全文获取类型
收费全文 | 223篇 |
免费 | 4篇 |
出版年
2013年 | 4篇 |
2012年 | 4篇 |
2011年 | 3篇 |
2010年 | 6篇 |
2009年 | 7篇 |
2008年 | 3篇 |
2007年 | 8篇 |
2006年 | 4篇 |
2005年 | 5篇 |
2004年 | 3篇 |
1998年 | 6篇 |
1995年 | 6篇 |
1992年 | 4篇 |
1991年 | 4篇 |
1990年 | 4篇 |
1989年 | 4篇 |
1988年 | 2篇 |
1987年 | 2篇 |
1986年 | 2篇 |
1985年 | 6篇 |
1984年 | 2篇 |
1983年 | 3篇 |
1982年 | 4篇 |
1981年 | 3篇 |
1980年 | 6篇 |
1979年 | 5篇 |
1978年 | 9篇 |
1977年 | 8篇 |
1976年 | 6篇 |
1975年 | 5篇 |
1974年 | 8篇 |
1973年 | 2篇 |
1972年 | 3篇 |
1970年 | 2篇 |
1969年 | 2篇 |
1968年 | 4篇 |
1967年 | 2篇 |
1965年 | 2篇 |
1963年 | 4篇 |
1962年 | 2篇 |
1960年 | 3篇 |
1959年 | 2篇 |
1958年 | 5篇 |
1957年 | 3篇 |
1956年 | 4篇 |
1955年 | 4篇 |
1953年 | 2篇 |
1951年 | 2篇 |
1950年 | 5篇 |
1949年 | 6篇 |
排序方式: 共有227条查询结果,搜索用时 15 毫秒
101.
102.
The ATP pool of growing fungal mycelia, particularly Fomes annosus, has been determined. The ATP level varied during the different growth phases and correlated with the variations in the economic coefficient. Common uncouplers (at concentrations similar to those used in mitochondrial tests) decreased the ATP pool very rapidly. The size of the pool often fell 50–80% before the O2 uptake decreased below that of the control and was accompanied by an increasing exudation of inorganic phosphate. Phenolic compounds added to the medium stimulated the lacease activity, generally in combination with a decrease in the ATP level. 相似文献
103.
104.
105.
P. HADLEY G. R. BATTS R. H. ELLIS J. I. L. MORISON S. PEARSON T. R. WHEELER 《Plant, cell & environment》1995,18(9):1055-1063
A temperature gradient chamber (TGC) is described which enables elevated CO2 concentrations and a dynamic temperature gradient to be imposed on field crops throughout their life cycle under standard husbandry. Air is circulated through two double-walled polyethylene-covered tunnels connected to a split heat pump system to give a near-linear temperature gradient along each tunnel. Solar energy gain along each tunnel and exchange with outer tunnel air flow contribute to the temperature gradient and also produce diurnal and seasonal temperature fluctuations corresponding to ambient conditions. Mean temperature gradients of between 3 and 5°C have been recorded throughout the growing seasons of crops of lettuce, carrot, cauliflower and winter wheat. Elevated or present CO2 concentrations are maintained in each of two pairs of tunnels throughout the cropping season using pure CO2 injected through motorized needle valves. This system can realistically simulate aspects of the effects of projected future environmental change on crop growth, development and yield, and in particular tin-possible interaction of the effects of increased CO2 and temperature. 相似文献
106.
Long pollinia on eyes: hawk-moth pollination of Cynorkis uniflora Lindley (Orchidaceae) in Madagascar 总被引:2,自引:0,他引:2
L. ANDERS NILSSON ELISABETH RABAKONANDRIANINA ROTAHARIVELO RAZANANAIVO JEAN-JACQUES RANDRIAMANINDRY 《Botanical journal of the Linnean Society. Linnean Society of London》1992,109(1):145-160
NILSSON, L. A., RABAKONANDRIANINA, E., RAZANANAIVO, R. & RANDRIAMANINDRY, J.J., 1992. Long pollinia on eyes: hawk-moth pollination of Cynorkis uniflora Lindley (Orchidaceae) in Madagascar. The pollination biology of Cynorkis uniflora Lindley (Orchidaceae) was studied on a rocky outcrop in a fragment of montane rain forest in central Madagascar. The plant was obligately pollinated by hawk-moths. Nectar was produced in a floral spur and was accessible to hawk-moths with medium-long and long tongues. All observed visits took place during the 80 min following dusk. Floral traits and visits indicated pollination association with endemic hawk-moths of the genera Nephete and Hippotion with medium tongue length and early-evening habits. The orchid pollinia had extraordinarily long caudicles (c. 16 mm) and were carried attached to the hawk-moths' eyes, thus protruding far in front of the face of the pollinator. The ratio between components of floral female and male functions within the orchid population suggested that the much elongated operative male floral parts result from strong and progressively extreme sex-specific selection for acquiring mates via hawk-moths. By far the most frequent flower-visitors of C. uniflora at the study site were long-tongued nectar thieving hawk-moths whose relative abundance probably reflected faunal imbalance caused by the destruction of nearby moth foraging habitats through deforestation. 相似文献
107.
