全文获取类型
收费全文 | 330篇 |
免费 | 25篇 |
出版年
2023年 | 3篇 |
2021年 | 6篇 |
2019年 | 2篇 |
2018年 | 5篇 |
2017年 | 7篇 |
2016年 | 5篇 |
2015年 | 16篇 |
2014年 | 26篇 |
2013年 | 18篇 |
2012年 | 23篇 |
2011年 | 17篇 |
2010年 | 11篇 |
2009年 | 16篇 |
2008年 | 15篇 |
2007年 | 15篇 |
2006年 | 23篇 |
2005年 | 11篇 |
2004年 | 7篇 |
2003年 | 16篇 |
2002年 | 17篇 |
2001年 | 11篇 |
2000年 | 9篇 |
1999年 | 3篇 |
1998年 | 2篇 |
1995年 | 2篇 |
1994年 | 2篇 |
1992年 | 2篇 |
1991年 | 2篇 |
1990年 | 4篇 |
1989年 | 2篇 |
1988年 | 4篇 |
1987年 | 3篇 |
1986年 | 3篇 |
1984年 | 2篇 |
1983年 | 2篇 |
1981年 | 1篇 |
1980年 | 1篇 |
1979年 | 1篇 |
1977年 | 1篇 |
1975年 | 1篇 |
1969年 | 1篇 |
1966年 | 1篇 |
1885年 | 1篇 |
1879年 | 3篇 |
1878年 | 6篇 |
1877年 | 6篇 |
1876年 | 6篇 |
1875年 | 5篇 |
1872年 | 2篇 |
1862年 | 1篇 |
排序方式: 共有355条查询结果,搜索用时 31 毫秒
341.
Anett Richter Jennifer Hauck Reinart Feldmann Elisabeth Kühn Alexander Harpke Norbert Hirneisen Anika Mahla Josef Settele Aletta Bonn 《Journal of Insect Conservation》2018,22(5-6):731-743
Insect conservation needs sound information on species distribution trends. Developing this evidence relies—in practice—on long-term engagement of volunteers who observe and record species over large spatial and temporal scales. Many biodiversity monitoring schemes, including those for insects, are highly dependent on conservation-based citizen science programs with a long-term continuity. As these schemes are built entirely on good will, the nature of social relations and networks is pivotal to success. We assess the working mechanism of a monitoring scheme that is citizen-based as a case study. The German Butterfly Monitoring Scheme (hereafter TMD for “Tagfalter-Monitoring Deutschland”) operates, as many other citizen science monitoring schemes, through an overarching national network of regional subnetworks of volunteers and a central scientific coordination. Using a questionnaire survey paired with a visual social network assessment, we investigate how participants interact within these networks and assess their motivations to engage. We characterise the functionality of this social network based on mechanism of coordination and participation, flows of information and knowledge exchange among recorders, regional and central coordinators, academic scientists and institutions. By analyzing the interactions, we show how the social network facilitates and ensures various communication modes and thereby fosters long-term engagement, stability and growth of the scheme. We identify the central role of project coordination and the importance of social relations within citizen-based monitoring programs for engagement and personal satisfaction. Based on our empirical study, we derive a set of recommendations for establishing and maintaining successful volunteer networks in insect citizen-based monitoring programs. 相似文献
342.
U T Seyfert W Hauck H Berger D B?hm H Zankl F W Albert 《Folia haematologica (Leipzig, Germany : 1928)》1990,117(5):685-697
Several reports have appeared with regard to the potential role of platelets in tumor cells metastasis. Our in vitro studies with colon tumor cells in normals and in patients give some evidence against platelet aggregation as the determinant factor in tumor cell invasion and metastasis. Dimethylhydrazine induced colon tumors in Wistar rats demonstrate characteristic features of tumor cell dissociation in the invasion line and changes in intercellular adhesion. 相似文献
343.
F. Hauck 《Plant Systematics and Evolution》1876,26(12):412-414
Ohne Zusammenfassung 相似文献
344.
345.
F. Hauck 《Plant Systematics and Evolution》1877,27(4):117-118
Ohne Zusammenfassung 相似文献
346.
347.
The elastin-laminin receptor] 总被引:1,自引:0,他引:1
T Fül?p M P Jacob J Wallach M Hauck I Seres Z Varga L Robert 《Journal de la Société de Biologie》2001,195(2):157-164
Elastin is a major component of the extracellular matrix. Elastin peptides derived from its degradation are present in human sera. Elastin peptides induce on fibroblasts, phagocytic cells, lymphocytes, smooth muscle cells and endothelial cells, a variety of biological effects mediated by the elastin-laminin receptor which has been demonstrated to be present on the membrane of these cells. The transduction pathway of the ELR receptor involves the activation of phospholipase C (PLC) by a pertussis toxin sensitive G-protein. PLC induces the production of inositol trisphosphate (IP3) leading to the increase of the intracellular free calcium on one hand, and of diacylglycerol (DAG) which stimulates the translocation to the membrane of PKC leading to the phosphorylation of members of the MAPK family, such as p42/p44 MAPK. Considering the multiple biological effects of ELR the elucidation of the complexity of the signaling pathways will help to better modulate it, mainly in pathological situations such as atherosclerosis. 相似文献
348.
Tselmeg Chenlemuge Dietrich Hertel Choimaa Dulamsuren Mookhor Khishigjargal Christoph Leuschner Markus Hauck 《Flora》2013,208(8-9):488-496
Mongolia's Larix sibirica forests at the southern fringe of the Eurosiberian boreal forest belt are exposed not only to very low winter temperatures, but also to frequent summer droughts. It is not completely known how Siberian larch adapts to these stressors. We examined whether (i) these forests differ in their fine root bio- and necromass from more humid boreal forests further in the North and (ii) inter-annual fluctuations in fine root biomass are related to tree vitality. In two exceptionally dry summers, we found only 4–5 g DM m?2 of fine root biomass (in 0–20 cm depth), which is far less than typical conifer fine root biomass figures from boreal forests (c. 200–400 g m?2) and the lowest forest fine root biomass reported worldwide; in a moist summer, fine root biomass was 20 fold higher. In contrast to fine root biomass, both necromass and non-tree root mass were high in all three years. From the large increase of fine root biomass in the moist summer and the generally high root necromass, we conclude that drought-induced fine root dieback was the likely cause of the very small amount of live root mass in the dry summers. Larch fine roots seem to be more drought-sensitive than shoots, since marked needle loss did not occur under the extreme conditions. 相似文献
349.
350.
Dr. Ferdinand Hauck 《Plant Systematics and Evolution》1885,35(4):144-145
Ohne Zusammenfassung 相似文献