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22.
为了解宁夏灌区玉米平播密植模式下田间蛾类昆虫的组成及发生时序动态,对灌区玉米田进行灯诱监测,获得蛾类昆虫标本10科42种。明确了该种植模式下蛾类以夜蛾科(Noctuidae)和草螟科(Crambidae)昆虫为主要类群,优势种为旋幽夜蛾(Discestra trifolii)、草地螟(Loxostege sticticalis)、亚洲玉米螟(Ostrinia furnacalis)和小地老虎(Agrotis ypsilon)。刀夜蛾(Simyra nervosa)为宁夏新记录的种类。8月下旬蛾类群落多样性水平最高,Shannon-Wiener指数、均匀度指数、丰富度指数及优势度指数依次为2.509 8、0.868 3、4.492 4、0.089 9。不同阶段蛾类群落相似性水平均很低,其中以7月上旬与7月中旬相似性水平最高,为0.526 3;相异性以6月中旬与7月上旬最高,为0.888 9。 相似文献
23.
A. Butorac I. Turi J. Butorac M. Mesi F. Bai N. Vuleti M. Berdin I. Kisi 《Journal of Agronomy and Crop Science》1999,183(4):271-285
In broadly conceived long-term experiments, tobacco was grown in monoculture and with different crop rotations. This paper presents results in terms of the yields achieved and the major yield components for the crops grown, and the proportion of particular tobacco quality classes obtained. In addition to tobacco monoculture (initially only fertilized and later also unfertilized) as the key crop, different types of crop rotations included, besides tobacco, the following crops: winter wheat, maize, soybean, oil-seed rape, and red clover. Experiments involved two 2-year and two 4-year crop rotations, and a 3-year, a 5-year, and a 6-year crop rotation. Experiments were set up on luvic semigley on multilayered Pleistocene sands. Average 10-year results suggest that there is an advantage of crop rotation over monoculture for tobacco leaf yields. The influence of different crop rotation types on yields of other crops was variable, tending towards higher values as the number of crops in rotation was increased. Values obtained for yield components should be considered from two angles: some of the values were primarily influenced by genetic factors, while others were influenced by ecological factors, including crop rotation as an overall biological buffer. With regard to quality classes (IB-III), the growing of flue-cured tobacco in crop rotation represents a great advancement relative to its growth in monoculture, even in a narrower crop rotation. 相似文献
24.
不同林地土壤微生物生物量垂直分布及相关性分析 总被引:3,自引:0,他引:3
对福建三明格氏栲自然保护区内的格氏栲天然林和格氏栲人工林、杉木人工林的土壤微生物生物量C、N及诸因素的垂直变化进行了研究.结果表明:3种森林土壤微生物生物量C、N均随土层深度的增加明显下降,其中不同林地0~10 cm土层土壤微生物生物量的差异最大,格氏栲天然林和格氏栲人工林、杉木人工林的土壤微生物生物量C分别为1.502±0.16、1.035±0.103、0.82±0.076 g/kg,生物量N为别为0.27±0.031、0.172±0.018、0.147±0.016 g/kg;该层格氏栲天然林微生物生物量C分别是格氏栲人工林、杉木人工林的1.46和1.83倍,生物量N分别是格氏栲人工林、杉木人工林的1.57和1.84倍.相关分析表明:微生物生物量与土壤pH和土壤密度呈负相关,而与全N、全P、水解N和速效P含量呈正相关;与土壤有机C、轻组有机C、颗粒有机C含量及细根生物量之间呈显著(P<0.05)或极显著(P<0.01)的相关性,与土壤可溶性有机C含量的相关性未达显著水平(P>0.05). 相似文献
25.
KIMMINS J P 《中国林业科技(英文版)》2008,(1)
Site degradation and yield decline of forest have attracted increasing attention from forest managers and scientists. Studies conducted by researchers from a variety of disciplines and perspectives have led to a variety of competing hypotheses concerning the causes of the problem. In this paper we review evidence of such a yield decline and examine the problem and its possible way to identify the individual contributions of the many determinants of yield decline, and their interactions. 相似文献
26.
