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排序方式: 共有525条查询结果,搜索用时 750 毫秒
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gltF, a member of the gltBDF operon of Escherichia coli, is involved in nitrogen-regulated gene expression 总被引:4,自引:0,他引:4
Irene Castaño † Noemi Flores Fernando Valle Alejandra A. Covarrubias Francisco Bolivar 《Molecular microbiology》1992,6(18):2733-2741
We report here the construction and analysis of insertional mutations in each of the three genes of the gltBDF operon and the nucleotide sequence of the region downstream from gltD. Two open reading frames were identified, the first of which corresponds to gltF. The gltB and gltD genes code for the large and small subunits, respectively, of the enzyme glutamate synthase (GOGAT). gltF codes for a protein, with a molecular mass of 26,350 Da, which is required for Ntr induction. Histidase synthesis was determined as a measure of Ntr function. First, insertions in gltB, gltD or gltF all prevent Ntr induction. Second, complementation analysis indicates that high-level expression of both the gltD and gltF genes is required for the induction of the Ntr enzymes under nitrogen-limiting conditions, indicating that the phenotype of the gltB insertion probably results from polarity on gltD and gltF. Third, glutamate-dependent repression of the glt operon appears to be mediated by the product of the gltF gene. Thus, the gltBDF operon of Escherichia coli is involved in induction of the so-called Ntr enzymes in response to nitrogen deprivation, as well as in glutamate biosynthesis. 相似文献
3.
Calcitonin and CGRP block bombesin- and substance P-induced increases in airway tone 总被引:3,自引:0,他引:3
Gatto C.; Lussky R. C.; Erickson L. W.; Berg K. J.; Wobken J. D.; Johnson D. E. 《Journal of applied physiology》1989,66(2):573-577
Calcitonin gene-related peptide (CGRP) and calcitonin (C) are two peptides that are cocontained and probably coreleased with the potent bronchocontrictors, bombesin (B) and substance P (SP), within the lung. Although CGRP and C have a wide intrapulmonary distribution, their actions have not been well defined. By the use of a computerized lung mechanics analyzer, changes in response to 10-min infusions of these agents were measured in spontaneously breathing, anesthetized guinea pigs. Infusion of 0.3 nmol.kg-1.min-1 CGRP and 2 nmol.kg-1.min-1 C caused little change in lung mechanics. Infusion of 0.06 nmol.kg-1.min-1 B and 0.3 nmol.kg-1.min-1 SP caused a marked increase in inspiratory, expiratory, and total pulmonary resistance (RT), from base-line values (P less than 0.02), with a maximal effect at 10 min postinfusion (PI) [RT = 326 +/- 20% (SE) (B), 490 +/- 73% (SP)]. Coinfusion of C or CGRP with B or SP at the above concentrations caused a marked reduction in SP - [RT = 189 +/- 28% (C), 142 +/- 16% (CGRP) at 10 min PI] and B - [RT = 157 +/- 18% (C), 158 +/- 10% (CGRP) at 10 min PI] induced changes in resistance (P less than 0.015). The mode of action of C and CGRP is unknown, but these peptides may antagonize the effects of B and SP via autonomic pathways by interfering with B- or SP-induced changes in intracellular calcium concentrations or by increasing intracellular cAMP levels by binding to specific cellular receptors linked to adenylate cyclase. 相似文献
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Exon and intron sequences, respectively, repress and activate splicing of a fibroblast growth factor receptor 2 alternative exon. 总被引:26,自引:12,他引:14
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Two alternative exons, BEK and K-SAM, code for part of the ligand binding site of fibroblast growth factor receptor 2. Splicing of these exons is mutually exclusive, and the choice between them is made in a tissue-specific manner. We identify here pre-mRNA sequences involved in controlling splicing of the K-SAM exon. The short K-SAM exon sequence 5'-TAGGGCAGGC-3' inhibits splicing of the exon. This inhibition can be overcome by mutating either the exon's 5' or 3' splice site to make it correspond more closely to the relevant consensus sequence. Two separate sequence elements in the intron immediately downstream of the K-SAM exon, one of which is a sequence rich in pyrimidines, are both needed for efficient K-SAM exon splicing. This is no longer the case if either the exon's 5' or 3' splice site is reinforced. Furthermore, if the exon inhibitory sequence is removed, the intron sequences are not required for splicing of the K-SAM exon in a cell line which normally splices this exon. At least three elements are thus involved in controlling splicing of the K-SAM exon: suboptimal 5' and 3' splice sites, an exon inhibitory sequence, and intron activating sequences. 相似文献
6.
Noemi Luknar-Gabor Ursula Fenger Christoph Wagener Heinz Breuer 《Biochemical and biophysical research communications》1982,109(4):1270-1275
A variant of the carcinoembryonic antigen (CEA) with lower molecular weight than a CEA reference preparation has been separated from CEA. Using a polyclonal, spleen absorbed anti-CEA antiserum, the variant crossreacts with reference CEA in immunodiffusion. The CEA-activity of the variant has been demonstrated using an enzyme-immunoassay with monoclonal CEA specific antibodies. There is sufficient immunological evidence that this variant is a distinct antigen different from the crossreactive antigens described so far. The reactivity of the polyclonal anti-CEA antiserum with the CEA variant was abolished by absorption against the immobilized variant. 相似文献
7.
Green hydra with endosymbionts are smaller than brown asymbiotic ones. Regeneration experiments, mitotic index studies on algal and hydra tissue, and evidence for consumption and expulsion of algae are reviewed and it is suggested that larger green hydra have more difficulty controlling algal increase than smaller ones and that hydra have an upper size limit for maintenance of stable symbioses. A mathematical model is discussed which starts with simple physiological assumptions about hydra and generates field testable conclusions about how body and bud size, and reproductive rates depend on food particle size, quantity and temporal distribution. Unlike most analytic ecological-evolutionary models, this one integrates physiology, ecology and evolution without needing simplifying assumptions. 相似文献
8.
Birgit H M Meldal Carles Pons Livia Perfetto Noemi Del-Toro Edith Wong Patrick Aloy Henning Hermjakob Sandra Orchard Pablo Porras 《Nucleic acids research》2021,49(6):3156
The EMBL-EBI Complex Portal is a knowledgebase of macromolecular complexes providing persistent stable identifiers. Entries are linked to literature evidence and provide details of complex membership, function, structure and complex-specific Gene Ontology annotations. Data are freely available and downloadable in HUPO-PSI community standards and missing entries can be requested for curation. In collaboration with Saccharomyces Genome Database and UniProt, the yeast complexome, a compendium of all known heteromeric assemblies from the model organism Saccharomyces cerevisiae, was curated. This expansion of knowledge and scope has led to a 50% increase in curated complexes compared to the previously published dataset, CYC2008. The yeast complexome is used as a reference resource for the analysis of complexes from large-scale experiments. Our analysis showed that genes coding for proteins in complexes tend to have more genetic interactions, are co-expressed with more genes, are more multifunctional, localize more often in the nucleus, and are more often involved in nucleic acid-related metabolic processes and processes where large machineries are the predominant functional drivers. A comparison to genetic interactions showed that about 40% of expanded co-complex pairs also have genetic interactions, suggesting strong functional links between complex members. 相似文献
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Katrin Stadelmann Tsogyal D. Latshang Christian M. Lo Cascio Noemi Tesler Anne-Christin Stoewhas Malcolm Kohler Konrad E. Bloch Reto Huber Peter Achermann 《PloS one》2013,8(10)