生长调节物质对春石斛假鳞茎萌芽与封顶的调控效应

该文在探讨春石斛假鳞茎生长规律基础上,研究了GA3和6-BA对高芽萌发的调控效果,PP333对假鳞茎封顶的调控效果。结果表明:生长季,假鳞茎节间平均生长长度为3。57 cm,节间日均生长量为0.068 cm,假鳞茎日均生长量为0.28 cm;如需形成50～60 cm高的假鳞茎,需要在1月末至2月间开始留鳞芽, 同时需要不能晚于8月底停长,假鳞茎节数可达14～19节,能形成高质量的假鳞茎;PP333可促进假鳞茎及时封顶,50 mg/L灌根处理效果最佳;用6-BA处理有利于高芽和鳞芽形成, 植株灌根浓度以200 mg/L最佳;GA3各种浓度处理都不利于高芽和鳞芽形成,导致徒长和落叶。      

纯镁粉末坯往复挤-镦的数值模拟及实验研究

采用DEFORM-2D有限元软件对纯镁粉末多道次往复挤-镦块体机械冶金过程进行有限元模拟,分析了往复挤-镦过程中的流场、应力场及应变场等相关场量变化规律.模拟结果表明：挤压段材料纵向流动,镦粗段材料横向流动,流速和流向的不一致形成强烈的交替剪切效应,且试样的主变形区域处于三向压应力状态.试样的等效应变呈不均匀分布,但应变的均匀性随着往复挤-镦道次的增加而有所改善.3道次往复挤-镦实验结果表明：试样产生显著的条带状组织,主变形区强烈的剪切力将原镁粉表面的氧化物和其内部的孔隙破碎,形成强烈的致密效应,相对密度接近0.98,组织上达到了良好的冶金结合.     

Oscillation of cyclic adenosine monophosphate concentration during the myocardial contraction cycle

The concentration of adenosine 3',5'-monophosphate (cyclic AMP) rises and falls during each myocardial contraction cycle. Peak concentrations of cyclic AMP precede peak development of systolic tension. Epinephrine alters the normal oscillation in myocardial cyclic AMP and increases both diastolic and systolic concentrations of the cyclic nucleotide. These transient changes in myocardial cyclic AMP indicate a potential role for cyclic AMP as a beat-to-beat regulator of myocardial contractility.     

Thyroid-stimulating hormone and prostaglandin E1 stimulation of cyclic 3',5'-adenosine monophosphate in thyroid slices

Thyroid-stimulating hormone increased the cyclic 3',5'-adenosine monophosphate concentration in dog thyroid slices during a 1-minute incubation period and produced a maximum effect soon thereafter. The elevation persisted for at least 30 minutes. The concentrations of the cyclic 3',5'-adenosine monophosphate increased as the TSH concentration was increased from 0.125 to 50 milliunits per milliliter. Prostaglandin E(1), which increases glucose oxidation in dog thyroid slices, also increased the concentration of cyclic 3',5'-adenosine monophosphate. Although sodium fluoride stimulates thyroid adenyl cyclase, it did not increase concentration of cyclic 3',5'-adenosine monophosphate. Carbamylcholine and menadiol sodium diphosphate augment glucose oxidation in dog thyroid slices but do not change concentrations of cyclic 3',5'-adenosine monophosphate.     

Cyclic nucleotide phosphodiesterase: high activity in a mammalian photoreceptor

Purified outer segments of bovine rods exhibit phosphodiesterase activity against adenosine and guanosine cyclic 3',5'-monophosphates (cyclic AMP and cyclic GMP). The enzyme hydrolyzed cyclic GMP more rapidly than cyclic AMP at low substrate concentrations. The presence of high phosphodiesterase activity in this highly specialized organelle suggests that this enzyme may function in control of cyclic nucleotide concentration during visual excitation or adaptation.     

Cyclic adenosine monophosphate and norepinephrine: effects on transmembrane properties of cerebellar Purkinje cells

Electrical properties of Purkinje cells were recorded by intracellular microelectrode during extracellular electrophoretic application of gamma aminobutyrate, norepinephrine, cyclic adenosine monophosphate, and dibutyryl cyclic adenosine monophosphate. All these substances hyperpolarized Purkinje cells. Transmembrane resistance decreased during gamma aminobutyrate hyperpolarization. In contrast, norepinephrine and the cyclic nucleotides generally elevated resistance. These results show that cyclic nucleotides mimic the unique effects of norepinephrine on the bioelectric properties of neuronal membranes.     

