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1.
Escherichia coli ribosomal protein L2 interacts with fMet-tRNAMet and NacPhe-tRNAPhe in solution, protecting their 3'-ends from enzymatic degradation. At the same time L2 enhances the rate of spontaneous hydrolysis of the ester bonds between terminal riboses and amino acyl moieties of these two peptidyl-tRNA analogues. L2 has, however, only a slight effect on the rate of spontaneous deacylation of aminoacyltRNAs. We suggest that the role of L2 is in the fixation of the aminoacyl stem of tRNA to the ribosome at its P-site, and speculate that this protein is directly involved in the peptidyl transferase (PT) reaction. Peptidyl transferase Protein L2 tRNA-protein complex 相似文献
2.
Thymopentin antagonizes stress-induced changes of GABA/benzodiazepine receptor complex 总被引:2,自引:0,他引:2
V Klusa R A Kiivet R Muceniece I Liepa J Harro S Svirskis A Andermanis L R?go 《Regulatory peptides》1990,27(3):355-365
Intraperitoneal administration of thymopentin, a thymopentin II-derived pentapeptide, had no stable and evident effect in the two anxiety models (elevated plus-maze and licking-conflict test) studied. However, in the elevated plus-maze test thymopentin antagonized the behavioral effects of DMCM, a beta-carboline derivative with anxiogenic properties. Further, it was demonstrated that the licking-conflict test procedure itself produced a significant elevation of plasma corticosterone levels, increased the number of [3H]flunitrazepam and decreased the number of [3H]muscimol binding sites in rat hippocampus. The forced-swimming stress similarly to the licking-conflict test also caused an increase in hippocampal [3H]flunitrazepam binding sites. Although ineffective behaviorally in the tests for anxiety, thymopentin pretreatment effectively reversed the changes in corticosterone levels caused by the licking-conflict test. Moreover, it normalized the changed number of benzodiazepine and GABA receptors after stressful stimuli. It is well known that not all anxiolytic drugs (i.e. buspirone) are equally active in behavioral tests for anxiety. According to our data we propose that thymopentin has stress-protective activity. As in vivo and in vitro thymopentin did not change [3H]-flunitrazepam and [3H]muscimol binding, the direct effect of this peptide on the GABA-benzodiazepine-Cl- ionophore receptor complex is unlikely. The action of this peptide on GABA release and/or metabolism can be suggested. 相似文献
3.
Giovanni Melandri Eliana Monteverde David Riewe Hamada AbdElgawad Susan R McCouch Harro Bouwmeester 《Plant physiology》2022,189(2):1139
The possibility of introducing metabolic/biochemical phenotyping to complement genomics-based predictions in breeding pipelines has been considered for years. Here we examine to what extent and under what environmental conditions metabolic/biochemical traits can effectively contribute to understanding and predicting plant performance. In this study, multivariable statistical models based on flag leaf central metabolism and oxidative stress status were used to predict grain yield (GY) performance for 271 indica rice (Oryza sativa) accessions grown in the field under well-watered and reproductive stage drought conditions. The resulting models displayed significantly higher predictability than multivariable models based on genomic data for the prediction of GY under drought (Q2 = 0.54–0.56 versus 0.35) and for stress-induced GY loss (Q2 = 0.59–0.64 versus 0.03–0.06). Models based on the combined datasets showed predictabilities similar to metabolic/biochemical-based models alone. In contrast to genetic markers, models with enzyme activities and metabolite values also quantitatively integrated the effect of physiological differences such as plant height on GY. The models highlighted antioxidant enzymes of the ascorbate–glutathione cycle and a lipid oxidation stress marker as important predictors of rice GY stability under drought at the reproductive stage, and these stress-related variables were more predictive than leaf central metabolites. These findings provide evidence that metabolic/biochemical traits can integrate dynamic cellular and physiological responses to the environment and can help bridge the gap between the genome and the phenome of crops as predictors of GY performance under drought.Biochemical traits outperform the explanatory power of genetic markers when used as variables in models for predicting yield performance in rice under drought stress. 相似文献
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5.
