Research Development of Higher Fungi in Plant Protection

高等真菌具有多种农用生物活性。概述了高等真菌在杀虫、抑菌、抗病毒、杀线虫活性等方面的研究进展,重点介绍高等真菌代谢产物作为杀菌剂的研究与应用,旨在为高等真菌在植物保护领域的进一步研究利用提供依据。     

猪毛蒿精油对小菜蛾的杀虫活性及其化学成分分析

测定了猪毛蒿精油对小菜蛾的杀虫活性,同时对其化学成分进行了鉴定。结果表明:猪毛蒿精油对小菜蛾有较好的杀虫活性。触杀和熏蒸试验中,在浓度分别为0.24 g/mL和0.83μL/L处理24 h后,校正死亡率可达到100%;胃毒试验中,浓度为0.2 g/mL的处理组在48 h后,校正死亡率为92.65%;驱避试验中,体积分数为3%的处理组驱避率为90.17%。通过GC-MS分析,从猪毛蒿精油中共鉴定出43种化学成分,主要的成分是甲基丁香酚(27.31%)、丁香酚(8.54%)、反式石竹烯(7.22%)和氧化石竹烯(6.07%)。     

三个芜菁品种源/库活性变化差异的比较

在本试验所研究的芜菁三个品种中,其生长状况基本相似,出苗后前期,地上部生长迅速,地下部生长较缓慢,且根冠比小于0.2,但是后期,地下部迅速生长,地上部生长较为缓慢,根冠比增加。在源/库活性方面,3个芜菁品种均在前期处于缓慢增长的趋势,后期呈现不同程度的变化。     

苦参生物活性研究进展

苦参的活性成分主要是生物碱和黄酮类化合物。许多研究发现,苦参在医疗方面具有抗肿瘤活性及抗肝损伤、抗溃疡、抗生育、抗炎抑菌、抗心率失常、抗病毒和治疗慢性肝炎等作用;在农业上,苦参对多种病虫害具有毒杀和抑制作用,并具有杀鼠活性。文章对以上研究进行了综述,并指出了苦参今后的研究方向。     

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 高等真菌具有多种农用生物活性。概述了高等真菌在杀虫、抑菌、抗病毒、杀线虫活性等方面的研究进展，重点介绍高等真菌代谢产物作为杀菌剂的研究与应用，旨在为高等真菌在植物保护领域的进一步研究利用提供依据。     

真瓣鳃目5种海洋贝类生物活性的研究

[目的]研究真瓣鳃目5种海洋贝类提取物的体外抗肿瘤和免疫调节活性。[方法]利用植物化学分析方法对这5种海洋贝类成分进行初步分离,将其乙醇提取液分为石油醚、乙酸乙酯、正丁醇和水4个不同极性部分,并对这些成分的抗肿瘤及免疫调节活性进行研究。[结果]5种贝类的乙醇提取物均有一定的抑制肿瘤细胞生长的作用。大多数组分对人早幼粒细胞白血病细胞HL-60有较强的抑制作用,但只有文蛤的正丁醇部分对人胃癌细胞BGC-823、四角蛤蜊的石油醚部分和文蛤的正丁醇部分对人肺癌细胞A549以及缢蛏的石油醚部分、杂色蛤仔的乙酸乙酯部分、杂色蛤仔和文蛤的正丁醇部分和青蛤的水提部分等组分对人肝癌细胞SMMC-7721有明显的抑制作用。5种贝类的大多数提取组分对小鼠脾淋巴细胞的增殖有调节作用,其中文蛤和缢蛏的增殖作用较强,文蛤的水提部分和石油醚部分对脾淋巴细胞的增殖率分别为670%和370%,缢蛏正丁醇部分对脾淋巴细胞的增殖率为500%,少数提取成分对免疫细胞的增殖具有抑制作用。[结论]真瓣鳃目5种海洋贝类提取物大多对肿瘤细胞的生长有一定的抑制作用,且对小鼠脾淋巴细胞的增殖也有较强的调节作用。     

旋覆花活性成分研究进展

旋覆花含有多种生物活性成分,本文就其所含的黄酮类和糖类的药理活性、提取和分离方法、结构类型做一综述。     

大豆蛋白的小分子酶解产物抗氧化活性研究

以低温冷轧豆粕为原料、大豆分离蛋白为反应底物,进行酶水解反应,酶解产物经离子交换层析,凝胶排阻层析等方法分离,获得了平均分子量为800 D的小分子活性肽(SBP),用邻苯三酚自氧化法测定其抗氧化性。结果表明:此类小分子活性肽对邻苯三酚(PR)自氧化具有较好的抑制作用(1 mg/mL SBP的抑制率为33.3%)。与谷胱甘肽(GSH)进行比较,二者具有相似的抗氧化活性。     

