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1.
Epitope mapping with a recombinant human 68-kDa (U1) ribonucleoprotein antigen reveals heterogeneous autoantibody profiles in human autoimmune sera 总被引:19,自引:0,他引:19
H H Guldner H J Netter C Szostecki H J Lakomek H Will 《Journal of immunology (Baltimore, Md. : 1950)》1988,141(2):469-475
Several cDNA fragments encoding parts of the (U1)RNP specific 68-kDa autoantigen were expressed in Escherichia coli and the fusion proteins were used as substrate for localization of the autoreactive epitopes. We have identified a region of approximately 30 amino acids reacting with more than 90% (16 of 17) of all human anti-p68 sera tested, regions which carry only a few and a region with no autoepitopes. Comparative analysis of epitopes recognized on partially degraded fusion proteins indicated that the anti-p68 autoimmune response is polyclonal. It involves generation of antibodies to several epitopes including one in a region with retroviral gag protein homology speculated to play a role in the initiation of the autoimmune response. Each of the 17 sera tested contained a different set of autoantibody specificities. These data are not consistent with random mutation as a sole mechanism of anti-p68 autoantibody induction and argue for an Ag-driven autoimmune response. 相似文献
2.
34Fusarium graminearum Schw isolates produced 4-deoxynivalenol to form significant amounts of 4, 7 — dideoxynivalenol and lesser amounts of 4 — deoxynivalenol monoacetates on grain substratesin vitro. This is the first report on the capability a large group of naturally occurring isolates to produce 4,7-dideoxynivalenol. The average levels of 4,7-dideoxynivalenol on rice, corn, barley, and wheat as a substrate were respectively 26.8, 14.0, 12.8, and 10.5% of the level of 4-deoxynivalenol. 4, 7 — dideoxynivalenol was present in all examined naturally contaminated wheat kernel samples at levels of 1.7 to 7.9% of the level of 4-deoxynivalenol. These findings suggest that more attention should be given to the occurrence of 4,7-dideoxynivalenol in cereals. 相似文献
3.
Variation in the ribosomal internal transcribed spacers (ITS1 and ITS2) among eight taxa of the Mimulus guttatus species complex 总被引:1,自引:0,他引:1
The internal transcribed spacer region (ITS1 and ITS2) of the 18S-25S
nuclear ribosomal DNA sequence and the intervening 5.8S region were
sequenced from three individuals in each of eight taxa of the Mimulus
guttatus species complex. Three discrete variants, or "types," of ITS
sequences were found, among which 30%-40% of sites differed, compared with
1%-2% within types. Dot plots indicate that these types were not related by
conspicuous rearrangements or inversions. More than one ITS type was often
found in the same taxon, and two of three ITS types span species
boundaries, indicating their presence prior to speciation. These ITS
sequences showed essentially no positional homology with the nearest
sequenced relative, tomato. In contrast, the 5.8S region was relatively
unvaried, with 8 of 162 sites varied in the sample among all eight taxa.
The phylogeny inferred by the most common ITS sequence type, rooted by the
two other ITS types, agreed with isozymes in showing the distinctness of M.
nudatus, M. laciniatus, and M. tilingii from the other five taxa.
相似文献
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Summary Double heterozygosity of pyruvate kinase (PK) deficiency associated with hereditary hemolytic anemia is emphasized by studies of a kindred harboring two distinct mutant forms of this enzyme. The hematologically unaffected parents exhibit slightly reduced PK activity, a normal Hill coefficient, and a normal thermodynamic dissociation constant for the overall reaction. The paternal enzyme is characterized by normal substrate affinities and decreased activities with the substrate analogues CDP and GDP, whereas the maternal enzyme shows normal affinity for PEP, but an increased affinity for ADP and low thermostability. It is assumed that the erythrocytes of the parents contain a mixture of normal PK and a functionally abnormal isoenzyme, the latter differing between the parents. The two children suffer from hereditary hemolytic anemia. Their PK must be a combination of the mutant paternal and maternal isoenzymes, and their activities are reduced to about 30%. These enzymes are characterized by an increased affinity for PEP and a decreased affinity for ADP, a Hill coefficient of about 1 (indicating lack of cooperativity due to a loss of its allosteric properties), a decreased overall catalytic activity, and a higher resistance to heat denaturation. Further differences are observed in the SDS-gel electrophoresis between the two patients' enzymes. From the enzymological point of view it is impossible to characterize true PK variants in such double heterozygous cases which contain a combination of two different isoenzymes. The cause of chronic hemolysis appears to depend mainly on the loss of the allosteric properties, i.e., the lack of enzyme cooperativity. 相似文献
6.
报道了小菇科小菇属真菌10个中国新记录种,香菌组:橙盖小菇Mycena aurantiidisca、黄白小菇Mycena flavoalba、粉黄小菇Mycena floridula;棘刺组:异刺小菇Mycena heteracantha;纤柄组:碱味小菇Mycena amygdalina;脆足组:粉被小菇Mycena zephirus;冬生组:绣线菊小菇Mycena speirea、冬生小菇Mycena hiemalis;小菇组:绒柄小菇Mycena flos-nivium,分别来自吉林等11个省份、自治区。提供了每个物种的形态描述和线条图,以及与相近种的讨论。共计90条自测及下载ITS序列,在采用贝叶斯法和最大似然法构建的小菇属系统发育树中,新记录种均得到分子数据支持。凭证标本存放于吉林农业大学菌物标本馆(HMJAU)。 相似文献
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本文通过Aβ25-35诱导体外原代培养的SD乳大鼠海马神经元,建立Aβ毒性损伤细胞模型,结合AnnexinV-FITC/PI荧光双染法流式细胞术、MTT比色法、实时荧光定量PCR及Western blot方法检测川芎嗪(tetrameth-ylpyrazine,TMP)对原代培养的海马神经元细胞活性、早期凋亡率和Bax、Bcl-2基因表达的影响。结果显示川芎嗪高、中剂量可明显增强细胞活性,增加神经元细胞的存活率(P<0.01),可显著抑制海马神经元细胞早期凋亡(P<0.01),抑制凋亡蛋白Bax的表达(P<0.01),增强抗凋亡蛋白bcl-2的表达(P<0.01)。川芎嗪可通过调节Bax/Bcl-2平衡抵抗Aβ25-35诱导的海马神经元凋亡,降低Aβ的神经元毒性,对海马神经元损伤有明显的保护作用。 相似文献
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