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1.
In view of the evidence that lymphocyte infiltrates are a constant feature of the skin lesions of psoriasis and the demonstration that certain hydroxylated metabolites of arachidonic acid are present in lesional psoriatic skin and possess lymphocyte chemoattractant properties, lipid extracts of samples from lesional and normal skin were assayed to determine which are the predominant lipid lymphocyte chemoattractants in psoriasis. Dilution-related lymphocyte chemoattractant activity was found in lipid extracts of stratum corneum samples from psoriatic lesions, but not in similar extracts the samples from both sources contained equivalent amounts of this activity. Subsequent purification of lesional stratum corneum lipid extracts by straight and reversed phase high performance liquid chromatography (HPLC) revealed the presence of at least two different lipid chemoattractants, one major component being identified as 12-(R)-hydroxy-5,8,10,14-eicosatetraenoic acid (12[R]-HETE) by its biological and chromatographic properties. These compounds may play a role in the pathogenesis of the lymphocyte infiltrates in psoriatic lesions. 相似文献
2.
Cell wall residues in yeast protoplast preparations 总被引:5,自引:2,他引:3
Protoplast preparations made from Saccharomyces cerevisiae by prolonged treatment with snail digestive juice contained fibrils and chitinous bud-scar residues from the original cell wall. 相似文献
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alpha-Oligodeoxynucleotide stability in serum, subcellular extracts and culture media 总被引:1,自引:0,他引:1
T A Bacon F Morvan B Rayner J L Imbach E Wickstrom 《Journal of biochemical and biophysical methods》1988,16(4):311-318
Degradation of a synthetic alpha-oligodeoxynucleotide was studied in order to compare its survival with naturally occurring beta-oligodeoxynucleotides in five systems used for antisense hybridization arrest experiments. In contrast to beta-oligodeoxynucleotides, alpha-oligodeoxynucleotides were not detectably degraded over 24 h at 37 degrees C in HeLa cell postmitochondrial cytoplasmic extract or RPMI 1640 with 10% fetal bovine serum, and showed significant survival after 24 h at 37 degrees C in rabbit reticulocyte lysate, fetal bovine serum and human serum. 相似文献
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The biochemical control of leaf expansion during drought 总被引:6,自引:0,他引:6
Mark A. Bacon 《Plant Growth Regulation》1999,29(1-2):101-112
Over the past decade it has become clear that we cannot always explain the observed reduction in leaf expansion rates during drought by measuring the plant's water relations. This has led us to question the possibility of a role for the cell wall and its biochemical machinery in controlling the rate of leaf expansion during drought. However, if we are to reject or modify previous assumptions regarding the control of leaf expansion during drought, then we must offer alternative explanations. This article addresses recent work from this laboratory and in the literature, concerning the involvement of cell wall-enzymes, pH and abscisic acid (ABA) in regulating leaf expansion during water deficit. 相似文献
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The Triassic–Jurassic boundary (Tr–J; ∼201 Ma) is marked by a doubling in the concentration of atmospheric CO2, rising temperatures, and ecosystem instability. This appears to have been driven by a major perturbation in the global carbon cycle due to massive volcanism in the Central Atlantic Magmatic Province. It is hypothesized that this volcanism also likely delivered sulphur dioxide (SO2) to the atmosphere. The role that SO2 may have played in leading to ecosystem instability at the time has not received much attention. To date, little direct evidence has been presented from the fossil record capable of implicating SO2 as a cause of plant extinctions at this time. In order to address this, we performed a physiognomic leaf analysis on well-preserved fossil leaves, including Ginkgoales, bennettites, and conifers from nine plant beds that span the Tr–J boundary at Astartekløft, East Greenland. The physiognomic responses of fossil taxa were compared to the leaf size and shape variations observed in nearest living equivalent taxa exposed to simulated palaeoatmospheric treatments in controlled environment chambers. The modern taxa showed a statistically significant increase in leaf roundness when fumigated with SO2. A similar increase in leaf roundness was also observed in the Tr–J fossil taxa immediately prior to a sudden decrease in their relative abundances at Astartekløft. This research reveals that increases in atmospheric SO2 can likely be traced in the fossil record by analyzing physiognomic changes in fossil leaves. A pattern of relative abundance decline following increased leaf roundness for all six fossil taxa investigated supports the hypothesis that SO2 had a significant role in Tr–J plant extinctions. This finding highlights that the role of SO2 in plant biodiversity declines across other major geological boundaries coinciding with global scale volcanism should be further explored using leaf physiognomy. 相似文献
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