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61.
62.
63.
Skirvin DJ Kravar-Garde L Reynolds K Jones J Mead A Fenlon J 《Bulletin of entomological research》2007,97(3):309-315
Two experiments were done to examine the predation of thrips, and the movement of Orius laevigatus Fieber and Neoseiulus cucumeris (Oudemans) in the presence and absence of two supplemental food sources, pollen and the fungus Trichoderma viride. The presence of pollen led to a 55% reduction in predation of the thrips by N. cucumeris and a 40% reduction in thrips predation by O. laevigatus, in experiments using single predators. The presence of fungus had no significant effect on thrips predation by either of the natural enemy species. Movement of the natural enemies was examined in a multiple predator experiment, and this showed that O. laevigatus was more likely to remain on the plant in the presence of thrips and when supplemental food, either pollen or fungus, was present. For N. cucumeris, there was no association between the presence of thrips and the mite, with the majority of the mites being found on the leaves where pollen was present. Although the single and multiple predator experiments were done at different times, the indications are that the predation rates of the N. cucumeris do not differ greatly between the two experiments, suggesting that there may be a potential interference effect between the mites, which is not present for O. laevigatus. The significance of these results for the use of supplemental food sources in biological control is discussed. 相似文献
64.
Leaf retention is important in transferring energy from riparian trees to stream food webs. Retention increases with geomorphic
complexity such as substrate coarseness, sinuosity, and the presence of debris dams. High discharge can reduce retention,
particularly when streams lack physical trapping features. Travertine formations, caused by calcium carbonate deposition,
can alter stream morphology. To date, however, we know of no study testing the effect of travertine on leaf retention. This
study capitalized on a river restoration project in Fossil Creek, Arizona, where water was returned to the channel after a
century of diversion. We examined how the fixed factors Flow (before and after restoration) and Morphology (travertine and
riffle-pool sites) affected leaf retention. Leaf retention was higher in sites where travertine forms barriers across the
river, relative to sites with riffle-pool morphology. Most leaves retained in travertine reaches were concentrated at the
bottom of pools formed between dams. Although flow restoration did not alter retention rates across all sites, it diminished
them at travertine sites, indicating an interaction between stream flow and morphology. We conclude that stream complexity
and leaf retention are enhanced by travertine deposition but that high discharge can reduce the retentive capacity of in-stream
structures.
Handling editor: Darren Ryder 相似文献
65.
Michael J. Arrowood Jan R. Mead Long-ti Xie Xiangdong You 《FEMS microbiology letters》1996,136(3):245-249
Abstract Despite the evaluation of over 100 antimicrobial drugs, the diarrheal disease cryptosporidiosis has remained refractory to treatment. We report the evaluation of five dinitroaniline herbicides including trifluralin, profluralin, nitralin, pendimethalin, and fluchloralin for anticryptosporidial activity in an in vitro cultivation model of Cryptosporidium parvum . All five compounds exhibited significant anticryptosporidial activities with no corresponding evidence of toxicity. The most active compound was pendimethalin with an IC50 of 0.19 μM while nitralin was the least active with an IC50 of 4.5 μM. These compounds should be evaluated further in an animal model of cryptosporidiosis. 相似文献
66.
Vinay Dhodda Ronald Godiska Jeffrey D. VanWye David Mead Rebecca Hochstein Lynne Sheets Sarah Vande Zande Chris Niebauer Douglas L. Crawford Marjorie F. Oleksiak 《PloS one》2010,5(9)
Background
ExCyto PCR cells provide a novel and cost effective means to amplify DNA transformed into competent bacterial cells. ExCyto PCR uses host E. coli with a chromosomally integrated gene encoding a thermostable DNA polymerase to accomplish robust, hot-start PCR amplification of cloned sequences without addition of exogenous enzyme.Results
Because the thermostable DNA polymerase is stably integrated into the bacterial chromosome, ExCyto cells can be transformed with a single plasmid or complex library, and then the expressed thermostable DNA polymerase can be used for PCR amplification. We demonstrate that ExCyto cells can be used to amplify DNA from different templates, plasmids with different copy numbers, and master mixes left on ice for up to two hours. Further, PCR amplification with ExCyto cells is comparable to amplification using commercial DNA polymerases. The ability to transform a bacterial strain and use the endogenously expressed protein for PCR has not previously been demonstrated.Conclusions
ExCyto PCR reduces pipetting and greatly increases throughput for screening EST, genomic, BAC, cDNA, or SNP libraries. This technique is also more economical than traditional PCR and thus broadly useful to scientists who utilize analysis of cloned DNAs in their research. 相似文献67.
