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91.
Rhizome transition to storage organ is under phytochrome control in lotus <Emphasis Type="Italic">(Nelumbo nucifera)</Emphasis> 总被引:1,自引:0,他引:1
We examined photoperiodic response of lotus (Nelumbo
nucifera) rhizome morphogenesis (its transition to a storage organ) by using seed-derived plants. Rhizome enlargement (increase in
girth) was brought about under 8, 10 and 12 h photoperiods, whereas the rhizomes elongated under 13 and 14 h photoperiods.
Rhizomes elongated under 14 h light regimes supplied as 8 h of natural light plus 6 h supplemental hours of white, yellow
or red light, but similar treatments with supplemental blue, green or far red light, caused enlargement in girth of the rhizomes.
A 2 h interruption of the night with white, yellow or red light, in plants entrained to 8 h photoperiod brought rhizome elongation,
whereas 2 h-blue, green or far red light night breaks still resulted in rhizome increase in girth. The inhibitory effect of
a red (R) light night break on rhizome increase in girth was reversed by a far-red (FR) light given immediately afterwards.
Irradiation with R/FR/R inhibited the rhizome increase in girth. FR light irradiation following R/FR/R irradiation cancelled
the effect of the last R light irradiation. It was demonstrated that the critical photoperiod for rhizome transition to storage
organ is between 12 and 13 h photoperiod. It was also evident that the optimal light quality range for interruption of dark
period (night break) is between yellow and red light and that a R/FR reversible reaction is observed. From these results,
we propose that phytochrome plays an important role in photoperiodic response of rhizome increase in girth in lotus. This
is the first report on phytochrome-dependent morphogenesis of storage organs in rhizomous plants. 相似文献
92.
研究了荷叶铁线蕨(Adiantum reniforme var.sinense)的不同贮藏时间与培养条件对其配子体发育和孢子体形成的影响,结果表明:荷叶铁线蕨孢子为不含叶绿素孢子,在室温下保存5年以上时间依然具有活力,但不同的贮藏时间对配子体和孢子体的形成具有显著的影响。其中,室温贮藏7d的配子体形成的时间为29d,而贮藏5年的为38d;贮藏7d的孢子体形成的时间为96d,贮藏4个月的为105d。在培养室[(25±1)℃恒温和每天2000~2500lx12h光照]沙基质中,从孢子播种到形成孢子体时间最短,为87d;沙基质比腐殖土更利于孢子体的形成;配子体密度在不超过3株/cm2的情况下,密度越高越有利于孢子体的形成。 相似文献
93.
Mycoplasma contamination affects many different aspects of cell culturing, resulting in unreliable experimental results and
potentially harmful biological products. Therefore, the specificity, sensitivity, and reliability of detecting mycoplasma
contamination are important aspects of quality control in biotechnological products. In this study, Mycoplasma hyorhinis was adopted as a model strain to evaluate the effects of storage on the viability of Mycoplasma species in cell culture samples.
Medium X was compared with conventional media 243 and 988 for the ability to detect M. hyorhinis. The 101 CFU/ml of M. hyorhinis was inoculated into medium X prepared using the same lots of components and preserved for 7 d, 1 mo, and 2 mo. M. hyorhinis grew readily and typically on agar plates prepared within 1 mo. The viable mycoplasmas in samples containing different initial
titers (101 and 106 CFU/ml) after storage at 4° C and −30° C were analyzed. During storage, viable organisms were found with little or no reduction
in titers after storage for 8 wk at −30° C under aerobic and anaerobic conditions. A reduction in titers of 3 log10 occurred
after 4 wk storage for high-dose cultures (106 CFU/ml) at 4° C. The titers of viable organisms were diminished over 8 wk at 4° C under aerobic and anaerobic conditions. 相似文献
94.
