全文获取类型
收费全文 | 600篇 |
免费 | 32篇 |
专业分类
632篇 |
出版年
2023年 | 1篇 |
2022年 | 8篇 |
2021年 | 13篇 |
2020年 | 8篇 |
2019年 | 12篇 |
2018年 | 20篇 |
2017年 | 23篇 |
2016年 | 28篇 |
2015年 | 29篇 |
2014年 | 42篇 |
2013年 | 44篇 |
2012年 | 55篇 |
2011年 | 52篇 |
2010年 | 26篇 |
2009年 | 39篇 |
2008年 | 24篇 |
2007年 | 30篇 |
2006年 | 31篇 |
2005年 | 39篇 |
2004年 | 28篇 |
2003年 | 32篇 |
2002年 | 27篇 |
2001年 | 3篇 |
2000年 | 2篇 |
1999年 | 3篇 |
1998年 | 3篇 |
1997年 | 2篇 |
1996年 | 2篇 |
1995年 | 1篇 |
1994年 | 2篇 |
1993年 | 2篇 |
1992年 | 1篇 |
排序方式: 共有632条查询结果,搜索用时 0 毫秒
131.
132.
133.
134.
Tamara I. Balakhnina Vladimir V. Matichenkov Teresa Wlodarczyk Aneta Borkowska Magdalena Nosalewicz Irina R. Fomina 《Plant Growth Regulation》2012,67(1):35-43
Barley (Hordeum vulgare L.) was grown in pots with brown loess soil and highly soluble amorphous silicon dioxide as the source of monosilicic acid
to examine its influence on plant growth and adaptive potential under optimal soil watering and flooding. The adaptive potential
of plants was estimated by the concentration of the thiobarbituric acid reactive substances (TBARs) as well as superoxide
dismutase (SOD), guaiacol peroxidase (GPX) and ascorbate peroxidase (AsP) activities. Application of amorphous silica to the
soil increased the Si content in barley shoots and roots and stimulated their growth and biomass production under optimal
soil watering. Soil flooding suppressed the growth both of the (−Si)- and (+Si)-plants. The intensity of oxidative destruction
estimated by the concentration of TBARs was lower in the roots and leaves of the (+Si)-plants. Soil flooding induced SOD activity
in the roots and in the leaves of the (−Si;+flooding) and (+Si;+flooding)-plants, but no significant differences were observed
due to the Si treatment. GPX activity in the roots of (+Si)-plants was higher than in the (−Si)-ones under optimal soil watering,
but under soil flooding no differences between (+Si)- and (−Si)-treatments were observed. AsP activity was not influenced
by Si treatment neither under optimal soil watering nor under flooding. Thus, application of Si stimulates growth processes
of barley shoots and roots under optimal soil watering and decreases intensity of oxidative destruction under soil flooding
without significant changes in the activities of antioxidant enzymes. 相似文献
135.
Tadeusz Włostowski Alicja Krasowska Aneta Salińska Monika Włostowska 《Biological trace element research》2009,131(3):291-297
The objective of this study was to examine relations between body iron (Fe) status and cadmium (Cd) accumulation in a small
rodent, the bank vole, caught from the wild population in late autumn (November) and early spring (March). The concentrations
of Fe in the liver, kidneys, and duodenum in the bank voles from the spring were only 30%, 60%, and 70%, respectively, of
those found in the animals from the autumn. An analysis of hematocrit and hemoglobin content of blood showed no significant
effect of the season, suggesting that the animals from the spring were not anemic. The exposure to dietary Cd (10 μg/g) for
7 days resulted in 70% higher accumulation of Cd in the liver and kidneys of the spring than autumn bank voles, and the concentration
of Cd in the duodenum was 3.5 times higher in the spring animals, despite the fact that relative Cd intake was significantly
higher in the autumn bank voles. The data indicate that seasonal changes of body Fe status occurring in the wild bank voles
may influence tissue accumulation of Cd. 相似文献
136.
Weryszko-Chmielewska Elżbieta Sulborska-Różycka Aneta Sawidis Thomas 《Protoplasma》2022,259(6):1467-1476
Protoplasma - Chaenomeles japonica is an attractive ornamental shrub flowering in spring. It is also a valuable source of nectar and pollen for entomofauna. The study was carried out to investigate... 相似文献
137.
Preservation of the endangered plant species requires knowledge of the impact of environmental factors on their populations. This study was undertaken to evaluate the potential of a Bayesian network (BN) model to analyze the impact of habitat conditions on the current characteristics of Pulsatilla patens (L.) Mill. population in NE Poland. The model was based on field data collected in 2011–2015 from 47 sites in the four largest forest complexes of NE Poland. The causal network between (1) the biotic and (2) abiotic factors as well as morphological-developmental features of individuals and demographic features of populations (20 attributes, 1573 records) was made using the Bayesian Search Algorithm in GeNIe 2.0. The results indicate that the greatest impact on the population features had the number of competing species in forest undergrowth and exposition of slopes. Diagnostic testing and sensitivity analysis revealed that these factors were the major variables determining the size of the population, developmental phase, and the size of individuals. Tenfold cross-validation revealed that this model was the most effective to analyze the impact of habitat conditions on the presence of generative shoots, developmental phase, and juvenile shoots. The optimal levels of factors following from the BN modeling of the impact of habitat conditions on the characteristics of the population will allow regular growth (size of individuals) and development (life cycle of individuals) of a given endangered species. 相似文献
138.
139.
Tatjana Haitina Janis Klovins Akiyoshi Takahashi Maja Löwgren Aneta Ringholm Johan Enberg Hiroshi Kawauchi Earl T Larson Robert Fredriksson Helgi B Schiöth 《BMC evolutionary biology》2007,7(1):101
Background
The melanocortin (MC) receptors have a key role in regulating body weight and pigmentation. They belong to the rhodopsin family of G protein-coupled receptors (GPCRs). The purpose of this study was to identify ancestral MC receptors in agnathan, river lamprey. 相似文献140.
Aneta M. Białkowska Ewa Gromek Joanna Krysiak Barbara Sikora Halina Kalinowska Marzena Jędrzejczak-Krzepkowska Celina Kubik Siegmund Lang Fokko Schütt Marianna Turkiewicz 《Journal of industrial microbiology & biotechnology》2015,42(12):1609-1621
2,3-Butanediol (2,3-BD) synthesis by a nonpathogenic bacterium Bacillus licheniformis NCIMB 8059 from enzymatic hydrolysate of depectinized apple pomace and its blend with glucose was studied. In shake flasks, the maximum diol concentration in fed-batch fermentations was 113 g/L (in 163 h, from the hydrolysate, feedings with glucose) while in batch processes it was around 27 g/L (in 32 h, from the hydrolysate and glucose blend). Fed-batch fermentations in the 0.75 and 30 L fermenters yielded 87.71 g/L 2,3-BD in 160 h, and 72.39 g/L 2,3-BD in 94 h, respectively (from the hydrolysate and glucose blend, feedings with glucose). The hydrolysate of apple pomace, which was for the first time used for microbial 2,3-BD production is not only a source of sugars but also essential minerals. 相似文献