家禽动眼神经副交感核和Cajal中介核至脊髓的直接投射——HRP法研究

采用微电泳导入法和微量注射法,将HRP分别引入脊髓的颈中部、颈膨大部和腰膨大部,逆行追踪了北京鸭、麻鸭、鹅、鸡、鸽子和鹌鹑6种家禽的上位神经元。结果发现：大量标记细胞不仅分布于中脑对侧红核,还分布于双侧的动眼神经副交感核（EW核）,Cajal中介核和中央灰质,少量标记细胞分布于中脑网状结构和中缝核。标记细胞分布数量的规律是：颈中部引入HRP后,出现的标记细胞最多;颈膨大部引入HRP者次之;腰膨大部引入HRP后,出现的标记细胞最少。两种方法的实验结果没有明显的差异。6种动物之间的差异也不显著。各组实验中,在中脑的顶盖没有任何部位出现标记细胞。研究结果表明：家禽的中脑脊髓通路中,除了具有红核脊髓束、网状脊髓束和中缝脊髓束外,还存在着EW核至脊髓的直接传导通路和Cajal中介核至脊髓的直接传导通路。     

小麦条锈菌夏孢子和芽管细胞核荧光染色技术

用荧光染料DAPI研究结果表明,小麦条锈菌夏孢子染核的最适浓度为5μg/mL,染色时间为3min;夏孢子芽管染核的适宜浓度为3μg/mL,染色时间为2～3min。本研究还发现DAPI对分属于5个亚门中的30种植物病原真菌的孢子(孢子囊)、芽管和菌丝同样具有较好的染核效果。     

Ocean Water as a Source of Ice Nuclei

Preliminary tests indicate that ocean water may release an abundance of ice nuclei to the atmosphere. These results may explain the observation that marked anomalies often accompany an influx of marine air in the Washington, D. C., area and the fact that abnormal counts are often associated with widespread precipitation.     

鲫鱼肝组织细胞核电镜图像三维重建的研究

[目的]将电镜三维重建技术引进到水产学和水生生物学研究领域。[方法]利用连续超薄切片电子显微镜技术对正常状态下鲫鱼肝组织细胞核超微结构的进行观察和连续拍照,并利用计算机三维重建技术对连续拍照的图片进行三维重建。[结果]使用Recon—struct软件,成功地对基于连续超薄切片的鲫鱼肝细胞核电镜图像进行了三维重建。[结论]使用电镜三维重建技术进行细胞超微结构的三维重建是可行的。     

形变及其对丰质子核23Al性质的影响

采用同位旋依赖的尼尔逊势, 在宏观微观模型的理论框架下, 计算考察了N＝10同中子链和Z＝13同位素链上原子核的结构和性质. 重点考察了23Al 的核结构. 理论计算很好的给出了这些原子核的解核能和形变, 讨论了23Al 基态的自旋和宇称, 结果表明形变对于理解23Al 的结构和性质非常重要. 此外, 还讨论了轻核区可的晕结构和能级反转.     

Isospin in Nuclei: Isospin has been reborn as an important and useful quantum number for all nuclei

The major feature of isospin in nuclei that I have discussed here is its application to all nuclei. The rebirth of this quantum number in nuclear physics occurred in the early 1960's and was initiated almost entirely by the important work of Anderson et al. (4) and Fox et al. (5). There is still great interest in the use of isospin in its fullest sense as predicted by Wigner (3), and indeed isospin concepts have been largely responsible for demonstrating that nuclei in the doubly "magic number" region of (208)Pb are remarkably in agreement with shell model theory. The early experiments have also initiated a whole new set of more sophisticated experiments (some of which I have briefly alluded to above) which promise to keep many physicists busy for a long time to come. A particularly interesting series of experiments are those being performed (15) at Duke University with high-resolution proton beams. This work shows the highly detailed nature of analogue resonances, that is, as coherent superpositions of many complicated compound states yielding a beautifully modulated wave train, the modulation being observed only in conventional experiments with poor-resolution proton beams. Similarly, nuclear theorists have been led to vastly improve their interpretation of, and computational techniques for, both nuclear reactions and nuclear structure in order to meet the more stringent tests provided by such experiments. Perhaps a lesson can be learned from the historical development of the isospin concept. In the past the belief that T . T would not significantly commute with the dynamical Hamiltonian so that isospin would not be conserved sufficiently well enough certainly delayed the nuclear travels of isospin into the realm of heavy nuclei. Hopefully the same mistake will not occur in the future for other approximate symmetries of nature.     

Incorporation of Tritiated Thymidine into Nuclei of Shoot Apical Meristems

Tritiated thymidine enters readily into certain excised plant parts and into small aquatic plants. Attempts to introduce the radioisotope into shoot tips of seed plants via the roots have not proved satisfactory. The label readily enters the shoot if applied directly to immature leaves of a bud after the application of a wetting agent.     