AIMS: The fungus Meira geulakonigii has been shown to reduce populations of citrus rust mite (CRM; Phyllocoptruta oleivora) on citrus leaves and fruits, in both the field and laboratory. However, attempts to isolate the fungus from leaves and fruits have been unsuccessful. The aims of this study were therefore to determine whether M. geulakonigii is a citrus endophyte, and to assess possible mechanisms involved in its mite-antagonist activity. METHODS AND RESULTS: A quantitative real-time PCR and regular PCR approaches were developed to detect M. geulakonigii in both the field and laboratory. The fungus was detected throughout. Different methods revealed that M. geulakonigii is an endophyte, which colonizes both the peel of grapefruits. Applications of conidia protected the grapefruits against CRM, and fungal secretions extracted from growth media caused 100% CRM mortality. CONCLUSIONS: Meira geulakonigii is a beneficial endophyte of grapefruits that colonizes the fruit's peel, and protects it from CRM. SIGNIFICANCE AND IMPACT OF THE STUDY: Findings from this study demonstrate the endophytic nature of M. geulakonigii in its interaction with grapefruits. In addition, a molecular approach was developed to specifically detect the fungus inside the grapefruit peel. This approach can be used to assess the natural occurrence of M. geulakonigii in grapefruit. 相似文献
95.
Choi YJ Lee EM Park JM Lee KM Han SH Kim JK Lee SH Song HJ Choi MS Kim IS Park KH Jang WJ 《Microbiology and immunology》2007,51(3):307-312
This study revealed the presence of various rickettsial agents in mites from wild rodents collected in Southern Jeolla Province, Korea, by nested polymerase chain reaction (PCR) and sequence analysis of a partial citrate synthase and rickettsia outer membrane protein B genes. Rickettsial agents closely related to the Rickettsia species TwKM02, R. australis, and the Rickettsia species Cf15 were successfully identified in this study, for the first time in Korea, and R. japonica, R. akari, R. conorii, R. felis, and R. typhi were also detected, as previously described. The data presented in this paper extend knowledge on the geographic distribution of SFG rickettsiae in eastern Asia and it may necessary to consider the role of mites in rickettsial transmission. 相似文献
96.
Andrew Fairbairn Danièle Martinoli Ann Butler Gordon Hillman 《Vegetation History and Archaeobotany》2007,16(6):467-479
Full analysis of eight seed samples collected in the 1960's excavations at Neolithic Çatalhöyük East, Turkey, is presented. Detailed investigation of the composition and context of the samples suggests that the Neolithic population collected, processed and stored seeds from Capsella sp. and Descurainia sp. (wild crucifers) for food use. In addition seeds of Vicia/Lathyrus sp. (wild vetch), Helianthemum spp. and Taeniatherum caput-medusae mixed with Eremopyrum type (grasses) were also found, some of which may have been used for food or other purposes. The analysis demonstrates that wild seed exploitation was a regular part of subsistence practice alongside the economic staple of crop production, and again demonstrates how diverse plant use practices were at the site. 相似文献
97.
Mosaic cycles in agricultural landscapes of Northwest Europe 总被引:2,自引:0,他引:2
Michael Kleyer Robert Biedermann Klaus Henle Elisabeth Obermaier Hans-Joachim Poethke Peter Poschlod Boris Schrder Josef Settele Doris Vetterlein 《Basic and Applied Ecology》2007,8(4):295-309
Mosaic cycles were originally understood as cyclical regeneration phases in forests. In this review, we shall examine how far the concept can be extended towards cyclical mosaics of habitat quality in patterned landscapes as a special case of ‘dynamic landscapes’. We will concentrate on habitats and plants in European temperate agricultural landscapes and grasslands in particular. Mosaic cycles of habitat quality are characterised by spatiotemporal shifts between disturbance and secondary succession. We found evidence for mosaic cycles in traditional agricultural systems, modern crop farming, and in recent conservation management. The relevant disturbance parameters to describe land-use drivers of mosaic cycles are spatial extent, frequency, and magnitude (biomass loss). Land-use-related drivers are usually regular and deterministic in space and time, with the exception of year-round grazing by free-ranging large herbivores. Fluctuating soil resources such as water and nutrients in interaction with climate variability add a stochastic component to these (land-use-related) drivers. The proportion of deterministic and stochastic components and their autocorrelation in time and space divides purely deterministic mosaic cycles from purely stochastic dynamic landscapes. In a second part, we briefly review plant life-history traits that may facilitate survival of plants in mosaic cycles of habitat quality. Theoretical studies emphasise (i) dispersal functions for extinction and recolonisation processes of metapopulations, (ii) storage effects as a component of buffered population growth in response to temporal fluctuations of habitat quality, and (iii) competitive ability in metacommunities. We propose a simple scheme relating these functions to the temporal and spatial correlation of patterned landscapes. There are only a very limited number of field studies available that give some support for the proposed scheme. We provide perspectives for further research in this field. 相似文献
98.
