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排序方式: 共有271条查询结果,搜索用时 31 毫秒
111.
Measurement of bacterivory by protists in open ocean waters 总被引:3,自引:1,他引:2
112.
Taxonomy and ecology of the phytoplankton of Lake Fidler and Sulphide Pool,meromictic Tasmanian lakes 总被引:2,自引:2,他引:0
A floristic list of 89 freshwater phytoplanktonic algae occurring in two neighbouring, dystrophic, meromictic Tasmanian lakes
is given. In both lakes the preponderance of desmids and phytoflagellates, especially chrysophytes, is a characteristic in
keeping with their dystrophic nature. All the alga must be adapted to low levels of red light and some habitually inhabit
crepuscular depths rather than executing diel vertical migrations such as happens in many dystrophic waters. Floristic differences
between the two lakes are related to morphometric differences and the degree of entrainment of tychoplankton. The photosynthetic
biomass of both lakes is predominantly monimolimnetic, made up of few species. The floristically-rich mixolimnion contributes
little to biomass. The ecology of the dystrophic flora is discussed in relation to the special circumstances of meromixis. 相似文献
113.
Michael Krämer Manfred Baumgärtner Martin Bender Ralf Conrad 《FEMS microbiology letters》1990,73(4):345-350
Abstract The methanotrophs Methylomonas angile (type I) and Methylosinus trichosporium (type II) produced nitrite, nitrate and N2 O during growth on methane, apparently by heterotrophic nitrification of ammonium. The methanotrophs were also able to consume NO but did not produce it. After incubation of soil from a drained paddy field in the presence of CH4 the numbers of methanotrophs increased from 105 to 107 per gram dry weigth. The thus enriched soil showed increased rates of NO consumption while rates of NO production did not change. 相似文献
114.
Some size relationships in phytoflagellate motility 总被引:5,自引:5,他引:0
Ulrich Sommer 《Hydrobiologia》1988,161(1):125-131
Data from the literature are used to assess some hypothesised adaptive advantages of the flagellate life form among phytoplankton. Possible advantages include increased nutrient uptake by movement through a homogeneous medium as opposed to exploitation of spatial hetrogeneity of the environment. Maximal migrational amplitudes and maximal swimming velocities of phytoflagellates were compared to body size. Both were found to increase with size. Relative amplitudes and relative velocities, however, were found to decrease with size. Hydrophysical considerations show that additional gain of nutrients by swimming through a homogeneous medium is only minimal for small flagellates at their attainable swimming velocities. It is suggested that exploitation of environmental heterogeneity in nutrient distribution may be one of the most important advantages for flagellates over coccoid algae. 相似文献
115.
The Morphology,Ultrastructure and SSU rRNA Gene Sequence of a New Freshwater Flagellate,Neobodo borokensis n. sp. (Kinetoplastea,Excavata) 下载免费PDF全文
Denis V. Tikhonenkov Jan Janouškovec Patrick J. Keeling Alexander P. Mylnikov 《The Journal of eukaryotic microbiology》2016,63(2):220-232
A small free‐living freshwater bacteriotrophic flagellate Neobodo borokensis n. sp. was investigated by electron microscopy and analysis of its SSU ribosomal RNA gene. This protist has paraxonemal rods of typical bodonid structure in the flagella, mastigonemes on the proximal part of the posterior flagellum, two nearly parallel basal bodies, a compact kinetoplast, and discoid mitochondrial cristae. The flagellar pocket is supported by three microtubular roots (R1, R2 and R3) originating from the kinetosome. The cytopharynx is supported by the root R2, a microtubular prism, cytopharynx associated additional microtubules (CMT) and cytostome associated microtubules (FAS) bands. Symbiotic bacteria and small glycosomes were found in the cytoplasm. Cysts have not been found. The flagellate prefers freshwater habitats, but tolerates salinity up to 3–4‰. The overall morphological and ultrastructural features confirm that N. borokensis represents a new species of the genus Neobodo. Phylogenetic analysis of SSU rRNA genes is congruent with the ultrastructure and strongly supports the close relationship of N. borokensis to Neobodo saliens, N. designis, Actuariola, and a misidentified sequence of “Bodo curvifilus” within the class Kinetoplastea. 相似文献
116.
