全文获取类型
| 收费全文 | 506篇 |
| 免费 | 4篇 |
专业分类
| 林业 | 53篇 |
| 农学 | 20篇 |
| 基础科学 | 12篇 |
| 76篇 | |
| 综合类 | 40篇 |
| 农作物 | 29篇 |
| 水产渔业 | 75篇 |
| 畜牧兽医 | 154篇 |
| 园艺 | 5篇 |
| 植物保护 | 46篇 |
出版年
| 2024年 | 5篇 |
| 2023年 | 5篇 |
| 2022年 | 5篇 |
| 2021年 | 6篇 |
| 2020年 | 23篇 |
| 2019年 | 34篇 |
| 2018年 | 21篇 |
| 2017年 | 24篇 |
| 2016年 | 23篇 |
| 2015年 | 22篇 |
| 2014年 | 23篇 |
| 2013年 | 42篇 |
| 2012年 | 23篇 |
| 2011年 | 30篇 |
| 2010年 | 25篇 |
| 2009年 | 19篇 |
| 2008年 | 26篇 |
| 2007年 | 15篇 |
| 2006年 | 16篇 |
| 2005年 | 17篇 |
| 2004年 | 15篇 |
| 2003年 | 10篇 |
| 2002年 | 15篇 |
| 2001年 | 5篇 |
| 2000年 | 8篇 |
| 1999年 | 8篇 |
| 1997年 | 4篇 |
| 1996年 | 3篇 |
| 1995年 | 1篇 |
| 1994年 | 1篇 |
| 1993年 | 2篇 |
| 1992年 | 2篇 |
| 1991年 | 2篇 |
| 1990年 | 1篇 |
| 1988年 | 4篇 |
| 1986年 | 2篇 |
| 1985年 | 1篇 |
| 1984年 | 1篇 |
| 1983年 | 2篇 |
| 1982年 | 2篇 |
| 1979年 | 1篇 |
| 1978年 | 2篇 |
| 1977年 | 3篇 |
| 1975年 | 1篇 |
| 1972年 | 1篇 |
| 1971年 | 2篇 |
| 1970年 | 1篇 |
| 1968年 | 2篇 |
| 1928年 | 1篇 |
| 1926年 | 1篇 |
排序方式： 共有510条查询结果，搜索用时 15 毫秒
51.
Ghazi N. Al‐Karaki 《Journal of plant nutrition》2013,36(3):369-379
Salinity tolerance in some plant species has been related to characteristics of potassium (K) and sodium (Na) uptake and transport. Tomato (Lycopersicon esculentum Mill., cv. Rossel) plants were grown in nutrient solution to determine effects of two K levels [0.2 (low) and 2 mmol (high)] combined with 0, 100, and 200 mmol NaCl on growth, and on Na and K uptake and translocation. Net uptake rates of Na and K were determined by disappearance in the growth medium and by plant accumulation. At the low level of K in solution, salinity decreased shoot and root dry weight and leaf area. Addition of 2 mmol K ameliorated of the added NaCl effects and improved growth parameters. Salinity reduced net K uptake rates and to a lesser extent K translocation from root to shoot, which resulted in higher K shoot concentration and a lower K root concentration. The inhibitory effect of salinity on K translocation was greater with low K level in nutrient solution. Net uptake of K was dependent on K level in the growth medium. Addition of K resulted in decreases of shoot Na uptake. The translocation of Na from roots to shoots was reduced by K level in nutrient solution. These results indicate that K supply and K accumulation and regulation in plant tissue contribute to salt tolerance and growth enhancement. 相似文献
52.
A field calibration experiment was carried out on salt‐affected clayey soil in Syria, to compare the sensitivity to soil electrical conductivity (ECe), and bulk density (ρb) of two instruments for estimating soil moisture: the neutron probe (NP) and the Diviner 2000 capacitance probe (CP). The results showed that the values of the correlation coefficient of the calibration were decreased when the ECe and ρb values increased; this decrease was more pronounced for the Diviner 2000, indicating that it was more sensitive to ρb and ECe than the NP. When only scaled frequency was used in the fitted equation, the Diviner 2000 in wet soil underestimated soil water content significantly at all depths, but especially in the top layer, by up to 0.09 cm3/cm3 compared with gravimetric determinations. However, in dry soil, the Diviner 2000 overestimated the volumetric water content by up to 0.05 cm3/cm3 in the top 15 cm, and by 0.03 cm3/cm3 at 30‐45 cm depth. The performance of the neutron probe was better overall; using a factory calibration curve no significant differences were observed between NP estimates and the gravimetric values. Including both ρb and ECe in the calibration equations improved the fits, although the regression coefficient (R2) for the Diviner 2000 remained low. 相似文献
53.
