全文获取类型
收费全文 | 1160篇 |
免费 | 92篇 |
出版年
2022年 | 5篇 |
2021年 | 10篇 |
2019年 | 8篇 |
2018年 | 13篇 |
2017年 | 17篇 |
2016年 | 26篇 |
2015年 | 43篇 |
2014年 | 45篇 |
2013年 | 50篇 |
2012年 | 62篇 |
2011年 | 75篇 |
2010年 | 43篇 |
2009年 | 63篇 |
2008年 | 53篇 |
2007年 | 71篇 |
2006年 | 53篇 |
2005年 | 56篇 |
2004年 | 56篇 |
2003年 | 60篇 |
2002年 | 69篇 |
2001年 | 20篇 |
2000年 | 20篇 |
1999年 | 10篇 |
1998年 | 15篇 |
1997年 | 14篇 |
1996年 | 12篇 |
1995年 | 11篇 |
1994年 | 8篇 |
1993年 | 12篇 |
1992年 | 13篇 |
1991年 | 13篇 |
1990年 | 6篇 |
1989年 | 9篇 |
1988年 | 9篇 |
1987年 | 8篇 |
1986年 | 4篇 |
1985年 | 8篇 |
1984年 | 9篇 |
1982年 | 7篇 |
1981年 | 7篇 |
1980年 | 4篇 |
1979年 | 8篇 |
1975年 | 4篇 |
1908年 | 4篇 |
1888年 | 10篇 |
1887年 | 11篇 |
1886年 | 16篇 |
1885年 | 12篇 |
1884年 | 8篇 |
1858年 | 3篇 |
排序方式: 共有1252条查询结果,搜索用时 62 毫秒
21.
Isolation and characterization of nuclear genes coding for subunits of the yeast ubiquinol-cytochrome c reductase complex 总被引:9,自引:0,他引:9
Adolphus P.G.M. van Loon Raoul J. de Groot Ed van Eyk Gijsbertus T.J. van der Horst Leslie A. Grivell 《Gene》1982,20(3):323-337
Nuclear genes coding for the Mr 17000, 14000 and 11000 subunits of the ubiquinol-cytochrome c reductase complex (complex III) in yeast have been isolated from a clone bank of yeast nuclear DNA by use of a mRNA hybridization-competition assay. This is based on our observations that levels of mRNAs for these subunits are much reduced during glucose repression and in cytoplasmic petite mutants and the procedure should be of general application for the isolation of other inducible or repressible genes coding for mRNAs present at low levels in the cell. A first characterization of the clones is presented. The genes are not closely linked in the genome and those coding for Mr 14000 and 11000 subunits are present in unique genomic environments, which suggests that there are only single copies of each in the nuclear genome. 相似文献
22.
Neutralization of native human gamma interferon (HuIFN gamma) by antibodies to a synthetic peptide encoded by the 5' end of HuIFN gamma cDNA 总被引:8,自引:0,他引:8
H M Johnson M P Langford B Lakhchaura T S Chan G J Stanton 《Journal of immunology (Baltimore, Md. : 1950)》1982,129(6):2357-2359
A synthetic peptide corresponding to the N-terminal amino acid sequence of human gamma-interferon (HuIFN gamma), based on the cDNA sequence, was used to produce antibodies in rabbits that were reactive with native HuIFN gamma. Antibodies from all immunized rabbits neutralized the antiviral activity of HuIFN gamma. Significant neutralization of other HuIFN and mouse IFN was not observed. The peptide had the sequence Cys-Tyr-Cys-Gln-Asp-Pro-Tyr-Val-Lys-Glu-Ala-Glu-Asn-Leu-Lys-Lys-Tyr-Phe-Asn-Ala ,and was coupled to keyhole limpet hemocyanin by disulfide linkage with the use of cystamine. The specificity of the antibodies produced to the peptide was compared to that of antibodies produced to native HuIFN gamma by neutralization of HuIFN gamma and by reactivity with peptide in the enzyme-linked immunosorbent assay (ELISA). The ratio of anti-peptide antibody neutralization of HuIFN gamma vs reactivity with peptide in the ELISA was at least 28-fold lower than for anti-HuIFN gamma antibody. Thus the antibodies to peptide and to HuIFN gamma were directed primarily against different determinants on native HuIFN gamma or the anti-HuIFN gamma antiserum probably contained antibodies to additional determinants. The anti-peptide antibodies should be useful for further characterization and purification of HuIFN gamma. 相似文献
23.
