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101.
102.
103.
Storkey J Meyer S Still KS Leuschner C 《Proceedings. Biological sciences / The Royal Society》2012,279(1732):1421-1429
The impact of crop management and agricultural land use on the threat status of plants adapted to arable habitats was analysed using data from Red Lists of vascular plants assessed by national experts from 29 European countries. There was a positive relationship between national wheat yields and the numbers of rare, threatened or recently extinct arable plant species in each country. Variance in the relative proportions of species in different threat categories was significantly explained using a combination of fertilizer and herbicide use, with a greater percentage of the variance partitioned to fertilizers. Specialist species adapted to individual crops, such as flax, are among the most threatened. These species have declined across Europe in response to a reduction in the area grown for the crops on which they rely. The increased use of agro-chemicals, especially in central and northwestern Europe, has selected against a larger group of species adapted to habitats with intermediate fertility. There is an urgent need to implement successful conservation strategies to arrest the decline of this functionally distinct and increasingly threatened component of the European flora. 相似文献
104.
Argyris J Truco MJ Ochoa O Knapp SJ Still DW Lenssen GM Schut JW Michelmore RW Bradford KJ 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》2005,111(7):1365-1376
Seed and seedling traits related to germination and stand establishment are important in the production of cultivated lettuce
(Lactuca sativa L.). Six seed and seedling traits segregating in a L. sativa cv. Salinas x L. serriola recombinant inbred line population consisting of 103 F8 families revealed a total of 17 significant quantitative trait loci
(QTL) resulting from three seed production environments. Significant QTL were identified for germination in darkness, germination
at 25 and 35°C, median maximum temperature of germination, hypocotyl length at 72 h post-imbibition, and plant (seedling)
quality. Some QTL for germination and early seedling growth characteristics were co-located, suggestive of pleiotropic loci
regulating these traits. A single QTL (Htg6.1) described 25 and 23% of the total phenotypic variation for high temperature germination in California- and Netherlands-grown
populations, respectively, and was significant between 33 and 37°C. Additionally, Htg6.1 showed significant epistatic interactions with other Htg QTL and a consistent effect across all the three seed production environments. L. serriola alleles increased germination at these QTL. The estimate of narrow-sense heritability (h2) of Htg6.1 was 0.84, indicating potential for L. serriola as a source of germination thermotolerance for lettuce introgression programs. 相似文献
105.
Olfactory sensitivity in tsetse flies: a daily rhythm 总被引:3,自引:0,他引:3
The diurnal tsetse Glossina morsitans morsitans bites especially in early
morning and late afternoon; around midday feeding is at a low. In
laboratory apparatus that measures the amount of locomotion under constant
conditions over the photophase, the flies display a similar patterning of
activity levels. The profile of daily rhythms for G. morsitans reported in
the literature includes a number of motor and sensory motor systems that
fluctuate cophasically. Lacking is a study on the patterning of the senses'
response levels. In this paper we present the first instance of a daily
modulation in the sense of smell. We stimulated the antennae with
concentration series of host-derived odours and measured the spiking rate
of cells at different times during the photophase. The
concentration-response curves suggest that the sensitivity of antennal
olfactory cells flows in parallel with the other daily rhythms. This was
also reflected in electroantennograms (EAGs). The electroantennography was
extended to G. fuscipes fuscipes, whose level of spontaneous locomotor
activity--instead of following a U- shaped pattern--rises gradually over
the photophase. Again, the EAGs appeared to parallel the species' locomotor
activity. What we believe happens is that the organism tones down the
sensitivity of its odour receptors during periods of anticipated inactivity
for reasons of economy.
相似文献
106.