Cankar K van Houwelingen A Bosch D Sonke T Bouwmeester H Beekwilder J 《FEBS letters》2011,(1):3007-182
Chicory (Cichorium intybus L.), which is known to have a variety of terpene-hydroxylating activities, was screened for a P450 mono-oxygenase to convert (+)-valencene to (+)-nootkatone. A novel P450 cDNA was identified in a chicory root EST library. Co-expression of the enzyme with a valencene synthase in yeast, led to formation of trans-nootkatol, cis-nootkatol and (+)-nootkatone. The novel enzyme was also found to catalyse a three step conversion of germacrene A to germacra-1(10),4,11(13)-trien-12-oic acid, indicating its involvement in chicory sesquiterpene lactone biosynthesis. Likewise, amorpha-4,11-diene was converted to artemisinic acid. Surprisingly, the chicory P450 has a different regio-specificity on (+)-valencene compared to germacrene A and amorpha-4,11-diene. 相似文献
6.
The biology of strigolactones 总被引:4,自引:0,他引:4
7.
8.
Jürgen Innos Este Leidmaa Mari-Anne Philips Silva Sütt Aet Alttoa Jaanus Harro Sulev Kõks Eero Vasar 《Biochemical and biophysical research communications》2013,430(1):413-418
In mice, the limbic system-associated membrane protein (Lsamp) gene has been implicated in locomotion, anxiety, fear reaction, learning, social behaviour and adaptation. Human data links the LSAMP gene to several psychiatric disorders and completed suicide. Here, we investigated changes in major monoamine systems in mice lacking the Lsamp gene. First, the locomotor and rewarding effects of amphetamine were studied in Lsamp–/– mice and Lsamp+/+ mice. Second, monoamine levels in major brain regions in response to saline and amphetamine injections were measured and, third, the expression levels of dopamine system-related genes in the brain were studied in these mice. Lsamp–/– mice displayed lower sensitivity to amphetamine in the motility box. Likewise, in the place preference test, the rewarding effect of amphetamine was absent in Lsamp–/– mice. In all brain regions studied, Lsamp–/– mice displayed lower serotonin (5-HT) baseline levels, but a greater 5-HT turnover rate, and amphetamine increased the level of 5-HT and lowered 5-HT turnover to a greater extent in Lsamp–/– mice. Finally, Lsamp–/– mice had lower level of dopamine transporter (DAT) mRNA in the mesencephalon. In conclusion, Lsamp-deficiency leads to increased endogenous 5-HT-ergic tone and enhanced 5-HT release in response to amphetamine. Elevated 5-HT function and reduced activity of DAT are the probable reasons for the blunted effects of amphetamine in these mice. Lsamp–/– mice are a promising model to study the neurobiological mechanisms of deviant social behaviour and adaptation impairment observed in many psychiatric disorders. 相似文献
9.
Binne Zwanenburg Sandip K. Nayak Tatsiana V. Charnikhova Harro J. Bouwmeester 《Bioorganic & medicinal chemistry letters》2013,23(18):5182-5186
Strigolactones (SLs) are new plant hormones with varies important bio-functions. This Letter deals with germination of seeds of parasitic weeds. Natural SLs have a too complex structure for synthesis. Therefore, there is an active search for SL analogues and mimics with a simpler structure with retention of activity. SL analogues all contain the D-ring connected with an enone moiety through an enol ether unit. A new mechanism for the hydrolysis SL analogues involving bidentate bound water and an α,β-hydrolase with a Ser-His-Asp catalytic triad has been proposed. Newly discovered SL mimics only have the D-ring with an appropriate leaving group at C-5. A mode of action for SL mimics was proposed for which now supporting evidence is provided. As predicted an extra methyl group at C-4 of the D-ring blocks the germination of seeds of parasitic weeds. 相似文献
10.
Pseudouridine synthase RluD converts uridines at positions 1911, 1915, and 1917 of 23S rRNA to pseudouridines. These nucleotides are located in the functionally important helix-loop 69 of 23S rRNA. RluD is the only pseudouridine synthase that is required for normal growth in Escherichia coli. We have analyzed substrate specificity of RluD in vivo. Mutational analyses have revealed: (a) RluD isomerizes uridine in vivo only at positions 1911, 1915, and 1917, regardless of the presence of uridine at other positions in the loop of helix 69 of 23S rRNA variants; (b) substitution of one U by C has no effect on the conversion of others (i.e. formation of pseudouridines at positions 1911, 1915, and 1917 are independent of each other); (c) A1916 is the only position in the loop of helix 69, where mutations affect the RluD specific pseudouridine formation. Pseudouridines were determined in the ribosomal particles from a ribosomal large subunit defective strain (RNA helicase DeaD(-)). An absence of pseudouridines in the assembly precursor particles suggests that RluD directed isomerization of uridines occurs as a late step during the assembly of the large ribosomal subunit. 相似文献