General patterns of sucrose fermentation by two strains of Zymomonas mobilis, designated Z7 and Z10, were established using sucrose concentrations from 50 to 200 g/liter. Strain Z7 showed a higher invertase activity than Z10. Strain Z10 showed a reduced specific growth rate at high sucrose concentration while Z7 was unaffected. High sucrose hydrolyzing activity in strain Z7 lead to glucose accumulation in the medium at high sucrose concentrations. Ethanol production and fermentation time depend on the rate of catabolism of the products of sucrose hydrolysis, glucose and fructose. The metabolic quotients for sucrose utilization, qs, and ethanol production, qp (g/g·hr), are unsuitable for describing sucrose utilization by Zymomonas mobilis, as the logarithmic phase of growth precedes the phase of highest substrate utilization (g/liter·hr) and ethanol production (g/liter·hr) in batch culture. 相似文献
24.
Nonsensitized lymphocytes produce leukocyte interferon when cultured with foreign cells. 总被引:5,自引:0,他引:5
Nonsensitized human lymphocytes produce interferon when cultured with either transformed or normal heterologous cells. De novo RNA and protein synthesis was not required in a foreign cell for it to act as the inducer. The interferon produced has been characterized as being leukocyte type rather than immune or fibroblast type. 相似文献
25.
26.
Dr. Ed. Formánek 《Plant Systematics and Evolution》1884,34(9):322-327
Ohne Zusammenfassung 相似文献
27.
Ed. Palla 《Plant Systematics and Evolution》1886,36(3):85-87
Ohne Zusammenfassung 相似文献
28.
Immunoglobulins were measured in colostral whey from untreated ewes or ewes treated on days 142-145 of gestation with 15 mg oestradiol benzoate (ODB) or 10, 17.5 or 25 mg dexamethasone m-sulfobenzoate (DEX) to induce parturition. DEX at all levels reduced the concentrations of immunoglobulins in colostrum, but ODB had no effect. In a second experiment, similar treatments of ODB and DEX were applied on day 143 of gestation. Lambs were removed from their dams at birth and fed a standard volume of pooled colostrum taken from untreated ewes. They were injected with an antigen (Brucella abortus) at 12 h and 4 weeks of age. Concentrations of immunoglobulins in blood plasma at 24 h after birth of lambs from DEX-treated ewes were lower than for lambs from untreated ewes or from those treated with ODB. Response to the antigen, monitored to 12 weeks of age, was unaffected by either drug. The impairment of transfer of immunoglobulins from ewe to lamb offers a possible explanation for the higher mortality among older lambs found previously after treatment of ewes with DEX. 相似文献
29.
Samin Hosseini Ed D. L. Schmidt Freek T. Bakker 《The Plant journal : for cell and molecular biology》2020,103(2):547-560
Receptor‐like kinases (RLKs) represent the largest group of cell surface receptors in plants. The monophyletic leucine‐rich repeat (LRR)‐RLK subfamily II is considered to contain the somatic embryogenesis receptor kinases (SERKs) and NSP‐interacting kinases known to be involved in developmental processes and cellular immunity in plants. There are only a few published studies on the phylogenetics of LRR‐RLKII; unfortunately these suffer from poor taxon/gene sampling. Hence, it is not clear how many and what main clades this family contains, let alone what structure–function relationships exist. We used 1342 protein sequences annotated as ‘SERK’ and ‘SERK‐like’ plus related sequences in order to estimate phylogeny within the LRR‐RLKII clade, using the nematode protein kinase Pelle as an outgroup. We reconstruct five main clades (LRR‐RLKII 1–5), in each of which the main pattern of land plant relationships re‐occurs, confirming previous hypotheses that duplication events happened in this gene subfamily prior to divergence among land plant lineages. We show that domain structures and intron–exon boundaries within the five clades are well conserved in evolution. Furthermore, phylogenetic patterns based on the separate LRR and kinase parts of LRR‐RLKs are incongruent: whereas the LRR part supports a LRR‐RLKII 2/3 sister group relationship, the kinase part supports clades 1/2. We infer that the kinase part includes few ‘radical’ amino acid changes compared with the LRR part. Finally, our results confirm that amino acids involved in each LRR‐RLKII–receptor complex interaction are located at N‐capping residues, and that the short amino acid motifs of this interaction domain are highly conserved throughout evolution within the five LRR‐RLKII clades. 相似文献
30.