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1.
The effects of mispair and nonpair correction in hybrid DNA on base ratios (G + C content) and total amounts of DNA 总被引:1,自引:0,他引:1
Base ratios and total DNA amounts can vary substantially between and within
higher taxa and genera, and even within species. Gene conversion is one of
several mechanisms that could cause such changes. For base substitutions,
disparity in conversion direction is accompanied by an equivalent disparity
in base ratio at the heterozygous site. Disparity in the direction of gene
conversion at meiosis is common and can be extreme. For transitions (which
give purine [R]/pyrimidine [Y] mispairs) and for transversions giving
unlike R/R and Y/Y mispairs in hybrid DNA, this disparity could give slow
but systematic changes in G + C percentage. For transversions giving like
R/R and Y/Y mispairs, it could change AT/TA and CG/GC ratios. From the
extent of correction direction disparity, one can deduce properties of
repair enzymes, such as the ability (1) to excise preferentially the purine
from one mispair and the pyrimidine from the other for two different R/Y
mispairs from a single heterozygous site and (2) to excise one base
preferentially from unlike R/R or Y/Y mispairs. Frame-shifts usually show
strong disparity in conversion direction, with preferential cutting of the
nonlooped or the looped-out strand of the nonpair in heterozygous h-DNA.
The opposite directions of disparity for frame-shifts and their intragenic
suppressors as Ascobolus suggest that repair enzymes have a strong,
systematic bias as to which strand is cut. The conversion spectra of
mutations induced with different mutagens suggest that the nonlooped strand
is preferentially cut, so that base additions generally convert to mutant
and deletions generally convert to wild-type forms. Especially in
nonfunctional or noncoding DNA, this could cause a general increase in DNA
amounts. Conversion disparity, selection, mutation, and other processes
interact, affecting rates of change in base ratios and total DNA.
相似文献
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A comparative account of the microbiological characteristics of soils under natural forest,grassland and cropfield from Eastern India 总被引:4,自引:0,他引:4
Microbiological and physico-chemical characteristics of tropical forest, grassland and cropfield soils from India were investigated.
The study revealed that the conversion of natural forest led to a reduction of soil organic C (26–36%), total N (26–35%),
total P (33–44%), microfungal biomass (44–66%) and total microbial biomass C, N and P (25–60%) over a period of 30–50 years.
Comparative analysis of microbial activity in terms of basal soil respiration revealed maximum activity in the forest and
minimum in the cropfield soil. Analysis of microbial metabolic respiratory activity (qCO2) indicated relatively greater respiratory loss of CO2-C per unit microbial biomass in cropfield and grassland than in forest soil. Considering the importance of the microbial
component in soil, we conclude that the conversion of the tropical forest to different land uses leads to the loss of biological
stability of the soil. 相似文献
4.
B. Mittra A. B. Das R. K. Behera A. Mohammad T. K. Das P. Mohanty 《Archives Of Phytopathology And Plant Protection》2013,46(6):587-593
Abstract Fusarium induced-stress-protein (FISP) of ~51 kDa molecular mass was detected in seven day old germinated wheat (Triticum aestivum var Sonalika) seedlings infected with F. oxysporum for a period of seven days. This particular stress protein (FISP) of ~51 kDa was over-expressed in the case of Fusarium infected seedlings compared to the untreated seedlings where the presence of this protein was insignificant. Localisation of this ~51 kDa protein in root tissue by anti-CSAP (Cadmium Stress Associated Protein) antiserum showed a significantly higher number of gold particles in the case of Fusarium infected root tissue compared to the untreated control. A unique type of organised localisation of FISP around the plasma membrane and outer vacuolar membrane suggests its defensive role against Fusarium infection that might be a general stress protein against biotic and abiotic stresses. 相似文献
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Sharma RN Bhardwaj A Behera D Khanduja KL 《Indian journal of biochemistry & biophysics》2002,39(2):124-129
Superoxide anion (O2.-) and hydrogen peroxide (H2O2) production was significantly higher in blood neutrophils (PMNs) of patients with lung cancer and non-malignant lung diseases when compared to the controls (p<0.001). Superoxide dismutase (SOD) activity was significantly decreased in PMNs of patients with lung cancer (p<0.001). Similarly, catalase and glutathione peroxidase (GPx) activities were lower in PMNs of lung cancer patients as compared to non-malignant lung diseases and controls. There was an increase in HMP shunt activity as measured by rate of formation of 14CO2 from [1-14C]-glucose in PMNs of lung cancer patients. Modifications in the antioxidant defense system in PMNs of malignant and nonmalignant lung diseases, the changes being more in the malignancy are indicated. 相似文献
8.
