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排序方式: 共有96条查询结果,搜索用时 31 毫秒
1.
A L Rakhmilevich T L Migdal M S Rakhimova M A Shne?derova V Ia Chirva A E Zemliakov 《Antibiotiki i khimioterapii͡a》1989,34(11):836-839
Production of tumor necrosis factor (TNF) and interleukin-1 (IL-1) by macrophages of the spleen and peritoneal exudate of mice as well as cytotoxic factors (CFs) by murine splenocytes after in vitro activation was estimated. All the derivatives of muramyldipeptide (MDP) and glucosaminylmuramyldipeptide (GMDP) were able to induce production of TNF and CFs. In the presence of lipopolysaccharide (LPS), the effect was always higher. The response of the spleen macrophages to the effect of the preparations was higher than that of the peritoneal ones and ++non-fractionated splenocytes. GMDP and GMDP4 especially in the presence of LPS had the highest effect on induction of IL-1 by the murine peritoneal macrophages. On the contrary, MDP induced higher IL-1 synthesis by the spleen macrophages. The most active substances with respect to production of TNF, CFs and IL-1, i.e. MDP3 and GMDP4, might be recommended for immunotherapy of syngeneic tumors in animals. 相似文献
2.
R N Rakhimov N N Rakhimova P Iu Khakman A V Riandur 《Biulleten' eksperimental'no? biologii i meditsiny》1989,107(6):676-678
The content of free amino acid pool in symmetric regions of cortex, hypothalamus, midbrain and blood of rats which had produced the movement conditioned reflex strengthened by feeding was studied. It was established that the "untrained" rats have higher content of free amino acid pool in their blood. The brain of the experimental animals revealed the biochemical asymmetry which was marked by the differences in free amino acid pool distribution between the left and right halves of the studied regions of brain. It was shown that left sided asymmetry animals i.e. animals with heightened content of free amino acid pool in the left half of the brain dominated in the "untrained" group of rats. The supposition was expressed that this biochemical asymmetry may contribute to the ability of animals to learn. 相似文献
3.
S. M. Zyryanov A. S. Kovalev D. V. Lopaev E. M. Malykhin A. T. Rakhimov T. V. Rakhimova K. N. Koshelev V. M. Krivtsun 《Plasma Physics Reports》2011,37(10):881-889
Low-pressure hydrogen is an important component of the working medium in extreme ultraviolet (EUV) projection lithography.
Under the action of EUV photons and fast secondary electrons on the gas medium, plasma and atomic hydrogen, actively interacting
with the surface, are produced. This interaction is very important, because it largely determines the lifetime of the multilayered
EUV optics. In this study, the loss of atomic hydrogen under the conditions of a low pressure (<10 Torr) RF plasma discharge
on the surfaces of materials used in EUV lithography is investigated. The surface loss probabilities of H atoms on these materials
are measured. It is shown that surface recombination of atomic hydrogen goes according to the Eley-Rideal mechanism via direct
recombination of H atoms from the gas phase with chemically and physically adsorbed atoms. In this case, the surface recombination
probability is mainly determined by the density of chemical adsorption sites. The density of adsorption sites and the desorption
energy of H atoms are estimated. The desorption energy of physically adsorbed H atoms on pure metal surfaces (or surfaces
exposed to plasma) is about 0.5 eV, and the density of sorption sites is close to the surface density of atoms. This results
in a high loss probability of H atoms on metals (∼0.1). Therefore, to provide efficient transportation of hydrogen atoms,
it is necessary to use materials with the lowest loss probability of H atoms, i.e., dielectrics. 相似文献
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1. The increase of species richness with the area of the habitat sampled, that is the species–area relationship, and its temporal analogue, the species–time relationship (STR), are among the few general laws in ecology with strong conservation implications. However, these two scale‐dependent phenomena have rarely been considered together in biodiversity assessment, especially in freshwater systems. 2. We examined how the spatial scale of sampling influences STRs for a Central‐European stream fish assemblage (second‐order Bernecei stream, Hungary) using field survey data in two simulation‐based experiments. 3. In experiment one, we examined how increasing the number of channel units, such as riffles and pools (13 altogether), and the number of field surveys involved in the analyses (12 sampling occasions during 3 years), influence species richness. Complete nested curves were constructed to quantify how many species one observes in the community on average for a given number of sampling occasions at a given spatial scale. 4. In experiment two, we examined STRs for the Bernecei fish assemblage from a landscape perspective. Here, we evaluated a 10‐year reach level data set (2000–09) for the Bernecei stream and its recipient watercourse (third‐order Kemence stream) to complement results on experiment one and to explore the mechanisms behind the observed patterns in more detail. 5. Experiment one indicated the strong influence of the spatial scale of sampling on the accumulation of species richness, although time clearly had an additional effect. The simulation methodology advocated here helped to estimate the number of species in a diverse combination of spatial and temporal scale and, therefore, to determine how different scale combinations influence sampling sufficiency. 6. Experiment two revealed differences in STRs between the upstream (Bernecei) and downstream (Kemence) sites, with steeper curves for the downstream site. Equations of STR curves were within the range observed in other studies, predominantly from terrestrial systems. Assemblage composition data suggested that extinction–colonisation dynamics of rare, non‐resident (i.e. satellite) species influenced patterns in STRs. 7. Our results highlight that the determination of species richness can benefit from the joint consideration of spatial and temporal scales in biodiversity inventory surveys. Additionally, we reveal how our randomisation‐based methodology may help to quantify the scale dependency of diversity components (α, β, γ) in both space and time, which have critical importance in the applied context. 相似文献
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8.
