全文获取类型
收费全文 | 93篇 |
免费 | 4篇 |
国内免费 | 3篇 |
专业分类
丛书文集 | 1篇 |
理论与方法论 | 1篇 |
现状及发展 | 16篇 |
综合类 | 77篇 |
自然研究 | 5篇 |
出版年
2022年 | 2篇 |
2021年 | 2篇 |
2019年 | 3篇 |
2018年 | 2篇 |
2017年 | 1篇 |
2016年 | 1篇 |
2015年 | 1篇 |
2014年 | 5篇 |
2013年 | 4篇 |
2012年 | 9篇 |
2011年 | 3篇 |
2010年 | 1篇 |
2009年 | 4篇 |
2008年 | 6篇 |
2007年 | 8篇 |
2006年 | 9篇 |
2005年 | 4篇 |
2004年 | 1篇 |
2003年 | 1篇 |
2002年 | 5篇 |
2001年 | 3篇 |
2000年 | 8篇 |
1998年 | 1篇 |
1997年 | 1篇 |
1996年 | 1篇 |
1995年 | 2篇 |
1994年 | 2篇 |
1993年 | 3篇 |
1992年 | 1篇 |
1991年 | 1篇 |
1990年 | 1篇 |
1989年 | 1篇 |
1987年 | 2篇 |
1985年 | 1篇 |
排序方式: 共有100条查询结果,搜索用时 15 毫秒
21.
面孔识别是近年来心理学研究的热点问题,通过对以往文献的分析,发现面孔识别具有特异性,以及面孔识别的两大模型的不足之处,并展望了面孔识别的未来研究趋势. 相似文献
22.
毛腿鼠耳蝠Myotis fimbriatus不同组织酯酶同工酶的比较 总被引:2,自引:1,他引:2
采用聚丙烯酰胺不连续凝胶垂直板活性电泳,分析了毛腿鼠耳蝠的心脏、肝脏、肾脏、胸肌、肺、胃、小肠、舌8种组织的酯酶.结果表明:毛腿鼠耳蝠8种组织的酯酶同工酶存在差异,其分布和活性具有明显的组织特异性,与器官或组织所执行的功能有关. 相似文献
23.
24.
Rana oocytes have previously been shown to contain much more soluble tubulin than does the brain, suggesting different assembly
and disassembly dynamics of frog oocyte tubulin compared to that in brain. By using centrifugation, SDS-PAGE, two-dimensional
gel electrophoresis and Western blots, probed with anti-α-tubulin monoclonal antibodies, polymorphic α-tubulins (isoforms)
were compared in brains and follicle-enclosed oocytes of northern (Rana pipiens) and southern (R. berlandieri) frogs. Oocyte tubulin in both species had isoforms with greater ranges of isoelectric point (pI) than those of brain tubulins;
in particular, the oocyte tubulin pIs ranged further into the acidic region of the isoelectric-focusing gels than corresponding
brain tubulin. This difference may, in part, be responsible for the previously reported assembly differences between oocyte
tubulin (undetectable assembly) and brain tubulin (high assembly). Isoforms of α-tubulin with relat
ively acidic pI were more abundant in northern frog brain and oocyte soluble extracts than in analogous extracts from southern
frogs. Furthermore, additional acidic α-tubulin isoforms were found in progesterone-treated oocytes (i.e., eggs), indicating
increased heterogeneity of acidic a-tubulin isoforms during oocyte meiotic maturation. Among northern frog oocyte soluble
components fractionated on Superose-6b columns, tubulin complexes with apparent molecular mass of about 1800 kDa were found
to contain acidic α-tubulin isoforms while the putative oligomeric tubulins with an apparent molecular mass of about 250 kDa
contained an additional relatively basic α-tubulin isoform. The acidic α-tubulin isoforms, therefore, are proposed to be associated
with cold-adaptable cells of brain and oocytes, and may also be involved in stabilization of large soluble tubulin complexes
in oocytes of the northern frog.
Received 1 October 2002; accepted 9 October 2002
RID="*"
ID="*"Corresponding author. 相似文献
25.
26.
《Journal of Natural History》2012,46(2):357-379
Known host-plant associations are listed for the 16 species of Eupteryx occurring in Britain. A total of 77 species in 17 plant families are exploited. The most frequently represented plant family is the Labiatae. Degrees of specificity range from strict monophagy (four spp.) to broad polyphagy (five spp.). In general, host-plant overlap between species is low. The detailed relationships between three Eupteryx species and three members of the Urticaceae were explored using field populations and laboratory feeding experiments, survival tests and examination of patterns of oviposition. Eupteryx urticae, E. cyclops and E. aurata all utilized Urtica dioica as their primary host plant. However, the only regularly recorded association with other members of the Urticaceae was the host range expansion of E. urticae onto Parietaria judaica in the second generation. These findings were supported by the laboratory experiments. The spatial distributions of E. urticae oviposition sites and levels of attack by mymarid parasitoids were similar in populations on the two plant species. The implications of these results are discussed. 相似文献
27.
28.
批处理依赖是一种特殊的函数依赖,但其定义的推理规则过于严格而不适用于含噪数据.为了从含噪数据中挖掘出有价值的批处理依赖,在批处理依赖研究的基础上,提出了近似批处理依赖的概念,并通过引入可信度、特异度等度量指标,提出了相应的近似批处理依赖挖掘算法;最后通过实例说明了算法过程及其有效性. 相似文献
29.
J. van Brederode R. Kamps-Heinsbroek J. Steyns 《Cellular and molecular life sciences : CMLS》1987,43(2):202-205
Summary The variation in flavone glycosylation patterns inSilene is the result of the expression of six genetic loci, which control either the presence of allozymes differing in substrate specificity or isozymes regulated differently during development. Serological studies showed that at least three of these six loci are evolutionarily related. The genetic mechanisms leading to these complicated variation patterns and the role of this polymorphism for the plant in its interaction with the environment are discussed. 相似文献
30.
传统的药物粉末流动性检测方法对物性接近的粉末流动性差异区分度不高,造成部分受粉末流动性影响较大的工艺缺少对材料进行准确物性评价。针对这一问题,以8种乳糖为药物模型,研究基于振动微量下料技术的药物粉末流动性检测方法。根据粉末流动的质量流量、连续与间断下料的流速变化等情况,由粉体流动方程推导得到下料流速与过程参数间的关系式,给出了表征流动性的特征常数。结果表明,基于振动微量下料技术的药物粉末流动性检测方法适用于中值粒径为20~135 μm的药物粉末,对在这个粒径范围内物性相近的乳糖的流动性有明显的区分度,并具有在其他更多的药物粉末流动性检测中推广的潜力及良好的工业应用价值。 相似文献