全文获取类型
收费全文 | 208篇 |
免费 | 19篇 |
国内免费 | 1篇 |
出版年
2023年 | 1篇 |
2022年 | 1篇 |
2021年 | 1篇 |
2020年 | 2篇 |
2019年 | 3篇 |
2018年 | 2篇 |
2017年 | 2篇 |
2016年 | 5篇 |
2015年 | 9篇 |
2014年 | 12篇 |
2013年 | 12篇 |
2012年 | 8篇 |
2011年 | 13篇 |
2010年 | 15篇 |
2009年 | 7篇 |
2008年 | 8篇 |
2007年 | 11篇 |
2006年 | 5篇 |
2005年 | 7篇 |
2004年 | 6篇 |
2003年 | 4篇 |
2002年 | 8篇 |
2001年 | 6篇 |
2000年 | 10篇 |
1999年 | 7篇 |
1998年 | 5篇 |
1997年 | 3篇 |
1996年 | 3篇 |
1995年 | 5篇 |
1994年 | 3篇 |
1993年 | 2篇 |
1992年 | 1篇 |
1991年 | 2篇 |
1990年 | 5篇 |
1989年 | 8篇 |
1988年 | 4篇 |
1987年 | 5篇 |
1986年 | 3篇 |
1983年 | 2篇 |
1982年 | 1篇 |
1980年 | 1篇 |
1979年 | 3篇 |
1976年 | 2篇 |
1975年 | 2篇 |
1973年 | 2篇 |
1969年 | 1篇 |
排序方式: 共有228条查询结果,搜索用时 15 毫秒
51.
DNA of eight endosymbiotic dinoflagellates (zooxanthellae) from seven different host species has been analyzed as to its thermal characteristics and base composition by means of spectrophotometry and high performance liquid chromatography. All algae under investigation contain both methylcytosine and hydroxymethyluracil in addition to the bases typical of nuclear DNA. As a result, melting temperatures are decreased, suggesting lower contents of guanine plus cytosine than actually present. True percentages of guanine plus cytosine plus methylcytosine range from about 43 to 54 mol%. They are unique for the symbionts from different hosts, indicating phylogenetic separation of the taxa comparised within the genus Symbiodinium.Abbreviations dA
deoxyadenosine
- dC
deoxycytidine
- dG
deoxyguanosine
- dT
deoxythymidine
- m5dC
5-methyldeoxycytidine
- hmdU
5-hydroxymethyldeoxyuridine
- rC
ribocytidine
- Br8G
bromine-80guanosine
- A
adenine
- C
cytosine
- G
guanine
- T
thymine
- m5C
5-methylcytosine
- hmU
5-hydroxymethyluracil
- G+C
guanine plus cytosine plus 5-methylcytosine
- HPLC
high performance liquid chromatography
-
T
m
temperature at the midpoint of hyperchromic shift
- CTAB
N-cetyl-N,N,N-trimethyl-ammonium bromide
- EDTA
ethylenediamine-tetraacetic acid, disodium salt
- TRIS
tris-(hydroxymethyl)-aminomethane
- 1×SSC
standard saline citrate (0.15 M NaCl+0.015 M trisodium citrate, pH 7.0) 相似文献
52.
53.
Magnus Huss Jennifer G. Howeth Julia I. Osterman David M. Post 《Proceedings. Biological sciences / The Royal Society》2014,281(1787)
Evolutionary diversification within consumer species may generate selection on local ecological communities, affecting prey community structure. However, the extent to which this niche construction can propagate across food webs and shape trait variation in competing species is unknown. Here, we tested whether niche construction by different life-history variants of the planktivorous fish alewife (Alosa pseudoharengus) can drive phenotypic divergence and resource use in the competing species bluegill (Lepomis macrochirus). Using a combination of common garden experiments and a comparative field study, we found that bluegill from landlocked alewife lakes grew relatively better when fed small than large zooplankton, had gill rakers better adapted for feeding on small-bodied prey and selected smaller zooplankton compared with bluegill from lakes with anadromous or no alewife. Observed shifts in bluegill foraging traits in lakes with landlocked alewife parallel those in alewife, suggesting interspecific competition leading to parallel phenotypic changes rather than to divergence (which is commonly predicted). Our findings suggest that species may be locally adapted to prey communities structured by different life-history variants of a competing dominant species. 相似文献
54.
The genetic relationships of nine strains of Chlorella saccharophila were determined by DNA hybridization techniques. Four strains are closely related to the type strain 211-9a and one strain seems to be moderately related, whereas the taxonomic position of the remaining three strains is not clear. C. saccharophila, like C. sorokiniana, is another species of Chlorella containing strains which are heterogeneous in their overall DNA base sequence and partly also in morphological, biochemical and physiological characters. 相似文献
55.
Blasiole B Canfield VA Vollrath MA Huss D Mohideen MA Dickman JD Cheng KC Fekete DM Levenson R 《Developmental biology》2006,294(1):148-160
We have investigated the role of Na,K-ATPase genes in zebrafish ear development. Six Na,K-ATPase genes are differentially expressed in the developing zebrafish inner ear. Antisense morpholino knockdown of Na,K-ATPase alpha1a.1 expression blocked formation of otoliths. This effect was phenocopied by treatment of embryos with ouabain, an inhibitor of Na,K-ATPase activity. The otolith defect produced by morpholinos was rescued by microinjection of zebrafish alpha1a.1 or rat alpha1 mRNA, while the ouabain-induced defect was rescued by expression of ouabain-resistant zebrafish alpha1a.1 or rat alpha1 mRNA. Knockdown of a second zebrafish alpha subunit, alpha1a.2, disrupted development of the semicircular canals. Knockdown of Na,K-ATPase beta2b expression also caused an otolith defect, suggesting that the beta2b subunit partners with the alpha1a.1 subunit to form a Na,K-ATPase required for otolith formation. These results reveal novel roles for Na,K-ATPase genes in vestibular system development and indicate that different isoforms play distinct functional roles in formation of inner ear structures. Our results highlight zebrafish gene knockdown-mRNA rescue as an approach that can be used to dissect the functional properties of zebrafish and mammalian Na,K-ATPase genes. 相似文献
56.
