全文获取类型
收费全文 | 236篇 |
免费 | 25篇 |
出版年
2022年 | 1篇 |
2021年 | 2篇 |
2020年 | 3篇 |
2019年 | 6篇 |
2018年 | 8篇 |
2017年 | 1篇 |
2016年 | 15篇 |
2015年 | 14篇 |
2014年 | 11篇 |
2013年 | 19篇 |
2012年 | 11篇 |
2011年 | 13篇 |
2010年 | 8篇 |
2009年 | 10篇 |
2008年 | 8篇 |
2007年 | 12篇 |
2006年 | 11篇 |
2005年 | 9篇 |
2004年 | 10篇 |
2003年 | 8篇 |
2002年 | 7篇 |
2001年 | 3篇 |
2000年 | 6篇 |
1999年 | 4篇 |
1998年 | 2篇 |
1997年 | 2篇 |
1996年 | 3篇 |
1995年 | 1篇 |
1993年 | 2篇 |
1992年 | 3篇 |
1991年 | 8篇 |
1990年 | 5篇 |
1989年 | 1篇 |
1988年 | 3篇 |
1986年 | 4篇 |
1985年 | 2篇 |
1984年 | 1篇 |
1982年 | 3篇 |
1981年 | 3篇 |
1980年 | 6篇 |
1979年 | 1篇 |
1977年 | 1篇 |
1975年 | 1篇 |
1973年 | 1篇 |
1969年 | 1篇 |
1968年 | 1篇 |
1967年 | 2篇 |
1966年 | 1篇 |
1965年 | 2篇 |
1865年 | 1篇 |
排序方式: 共有261条查询结果,搜索用时 15 毫秒
1.
B. Nicolaus A. Trincone L. Lama I. Romano F. Marsiglia A. Gambacorta 《Biotechnology letters》1991,13(9):667-670
Summary An economic method to grow the thermoacidophilic archaebacteriumSulfolobus solfataricus is reported. 相似文献
2.
W. Junger H. J. Dahmen 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》1991,169(5):641-646
Waterstriders (Gerris paludum) often try to maintain a nearly stationary position on a moving water surface. Passive motion is restricted to 3 degrees of freedom: yaw, longitudinal, and transverse displacement. They correct for passive rotation and translation by distinct behavioral sequences. The compensatory behavior is predominantly visually controlled.
The restriction of degreess of freedom reduces the complexity of the motion-induced visual flow field. Each motion component induces its own flow field component. We propose that those areas of the visual field are preferred for analysis where the directions of the 3 flow field components differ most. These areas (Figs. 2 and 3) have their largest extent at 45° above the horizon. 相似文献
1. | When waterstriders are rotated and translated simultaneously, they are able to discriminate their own rotation and translation visually. |
2. | They discriminate their rotation from their translation even if the visible pattern is restricted to a monocular visual field. |
3. | They detect rotation only if they see an extended pattern. |
3.
Summary Cryosubstitution provides an improved ultrastructural preservation of the two plant pathogensVenturia inaequalis andErysiphe graminis when compared to conventional preparation methods. Further, freezing the infected whole leaf material on a copper block cooled with liquid helium gave better results than those observed with the propane plunging method. Novel observations concerning the fungal stroma and haustoria were made which showed ribosomes organized into groups that were evenly distributed throughout the cytoplasm of both fungi. Stretches of rough endoplasmic reticulum were present, and microtubules were seen, sometimes associated with mitochondria. A large number of darkly staining vacuoles were observed in both fungi. The polarity of organelles and microtubules along the longitudinal axis of the haustorial body ofE. gramnis and along the growing direction of subcuticular stroma and runner hypha ofV. inaequalis was evident. InE. graminis filasomes were observed, as were Golgi-like bodies. These new observations, together with the advantages of the cryosubstitution technique, can serve as a basis for further studies in understanding host-parasite interactions. 相似文献
4.
5.
“Bacillus thermoantarcticus” sp. nov., from Mount Melbourne,Antarctica: a novel thermophilic species
B. Nicolaus Licia Lama Enrico Esposito Maria Cristina Manca Guido di Prisco Agata Gambacorta 《Polar Biology》1996,16(2):101-104
A novel thermophilic Gram-positive bacillus, “Bacillus thermoantarcticus”, isolated from geothermal soil near the crater of Mount Melbourne, is described. The organism grows at an optimal temperature
of 63°C at pH 6.0, is oxidase-positive, catalase-negative and produces an exopolysaccharide, an exocellular xylanase, an intracellular
alcohol dehydrogenase and exo- and endocellular α-glucosidase(s). The sequence of 16S rDNA is very similar to that of “Bacillus thermoglucosidasius”; however, the guanine-plus-cytosine (G+C) content is 8 mol% higher. The type strain is “Bacillus thermoantarcticus” (DSM 9572).
Received : 3 February 1995/Accepted : 12 May 1995 相似文献
6.