小麦叶内锈菌细胞核荧光染色方法

本文对小麦叶内锈菌菌丝细胞核的荧光染色方法进行了研究。受锈菌侵染的小麦叶片经0.25％纤维素酶和0.12％Driselase混合液培养2～3h,锈菌菌落从组织中游离出。菌落经荧光染料DAPI(5μg/mL)和Calcoflour white(0.001％)分别染色1～3min后,菌丝的细胞核、壁、隔膜在荧光显微镜下易于观察辩认。     

用1／N展开技术研究汞核的能谱和B(E2)

用１／Ｎ展开法加上自洽Ｑ框架的ｓｄＩＢＭ１研究比Ｈｆ更重一些的中等质量核的Ｈｇ的同位素的能谱,计算了＾１８６Ｈｇ基带的几个Ｂ（Ｅ２）值,有一定程度的符合,高激发态符合得较好,特别是能正确反映出Ｂ（Ｅ２）值随能级谱化的趋势,而且只用了很少的可调参数去拟合大量数据,注意到值随能级变化的趋势,而且只用了很少的可调参数去拟合大量数据。注意到Ｈｇ核的质子数Ｚ＝８０,很接满壳层,可见１／Ｎ展开展理论适用于很大     

稳定核素范围整数规律和上界核坐标为44的论证

在引入两新参量S和H的核素图中，由稳定核边界分布规律的分析得到：偶Z界核对应区的Z下界核坐标增量ΔS的8，4，2递变，以及坐标差K为偶常数12－－8的偶偶核上界核和偶Z52－80的下界核的坐标增量ΔH的8，8，4，4，2，2递变，并由此推出，稳定区的两坐标上限都应该是44。     

乳牛精子细胞核可被精确地分成类似于X,Y精子的两个群体

由于哺乳动物雄性配子(精子)有性染色体的差异,使哺乳动物X、Y精子在质量或密度上存在着微小的差别。因此,长期以来人们试图将两性精子分开,以人的意志控制动物性别,按人类的需要进行畜牧业生产。但是由于精于之间发育上的差异所引起的质量差掩盖了染色质的微弱差异,从而难以达到理想的分离效果。本实验先将两性精子共有的顶体和尾部去掉,以突出X、Y染色质的质量差异,再将精子细胞核在氯化铯密度梯度离心下分成两个核群区带。该实验为X、Y精于分离效果的鉴定提供了一种有效的方法。     

小麦条锈菌夏孢子芽管核染色方法的改进研究

海登汉氏苏木精法也称铁矶苏木精法,是常用的真菌细胞核染色方法,R.Litt-le & J.G.Manners(1969)曾报导用此法可对小麦条锈菌夏孢子芽管核进行染色,但 R.B.Volin(1971);井金学、商洪生(1980);李振岐、E.L.Sharp 和 M.Rein-hold(1983)在对小麦条锈菌夏孢子芽管核的染色试验中均发现用此法染核难以掌握。为此,李振岐和 E.L.Sharp 等于1983年3—4月结合小麦条绣菌异核作用研究需要对     

The underclass: definition and measurement

The term "underclass" has been widely used by journalists and by some social scientists but, until recently, has not been clearly defined or quantified. Most of the recent quantitatively oriented literature on the topic has used a definition that emphasizes either the persistence ofpoverty or the number ofpeople living in neighborhoods where the incidence ofpoverty or dysfunctional behavior is high. Conclusions about the size and growth of the underclass are sensitive to the definition chosen, but most available evidence suggests that it is small but growing.     

The greenhouse effect: science and policy

Global warming from the increase in greenhouse gases has become a major scientific and political issue during the past decade. That infrared radiation is trapped by greenhouse gases and particles in a planetary atmosphere and that the atmospheric CO(2) level has increased by some 25 percent since 1850 because of fossil fuel combustion and land use (largely deforestation) are not controversial; levels of other trace greenhouse gases such as methane and chlorofluorocarbons have increased by even larger factors. Estimates of present and future effects, however, have significant uncertainties. There have also recently been controversial claims that a global warming signal has been detected. Results from most recent climatic models suggest that global average surface temperatures will increase by some 2 degrees to 6 degrees C during the next century, but future changes in greenhouse gas concentrations and feedback processes not properly accounted for in the models could produce greater or smaller increases. Sea level rises of 0.5 to 1.5 meters are typically projected for the next century, but there is a small probability of greater or even negative change. Forecasts of the distribution of variables such as soil moisture or precipitation patterns have even greater uncertainties. Policy responses range from engineering countermeasures to passive adaptation to prevention and a "law of the atmosphere." One approach is to implement those policies now that will reduce emissions of greenhouse gases and have additional societal benefits. Whether the uncertainties are large enough to suggest delaying policy responses is not a scientific question per se, but a value judgment.     

The last interglacial: paleotemperatures and chronology

The O(18)/O(16) analysis and Th(230)/Pa(231) dating of deep-sea cores showed that the last interglacial age, with an early major temperature maximum followed by two smaller ones, extended from 100,000 to 70,000 years ago and was preceded by a glacial age extending from 120,000 to 100,000 years ago. The O(18)/O(16) analysis and Th(230)/U(234) dating of speleothems confirm and refine these ages.