Hridam Deb Shili Xiao Mohammad Neaz Morshed Shamim Al Azad 《Fibers and Polymers》2018,19(8):1715-1725
We report a facile approach to fabrication and characterization of cationic titanium dioxide (TiO2+) on poly (vinyl alcohol)/poly (acrylic acid) (PVA/PAA) composite electro-spun nanofibrous mat. The aim of this study is to develop a “functional electrospun nanofibrous mat” as a sustainable approach to superior photocatalytic degradation of organic colorants. For that, the PVA/PAA nanofibrous mat was prepared by electrospinning of PVA and PAA solution according to an aspect ratio of 1:1 and later water stability was induced by the thermal cross linking at an elevated temperature of 145 °C for 30 minute. By means of electrostatic layer-by-layer (LbL) assembly, cationic titanium dioxide (TiO2+, ~19 nm) was immobilized on the surface of the water stable nanofibrous mat. As functionalized composited nanofibrous mat was characterized by using scanning electron microscope (SEM), fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) analysis and thermogravimetric analysis (TGA). Superior competency of the functionalized nanofibrous mat towards photocatalytic degradation of organic dye (methyl blue) in aqueous solution was observed by using UV-visible spectrophotometer with quantitative measuring method. The result indicates a complete degradation of methyl blue within 40 mins and superior reusability upto 5 cycles application. The study signifies the prospect of using electrospun nanofibers to manipulate the catalytic activity, which could be a foundation for further rational design of various composite nanofibrous materials. 相似文献
54.
Fawzia S. Al‐Yousif Mohammed H. Al‐Whaibi Sayeda O. El‐Hirweris 《Journal of plant nutrition》2013,36(6):1037-1052
Date palm (Phoenix dactylifera L. cv Khedhri) and sorghum (sorghum Sudan grass hybrid cv sugar Graze 11) plants were grown in vermiculite in a controlled environment and watered with a nutrient solution containing eight different concentrations of boron (B) (0 to 500 ppm), six months for date palm and four weeks for sorghum. The chlorophyll (Chl) content of the seedlings increased significantly with low concentrations of B for both date palm and sorghum, but no further significant increases were observed at higher concentrations. Generally, there was a positive correlation between B and calcium (Ca) content in the tissues of both seedlings when B concentrations were increased in the media. A negative correlation was found between B concentration in the media and the tissue content of phenolic compounds and the activity of some enzymes, such as polyphenol oxidase, IAA‐oxidase and phenylalanine ammonia‐lyase in the tissue, while there was a positive correlation in the case of peroxidase. Ribonucleic acid (RNA) increased significantly in date palm with the increase of B in the medium, but for sorghum, the increase occurred at 10–100 ppm and decreased at 300 and 500 ppm B in the media. 相似文献
55.
56.
We determined the effects of petroleum spray oil (PSO) (Caltex Canopy®) on oviposition responses of Helicoverpa armigera Hubner and Ostrinia nubilalis Hubner adults, and larval survival of the pest moths on cotton and maize plants in the laboratory. Application of 2% (v/v) of the PSO deterred H. armigera oviposition. Increasing the rate from 2 to 5% (v/v) did not significantly reduce the number of eggs laid by H. armigera on the treated plants. In contrast, the minimum rate at which the oil could deter oviposition of O. nubilalis on maize plants was 5% (v/v). Increasing the rate from 5 to 10% (v/v) did not significantly reduce the number of eggs laid per plant. However, a reduction in the rate of the PSO from 5 to 3% (v/v) resulted in a 73.9% increase in oviposition activity on the maize plants. In wind tunnel bioassay tests, all mated H. armigera females tested could detect and settle on plants treated with water but with plants treated with PSO at various times, only 50% of tested females settled on the plants 4?–?5 days after treatment (DAT) and none on the plants 0?–?2 DAT. A solid phase micro-extraction (SPME) test to determine the effect of the PSO on volatiles released by the cotton plants showed that the quantity of volatiles released by the cotton plants treated with PSO was lower than for water treated plants. This indicates that the PSO sprays may be suppressing or masking the leaf surface volatiles of the cotton plants, thereby deterring oviposition of H. armigera. Larval survival data show that PSO sprays can cause direct mortality of first, second and third instar O. nubilalis larvae. PSOs may have the potential to be integrated into pest management programme targeting H. armigera and O. nubilalis on cotton and maize crops, respectively. 相似文献
57.
