全文获取类型
收费全文 | 188篇 |
免费 | 13篇 |
国内免费 | 1篇 |
出版年
2023年 | 1篇 |
2022年 | 4篇 |
2021年 | 5篇 |
2020年 | 1篇 |
2019年 | 2篇 |
2018年 | 7篇 |
2017年 | 2篇 |
2016年 | 3篇 |
2015年 | 6篇 |
2014年 | 6篇 |
2013年 | 9篇 |
2012年 | 11篇 |
2011年 | 10篇 |
2010年 | 10篇 |
2009年 | 10篇 |
2008年 | 13篇 |
2007年 | 14篇 |
2006年 | 7篇 |
2005年 | 4篇 |
2004年 | 6篇 |
2003年 | 9篇 |
2002年 | 2篇 |
2001年 | 3篇 |
2000年 | 8篇 |
1999年 | 4篇 |
1998年 | 6篇 |
1997年 | 1篇 |
1996年 | 3篇 |
1995年 | 4篇 |
1994年 | 3篇 |
1993年 | 2篇 |
1992年 | 1篇 |
1991年 | 1篇 |
1990年 | 1篇 |
1989年 | 3篇 |
1988年 | 2篇 |
1987年 | 6篇 |
1986年 | 2篇 |
1983年 | 3篇 |
1982年 | 2篇 |
1980年 | 1篇 |
1977年 | 1篇 |
1976年 | 1篇 |
1973年 | 1篇 |
1961年 | 1篇 |
排序方式: 共有202条查询结果,搜索用时 15 毫秒
1.
I. Boubriak T. Akimkina V. Polischuk A. Dmitriev S. McCready D. Grodzinsky 《Cytology and Genetics》2016,50(6):381-399
Thirty years after the Chernobyl explosion we still lack information regarding the genetic effects of radionuclide contamination on the plant population. For example, are plants adapting to the low dose of chronic ionising irradiation and showing improved resistance to radiation damage? Are they coping with changing/increased pathogenicity of fungi and viruses in the Chernobyl exclusion (ChE) zone? Are plant populations rapidly accumulating mutational load and should we expect rapid micro-evolutionary changes in plants in the Chernobyl area? This review will try to summarise the current knowledge on these aspects of plant genetics and ecology and draw conclusions on the importance of further studies in the area around Chernobyl. 相似文献
2.
Cartilage electromechanics--II. A continuum model of cartilage electrokinetics and correlation with experiments 总被引:3,自引:0,他引:3
We have formulated a continuum model for linear electrokinetic transduction in cartilage. Expressions are derived for the streaming potential and streaming current induced by oscillatory, uniaxial confined compression of the tissue, as well as the mechanical stress generated by a current density or potential difference applied to the tissue. The experimentally observed streaming potential and current-generated stress response, measured on the same specimens, are compared with the predictions of the theory over a wide frequency range. The theory compares well with the data for reasonable values of cartilage intrinsic mechanical parameters and electrokinetic coupling coefficients. Experiments also show a linear relationship between the stimulus amplitude and the transduction response amplitude, within the range of stimulus amplitudes of interest. This observation is shown to be consistent with the predictions of the linear theory. 相似文献
3.
4.
Auto?i sledovali sou?asně intensitu dýchání a intensitu fotosynthesy u list? cukrovky, neoddělených od rostliny. Několik hodin p?ed pokusem asimilovaly listy radioaktivní14CO2, na?e? byly umístěny do normální listové komory k pr? tokovému gazometrickému stanovení intensity fotosynthesy podle změny koncentrace CO2 v procházejícím vzduchu. Sou?asně s gazometrickým stanovením fotosynthesy mě?ili auto?i specifickou aktivitu kysli?níku uhli?itého ve vzduchu, který pro?el asimila?ní komorou. Podle hodnot specifické aktivity CO2, kterou vylu?uje list v temnotě, je mo?no vypo?ítat intensitu dýchání v mg CO2. Bylo zji?těno, ?e listy cukrovky vylu?ují na světle radioaktivní CO2, a to jak první tak i druhý den po asimilaci zna?eného CO2. P?i silném p?eh?ivání list? v komo?e, kdy gazometrickou metodou bylo zji?těno ji? jen dýchání, radiometricky byl stanoven výdej14CO2, odpovídající vy??í intensitě dýchaní. Auto?i vysvětlují tuto skute?nost tím, ?e i p?i p?eh?ívaní list? probíha sou?asně s dýchaním fotosyntheticka asimilace kysli?níku uhli?itého, av?ak pasivní bilance CO2 ve výměně plyn? vede ke zji?těnédýchaní, které je v podstatě rozdílem mezi intensitou piné fotosynthesy a plného dýchaní. Produkce kysli?níku uhli?itého celými listy cukrovky na světle není za normalních podmínek vý?ivy výjime?ným zjevem. 相似文献
5.
