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R McCarter J McGee S Witherspoon C J Gauntt A Vardiman 《Proceedings of the Society for Experimental Biology and Medicine. Society for Experimental Biology and Medicine (New York, N.Y.)》1986,182(3):308-314
Isometric contractile properties of isolated phrenic nerve-diaphragm muscle preparations were used to study the effects of picornavirus infections on diaphragm muscle function. Properties of muscles from virus-inoculated and control mice were similar during brief contractions. However, when subjected to a series of fatiguing contractions by indirect or direct stimulation, muscles of mice inoculated with a paralytic variant of encephalomyocarditis (EMC) virus showed a greater rate of fatigue and a reduced capacity to recover from fatigue than did muscles from uninoculated control mice or muscles from mice inoculated with a nonparalytic coxsackievirus B3 (CVB3). Mice paralyzed by EMC virus infection had high titers of virus in the brain and similar titers of virus in diaphragm muscle as found in diaphragm muscles of CVB3-inoculated mice. The results indicate that EMC virus infection of mice leads to increased fatigability of the diaphragm muscle and that there are both neural and muscular components of this enhanced fatigue. 相似文献
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Maternal diabetes and cardiovascular malformations: predominance of double outlet right ventricle and truncus arteriosus 总被引:4,自引:0,他引:4
Most studies on the relationship of maternal diabetes to cardiovascular malformations (CVM) have been prospective investigations of pregnancy outcome and therefore could not identify associations with rare cardiac lesions. The results of a retrospective study shed new light on the risks of specific cardiac defects in diabetic pregnancies. The Baltimore-Washington Infant Study, a population-based case-control investigation of CVM, provides information on maternal diabetes reported in personal interviews. Among 2259 mothers of cases, 35 (1.5%) reported diabetes present before pregnancy (called "overt") and 95 (4.2%) reported diabetes only during pregnancy (called "gestational"). Among 2,801 mothers of controls, 14 (0.5%) had overt diabetes and 83 (3.0%) had gestational diabetes. Malformation-specific risks were expressed as odds ratios (OR) with 99.5% confidence intervals (CI). The strongest associations with overt maternal diabetes were found with double outlet right ventricle (OR 21.33; 99.5% CI 3.34, 136.26), and truncus arteriosus (OR 12.81; 99.5% CI 1.43, 114.64). No significant diagnosis-specific associations were found with gestational diabetes. Non-cardiac malformations were present in 23% of infants with CVM whose mothers had overt diabetes and in 26% of infants with CVM whose mother had gestational diabetes, in 32% of infants with CVM whose mothers did not have diabetes, and in 4% of controls. Double outlet right ventricle and truncus arteriosus are malformations dependent upon neural-crest-cell-derived ectomesenchymal tissues; these are precisely the conotruncal abnormalities that result from experimental ablation of the neural crest in chick embryos. The association with diabetes suggests a further etiologic link between these two lesions. 相似文献
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Litman GW; Rast JP; Shamblott MJ; Haire RN; Hulst M; Roess W; Litman RT; Hinds- Frey KR; Zilch A; Amemiya CT 《Molecular biology and evolution》1993,10(1):60-72
Immunoglobulins are encoded by a large multigene system that undergoes
somatic rearrangement and additional genetic change during the development
of immunoglobulin-producing cells. Inducible antibody and antibody-like
responses are found in all vertebrates. However, immunoglobulin possessing
disulfide-bonded heavy and light chains and domain-type organization has
been described only in representatives of the jawed vertebrates. High
degrees of nucleotide and predicted amino acid sequence identity are
evident when the segmental elements that constitute the immunoglobulin gene
loci in phylogenetically divergent vertebrates are compared. However, the
organization of gene loci and the manner in which the independent elements
recombine (and diversify) vary markedly among different taxa. One striking
pattern of gene organization is the "cluster type" that appears to be
restricted to the chondrichthyes (cartilaginous fishes) and limits
segmental rearrangement to closely linked elements. This type of gene
organization is associated with both heavy- and light-chain gene loci. In
some cases, the clusters are "joined" or "partially joined" in the germ
line, in effect predetermining or partially predetermining, respectively,
the encoded specificities (the assumption being that these are expressed)
of the individual loci. By relating the sequences of transcribed gene
products to their respective germ-line genes, it is evident that, in some
cases, joined-type genes are expressed. This raises a question about the
existence and/or nature of allelic exclusion in these species. The
extensive variation in gene organization found throughout the vertebrate
species may relate directly to the role of intersegmental
(V<==>D<==>J) distances in the commitment of the individual
antibody-producing cell to a particular genetic specificity. Thus, the
evolution of this locus, perhaps more so than that of others, may reflect
the interrelationships between genetic organization and function.
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Rainbow trout developed elevated hepatic metallothionein concentrations after 4 weeks in a solution containing zinc, copper and cadmium in a fixed ratio of 400:20:1. Resistance to a combination of these metals increased in proportion to the concentration to which they were exposed for 4 weeks. The concentration of copper but not zinc or cadmium in the low molecular weight proteins separated by gel filtration was related to the concentrations of metallothionein present. The combined toxicity of the metals in the mixture was additive. 相似文献
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