A. A. Chukalovsky T. V. Rakhimova K. S. Klopovsky Yu. A. Mankelevich O. V. Proshina 《Plasma Physics Reports》2011,37(3):251-262
The kinetic processes occurring in an electric-discharge oxygen-iodine laser are analyzed with the help of a 2D (r, z) gasdynamic model taking into account transport of excited oxygen, singlet oxygen, and radicals from the electric discharge
and their mixing with the iodine-containing gas. The main processes affecting the dynamics of the gas temperature and gain
are revealed. The simulation results obtained using the 2D model agree well with the experimental data on the mixture gain.
A subsonic oxygen-iodine laser in which singlet oxygen is generated by a 350 W transverse RF discharge excited in an oxygen
flow at a pressure P = 10 Torr and the discharge tube wall is covered with mercury oxide is simulated. The simulated mixing system is optimized
in terms of the flow rate and the degree of preliminary dissociation of the iodine flow. The optimal regime of continuous
operation of a subsonic electric-discharge oxygen-iodine laser is found. 相似文献
9.
A. N. Vasil’eva K. S. Klopovskii A. S. Kovalev D. V. Lopaev Yu. A. Mankelevich N. A. Popov A. T. Rakhimov T. V. Rakhimova 《Plasma Physics Reports》2005,31(4):325-337
The production of O2(a1Δg) singlet oxygen in non-self-sustained discharges in pure oxygen and mixtures of oxygen with noble gases (Ar or He) was studied experimentally. It is shown that the energy efficiency of O2(a1Δg production can be optimized with respect to the reduced electric field E/N. It is shown that the optimal E/N values correspond to electron temperatures of 1.2–1.4 eV. At these E/N values, a decrease in the oxygen percentage in the mixture leads to an increase in the excitation rate of singlet oxygen because of the increase in the specific energy deposition per O2 molecule. The onset of discharge instabilities not only greatly reduces the energy efficiency of singlet oxygen production but also makes it impossible to achieve high energy deposition in a non-self-sustained discharge. A model of a non-self-sustained discharge in pure oxygen is developed. It is shown that good agreement between the experimental and computed results for a discharge in oxygen over a wide range of reduced electric fields can be achieved only by taking into account the ion component of the discharge current. The cross section for the electron-impact excitation of O2(a1Δg and the kinetic scheme of the discharge processes with the participation of singlet oxygen are verified by comparing the experimental and computed data on the energy efficiency of the production of O2(a1Δg and the dynamics of its concentration. It is shown that, in the dynamics of O2(a1Δg molecules in the discharge afterglow, an important role is played by their deexcitation in a three-body reaction with the participation of O(3P) atoms. At high energy depositions in a non-self-sustained discharge, this reaction can reduce the maximal attainable concentration of singlet oxygen. The effect of a hydrogen additive to an Ar: O2 mixture is analyzed based on the results obtained using the model developed. It is shown that, for actual electron beam current densities, a significant energy deposition in a non-self-sustained discharge in the mixtures under study can be achieved due to the high rate of electron detachment from negative ions. In this case, however, significant heating of the mixture can lead to a rapid quenching of O2(a1Δg molecules by atomic hydrogen. 相似文献
10.
A study was made of changes in the rates of respiration, heat production, and membrane characteristics in cells of excised roots of wheat seedlings under the modulation of plasma membrane ion permeability by two membrane active compounds: valinomycin (20 microM (V50)) and chlorpromazine (50 microM (CP50) and 100 microM (CP100)). Both compounds increased the loss of potassium ions, which correlated with the lowering of membrane potential, rate of respiration, and heat production after a 2 h exposure. The differences in alteration of these parameters were due to specific action of either compound on the membrane and to the extent of ion homeostasis disturbance. V20 had a weak effect on the studied parameters. V50 caused an increase of the rate of respiration and heat production, which enhanced following a prolonged action (5 h) and were associated with ion homeostatis restoration. The extent of alteration of membrane characteristics (an increase of potassium loss by roots, and lowering of cell membrane potential) as well as energy expense under the action of CP50 during the first period were more pronounced than in the presence of V50. During a prolonged action of CP50, the increase of respiration intensity and heat production correlated with partial recovery of ion homeostatis in cells. Essential lowering of membrane potential and substantial loss of potassium by cells, starting from the early stages of their response reaction, were followed by inhibition of respiration rate and heat production. Alterations of the structure and functional characteristics of excised root cells indicate the intensification of the membrane-tropic effect of a prolonged action of CP100, and the lack of cell energy resources. 相似文献