全文获取类型
收费全文 | 147篇 |
免费 | 3篇 |
国内免费 | 1篇 |
出版年
2017年 | 1篇 |
2016年 | 2篇 |
2014年 | 2篇 |
2013年 | 2篇 |
2012年 | 5篇 |
2011年 | 12篇 |
2010年 | 14篇 |
2009年 | 10篇 |
2008年 | 6篇 |
2007年 | 5篇 |
2006年 | 5篇 |
2005年 | 2篇 |
2004年 | 1篇 |
2003年 | 1篇 |
2002年 | 1篇 |
2001年 | 2篇 |
2000年 | 4篇 |
1999年 | 3篇 |
1998年 | 2篇 |
1997年 | 2篇 |
1996年 | 5篇 |
1995年 | 4篇 |
1994年 | 4篇 |
1993年 | 2篇 |
1992年 | 2篇 |
1991年 | 4篇 |
1990年 | 2篇 |
1989年 | 5篇 |
1988年 | 4篇 |
1987年 | 1篇 |
1986年 | 2篇 |
1985年 | 2篇 |
1984年 | 1篇 |
1983年 | 4篇 |
1982年 | 2篇 |
1981年 | 9篇 |
1980年 | 2篇 |
1978年 | 1篇 |
1977年 | 1篇 |
1976年 | 1篇 |
1974年 | 2篇 |
1973年 | 1篇 |
1971年 | 2篇 |
1970年 | 1篇 |
1969年 | 1篇 |
1968年 | 1篇 |
1966年 | 1篇 |
1962年 | 1篇 |
1953年 | 1篇 |
排序方式: 共有151条查询结果,搜索用时 15 毫秒
61.
Habitat variation,mutualism and predation shape the spatio‐temporal dynamics of tansy aphids
下载免费PDF全文
![点击此处可从《Ecological Entomology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
1. Spatially distributed resources can lead to the formation of metapopulations, where individual subpopulations are often small and can experience frequent local extinction events followed by recolonisation. An example of terrestrial metapopulations are specialised phytophagous insects on their patchily distributed host plants. 2. The present study investigated the population dynamics of a specialised aphid (Metopeurum fuscoviride) on its patchily distributed host plant (Tanacetum vulgare) and associated community of mutualistic ants and predators in a small‐scale field site. Furthermore, aphid habitat differences (plant size, C/N ratio, location and surrounding vegetation) were quantified, and seasonal timing and precipitation were considered. 3. Seasonal timing and precipitation both had effects on aphid colonisation, extinction events and aphid colony persistence. Towards the end of the season, and after higher precipitation, aphid colonisation events decreased and extinction events increased. Plant size and location as well as aphid within‐field dispersal determined the spatio‐temporal distribution of aphid colonies. 4. Mutualistic ants (Lasius niger and Myrmica rubra) increased the chance of establishment of aphid colonies. However, when M. rubra was tending, aphid colony persistence was reduced. Aphid persistence and extinction were dependent on aphid abundance, as a higher colony size reduced the probability of extinction by predation. 5. The results emphasise the importance of dispersal limitation, population growth and the presence of mutualists when studying the spatio‐temporal dynamics of tansy aphids, particularly in a small‐scale field site. 相似文献
62.
WOLFGANG ARTHOFER SILVIO SCHÜLER FLORIAN M. STEINER BIRGIT C. SCHLICK‐STEINER 《Molecular ecology》2010,19(18):3853-3856
Ongoing genetic transfer from mitochondria and plastids into the nucleus is a well‐documented fact. While in metazoan molecular ecology the need for surveillance against pseudogene‐mediated artefacts when analysing mtDNA sequences is commonly accepted, no comparable measurements have been established for plastid‐based studies. We highlight the impact and management of nuclear mitochondrial insertions, argue that nuclear plastid sequences represent an underestimated but major factor in plant molecular ecology, and discuss potential avenues of remedy in chloroplast studies. 相似文献
63.
64.
