全文获取类型
收费全文 | 166篇 |
免费 | 9篇 |
出版年
2022年 | 1篇 |
2020年 | 1篇 |
2019年 | 1篇 |
2018年 | 1篇 |
2017年 | 2篇 |
2016年 | 6篇 |
2015年 | 7篇 |
2014年 | 3篇 |
2013年 | 9篇 |
2012年 | 12篇 |
2011年 | 6篇 |
2010年 | 12篇 |
2009年 | 11篇 |
2008年 | 9篇 |
2007年 | 10篇 |
2006年 | 11篇 |
2005年 | 8篇 |
2004年 | 12篇 |
2003年 | 7篇 |
2002年 | 10篇 |
2001年 | 3篇 |
2000年 | 2篇 |
1999年 | 6篇 |
1998年 | 2篇 |
1997年 | 1篇 |
1996年 | 3篇 |
1994年 | 1篇 |
1990年 | 1篇 |
1989年 | 1篇 |
1988年 | 1篇 |
1986年 | 2篇 |
1984年 | 1篇 |
1983年 | 1篇 |
1982年 | 2篇 |
1980年 | 1篇 |
1979年 | 2篇 |
1978年 | 2篇 |
1973年 | 1篇 |
1972年 | 2篇 |
1966年 | 1篇 |
排序方式: 共有175条查询结果,搜索用时 62 毫秒
81.
82.
83.
84.
Yung-Hun Yang Christopher J. Brigham Charles F. Budde Paolo Boccazzi Laura B. Willis Mohd Ali Hassan Zainal Abidin Mohd Yusof ChoKyun Rha Anthony J. Sinskey 《Applied microbiology and biotechnology》2010,87(6):2037-2045
We employed systematic mixture analysis to determine optimal levels of acetate, propionate, and butyrate for cell growth and
polyhydroxyalkanoate (PHA) production by Ralstonia eutropha H16. Butyrate was the preferred acid for robust cell growth and high PHA production. The 3-hydroxyvalerate content in the
resulting PHA depended on the proportion of propionate initially present in the growth medium. The proportion of acetate dramatically
affected the final pH of the growth medium. A model was constructed using our data that predicts the effects of these acids,
individually and in combination, on cell dry weight (CDW), PHA content (%CDW), PHA production, 3HV in the polymer, and final
culture pH. Cell growth and PHA production improved approximately 1.5-fold over initial conditions when the proportion of
butyrate was increased. Optimization of the phosphate buffer content in medium containing higher amounts of butyrate improved
cell growth and PHA production more than 4-fold. The validated organic acid mixture analysis model can be used to optimize
R. eutropha culture conditions, in order to meet targets for PHA production and/or polymer HV content. By modifying the growth medium
made from treated industrial waste, such as palm oil mill effluent, more PHA can be produced. 相似文献
85.
NUNO NEGRÕES PEDRO SARMENTO JOANA CRUZ CATARINA EIRA ELOY REVILLA CARLOS FONSECA RAHEL SOLLMANN NATÁLIA M. TǑRRES MARIANA M. FURTADO ANAH T. A. JÁCOMO LEANDRO SILVEIRA 《The Journal of wildlife management》2010,74(6):1195-1203
Abstract: We used remotely triggered cameras to collect data on Puma (Puma concolor) abundance and occupancy in an area of tropical forest in Brazil where the species' status is poorly known. To evaluate factors influencing puma occupancy we used data from 5 sampling campaigns in 3 consecutive years (2005 to 2007) and 2 seasons (wet and dry), at a state park and a private forest reserve. We estimated puma numbers and density for the 2007 sampling data by developing a standardized individual identification method. We based individual identification on 1) time-stable parameters (SP; physical features that do not change over time), and 2) time-variable parameters (VP; marks that could change over time such as scars and botfly marks). Following individual identification we established a capture-recapture history and analyzed it using closed population capture-mark-recapture models. Puma capture probability was influenced by camera placement (roads vs. trails), sampling year, and prey richness. Puma occupancy was positively associated with species richness and there was a correlation between relative puma and jaguar (Panthera onca) abundance. Identifications enabled us to generate 8 VP histories for each photographed flank, corresponding to 8 individuals. We estimated the sampled population at 9 pumas (SE = 1.03, 95% CI = 8–10 individuals) translating to a density of 3.40 pumas/100 km2. Information collected using camera-traps can effectively be used to assess puma population size in tropical forests. As habitat progressively disappears and South American felines become more vulnerable, our results support the critical importance of private forest reserves for conservation. 相似文献
86.
87.
