全文获取类型
收费全文 | 237篇 |
免费 | 24篇 |
专业分类
林业 | 12篇 |
农学 | 18篇 |
基础科学 | 2篇 |
34篇 | |
综合类 | 10篇 |
农作物 | 21篇 |
水产渔业 | 20篇 |
畜牧兽医 | 110篇 |
园艺 | 7篇 |
植物保护 | 27篇 |
出版年
2022年 | 9篇 |
2021年 | 10篇 |
2020年 | 14篇 |
2019年 | 22篇 |
2018年 | 16篇 |
2017年 | 16篇 |
2016年 | 12篇 |
2015年 | 12篇 |
2014年 | 12篇 |
2013年 | 13篇 |
2012年 | 14篇 |
2011年 | 12篇 |
2010年 | 9篇 |
2009年 | 7篇 |
2008年 | 7篇 |
2007年 | 9篇 |
2006年 | 6篇 |
2005年 | 4篇 |
2004年 | 5篇 |
2003年 | 1篇 |
2002年 | 3篇 |
2001年 | 5篇 |
2000年 | 4篇 |
1999年 | 1篇 |
1998年 | 2篇 |
1997年 | 3篇 |
1996年 | 3篇 |
1995年 | 1篇 |
1994年 | 3篇 |
1993年 | 6篇 |
1992年 | 5篇 |
1991年 | 1篇 |
1990年 | 3篇 |
1989年 | 1篇 |
1988年 | 2篇 |
1985年 | 4篇 |
1982年 | 1篇 |
1981年 | 1篇 |
1978年 | 1篇 |
1977年 | 1篇 |
排序方式: 共有261条查询结果,搜索用时 0 毫秒
31.
Loss of seeds from mature pods is common in Vicia sativa L., an important annual, resown forage legume in West Asia and North Africa. Pod shattering restricts its use as a leguminous forage crop. This paper reports the results of germplasm evaluation for non-shattering pods and of breeding and selection to improve seed retention. Wide variation in pod-shattering exists between common vetch ecotypes collected from different regions. Three wild mutants with almost completely non-shattering pods were identified and isolated for use as a genetic resource in cross breeding programmes. Genetic studies revealed that the non-shattering character in the wild types of common vetch is due to a simple recessive gene, whereas shattering in the cultivated types is due to an allelic dominant pair of genes. Incorporation of the non-shattering gene into agronomically-promising lines was achieved by back-crossing. Lines having an average of 95—97 % non-shattering pods were obtained, as compared to 40—50 % in the original cultivated lines which represents a major agronomic advance in common vetch breeding. The importance of seed retention to the economics of seed production is discussed. 相似文献
32.
The major limiting factor to livestock production in West Asia and North Africa is the inadequate feed supply. The introduction of leguminous forage species into fallow lands represents a means of increasing feed supplies for the rapidly growing livestock population.
Twenty five lines each of common vetch ( Vicia sativa L.) wooly-pod vetch ( Vicia villosa ssp. dasycarpa Ten.), and bitter vetch ( Vicia ervilia L.) were tested over three seasons with contrasting rainfalls and winter temperatures. For each species, seedling vigour, winter growth, cold effect, spring growth, leafiness, herbage yield at 100 % flowering, grain yield, harvest index and aspects of herbage quality were recorded. There were considerable variation among entries with the same species, entries of V. ervilia were the earlier in flowering and maturity, and V. villosa ssp. dasycarpa almost the latest by 45 days. V. sativa , was the most affected by frost whilst both V. villosa ssp. dasycarpa and V. ervilia proved to be cold tolerant.
Although V. villosa ssp. dasycarpa produced high herbage yield in springs its grain yield is low resulting in a low harvest index. Both V. ervilia and V. sativa produced high grain yield with high harvest index. Seed yield was negatively correlated (P < 0.01) with days to flowering and maturity indicating the need of earlier types.
Quality of the herbage in term of digestibility was far lower (46 % IVDMD) in V. villosa ssp. dasycarpa than the other two species (69 % and 72 %).
The possible niches and utilization of each species as animal feed in the prevailing farming systems are discussed. 相似文献
Twenty five lines each of common vetch ( Vicia sativa L.) wooly-pod vetch ( Vicia villosa ssp. dasycarpa Ten.), and bitter vetch ( Vicia ervilia L.) were tested over three seasons with contrasting rainfalls and winter temperatures. For each species, seedling vigour, winter growth, cold effect, spring growth, leafiness, herbage yield at 100 % flowering, grain yield, harvest index and aspects of herbage quality were recorded. There were considerable variation among entries with the same species, entries of V. ervilia were the earlier in flowering and maturity, and V. villosa ssp. dasycarpa almost the latest by 45 days. V. sativa , was the most affected by frost whilst both V. villosa ssp. dasycarpa and V. ervilia proved to be cold tolerant.
