全文获取类型
收费全文 | 68篇 |
免费 | 9篇 |
专业分类
77篇 |
出版年
2023年 | 1篇 |
2019年 | 2篇 |
2018年 | 2篇 |
2016年 | 3篇 |
2014年 | 2篇 |
2013年 | 2篇 |
2012年 | 3篇 |
2010年 | 3篇 |
2009年 | 1篇 |
2008年 | 1篇 |
2007年 | 1篇 |
2005年 | 1篇 |
2004年 | 1篇 |
2003年 | 2篇 |
2001年 | 2篇 |
1999年 | 2篇 |
1998年 | 6篇 |
1997年 | 3篇 |
1996年 | 3篇 |
1995年 | 2篇 |
1994年 | 4篇 |
1993年 | 3篇 |
1992年 | 2篇 |
1991年 | 7篇 |
1990年 | 5篇 |
1989年 | 2篇 |
1988年 | 1篇 |
1987年 | 2篇 |
1986年 | 1篇 |
1985年 | 1篇 |
1984年 | 1篇 |
1982年 | 1篇 |
1981年 | 1篇 |
1980年 | 1篇 |
1977年 | 1篇 |
1975年 | 1篇 |
排序方式: 共有77条查询结果,搜索用时 15 毫秒
71.
Zimmerman PA; Katholi CR; Wooten MC; Lang-Unnasch N; Unnasch TR 《Molecular biology and evolution》1994,11(3):384-392
Polymerase chain reaction (PCR) products were characterized for a repeated
sequence family (designated "O-150") of the human filarial parasite
Onchocerca volvulus. In phylogenetic inferences, the O-150 sequences
clustered into closely related groups, suggesting that concerted evolution
maintains sequence homology in this family. Using a novel mathematical
model based on a nested application of an analysis of variance, we
demonstrated that African rainforest and savannah strain parasite
populations are significantly different. In contrast, parasites collected
in the New World are indistinguishable from African savannah strains of O.
volvulus. This finding supports the hypothesis that onchocerciasis was
recently introduced into the New World, possibly as a result of the slave
trade.
相似文献
72.
Benjamin B. Gengenbach Linda L. Keil Patrick Opdensteinen Catherine R. Müschen Georg Melmer Hans Lentzen Jens Bührmann Johannes F. Buyel 《Biotechnology and bioengineering》2019,116(9):2236-2249
Cancer is the leading cause of death in industrialized countries. Cancer therapy often involves monoclonal antibodies or small-molecule drugs, but carbohydrate-binding lectins such as mistletoe (Viscum album) viscumin offer a potential alternative treatment strategy. Viscumin is toxic in mammalian cells, ruling them out as an efficient production system, and it forms inclusion bodies in Escherichia coli such that purification requires complex and lengthy refolding steps. We therefore investigated the transient expression of viscumin in intact Nicotiana benthamiana plants and Nicotiana tabacum Bright Yellow 2 plant-cell packs (PCPs), comparing a full-length viscumin gene construct to separate constructs for the A and B chains. As determined by capillary electrophoresis the maximum yield of purified heterodimeric viscumin in N. benthamiana was ~7 mg/kg fresh biomass with the full-length construct. The yield was about 50% higher in PCPs but reduced 10-fold when coexpressing A and B chains as individual polypeptides. Using a single-step lactosyl-Sepharose affinity resin, we purified viscumin to ~54%. The absence of refolding steps resulted in estimated cost savings of more than 80% when transient expression in tobacco was compared with E. coli. Furthermore, the plant-derived product was ~3-fold more toxic than the bacterially produced counterpart. We conclude that plants offer a suitable alternative for the production of complex biopharmaceutical proteins that are toxic to mammalian cells and that form inclusion bodies in bacteria. 相似文献
73.
