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Bacterial cells often contain dense granules. Among these, polyphosphate bodies (PPBs) store inorganic phosphate for a variety of essential functions. Identification of PPBs has until now been accomplished by analytical methods that required drying or chemically fixing the cells. These methods entail large electron doses that are incompatible with low‐dose imaging of cryogenic specimens. We show here that Scanning Transmission Electron Microscopy (STEM) of fully hydrated, intact, vitrified bacteria provides a simple means for mapping of phosphorus‐containing dense granules based on quantitative sensitivity of the electron scattering to atomic number. A coarse resolution of the scattering angles distinguishes phosphorus from the abundant lighter atoms: carbon, nitrogen and oxygen. The theoretical basis is similar to Z contrast of materials science. EDX provides a positive identification of phosphorus, but importantly, the method need not involve a more severe electron dose than that required for imaging. The approach should prove useful in general for mapping of heavy elements in cryopreserved specimens when the element identity is known from the biological context. 相似文献
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利用根癌农杆菌LBA4404介导,将编码透明颤菌血红蛋白的结构基因(Vitreoscilla Hemoglobin gene,vgb)导入到短密青霉ATCC16024中,用于改善菌体对氧的摄取能力,提高霉酚酸(Myhophenoilc Acid,MPA)的发酵水平,降低生产成本。通过潮霉素抗性筛选、PCR分子鉴定和MPA发酵验证等结果表明,vgb基因在短密青霉中成功获得了表达;vgb基因的表达提高了短密青霉的菌体密度,转化子MPA产量达到2.18 g·L?1,比原始菌株提高了27.5%。 相似文献
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Gaoyang Zhang Yujia Zhang Jiantang Xu Feng Tao Li Aifen Tao Liwu Zhang 《Journal of Natural Fibers》2015,12(4):303-310
The purpose of this study was to use cotyledonary nodes as explants to establish an efficient regeneration protocol for jute (Corchorus capsularis L.) on Murashige and Skoog (MS) basal medium. Research into the different growth regulators using the orthogonal design L16 (45) revealed that the best shoot induction medium is MS medium containing 8% (w/v) agar and 3% (w/v) sucrose supplemented with 1.0 mg/L 6BA and 0.25 mg/L NAA. The average number of shoots per explant and the explant induction rate were 9.8 and 100%. After 3 weeks, 2–3 cm shoots were rooting on 1/2 MS medium containing 8% (w/v) agar and 3% (w/v) sucrose supplemented with 1.0 mg/L 6-BA + 0.2 mg/L NAA. Moreover, we optimized Agrobacterium-mediated transformation using the GUS gene transient expression system. The best condition for obtaining higher transformation rate consisted of the use of fresh explants to which 100 μM acetosyringone was added for a co-culture time of 10 min, the OD value of Agrobacterium liquid is 0.5 at 600 nm. These data provide an important basis for the application of other trait gene in the improvement of jute fiber quality. 相似文献
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Fernando Perez Rojo Sumedha Seth William Erskine Parwinder Kaur 《International journal of molecular sciences》2021,22(8)
Subterranean clover (Trifolium subterraneum) is the most widely grown annual pasture legume in southern Australia. With the advent of advanced sequencing and genome editing technologies, a simple and efficient gene transfer protocol mediated by Agrobacterium tumefaciens was developed to overcome the hurdle of genetic manipulation in subterranean clover. In vitro tissue culture and Agrobacterium transformation play a central role in testing the link between specific genes and agronomic traits. In this paper, we investigate a variety of factors affecting the transformation in subterranean clover to increase the transformation efficiency. In vitro culture was optimised by including cefotaxime during seed sterilisation and testing the best antibiotic concentration to select recombinant explants. The concentrations for the combination of antibiotics obtained were as follows: 40 mg L−1 hygromycin, 100 mg L−1 kanamycin and 200 mg L−1 cefotaxime. Additionally, 200 mg L−1 cefotaxime increased shoot regeneration by two-fold. Different plant hormone combinations were tested to analyse the best rooting media. Roots were obtained in a medium supplemented with 1.2 µM IAA. Plasmid pH35 containing a hygromycin-resistant gene and GUS gene was inoculated into the explants with Agrobacterium tumefaciens strain AGL0 for transformation. Overall, the transformation efficiency was improved from the 1% previously reported to 5.2%, tested at explant level with Cefotaxime showing a positive effect on shooting regeneration. Other variables in addition to antibiotic and hormone combinations such as bacterial OD, time of infection and incubation temperature may be further tested to enhance the transformation even more. This improved transformation study presents an opportunity to increase the feeding value, persistence, and nutritive value of the key Australian pasture. 相似文献
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研究了溶剂种类、浓度,提取溶剂比例、提取次数、时间、温度,萃取次数与温度,以及柱纯化和重结晶等条件对提取农杆菌中辅酶Q_(10)的影响;进行了最佳工艺优化,确立了生产工艺,并进行了中试验证.结果表明,最佳工艺条件为:用5倍的体积分数95%的乙醇在50℃浸提2遍,每遍1 h,获得提取液;提取液浓缩后经过提取液-甲醇-石油醚(三者体积比为1:2:3)的萃取体系室温萃取3遍,浓缩石油醚相后经过1步硅胶层析柱纯化,2或3步乙醇重结晶.中试结果表明,该工艺获得辅酶Q_(10)的纯度>99%,平均回收率>80%. 相似文献
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Characterization of curdlan produced by Agrobacterium sp. IFO 13140 cells immobilized in a loofa sponge matrix,and application of this biopolymer in the development of functional yogurt
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