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21.
ABSTRACT

Root exudate is derived from plant metabolites and its composition is affected by plant nutrient status. A deficiency of mineral nutrients, such as nitrogen (N) and phosphorus (P), strongly affects the type and amount of plant metabolites. We applied a metabolite profiling technique to investigate root exudates of rice plants under N and P deficiency. Oryza sativa was grown in culture solution containing two N levels (0 and 60 mg N L?1) or two P levels (0 and 8 mg P L?1). Shoot extracts, root extracts, and root exudates were obtained from the rice plants 5 and 15 days after transplanting and their metabolites were determined by capillary electrophoresis/time-of-flight mass spectrometry. Shoot N concentration and dry weight of rice plants grown at ?N level were lower than those of plants grown at +N level. Shoot P concentration and dry weight of rice plants grown at ?P level were lower than those of plants grown at +P level. One hundred and thirty-two, 127, and 98 metabolites were identified in shoot extracts, root extracts, and root exudates, respectively, at the two N levels. One hundred and thirty-two, 128, and 99 metabolites were identified in shoot extracts, root extracts, and root exudates, respectively, at the two P levels. Seventy-seven percent of the metabolites were exuded to the rhizosphere. The concentrations of betaine, gamma-aminobutyric acid, and glutarate in root exudates were higher at both ?N and ?P levels than at their respective high levels. The concentration of spermidine in root exudates was lower at both ?N and ?P levels than at their respective high levels. The concentrations of the other metabolites in root exudates were affected differently by plant N or P status. These results suggest that rice roots actively release many metabolites in response to N and P deficiency.  相似文献   
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A mutant strain, PBA322, was constructed by electroporation of a phagemid containing the coding region of antisense RNA of the ompH gene, encoding 39 kDa capsular protein or OmpH, into the parental strain P-1059 (serovar A:3) of Pasteurella multocida, and the pathogenicity was determined in mice and chickens. Grayish colonies of the mutant, indicating loss of capsule synthesis, were observed under a stereomicroscope using obliquely transmitted light, while iridescent colonies were observed for the parental strain. Moreover, strain PBA322 showed a low amount of OmpH compared with the parental strain on SDS-PAGE. Additionally, the capsule of strain PBA322 was thinner than that of the parental strain according to electron microscopy, correlating to the attenuation against chickens. In conclusion, strain PBA322, the mutant of P. multocida strain P-1059, was completely attenuated for chickens.  相似文献   
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Many metabolic hormones, growth hormone (GH), insulin-like growth factor-I (IGF-I) and insulin affect ovarian functions. However, whether ovarian steroid hormones affect metabolic hormones in cattle remains unknown. This study aimed to determine the effect of sex steroids on the plasma profiles of GH, IGF-I and insulin and their receptors in the liver and adipose tissues of dairy cows. Ovariectomized cows (n = 14) were randomly divided into four groups: control group (n = 3) was treated with saline on Day 0; oestradiol (E2) group (n = 3), with saline and 1 mg oestradiol benzoate (EB) on Day 0 and 5, respectively; progesterone (P4) group (n = 4) with two CIDRs (Pfizer Inc., Tokyo, Japan) from Day 0; and E2 + P4 group (n = 4) with two CIDRs on Day 0 that were removed on Day 6 and were immediately injected with 1 mg EB. The animals were euthanized after the experiment, and liver and adipose tissues samples were quantitatively analysed using real-time PCR for the expression of mRNA for the GH (GHR), IGF-I (IGFR-I) and insulin (IR) receptor mRNAs. Oestradiol benzoate significantly increased the number of peaks (p < 0.05), pulse amplitude (p < 0.05) and area under the curve (AUC; p < 0.01) for plasma GH; moreover, it increased plasma IGF-I concentration (p < 0.05), but it had no effect on the plasma insulin profile. P4 significantly decreased the AUC (p < 0.01), compared with the control group, whereas it did not affect the number of peaks and the amplitude of GH pulses. P4 + E2 did not affect the GH pulse profile. E2 increased the mRNA expression of GHR, IGFR-I and IR in the liver (p < 0.05), whereas both P4 and E2 + P4 did not change their expressions. Our results provide evidence that the metabolic and reproductive endocrine axes may regulate each other to ensure optimal reproductive and metabolic function.  相似文献   
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The effect of Bacillus licheniformis HA1 cell density on the acceleration of organic waste composting was tested in a bench-scale composting system utilizing a process limit temperature of 60°C. Variables measured during composting were CO2 evolution rate, conversion of substrate carbon and pH. When an initial cell density of 2.0×104 cfu/g-dry solid was used, the strain HA1 increased in number and prevented the decrease in pH during the early stage of composting. This resulted in enhanced populations of other thermophiles and increased the rate of organic matter decomposition. By contrast, no effect was observed at a lower cell density of HA1. It was found that the minimum cell density of HA1 to accelerate organic decomposition was around 104-105 cfu/g dry solid of raw material.  相似文献   
26.
The extracellular matrix surrounding the oocyte before ovulation is called the perivitelline membrane (PL) in avian species. The PL is constructed with two major glycoproteins, ZPC and ZP1, which are synthesized in the ovarian granulosa cells and the liver, respectively. Although the properties of the major components in the PL have been examined, knowledge about the nature of its minor constituents is lacking. In this study we focused on PL protein, which migrates at 46‐kDa in the gel of SDS‐PAGE. N‐terminal sequence analysis demonstrated that the 46‐kDa protein is the C‐terminal fragment of ZP1. Analysis of lysylendopeptidase digests or cyanogens bromide‐degraded fragments of ZP1 confirmed this postulate. Western blot analysis using antiserum against 46‐kDa protein indicated the absence of 46‐kDa protein in the serum. Moreover, small immunoreactive bands, thought to be cleaved fragments of ZP1, were detected in the PL lysate by western blot analysis using antiserum against the N‐terminal peptide of ZP1. These results indicated that the N‐terminal proteolytic processing of ZP1 might take place after the arrival of ZP1 at the ovary, and the resulting product, 46‐kDa protein, is incorporated into the PL.  相似文献   
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Paddy and Water Environment - In recent years, Paddy Field Dams have received recognition as a measure to alleviate flooding due to torrential rains. Paddy Field Dams have been in practice in...  相似文献   
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We investigated the effect of dietary phytase on the true absorption and endogenous fecal excretion of zinc (Zn) using 67Zn in growing pigs given a corn-soybean meal based diet. Ten crossbred barrows were fed the control diet containing 90-mg/kg Zn, 2.3-g/kg phytate-phosphorus and 3.7-g/kg non-phytate-phosphorus or the phytase diet containing similar amounts of Zn and phytate-phosphorus, and 1.4-g/kg non-phytate-phosphorus with 750-PU/kg phytase for 12 h/day. On day 6, the pigs were given 200 g of the corresponding diet labeled by 67Zn for 2 h. We measured feed intake, fecal Zn concentration and 67Zn abundance for the determination of apparent absorption, true absorption and endogenous fecal excretion of Zn. Although the apparent absorption of Zn did not significantly differ between the dietary groups, the phytase group had significantly more ( P  < 0.05) true absorption of Zn than the control group. The endogenous fecal excretion of Zn tended to be more ( P  = 0.07) in the phytase group than in the control group. These results suggest that dietary phytase improves Zn bioavailability through increasing the true absorption of Zn in growing pigs, which results in stimulating the endogenous fecal excretion of Zn when dietary Zn satisfies its requirement.  相似文献   
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