The processes of CO2 acquisition were characterized for the acid‐tolerant, free‐living chlorophyte alga, CPCC 508. rDNA data indicate an affiliation to the genus Coccomyxa, but distinct from other known members of the genus. The alga grows over a wide range of pH from 3.0 to 9.0. External carbonic anhydrase (CA) was detected in cells grown above pH 5, with the activity increasing marginally from pH 7 to 9, but most of the CA activity was internal. The capacity for HCO3? uptake of cells treated with the CA inhibitor acetazolamide (AZA), was investigated by comparing the calculated rate of uncatalyzed CO2 formation with the rate of photosynthesis. Active bicarbonate transport occurred in cells grown in media above pH 7.0. Monitoring CO2 uptake and O2 evolution by membrane‐inlet mass spectrometry demonstrated that air‐grown cells reduced the CO2 concentration in the medium to an equilibrium concentration of 15 μM, but AZA‐treated cells caused a drop in extracellular CO2 concentration to a compensation concentration of 27 μM at pH 8.0. CO2‐pulsing experiments with cells in the light indicated that the cells do not actively take up CO2. An internal pool of unfixed inorganic carbon was not detected at the CO2 compensation concentration, probably because of the lack of active CO2 uptake, but was detectable at times before compensation point was reached. These results indicate that this free‐living Coccomyxa possesses a CO2‐concentrating mechanism (CCM) due to an active bicarbonate‐uptake system, unlike the Coccomyxa sp. occurring in symbiotic association with lichens. 相似文献
57.
Ramularia collo-cygni causes leaf spots on barley (Hordeum vulgare), a disease of growing economical importance. Scanning electron microscopy was used to study the life cycle of the fungus
on barley during the vegetation period and in winter. The infectious stage started with conidium germination on the surface
and the penetration into the leaf via the stomatal pore where the hyphae grew within the cells that became necrotic. The conidiophores
emerged through the stomatal pore. On older leaves, however, they frequently emerged apart from it and the results suggested
a pushing apart of adjacent cell walls of the epidermal cells. An assessment of the amount of conidium formation of one heavily
infested barley plant resulted in 4.05 × 106 conidia per plant. For the first time, conidiophores, conidium production and germination of conidia were also observed in
winter on barley and on maize leaves. 相似文献
58.
Cannibalistic interactions generally depend on the size relationship between cannibals and victims. In many populations, a large enough size variation to allow for cannibalism may not only develop among age‐cohorts but also within cohorts. We studied the implications of variation in hatching period length and initial cohort size for the emergence of cannibalism and bimodal size distributions within animal cohorts using a physiologically structured population model. We found that the development of size bimodality was critically dependent on hatching period length, victim density and the presence of a feedback via shared resources. Cannibals only gained enough energy from cannibalism to accelerate in growth when victim density was high relative to cannibal density at the onset of cannibalism. Furthermore, we found that the opportunity for early hatchers to initially feed on an unexploited resource increases the likelihood both for cannibalism to occur and size bimodality to develop. Once cannibals accelerated in growth relative to victims size bimodality, reduced victim numbers and relaxed resource competition resulted. Thus, in addition to that cannibals profited from cannibalism through energy extraction, their potential victims also benefited as the resource recovered due to cannibal thinning. To ensure recruitment success, it can be critical that a few individuals can accelerate in growth and reach a size large enough to escape size‐dependent predation and winter starvation. Hence, within‐cohort cannibalism may be a potentially important mechanism to explain recruitment variation especially for cannibalistic species in temperate climates with strong seasonality. However, the scope for size bimodality to develop as a result of cannibalism may be limited by low victim densities and size and food‐dependent growth rates. 相似文献
59.
Wieczorek H Huss M Merzendorfer H Reineke S Vitavska O Zeiske W 《Journal of bioenergetics and biomembranes》2003,35(4):359-366
The plasma membrane H+ V-ATPase from the midgut of larval Manduca sexta, commonly called the tobacco hornworm, is the sole energizer of epithelial ion transport in this tissue, being responsible for the alkalinization of the gut lumen up to a pH of more than 11 and for any active ion movement across the epithelium. This minireview deals with those topics of our recent research on this enzyme that may contribute novel aspects to the biochemistry and physiology of V-ATPases. Our research approaches include intramolecular aspects such as subunit topology and the inhibition by macrolide antibiotics, intermolecular aspects such as the hormonal regulation of V-ATPase biosynthesis and the interaction of the V-ATPase with the actin cytoskeleton, and supramolecular aspects such as the interactions of V-ATPase, K+/H+ antiporter, and ion channels, which all function as an ensemble in the transepithelial movement of potassium ions. 相似文献
60.
Volker AR Huss Claudia Ciniglia Paola Cennamo Salvatore Cozzolino Gabriele Pinto Antonino Pollio 《BMC evolutionary biology》2002,2(1):13-9