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排序方式: 共有809条查询结果,搜索用时 15 毫秒
721.
Md. Mijan Hossain Chiharu Tani Tomoko Suzuki Fumiko Taguchi Tatsuhiro Ezawa Yuki Ichinose 《Physiological and Molecular Plant Pathology》2008,72(4-6):122-127
Polyphosphate kinase (PPK), encoded by the ppk gene, is a principal enzyme responsible for synthesis of inorganic polyphosphate (poly P) from ATP in many Gram-negative bacteria. In order to elucidate the functions of poly P in Pseudomonas syringae pv. tabaci 6605, an in-frame deletion mutant of the ppk gene (ppk) was constructed. The ppk mutant did not accumulate poly P, whereas the wild-type strain accumulated a large quantity. The mutant had reduced swarming motility, even though it retains swimming motility like the parental strain. The mutant exhibited increased sensitivity to prolonged incubation and environmental stresses, such as heat shock and oxidative stress and reduced exopolysaccharide (EPS) production compared to the wild-type. Northern blot analysis revealed that expression of the rpoS gene, encoding the stationary phase sigma factor RpoS, was reduced in ppk in the logarithmic phase, indicating that rpoS is regulated by the ppk gene. The poly P deficient mutant had significantly reduced ability to cause disease in its host tobacco plant and in planta growth of the mutant was also significantly reduced in host tobacco leaves as compared to the wild-type strain. Thus, our results suggest that poly P plays an important role in the virulence of P. syringae pv. tabaci 6605. 相似文献
722.
Mohammad Anwar Hossain Mirza Hasanuzzaman Masayuki Fujita 《Frontiers of Agriculture in China》2011,5(1):1-14
The purpose of this study was to assess the synergistic effects of exogenously applied proline and glycinebetaine (betaine)
in antioxidant defense and methylglyoxal (MG) detoxification system in mung bean seedlings subjected to salt stress (200 mmol·L−1 NaCl, 48 h). Seven-day-old mung bean seedlings were exposed to salt stress after pre-treatment with proline or betaine. Salt
stress caused a sharp increase in reduced glutathione (GSH) and oxidized glutathione (GSSG) content in leaves, while the GSH/GSSG
ratio and ascorbate (AsA) content decreased significantly. The glutathione reductase (GR), glutathione peroxidase (GPX), glutathione
S-transferase (GST) and glyoxalase II (Gly II) activities were increased in response to salt stress, while the monodehydroascorbate
reductase (MDHAR), dehydroascorbate reductase (DHAR), catalase (CAT) and glyoxalase I (Gly I) activities sharply decreased
with an associated increase in hydrogen peroxide (H2O2) and lipid peroxidation level (MDA). Proline or betaine pre-treatment had little influence on nonenzymatic and enzymatic
components as compared to those of the untreated control. However, proline or betaine pre-treated salt-stressed seedlings
showed an increase in AsA, GSH content, GSH/GSSG ratio and maintained higher activities of APX, DHAR, GR, GST, GPX, CAT, Gly
I and Gly II involved in ROS and MG detoxification system as compared to those of the untreated control and mostly also salt-stressed
plants with a simultaneous decrease in GSSG content, H2O2 and MDA level. These results together with our previous results suggest that coordinate induction of antioxidant defense
and glyoxalase system by proline and betaine rendered the plants tolerant to salinity-induced oxidative stress in a synergistic
fashion. 相似文献
723.
Poor grain filling induced by waterlogging is similar to that in abnormal early ripening in wheat in Western Japan 总被引:3,自引:0,他引:3
Abnormal early ripening (AER), a major constraint on wheat production in Western Japan, manifests as sudden leaf senescence shortly after anthesis and results in poor grain filling; this leads to smaller grains and reduced grain yield. It is suggested that overwetting of the soil may be related to AER. We conducted field experiments over 2 seasons (2008-2009 and 2009-2010) in Yamaguchi, Western Japan, with waterlogging treatment using 2 Japanese wheat cultivars, Daichinominori (Western Japanese cultivar) and Haruyutaka (Hokkaido cultivar), which differ in terms of grain growth in the environment of Western Japan. We imposed pre-anthesis waterlogging for 2 weeks in 2008-2009 and post-anthesis waterlogging throughout the grain-filling period in 2009-2010. Pre-anthesis waterlogging had no significant effect on grain yield or grain filling irrespective of cultivar. Post-anthesis waterlogging severely reduced the grain yield by 44% and 36% in Haruyutaka and Daichinominori, respectively. The yield loss was attributable to the smaller grain weight that was a result of slower grain growth rate later in the shortened grain-filling period. Post-anthesis waterlogging induced sudden leaf senescence 1 and 2 weeks after anthesis in Haruyutaka and Daichinominori, respectively, and drastically reduced the photosynthesis and ultimately dry mass accumulation. It also depressed the remobilization of water-soluble carbohydrates (WSCs) from culms to grains leaving more residual WSCs in the culms at harvest (149 and 65 mg g−1 DW in waterlogging and controls, respectively). The results indicate that the reduced grain growth due to waterlogging was attributable to decreased current assimilation and poor remobilization of culm WSCs to grain similar to that in AER plants. These results suggest that injured root function after anthesis might induce early leaf senescence and poor grain filling similar to AER wheat. 相似文献
724.
