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71.
Thinh Tuan Chu John W.M. Bastiaansen Elise Norberg Peer Berg 《Acta Agriculturae Scandinavica, Section A - Animal Sciences》2018,68(1):1-10
To improve genetic gain of breeding programs for village poultry production, breeding schemes with observations obtained in village production systems using individual (VIO) and group recording (VGO) were examined under different levels of genotype-by-environment-interactions (GxE). GxE was modeled by varying the correlation between traits measured in the breeding station and village environments for bodyweight (rg_BW) and egg production (rg_EP). Relative and absolute genetic gains obtained from VIO and VGO were used for comparison between the schemes. Results showed that village observations significantly improved genetic gains compared to the scheme without birds tested in the village. The improvement was only slightly larger with individual observations than with group observations. Higher rg_BW and rg_EP led to lower relative genetic gain, but a higher absolute gain of VIO and VGO. It is recommended to apply a breeding scheme using group recording of village performance when strong GxE in breeding for village poultry is expected. 相似文献
72.
山地丘陵区不同土地利用方式对空心村整治还田土壤团聚体特征的影响 总被引:2,自引:0,他引:2
以探明不同土地利用方式对土壤团聚体的影响为目的,为提高山地丘陵区空心村整治还田土壤稳定性及生产性能提供科学依据。在陕西澄县山地丘陵区空心村整治还田后,设置5种不同的土地利用方式,开展为期1年的种植试验,分别为玉米(C处理)、小麦(W处理)、蔬菜(V处理)、药材(M处理)及对照(未种:CK处理)。测定分析干筛法和湿筛法0—40cm土层土壤团聚体分布、平均质量直径(WMD)、几何平均直径(GMD)、团聚体破坏率(PAD)、不稳定团粒数(ELT)和分形维数(D)。结果表明:(1)各处理在0—40cm各土层土壤团聚体数量及大小均显著优于CK处理,各处理干筛下0—40cm土层0.25mm团聚体含量(DR0.25)和湿筛下该含量(WR0.25)随着土壤土层深度的增加呈现相反的趋势;(2)干筛法和湿筛法0—40cm土层各处理土壤平均重量直径(MWD)平均值和几何平均直径(GMD)平均值大小顺序均呈现W处理C处理M处理V处理CK处理,C处理有助于增加表层土壤大团聚体含量,W处理则有助于增加下层土壤大团聚体含量;(3)湿筛法分析表明,各处理土壤团聚体破坏率(PAD)和不稳定团粒指数(ELT)在0—40cm土层内均表现出近似"Z"字形趋势,各处理显著低于CK;(4)各处理的分形维数(D)在0—40cm土层平均值大小顺序为C处理W处理M处理V处理CK处理。土壤分形维数(D)与干筛法和湿筛法下0—40cm土层0.25mm团聚体含量之间存在良好的线性关系,分别为R2=0.74和R2=0.67。空心村整治还田后种植玉米和小麦有利于提高0—40cm土层大团聚体含量,增加土层稳定性,改善土壤结构。 相似文献
73.
The expansion of the Shanghai metropolitan region has caused a substantial amount of farmland to become urbanized. Most farmers have lost their land and have been relocated from villages to new collective settlements, resulting in dramatic changes in the landscape pattern. This study explores the effects of this transformation on the spatiotemporal dynamics of plant diversity. We randomly sampled 22 plots comprising 294 subplots within two crossed transects that pass through 5 traditional villages and 17 new settlements. The results show that resettlement has exerted significant effects on plant species diversity, both temporally and spatially. Temporally, the Gleason index (GI) of total species over time could be ordered as 1990s > 2000s > 1980s, while Shannon’s diversity index (SHDI) was ordered as 2000s > 1990s > 1980s. Spatially, the GI of total species decreased from the urban center to the exurbs or from the inside to the outside of the built-up areas. SHDI was highest in suburbs or ecotones. Furthermore, the GI of total species had significant correlations with those of indigenous species, exotic species, and planted species (r > 0.90, p < 0.01) as well as with the region and location of settlement (r < −0.48, p < 0.01). Both indigenous and exotic species had significant positive correlations with total species richness at 0.01 levels. Generally, compared with traditional settlements, new settlements displayed greater richness and diversity of plant species, primarily because of the exotic species present in new settlements. The farmers’ socio-economic status was found to be the primary cause of differences in species richness. To protect indigenous and wild species, it is necessary to take into account local knowledge in villages to encourage Chinese farmers to participate actively in community greening. A bridge should be built between traditional villages and modern settlements and between the past and future for farmers. 相似文献
74.