NORMAN SARTORIUS WOLFGANG GAEBEL HELEN‐ROSE CLEVELAND HEATHER STUART TSUYOSHI AKIYAMA JULIO ARBOLEDA‐FLÓREZ ANJA E. BAUMANN OYE GUREJE MIGUEL R. JORGE MARIANNE KASTRUP YURIKO SUZUKI ALLAN TASMAN 《World psychiatry》2010,9(3):131-144
In 2009 the WPA President established a Task Force that was to examine
available evidence about the stigmatization of psychiatry and psychiatrists
and to make recommendations about action that national psychiatric societies
and psychiatrists as professionals could do to reduce or prevent the stigmatization
of their discipline as well as to prevent its nefarious consequences. This
paper presents a summary of the Task Force’s findings and recommendations.
The Task Force reviewed the literature concerning the image of psychiatry
and psychiatrists in the media and the opinions about psychiatry and psychiatrists
of the general public, of students of medicine, of health professionals other
than psychiatrists and of persons with mental illness and their families.
It also reviewed the evidence about the interventions that have been undertaken
to combat stigma and consequent discrimination and made a series of recommendations
to the national psychiatric societies and to individual psychiatrists. The
Task Force laid emphasis on the formulation of best practices of psychiatry
and their application in health services and on the revision of curricula
for the training of health personnel. It also recommended that national psychiatric
societies establish links with other professional associations, with organizations
of patients and their relatives and with the media in order to approach the
problems of stigma on a broad front. The Task Force also underlined the role
that psychiatrists can play in the prevention of stigmatization of psychiatry,
stressing the need to develop a respectful relationship with patients, to
strictly observe ethical rules in the practice of psychiatry and to maintain
professional competence. 相似文献
65.
DIMITRIOS N. AVTZIS WOLFGANG ARTHOFER CHRISTIAN STAUFFER 《Biological journal of the Linnean Society. Linnean Society of London》2008,94(2):331-340
Differentiation among the European populations of the six-toothed spruce bark beetle Pityogenes chalcographus was observed for the first time in the 1970s as mating males from Northern Europe with females from Central Europe led to a significant decline in fecundity. Morphological examination revealed that P. chalcographus can be separated into two European races. Here, we investigated the genetic background of this separation by analysing 39 populations ( n = 695), sequencing almost the complete cytochrome oxidase I gene (1543 bp) and applying single-strand conformation polymorphism. Phylogenetic analysis of 58 haplotypes yielded three major clades with a maximum sequence divergence of 2.33%, indicating that the demographic events took place in the late Pleistocene. These results support the hypothesis of allopatric divergence of the mtDNA lineages, which postglacially came into sympatric existence in Europe. However, as a result of partial crossing incompatibility the diverged lineages retained their genetic identity during postglacial times. © 2008 The Linnean Society of London, Biological Journal of the Linnean Society , 2008, 94 , 331–340. 相似文献
66.
YIQI LUO DIETER GERTEN† GUERRIC LE MAIRE‡ WILLIAM J. PARTON§ ENSHENG WENG XUHUI ZHOU CINDY KEOUGH§ CLAUS BEIER¶ PHILIPPE CIAIS‡ WOLFGANG CRAMER† JEFFREY S. DUKES BRIDGET EMMETT†† PAUL J. HANSON‡‡ ALAN KNAPP§§ SUNE LINDER¶¶ DAN NEPSTAD LINDSEY RUSTAD 《Global Change Biology》2008,14(9):1986-1999
Interactive effects of multiple global change factors on ecosystem processes are complex. It is relatively expensive to explore those interactions in manipulative experiments. We conducted a modeling analysis to identify potentially important interactions and to stimulate hypothesis formulation for experimental research. Four models were used to quantify interactive effects of climate warming (T), altered precipitation amounts [doubled (DP) and halved (HP)] and seasonality (SP, moving precipitation in July and August to January and February to create summer drought), and elevated [CO2] (C) on net primary production (NPP), heterotrophic respiration (Rh), net ecosystem production (NEP), transpiration, and runoff. We examined those responses in seven ecosystems, including forests, grasslands, and heathlands in different climate zones. The modeling analysis showed that none of the three‐way interactions among T, C, and altered precipitation was substantial for either carbon or water processes, nor consistent among the seven ecosystems. However, two‐way interactive effects on NPP, Rh, and NEP were generally positive (i.e. amplification of one factor's effect by the other factor) between T and C or between T and DP. A negative interaction (i.e. depression of one factor's effect by the other factor) occurred for simulated NPP between T and HP. The interactive effects on runoff were positive between T and HP. Four pairs of two‐way interactive effects on plant transpiration were positive and two pairs negative. In addition, wet sites generally had smaller relative changes in NPP, Rh, runoff, and transpiration but larger absolute changes in NEP than dry sites in response to the treatments. The modeling results suggest new hypotheses to be tested in multifactor global change experiments. Likewise, more experimental evidence is needed for the further improvement of ecosystem models in order to adequately simulate complex interactive processes. 相似文献
67.
