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91.
Harold L. McMullen John R. Sauer Robert L. Burton 《Journal of insect physiology》1976,22(9):1281-1285
The mouth is confirmed as the site of water vapor uptake in the lone star tick, Amblyomma americanum. It was shown that the level of chloride (36Cl) increased in the mouthparts of desiccated ticks. The highest levels of 36Cl were found in the mouthparts, salivary glands, and gut tissue during rehydration. It is suggested that ions are secreted by the salivary glands into the mouth where water is picked up hygroscopically by the secretion. It is further suggested that the water and ions are then swallowed and absorbed from the lumen of the gut. 相似文献
92.
Eimeria stiedai or Eimeria tenella oocysts were incubated in aqueous cysteine hydrochloride (cysHCl) under carbon dioxide (CO2), aqueous cysHCl under air, water under CO2 or water under air, and analyzed for sulfhydryl (-SH) groups. The cysHCl-CO2 treatment produced more -SH groups than the other treatments and was effective in allowing activation of intact and sodium hypochlorite (NaOCl)-treated E. stiedai oocysts as well as NaOCl-treated E. tenella oocysts. The CO2-cysHCl complex may act directly on the oocyst wall, especially in the micropylar region, to unmask lipid-shielded disulfide bridges, which are reduced to -SH groups. The reduction apparently disturbs the protein superstructure of the oocyst wall, promotes opening of the micropyle, and changes the impermeable state of the sporulated oocyst. 相似文献
93.
Burton J. Litman 《生物化学与生物物理学报:生物膜》1975,413(2):157-162
A method has been developed for the selective determination of the fatty acid side chain distribution associated with the amino containing phospholipids located in the inner and outer surfaces of membranes. Using sonicated phosphatidylethanolamine/phosphatidylcholine vesicles as a model, the analysis consists of selective labeling of the outer surface amino groups with the membrane impermeable reagent 2,4,6-trinitrobenzenesulfonic acid. Outer and inner surface phosphatidylethanolamine fractions are separated by thin-layer chromatography. Analysis of methyl esters derived from these two fractions, by gas-liquid chromatography, yields the fatty acid side chain distribution. Our results show that there is no mol fraction dependence of the incorporation of any specific fatty acid side chains of egg yolk phosphatidylethanolamine into the vesicle or any preferential distribution of these side chains in the inner or outer vesicle surface. The surface distribution of the egg yolk phosphatidylethanolamine molecules in these vesicles appears to be determined by the head group packing requirements and not the fatty acid side chain composition. 相似文献
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The inhibition of autoxidation of plasma lipids by vitamin C (ascorbic acid) has been studied. The ascorbate stoichiometric factor, n, i.e., the number of peroxyl radicals trapped by each ascorbate molecule, decreases as the concentration of ascorbate increases. This is attributed to the fact that ascorbate not only acts as a radical-trapping antioxidant, but can also undergo autoxidation. The data indicate that n----2.0 as [ascorbate]----0 and that n----0 as [ascorbate]----infinity. This concentration-dependent behaviour accounts for the wide variation of n values reported in the literature. It is suggested that this autoxidative destruction of ascorbate may play a role regulating its concentration in blood plasma. 相似文献
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A molecular phylogeny of New World emballonurid bats based on parsimony and Bayesian analyses of loci from the three different
nuclear genetic transmission pathways in mammals (autosomal, X, and Y chromosomes) is well supported and independently corroborated by each individual gene tree. This is in contrast to a single
most parsimonious but poorly supported tree based on morphological data, which has only one intergeneric or higher relationship
shared with the molecular phylogeny. Combining the morphological and molecular data partitions results in a tree similar to
the molecular tree suggesting a high degree of homoplasy and low phylogenetic signal in the morphological data set. Behavioral
data are largely incomplete and likewise produce a poorly resolved tree. Nonetheless, patterns of evolution in morphology
and behavior can be investigated by using the molecular tree as a phylogenetic framework. Character optimization of the appearance
of dorsal fur and preferred roosting sites maps consistently and are correlated on the phylogeny. This suggests an association
of camouflage for bats with unusual appearance (two dorsal stripes in Rhynchonycteris and Saccopteryx, or pale fur in Cyttarops and Diclidurus) and roosting in exposed sites (tree trunks or under palm leaves). In contrast, the ancestral states for Old and New World
emballonurids are typically uniform brown or black, and they usually roost in sheltered roosts such as caves and tree hollows.
Emballonuridae is the only family of bats that has a sac-like structure in the wing propatagium, which is found in four New
World genera. Mapping the wing sac character states onto the phylogeny indicates that wing sacs evolved independently within
each genus and that there may be a phylogenetic predisposition for this structure. Ear orientation maps relatively consistently
on the molecular phylogeny and is correlated to echolocation call parameters and foraging behavior, suggesting a phylogenetic
basis for these character systems. 相似文献
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J. E. Burton 《BMJ (Clinical research ed.)》1882,1(1111):556-557