We examined the impact of ploughing on soil seed banks of plant communities living in temporary marshes located in agricultural
fields. The quantity, quality and vertical distribution of seeds were quantified under ploughed or unploughed treatment at
community level. We also focussed on a typical semi-aquatic species, Damasonium alisma, to investigate the impact of ploughing at population level. We used two complementary techniques to study seed banks: hand
sorting and seedling emergence. We found that species richness of seeds, seed abundance and germination ability were strongly
affected by ploughing at community level. Concerning D. alisma, most of the seeds (56%) were stored in the two deepest soil layers among the four considered in ploughed pools. Moreover,
the germination rate was higher for buried seeds (84%) than for seeds collected at the surface (33.6%). These patterns were
almost inverted in unploughed pools. Our results agree with the temporal storage effect generally suggested to describe the
seed bank property of plant communities. But in addition, we showed that ploughing induces a spatial storage effect in accumulating
species and individuals in the seed banks that favourably influence community dynamics. We conclude that, in contrast to what
is usually thought, ploughing disturbance can be of benefit for such ephemeral wetland vegetation. 相似文献
99.
The Basidiomycotine fungi Meira geulakonigii, Meira argovae and Acaromyces ingoldii were assayed in the laboratory against five species of herbivorous mites: Phyllocoptruta oleivora (Eriophyidae), Panonychus
citri, Eutetranychus
orientalis, Tetranychus
urticae and Tetranychus
cinnabarinus (all four Tetranychidae). All fungi caused significantly high mortality rates (as compared to controls) after 14 days, some
after 1 week. Phyllocoptruta oleivora was the most susceptible, showing >80% mortality even after 1 week. In a field trial, grapefruits sprayed either once a month
or once a season with M. geulakonigii had significantly fewer P. oleivora and less damage than unsprayed fruit. These results suggest that M. geulakonigii may protect grapefruits against the injurious P. oleivora. 相似文献
100.
Host shifts are a key mechanism of parasite evolution and responsible for the emergence of many economically important pathogens. Varroa destructor has been a major factor in global honeybee (Apis mellifera) declines since shifting hosts from the Asian honeybee (Apis cerana) > 50 years ago. Until recently, only two haplotypes of V. destructor (Korea and Japan) had successfully host shifted to A. mellifera. In 2008, the sister species V. jacobsoni was found for the first time parasitizing A. mellifera in Papua New Guinea (PNG). This recent host shift presents a serious threat to world apiculture but also provides the opportunity to examine host shifting in this system. We used 12 microsatellites to compare genetic variation of V. jacobsoni on A. mellifera in PNG with mites on A. cerana in both PNG and surrounding regions. We identified two distinct lineages of V. jacobsoni reproducing on A. mellifera in PNG. Our analysis indicated independent host shift events have occurred through small numbers of mites shifting from local A. cerana populations. Additional lineages were found in the neighbouring Papua and Solomon Islands that had partially host shifted to A. mellifera, that is producing immature offspring on drone brood only. These mites were likely in transition to full colonization of A. mellifera. Significant population structure between mites on the different hosts suggested host shifted V. jacobsoni populations may not still reproduce on A. cerana, although limited gene flow may exist. Our studies provide further insight into parasite host shift evolution and help characterize this new Varroa mite threat to A. mellifera worldwide. 相似文献