58.
M. A. A. Mamun S. Nasren K. H. Srinivasa S. S. Rathore P. B. Abhiman K. Rakesh 《Journal Of Applied Aquaculture》2020,32(1):81-93
ABSTRACTStriped catfish (Pangasianodon hypophthalmus) fingerlings were stocked (60 fishes/m3) in cemented square tanks for ornamental fishery purposes at the College Fish Farm in Mangalore. A total of 400 fishes with a mean weight (g) ranging from 3.24 ± 1.21 to 6.70 ± 1.13 and a mean length (cm) of 7.50 ± 0.94 to 9.50 ± 1.10 were examined. A severe outbreak of salt-like granule white spots was found on the body surface. Ichthyophthirius multifiliis, a ciliate pathogen, was identified as the causative agent by clinical signs, wet mount, and histopathological observations. Infected fishes were transferred and equally distributed to the 0.45 m3 glass aquaria and treated with three treatments: (T1) methylene blue + salt; (T2) raising temperature with salt; and (T3) formalin + malachite green. The best fingerling survival (55 ± 9.36%) was obtained by elevated water temperature with salt in T2. 相似文献
59.
The efficacy of four chemical reagents, iodophor, formalin, hydrogen peroxide and bronopol as fish egg surface disinfectants were evaluated in bluefin sea bream (Sparidentex hasta). Fertilized eggs were counted and subjected to a static bath dip treatment in different concentrations of the above chemicals for 4 min before being incubated at 20 ± 0.5°C for 40 h. Treatment efficacy of the different disinfectants was evaluated by assessing the bactericidal activity, egg hatch percentage and survival of larvae up to 3 days post hatch. Results showed that iodophor at medium concentrations (75 and 100 ppm) was the best of all tested disinfectants in bacterial killing ability (12% reduction in the bacterial counts), egg hatching per cent (99.8% and 99.6% respectively) and larval survival up to 3 days post hatch (50.8% and 54.8% respectively). Formalin was the second best disinfectant at levels of 100 and 150 ppm. Hydrogen peroxide gave good results compared with the control while, bronopol showed discouraging results. In conclusion, iodophor appeared to be suitable for bluefin sea bream eggs disinfection with a 4 min exposure to 75–100 ppm when applied 14–16 h after egg fertilization. 相似文献
60.
H. M. S. Al Ubeed M. C. Bowyer J.B. Golding 《The Journal of Horticultural Science and Biotechnology》2019,94(5):620-626
Hydrogen sulphide (H2S) inhibits senescence in harvested fruit and vegetables but presents logistical, safety and regulatory issues to become a commercial treatment. D-cysteine and L-cysteine are semi-essential amino acids that are metabolised to hydrogen sulphide by plant tissues albeit by different pathways. This paper examines the effect of cysteine on postharvest senescence of three green leafy vegetables. Spraying pak choy leaves with 10 mmol D-cysteine, L-cysteine or DL-cysteine inhibited leaf senescence through a delayed loss of green colour expressed as market life, reduced respiration rate and reduced ethylene production. The beneficial effects of cysteine were similar to those achieved by fumigation with hydrogen sulphide. L-cysteine sprays on parsley and peppermint leaves also showed reduced leaf colour loss and respiration compared to untreated leaves. Cysteine, either as the racemate or individual enantiomers, is considered to have commercial potential for green leafy vegetables as it provides the beneficial effect of hydrogen sulphide but should be easier to register for commercial use due to the GRAS status of L-cysteine. 相似文献