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51.
Ismail Mansouri Wafae Squalli Aymen Nefla Mohamed Mounir Hamid Achiban Chedad Abdelwahab Mohammed Hmidani Lahsen El Ghadraoui Mohamed Dakki 《African Journal of Ecology》2023,61(1):153-162
The identification of migration dates and wintering zones for migratory birds are key elements for the understanding of the Afro-Palearctic migration system. From 2015 to 2022, a large-scale survey of Turtle Doves Streptopelia turtur, a vulnerable species, was established in Northwest Africa, including Morocco, Algeria, and Tunisia. We monitored migration dates and wintering individuals using the line-transect method. We found that Turtle Doves arrived in the last week of March and left the North African region in mid-October. Compared with Morocco, Doves arrived significantly earlier in Algeria and Tunisia. Moreover, Doves were discovered wintering on nine Northwest African sites, from October to February, where individuals feed in groups. We found that the occurrence probability of wintering Turtle Doves decreased significantly with increasing temperature and rainfall. Birds wintered most often close to wetlands since the overwintering probability decreased with the increasing distance from the recording area to the nearest water body. These are the first and only detailed findings on the migration phenology of the globally vulnerable Turtle Dove in north western Africa. 相似文献
52.
Messaoudi S Kergourlay G Rossero A Ferchichi M Prévost H Drider D Manai M Dousset X 《International microbiology》2011,14(2):103-110
Bacteriocins produced by Lactobacillus salivarius have been recently recognized as a natural means to control Campylobacter and Salmonella in live poultry. This finding is of relevance since Campylobacter jejuni and Campylobacter coli are the predominant species isolated from poultry that are associated with human campylobacteriosis. In the present work, lactic acid bacteria (LAB) isolated from the cecum of twenty Tunisian chickens were identified and those isolates with antagonism against Campylobacter were further characterized. Following their preliminary confirmation as LAB, 150 strains were identified by combining morphological criteria, biochemical tests, and molecular methods, the latter inluding intergenic 16S- 23S PCR, specific lactobacilli PCR, and a biphasic approach. Most of the LAB isolated belonged to the genus Lactobacillus, among them Lb. sakei (33.3%), Lb. salivarius (19.4%), Lb. reuteri (8.6%), and Lb. curvatus (8.6%). The other LAB strains included those of the genus Weissella (16.7%), Enterococcus faecalis (5.3%), Leuconostoc mesenteroides (2.7%), Lactococcus graviae (2.7%), and Streptococcus sp. (2.7%). The Lactobacilli strains were tested for their antagonism against C. jejuni and C. coli. The activity of three of them, Lb. salivarius SMXD51, Lb. salivarius MMS122, and Lb. salivarius MMS151, against the aforementioned target strains could be ascribed to the production of bacteriocins. 相似文献
53.
54.
Molecular Dynamics Simulations of Lipid Membrane Electroporation 总被引:1,自引:0,他引:1
The permeability of cell membranes can be transiently increased following the application of external electric fields. Theoretical approaches such as molecular modeling provide a significant insight into the processes affecting, at the molecular level, the integrity of lipid cell membranes when these are subject to voltage gradients under similar conditions as those used in experiments. This article reports on the progress made so far using such simulations to model membrane—lipid bilayer—electroporation. We first describe the methods devised to perform in silico experiments of membranes subject to nanosecond, megavolt-per-meter pulsed electric fields and of membranes subject to charge imbalance, mimicking therefore the application of low-voltage, long-duration pulses. We show then that, at the molecular level, the two types of pulses produce similar effects: provided the TM voltage these pulses create are higher than a certain threshold, hydrophilic pores stabilized by the membrane lipid headgroups form within the nanosecond time scale across the lipid core. Similarly, when the pulses are switched off, the pores collapse (close) within similar time scales. It is shown that for similar TM voltages applied, both methods induce similar electric field distributions within the membrane core. The cascade of events following the application of the pulses, and taking place at the membrane, is a direct consequence of such an electric field distribution. 相似文献
55.
Halappanavar SS Rhun YL Mounir S Martins LM Huot J Earnshaw WC Shah GM 《The Journal of biological chemistry》1999,274(52):37097-37104
To determine whether caspase-3-induced cleavage of poly(ADP-ribose) polymerase (PARP), a DNA damage-sensitive enzyme, alters the balance between survival and death of the cells following DNA damage, we created stable cell lines that express either caspase-uncleavable mutant or wild type PARP in the background of PARP (-/-) fibroblasts. The survival and apoptotic responses of these cells were compared after exposure to N-methyl-N'-nitro-N-nitrosoguanidine (MNNG), a DNA-damaging agent that activates PARP, or to tumor necrosis factor-alpha, which causes apoptosis without initial DNA damage. In response to MNNG, the cells with caspase-uncleavable PARP were very resistant to loss of viability or induction of apoptosis. Most significantly, approximately 25% of these cells survived and retained clonogenicity at a level of DNA damage that eliminated the cells with wild type PARP or PARP (-/-) cells. Expression of caspase-uncleavable PARP could not protect the cells from death induced by tumor necrosis factor, although there was a slower progression of apoptotic events in these cells. Therefore, one of the functions for cleavage of PARP during apoptosis induced by alkylating agents is to prevent survival of the extensively damaged cells. 相似文献
56.
