全文获取类型
收费全文 | 795篇 |
免费 | 35篇 |
国内免费 | 17篇 |
出版年
2023年 | 8篇 |
2022年 | 7篇 |
2021年 | 13篇 |
2020年 | 10篇 |
2019年 | 15篇 |
2018年 | 19篇 |
2017年 | 16篇 |
2016年 | 13篇 |
2015年 | 19篇 |
2014年 | 31篇 |
2013年 | 49篇 |
2012年 | 19篇 |
2011年 | 34篇 |
2010年 | 24篇 |
2009年 | 34篇 |
2008年 | 36篇 |
2007年 | 32篇 |
2006年 | 45篇 |
2005年 | 37篇 |
2004年 | 38篇 |
2003年 | 29篇 |
2002年 | 37篇 |
2001年 | 14篇 |
2000年 | 22篇 |
1999年 | 17篇 |
1998年 | 21篇 |
1997年 | 18篇 |
1996年 | 24篇 |
1995年 | 12篇 |
1994年 | 23篇 |
1993年 | 11篇 |
1992年 | 6篇 |
1991年 | 10篇 |
1990年 | 8篇 |
1989年 | 8篇 |
1988年 | 10篇 |
1987年 | 8篇 |
1986年 | 5篇 |
1985年 | 18篇 |
1984年 | 10篇 |
1983年 | 6篇 |
1982年 | 9篇 |
1981年 | 4篇 |
1980年 | 6篇 |
1979年 | 4篇 |
1978年 | 2篇 |
1977年 | 4篇 |
1974年 | 2篇 |
排序方式: 共有847条查询结果,搜索用时 93 毫秒
61.
Regulation of Glc7 type 1 protein phosphatase stability and activity was studied in budding yeast. We found that the Glc7 protein has a half-life of over 180min, which is sufficient for several generations. Glc7 protein stability was constant during the cell cycle and in batch culture growth. Furthermore, deletion of regulatory subunit Gac1, Reg1, Reg2, Sds22, or Glc8 had no influence on Glc7 protein half-life. The activity of Glc7 assayed as okadaic acid-resistant phosphorylase phosphatase activity was constant during the cell cycle. Deletion of the aforementioned regulatory subunits revealed that only Glc8 deletion had a significant effect in reducing Glc7 activity. Glc7 activity was induced during stationary phase in a Glc8-dependent manner. In addition, extracellular glucose repressed the induction of Glc7 activity. These results are consistent with glucose repression of Glc8 expression and favor the role of Glc8 as a major Glc7 activator. 相似文献
62.
63.
64.
Mahr K van Wezel GP Svensson C Krengel U Bibb MJ Titgemeyer F 《Antonie van Leeuwenhoek》2000,78(3-4):253-261
Glucose kinase of Streptomyces coelicolor A3(2) is essential for glucose utilisation and is required for carbon catabolite repression (CCR) exerted through glucose and other carbon sources. The protein belongs to the ROK-family, which comprises bacterial sugar kinases and regulators. To better understand glucose kinase function, we have monitored the cellular activity and demonstrated that the choice of carbon sources did not significantly change the synthesis and activity of the enzyme. The DNA sequence of the Streptomyces lividans glucose kinase gene glkA was determined. The predicted gene product of 317 amino acids was found to be identical to S. coelicolor glucose kinase, suggesting a similar role for this protein in both organisms. A procedure was developed to produce pure histidine-tagged glucose kinase with a yield of approximately 10 mg/l culture. The protein was stable for several weeks and was used to raise polyclonal antibodies. Purified glucose kinase was used to explore protein-protein interaction by surface plasmon resonance. The experiments revealed the existence of a binding activity present in S. coelicolor cell extracts. This indicated that glucose kinase may interact with (an)other factor(s), most likely of protein nature. A possible cross-talk with proteins of the phosphotransferase system, which are involved in carbon catabolite repression in other bacteria, was investigated. 相似文献
65.
66.
67.