75.
Helmut Brandl 《Small-Scale Forestry》2006,5(1):145-159
Today the Black Forest is an internationally renowned tourist region in Germany. For centuries the Black Forest remained as
a low mountain range regarded as not suitable for settlement due to its unfavourable climatic conditions and difficult terrain.
Clearing the dense forests and settlement therefore started at a historically late stage compared to other regions of Germany,
about 1000 years ago. Due to the special conditions in this area, the structure of the settlement had to be quite different
to those landscapes with more favourable conditions for agriculture. A single-farm settlement developed, farms situated 200
to 400 m away from each other, surrounded by meadows, agricultural land and forests and owned by the farmer’s family. This
structure has remained in some areas until today; in other areas different types of settlement took place, and great changes
occurred during history. A special type of agroforestry — a slash-and-burn-management of forests — also took place 150 to
200 years ago. 相似文献
76.
介绍了楠溪江流域岩头村丽水街、苍坡村及林坑村3个典型古乡村园林的历史由来和建筑格局,指出其具有拙朴自然、功能实用、公共性强等特点,并与私家园林和皇家园林作了比较,进一步提出楠溪江古乡村园林所具有的价值和现代意义。提出了建立以村民为中心的保护机制、以旅游开发促保护和实施政策倾斜的保护机制的建议。 相似文献
77.
通过对林业生态建设的必要性、在实施过程中采取的措施和农村经济发展状况等方面的探讨,阐述了沿海地区林业生态建设与农村经济发展的关系,提出了社会经济可持续发展的途径。 相似文献
78.
79.
农业生产托管模式效率差异及其影响因素研究——以黑龙江省为例 总被引:1,自引:0,他引:1
农业生产托管是实现小农户与现代农业有机衔接的重要途径,但不同托管模式可能存在效率差异,探究不同托管模式的效率差异对农业现代化发展具有重要的现实意义。本文基于产权理论,以黑龙江省为例,利用农业生产托管组织的调查数据,运用超越对数随机前沿生产函数,分析不同农业生产托管模式的技术效率差异并探讨其影响因素。结果表明,农业生产托管分为村集体主导型和新型农业经营主体主导型两种模式,村集体主导模式与新型农业经营主体主导模式之间存在技术效率差异,村集体主导模式的平均技术效率比新型农业经营主体主导模式高7.79个百分点。农业生产托管规模、托管土地细碎化程度、托管组织自给劳动力人数、设置农业经纪人能显著影响农业生产托管的技术效率。村集体主导模式与新型农业经营主体主导模式效率差异原因在于村集体主导模式土地细碎化程度较低,且由于产权原因自给劳动力人数普遍较多,而新型农业经营主体主导模式没有充分发挥托管规模与农业经纪人优势。因此,提出积极鼓励发展村集体主导模式、进一步支持新型农业经营主体扩大托管规模、培育农业经纪人队伍等建议。 相似文献
80.
选取具有代表性的洪湖市南昌村作为“以奖促治”典型村开展了农村环境监测,结果表明:该村环境空气质量达到国家二级标准,地表水富营养化污染严重,地下水不适合直接饮用,土壤中农药残留超标。通过典型案例研究,对典型地区农村空气、水、土壤等环境要素的污染源与危害现状进行了调查研究,提出了农村环境监测优化布点方法和监测指标,以及农村环境质量评价的技术方法。 相似文献