Moon HJ Yim SV Lee WK Jeon YW Kim YH Ko YJ Lee KS Lee KH Han SI Rha HK 《Biochemical and biophysical research communications》2006,344(2):531-539
Chromosomal abnormalities are implicated as important markers for the pathogenesis in patients with schizophrenia. In this study, with using bacterial artificial chromosome (BAC) array-based comparative genomic hybridization (CGH), we analyzed DNA copy-number changes among 30 patients with schizophrenia. The most frequent changes were partial gain of Xq23 (52%) and loss of 3q13.12 (32%). Other frequent gains were found in: 1p, 6q, 10p, 11p, 11q, 14p, and 15q regions, and frequent losses were found in: 2p, 9q, 10q, 14q, 20q, and 22q regions. The set of abnormal regions was confirmed by real-time PCR (9q12, 9q34.2, 11p15.4, 14q32.33, 15q15.1, 22q11.21, and Xq23). All real-time PCR results were consistent with the array-CGH results. Therefore, it is suggested that array-CGH and real-time PCR analysis could be used as powerful tools in screening for schizophrenia-related genes. Our results might be useful for further exploration of candidate genomic regions in the pathogenesis of schizophrenia. 相似文献
88.
ANDRÉ O. SIMÕES † MARÍLIA DE M. CASTRO LUIZA S. KINOSHITA 《Botanical journal of the Linnean Society. Linnean Society of London》2006,152(3):387-398
The structure and organization of calycine colleters belonging to four genera of Apocynaceae are described. Calycine colleters were found in all species. All colleters had the same histological composition, but morphological differences were observed in four species. Most colleters were of the standard type, and possible deviations resulted in three morphological types: bifurcated, laminar, and sessile. Mechanisms of cell separation, proliferation, and elongation may explain the origin of the new types. As a consequence of morphological changes, the secretory surface was expanded in the bifurcated, laminar, and sessile glands. Most colleters were in a post-secretory phase, but a hydrophilic secretion was observed in Mandevilla pycnantha and Mesechites mansoana . A larger secretory surface, together with the extension of the secretory phase in adult flowers, were major shifts in the calycine colleters of Apocynaceae, and are possibly correlated with the functional and ecological aspects of these organs. Three patterns of distribution of calycine colleters were observed: alternate, opposite, or indefinitely distributed. The alternate pattern was not homogeneous, and three subtypes were recognized: four-, five-, and ten-grouped colleters. The number of calycine colleters was variable between taxa and even within the same species. © 2006 The Linnean Society of London, Botanical Journal of the Linnean Society , 2006, 152 , 387–398. 相似文献
89.
Riedel SL Bader J Brigham CJ Budde CF Yusof ZA Rha C Sinskey AJ 《Biotechnology and bioengineering》2012,109(1):74-83
Improved production costs will accelerate commercialization of polyhydroxyalkanoate (PHA) polymer and PHA-based products. Plant oils are considered favorable feedstocks, due to their high carbon content and relatively low price compared to sugars and other refined carbon feedstocks. Different PHA production strategies were compared using a recombinant strain of Ralstonia eutropha that produces high amounts of P(HB-co-HHx) when grown on plant oils. This R. eutropha strain was grown to high cell densities using batch, extended batch, and fed batch fermentation strategies, in which PHA accumulation was triggered by nitrogen limitation. While extended batch culture produced more biomass and PHA than batch culture, fed batch cultivation was shown to produce the highest levels of biomass and PHA. The highest titer achieved was over 139 g/L cell dry weight (CDW) of biomass with 74% of CDW as PHA containing 19 mol% HHx. Our data suggest that the fermentation process is scalable with a space time yield (STY) better than 1 g PHA/L/h. The achieved biomass concentration and PHA yield are among the highest reported for the fermentation of recombinant R. eutropha strains producing P(HB-co-HHx). 相似文献
90.
Budde CF Riedel SL Hübner F Risch S Popović MK Rha C Sinskey AJ 《Applied microbiology and biotechnology》2011,89(5):1611-1619
Polyhydroxyalkanoates (PHAs) are natural polyesters synthesized by bacteria for carbon and energy storage that also have commercial
potential as bioplastics. One promising class of carbon feedstocks for industrial PHA production is plant oils, due to the
high carbon content of these compounds. The bacterium Ralstonia eutropha accumulates high levels of PHA and can effectively utilize plant oil. Growth experiments that include plant oil, however,
are difficult to conduct in a quantitative and reproducible manner due to the heterogeneity of the two-phase medium. In order
to overcome this obstacle, a new culture method was developed in which palm oil was emulsified in growth medium using the
glycoprotein gum arabic as the emulsifying agent. Gum arabic did not influence R. eutropha growth and could not be used as a nutrient source by the bacteria. R. eutropha was grown in the emulsified oil medium and PHA production was measured over time. Additionally, an extraction method was
developed to monitor oil consumption. The new method described in this study allows quantitative, reproducible R. eutropha experiments to be performed with plant oils. The method may also prove useful for studying growth of different bacteria on
plant oils and other hydrophobic carbon sources. 相似文献