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141.
Lien WH Klezovitch O Fernandez TE Delrow J Vasioukhin V 《Science (New York, N.Y.)》2006,311(5767):1609-1612
During development, cells monitor and adjust their rates of accumulation to produce organs of predetermined size. We show here that central nervous system-specific deletion of the essential adherens junction gene, alphaE-catenin, causes abnormal activation of the hedgehog pathway, resulting in shortening of the cell cycle, decreased apoptosis, and cortical hyperplasia. We propose that alphaE-catenin connects cell-density-dependent adherens junctions with the developmental hedgehog pathway and that this connection may provide a negative feedback loop controlling the size of developing cerebral cortex. 相似文献
142.
Hashem A Hossein MS Woo JY Kim S Kim JH Lee SH Koo OJ Park SM Lee EG Kang SK Lee BC 《The Journal of reproduction and development》2006,52(5):591-599
The present study was conducted to examine the comparative efficacy of potassium simplex optimization medium (KSOM) and North Carolina State University (NCSU)-23 medium supplemented with beta-mercaptoethanol (beta-ME) and amino acids (AA) on the developmental competence of porcine in vitro fertilized (IVF) embryos. Four experiments were conducted. KSOM and NCSU-23 medium were used to culture porcine parthenogenetic (Exp. 1) and IVF (Exp. 2) embryos. KSOM and NCSU-23 were equally effective in supporting porcine parthenogenetic and IVF embryo development from the 1-cell stage to blastocysts. The NCSU-23 medium (Exp. 3) and KSOM (Exp. 4) were supplemented with amino acid (AA; 5 microl/ml non-essential amino acids + 10 microl/ml essential amino acids) and/or 10 microM beta-mercaptoethanol (beta-ME). The quality of blastocysts from Exp. 3 and 4 was evaluated by counting the number of total cells and determining the ratio of the inner cell mass (ICM) to trophoectoderm (TE) cells. Supplementing with AA and beta-ME or beta-ME alone in NCSU-23 produced significant (p<0.05) differences in terms of rate of cleavage to the 2- to 4- cell (80.8 to 85.4% vs. 73.6%) and blastocyst (30.4 to 30.5 vs. 23.5%) stages and the number of TE (51.4 to 53.8 vs. 35.8) and total cells (67.2 to 71.2 to 48.8) over the control group. On the other hand, supplementing KSOM with AA and/or beta-ME produced significant (p<0.05) differences in terms of rate of cleavage to the 2- to 4-cell (78.8% vs. 67.7%) and morula (57.8% vs. 46.3%) stages and the number of ICM (18.6 to 19.2 vs. 11.6) and total cells (62.8 to 70.6 vs. 42.8) over control group. In conclusion, our study demonstrates that both KSOM and NCSU-23 medium supplemented with AA and beta-ME and/or only beta-ME alone are superior to normal KSOM and NCSU-23 for porcine IVF embryo culture in terms of embryo developmental competence and quality. 相似文献
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144.
Hicsasmaz Z Dogan E Chu C Rizvi SS 《Journal of agricultural and food chemistry》2003,51(21):6191-6197
Yeast-leavened dough processing is semicontinuous due to the requirement for fermentation at constant temperature and humidity. Also, new regulations on the emission of alcohols are becoming burdensome on the baking industry. Extrusion processing of dough with supercritical carbon dioxide (SC-CO(2)) is envisioned to alleviate emission problems and to decrease production time by eliminating fermentation. A bread dough formulation with 50% (w/w) moisture was leavened by injecting 1.5% (w/w) SC-CO(2) in a twin-screw extruder at 37 degrees C. Specific mechanical energy input was 260 kJ/kg. The operating apparent shear rate range was 60-260 s(-1). SCFX-leavened dough density (420-430 kg/m(3)) was in good agreement with values reported for similar doughs. The flow behavior index, obtained by an on-line slit rheometer, was 0.49 for the nonleavened control and 0.63 for the SCFX-leavened dough. Apparent viscosity of the SCFX-leavened dough varied from 37 to 23 Pa-s. This new continuous process offers attractive possibilities for industrial applications if further developed. 相似文献
145.
