全文获取类型
收费全文 | 763篇 |
免费 | 44篇 |
出版年
2023年 | 6篇 |
2022年 | 12篇 |
2021年 | 23篇 |
2020年 | 18篇 |
2019年 | 23篇 |
2018年 | 22篇 |
2017年 | 31篇 |
2016年 | 26篇 |
2015年 | 35篇 |
2014年 | 48篇 |
2013年 | 61篇 |
2012年 | 59篇 |
2011年 | 44篇 |
2010年 | 40篇 |
2009年 | 25篇 |
2008年 | 33篇 |
2007年 | 28篇 |
2006年 | 45篇 |
2005年 | 26篇 |
2004年 | 16篇 |
2003年 | 13篇 |
2002年 | 18篇 |
2001年 | 20篇 |
2000年 | 14篇 |
1999年 | 20篇 |
1998年 | 11篇 |
1997年 | 7篇 |
1996年 | 8篇 |
1995年 | 5篇 |
1994年 | 2篇 |
1993年 | 4篇 |
1992年 | 3篇 |
1990年 | 6篇 |
1988年 | 4篇 |
1987年 | 5篇 |
1986年 | 2篇 |
1985年 | 2篇 |
1982年 | 5篇 |
1981年 | 3篇 |
1980年 | 3篇 |
1979年 | 4篇 |
1978年 | 4篇 |
1977年 | 3篇 |
1975年 | 2篇 |
1974年 | 4篇 |
1973年 | 6篇 |
1970年 | 2篇 |
1967年 | 1篇 |
1965年 | 1篇 |
1934年 | 1篇 |
排序方式: 共有807条查询结果,搜索用时 15 毫秒
1.
Lusinete Aciole De Queiroz 《Mycopathologia》1973,51(4):307-314
A new species of the genusEndomycopsis is proposed. It was isolated from waste water, at Montevideo-Uruguay.By its morphological and biochemical proprieties it differs from allEndomycopsis previously described.
Este trabajo fue desarrollado en el Laboratorio de Micologia de la Facultad de Química de Montevideo, Uruguay y en uso de una beca de la Universidad Federal de Pernambuco para perfecciobamiento en el estudio de las levaduras. 相似文献
Este trabajo fue desarrollado en el Laboratorio de Micologia de la Facultad de Química de Montevideo, Uruguay y en uso de una beca de la Universidad Federal de Pernambuco para perfecciobamiento en el estudio de las levaduras. 相似文献
2.
Green callus obtained from leaves of the CAM-inducible plant Kalanchoe blossfeldiana cv. Montezuma has previously been shown to perform C3-type photosynthesis under 16-h days and to shift to crassulacean acid metabolism (CAM) under 9-h days. The utilization of photoperiodic regimes (i.e. night interruptions by 30 min red light) established that CAM induction in the callus was under the control of phytochrome, as shown by measurements of CAM criteria: phosphoenolpyruvate carboxylase activity and malic acid pools. Short-term responsiveness of the callus cells to phytochrome modulations by monochromatic radiations was also established by the rapid changes observed in the diameter of the callus-derived protoplasts. These results provide further evidence that whole plant correlations are not necessary for phytochrome operativity.Abbreviations CAM
crassulacean acid metabolism
- PAL
phenylalanine ammonia lyase (EC 4.3.1.5)
- PAR
photosynthetically active radiations
- PEPC
phosphoenolpyruvate carboxylase (EC 4.1.1. 31)
- Rubisco
ribulose 1,5 bisphosphate carboxylase (EC 4.1.1.39) 相似文献
3.
Lusinete Aciole de Queiroz 《Mycopathologia》1974,54(4):559-564
A new species of the genusEndomycopsis is proposed. It was isolated from wast water, at Montevideo-Uruguay.By its morphological and biochemical proprieties it differs from allEndomycopsis previously described.Este trabajo fue desarrollado en el Laboratorio de Micologia de la Facultad de Quimica de Montevideo, Uruguay y en uso de una beca de la Universidad Federal de Pernambuco para perfeccio bamiento en el estudo de las levaduras. 相似文献
4.
The effect of the plating medium on the recovery of nonsense suppressors in Saccharomyces cerevisiae 总被引:2,自引:0,他引:2
Clara Queiroz 《Biochemical genetics》1973,8(1):85-100
The recovery of nonsense suppressors in a strain of Saccharomyces cerevisiae carrying five ochre mutations, tr, hi, ly, ar, and ad, is affected by the plating medium. The highest frequency is observed on tryptophanless medium, while the lowest is observed on adenineless medium. Experiments showed that exogenous histidine inhibits suppressor expression and that exogenous adenine relieves this inhibition. In histidine-independent strains, mutation expression requires adenine. A model, based on the role of RNA in supersuppression and on the biosynthetic pathways of histidine and adenine, is proposed to account for the observed data. It cannot, however, account for the high frequency of suppressors on tryptophanless medium. The tentative conclusion is drawn either that mis-reading of the tryptophan nonsense codon by mutated tRNA is facilitated by the neighboring bases or that the type of acceptable amino acid is less rigorously limited in the mutated site of the tryptophan locus than in those of the other suppressible loci.This work was in part supported by the Calouste Gulbenkian Foundation and by the Medical Research Council (Grant No. G969/24/B). 相似文献
5.
