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排序方式: 共有175条查询结果,搜索用时 25 毫秒
1.
Bhaskaran S. Smith R. H. Paliwal S. Schertz K. F. 《Plant Cell, Tissue and Organ Culture》1987,9(3):189-196
Plant Cell, Tissue and Organ Culture (PCTOC) - Sorghum bicolor (L.) Moench, plants were regenerated from 4 to 5 month old callus cultures originally derived from seedling explants. Somaclonal... 相似文献
2.
High level of divergence of male-reproductive-tract proteins, between Drosophila melanogaster and its sibling species, D. simulans 总被引:1,自引:0,他引:1
We compared male-reproductive-tract polypeptides of Drosophila melanogaster
and D. simulans by using two-dimensional gel electrophoresis. Approximately
64% of male-reproductive-tract polypeptides were identical between two
randomly chosen isofemale lines from these two species, compared with 83%
identity for third-instar imaginal wing-disc polypeptides. Qualitatively
similar differences were found between reproductive tracts and imaginal
discs when D. sechellia was compared with D. melanogaster and with D.
simulans. When genic polymorphism was taken into account, approximately 10%
of male- reproductive-tract polypeptides were apparently fixed for
different alleles between D. melanogaster and D. simulans; this proportion
is the same as that found for soluble enzymes by one-dimensional gel
electrophoresis. Strikingly, approximately 20% of male-reproductive- tract
polypeptides of either D. melanogaster or D. simulans had no detectable
homologue in the other species. We propose that proteins of the Drosophila
male reproductive tract may have diverged more extensively between species
than have other types of proteins and that much of this divergence may
involve large changes in levels of polypeptide expression.
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3.
4.
Ribulose Bisphosphate Carboxylase Activity in Anther-Derived Plants of Saintpaulia ionantha Wendl. Shag
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Plants obtained from anther culture of the African violet, Saintpaulia ionantha Wendl. `Shag' and vegetatively cloned copies of the parent anther donor plant were examined for their ploidy and ribulose-1,5-biphosphate carboxylase (RuBPcase) activity. The cloned parent plants were all diploid and did not vary much in their nuclear DNA, chlorophyll, and RuBPcase activity. Some of the anther-derived plants were similar to the parent plants while others were not. Different levels of ploidy were observed among the androgenetic plants. RuBPcase activities higher than that of the parent plants were found in some anther-derived plants. However, there was no direct correlation between ploidy and RuBPcase activity. Expression of nuclear genes from a single parent in the anther-derived plants and it's diploidization or plastid changes during early stages of microsporogenesis or androgenesis are suggested as possible reasons for the variations observed among them. This could be a useful technique to obtain physiological variants which could be agronomically desirable. 相似文献
5.
Sex pili in Vibrio cholerae 总被引:1,自引:0,他引:1
6.
Balagopalan Unni Punnee Barrera Malgorzata Muszynska-Pytel Govindan Bhaskaran Karl H. Dahm 《Archives of insect biochemistry and physiology》1993,24(4):173-185
During the last larval stage, corpora allata (CA) of Manduca sexta are inactivated by a factor from the brain. Apparently the same factor (allatinhibin, Al) is secreted by day 4 Vth instar brains kept overnight in Grace's medium. Al is rapidly inactivated by heat or acid but withstands exposure to alkali and can be recovered after freezing and lyophilization. Exposure to pronase, chymotrypsin, carboxypeptidases-A and-Y, as well as leucine aminopeptidase eliminated Al activity completely, whereas after exposure to trypsin and protease XVII-S, some residual activity remained. Inactivation by pyroglutamate aminopeptidase is interprefed as being due to prolinase activity of this enzyme. Incubation of CA with gentamicin, an aminoglycoside antibiotic, affects neither their ability to produce JH in vitro nor their viability in implantation assays. However, Al did not inactivate CA in the presence of low concentrations of gentamicin. This effect was used to guard against false positive assay results possibly produced by allatotoxic contamination. Al was purified by chromatography on Sephadex G-25. All activity recovered emerged from the columns in intermediate fractions with an apparent Mr of 1,000–2,000. © 1993 Wiley-Liss, Inc. 相似文献
7.
RS Fisher 《The Journal of general physiology》1977,69(5):571-604
When the outer surface of short-circuited frog skin was penetrated with microelectrodes, stable negative potentials that averaged near -100 mV were recorded consistently, confirming the results of Nagel (W. Nagel. 1975. Abstracts of the 5th International Biophysics Congress, Copenhagen. P-147.). The appearance of these stable potentials, V(O), concurrent with the observations that (a) a high resistance outer barrier R(O) accounting for approximately 75 percent or more of the transcellular resistance of control skins had been penetrated and that (b) 10(-5) M amiloride and reduced [Na] outside caused the values of V(O) to increase towards means value near -130 mV while the values of percent R(O) increased to more than 90 percent. It was of relationships were the same as the values of E(1) observed in studies of the current-voltage relationships were the same as the values of E’(1) defined as the values of voltage at the inner barrier when the V(O) of the outer barrier was reduced to zero by voltage clamping of the skins. Accordingly, these data are interpreted to mean that the values of E(1), approximately 130 mV, represent the E(Na) of the sodium pump at the inner barrier. 2,4-DNP was observed to decrease the values of transepithelial voltage less than E(1) the V(O) was negative. These data can be interpreted with a simple electrical equivalent circuit of the active sodium transport pathway of the frog skin that includes the idea that the outer membrane behaves as an electrical rectifier for ion transport. 相似文献
8.
9.
The conformation of oxytocin, the neurohypophyseal nonapeptide hormone, in solution in deuterated dimethyl sulfoxide has been determined by 1H-nmr. The structural determination is based on the experimental data set of nuclear Overhauser effect restraints. Obtained after the restrained molecular dynamics simulation on an initial structure of extended conformation, five resultant structures satisfy the experimental restraints well. These structures resemble that of the crystal structure of deamino-oxytocin, an analogue of oxytocin, in terms of a close correlation observed both at two beta-turn regions of the 20-membered tocin ring and at the tripeptide tail end. Based on this comparison and analysis of restrained molecular dynamics trajectories, we found that, although the turns are stabilized by the formation of hydrogen bonds, the oxytocin molecule possesses a slight twist in DMSO solution relative to the orientation of deamino-oxytocin in the crystalline state. Analyses of oxytocin conformation indicate that the tripeptide tail is more flexible than the tocin ring. 相似文献
10.
Summary Larvae of the danid butterfly Danaus chrysippus, fed on the milkweeds Calotropis gigantea and Asclepias curassavica grew successfully during the 9-day feeding period and pupated. In the presence of these milkweeds, the larvae preferred to feed on C. gigantea. Their preference was more pronounced during the final 2 instars than during the initial 3 instars. They consumed 605 mg, defecated 308 mg, and converted 115 mg of C. gigantea; those receiving A. curassavica consumed 563 mg, defecated 287 mg and converted 85 mg. They assimilated either food with equal efficiency (: 46%; : 50%). But they differed significantly in their efficiency in converting the assimilated food. The presence of a greater amount of latex in C. gigantea than in A. curassavica and/or the nutritional inadequacy of the latter food may perhaps be the reason(s) for the preference of C. gigantea by D. chrysippus larvae over A. curassavica. 相似文献