Soil slaking is an environment-friendly technique that is gaining importance in restoring saline soils. The objective of this
article is to evaluate the effect of initial water content (IWC) on saturated hydraulic conductivity (K
s) in desalinization with slaking and drying. Accordingly, a slaking test was carried out during February, 2009 for evaluating
the effects of slaking and drying on K
s, sodium adsorption ratio (SAR) and exchangeable sodium percentage (ESP) under various IWC. We prepared natural and air-dried
soils of paddy field in Kojima Bay Polder, Japan to give different pre-drying, air-dried, and not dried (natural). The air-dried
soils were resaturated. Each soil was well mixed, then dried to different initial moisture contents (60, 50, 40, 30, 20, and
10% by weight). The specimens were immersed into water in the pot for 24 h. The K
s was measured, and cations in slaked and unslaked soils were analyzed. The K
s was high under the water content below 30% in both the natural and the air-dried soils. But the effects were more pronounced
in the natural soil. The air-dried soil showed far smaller K
s than the natural soil. In outer solution, the highest SAR was noted at 30% in the natural and 30 and 20% in the air-dried
soils. Significant decrease in ESP of the soils (slaked + unslaked) was also observed at the same water content. Lower water
content was more effective in decreasing the soil ESP after desalinization from saline soil. The natural soil showed lower
ESP and higher porosity, which was considered as a reason for higher K
s of natural soil than that of air-dried soils. The results indicated that lower water content (10–30%) had no hazardous effect
on K
s by slaking and drying of soil. 相似文献
725.
Hyun Ah Jung Md. Nurul Islam Chan Mee Lee Hyong Oh Jeong Hae Young Chung Hee Chul Woo Jae Sue Choi 《Fisheries Science》2012,78(6):1321-1329
In the present study, we investigated the antidiabetic potential of fucoxanthin via the inhibition of rat lens aldose reductase (RLAR), human recombinant aldose reductase (HRAR), advanced glycation end-product (AGE) formation, protein tyrosine phosphatase 1B (PTP1B), and α-glucosidase. Fucoxanthin displayed potent inhibitory activity against AGE formation and HRAR and RLAR activity. In addition, fucoxanthin showed potent inhibitory activity against PTP1B. However, it did not show α-glucosidase inhibitory activity below 200 μM. In addition, our kinetic study revealed that fucoxanthin competitively inhibited RLAR, while it showed mixed-type inhibition against PTP1B. In order to confirm enzyme inhibition, we predicted the 3D structure of PTP1B using Autodock 4.0 to simulate the binding of fucoxanthin. Docking simulation results demonstrated that three residues of PTP1B (Phe30, Phe52, and Gly183) interact with the two hydroxyl groups of fucoxanthin. In addition, the binding energy was negative (?7.66 kcal/mol), indicating that the three hydrogen bonds may stabilize the open form of the enzyme and potentiate tighter binding to the active site of PTP1B, resulting in more effective PTP1B inhibition. The results of the present study therefore clearly demonstrate the promising potential of fucoxanthin as a therapeutic intervention for the management of diabetes as well as diabetes-associated complications, which could be explored further. 相似文献
726.
Md. Iqbal Faruk Masatoshi Izumimoto Nobuhiro Suzuki 《Journal of General Plant Pathology》2008,74(6):425-433
The type virus of the family Hypoviridae,
Cryphonectria hypovirus 1 strain EP713 (CHV1-EP713), infects Cryphonectria parasitica, the filamentous causal fungus of chestnut blight, and reduces its virulence. This pathosystem serves as a model to study
fungus-mycovirus interactions. We previously developed a genetic screening protocol for host factors associated with symptom
induction by CHV1-EP713 and its mutants. In the procedure the standard field fungal isolate EP155 was transformed by cDNA
from a mild hypovirus mutant Cys(72), launching virus infection, and mutagenized by random plasmid insertion with pHygR conferring
hygromycin resistance. We now report an extension of the study to characterize different mutant strains, with different phenotypes
than their parental strain TCys(72)-1. TCys(72)-1 is moderately reduced in pigmentation and sporulation compared to the uninfected
wild-type strain EP155. Mutants sfb1, sfb2 and k202 were characterized biologically and molecularly in comparison to the previously
isolated mutant (namA) and the parental strain. These mutants harbored one (sfb1) or more copies (sfb2 and k202) of the mutagenic plasmid, pHygR.