Although V. villosa ssp. dasycarpa produced high herbage yield in springs its grain yield is low resulting in a low harvest index. Both V. ervilia and V. sativa produced high grain yield with high harvest index. Seed yield was negatively correlated (P < 0.01) with days to flowering and maturity indicating the need of earlier types.
Quality of the herbage in term of digestibility was far lower (46 % IVDMD) in V. villosa ssp. dasycarpa than the other two species (69 % and 72 %).
The possible niches and utilization of each species as animal feed in the prevailing farming systems are discussed. 相似文献
33.
Metwally Abd El-Alim A. Safina Sayed A. Abdel-Wahab Eman I. Abdel-Wahab Sherif I. Abdel-Wahab Tamer I. 《Journal of Crop Science and Biotechnology》2021,24(2):203-220
Journal of Crop Science and Biotechnology - Cropping systems are relatively more important for testing soybean genotypes under Egyptian conditions. A field experiment was carried out at the... 相似文献
34.
Irrigation rate and plant density effects on yield and water use efficiency of drip-irrigated corn 总被引:3,自引:0,他引:3
Salah E. El-Hendawy Essam A. Abd El-Lattief Mohamed S. Ahmed Urs Schmidhalter 《Agricultural Water Management》2008,95(7):836-844
The efficient use of water by modern irrigation systems is becoming increasingly important in arid and semi-arid regions with limited water resources. This study was conducted for 2 years (2005 and 2006) to establish optimal irrigation rates and plant population densities for corn (Zea mays L.) in sandy soils using drip irrigation system. The study aimed at achieving high yield and efficient irrigation water use (IWUE) simultaneously. A field experiment was conducted using a randomized complete block split plot design with three drip irrigation rates (I1: 1.00, I2: 0.80, and I3: 0.60 of the estimated evapotranspiration), and three plant population densities (D1: 48,000, D2: 71,000 and D3: 95,000 plants ha−1) as the main plot and split plot, respectively. Irrigation water applied at I1, I2 and I3 were 5955, 4762 and 3572 m3 ha−1, respectively. A 3-day irrigation interval and three-way cross 310 hybrid corn were used. Results indicated that corn yield, yield components, and IWUE increased with increasing irrigation rates and decreasing plant population densities. Significant interaction effects between irrigation rate and plant population density were detected in both seasons for yield, selected yield components, and IWUE. The highest grain yield, yield components, and IWUE were found for I1D1, I1D2, or I2D1, while the lowest were found for I3D2 or I3D3. Thus, a high irrigation rate with low or medium plant population densities or a medium irrigation rate with a low plant population density are recommended for drip-irrigated corn in sandy soil. Crop production functions with respect to irrigation rates, determined for grain yield and different yield components, enable the results from this study to be extrapolated to similar agro-climatic conditions. 相似文献
35.
New strategies to enhance growth and productivity of food crops in saline soils represent important research priorities. This study has investigated the role of certain priming techniques to induce salt tolerance of bread wheat. Wheat grains were soaked in 0.2 mm sodium nitroprusside as nitric oxide donor (redox priming), diluted sea water (halopriming) and the combination of both (redox halopriming). Grains were also soaked in distilled water (hydropriming); in addition, untreated grains were taken as control. Our results indicated that priming treatments significantly improved all growth traits and increased leaf pigments concentration as compared to the control. Priming treatments markedly enhanced membrane stability index, proline, total soluble sugars and K+ concentration with simultaneous decrease in the concentration of Na+ and malondialdehyde (MDA). Furthermore, yield and yield‐related traits such as plant height, spike length, total number of tillers, 1000‐grain weight, straw and grain yield considerably affected by priming treatments. Moreover, the grain yield of both genotypes was positively affected by redox halopriming treatment. However, the extent of enhancement was more prominent in Gemmiza‐9 (salt sensitive) than that in Sakha‐93 (salt‐tolerant). Overall, this study clearly indicated that redox halopriming treatment is a promising and handy technique to induce salinity tolerance of wheat genotypes. 相似文献
36.
Evaluation of plant species for animal feed requires the quantitative and qualitative comparison of different genotypes. Promising lines of annual legumes comprising seven genotypes of vetche ( Vicia spp.) and chicklings ( Lathyrus spp.) were compared for herbage quality. The content of crude protein (CP), neutral detergent fiber (NDF) and acid detergent fiber (ADF) in herbage and pods were measured at different stages of plant maturity. The proportion of the leaves to shoots (leafiness) and in vitro dry matter digestibility (IVDMD) were also determined. As plants matured IVDMD, CP and leafiness decreased and NDF and ADF increased. For all the genotypes maximum digestible dry matter (DDM) and CP yields were more or less attained at 50–100 % podding. Narbon vetch had the highest DDM. The possible uses of the different genotypes as animal feed are discussed based on the partitioning of the DDM and CP yield as plants matured. 相似文献
37.
