 ,其面积为 2 7 3× 1 0 4 ｋｍ2 ,占典型黄土高原面积 38× 1 0 4 ｋｍ2 的 71 8%。该地区现有林地面积 938× 1 0 4 ｈｍ2 ,占总面积的 34 4% ,其中有林地和灌木林地 41 7× 1 0 4 ｈｍ2 ,森林覆盖率 1 5 2 % ,宜林地 42 6× 1 0 4 ｈｍ2 ;草地面积 842× 1 0 4 ｈｍ2 ,占总面积的 30 9%。这些林地和草地 ,从总体布局来看 ,南部半湿润区森林面积较多 ,北...

沈阳城市森林三维绿量模拟及其影响因子

为探求便捷有效的小面积城市森林三维绿量的测算方法,根据林木生长的分形原理,采用逐步回归方法获取了沈阳城市森林三维绿量的13个模拟方程,并对其影响因素进行分析.结果表明:13个模拟方程的决定系数(R2)在0.612~0.842,残差分析没有呈现明显图样,模型精度均在87%(α=0.05)和83%(α=0.01)以上,其中最便捷的模拟方程是ln■=7.468+0.926 lnx1[■为模拟三维绿量,x1为每公顷胸高断面积(SDB)].模拟方程的标准回归系数与16个树木特征间的相关关系显示,影响沈阳城市森林三维绿量的最主要因素是每公顷胸高断面积(SDB).

Precipitation-use efficiency along a 4500-km grassland transect

National Natural Science Foundation of China [30590381, 40971027]; State Key Technologies RD Program [2006BAC08]; Chinese Academy of Sciences ; National Key Research and Development Program [2010CB833501]

Effect of shear on the crystallization behavior of glass bead filled polypropylene

Linkam CSS450 optical shearing stage, wide-angle X-ray diffraction (WAXD) and small-angle X-ray scattering(SAXS) were used to investigate the effect of shear on crystal structure and crystallization morphology of the glass bead filled polypropylene( PP). The results indicate that the glass bead worked as nucleating agent for the glass bead filled PP, compared with pure PP it restrained the formation of beta-crystal after shear treatment. When the mean size of glass bead is smaller(4 mu m) shear rate had less effect on the formation of beta-crystal of PP obviously.

ELECTROCHEMICAL DEPOSITION OF MAGNESIUM IN ETHEREAL GRIGNARD SALT SOLUTION WITH IONIC LIQUID ADDITIVE

The electrochemical deposition of magnesium was investigated in ethereal Grignard salt solution with tetraethylammonium bistrifluoro-methanesulfonimidate additive, using cyclic voltammetry, potentiostatic transients, and scanning electron microscope measurements. The voltammograms showed the presence of reduction and oxidation peaks associated with the deposition and dissolution of magnesium. From the analysis of the experimental current transients, it was shown that the magnesium deposition process was characterized as a three-dimensional nucleation. The deposited product obtained from potentiostatic reduction presented a generally uniform and dense film.

Influence of the degree of grafting on the morphology and mechanical properties of blends of poly(butylene terephthalate) and glycidyl methacrylate grafted poly(ethylene-co-propylene) (EPR)

Poly(ethylene-co-propylene) (EPR) was functionalized to varying degrees with glycidyl methacrylate (GMA) by melt grafting processes. The EPR-graft-GMA elastomers were used to toughen poly(butylene terephthalate) (PBT). Results showed that the grafting degree strongly influenced the morphology and mechanical properties of PBT/EPR-graft-GMA blends. Compatibilization reactions between the carboxyl and/or hydroxyl of PBT and epoxy groups of EPR-graft-GMA induced smaller dispersed phase sizes and uniform dispersed phase distributions. However, higher degrees of grafting (>1.3) and dispersed phase contents (>10 wt%) led to higher viscosities and severe crosslinking reactions in PBT/EPR-graft-GMA blends, resulting in larger dispersed domains of PBT blends. Consistent with the change in morphology, the impact strength of the PBT blends increased with the increase in EPR-graft-GMA degrees of grafting for the same dispersion phase content when the degree of grafting was below 1.8. However, PBT/EPR-graft-GMA1.8 displayed much lower impact strength in the ductile region than a comparable PBT/EPR-graft-GMA1.3 blend (1.3 indicates degree of grafting).

