药材鳖甲的真伪鉴别

中药鳖甲是使用鳖的背甲。近来发现有以腹甲混入背甲充作药用。本文从鳖的背甲及腹甲形态特征进行比较,这样就改进了鳖甲的鉴别方法。     

温敏无核荔枝的种子败育和果实发育研究

运用胚胎学、解剖学的方法 ,对海南新发现的温敏无核荔枝产生无核果实的原因进行研究 .结果表明 :温敏无核荔枝由于低温影响 ,在受精过程中 ,精子不能进入卵膜或进入卵后雌雄核不融合 ,导致卵受精失败并退化 .次生核虽正常受精 ,并产生核型胚乳 ,有的还能发育到细胞型胚 ,到 12d左右也完全退化 .结果导致胚珠极早败育 ,但假种皮仍能发生发育 ,最终形成无核果实     

化学药剂诱导矮败小麦子房发育的生化分析

在大田条件下 ,采用正常授粉 ,同时在隔离区条件下 ,用化学药剂 (1号液 :5 0 0mg·kg-1对氯苯氧乙酸+10 0mg·kg-1激动素 +体积分数为 0 .0 15二甲基亚砜 ,2号液 :5 0 0mg·kg-1对氯苯氧乙酸 +10 0mg·kg-1激动素 +体积分数为 0 .0 15二甲基亚砜 +10 0mg·kg-1赤霉素 )分别处理矮败小麦的子房 ,并以蒸馏水处理为对照。取材后进行生化分析。结果表明 :(1)正常授粉的子房 ,蛋白质含量、氨基酸含量、葡萄糖含量、蔗糖转化酶活性、谷丙转氨酶活性、过氧化物酶活性和呼吸强度都随着子房的发育逐渐升高。 (2 )化学药剂处理和对照处理的子房 ,发育初期上述生化指标明显升高 ,但发育后期随着子房的退化 ,上述生化指标又明显下降     

Evolution and ecological correlates of uniparental reproduction in freshwater snails

We review the spatial and temporal correlates of uniparental reproduction in freshwater snails as they pertain to the ecological hypotheses for the maintenance of biparental sex. The biogeographic evidence from two species (Potamopyrgus antipodarum andBulinus truncatus) presently supports the Red Queen hypothesis that biparental reproduction is selected as a way to reduce the risk to progeny of parasite attack. Uniparental reproduction in these species is associated with low levels of infection by parasites (castrating digenetic trematodes), suggesting that parthenogenesis or self-fertilization can replace cross-fertilization when the risk of infection is low. In addition, inB. truncatus, the opportunity for cross-fertilization coincides with the season in which parasite attack is highest. In a third species (Campeloma decisum), parthenogenetic reproduction is correlated with latitude and the presence of a non-castrating trematode that may prevent cross-fertilization; these patterns suggest that parthenogenesis has been selected as a mechanism to assure reproduction. Finally, we discuss the spotty taxonomic distribution of parthenogenetic species.     

Strategies for the design of inhibitors of aldose reductase, an enzyme showing pronounced induced-fit adaptations

Aldose reductase is involved in the polyol pathway, catalyzing the reduction of glucose to sorbitol. However, due to pronounced binding site adaptations, the enzyme can operate on a broad palette of structurally diverse substrates ranging from small aliphatic and aromatic aldehydes up to steroid-type ligands. A comparative analysis of the presently accessible crystal structures of aldose reductase complexes reveals four binding-competent protein conformations. Additional relevant conformers are detected through molecular dynamics simulations. They indicate an equilibrium of several conformers which is shifted towards the binding-competent geometries upon ligand binding. Such a manifold system with several alternative binding site conformers requires some tailored concepts in virtual screening. We followed two strategies, both successfully suggesting new micromolar inhibitors. In a first attempt, we concentrated on one preferred conformer and performed a virtual screening, assuming that the binding pocket of aldose reductase adopts only this conformation. In a second approach, we followed a ligand superpositioning method. Ligands were extracted in their bound conformations from three different crystal structures, all accommodating the ligands with different active site conformations. After merging these ligands into one supermolecule, mutual alignments were computed, taking candidate ligands from a screening database. The latter strategy also retrieved several structurally new inhibitors of micromolar potency.     

联合用药终止中期妊娠临床研究

目的：探讨米非司酮及米索前列醇与利凡诺配伍使用终止中期妊娠的可行性。方法：采用口服米非司酮及米索前列醇，配伍经腹羊膜腔内注射利凡诺终止中期妊娠，对其结果进行统计学分析。结果：联合用药注药至胎儿胎盘排出时间21-26.67h，成功率98.7%，与对照组比较有显著性差异。结论：米非司酮及米索前列醇与利凡诺配伍使用终止中期妊娠引产具有较好的临床效果和可行性。     

水稻雄性不育细胞组织学的研究

水稻雄性不育系的花粉败育一般可分为无花粉型、单核败育型、双核败育型和三核败育型等四种。个别不育系花粉败育方式较特殊。野败不育系的花丝和药隔维管束退化最严重,花药开裂结构的异常主要表现在裂口、裂腔分化发育异常。     

肿瘤侵袭和转移的规律及其药物防治策略

介绍了肿瘤侵袭和转移的规律及药物防治策略，提出了阻断肿瘤侵袭，转移过程的各个步骤是今后的研究方向。     

关于占线广播调度问题的一个下界

通过研究带有时限的占线广播调度问题及其贪婪算法竞争比为5、确定性算法的竞争比下界为2.59,来剖析所有请求均为紧时限的特殊情形,并运用最坏情形分析法分析得出,在任意一个连续中断的序列中最大中断比具有逐渐减小的变化特征,进而证明了在所有可能的两类连续中断序列中都不可能存在竞争比小于4的确定性算法.由此得出,当请求均为紧时限时,竞争比下界为4.由于紧时限是任意时限的一个特例,从而得出请求为任意时限时的竞争比下界至少为4的结论.     

In vitro study of poly(ethylene carbonate) as a drug-eluting stent coating

An in vitro feasibility study of the use of poly(ethylene carbonate) (PEC) as a biodegradable coating material for drug-eluting stents is reported, and the performance of PEC is compared with that of poly(lactic-co-glycolic acid) (PLGA). Scanning electron microscopy (SEM) images of PEC and PLGA discs after treatment with an alkaline KO2 solution as a superoxide source showed that the PEC maintained its integrity whereas holes and small particles appeared during the treatment of PLGA. Sirolimus and paclitaxel were loaded into PEC and PLGA in order to study drug release performance. Attenuated total reflectance–infrared (ATR– FTIR) spectroscopy of sirolimus, PEC and the sirolimus-loaded PEC coating showed that no chemical reaction occurred between sirolimus and PEC. The results of atomic force microscopy (AFM) revealed that the mean roughness (Ra) values of the bare metal stent (BMS) and the drugeluting stent (DES) were 2.3 nm and 1.0 nm, respectively. After balloon expansion experiments, no delamination or destruction of the PEC coating was observed. The drug release profile of sirolimus was different from that of paclitaxel when PEC was employed as the drug carrier, and the release curves of sirolimus were different when PEC and PLGA were used as drug carriers. All the experimental results demonstrated that PEC was one of the best potential stent-coating materials.