杭州西湖水体中异养细菌生长的限制因子 总被引:3,自引:0,他引:3
通过添加不同营养盐类的纯种和自然培养试验,对异养细菌生长的限制因子进行了研究.结果表明,生物可利用的有机碳是主要的限制性营养因子,而氮源和磷源的影响相对较小;湖水的高pH、丰富的藻类和浮游动物生物量也制约了异养细菌的生长.此外还发现,在自然水体中添加0.5%葡萄糖后,一些自生固氮细菌得到富集;添加C+N+P后,有大量霉菌生长,添加0.01%牛肉膏后,假单胞菌属(PSeu-domonas)细菌由原来的30%提高到57%;湖水进行实验室培养时细菌的最大生长量可达10^5个·ml^-1。 相似文献
117.
Biomass and lipid productivities of Chlorella vulgaris under different growth conditions were investigated. While autotrophic growth did provide higher cellular lipid content (38%),
the lipid productivity was much lower compared with those from heterotrophic growth with acetate, glucose, or glycerol. Optimal
cell growth (2 g l−1) and lipid productivity (54 mg l−1 day−1) were attained using glucose at 1% (w/v) whereas higher concentrations were inhibitory. Growth of C. vulgaris on glycerol had a similar dose effects as those from glucose. Overall, C. vulgaris is mixotrophic. 相似文献
118.
Costs of reproduction in circumpolar <Emphasis Type="Italic">Parnassia palustris</Emphasis> L. in light of global warming 总被引:1,自引:0,他引:1
In frequently burnt savannas, saplings face the formidable challenge of both recovering from, and eventually growing tall
enough to escape from, frequent fire damage. The aim of this study was to explore how saplings allocate carbon to achieve
these ends through carbon partitioning, storage and remobilization. Lignotuber total non-structural carbohydrate (TNC) concentrations
and δ13C values of Acacia karroo (Fabaceae; Mimosoideae) were determined in plants from two different juvenile stages. These were one year after a fire when
the plant consisted of numerous leafy shoots or coppices (“coppicing” stage), and three years after a fire when the plant
consisted of one pole-like stem (“Gulliver” stage). Gulliver lignotubers were found to have significantly larger TNC pools
(150 g vs. 97 g) and larger TNC concentrations (33% vs. 24%, w/w) than coppice lignotubers showing that post-coppice Gullivers
recharged TNC in the lignotuber. δ13C values from the stems of plants in the Gulliver stage were significantly enriched (>1‰) in 13C compared to both coppicing (P < 0.01) and adult (P < 0.05) plants. Changes in both the amount of stored carbon and in the δ13C values indicated dependence on stored carbon reserves, and partially heterotrophic growth for initial resprouting. The plants
appeared to use both current photosynthate and stored carbon reserves for growth of the Gulliver stem. The use of stored carbon
is hypothesized to promote fast stem growth rates to a height where saplings escape fire injury. 相似文献
119.
Brugerolle G 《The Journal of eukaryotic microbiology》2006,53(4):246-259
Cytological features observed using light, immunofluorescence, and electron microscopy of the type species Holomastigotes elongatum were compared with Holomastigotes lanceolata and to Holomastigotes flexuosum n. sp. The comparison was extended to Spirotrichonymphella pudibunda and to Uteronympha africana n. gen. n. sp., in order to present the common features of the Holomastigotidae (Spirotrichonymphida). All these species have anterior basal bodies bearing microfibrillar or striated rootlets that are reduced or absent posterior to the nucleus. An axostylar trunk is present in Holomastigotes elongatum and Holomastigotes lanceolata, whereas the axostylar microtubules do not extend posterior to the nucleus in Holomastigotes flexuosum, Spirotrichonymphella, and Uteronympha. Uteronympha africana has specific features, such as a transverse plaque inside the columella from which arise microtubules capping the nucleus, and as in Spirotrichonympha the striated lamina is present all along the flagellar lines. Uteronympha africana has ability to endocytose wood particles in addition to the osmotrophic feeding that occurs in all the Holomastigotidae. 相似文献
120.