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71.
Summary In the qualitative short-day plant Impatiens balsamina, gibberellic acid (GA3) not only promoted the formation of floral buds in response to suboptimal photoinductive conditions and reduced the number of SD cycles that are required for their development into flowers, but also caused initiation of floral buds under non-inductive photoperiods. In plants treated with repeated applications of GA3, the floral buds developed into flowers irrespective of whether the apex was left intact or was removed. In those that received a single application of GA3 the floral buds developed into flowers only in decapitated plants. 相似文献
72.
Silva WA Bortolini MC Schneider MP Marrero A Elion J Krishnamoorthy R Zago MA 《Human biology; an international record of research》2006,78(1):29-41
Seventy individuals from two African and four black Brazilian populations were studied for the first hypervariable segment of mtDNA. To delineate a more complete phylogeographic scenario of the African mtDNA haplogroups in Brazil and to provide additional information on the nature of the Atlantic slave trade, we analyzed our data together with previously published data. The results indicate different sources of African slaves for the four major Brazilian regions. In addition, the data revealed patterns that differ from those expected on the basis of historical registers, thus suggesting the role of ethnic sex differences in the slave trade. 相似文献
73.
The sodium dodecyl sulfate driven dissociation reactions of daunorubicin (1), mitoxantrone (2), ametantrone (3), and a related anthraquinone without hydroxyl groups on the ring or side chain (4) from calf thymus DNA, poly[d(G-C)]2, and poly[d(A-T)]2 have been investigated by stopped-flow kinetic methods. All four compounds exhibit biphasic dissociation reactions from their DNA complexes. Daunorubicin and mitoxantrone have similar dissociation rate constants that are lower than those for ametantrone and 4. The effect of temperature and ionic strength on both rate constants for each compound is similar. An analysis of the effects of salt on the two rate constants for daunorubicin and mitoxantrone suggests that both of these compounds bind to DNA through a mechanism that involves formation of an initial outside complex followed by intercalation. The daunorubicin dissociation results from both poly[d(G-C)]2 and poly[d(A-T)]2 can be fitted with a single exponential function, and the rate constants are quite close. The ametantrone and 4 polymer dissociation results can also be fitted with single exponential curves, but with these compounds the dissociation rate constants for the poly[d(G-C)]2 complexes are approximately 10 times lower than for the poly[d(A-T)]2 complexes. Mitoxantrone also has a much slower dissociation rate from poly[d(G-C)]2 than from poly[d(A-T)]2, but its dissociation from both polymers exhibits biphasic kinetics. Possible reasons for the biphasic behavior with the polymers, which is unique to mitoxantrone, are selective binding and dissociation from the alternating polymer intercalation sites and/or dual binding modes of the intercalator with both side chains in the same groove or with one side chain in each groove. 相似文献
74.
The literature data on the activity of histidine-15 modified hen egg white lysozyme are conflicting: the modified enzyme is
reported to have more activity, similar activity or less activity by different authors. Amino acid analysis had shown modification
of the single His-15. Detailed activity studies on His-15-modified (by iodoacetic acid or diethyl pyrocarbonate) lysozyme
have shown that the contradicting reports are due to the specific choices of ionic strengths and cell wall substrate concentrations
and can be attributed to the substrate being negatively charged. Our analysis suggests that even though histidine-15 is far
removed from the active site of lysozyme, its chemical modification or binding of the negatively-charged substrate near it,
changes the conformation around the active site. However, the change in the optimum activity on chemically modifying His-15
is small. 相似文献
75.
Guy Trabuchet Jacques Elion Olga Dunda Claudine Lapouméroulie Rolande Ducrocq Sellama Nadifi Isidore Zohoun Andre Chaventre Pierre Carnevale Ronald L. Nagel Rajagopal Krishnamoorthy Dominique Labie 《Human genetics》1991,87(5):597-601
Summary The origin of the C mutation was studied by characterizing nucleotide sequence polymorphisms on C chromosomes of patients from various African countries. In the majority of cases, the C mutation was found in linkage disequilibrium with a single chromosomal structure as defined by classical RFLP haplotypes, intergenic nucleotide sequence polymorphisms immediately upstream of the -globin gene, and intragenic -globin gene polymorphisms (frameworks). In addition, three atypical variant chromosomes carrying the C mutation were observed, and are most probably explained either by a meiotic recombination (two cases) or by one nucleotide substitution occurring in an unstable array of tandemly repeated sequences (one case). These data demonstrate the unicentric origin of the C mutation in central West Africa, with subsequent mutational modification in a small number of instances. The data also supports gene flow of the C chromosome from subsaharan Africa to North Africa. 相似文献
76.
A novel beta thalassemia gene with a single base mutation in the conserved polypyrimidine sequence at the 3' end of IVS 2 总被引:4,自引:1,他引:3 下载免费PDF全文
C Beldjord C Lapoumeroulie J Pagnier M Benabadji R Krishnamoorthy D Labie A Bank 《Nucleic acids research》1988,16(11):4927-4935
An adult Algerian patient with homozygous beta thalassemia was found to have a unique beta thalassemia gene. Cloning and sequencing revealed that the only abnormality present in this beta gene is a transversion in the polypyrimidine stretch at the 3' end of the large intervening sequence (IVS 2) six bases 5' to the consensus AG dinucleotide sequence (CCGCCCACAG instead of CCTCCCACAG). In addition, digestion of the cloned fragment by the enzyme Mnl I demonstrates the disappearance of a restriction site as expected. This is the first example of a defect in the consensus sequence at the 3' end of an IVS leading to a thalassemia phenotype presumably due to decreased splicing. 相似文献
77.
The nature of codon 57 in the HLA-DQ beta gene was recently reported as a potential marker of genetic susceptibility to insulin-dependent diabetes mellitus. When exploring the relevance of this marker by using genomic DNA amplification, we encountered difficulties resulting from the coamplification of the homologous DX beta region. A simple strategy is proposed to amplify the DQ beta region exclusively. It involves the preliminary digestion of genomic DNA with a restriction enzyme which cleaves DX beta specifically, leaving intact the DQ beta sequence. The amplified material is suitable for dot blot analysis and restriction enzyme digestion. This strategy is of general interest when homologous sequences impair the specificity of enzymatic DNA amplification. 相似文献
78.
79.