Entry of bovine viral diarrhea virus into ovine cells occurs through clathrin-dependent endocytosis and low pH-dependent fusion 总被引:1,自引:0,他引:1
Basavaraj Shrishail Mathapati Niranjan Mishra Katherukamem Rajukumar Ram Kumar Nema Sthita Pragnya Behera Shiv Chandra Dubey 《In vitro cellular & developmental biology. Animal》2010,46(5):403-407
Although mechanisms of bovine viral diarrhea virus (BVDV) entry into bovine cells have been elucidated, little is known concerning
pestivirus entry and receptor usage in ovine cells. In this study, we determined the entry mechanisms of BVDV-1 and BVDV-2
in sheep fetal thymus cells. Both BVDV-1 and BVDV-2 infections were inhibited completely by chlorpromazine, β-methyl cyclodextrin,
sucrose, bafilomycin A1, chloroquine, and ammonium chloride. Simultaneous presence of reducing agent and low pH resulted in
marked loss of BVDV infectivity. Moreover, BVDV was unable to fuse with ovine cell membrane by the presence of reducing agent
or low pH alone, while combination of both led to fusion at low efficiency. Furthermore, sheep fetal thymus cells acutely
infected with BVDV-1 or BVDV-2 were found protected from heterologous BVDV infection. Taken together, our results showed for
the first time that entry of both BVDV-1 and BVDV-2 into ovine cells occurred through clathrin-dependent endocytosis, endosomal
acidification, and low pH-dependent fusion following an activation step, besides suggesting the involvement of a common ovine
cellular receptor during attachment and entry. 相似文献
9.
Mahula (Madhuca latifolia L.) is a deciduous tree commonly found in the tropical rain forests of Asian and Australian continent. Corolla, the edible
part of its flowers, is rich in fermentable sugar (37 ± 0.23%; on dry weight basis). Batch fermentation of mahula flowers
was carried out using Zymomonas mobilis MTCC 92 free cells and cells immobilized in calcium alginate matrix. The ethanol productions were 122.9 ± 0.972 and 134.6
± 0.104 g/kg flowers on dry weight basis using free and immobilized cells, respectively, after 96 h of fermentation, which
showed that cells entrapped in calcium alginate matrix yielded 8.7% more ethanol than free cells. Further, the immobilized
cells were physiologically active up to three more cycles of fermentation producing 132.7 ± 0.095, 130.5 ± 0.09 and 128.7
± 0.056 g ethanol per kg flower in first, second and third cycle, respectively. 相似文献
10.
Electrochemistry of microperoxidase-11 (MPx-11) anchored on the mixed self-assembled monolayer (SAM) of 2-(2-mercaptoethylpyrazine) (PET) and 4,4'-dithiodibutyric acid (DTB) on gold (Au) electrode and the biosensing of uric acid (UA) is described. MPx-11 has been covalently anchored on the mixed SAM of PET and DTB on Au electrode. MPx-11 on the mixed self-assembly exhibits reversible redox response characteristic of a surface confined species. The heterocyclic ring of PET promotes the electron transfer between the electrode and the redox protein. The apparent standard rate constant kapps obtained for the redox reaction of MPx-11 on the mixed monolayer is approximately 2.15 times higher than that on the single monolayer of DTB modified electrode. MPx-11 efficiently mediates the electrocatalytic reduction of H2O2. MPx-11 electrode is highly sensitive to H2O2 and it shows linear response for a wide concentration range. The electrocatalytic activity of the MPx-11 electrode is combined with the enzymatic activity of uricase (UOx) to fabricate uric acid biosensor. The bienzyme assembly is highly sensitive towards UA and it could detect UA as low as 2 microM at the potential of -0.1 V. The biosensor shows linear response with a sensitivity of 3.4+/-0.08 nA cm(-2) microM(-1). Ascorbate (AA) and paracetamol (PA) do not significantly interfere in the amperometric sensing of UA. 相似文献