全文获取类型
收费全文 | 101篇 |
免费 | 0篇 |
专业分类
系统科学 | 1篇 |
现状及发展 | 56篇 |
研究方法 | 3篇 |
综合类 | 40篇 |
自然研究 | 1篇 |
出版年
2020年 | 1篇 |
2019年 | 1篇 |
2015年 | 1篇 |
2013年 | 1篇 |
2012年 | 1篇 |
2011年 | 5篇 |
2010年 | 1篇 |
2008年 | 1篇 |
2007年 | 2篇 |
2006年 | 1篇 |
2005年 | 1篇 |
2004年 | 4篇 |
2003年 | 3篇 |
2002年 | 1篇 |
2001年 | 1篇 |
1996年 | 1篇 |
1993年 | 2篇 |
1992年 | 5篇 |
1991年 | 3篇 |
1990年 | 1篇 |
1985年 | 1篇 |
1984年 | 1篇 |
1982年 | 2篇 |
1978年 | 3篇 |
1976年 | 1篇 |
1975年 | 3篇 |
1974年 | 4篇 |
1973年 | 5篇 |
1972年 | 1篇 |
1971年 | 3篇 |
1970年 | 3篇 |
1969年 | 6篇 |
1968年 | 8篇 |
1967年 | 5篇 |
1966年 | 9篇 |
1965年 | 3篇 |
1963年 | 1篇 |
1956年 | 1篇 |
1955年 | 1篇 |
1948年 | 1篇 |
1947年 | 2篇 |
排序方式: 共有101条查询结果,搜索用时 15 毫秒
61.
62.
Zusammenfassung In den Seitenventrikeln wurden intraventrikuläre Zellfortsätze beobachtet. Ein Teil davon ähnelt Neuritenendigungen, wie sie bereits von anderen Autoren im III. und IV. Ventrikel beobachtet wurden. Sie enthalten die typischen Bestandteile präsynaptischer Elemente; die Vesikel sind jedoch nicht an den desmosomenartigen Kontakten mit dem Ependymapex aggregiert. Ihre Umhüllung mit Mikrovilli könnte für eine Rezeptorfunktion sprechen. Andere Fortsätze sind ependymaler Herkunft. 相似文献
63.
64.
S. P. Wolff 《Cellular and molecular life sciences : CMLS》1992,48(3):301-304
Although there is widespread agreement that many cancers have environmental causes we are often unable to see associations between specific cancers and exposure to environmental chemicals. One might also speulate that the more widespread, common-place and normal a chemical exposure is perceived to be then the less likely it will be that the exposure is recognised, let alone be considered to cause cancer. Widespread contamination of air by chemicals associated with internal combustion may be an example of one such invisible carcinogenic exposure. Yet evidence is available which suggests that many leukaemia and lymphoma cases, as well as other cancers, may be caused by this mundane and ubiquitous environmental contamination. The hypothesis is developed that leukaemia clustering as well as national leukaemia incidence may be related to non-occupational exposure to benzene formed by petrol combustion and resulting from petrol evaporation1. The possible association between exposure to fuel vapours, internal combustion products and cancer merits much closer examination than it receives at present. 相似文献
65.
Summary We show that there are correlations in regenerative fresh water planarians between all the parts of the body. When planarians are wounded in any part of the body, this mutilation will set regenerative cells in movement, which are able to travel a very long way in their migration. The extent and the speed of migration haves been shown by the method of localized X-ray irradiations.When the regenerative cells that are nearest to the wound have been killed with X-rays, regeneration occurs through the access of cells from the farther parts of the body. The nature of the stimulus is not yet known. 相似文献
66.
多梯度复杂图像的分割 总被引:1,自引:1,他引:0
图像分割是一种重要的图像分析技术,它不仅得到人们广泛的重视和研究,也在实际中得到大量的应用。本文针对一些经典分割算法对多梯度复杂图像分割边缘定位不准确,易受噪声干扰的特点,提出了一种利用图像边缘区域对多梯度复杂图像进行自适应阈值分割的算法。通过对各种算法的比较,本算法抗干扰能力较强,稳定性好,而且完全自动,不需预先设定任何参数。对多种图像的实验表明本文方法十分有效。 相似文献
67.
68.
In this paper I take a close look at the SI base quantity “amount of substance”, and its unit, the mole. The mole was introduced as a base unit in the SI in 1971, and there is currently a proposal to change its definition. The current definition of the mole shows a certain ambiguity regarding the nature of the quantity “amount of substance”. The proposed new definition removes the ambiguity, but at a cost: it becomes difficult to justify treating amount of substance as having its own dimension, and hence its own unit, the mole. I argue that the difficulties with amount of substance result from its role as a mediator between macroscopic and microscopic scales. To understand why amount of substance might have its own dimension, we need to connect amount of substance to mass, contra current proposals to separate them. 相似文献
69.
Distributional data are presented for 30 species of New Mexico Plecoptera including 8 species new to the state list. Previously, many of the included species were known from a single location in the state. A revised checklist of 46 confirmed species is presented for the state. 相似文献
70.