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排序方式: 共有258条查询结果,搜索用时 31 毫秒
1.
针对现阶段水稻秧盘育秧技术中制匀泥浆效率低下的问题,采用正交设计方法、计算流体动力学数值模拟和试验分析,对不同参数刀片在水田中匀浆作业时的匀浆效果和功率损耗进行研究。结果表明:1)单刀切削幅宽为影响泥浆运动速度和功率损耗的最大因素,折弯角影响不明显;2)当刀片滑切角为50°,折弯角为115°,单刀切削幅宽为60 mm时,刀片匀浆效果好;当滑切角为30°,折弯角为135°,单刀切削幅宽为20 mm时,功率损耗小;3)刀片中心面处和刀片折弯侧0.1 m处刀片打匀泥浆效果良好;4)功率损耗仿真值与试验值平均相对误差为12.16%,在可接受范围内。 相似文献
2.
为探明毯苗插秧机增加取秧块面积的改进技术以及在该技术下稀播长秧龄的水稻适宜播量、秧龄和育秧盘,并形成毯苗机插稻稀播长秧龄农机与农艺相配套技术。结果表明,经过对毯苗插秧机性能的改进,增大取秧面积,毯苗机插杂交稻可实现与钵苗机插稻相当的产量,同时常规稻产量比未改进的常规毯苗机插稻增产4.74%~6.83%;机插水稻秧龄在30 d内,秧龄和产量成正相关关系,播量80 g/盘、秧龄30 d的处理产量最高;与普通塑料盘相比,大体钵型毯状降解盘透水透气性好,栽插带土成球,秧苗素质好,植伤轻,水稻缓苗期短。 相似文献
3.
为了研究保水剂对育秧过程中水稻秧苗素质和生理特征的影响,进行了育秧盘中添加5~30g/盘交联聚丙烯酰胺保水剂的育秧试验。结果表明:与不添加保水剂(对照)相比,添加保水剂后秧苗的株高、叶龄、叶长、叶宽、叶鞘长有所提高,其中叶宽与对照相比差异均达显著水平;20 g/盘处理与对照相比,叶龄、最长根长、假茎宽、百株鲜质量等差异显著;15 g/盘处理秧苗百株鲜质量和干质量分别为18.56 g和2.71 g,与对照相比达显著水平。15 g/盘处理秧苗的叶绿素含量、根系活力、SOD活性分别为9.35 mg/g、4.60μg/(g·h)、129.18 U/g,为所有处理的最大值;CAT活性在5~15 g/盘处理时变化不大,超过这一范围则下降。MDA含量在保水剂添加量15 g/盘以下时变化不明显,超过20 g/盘后明显上升。育秧盘中添加15~20 g/盘保水剂可提高秧苗叶绿素含量,使秧苗SOD等功能酶处于较佳的生理状态,提高水稻根系活力,促进地下部的生长,从而提高水稻盘育秧秧苗素质。 相似文献
4.
穴盘育苗是苔草繁育的重要技术环节。为加快苔草的繁育速度,采用不同规格穴盘播种以研究青绿苔草(Carex breviculmis)、涝峪苔草(C.giraldiana)、披针苔草(C.lanceolata)、矮丛苔草(C.humilis var.nana)、脚苔草(C.pediformis)的适宜播种穴盘孔数对5种苔草出苗和幼苗生长的影响。通过对各种苔草的开始发芽时间、持续发芽时间、发芽率和幼苗的株高、叶数、单株鲜重等生长指标的分析,结果表明,6月温室穴盘播种育苗,青绿苔草、涝峪苔草穴盘育苗128孔或105孔穴盘较为适宜;披针苔草穴盘育苗宜采用105孔穴盘;矮丛苔草、脚苔草穴盘育苗较适宜选择288孔穴盘。 相似文献
5.
Yuan Yang Yu KuangYu Liu Wanyi Li Zhonghua JiangLiying Xiao Mingyuan Li 《Comparative immunology, microbiology and infectious diseases》2011,34(1):65-72
In order to develop a promising vaccine candidate utilizing a combined approach to induce both antibody production and T-cell activity, the DNA fragment containing MA of HCV with five conserved epitopes was synthesized. Two types of HCV vaccine candidates (the DNA type and DNA/polymers) were constructed using MA. PLA-PEG-PLA and PLGA-PEG-PLGA were synthesized and used as micelles with encapsulated plasmid pcDNA3.1(+)-MA. The preparation of copolymers, the cloning and analysis of recombinant plasmid DNA, in vitro expression, and immunogenicity in transgenic mice were evaluated in detail. The results indicated that even single immunization and oral immunization with DNA/polymers achieved satisfying immune responses in vivo tests. As biodegradable and nontoxic triblock copolymers, the novel copolymers demonstrated a great advantage, as they made long-term and single-immunizing vaccines possible; in addition, the copolymers showed a better adjuvant effect and scarcely any side effects. 相似文献
6.
Biodegradable plastic films are desirable alternatives to traditional black polyethylene plastic for use as mulches in agroecosystems. Efforts are ongoing to engineer biodegradable plastic mulches that could be incorporated into the soil at the end of the crop season, and decomposed by microorganisms, ultimately to CO2, H2O, and biomass. Whether changes in soil quality occur during or following biodegradation is unknown. An 18-month study evaluated the effects on soil quality following burial of four potentially biodegradable mulches and a no mulch control in high tunnel and open field tomato production systems across three geographically distinct locations (Knoxville, TN; Lubbock, TX; Mount Vernon, WA). The mulch treatments included: two starch-based mulches (BioAgri® Ag-Film and BioTelo Agri); one experimental 100% polylactic acid mulch (Spunbond-PLA-10); one cellulose-based mulch (WeedGuardPlus; positive control); and a negative control (no mulch). The soil management assessment framework (SMAF) was used to calculate a soil quality index (SQI) according to five dynamic soil properties: microbial biomass carbon, β-glucosidase, electrical conductivity, total organic carbon (TOC), and pH. Within the 18-month evaluation period, the effects of the biodegradable mulches on the SQI were minor, and dependent upon production system and time of incubation at all locations. In general, the SQI was higher in the high tunnel systems for some of the mulch treatments at Knoxville and Lubbock but the opposite was true at Mount Vernon. By the final sampling at 18 months, the SQI was lowest for WeedGuardPlus at Lubbock and Mount Vernon but at Knoxville, the WeedGuardPlus SQI was not significantly different from the no mulch control. Of the five SMAF indicators evaluated, soil microbial biomass and β-glucosidase activity were the most responsive to mulch and production systems, supporting the use of these variables as soil quality indicators for short-term changes due to this agricultural management practice. 相似文献
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《International Journal of Fruit Science》2013,13(1):91-105
Abstract This paper focuses on the cropping systems in central European countries such as Belgium, The Netherlands, UK, Ireland, Germany, Switzerland and the northern part of France and Italy. During the last decade there has been a consistent increase in programmed “out-of-season” strawberry production in several central European countries. This is being achieved in part, by using cultivars with different cropping seasons, but mainly by sequential planting of cold-stored plants and by growing strawberries in greenhouses and plastic tunnels. These methods have made it possible to extend the strawberry production for 11 months, from the end of February until mid January in central European countries with moderate climates. 相似文献