Nejla Soudani Moez Rafrafi Ibtissem Ben Amara Ahmed Hakim Afef Troudi Khaled Mounir Zeghal Hichem Ben Salah Tahia Boudawara Najiba Zeghal 《Journal of physiology and biochemistry》2013,69(2):239-253
Chromium(VI), a very strong oxidant, causes high cytotoxicity through oxidative stress in tissue systems. Our study investigated the potential ability of ethanolic Citrus aurantium L., family Rutaceae extract, used as a nutritional supplement, to alleviate lung oxidative damage induced by Cr(VI). A high-performance liquid chromatography coupled with a mass spectrometer method was developed to separate and identify flavonoids in C. aurantium L. Six flavonoids were identified, as (1) poncirin, (2) naringin, (3) naringenin, (4) quercetin, (5) isosinensetin, and (6) tetramethyl-o-isoscutellarein. Adult Wistar rats, used in this study, were divided into six groups of six animals each: group I served as controls which received standard diet, group II received via drinking water K2Cr2O7 alone (700 ppm), groups III and IV were pretreated for 10 days with ethanol extract of C. aurantium L. at doses of 100 and 300 mg/kg body weight/day, respectively, and then K2Cr2O7 was administrated during 3 weeks, and groups V and VI received during 10 days only C. aurantium L. ethanol extract at doses of 100 and 300 mg/kg/day, respectively. Ethanol extract of C. aurantium L. was administered orally. Rats exposed to Cr(VI) showed in lung an increase in malondialdehyde and protein carbonyl levels and a decrease in sulflydryl content, glutathione, nonprotein thiol, and vitamins C and E levels. Decreases in enzyme activities such as in Na+K+ ATPase, catalase, glutathione peroxidase, and superoxide dismutase were noted. Pretreatment with C. aurantium L. of chromium-treated rats ameliorated all biochemical parameters. Lung histological studies confirmed the biochemical parameters and the beneficial role of C. aurantium L. 相似文献
57.
Thirteen Cuvier’s gazelles were relocated to a 6-ha acclimatization enclosure in Boukornine National Park (Boukornine NP)
in Tunisia, where they are part of a reintroduction project. To determine the degree of adaptation and habitat use under the
new conditions, the acclimatization enclosure was divided into 6 sections according to topography, plant cover and plant species
in the area. Signs of gazelle activity were coded as feeding site, paths, passages, feces and resting places. Sampling was
done in spring, summer and autumn from September 2000 to July 2001. Multivariate analysis using PATN analysis and Χ2 distribution tests were used to analyze the data. Multivariate analysis yielded 5 groups of biotopes according to the above
variables. The Χ2 distribution test showed the significant effect of each variable on the presence of signs of gazelles. Cuvier’s gazelles
prefer areas with low and west to north facing slopes and scant plant cover; animals are attracted to the proximity of the
fence as the limit of their territory and even though the presence of humans does not represent a disturbance, gazelles select
areas far (> 50 m) from the supplementary feeding and water supply for their activities. 相似文献
58.
Traïkia M Warschawski DE Recouvreur M Cartaud J Devaux PF 《European biophysics journal : EBJ》2000,29(3):184-195
It has been reported that repetitive freeze-thaw cycles of aqueous suspensions of dioleoylphosphatidylcholine form vesicles
with a diameter smaller than 200 nm. We have applied the same treatment to a series of phospholipid suspensions with particular
emphasis on dioleoylphosphatidylcholine/dioleoylphosphatidic acid (DOPC/DOPA) mixtures. Freeze-fracture electron microscopy
revealed that these unsaturated lipids form unilamellar vesicles after 10 cycles of freeze-thawing. Both electron microscopy
and broad-band 31P NMR spectra indicated a disparity of the vesicle sizes with a highest frequency for small unilamellar vesicles (diameters
≤30 nm) and a population of larger vesicles with a frequency decreasing exponentially as the diameter increases. From 31P NMR investigations we inferred that the average diameter of DOPC/DOPA vesicles calculated on the basis of an exponential
size distribution was of the order of 100 nm after 10 freeze-thaw cycles and only 60 nm after 50 cycles. Fragmentation by
repeated freeze-thawing does not have the same efficiency for all lipid mixtures. As found already by others, fragmentation
into small vesicles requires the presence of salt and does not take place in pure water. Repetitive freeze-thawing is also
efficient to fragment large unilamellar vesicles obtained by filtration. If applied to sonicated DOPC vesicles, freeze-thawing
treatment causes fusion of sonicated unilamellar vesicles into larger vesicles only in pure water. These experiments show
the usefulness of NMR as a complementary technique to electron microscopy for size determination of lipid vesicles. The applicability
of the freeze-thaw technique to different lipid mixtures confirms that this procedure is a simple way to obtain unilamellar
vesicles.
Received: 2 September 1999 / Revised version: 27 February 2000 / Accepted: 27 February 2000 相似文献
59.
60.
Mouna Kallel Fatma Elloumi Abdelmajid Khabir Lilia Ghorbal Souhir Chaabouni Habib Amouri Mounir Frikha Jamel Daoud 《Reports of Practical Oncology and Radiotherapy》2015,20(3):155-160