Jacob G. Kirkland Misty R. Peterson Christopher D. Still II Leo Brueggeman Namrita Dhillon Rohinton T. Kamakaka 《Molecular biology of the cell》2015,26(7):1395-1410
Heterochromatin formation and nuclear organization are important in gene regulation and genome fidelity. Proteins involved in gene silencing localize to sites of damage and some DNA repair proteins localize to heterochromatin, but the biological importance of these correlations remains unclear. In this study, we examined the role of double-strand-break repair proteins in gene silencing and nuclear organization. We find that the ATM kinase Tel1 and the proteins Mre11 and Esc2 can silence a reporter gene dependent on the Sir, as well as on other repair proteins. Furthermore, these proteins aid in the localization of silenced domains to specific compartments in the nucleus. We identify two distinct mechanisms for repair protein–mediated silencing—via direct and indirect interactions with Sir proteins, as well as by tethering loci to the nuclear periphery. This study reveals previously unknown interactions between repair proteins and silencing proteins and suggests insights into the mechanism underlying genome integrity. 相似文献
107.
EcoHealth - The widespread adoption and sustained use of modern cookstoves has the potential to reduce harmful effects to climate, health, and the well-being of approximately one-third of the... 相似文献
108.
A covariotide model explains apparent phylogenetic structure of oxygenic photosynthetic lineages 总被引:4,自引:13,他引:4
Lockhart PJ; Steel MA; Barbrook AC; Huson DH; Charleston MA; Howe CJ 《Molecular biology and evolution》1998,15(9):1183-1188
The aims of the work were (1) to develop statistical tests to identify
whether substitution takes place under a covariotide model in sequences
used for phylogenetic inference and (2) to determine the influence of
covariotide substitution on phylogenetic trees inferred for photosynthetic
and other organisms. (Covariotide and covarion models are ones in which
sites that are variable in some parts of the underlying tree are invariable
in others and vice versa.) Two tests were developed. The first was a
contingency test, and the second was an inequality test comparing the
expected number of variable sites in two groups with the observed number.
Application of these tests to 16S rDNA and tufA sequences from a range of
nonphotosynthetic prokaryotes and oxygenic photosynthetic prokaryotes and
eukaryotes suggests the occurrence of a covariotide mechanism. The degree
of support for partitioning of taxa in reconstructed trees involving these
organisms was determined in the presence or absence of sites showing
particular substitution patterns. This analysis showed that the support for
splits between (1) photosynthetic eukaryotes and prokaryotes and (2)
photosynthetic and nonphotosynthetic organisms could be accounted for by
patterns arising from covariotide substitution. We show that the additional
problem of compositional bias in sequence data needs to be considered in
the context of patterns of covariotide/covarion substitution. We argue that
while covariotide or covarion substitution may give rise to
phylogenetically informative patterns in sequence data, this may not always
be so.
相似文献
109.
110.
Dexamethasone was evaluated as a treatment for radiation-induced lung, kidney, liver, and spinal cord injuries in rats. One experimental group was partial-body-irradiated (22.5 Gy) with the head, femur, and exteriorized intestine shielded to prevent acute mortality. Other animals received local irradiation to the kidney (20 Gy), liver (25 Gy), or a 1-cm segment of cervical spinal cord (18 to 40 Gy). Following irradiation half of the animals in each radiation group were given drinking water containing 188 micrograms/liter of dexamethasone. Tests were done to assess kidney function (hematocrit, plasma urea nitrogen, ethylenediaminetetraacetic acid clearance), liver function (rose bengal clearance, plasma glutamic oxaloacetic acid transaminase), or spinal cord injury (paralysis). The effectiveness of dexamethasone in preventing radiation injury was tissue specific. Dexamethasone eliminated lethal pleural fluid accumulation after partial-body irradiation and delayed development of kidney dysfunction after local kidney irradiation. As a result, dexamethasone increased the median survival time from 63 to 150 days after partial-body irradiation and from 126 to 175 days after local kidney irradiation. After whole-liver irradiation, development of hepatic functional injury was retarded by dexamethasone treatment but without significantly changing survival time. Dexamethasone had no effect on spinal cord tolerance but significantly shortened the latent period between radiation and paralysis. 相似文献