Saxifraga hirculus is a postglacial relict in Central Europe, whose populations suffered a dramatic decrease in the 19th and 20th centuries. However, few researchers have been interested in its ecological requirements in Central Europe. This article synthesizes previous knowledge supplemented by original data from the last large population (Switzerland).S. hirculus is a weak competitor which needs precise ecological conditions. It grows on bryophyte carpets in neutral to slightly acid wetlands, with stable water table close to the soil surface (optimum between 8 and 14 cm) but does not stand long flooding. However, it requires a good oxygen supply, with roots 2-3 cm under the soil surface, generally not reached by water, with running, cold water through loose, fibric peat. Its optimal conditions are in spring fens, but it grows in other types of wetlands as well. However, overgrowing by shrubs, sedges or Sphagnum in natural successions may threaten the species with extinction, as did drainage and peat extraction previously. Now, its survival in Central Europe depends on an adequate management of the ecosystems. Moderate grazing (cattle or sheep) or mowing help to limit competition with taller Carex species. Reintroduction of disappeared populations or creation of new ones from cultivation in botanical garden is possible, but appropriate sites are rare. In some cases, substrate management could improve the conditions in somewhat inadequate situations. This management in four directions can be flexibly applied in different situations to progress to optimal conditions for the conservation of this valuable species. 相似文献
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148.
Tania Bobbo Chiara Roveglia Mauro Penasa Giulio Visentin Raffaella Finocchiaro Martino Cassandro 《Animal Science Journal》2019,90(7):808-817
The aim of this study was to estimate genetic associations between alternative somatic cell count (SCC) traits and milk yield, composition and udder type traits in Italian Jersey cows. Alternative SCC traits were test‐day (TD) somatic cell score (SCS) averaged over early lactation (SCS_150), standard deviation of SCS of the entire lactation (SCS_SD), a binary trait indicating absence or presence of at least one TD SCC >400,000 cells/ml in the lactation (Infection) and the ratio of the number of TD SCC >400,000 cells/ml to total number of TD in the lactation (Severity). Heritabilities of SCC traits, including lactation‐mean SCS (SCS_LM), ranged from 0.038 to 0.136. Genetic correlations between SCC traits were moderate to strong, with very few exceptions. Unfavourable genetic associations between milk yield and SCS_SD and Infection indicated that high‐producing cows were more susceptible to variation in SCC than low‐producing animals. Cows with deep udders, loose attachments, weak ligaments and long teats were more susceptible to an increase of SCC in milk. Overall, results suggest that alternative SCC traits can be exploited to improve cow's resistance to mastitis in Italian Jersey breed. 相似文献
149.
Tania San Pedro Rosa Peiró Carles Jiménez Antonio Olmos 《The Journal of Horticultural Science and Biotechnology》2018,93(1):19-25
In vitro culture represents a tool for the ex situ conservation of a high number of sanitised plants in a reduced space. However, the culture media and/or other growing conditions need to be optimised to minimising plant growth and storage cost. Growth on MW medium was evaluated in the commercial cultivars ‘Airén’, ‘Bobal’, ‘Chardonnay’, ‘Garnacha Blanca’, ‘Moscatel de Alejandría’, ‘Moscatel de Grano Menudo’, ‘Pedro Ximénez’, ‘Pinot Blanc’, ‘Pinot Gris’, ‘Sauvignon Blanc’, and ‘Tempranillo’; the minor cultivars ‘Chelva’, ‘Valencí Negre’, ‘Valencí Blanc’, and ‘Verdil’; and the endangered cv. ‘Esclafacherre’. Different growth rates were observed among cultivars: those with faster growth need to be subcultured every 1.5–2.0 months; those with the slowest growth every 3.5–4.0 months. The effect of halving the sucrose in MW reduced the growth of the cultivars that grew faster without compromising survival. When IBA was removed from MW, growth was also reduced in some cultivars. Therefore, small modifications of the MW composition are adequate for grapevine in vitro storage under standard incubation conditions. This is an advantage with respect to the change of temperature used in other work to achieve growth reduction, and allows the use of the same chamber for different in vitro culture procedures. 相似文献
150.
Spinach (Spinacea oleracea L. cv. ‘Banarasi’), known to be responsive to potentially toxic elements, was investigated for chromium (Cr6 +) effect on iron metabolism and water relations. After 40 days growth in sand culture, a set of plants was supplied with 100 and 400 μM Cr6 + (potassium dichromate, K2Cr2O7), superimposed over the complete nutrient solution (control). Excess Cr6 + produced visual symptoms of toxicity and increased accumulation of Cr, more in roots than in leaves. Decreased concentration of chlorophylls and the activities of heme enzymes, catalase and peroxidase in excess Cr6 + may suggest interference of Cr in iron metabolism of plants. These changes associated with decrease in iron (Fe) accumulation in Cr6 + treated plants, indicate that by reducing absorption of Fe, Cr6 + impairs the Fe requiring steps of chlorophyll and heme biosynthesis. In spite of lower water saturation deficit, the leaves of Cr6 + treated plants showed a decrease in leaf water potential, associated with increase in diffusive resistance and lowering of transpiration rate along with proline accumulation indicates water stress. The changes observed in water stress parameters in Cr6 + treated plants indicate that excess supply of Cr6 + reduces the physiological availability of water. 相似文献