Association of a major groat oil content QTL and an acetyl-CoA carboxylase gene in oat 总被引:2,自引:0,他引:2
S. F. Kianian M. A. Egli R. L. Phillips H. W. Rines D. A. Somers B. G. Gengenbach F. H. Webster S. M. Livingston S. Groh L. S. O’Donoughue M. E. Sorrells D. M. Wesenberg D. D. Stuthman R. G. Fulcher 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1999,98(6-7):884-894
Oat groats are unique among cereals for the high level and the embryo-plus-endosperm localization of lipids. Genetic manipulation
of groat quality traits such as oil is desired for optimizing the value of oat in human and livestock diets. A locus having
a major effect on oil content in oat groats was located on linkage group 11 by single-factor analysis of variance, simple
interval mapping and simplified composite interval mapping. A partial oat cDNA clone for plastidic acetyl-CoA carboxylase
(ACCase), which catalyzes the first committed step in de novo fatty acid synthesis, identified a polymorphism linked to this
major QTL. Similar QTL and ACCase locus placements were obtained with two recombinant inbred populations, ‘Kanota’בOgle’
(KO) and ‘Kanota’בMarion’ (KM), containing 137 and 139 individual lines, respectively. By having a common parent these populations
provide biological replication of the results in that significant genomic regions should be evident in analyses of multiple
cross combinations. The KO population was mapped with 150 RFLP loci distributed over the genome and was grown in five diverse
environments (locations and years) for measurement of groat oil content. The KM population was mapped with 60 RFLP loci and
grown in three environments. The QTL linked to AccaseA on linkage group 11 accounted for up to 48% of the phenotypic variance for groat oil content. These results provide strong
support for the hypothesis that ACCase has a major role in determining groat oil content. Other QTLs were identified in both
populations which accounted for an additional 10–20% of the phenotypic variance.
Received: 2 July 1998 / Accepted: 3 November 1998 相似文献
74.
Thomas D. Pfister Amir Y. Mirarefi Alan J. Gengenbach Xuan Zhao Connor Danstrom Nicole Conatser Yi-Gui Gao Howard Robinson Charles F. Zukoski Andrew H.-J. Wang Yi Lu 《Journal of biological inorganic chemistry》2007,12(1):126-137
Manganese peroxidase (MnP) from the white rot fungus Phanerochaete chrysosporium contains a manganese-binding site that plays a critical role in its function. Previously, a MnII-binding site was designed into cytochrome c peroxidase (CcP) based on sequence homology (Yeung et al. in Chem. Biol. 4:215–222, 1997; Gengenbach et al. in Biochemistry 38:11425–11432, 1999). Here, we report a redesign of this site based on X-ray structural comparison of MnP and CcP. The variant, CcP(D37E, V45E, H181E), displays 2.5-fold higher catalytic efficiency (k
cat/K
M) than the variant in the original design, mostly due to a stronger K
M of 1.9 mM (vs. 4.1 mM). High-resolution X-ray crystal structures of a metal-free form and a form with CoII at the designed MnII site were also obtained. The metal ion in the engineered metal-binding site overlays well with MnII bound in MnP, suggesting that this variant is the closest structural model of the MnII-binding site in MnP for which a crystal structure exists. A major difference arises in the distances of the ligands to the
metal; the metal–ligand interactions in the CcP variant are much weaker than the corresponding interactions in MnP, probably owing to partial occupancy of metal ion at
the designed site, difference in the identity of metal ions (CoII rather than MnII) and other interactions in the second coordination sphere. These results indicate that the metal ion, the ligands, and the
environment around the metal-binding site play important roles in tuning the structure and function of metalloenzymes.
Electronic supplementary material Supplementary material is available in the online version of this article at and is accessible for authorized users. 相似文献
75.
A simple equipment was developed to cultivate young cereal plants under enhanced CO2 concentration. Cultivation system permits growing of about 40 barley seedlings for about 2 to 3 weeks. The system consists
of two identical growth chambers (volume about 30 dm3), gas conditioning circuit and measuring circuit with an infra-red CO2 analyser. Capabilities of the whole equipment were tested by growing barley plants under 330 and 1000 cm3 (CO2)m−3 and in combination with high or low nitrate level. 相似文献
76.
77.