Single-molecule dynamics reveals cooperative binding-folding in protein recognition

The study of associations between two biomolecules is the key to understanding molecular function and recognition. Molecular function is often thought to be determined by underlying structures. Here, combining a single-molecule study of protein binding with an energy-landscape-inspired microscopic model, we found strong evidence that biomolecular recognition is determined by flexibilities in addition to structures. Our model is based on coarse-grained molecular dynamics on the residue level with the energy function biased toward the native binding structure ( the Go model). With our model, the underlying free-energy landscape of the binding can be explored. There are two distinct conformational states at the free-energy minimum, one with partial folding of CBD itself and significant interface binding of CBD to Cdc42, and the other with native folding of CBD itself and native interface binding of CBD to Cdc42. This shows that the binding process proceeds with a significant interface binding of CBD with Cdc42 first, without a complete folding of CBD itself, and that binding and folding are then coupled to reach the native binding state.

An encapsulation of the rare earth complex in modified mesoporous molecular sieve MCM-41

The encapsulation of a rare earth (RE) complex Eu(DBM)(3)phen in modified S1-MCM-41 with 3-aminopropyltriethoxysilane is reported for the first time. The luminescence intensity of the RE complex in the modified Si-MCM-41 is about 9 times as strong as in unmodified Si-MCM-41 and the luminescence of the RE complex in the modified SI-MCM-41 has good color purity.

Electrochemistry of vanadium hexacyanoferrate film

Two stable redox couples, accompanying clear color switches between yellow green and blue, can be observed when the VHCF-coated film platinum electrodes are cyclic potential scanned in 3.6 M H2SO4 and 0.2 M K2SO4 electrolyte solution. Electrochemical results and in situ Fourier transfer infrared (FT-IR) spectroscopy demonstrate that the redox reaction of the electroactive iron sites is related to the first redox couple (E-1/2 = 0.81 V) while the second redox couple (E-1/2 = 1.01 V) is due to the redox reactions of the electroactive vanadyl ions. Under the proper conditions, such as in high acidic solutions or thin films (deposition time is less than 2 min) and so on, the third redox couple (E-1/2 = 0.89-0.94 V) can be observed on the cyclic voltammograms, which originates from the redox reactions of the interstitial vanadyl ions. This electrochemical reaction mechanism is investigated by in situ probe beam deflection technique, exchange of K+ ions accompanies with redox reaction of the iron sites, but for redox reaction of the vanadyl ions, both H+ ions, K+ ions and water molecules are involved.

EPITAXIAL BEHAVIOR OF HDPE ON THE BOUNDARY OF HIGHLY ORIENTED IPP SUBSTRATES

The epitaxial crystallization behavior of high-density polyethylene on the boundary of highly oriented isotactic polypropylene (iPP) substrates has been investigated by means of atomic force microscopy (AFM) and transmission electron microscopy (TEM). The results obtained from AFM and TEM indicate that the epitaxial nucleation of HDPE on the highly oriented iPP substrates occurs earlier than that in the pure HDPE phase, i.e., homogeneous nucleation. Therefore the epitaxially grown HDPE lamellae can grow across the boundary of the iPP substrate into the HDPE spherulitic phase with the epitaxial orientation relationship remaining.

铕和铽与3,4-呋喃二甲酸双核配合物的合成、表征及其晶体结构

本文首次合成了铕(Ⅲ)和铽(Ⅲ)与3,4-呋喃二甲酸配合物,研究了它们的IR、DTA、TG、DTG和荧光光谱等性质,并完成了单晶的晶体分析。结果表明,配合物为〔Ln·HL_2(H_2O)_2〕_2·2H_2O(Ln=Eu(Ⅲ),Tb(Ⅲ);H_2L=3,4-呋喃二甲酸),属单斜晶系,P2/c空间群,Z=2,晶胞参数对铕和铽配合物分别为α=10.842(1),10.801(4);b=8.725(2),8.664(2);c=16.366(4),16.308(6)A;β=93.50(1),93.67(3)°;V=1545.3(5),1523.0(8)A~3。

