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排序方式: 共有310条查询结果,搜索用时 328 毫秒
1.
Biotin and protein synthesis in rat liver 总被引:5,自引:0,他引:5
2.
A hierarchical breeding design was used to determine if winter flounder Pseudopleuronectes americanus embryos and yolk-sac larvae sired by Georges Bank males developed and grew larger than fish sired by Passamaquoddy Bay males, and to examine parental contributions to variations in fertilization success, time to 50% hatch, hatch success and larval morphological development. Significant stock effects were detected for time to hatch and larval development. Eggs fertilized by Passamaquoddy Bay males reached 50% hatch significantly earlier than eggs fertilized by Georges Bank males. Larvae sired by Georges Bank males were significantly larger during larval development for four of the six traits measured at 12 days post-hatch: head depth, jaw length, myotome height and body area. Embryo and larval development were strongly influenced by maternal contributions; there were significant maternal variance components for the majority of the variables measured. Paternal variance components were significant for fertilization success, time to hatch, larval jaw length and larval head depth, however, they acted principally through parental interactions. This information has important implications for the long-term sustainable development of winter flounder for aquaculture purposes as well as for understanding winter flounder genetic variation in the wild. 相似文献
3.
Human immunodeficiency virus reverse transcriptase expressed in transformed yeast cells. Biochemical properties and interactions with bovine tRNALys 总被引:11,自引:0,他引:11
4.
Further biochemical characterization of wheat DNA primase: possible functional implication of copurification with DNA polymerase A. 总被引:3,自引:0,他引:3 下载免费PDF全文
DNA primase has been partially purified from wheat germ. This enzyme, like DNA primases characterized from many procaryotic and eucaryotic sources, catalyses the synthesis of primers involved in DNA replication. However, the wheat enzyme differs from animal DNA primase in that it is found partially associated with a DNA polymerase which differs greatly from DNA polymerase alpha. Moreover, the only wheat DNA polymerase able to initiate on a natural or synthetic RNA primer is DNA polymerase A. In this report we describe in greater detail the chromatographic behaviour of wheat DNA primase and its copurification with DNA polymerase A. Some biochemical properties of wheat DNA primase such as pH optimum, Mn + 2 or Mg + 2 optima, and temperature optimum have been determined. The enzyme is strongly inhibited by KCI, cordycepine triphosphate and dATP, and to a lesser extent by cAMP and formycine triphosphate. The primase product reaction is resistant to DNAse digestion and sensitive to RNAse digestion. Primase catalyses primer synthesis on M13 ssDNA as template allowing E.coli DNA polymerase I to replicate the primed M13 single-stranded DNA leading to double-stranded M13 DNA (RF). M13 replication experiments were performed with wheat DNA polymerases A, B, CI and CII purified in our laboratory. Only DNA polymerase A is able to recognize RNA-primed M13 ssDNA. 相似文献
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In vitro and in vivo studies of Trypanosoma cruzi DNA polymerase 总被引:1,自引:0,他引:1
A Solari D Tharaud Y Repetto J Aldunate A Morello S Litvak 《Biochemistry international》1983,7(2):147-157
One major DNA polymerase has been purified and characterized from Trypanosoma cruzi. The enzyme has a sedimentation coefficient of 6.8 S corresponding to an approximate molecular weight of 180,000 assuming a globular shape. The enzyme recognizes activated DNA very efficiently, as well as synthetic polydeoxynucleotides, whereas poly rA-dT12 is very poorly utilized. Trypanosoma cruzi DNA polymerase is not inhibited at all by aphidicolin, while araCTP inhibits the enzyme very slightly. The purified enzyme is strongly inhibited by N-ethyl maleimide, dideoxyTTP, ethidium bromide and berenil. All our attempts to find a DNA polymerase sensitive to aphidicolin in vitro have failed, nor have we been able to find a low molecular weight DNA polymerase in this organism. However, when DNA synthesis was studied in whole trypanosomes, aphidicolin was shown to inhibit DNA synthesis more efficiently than ethidium bromide and berenil. 相似文献
8.
The response of isoprene emission rate and photosynthetic rate to photon flux and nitrogen supply in aspen and white oak trees 总被引:4,自引:0,他引:4
M. E. Litvak F. Loreto P. C. Harley T. D. Sharkey R. K. Monson 《Plant, cell & environment》1996,19(5):549-559
Isoprene is the primary biogenic hydrocarbon emitted from temperate deciduous forest ecosystems. The effects of varying photon flux density (PFD) and nitrogen growth regimes on rates of isoprene emission and net photosynthesis in potted aspen and white oak trees are reported. In both aspen and oak trees, whether rates were expressed on a leaf area or dry mass basis, (1) growth at higher PFD resulted in significantly higher rates of isoprene emission, than growth at lower PFD, (2) there is a significant positive relationship between isoprene emission rate and leaf nitrogen concentration in both sun and shade trees, and (3) there is a significant positive correlation between isoprene emission rate and photosynthetic rate in both sun and shade trees. The greater capacity for isoprene emission in sun leaves was due to both higher leaf mass per unit area and differences in the biochemical and/or physiological properties that influence isoprene emission. Positive correlations between isoprene emission rate and leaf nitrogen concentration support the existence of mechanisms that link leaf nitrogen status to isoprene synthase activity. Positive correlations between isoprene emission rate and photosynthesis rate support previous hypotheses that isoprene emission plays a role in protecting photosynthetic mechanisms during stress. 相似文献
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Matthew K. Litvak 《Environmental Biology of Fishes》1993,36(2):183-192
Synopsis Many species of shoaling fish are preyed upon by aerial predators. However, to date there has been no analysis of the evasive
response of a group of shoaling fish to an aerial threat or attack. The response of a shoal of fish encompasses a suite of
behaviors starting with a startle response. Shoals of golden shiner, Notemigonus crysoleucas, responded to the threat of aerial predation from a kingfisher model with a startle response, an increase in shoal depth,
an increase in polarity, swimming in the opposite direction under the model predator, shoal compression along the depth axis,
and shoal expansion on the plane perpendicular to the depth axis. It was hypothesized that shoal compression along the depth
axis serves to increase predator confusion by placing more fish in the predator's visual field. This compression was termed
the ‘plane of confusion’. 相似文献