Uptake kinetics of iron-phytosiderophores in two maize genotypes differing in iron efficiency 总被引:5,自引:0,他引:5
Iron inefficiency in the maize ( Zea mays L.) mutant ysl is caused by a defect in the uptake system for Fe-phytosiderophores. To characterize this defect further, the uptake kinetics of Fe-phytosiderophores in ysl was compared to the Fe-efficient maize cultivar Alice. Short-term uptake of 59 Fe-labeled Fe-deoxymugineic acid (Fe-DMA) was measured over a concentration range of 0.03 to 300 μM. Iron uptake in Fe-deficient plants followed Michaelis-Menten kinetics up to about 30 μM and was linear at higher concentrations, indicating two kinetically distinct components in the uptake of Fe-phytosiderophores. The saturable component had similar Km (∼ 10 μM) in both genotypes. In contrast. Vmax was 5.5 μmol Fe-DMA g−1 dry weight [30 min]−1 in Alice, but only 0.6 μmol Fe-DMA g−1 dry weight [30 min]−1 in ysl . Uptake experiments with double-labeled 59 Fe-[14 C]DMA suggest that in both cultivars Fe-DMA was taken up by the roots as the intact chelate. The results indicate the existence of a high-affinity and a low-affinity uptake system mediating Fe-phytosiderophore transport across the root plasma membrane in maize. Apparently, the mutation responsible for Fe inefficiency in ysl affected high-affected uptake and led to a decrease in activity and/or number of Fe-phytosiderophore transporters. 相似文献
7.
H. -J. Dahmen 《Biological cybernetics》1977,26(1):17-23
The menotactic orientation of the prosobranch mollusc Littorina littorea to a one stripe pattern (Fig. 2) has been investigated under open-loop and closed-loop conditions. Results: 1) Under open-loop conditions the animals try to compensate for an angular deviation of the pattern from the menotactic angular position by turning movements of, on the average, constant angular velocity (Fig. 4). 2) The angular velocity
depends on this deviation according to the
-characteristic (Fig. 5). The orientation behaviour under closed-loop conditions can be directly derived from the
-characteristic. Within experimental limits the snail does not show an optomotor response. 3) To patterns of wedge-shaped intensity distribution the snails orientate at a small angle relative to the edge of the pattern (Fig. 3). The orientation angle of the animals to this pattern is much less variable than the orientation angle to a single light source. The orientation behaviour shows that the intensity gradient of the pattern is important for the orientation of the animal. 4) A normally distributed noise process is superimposed on the average orientation direction. The variance of this noise process is the same for the orientation under open-loop and under closed-loop conditions (Fig. 7). In both cases the power spectrum of the noise process contains pronounced maxima at equally spaced frequencies (Fig. 8). 相似文献
8.
Trincone A Lama L Lanzotti V Nicolaus B De Rosa M Rossi M Gambacorta A 《Biotechnology and bioengineering》1990,35(6):559-564
The method of resting cells has been of interest in the development of biocatalysts applied to organic reactions.This article deals with the use of resting cells of a thermophilic archaebacterium Sulfolobus solfataricus, in the asymmetric reduction of acyclic, cyclic, and aromatic ketones. The system allows the continuous regeneration of endogenous coenzyme with the coupled substrate approach. The results indicate that the direction of hydride attack was equatorial on the re face of the carbonyl group of substrates producing (S)-alcohols with a good optical yield. A convenient system for the reuse of resting cells has been set out to synthesize (S)-alcohols on a preparative scale. 相似文献
9.
P Cammarano A Teichner G Chinali P Londei M de Rosa A Gambacorta B Nicolaus 《FEBS letters》1982,148(2):255-259
A spermine-dependent, polyphenylalanine-synthesizing cell-free system having an optimum activity at 75-85 degrees C, has been developed from the extremely thermoacidophilic archaebacterium Caldariella acidophila. The C. acidophila system is totally insensitive to the EF-Tu targeted antibiotics pulvomycin (at 40 degrees C) and kirromycin (at 47-72 degrees C) contrary to control systems derived from both mesophilic (Escherichia coli) and thermoacidophilic (Bacillus acidocaldarius) eubacteria. The archaebacterial EF-Tu-equivalent factor is also immunologically unrelated to eubacterial EF-Tu and does not cross react with antibodies against Escherichia coli EF-Tu. The pulvomycin and kirromycin reactions thus provide new phyletic markers for archaebacterial ancestry. 相似文献
10.
Mario De Rosa Agata Gambacorta Barbara Nicolaus Salvatore Sodano J.D. BuLock 《Phytochemistry》1980,19(5):833-836
Individual di(biphytanyl) diglycerol tetraether lipids from thermoacidophile archaebacteria of the Caldariella series, with differently cyclized biphytanyl components, are separated and shown to have structures 8–12, with the glycerol and biphytanyl components demonstrably both antiparallel and with partial assignments of stereochemistry. Tetraethers with alternative arrangements of the components are absent. The structures allow previous observations on these and related lipids to be rationalized both biosynthetically and phyletically. 相似文献