OXYGEN RELATIONS OF THE ROOT NODULES OF ALNUS RUBRA BONG. 总被引:2,自引:1,他引:1
108.
CORINNE RIVASSEAU MYRIAM SEEMANN ANNE-MARIE BOISSON PETER STREB ELISABETH GOUT ROLAND DOUCE MICHEL ROHMER & RICHARD BLIGNY 《Plant, cell & environment》2009,32(1):82-92
Metabolic profiling using phosphorus nuclear magnetic resonance (31 P-NMR) revealed that the leaves of different herbs and trees accumulate 2- C -methyl- d -erythritol 2,4-cyclodiphosphate (MEcDP), an intermediate of the methylerythritol 4-phosphate (MEP) pathway, during bright and hot days. In spinach ( Spinacia oleracea L.) leaves, its accumulation closely depended on irradiance and temperature. MEcDP was the only 31 P-NMR-detected MEP pathway intermediate. It remained in chloroplasts and was a sink for phosphate. The accumulation of MEcDP suggested that its conversion rate into 4-hydroxy-3-methylbut-2-enyl diphosphate, catalysed by ( E )-4-hydroxy-3-methylbut-2-enyl diphosphate synthase (GcpE), was limiting under oxidative stress. Indeed, O2 and ROS produced by photosynthesis damage this O2 -hypersensitive [4Fe-4S]-protein. Nevertheless, as isoprenoid synthesis was not inhibited, damages were supposed to be continuously repaired. On the contrary, in the presence of cadmium that reinforced MEcDP accumulation, the MEP pathway was blocked. In vitro studies showed that Cd2+ does not react directly with fully assembled GcpE, but interferes with its reconstitution from recombinant GcpE apoprotein and prosthetic group. Our results suggest that MEcDP accumulation in leaves may originate from both GcpE sensitivity to oxidative environment and limitations of its repair. We propose a model wherein GcpE turnover represents a bottleneck of the MEP pathway in plant leaves simultaneously exposed to high irradiance and hot temperature. 相似文献
109.
110.
ANNETTE MENZEL TIM H. SPARKS NICOLE ESTRELLA ELISABETH KOCH ANTO AASA REIN AHAS KERSTIN ALM‐KÜBLER PETER BISSOLLI OL'GA BRASLAVSK AGRITA BRIEDE FRANK M. CHMIELEWSKI ZALIKA CREPINSEK YANNICK CURNEL SL
G DAHL CLAUDIO DEFILA ALISON DONNELLY YOLANDA FILELLA KATARZYNA JATCZAK FINN MGE ANTONIO MESTRE
YVIND NORDLI JOSEP PE
UELAS PENTTI PIRINEN VIERA REMIOV HELFRIED SCHEIFINGER MARTIN STRIZ ANDREJA SUSNIK ARNOLD J. H. VAN VLIET FRANS‐EMIL WIELGOLASKI SUSANNE ZACH ANA ZUST 《Global Change Biology》2006,12(10):1969-1976
Global climate change impacts can already be tracked in many physical and biological systems; in particular, terrestrial ecosystems provide a consistent picture of observed changes. One of the preferred indicators is phenology, the science of natural recurring events, as their recorded dates provide a high-temporal resolution of ongoing changes. Thus, numerous analyses have demonstrated an earlier onset of spring events for mid and higher latitudes and a lengthening of the growing season. However, published single-site or single-species studies are particularly open to suspicion of being biased towards predominantly reporting climate change-induced impacts. No comprehensive study or meta-analysis has so far examined the possible lack of evidence for changes or shifts at sites where no temperature change is observed. We used an enormous systematic phenological network data set of more than 125 000 observational series of 542 plant and 19 animal species in 21 European countries (1971–2000). Our results showed that 78% of all leafing, flowering and fruiting records advanced (30% significantly) and only 3% were significantly delayed, whereas the signal of leaf colouring/fall is ambiguous. We conclude that previously published results of phenological changes were not biased by reporting or publication predisposition: the average advance of spring/summer was 2.5 days decade−1 in Europe. Our analysis of 254 mean national time series undoubtedly demonstrates that species' phenology is responsive to temperature of the preceding months (mean advance of spring/summer by 2.5 days°C−1 , delay of leaf colouring and fall by 1.0 day°C−1 ). The pattern of observed change in spring efficiently matches measured national warming across 19 European countries (correlation coefficient r =−0.69, P <0.001). 相似文献