ABSTRACTProper irrigation timing can minimize the negative impacts that reduce crop yields. Therefore, in an initial pot experimental study, we assessed the SPAD (Soil–Plant Analysis Development)-chlorophyll meter as a tool to determine proper irrigation timing of wheat under different soil water deficit conditions in a controlled-environment greenhouse. The treatments were controlled irrigation at 100% (T1), 70% (T2), 50% (T3) and 30% (T4) of soil water content at field capacity; and the growth stages were development, mid-season and late-season. SPAD readings were measured pre-irrigation events. The results indicated that the T3 and T2 achieved maximum grain yield per accumulated crop evapotranspiration, i.e. water productivity (0.82 and 0.76 kg m?3), and were at par with T1. Moreover, the SPAD readings had a high Pearson’s correlation coefficient with crop evapotranspiration (r = 0.95; P ≤ 0.001) and wheat grain yield (r = 0.90; P ≤ 0.001), indicating that SPAD reading could be used to reliably estimate when to irrigate wheat. Therefore, T3 and T2 SPAD readings were averaged to estimate a target limit at which irrigation should be applied. Accordingly, the target limit was defined as >44.76 for the development stage, >50.72 for the mid-season stage, and >37.64 for the late-season stage; readings below this target limit indicate that it is time to irrigate. 相似文献
38.
39.
Regmi NL Abd El-Aty AM Kuroha M Nakamura M Shimoda M 《Journal of veterinary pharmacology and therapeutics》2005,28(6):553-557
We examined inhibitory effects of ofloxacin (OFX), orbifloxacin (OBFX), ciprofloxacin (CFX), enrofloxacin (EFX) and norfloxacin (NFX) on cytochrome P-450 1A (CYP1A) activities using hepatic microsomes from four beagle dogs. Ethoxyresorufin O-de-ethylation was referred as CYP1A activities. All the fluoroquinolones inhibited the reaction in a noncompetitive manner. The determined inhibitory constants were the followings; 10.1 +/- 3.8 mM for OFX, 6.43 +/- 2.01 mM for OBFX, 0.726 +/- 0.134 mM for CFX, 4.06 +/- 1.19 mM for EFX and 4.75 +/- 1.63 mM for NFX respectively. As these values are >100-fold of plasma concentrations after a clinical single dose of the fluoroquinolones, it is suggested that the inhibitory effect on CYP1A activities is not so high to elicit drug-drug interaction with CYP1A substrates, when these fluoroquinolones are co-administered. Mechanism based inhibition was also examined in this study. Of the five fluoroquinolones examined, OFX, OBFX and CFX had this inhibition manner. As this inhibition is irreversible, inhibitory effects of the three fluoroquinolones may accumulate, when they are repeatedly administered. Therefore, OFX, OBFX and CFX may result in substantial drug-drug interaction with a CYP1A substrate even in clinical states. As EFX is metabolized to CFX in the body, it may also have the same possibility. 相似文献
40.
Saieda S. Abd El-Rahman Mohamed M. Mazen Heba I. Mohamed Neven M. Mahmoud 《European journal of plant pathology / European Foundation for Plant Pathology》2012,134(1):105-116
Two different biotic inducers [Pseudomonas fluorescens and Pseudomonas putida] and three different abiotic inducers [copper sulphate, indole butyric acid and potassium chloride] were tested for their efficacy in inducing resistance in lupin plants against Fusarium wilt disease caused by Fusarium oxysporum f. sp. lupini. Application of the biotic and abiotic inducers as seed treatments significantly reduced wilt disease incidence under greenhouse and field conditions. Potassium chloride and Pseudomonas fluorescens were superior. A time course of defence-related enzymes showed substantial increases in enzyme activities in induced infected seedlings compared with untreated healthy plants or infected controls. However, the magnitude of the increase varied among treatments. The maximum increases in chitinase and ??- glucanase activities were recorded at 12 and 8?days after inoculation with the pathogen, respectively. Also, the activity of phenylalanine ammonia lyase increased dramatically 8?days after inoculation. Greater accumulation of phenolic compounds and specific flavonoids upon infection with the pathogen was found in induced and/ or infected seedlings compared with healthy plants. In addition to inducing disease resistance, the treatments were accompanied by significant increases in crop parameters and seed yield compared with untreated controls. 相似文献