Fatigue failure in polysilicon not due to simple stress corrosion cracking

In the absence of a corrosive environment, brittle materials such as silicon should be immune to cyclic fatigue. However, fatigue effects are well known in micrometer-sized polycrystalline silicon (polysilicon) samples tested in air. To investigate the origins of this phenomenon in polysilicon, we developed a fixed-grip fracture mechanics microspecimen but could find no evidence of static stress corrosion cracking. The environmental sensitivity of the fatigue resistance was also investigated under cyclic loading. For low-cycle fatigue, the behavior is independent of the ambient conditions, whether air or vacuum, but is strongly influenced by the ratio of compressive to tensile stresses experienced during each cycle. The fatigue damage most likely originates from contact stresses at processing-related surface asperities; subcritical crack growth then ensues during further cyclic loading. The lower far-field stresses involved in high-cycle fatigue induce reduced levels of fatigue damage. Under these conditions, a corrosive ambient such as laboratory air exacerbates the fatigue process. Without cyclic loading, polysilicon does not undergo stress corrosion cracking.     

Phosphodiesterase in Dictyostelium discoideum and the chemotactic response to cyclic adenosine monophosphate

A phosphodiesterase with a low Michaelis constant for cyclic adenosine monophosphate was found in the membrane fraction of the cellular slime mold. This activity was highest during the aggregation stage. Enzyme with similar properties was also secreted by the cells. Dithiothreitol inhibited both enzymes and potentiated the cellular response to cyclic adenosine monophosphate.     

钼肥对苋菜生长及品质、产量的影响

试验采用0.67、1.00、2.00 mL/L的钼肥对苋菜(Amaranthus mangostanus L.)进行叶面喷施,研究钼肥对苋菜生长及品质的影响.结果表明,适宜浓度的钼肥可促进苋菜的生长,提高叶绿素含量,增加产量,改善品质,并降低叶片硝酸盐的累积.但在不同的生长发育期,其作用效应有所不同.以1.00 mL/L的钼肥处理效果较好.     

低聚木糖对仔猪生产性能和肠道菌群的影响

研究低聚木糖(XOS)对仔猪生长性能及对断奶仔猪肠道菌群的影响.选用杜×长×大三元杂交仔猪166头,随机分成3组,每组5个重复,于7日龄诱食后饲喂添加XOS和抗生素的饲料,以观察对仔猪生长性能和断奶仔猪肠道菌群的影响.结果表明:饲喂XOS能显著提高哺乳仔猪的生长性能,且在29～40日龄显著高于抗生素组(P<0.05);断奶前后XOS组乳酸菌的含量显著高于抗生素组和对照组,大肠杆菌数量差异不显著.     

Compartmentalization of cyclic AMP during phagocytosis by human neutrophilic granulocytes

Immunocytochemistry shows that early during phagocytosis of zymosan, adenosine 3',5'-monophosphate (cyclic AMP) appears on the cell surface before the phagosome is internalized. The appearance of cyclic AMP on the cell surface is coincident with that of granule products and regulatory subunit of type I cyclic AMP-dependent protein kinase. Guanosine 3',5'-monophosphate is not associated with the initiation site of phagocytosis, but is observed throughout the granular cytoplasmic region. This sharply localized accumulation of cyclic AMP may serve as a signal for the initiation of phagocytosis.     

Growth and transparency in the lens, an epithelial tissue, stimulated by pulses of PDGF

The rat lens undergoes dramatic growth during early postnatal development. Lens weight increased by a factor of 23 in 26 days. Growth rate per day oscillated between 0 and 87 percent. A new culture system was designed to study the oscillations in growth during development. Lens growth and transparency in vitro required pulsatile delivery of platelet-derived growth factor (PDGF) in HL-1 serum-free medium. Continuous delivery of HL-1 medium with PDGF or pulsatile delivery of HL-1 medium without PDGF resulted in lens opacity and no growth. These results provide direct evidence that PDGF stimulates an epithelial tissue and that oscillations in growth occur during normal development of the rat lens.     

神经生长因子NGF及其受体TrkA在雌性水牛生殖器官的表达定位

为研究神经生长因子NGF及其受体TrkA在广西雌性水牛生殖器官中表达定位情况,运用免疫组织化学ABC法对处于发情周期不同阶段(卵泡期、黄体期)成年水牛的卵巢、子宫、输卵管NGF、TrkA分别进行染色定位.结果表明:NGF/TrkA阳性细胞在卵巢主要见于卵泡内膜细胞、颗粒细胞及黄体细胞;在子宫主要见于子宫内膜上皮细胞、腺...     

Hormonal control of neutrophil lysosomal enzyme release: effect of epinephrine on adenosine 3',5'-monophosphate

Human neutrophilic leukocytes release neutral protease and beta-glucuronidase during cell contact with, and phagocytosis of, zymosan particles treated with rheumatoid arthritic serum. Release of lysosomal enzymes is inhibited by epinephrine and adenosine 3',5'-monophosphate (cyclic AMP), but not by phenylephrine or adenosine 5'-monophosphate. Inhibition of enzyme release by epinephrine may be mediated by cyclic AMP because the cyclic AMP in the neutrophils is increased by epinephrine treatment at the time when enzyme release is reduced.     