WOLFGANG EDRICH 《Physiological Entomology》1981,6(1):7-13
ABSTRACT. In accordance with the peculiarities of the sun's azimuthal path near the equator, African honey bees observed in their night-time dances apparently allowed for the azimuth moving backwards at night relative to its day-time movement. In several cases the bees evidently inferred the actual azimuthal position of the sun, rather than the one that would result from extrapolating a uniform movement of the sun. 相似文献
68.
69.
Terrestrial immigrants from the sea have to cope with two importantnutritional problems: a shift in pathways of absorption, andthe altered availability of nutrients. The more terrestrialspecies of littoral crustaceans switch to food as the main sourceof water and salts. No serious difficulties accompany the oraluptake of mobile ions, but the vegetarians amongst the immigrantsare required to assume a new attitude with regard to the assimilationor heavier metals. Some important heavy elements, notably Cuand Zn, are soluble in sea water but form rather intractableorganic complexes in plant tissues. Herbivorous amphipods andisopods on land are incapable of extracting copper directlyfrom their primary food sources. To compensate for this shortcoming,help is enlisted from microorganisms, which render the copperpresent in ill-digested fecal material available to the crustaceans.Moreover, in terrestrial and intertidal herbivorous crustaceansascompared with their marine relativesthe storage capacityof the hepatopancreas, as well as the efficiency of Cu-assimilation,is augmented; compartmentalization of Cu-storage is more rigorouslycarried through; the movements of Cu and Zn within the bodyare more strictly regulated, copper, for example, being exchangedbetween different compartments in the course of endogenouslyor exogenously induced phases of the animal's life cycle. 相似文献
70.
WUBISHET A. BEKELE KARIN FIEDLER AMUKELANI SHIRINGANI DANIEL SCHNAUBELT STEFFEN WINDPASSINGER RALF UPTMOOR WOLFGANG FRIEDT ROD J. SNOWDON 《Plant, cell & environment》2014,37(3):707-723
Sorghum is a promising alternative to maize for bioenergy production in Europe; however, its use is currently limited by poor adaptation to low temperatures during and after germination. We collected multi‐trait phenotype data under optimal and suboptimal temperatures in a genetically diverse recombinant inbred line (RIL) mapping population showing contrasting segregation patterns for pre‐ and post‐emergence chilling tolerance. Germination, emergence, seedling development, root architecture and seedling survival were assessed in two different seedlots. Emergence and root establishment were found to be the key determinants of development and survival under chilling stress. Highly interactive epistatic quantitative trait loci (QTL) hotspots, including a previously unknown QTL on Sb06 with a significant effect on prolonged chilling survival, were found to regulate different physiological mechanisms contributing to maintenance of growth and development despite the chilling temperatures. The major QTL regions harbour promising candidate genes with known roles in abiotic stress tolerance. Identification of loci in the QTL hotspot regions conferring maintenance of cell division and growth under early chilling stress represents a promising step towards breeding for successful establishment of sorghum in temperate climates. 相似文献