斑马鱼肌肉发育相关基因克隆、表达与功能分析

本文主要研究在斑马鱼胚胎发育过程中参与肌肉发育的相关基因，克隆了四个在体节和肌肉中表达的基因全长，分析了基因的时空表达特征，并对其中两个基因进行了过表达，分析其在体节形成和肌肉发生过程中的功能。 从斑马鱼中克隆到甲状腺激素受体相关蛋白基因TRAP150。原位杂交分析TRAP150表达在近轴细胞的慢肌和体节的快肌，表达模式与MyoD的模式相近；并表现出肌肉特异性表达，TRAP150在体节形成和肌肉发生早期高水平说明TRAP150在肌肉分化过程发挥着重要的作用。此外，在胚胎的心脏中也检测到TRAP150的表达。在斑马鱼胚胎过量表达TRAP150造成MyoD在近轴中胚层的过量表达，而对MyoD在近轴细胞的表达影响不明显；由于MyoD在近轴中胚层的表达将诱导快肌的形成，因此过量表达TRAP150将可能导致快肌的增多；从过量表达的结果分析，TRAP150在MyoD的上游正向调控MyoD的表达，是诱导快肌的分化的重要基因。 从斑马鱼中克隆到双特性酪氨酸调控激酶新基因DYRK2。RT-PCR结果表明DYRK2具有母源性表达的特点，并且在36小时前各个时期都有表达。DYRK2在体节形成后表达在体节的近轴细胞中，大约在15个体节时检测到在快肌部位表达，18小时后在胚胎肌肉组织、脑部以及眼睛表达。DYRK2在斑马鱼胚胎发育过程中与体节和肌肉发生相关的基因之一，并可能参与脑和眼睛的发生。在斑马鱼胚胎中过量表达DYRK2导致肌肉标记基因MyoD的表达出现了很大的变化，注射侧MyoD在近轴细胞和近轴中胚层过量表达，尤其是在未形成体节的体节前体中胚层，注射侧的MyoD有大范围的高表达，而在正常一侧没有表达。MyoD的过量表达说明斑马鱼胚胎早期DYRK2通过调控MyoD的表达影响慢肌的分化。 克隆得到斑马鱼的血细胞生成的PBX1互作蛋白基因HPIP1。RT-PCR结果表明HPIP1在斑马鱼胚胎表达具有母源性，但是原位杂交的检测一直到10个体节时才检测到，说明HPIP1一直到肌肉分化后才大量表达，可能在肌肉的成熟阶段起作用。当胚胎发育到18小时，HPIP1表达在所有体节中，前端的较早形成的体节中表达量比晚形成的体节表达量高，也符合HPIP1参与肌肉成熟过程的判断。HPIP1还表达在胚胎的眼部周围，说明HPIP1可能参与到眼部肌肉的形成。 在斑马鱼中克隆的Chp-1相似蛋白基因CHORDC1。在3个体节时，CHORDC1表达在脊索两侧的近轴细胞中，而在5个体节时CHORDC1在表达在体节中，这个特点与MyoD的表达很相似，与MyoD在体节中表达不同的是，CHORDC1也在体节前体中胚层中表达，这与Myf5的表达特点相似，CHORDC1紧随着MyoD，Myf5的高表达说明CHORDC1在肌肉细胞的分化的早期即参与肌肉的发育，而其高表达量也说明CHORDC1在这个过程中可能起到非常重要的作用。CHORDC1在近轴中胚层的表达与MyoD，Myf5有不同的特点，这种不同表现在其在近轴中胚层的表达不仅仅限于快肌和慢肌，而且由后到前的逐渐扩展。而且，CHORDC1在心肌中也表达说明其不仅在骨骼肌中发挥作用。综合CHORDC1的表达特点可以认为其对肌肉的作用不限于特定肌肉类型，广泛参与到各种肌肉的发育过程

Effects of rearing temperature and density on growth, survival and development of sea cucumber larvae, Apostichopus japonicus (Selenka)

In laboratory conditions, effects of rearing temperature and stocking density were examined on hatching of fertilized egg and growth of auricularia larvae of Apostichopus japonicus respectively. Data series like larval length and density, metamorphic time, and survival rate of the larvae were recorded. Statistics showed that for A. japonicus, survival rate (from fertilized egg to late auricularia) decreased significantly with the increasing rearing temperature (P < 0.05). At different temperatures SGR was statistically significant as well (P < 0.05) from day 1, and maximal SGR was found on day 9 at 24A degrees C (159.26 +/- 3.28). This study clearly indicated that at low temperature (< 24A degrees C), metamorphic rate was remarkably higher than at higher temperature (> 26A degrees C). Hatching rate was significantly different between 0.2-5 ind./ml groups and 20-50 ind./ml groups. Rearing larvae at the higher density had the smaller maximal-length, whereas needed longer time to complete metamorphosis. This study suggested that 21A degrees C and 0.4 ind./ml can be used as the most suitable rearing temperature and stocking density for large -scale artificial breeding of A. japonicus's larvae.