The three mutants had similar biological attributes; that is, vegetative growth rate, conidiation and virulence (assay on
apples) was reduced on potato dextrose agar media, relative to the parental strain and pigmentation was the same or slightly
increased. Interestingly, viral dsRNA accumulation levels were apparently unaltered in these mutants. The screening method
was efficient for mining fungal mutants with unusual hypovirus symptoms. Further, characterization of the mutants provides
interesting insights into symptom induction by the hypovirus. 相似文献
727.
The experiment was carried out to evaluate the production performance of sutchi catfish, Pangasianodon hypophthalmus in restricted feeding regimes and their effects on gut and liver indices and body composition. Four feeding regimes were evaluated: fed to satiation twice per day (treatment daily feeding); 1‐day food deprivation and 1‐day feeding (treatment 1D‐1F), 2‐day deprivation and 2‐day feeding (treatment 2D‐2F) and 5‐day deprivation and 5‐day feeding (treatment 5D‐5F). Fingerlings (mean weight 37 ± 3 g, mean total length 18 ± 2 cm) were stocked in replicated earthen ponds at a density of 25 000 ha?1 and cultured for 18 weeks during which commercial diet (33% crude protein) were delivered to apparent satiation on the feeding day according to the treatment. Results showed that the daily feeding and 1D‐1F treatments resulted in similar individual weight gain (515–536 g) and net fish production (10 954–11 387 kg ha?1) as compared with treatment 2D‐2F (weight gain 309 g; net production 6700 kg ha?1) or treatment 5D‐5F (weight gain 251 g; net production 5651 kg ha?1). While fish body protein levels were not affected by food deprivation, lipid contents were lowest in treatments 2D‐2F and 5D‐5F. The study concluded that sutchi catfish could be cultured in alternate‐day feeding regime without any negative effects on production and meat quality of fish resulting in a net profit of USD 2750 ha?1 pond. 相似文献
728.
孟加拉森林保护区系统综述 总被引:1,自引:0,他引:1
孟加拉目前共建立了19个保护区,包含了该国家全部4种森林类型。这些保护区既可以保存生物多样性,也为当地群众维持生计提供资源。一直以来,各个保护区由国家林业局统一管理以确保森林的可持续性:近期,一项共同管理措旌开始在5个保护区试点,借此发展参与森林保护的伙伴。此项措施已经产生一些积极的影响,还要适当的附加限制的发挥积极性,确保共同参与这项措施获得成功,推进正在进行的保护计划。本文综述了已发表的研究成果、政府和项目文件,来分析保护区的现状,并给出相应的建议。 相似文献
729.
Homegardens around the world often exhibit remarkable variation in composition and structure depending on the physiographic
and climatic conditions of the area and a wide variety of household characteristics. This research investigated whether households’
contextual attributes have a quantitative and predictable relationship with homegarden vegetation structure from a total of
402 randomly selected households in southwestern Bangladesh. The central analytical tool to test the relationship between
household characteristics and the homegarden vegetation structure was multiple regression. The moderate to low regression
R
2 values revealed that most household characteristics were not strong predictors of homegarden vegetation structure. Despite
the weak explanatory power of the majority household characteristics, time spent and homestead size had the strongest relationship
with species richness and income in a homegarden. Households being the main source of labor for a majority of households suggest
that outside labor shortage would not influence homegarden vegetation structure. We suggest that women’s active participation
in homegardening activities to reduce gender inequality in the family which will perhaps result in more diverse and economically
viable homegarden. However, increasing population density and the concomitant fragmentation of landholdings to homesteads
may create opportunity for homegarden promotion in Bangladesh. Our results of decreased species richness in the homegarden
with improved roads and proximity to market support the general hypothesis of subsistence homegardens and did not reinforce
the general fears of gradual decline in species richness due to a market economy. Household characteristics had no influence
on the presence of IUCN Red Listed species in the homegarden, except for gender and education of the household head. However,
most homegardeners were unaware about the status of red listed species, suggesting that occurrence of red listed species in
homegardens was by chance. Thus, efforts to improve awareness and to save and conserve rare species from extirpation are needed. 相似文献
730.
Sayma Akhter Md. Abdul Halim Md. Shawkat Islam Sohel Swapan Kumar Sarker Mohammad Shaheed Hossain Chowdhury Sanjay Saha Sonet 《林业研究》2008,19(1):72-78
This review describes the non-timber forest products (NTFPs) used for different aspects of beauty-care in Bangladesh on the basis of extensive literature survey. The diverse plant species, including used parts and using patterns for hair care, facial treatments and body care, were summarized in 13 tables. This paper accumulate the scattered knowledge regarding the use of plants in beauty-care in Bangladesh, to draw the extent of use of NTFPs in health care and to record the knowledge for assessing the possibilities of further implementation in herbal cosmetics industries. The structured knowledge can be used in policy making process for sustainable management of these valuable NTFPs leading to the conservation of the country's biological diversity. It is suggested that intensive field level research is necessary for securing sustainability of NTFPs. 相似文献