全文获取类型
收费全文 | 341篇 |
免费 | 22篇 |
出版年
2021年 | 4篇 |
2018年 | 5篇 |
2017年 | 9篇 |
2016年 | 10篇 |
2015年 | 10篇 |
2014年 | 7篇 |
2013年 | 15篇 |
2012年 | 11篇 |
2011年 | 19篇 |
2010年 | 11篇 |
2009年 | 7篇 |
2008年 | 6篇 |
2007年 | 7篇 |
2006年 | 6篇 |
2005年 | 8篇 |
2004年 | 7篇 |
2003年 | 10篇 |
2001年 | 10篇 |
2000年 | 5篇 |
1999年 | 7篇 |
1998年 | 4篇 |
1997年 | 8篇 |
1995年 | 5篇 |
1993年 | 5篇 |
1992年 | 3篇 |
1990年 | 3篇 |
1989年 | 5篇 |
1988年 | 7篇 |
1987年 | 4篇 |
1986年 | 3篇 |
1985年 | 5篇 |
1984年 | 7篇 |
1983年 | 8篇 |
1981年 | 3篇 |
1980年 | 3篇 |
1979年 | 5篇 |
1978年 | 3篇 |
1971年 | 3篇 |
1961年 | 3篇 |
1960年 | 3篇 |
1954年 | 2篇 |
1953年 | 4篇 |
1950年 | 3篇 |
1942年 | 2篇 |
1940年 | 4篇 |
1936年 | 18篇 |
1933年 | 13篇 |
1932年 | 8篇 |
1931年 | 11篇 |
1929年 | 4篇 |
排序方式: 共有363条查询结果,搜索用时 15 毫秒
1.
Background
Phylogenies capture the evolutionary ancestry linking extant species. Correlations and similarities among a set of species are mediated by and need to be understood in terms of the phylogenic tree. In a similar way it has been argued that biological networks also induce correlations among sets of interacting genes or their protein products. 相似文献2.
3.
4.
Urinary TXB2 excretion was measured during pregnancy and labor using high pressure liquid chromatography and radioimmunoassay. From the first trimester onwards TXB2 levels in urine of pregnant women (n = 60) were significantly (p less than 0.001) higher than in non-pregnant women (n = 12) and they increased, albeit not significantly, with advancing gestation. Labor was associated with a two-fold increase in urinary TXB2 excretion. Levels in established labor were significantly higher than at any other time in pregnancy (p less than 0.001), but the levels in incipient labor showed considerable overlap with these in late pregnancy. Thus urinary TXB2, while not necessarily originating from the pregnant uterus, appears to reflect the uterine activity of labor and may be the expression of a general stimulation of prostanoid production during parturition. 相似文献
5.
Biological sensors are becoming more important to monitor the quality of the aquatic environment. In this paper the valve movement response of freshwater (Dreissena polymorpha) and marine (Mytilus edulis) mussels is presented as a tool in monitoring studies. Examples of various methods for data storage and data treatment are presented, elucidating easier operation and lower detection limits. Several applications are mentioned, including an early warning system based on this valve movement response of mussels. 相似文献
6.
Urinary excretion of 6-keto-PGF1α was measured by high pressure liquid chromatography and radioimmunoassay at various stages of pregnancy and labor. In the first trimester of pregnancy, urinary 6-keto-PGF1α concentrations were nor different from those measured before pregnancy, but they showed a significant increase in the second trimester of pregnancy (p <0.001). The levels rose further in the third trimester, although this increase was not statistically significant when compared to levels obtained in the second trimester. There was no evidence for a significance change in 6-keto-PGF1α excretion with the onset of labor. During well-established, progressive labor mean values of 6-keto-PGF1α excretion were about twice as high as before the onset of labor, but the range of values during labor was so wide that there was no statistical difference with values obtained in the second half of pregnancy.It is concluded that the increase in the urinary excretion of 6-keto-PGF1α occurs later in pregnancy than the increase in TXB2 excretion and that labor at term is not associated with marked changes in 6-keto-PGF1α excretion. 相似文献
7.
8.
9.
南瓜雌蕊与自花及远缘花粉的相互作用 总被引:2,自引:0,他引:2
南瓜柱头表面经去垢剂、蛋白酶及Con A处理后花粉不能萌发或花粉管生长受阻,Con A能专一地与柱头表面结合。柱头块加入培养液可促进花粉萌发。不同的远缘花粉授粉后在雌蕊不同部位受阻。在成熟南瓜雌蕊提取液中检测到血凝活性,凝集素可能参与雌蕊对远缘花粉的抑制。 相似文献
10.
In a specified pathogen free (SPF) breeding colony of IIIVO/JU rabbits 8 cases of prolapsus vaginae occurred in 5 years. Clinically the animals were in shock. Haematocrits ranged from 9 to 15%. The prolapses started from the submucosal layer of the proximal part of the vestibulum vaginae. The prolapsed tissue consisted of over-expanded blood-sinuses. Between the sinuses signs of an inflammatory reaction were present. All 8 animals were in a period of increasing sexual activity when the prolapse developed. The 8 rabbits were closely related, indicating a possible hereditary defect. 相似文献