Transgenic tobacco (Nicotiana tabacum L.) plants with decreased and increased transport capacities of the chloroplast triose phosphate/phosphate translocator (TPT)
were used to study the control the TPT exerts on the flux of starch and sucrose biosynthesis, as well as CO2 assimilation, respiration and photosynthetic electron transport. For this purpose, tobacco lines with an antisense repression
of the endogenous TPT (αTPT) and tobacco lines overexpressing a TPT gene from Flaveria trinervia (FtTPT) were used. In ambient CO2, there was no or little effect of altered TPT transport activities on either rates of photosynthetic electron transport and/or
CO2 assimilation. However, in elevated CO2 (1500 μl · l−1) and low O2 (2%) the TPT exerted strong control on the rate of CO2 assimilation (control coefficient for the wild type; CJA
TPT=0.30) in saturating light. Similarly, the incorporation of 14C into starch in high CO2 was increased in tobacco plants with decreased TPT activity, but was reduced in plants overexpressing the TPT from F. trinervia. Thus, the TPT exerted negative control on the rate of starch biosynthesis with a CJStarch
TPT=−0.19 in the wild type estimated from a hyperbolic curve fitted to the data points. This was less than the positive control
strength on the rate of sucrose biosynthesis (CJSuc
TPT=0.35 in the wild type). Theoretically, the positive control exerted on sucrose biosynthesis should be numerically identical
to the negative control on starch biosynthesis unless additional metabolic pathways are affected. The rate of dark respiration
showed some correlation with the TPT activity in that it increased in FtTPT overexpressors, but decreased in αTPT plants with
an apparent control coefficient of CJRes
TPT=0.24. If the control on sucrose biosynthesis is referred to as “gain of carbon” (positive control) and the control on starch
biosynthesis as well as dark respiration as a “loss of carbon” (negative control) for sucrose biosynthesis and subsequent
export, the sum of the control coefficients on dark respiration and starch biosynthesis would be numerically similar to the
control coefficient on the rate of sucrose biosynthesis. There was also some control on the rate of photosynthetic electron
transport, but only at high light and in elevated CO2 combined with low O2. The control coefficient for the rate of photosynthetic electron transport was CJETR
TPT=0.16 in the wild type. Control coefficients were also calculated for plants with elevated and lowered TPT activity. Furthermore,
the extent to which starch degradation/glucose utilisation compensates for the lack of triose phosphate export was assessed.
The TPT also exerted control on metabolite contents in air.
Received: 26 March 1999 / Accepted: 21 August 1999 相似文献
68.
Regulation of primary carbon metabolism in Kluyveromyces lactis 总被引:2,自引:0,他引:2
Breunig KD Bolotin-Fukuhara M Bianchi MM Bourgarel D Falcone C Ferrero I Frontali L Goffrini P Krijger JJ Mazzoni C Milkowski C Steensma HY Wésolowski-Louvel M Zeeman AM 《Enzyme and microbial technology》2000,26(9-10):771-780
In the recent past, through advances in development of genetic tools, the budding yeast Kluyveromyces lactis has become a model system for studies on molecular physiology of so-called “Nonconventional Yeasts.” The regulation of primary carbon metabolism in K. lactis differs markedly from Saccharomyces cerevisiae and reflects the dominance of respiration over fermentation typical for the majority of yeasts. The absence of aerobic ethanol formation in this class of yeasts represents a major advantage for the “cell factory” concept and large-scale production of heterologous proteins in K. lactis cells is being applied successfully. First insight into the molecular basis for the different regulatory strategies is beginning to emerge from comparative studies on S. cerevisiae and K. lactis. The absence of glucose repression of respiration, a high capacity of respiratory enzymes and a tight regulation of glucose uptake in K. lactis are key factors determining physiological differences to S. cerevisiae. A striking discrepancy exists between the conservation of regulatory factors and the lack of evidence for their functional significance in K. lactis. On the other hand, structurally conserved factors were identified in K. lactis in a new regulatory context. It seems that different physiological responses result from modified interactions of similar molecular modules. 相似文献
69.
Metabolic engineering has become a very important approach to strain improvement in parallel with classical strain development. Although Saccharomyces cerevisiae has been domesticated for ethanol and bread production, there are still some fundamental problems associated with its industrial use. The industrially used carbon sources often consist of a sugar mixture, and due to glucose repression these sugars are utilized sequentially, resulting in prolonged production time. In this article we discuss the application of metabolic engineering for construction of glucose-derepressed strains and specify advantages as well as difficulties associated with this approach. 相似文献
70.