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91.
Sea urchin Hox genes: insights into the ancestral Hox cluster 总被引:3,自引:0,他引:3
We describe the Hox cluster in the radially symmetric sea urchin and
compare our findings to what is known from clusters in bilaterally
symmetric animals. Several Hox genes from the direct-developing sea urchin
Heliocidaris erythrogramma are described. CHEF gel analysis shows that the
Hox genes are clustered on a < or = 300 kilobase (kb) fragment of DNA,
and only a single cluster is present, as in lower chordates and other
nonvertebrate metazoans. Phylogenetic analyses of sea urchin, amphioxus,
Drosophila, and selected vertebrate Hox genes confirm that the H.
erythrogramma genes, and others previously cloned from other sea urchins,
belong to anterior, central, and posterior groups. Despite their radial
body plan and lack of cephalization, echinoderms retain at least one of the
anterior group Hox genes, an orthologue of Hox3. The structure of the
echinoderm Hox cluster suggests that the ancestral deuterostome had a Hox
cluster more similar to the current chordate cluster than was expected Sea
urchins have at least three Abd-B type genes, suggesting that Abd-B
expansion began before the radiation of deuterostomes.
相似文献
92.
93.
Claire M. Fraser Roger Greguski Barbara Eddy J. Craig Venter 《Journal of cellular biochemistry》1983,21(3):219-231
The combination of immunological advances with membrane receptor research has promoted rapid progress in the molecular characterization of neurotransmitter receptor molecules. We have to date produced monoclonal antibodies to β1-, β2-, and β1-adrenergic, D2-dopaminergic, and muscarinic receptors. In addition we have discovered that some allergic respiratory disease patients possess circulating autoantibodies to β2-adrenergic receptors. These antireceptor antibodies in conjunction with specific receptor affinity reagents have allowed us to isolate, purify, and begin to characterize α- and β-adrenergic, dopaminergic, and muscarinic receptors. For example, immunoprecipitation of turkey erythrocyte β1 receptors with monoclonal antibodies yields a single polypeptide Mr 65–70 K. In contrast, purification of β2-adrenergic receptors using either autoantibodies or monoclonal antibodies yields a receptor species with a subunit of Mr 55–59 K. Autoantibodies to β2 receptors demonstrate a 50–100% homology among β2 receptors from humans to rats, whereas monoclonal antibody FV-104 recognizes a determinant in the ligand binding site of all β1 and β2 receptors tested to date. These data suggest that β1- and β2-adrenergic receptors may have evolved from a common ancestor, perhaps by gene duplication. 相似文献
94.
95.
96.
Robin Resch Charlton J.Craig Venter 《Biochemical and biophysical research communications》1980,94(4):1221-1226
The concentration of β-adrenergic receptors in synchronized C6 cells is lowest during mitosis and G1 (1000–2000 receptors/cell). A rapid increase in β-receptor concentration occurs in early S phase to 9000 receptors/cell, followed by a decrease during G2 to the low concentration found at mitosis. In non-synchronized C6 cell populations, mitotic cells have one-half of the average β-receptor concentration of the population as a whole, confirming the observations made with synchronized cells. 相似文献
97.
Summary Different iron compounds were compared for use in nutrient solutions for nodulation studies withTrifolium pratense L. (Montgomery Red). Iron(III)-EDTA was found to be the best source of iron when taking both nodulation and yield into account. The possibility of toxic effects under certain experimental conditions can, however, not be excluded. 相似文献
98.
Localization of the gene encoding the GABAA receptor β3 subunit to the Angelman/Prader-Willi region of human chromosome 15 下载免费PDF全文
J. Wagstaff J. H. M. Knoll J. Fleming E. F. Kirkness A. Martin-Gallardo F. Greenberg J. M. Graham J. Menninger D. Ward J. C. Venter M. Lalande 《American journal of human genetics》1991,49(2):330-337
Deletions of the proximal long arm of chromosome 15 (bands 15q11q13) are found in the majority of patients with two distinct genetic disorders, Angelman syndrome (AS) and Prader-Willi syndrome (PWS). The deleted regions in the two syndromes, defined cytogenetically and by using cloned DNA probes, are similar. However, deletions in AS occur on the maternally inherited chromosome 15, and deletions in PWS occur on the paternally derived chromosome 15. This observation has led to the suggestion that one or more genes in this region show differential expression dependent on parental origin (genetic imprinting). No genes of known function have previously been mapped to this region. We show here that the gene encoding the GABAA (gamma-aminobutyric acid) receptor beta 3 subunit maps to the AS/PWS region. Deletion of this gene (GABRB3) was found in AS and PWS patients with interstitial cytogenetic deletions. Evidence of beta 3 gene deletion was also found in an AS patient with an unbalanced 13;15 translocation but not in a PWS patient with an unbalanced 9;15 translocation. The localization of this receptor gene to the AS/PWS region suggests a possible role of the inhibitory neurotransmitter GABA in the pathogenesis of one or both of these syndromes. 相似文献
99.
Pseudomonas aeruginosa diaminopimelate decarboxylase: evolutionary relationship with other amino acid decarboxylases 总被引:1,自引:0,他引:1
Martin C; Cami B; Yeh P; Stragier P; Parsot C; Patte JC 《Molecular biology and evolution》1988,5(5):549-559
The lysA gene encodes meso-diaminopimelate (DAP) decarboxylase
(E.C.4.1.1.20), the last enzyme of the lysine biosynthetic pathway in
bacteria. We have determined the nucleotide sequence of the lysA gene from
Pseudomonas aeruginosa. Comparison of the deduced amino acid sequence of
the lysA gene product revealed extensive similarity with the sequences of
the functionally equivalent enzymes from Escherichia coli and
Corynebacterium glutamicum. Even though both P. aeruginosa and E. coli are
Gram-negative bacteria, sequence comparisons indicate a greater similarity
between enzymes of P. aeruginosa and the Gram- positive bacterium C.
glutamicum than between those of P. aeruginosa and E. coli enzymes.
Comparison of DAP decarboxylase with protein sequences present in data
bases revealed that bacterial DAP decarboxylases are homologous to mouse
(Mus musculus) ornithine decarboxylase (E.C.4.1.1.17), the key enzyme in
polyamine biosynthesis in mammals. On the other hand, no similarity was
detected between DAP decarboxylases and other bacterial amino acid
decarboxylases.
相似文献
100.
[3H]Pirenzepine [( 3H]PZ) and [3H] (-)Quinuclidinylbenzilate [( 3H] (-)QNB) specific binding to soluble rat brain muscarinic cholinergic receptors was assessed as a function of time subsequent to receptor solubilization. The soluble brain muscarinic receptor is stable at 4 degrees C when assayed by [3H] (-)QNB binding (t 1/2 = 80 hrs). In contrast the pirenzepine state of the receptor decays rapidly (t 1/2 = 3.0 hrs). Prior occupation of the receptor with [3H] (-)QNB or [3H]PZ increases the receptor stability by two to five fold (t 1/2 QNB greater than 1,000 hrs; t 1/2 PZ = 6.5 hrs). These data indicate that pirenzepine binds to an allosteric state of the muscarinic receptor and that caution should be employed in the assignment of receptor subtypes based solely upon the binding of ligands which recognize unique conformational states. 相似文献