Jere Mead 《Journal of applied physiology》2007,102(4):1708-9; discussion 1710
68.
A cytogenetic examination of spreaded cells of diapausing and early activated blastocysts obtained from 7 female western spotted skunks was performed. Mitosis was not observed in 1626 cells obtained from 9 diapausing blastocysts; however, 12 (1.5%) figures of diploid mitosis were seen in 851 cells from 5 early activated embryos. Diameter of the cell nuclei varied from 4 to 29 microm during diapause, and from 5 to 40 microm in activated blastocyst, and the heterogeneity in nuclear size was significantly different between diapausing and activated embryos (P<0.01). About 80% of nuclei from diapausing blastocysts measured 9 to 16 microm, whereas a similar percentage of nuclei from activated blastocysts ranged from 15 to 27 microm. Many enlarged nuclei exhibited morphological features characteristic of mammalian polytene (i.e. endopolyploid with polytenic organization of chromosomes) trophoblast cells. The number of silver stained nucleoli in all the nuclei did not exceed 2, which corresponds to the number of nucleolus organizers in the diploid karyotype in this species of skunk and suggests the polytene organization of chromosomes in enlarged nuclei. About 10% of large interphase nuclei were observed to undergo amitosis, i.e. direct division by constriction. The resulting nuclear fragments in diapausing blastocysts usually had normal morphology and active nucleoli. In activated embryos, nearly 15% of amitotically divided nuclei appeared to be dividing into fragments of unequal size, one of which had normal cell nuclear morphology and extremely large silver positive nucleoli, and the other fragment exhibited signs of cell death. We interpret these data as indicating that 1) amitotic division of trophoblast endopolyploid cell nuclei in the skunk blastocysts may generate new trophoblast cells which contribute to increased cell number during both diapause and activation stages, and 2) activation of blastocysts after diapause is related to the production of trophoblast cells with enhanced synthetic capabilities. 相似文献
69.
Electrostatic mechanisms underlie neomycin block of the cardiac ryanodine receptor channel (RyR2) 下载免费PDF全文
Neomycin is a large, positively charged, aminoglycoside antibiotic that has previously been shown to induce a voltage-dependent substate block in the cardiac isoform of the ryanodine receptor (RyR2). It was proposed that block involved an electrostatic interaction between neomycin and putative regions of negative charge in both the cytosolic and luminal mouths of the pore. In this study, we have attempted to screen charge by increasing potassium concentration in single-channel experiments. Neomycin block is apparent at both cytosolic and luminal faces of the channel in all K+ concentrations tested and alterations in K+ concentration have no effect on the amplitudes of the neomycin-induced substates. However, the kinetics of both cytosolic and luminal block are sensitive to changes in K+ concentration. In both cases increasing the K+ concentration leads to an increase in dissociation constant (KD). Underlying these changes are marked increases in rates of dissociation (k(off)), with little change in rates of association (k(on)). The increase in k(off) is more marked at the luminal face of the channel. Changes in K+ concentration also result in alterations in the voltage dependence of block. We have interpreted these data as supporting the proposal that neomycin block of RyR2 involves electrostatic interactions with the polycation forming a poorly fitting "plug" in the mouths of the conduction pathway. These observations emphasize the usefulness of neomycin as a probe for regions of charge in both the cytosolic and luminal mouths of the RyR2 pore. 相似文献
70.
Oliver Windram Priyadharshini Madhou Stuart McHattie Claire Hill Richard Hickman Emma Cooke Dafyd J. Jenkins Christopher A. Penfold Laura Baxter Emily Breeze Steven J. Kiddle Johanna Rhodes Susanna Atwell Daniel J. Kliebenstein Youn-sung Kim Oliver Stegle Karsten Borgwardt Cunjin Zhang Alex Tabrett Roxane Legaie Jonathan Moore B?rbel Finkenstadt David L. Wild Andrew Mead David Rand Jim Beynon Sascha Ott Vicky Buchanan-Wollaston Katherine J. Denby 《The Plant cell》2012,24(9):3530-3557