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41.
Changes in the activity of catalase (Cat) and in the levels of H2O2 were followed throughout dormancy in buds of grapevines (Vitis vinifera L.). In grapevines grown in the Elqui valley in Chile, a region with warm-winters, the activity of Cat increased during the recess period of buds, reaching a maximum and thereafter decreased to less than one third of its maximal activity. Three isoforms of Cat were detected in extracts of buds by native PAGE analysis, and the extracted activity was inhibited competitively by hydrogen cyanamide (HC), a potent bud-break agent. Furthermore, HC applications to field-grown grapevines in addition to the expected effect on advancing bud break, reduced the Cat activity during bud dormancy. Similar reductions were observed during dormancy in buds of grapevines grown in the Central valley in Chile, a region with temperate winters, suggesting that HC and winter chilling inhibits the activity of the main H2O2 degrading enzyme in grape buds. A transient rise in H2O2 levels preceded the release of buds from endodormancy, moreover, the peak of H2O2 and the onset of bud break occurred earlier in HC treated than in control grapevines, suggesting the participation of H2O2 as a signal molecule in the release of endodormancy in grape buds. The relationship between Cat inhibition, rise in H2O2 levels and initiation of bud break are discussed. 相似文献
42.
The purpose of this research was to evaluate the influence of dry granulation parameters on granule and tablet properties
of spray-dried extract (SDE) fromMaytenus ilicifolia, which is widely used in Brazil in the treatment of gastric disorders. The compressional behavior of the SDE and granules
of the SDE was characterized by Heckel plots. The tablet properties of powders, granules, and formulations containing a high
extract dose were compared. The SDE was blended with 2% magnesium stearate and 1% colloidal silicon dioxide and compacted
to produce granules after slugging or roll compaction. The influences of the granulation process and the roll compaction force
on the technological properties of the granules were studied. The flowability and density of spray-dried particles were improved
after granulation. Tablets produced by direct compression of granules showed lower crushing strength than the ones obtained
from nongranulated material. The compressional analysis by Heckel plots revealed that the SDE undergoes plastic deformation
with a very low tendency to rearrangement at an early stage of compression. On the other hand, the granules showed an intensive
rearrangement as a consequence of fragmentation and rebounding. However, when the compaction pressure was increased, the granules
showed plastic deformation. The mean yield pressure values showed that both granulation techniques and the roll compaction
force were able to reduce the material's ability to undergo plastic deformation. Finally, the tablet containing a high dose
of granules showed a close dependence between crushing strength and the densification degree of the granules (ie, roll compaction
force).
Published: October 14, 2005 相似文献
43.
Cholesteryl ester transfer protein variants have differential stability but uniform inhibition by torcetrapib 总被引:2,自引:0,他引:2
Lloyd DB Lira ME Wood LS Durham LK Freeman TB Preston GM Qiu X Sugarman E Bonnette P Lanzetti A Milos PM Thompson JF 《The Journal of biological chemistry》2005,280(15):14918-14922
44.
45.
Miguel Jiménez-Valdés Héctor Godínez-Alvarez Javier Caballero Rafael Lira 《Economic botany》2010,64(2):149-160
Population Dynamics of
Agave marmorata
Roezl. under Two Contrasting Management Systems in Central Mexico. This paper evaluates the impacts of traditional management on the population dynamics of Agave marmorata, a multipurpose, useful species that is dominant in the Zapotitlán Salinas Valley, Puebla, Mexico. During 2002–2003 and 2003–2004,
we constructed matrix models for two populations—one unmanaged, the other subject to plant extraction and cutting of flowering
stalks. We also conducted prospective (elasticity) and retrospective (life table response experiments) analyses. Overall,
the unmanaged population had higher finite rates of increase (λ) than the managed one. This variation in λ was the result
of a decrease in the individual growth and fecundity in the managed population. Survival and growth were the demographic processes
with the highest contribution to λ in the unmanaged population, while survival was the most important in the managed one.
Our results suggest that management and plant extraction practices could be having negative effects on the population dynamics
of this plant species. Recommendations are provided in order to promote positive effects on its vital rates and regeneration
capacity. 相似文献
46.