不同放养和管理模式对三角帆蚌生长与养殖产量的影响 总被引:10,自引:0,他引:10
2004年7月28日-10月28日在浙江省诸暨市淡水珍珠业省级科技创新服务中心枫桥实验基地通过围隔实验研究了不同放养和管理模式对1龄和2龄三角帆蚌生长与养殖产量的影响。实验中采用三种放养模式:三角帆蚌单养,三角帆蚌与鲢、鳙混养,三角帆蚌与异育银鲫混养。每种放养模式采用施肥、施肥结合投喂鱼或蚌配合饲料两种管理措施。实验开始和结束时测量三角帆蚌壳长、蚌壳宽、蚌重和鱼体重,根据蚌、鱼成活率和生长计算产量。实验结果表明:1龄和2龄三角帆蚌生长和养殖产量因放养模式而异,鱼蚌混养不仅额外获得鱼产量,同时也提高了蚌产量。两种鱼蚌混养模式相比,混养异育银鲫对1龄三角帆蚌生长较有利,混养鲢和鳙对2龄三角帆蚌生长较有利。在施肥、施肥结合投喂鱼或蚌配合饲料两种管理措施下,三角帆蚌生长和产量无明显差异。 相似文献
27.
Ping Zhu Jun Ren Lichun Wang Xiaoping Zhang Xueming Yang Don MacTavish 《植物养料与土壤学杂志》2007,170(2):219-223
A long‐term fertilization experiment with monoculture corn (Zea mays L.) was established in 1980 on a clay‐loam soil (Black Soil in Chinese Soil Classification and Typic Halpudoll in USDA Soil Taxonomy) at Gongzhuling, Jilin Province, China. The experiment aimed to study the sustainability of grain‐corn production on this soil type with eight different nitrogen (N)‐, phosphorus (P)‐, and potassium (K)–mineral fertilizer combinations and three levels (0, 30, and 60 Mg ha–1 y–1) of farmyard manure (FYM). On average, FYM additions produced higher grain yields (7.78 and 8.03 Mg ha–1) compared to the FYM0 (no farmyard application) treatments (5.67 Mg ha–1). The application of N fertilizer (solely or in various combinations with P and K) in the FYM0 treatment resulted in substantial grain‐yield increases compared to the FYM0 control treatment (3.56 Mg ha–1). However, the use of NP or NK did not yield in any significant additional effect on the corn yield compared to the use of N alone. The treatments involving P, K, and PK fertilizers resulted in an average 24% increase in yield over the FYM0 control. Over all FYM treatments, the effect of fertilization on corn yield was NPK > NP = NK = N > PK = P > K = control. Farmyard‐manure additions for 25 y increased soil organic‐matter (SOM) content by 3.8 g kg–1 (13.6%) in the FYM1 treatments and by 7.8 g kg–1 (27.8%) in the FYM2 treatments, compared to a 3.2 g kg–1 decrease (11.4%) in the FYM0 treatments. Overall, the results suggest that mineral fertilizers can maintain high yields, but a combination of mineral fertilizers plus farmyard manure are needed to enhance soil organic‐matter levels in this soil type. 相似文献
28.
R. James Cook 《European journal of plant pathology / European Foundation for Plant Pathology》2007,119(3):255-264
In view of the inconsistent performance of single or mixtures of plant growth-promoting rhizobacteria (PGPR) strains formulated
for commercial use, and the high cost of regulatory approval for either a proprietary strain intended for disease control
or a crop plant transformed to express a disease-suppressive or other growth-promoting PGPR trait, management of resident
PGPR with the cropping system remains the most practical and affordable strategy available for use of these beneficial rhizosphere
microorganisms in agriculture. A cropping system is defined as the integration of management (agricultural) practices and
plant genotypes (species and varieties) to produce crops for particular end-uses and environmental benefits. The build-up
in response to monoculture cereals of specific genotypes of Pseudomonas fluorescens with ability to inhibit Gaeumannomyces graminis var. tritici by production of 2,4-diacetylphoroglucinol (DAPG), accounting for take-all decline in the US Pacific Northwest, illustrates
what is possible but apparently not unique globally. Other crops or cropping systems enrich for populations of the same or
other genotypes of DAPG-producing P. fluorescens or, possibly and logically, genotypes with ability to produce one or more of the five other antibiotic or antibiotic-like
substances inhibitory to other soilborne plant pathogens. In the U.S Pacific Northwest, maintenance of threshold populations
of resident PGPR inhibitory to G. graminis var. tritici is the centerpiece of an integrated system used by growers to augment take-all decline while also limiting damage caused
by pythium and rhizoctonia root rot and fusarium root and crown rot in the direct-seed (no-till) cereal-intensive cropping
systems while growing varieties of these cereals (winter and spring wheat, barley and triticale) fully susceptible to all
four root diseases. 相似文献
29.