血散薯块根内生真菌Periconia igniaria Stdif10发酵产物的生物活性研究

Periconia igniaria Stdif10是从血散薯块根中首次分离得到的内生真菌,为了解该内生真菌的生物学活性,采用滤纸药膜法、菌丝生长速率法和带药培养基涂布法分别测定了该菌发酵产物不同溶剂萃取物的抗虫活性、抗真菌活性、抗细菌活性。结果表明,发酵产物的石油醚萃取物表现出较好的抗虫和抗菌活性。其中,对玉米象具有显著的触杀活性,处理72 h的LC_(50)值为2.295 1 mg/cm~2。石油醚萃取物对玉米象还具有较好的驱避活性,处理48 h后在3.932、7.863、15.726 mg/cm~2 3个浓度梯度下对玉米象的驱避率均大于62%。石油醚萃取物对辣椒炭疽病菌、水稻胡麻叶病菌、茶轮斑病菌、甘蓝黑斑病菌、甘蔗凤梨病菌、烟草黑胫病菌、玉米大斑病菌、金橘砂皮病菌、贡柑链格孢菌9种供试植物病原真菌具有不同程度的抑制作用,其中对辣椒炭疽病菌、烟草黑胫病菌、金橘砂皮病菌3种病原真菌具有较好的抗菌活性,处理72 h的EC_(50)值分别为0.117 3、0.071 6、0.054 7 mg/mL。石油醚萃取物对产气肠杆菌、铜绿假单孢菌、大肠杆菌、普通变形杆菌、伤寒沙门氏菌、金黄色葡萄球菌、蜡样芽孢杆菌、巨大芽孢杆菌、枯草芽孢杆菌、炭疽杆菌10种动物病原细菌具有显著的抗菌活性,处理24 h的MIC值为0.125～0.500 mg/mL。上述结果表明,血散薯内生真菌Periconia igniaria Stdif10次生代谢产物具有显著的抗虫和广谱的抗菌活性,且石油醚萃取物活性最佳(活性物质极性较低)。     

辫根七杀虫活性研究

以辫根七为原料,经过回流提取、系统溶剂萃取,采用小叶碟添加法对各供试样品进行检测.结果表明：辫根七中极性成分和非极性成分均有较强的生物活性,但以极性成分稍强.杀虫活性物质主要是生物碱.经柱层析获得5种物质,有2种物质对3龄粘虫具有较高的拒食活性,1种物质对粘虫具有诱食活性.这种既具有高拒食活性成分,又含有诱食活性成分的物质尚不多见.     

Coherent optical control of the quantum state of a single quantum Dot

Picosecond optical excitation was used to coherently control the excitation in a single quantum dot on a time scale that is short compared with the time scale for loss of quantum coherence. The excitonic wave function was manipulated by controlling the optical phase of the two-pulse sequence through timing and polarization. Wave function engineering techniques, developed in atomic and molecular systems, were used to monitor and control a nonstationary quantum mechanical state composed of a superposition of eigenstates. The results extend the concept of coherent control in semiconductors to the limit of a single quantum system in a zero-dimensional quantum dot.     

Controlled phase shifts with a single quantum dot

Optical nonlinearities enable photon-photon interaction and lie at the heart of several proposals for quantum information processing, quantum nondemolition measurements of photons, and optical signal processing. To date, the largest nonlinearities have been realized with single atoms and atomic ensembles. We show that a single quantum dot coupled to a photonic crystal nanocavity can facilitate controlled phase and amplitude modulation between two modes of light at the single-photon level. At larger control powers, we observed phase shifts up to pi/4 and amplitude modulation up to 50%. This was accomplished by varying the photon number in the control beam at a wavelength that was the same as that of the signal, or at a wavelength that was detuned by several quantum dot linewidths from the signal. Our results present a step toward quantum logic devices and quantum nondemolition measurements on a chip.     

Quantum coherence in an optical modulator

Semiconductor quantum well electroabsorption modulators are widely used to modulate near-infrared (NIR) radiation at frequencies below 0.1 terahertz (THz). Here, the NIR absorption of undoped quantum wells was modulated by strong electric fields with frequencies between 1.5 and 3.9 THz. The THz field coupled two excited states (excitons) of the quantum wells, as manifested by a new THz frequency- and power-dependent NIR absorption line. Nonperturbative theory and experiment indicate that the THz field generated a coherent quantum superposition of an absorbing and a nonabsorbing exciton. This quantum coherence may yield new applications for quantum well modulators in optical communications.     