Cruz Aldán E Lira Torres I Güiris Andrade DM Osorio Sarabia D Quintero M MT 《Revista de biología tropical》2006,54(2):445-450
We analyzed 19 samples of Baird's tapir feces from La Sepultura Biosphere Reserve, collected between March and July 1999. We also took samples directly from a male tapir captured at the Montes Azules Biosphere Reserve. Both reserves are in Chiapas, Mexico. We used five techniques: flotation, MacMaster, micrometric, Ritchie's sedimentation and Ferreira's quantitative. In addition, we collected ectoparasites from animals captured in both reserves and from a captive couple from Tuxtla Gutierrez, Chiapas. These nematodes and protozoans were found: Agriostomun sp., Lacandoria sp., Neomurshidia sp., Trichostrongylus sp., Strongylus sp., Brachylumus sp, and an unidentified species of ancilostomaide. We also found Eimeria sp. and Balantidium coli, as well as the mites Dermacentor halli, Dermacentor latus, Amblyomma cajannense, Amblyomma coelebs, Amblyomma ovale, Anocentor nitens and Ixodes bicornis. 相似文献
47.
48.
T. Ripperger B. Schlegelberger PD Dr. rer. nat. D. Steinemann 《Medizinische Genetik》2012,24(1):33-39
Juvenile myelomonocytic leukemia (JMML) is a unique myeloproliferative disorder of early childhood in which mutations in NRAS, KRAS, PTPN11, NF1 and CBL are frequently found. Using high-resolution oligo array-based comparative genomic hybridization (aCGH), 20 JMML samples were investigated for submicroscopic genomic copy number alterations. Besides known cytogenetic aberrations, ten samples displayed additional submicroscopic alterations. Interestingly, an almost identical gain of chromosome 8 was identified in two patients. Subsequently, fluorescence in situ hybridization indicated a constitutional partial trisomy 8 mosaic (cT8M) in both patients. A survey on 27 cT8M patients with reported malignancies showed a predominance of myeloid malignancies including JMML. Our results dramatically reduce the critical region on chromosome 8 to 8p11.21q11.21. To determine how constitutional partial trisomy 8 mosaicisms may contribute to leukemogenesis in different mutational subtypes of JMML and other myeloid malignancies, further investigations are required. 相似文献
49.
Pimentel GD Dornellas AP Rosa JC Lira FS Cunha CA Boldarine VT de Souza GI Hirata AE Nascimento CM Oyama LM Watanabe RL Ribeiro EB 《The Journal of nutritional biochemistry》2012,23(7):822-828
Hypothalamic insulin inhibits food intake, preventing obesity. High-fat feeding with polyunsaturated fats may be obesogenic, but their effect on insulin action has not been elucidated. The present study evaluated insulin hypophagia and hypothalamic signaling after central injection in rats fed either control diet (15% energy from fat) or high-fat diets (50% energy from fat) enriched with either soy or fish oil. Soy rats had increased fat pad weight and serum leptin with normal body weight, serum lipid profile and peripheral insulin sensitivity. Fish rats had decreased body and fat pad weight, low leptin and corticosterone levels, and improved serum lipid profile. A 20-mU dose of intracerebroventricular (ICV) insulin inhibited food intake in control and fish groups, but failed to do so in the soy group. Hypothalamic protein levels of IR, IRS-1, IRS-2, Akt, mTOR, p70S6K and AMPK were similar among groups. ICV insulin stimulated IR tyrosine phosphorylation in control (68%), soy (36%) and fish (34%) groups. Tyrosine phosphorylation of the pp185 band was significantly stimulated in control (78%) and soy (53%) rats, but not in fish rats. IRS-1 phosphorylation was stimulated only in control rats (94%). Akt serine phosphorylation was significantly stimulated only in control (90%) and fish (78%) rats. The results showed that, rather than the energy density, the fat type was a relevant aspect of high-fat feeding, since blockade of hypothalamic insulin signal transmission and insulin hypophagia was promoted only by the high-fat soy diet, while they were preserved in the rats fed with the high-fat fish diet. 相似文献
50.
PD Dr. Stefan Pelzer 《当今生物学》2012,42(2):98-106
Tailor‐made microorganisms Microbial diversity provides unlimited resources for the development of novel industrial processes and products. Since the beginning of the 20th century microorganisms have been successfully applied for the large scale production of bio‐based products. In recent years, modern methods of strain development and Synthetic Biology have enabled biotech engineers to design even more sophisticated and tailor‐made microorganisms. These microbes serve industrial processes for the production of bulk chemicals, enzymes, polymers, biofuels as well as plant‐derived ingredients such as Artemisinin in an ecologically and economically sustainable and attractive fashion. In the future, production of advanced biofuels, microbial fuel cells, CO2 as feedstock and microbial cellulose are research topics as well as challenges of global importance. Continuous efforts in microbiology and biotechnology research will be pivotal for white biotechnology to gain more momentum in transforming the chemical industry towards a knowledge based bio‐economy. 相似文献