Intensification of cropping systems in recent decades has increased their productivity but affected air, soil and water quality. These harmful environmental impacts are exacerbated in Maize Monoculture (MM) and hasten the need for solutions to overcome the trade off between crop yield and environmental impacts. In a three-year cropping systems experiment, a conventional intensive maize monoculture (MMConv), with a winter bare fallow, deep soil tillage, non-limiting irrigation was compared to three Low Input Cropping Systems (LI-CS) designed as alternatives to the conventional system. They were managed with decision-rules implemented to reach specific objectives of input reduction. The LI-CS designed with Integrated Weed Management (IWM) techniques and other sustainable cropping practices, were:(i) MMLI—an IWM Low Input MM; (ii) MMCT—a Conservation Tillage combined with cover crop MM; and (iii) Maize-MSW—an IWM maize grown in rotation with soybean and wheat. A comprehensive multi-criteria assessment was carried out to quantify the agronomic, economic, social, and environmental performances of each system. A canonical discriminant analysis of performance metrics revealed large differences between the four systems. Yields were significantly higher in MMConv (11.0 Mg ha−1) and MMLI (10.3 Mg ha−1) than in Maize-MSW (8.6 Mg ha−1) and MMCT (7.8 Mg ha−1). MMCT had the largest weed infestation (density and biomass) despite the greatest use of herbicides. The Herbicide Treatment Frequency Index (HTFI), used to indicate differences in herbicide use, revealed that the MMLI (HTFI = 1.0) and Maize-MSW (1.1) halved the herbicide use as compared to the MMConv (2.1), despite having similar weed abundance levels. The LI-CS, especially MMCT, produced high biomass winter cover crops and then less nitrogen fertilization was required as compared to MMConv. Gross margins in the MMLI (1254 € ha−1) and MMConv (1252 € ha−1) were higher than the MMCT (637 € ha−1) and Maize-MSW (928 € ha−1). MMLI and MMConv had similar labour requirements. Water drainage, pesticide leaching, energy use, and estimated greenhouse gas emissions were higher in MMConv than in the LI-CS in most years. Results from this research show good potential for the MMLI to reduce the environmental impacts of MMConv while maintaining its economic and social performance. 相似文献
30.
An experiment was conducted for 3 months in 12 experimental ponds, each of 30 m2, with a view to develop a low‐cost diet for monoculture of Macrobrachium rosenbergii in ponds. Three experimental diets (30% protein) were formulated using fish meal, meat and bone meal, mustard oilcake, sesame meal and rice bran in different combinations partially replacing fish meal by meat and bone meal and sesame meal and assigned to treatments T1, T2 and T3 respectively. A commercial golda feed (Starter‐III) was assigned to T4 (reference diet). Each treatment had three replicates. Juveniles of M. rosenbergii (2.90±0.21 g) were stocked at the rate of 40 000 ha−1. Prawns were fed three times daily at the rate of 10% and 5% of their body weight at the beginning and for the last 2 months respectively. The ponds were provided with aeration during the night using air pumps. The ranges of water quality parameters recorded in different ponds were: temperature 28.9–32.5°C, dissolved oxygen 5.1–8.1 mg L−1 and pH 6.4–7.7. The results showed that the weight gain of prawns fed diet 1 was significantly higher (P<0.05) than those fed diets 2 and 3, but was not significantly different from those fed diet 4 (reference diet). The feed conversion ratio (FCR) values of diets ranged between 2.21 and 2.96 with diets 1 and 4 showing significantly lower (P<0.05) FCR values. The survivals (%) ranged between 68% and 78% with prawns fed diets 1 and 4 showing significantly higher survival. The production of prawn ranged between 921 and 1428 kg ha−1 and diet 1 resulted in a significantly high (P<0.05) production. A simple economic analysis showed that diet 1 generated the maximum net profit of Tk 159 178 ha−1. The results of the study showed that a diet containing 20% fish meal, 10% meat and bone meal, 15% mustard oilcake, 15% sesame meal, 35% rice bran, 4% molasses and 1% vitamin–mineral premixes may be recommended to the farmers for monoculture of M. rosenbergii in ponds. 相似文献