Optical gain and stimulated emission in nanocrystal quantum dots

The development of optical gain in chemically synthesized semiconductor nanoparticles (nanocrystal quantum dots) has been intensely studied as the first step toward nanocrystal quantum dot lasers. We examined the competing dynamical processes involved in optical amplification and lasing in nanocrystal quantum dots and found that, despite a highly efficient intrinsic nonradiative Auger recombination, large optical gain can be developed at the wavelength of the emitting transition for close-packed solids of these dots. Narrowband stimulated emission with a pronounced gain threshold at wavelengths tunable with the size of the nanocrystal was observed, as expected from quantum confinement effects. These results unambiguously demonstrate the feasibility of nanocrystal quantum dot lasers.     

Quantum spin hall insulator state in HgTe quantum wells

Recent theory predicted that the quantum spin Hall effect, a fundamentally new quantum state of matter that exists at zero external magnetic field, may be realized in HgTe/(Hg,Cd)Te quantum wells. We fabricated such sample structures with low density and high mobility in which we could tune, through an external gate voltage, the carrier conduction from n-type to p-type, passing through an insulating regime. For thin quantum wells with well width d < 6.3 nanometers, the insulating regime showed the conventional behavior of vanishingly small conductance at low temperature. However, for thicker quantum wells (d > 6.3 nanometers), the nominally insulating regime showed a plateau of residual conductance close to 2e(2)/h, where e is the electron charge and h is Planck's constant. The residual conductance was independent of the sample width, indicating that it is caused by edge states. Furthermore, the residual conductance was destroyed by a small external magnetic field. The quantum phase transition at the critical thickness, d = 6.3 nanometers, was also independently determined from the magnetic field-induced insulator-to-metal transition. These observations provide experimental evidence of the quantum spin Hall effect.     

Quantum phase transition of a magnet in a spin bath

The excitation spectrum of a model magnetic system, LiHoF4, was studied with the use of neutron spectroscopy as the system was tuned to its quantum critical point by an applied magnetic field. The electronic mode softening expected for a quantum phase transition was forestalled by hyperfine coupling to the nuclear spins. We found that interactions with the nuclear spin bath controlled the length scale over which the excitations could be entangled. This generic result places a limit on our ability to observe intrinsic electronic quantum criticality.     

论耕地总量动态平衡及其实施的技术基础

从土地管理的目标出发,分析了耕地总量动态平衡的实质,提出了耕地总量动态平衡的内涵及其函数模型,进而分析了耕地数量、耕地质量、时代（时间）和区域（空间）等四个变量因素与耕地总量动态平衡的相关性,并认为制定一个科学的、切实可行的土地利用总体规划是实施耕地总量动态平衡的技术基础．     

Time-resolved measurement of dissipation-induced decoherence in a Josephson junction

We determined the dissipation-induced decoherence time (DIDT) of a superconducting Josephson tunnel junction by time-resolved measurements of its escape dynamics. Double-exponential behavior of the time-dependent escape probability was observed, suggesting the occurrence of a two-level decay-tunneling process in which energy relaxation from the excited to the ground level significantly affects the escape dynamics of the system. The observation of temporal double-exponential dependence enables direct measurements of the DIDT, a property critical to the study of quantum dynamics and the realization of macroscopic quantum coherence and quantum computing. We found that the DIDT was tau(d) > 11 micros at T = 0.55 K, demonstrating good prospects for implementing quantum computing with Josephson devices.     

Implementing the quantum von Neumann architecture with superconducting circuits

The von Neumann architecture for a classical computer comprises a central processing unit and a memory holding instructions and data. We demonstrate a quantum central processing unit that exchanges data with a quantum random-access memory integrated on a chip, with instructions stored on a classical computer. We test our quantum machine by executing codes that involve seven quantum elements: Two superconducting qubits coupled through a quantum bus, two quantum memories, and two zeroing registers. Two vital algorithms for quantum computing are demonstrated, the quantum Fourier transform, with 66% process fidelity, and the three-qubit Toffoli-class OR phase gate, with 98% phase fidelity. Our results, in combination especially with longer qubit coherence, illustrate a potentially viable approach to factoring numbers and implementing simple quantum error correction codes.     

Quantum communication with zero-capacity channels

Communication over a noisy quantum channel introduces errors in the transmission that must be corrected. A fundamental bound on quantum error correction is the quantum capacity, which quantifies the amount of quantum data that can be protected. We show theoretically that two quantum channels, each with a transmission capacity of zero, can have a nonzero capacity when used together. This unveils a rich structure in the theory of quantum communications, implying that the quantum capacity does not completely specify a channel's ability to transmit quantum information.