Aristóteles Philippe Nunes Queiroz Maria Lúcia Góes Araújo Nigel E. Hussey Rosângela P. T. Lessa 《Journal of fish biology》2023,102(1):27-43
Understanding the ecological role of species with overlapping distributions is central to inform ecosystem management. Here we describe the diet, trophic level and habitat use of three sympatric stingrays, Hypanus guttatus, H. marianae and H. berthalutzae, through combined stomach content and stable isotope (δ13C and δ15N) analyses. Our integrated approach revealed that H. guttatus is a mesopredator that feeds on a diverse diet of benthic and epibenthic marine and estuarine organisms, principally bivalve molluscs, Alpheus shrimp and teleost fishes. Isotopic data supported movement of this species between marine and estuarine environments. H. berthalutzae is also a marine generalist feeder, but feeds primarily on teleost fishes and cephalopods, and consequently occupies a higher trophic level. In contrast, H. marianae is a mesopredator specialized on shrimps and polychaetas occurring only in the marine environment and occupying a low niche breadth. While niche overlap occurred, the three stingrays utilized the same prey resources at different rates and occupied distinct trophic niches, potentially limiting competition for resources and promoting coexistence. These combined data demonstrate that these three mesopredators perform different ecological roles in the ecosystems they occupy, limiting functional redundancy. 相似文献
6.
João Ricardo Sato Claudinei Eduardo Biazoli Ana Paula Arantes Bueno Arthur Caye Pedro Mario Pan Marcos Santoro Jessica Honorato-Mauer Giovanni Abrahão Salum Marcelo Queiroz Hoexter Rodrigo Affonseca Bressan Andrea Parolin Jackowski Euripedes Constantino Miguel Sintia Belangero Luis Augusto Rohde 《Genes, Brain & Behavior》2023,22(2):e12838
7.
Adaptive hypotheses based on interspecific comparisons can be tested by evaluating the context‐dependence of the behaviour of individual organisms. Drummond (Behaviour, 86, 1983, 1) categorized garter snake species (Thamnophis) as terrestrial–aquatic generalists or aquatic specialists based on diet and aquatic foraging behaviour. He hypothesized that the characteristic foraging behaviours of aquatic specialists – including frequent crawling on the underwater substrate and a high rate of underwater predatory strikes – are adaptations for feeding on relatively widely dispersed aquatic prey. Drummond's hypothesis based on interspecific comparisons suggests that individual snakes might change their foraging in the direction of aquatic specialist behaviour with an increase in water depth (which increases prey dispersion). I tested this prediction through laboratory observations of Mexican Pacific lowlands garter snakes (T. validus) feeding on minnows in shallow (2 cm) and deep (3–7 cm) water. Members of this species are appropriate subjects because they are ecologically intermediate between the generalists and aquatic specialists studied by Drummond, and thus might be expected to show more variation in aquatic foraging behaviour than those species. T. validus showed significantly higher frequencies of crawling on the underwater substrate and of underwater strikes in the deep water than in the shallow water; i.e. increased water depth shifted the behaviour of these snakes toward that of aquatic specialists, thus supporting Drummond's hypothesis. Individuals of an aquatic specialist species, the narrow‐headed garter snake (T. rufipunctatus), showed less pronounced changes in behaviour with increased water depth. Western ribbon snakes (T. proximus), which feed primarily at the land–water interface (and are expected to act like terrestrial–aquatic generalists), typically refused to feed in deep water. Interspecific differences in underwater visual acuity may underly the behavioural differences among the three species by determining whether changes in foraging behaviour with water depth are advantageous. Information on phylogenetic relationships suggests that the facultative behaviour of T. validus may represent an intermediate stage in the evolution of aquatic specialization. 相似文献
8.
An Ustilago maydis ergosterol biosynthesis mutant (A14) which is partially blocked in sterol 14alpha-demethylase (P45014DM) activity is described. This mutant accumulated the abnormal 14alpha-methyl sterols, eburicol, 14alpha-methylfecosterol, and obtusifoliol, along with significant amounts of ergosterol. Although the A14 mutant grew nearly as well as the wild type, it was impaired in cell extension growth, which indicated a dysfunction in apical cell wall synthesis. The mutant was also found to be hypersensitive to the azole fungicides penconazole and tebuconazole. 相似文献
9.
10.
Measurements of net CO2 exchange, malate accumulation, properties and capacity of phosphoenolpyruvate carboxylase (PEPC, EC 4.1.1.31) in leaves of different ages of two short-day dependent Crassulacean acid metabolism (CAM) plants (Kalanchoe blossfeldiana v. Poelln. Tom thumb and K. velutina Welw.) show that, in both species: a) young leaves from plants grown under long days display a CO2 exchange pattern typical of C3 plants; b) leaf aging promotes CAM under long-day conditions; c) short-day treatment induces CAM in young leaves to a higher degree than aging under long days; d) at least in K. blossfeldiana, the PEPC form developed with leaf aging under long days and the enzyme form synthetized de novo in young leaves grown under short days were shown to have similar properties. Short days also promote CAM in older leaves though at a lesser extent than in young leaves: The result is that this photoperiodic treatment increases the general level of CAM performance by the whole plant. The physiological meaning of the control of PEPC capacity by photoperiodism could be to afford a precisely timed seasonal increase in CAM potentiality, enabling the plant to immediately optimize its response to the onset of drought periods.Abbreviations CAM
Crassulacean acid metabolism
- PEP
phosphoenolpyruvate
- PEPC
phosphoenolpyruvate carboxylase (EC 4.1.1.31)
- LD
long day
- SD
short day 相似文献