Direct sequencing of the mitochondrial displacement loop (D-loop) of shrews
(genus Sorex) for the region between the tRNA(Pro) and the conserved
sequence block-F revealed variable numbers of 79-bp tandem repeats. These
repeats were found in all 19 individuals sequenced, representing three
subspecies and one closely related species of the masked shrew group (Sorex
cinereus cinereus, S. c. miscix, S. c. acadicus, and S. haydeni) and an
outgroup, the pygmy shrew (S. hoyi). Each specimen also possessed an
adjacent 76-bp imperfect copy of the tandem repeats. One individual was
heteroplasmic for length variants consisting of five and seven copies of
the 79-bp tandem repeat. The sequence of the repeats is conducive to the
formation of secondary structure. A termination-associated sequence is
present in each of the repeats and in a unique sequence region 5' to the
tandem array as well. Mean genetic distance between the masked shrew taxa
and the pygmy shrew was calculated separately for the unique sequence
region, one of the tandem repeats, the imperfect repeat, and these three
regions combined. The unique sequence region evolved more rapidly than the
tandem repeats or the imperfect repeat. The small genetic distance between
pairs of tandem repeats within an individual is consistent with a model of
concerted evolution. Repeats are apparently duplicated and lost at a high
rate, which tends to homogenize the tandem array. The rate of D- loop
sequence divergence between the masked and pygmy shrews is estimated to be
15%-20%/Myr, the highest rate observed in D-loops of mammals. Rapid
sequence evolution in shrews may be due either to their high metabolic rate
and short generation time or to the presence of variable numbers of tandem
repeats.
相似文献
6.
7.
大鼠胼胝体内神经肽Y免疫反应阳性纤维的发育 总被引:1,自引:0,他引:1
本实验用免疫组织化学ABC法研究了大鼠胼胝体内神经肽Y免疫反应阳性(NPY-IR)纤维的生后发育。结果发现,许多NPY-IR纤维在大鼠出生时便存在于胼胝体内。NPY-IR胼胝体纤维的密度在生后1周内继续逐渐增高,在第2周内达到最高峰。之后,NPY-IR胼胝体纤维的密度逐渐下降,至第3周末时接近成年时的水平,即仅有少量NPY-IR纤维存在于胼胝体内。这些结果提示在大鼠早期生后发育过程中许多NPY-IR胼胝体纤维是暂时性的,其作用可能与大脑皮质的机能发育有关。 相似文献
8.
This paper deals with theoretical aspects of the volume changes of a system in which diffusion, convection and reaction processes are coupled. This study involves a material able to swell in the presence of a chemical effector produced by an enzyme reaction. Three limiting factors of volume change rate were considered: fluid flow, diffusion or reaction limitations. Dimensionless diffusion-reaction and diffusion-convection parameters were introduced to allow quantitative predictions in limit cases. The steady states appear to be independent of convection processes; however, the transient states depend on diffusion, convection and reaction processes. 相似文献
9.
10.
Perkovskaya G. Yu. Kravchuk Zh. N. Grodzinsky D. M. Dmitriev A. P. 《Russian Journal of Plant Physiology》2004,51(5):609-614
Metabolites of a phytopathogenic fungus Botrytis cinerea Pers. were analyzed for the presence of biotic elicitors. Three groups of elicitors competent in inducing defense responses inAllium cepa cells were identified and partly purified. The recognition of the elicitor signal in onion cells was shown to elevate the concentration of reactive oxygen species (ROS), namely, superoxide anion-radical (O2^{\overset{-}.}) and hydrogen peroxide (22). The intensity of ROS release depended on chemical identity of elicitor and its concentration. The most active ROS production in onion cells was induced by a protein fraction isolated from the medium for fungus culturing. The carbohydrate elicitors extracted from the fungus cytoplasm and cell walls of mycelia were much less effective. The dynamics of ROS generation comprised two stages. The first stage represented fast and low-amplitude changes that peaked in 15 min after the elicitor treatment. The second stage was more durable and extensive; it occurred in 1.5–6 h after the treatment. 相似文献