青海云杉撒播育苗技术

在互助李丰苗圃对青海云杉进行了撒播育苗实验,结果表明,青海云杉的撒播育苗操作技术简单,可以充分利用土地资源,在青海云杉苗木培育过程中可以考虑撒播育苗技术。     

不同苗种来源香港牡蛎的生长差异及基因表达相关分析

【目的】明确不同苗种来源香港牡蛎的生长差异及生长相关基因表达模式,为筛选出生长性状候选基因打下理论基础,也为繁育优质香港牡蛎新品种提供参考依据。【方法】通过比较人工繁育（人工组）和自然海域半人工采苗（天然组）2种模式获得香港牡蛎的生长差异,利用实时荧光定量PCR检测不同苗种来源香港牡蛎外套膜和闭壳肌中IGF1、AMPKα和FoxO1基因的表达情况,并利用统计学方法及相关分析探究生长指标（壳高、壳长、壳宽、鲜重和软体重）与生长相关基因表达变化间的相关性。【结果】人工组和天然组香港牡蛎在试验期间（4月龄～12月龄）的壳高、壳长、壳宽、鲜重和软体重等生长指标整体上呈增长趋势;人工组香港牡蛎的生长指标均显著高于天然组香港牡蛎（P<0.05,下同）,但天然组香港牡蛎生长指标的整体增幅高于人工组香港牡蛎。天然组香港牡蛎外套膜和闭壳肌中IGF1、AMPKα和FoxO1基因在不同发育阶段的相对表达量整体上高于人工组香港牡蛎,但差异均不显著（P>0.05,下同）。相关分析结果表明,人工组和天然组香港牡蛎生长相关基因表达与生长性状间具有相关性,其中外套膜和闭壳肌的IGF1基因表达总量与壳高呈负...     

鲜枣贮藏及酒制过程中营养成份的变化

在室温条件下ｃＡＭＰ和ｃＧＭＰ含量均在贮后８ｄ左右出现１个波谷，而ｃＡＭＰ／ｃＧＭＰ值在整个贮藏过程中（２４ｄ）一直呈上升趋势；在１０℃和－２５℃条件下，贮后前１６ｄｃＡＭＰ和ｃＧＭＰ含量均有所上升，之后ｃＡＭＰ含量趋于稳定，而ｃＧＭＰ含量逐渐下降，ｃＡＭＰ／ｃＧＭＰ值分别在贮后８ｄ和１６ｄ各出现１个小波谷，但整体上呈上升趋势。鲜枣酒制过程中Ｖｃ含量迅速下降，１５ｄ后仅剩下３．０～３．３％；总糖含量和糖酸比呈持续下降趋势，尤以前期下降较为迅速；还原糖和可滴定酸含量在酒制初期有较大幅度上升，后期因品种不同而异。     

生长调节剂促进3种球根花卉开花的研究

生长调节剂（A1，A2）能有效地促进郁金香花芽分化，A1效果比A2显著，经A1处理后，开花率比对照提高40％，花茎长度增加11cm，花期提早10d，寿命延长4d。生长调节剂（B1，B2）可促进彩色蹄莲开花，B2的效果优于B1，开花率比对照提高52％，花茎长度增加18cm，花杂直径增加1.4cm，同时有效地克服了花畸形现象，生长调节剂（C1，C2）能明显改善唐菖蒲切花品质，C2处理较对照的单株平均花数增加5杂，种球围径增加3.8cm。     

Identity of HeLa cell determinants acquired by vesicular stomatitis virus with a tumor antigen

Growth of vesicular stomatitis virus (VSV) in HeLa cells results in progeny containing non-VSV antigens with a molecular weight around 75,000. The non-VSV antigens were detected by antiserums to HeLa cell determinants. These antiserums precipitate whole virions but do not neutralize them. Because one of the antiserums is directed to a tumor-specific surface antigen of HeLa cells, it appears that VSV specifically acquires such antigens during its passage through human tumor cells.     

Neurosecretory cells: daily rhythmicity in Leiobunum longipes

A fluorometric-analysis procedure, used to quantitate indoles, confirmed the presence of 5-hydroxytryptamine (5-HT) in an arachnid; there was unimodal cyclic production of 5-HT in brain and intestinal tissues over a 24-hour period. The same tissues produced 5-HT after 80-day culture; bimodal cyclic output was indicated during continuous 24-hour study. One peak occurred at 0200 hours, at the same time as the peak in vivo, suggesting an endogenously controlled mechanism of secretion. The second peak occurred at midmorning, a time when production in vivo was lowest, suggesting that there is a possible feedback-control mechanism in the organism that inhibits the endogenous output of 5-HT.