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51.
52.
利用灰色系统理论的预测和决策功能,对粮食产量进行统计和预测。结果表明:用GM(1,1)模型对粮食产量预测,建模简单,预测精度高,在预测粮食产量、气候变化、农田灾害等方面有较大的实用意义。 相似文献
53.
Anjorin Godwin Ajiboye Adeleke Joseph Ogunwale 《Archives of Agronomy and Soil Science》2013,59(2):247-258
The potassium status of soils developed over talc overburden in a southern Guinea savanna of Nigeria was evaluated using exchangeable, acid extractable, total and residual potassium values in particle-size fractions. Soil samples collected from genetic horizons of six profile pits at Kampe Forest Reserve were separated into sand, silt and clay fractions. Exchangeable K, acid-extractable K, total K and residual K were determined in these fractions. Reserved K values were similar to those of mobile K, but lower than total and residual K, whereas exchangeable K showed the lowest values. Total K was >25 cmol kg?1 in all the profiles; reserved K ranged from 9.26 to 24.45 cmol kg?1 and mobile K ranged from 5.12 to 29.57 cmol kg?1. Exchangeable K accounted for <1% of total K and ranged from 0.20 to 0.50 cmol kg?1. In most cases, the clay fraction of the soils had the highest values for all potassium forms, followed by the silt fraction, while the sand fraction had the lowest values for these forms of potassium. 相似文献
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植被净初级生产力(NPP)可以反映植被生长状况,是表征地区生态质量的重要指标。本文以滦河流域为研究区,调查采集植被NPP、气象、土地利用结构及变化等多时空数据,利用Sen趋势、Hurst指数及残差分析等多种方法,综合考虑自然环境和人为利用的影响,对2000—2015年植被NPP的时空变化特征、未来演变趋势及驱动因子进行分析和研究,并定量识别不同区域内的主导驱动因子,旨在为该流域的生态环境治理工作提供依据。研究结果表明:1)2000—2015年,滦河流域植被NPP年均值为455.04g(C)·m~(-2)·a~(-1),整体呈波动上升趋势,显著增加区占流域总面积的32.94%,且未来同向变化趋势略强于反向变化趋势;2)该流域植被NPP空间差异较为显著,表现为东南高西北低的格局,受地形影响较大,流域中游的低山丘陵区为植被NPP高值区;3)驱动机制上,流域植被NPP变化与温度和降水均为正相关关系,水热耦合共同作用于植被NPP的积累,人类活动则是通过改变土地利用强度或生态建设工程等影响植被NPP的变化,且在不同地形区域内,植被NPP变化的主导驱动因子不同,整体上以气候和人类活动共同正向促进作用为主,但在平原区以单因子的反向抑制作用为主。 相似文献
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The analysis of saltwater intrusion through Komesu underground dam and water quality management for salinity 总被引:2,自引:1,他引:1
The Komesu underground dam is the first full-scale underground dam constructed to prevent saltwater intrusion in Japan. Although
the cutoff wall of the dam effectively reduces the movement of saltwater into the reservoir area, saltwater masses remained
behind the dam at the time of its completion, and saltwater can intrude beneath and diffuse through the wall, particularly
when the reservoir level is below the sea level because of high pumping levels during the drought years. Therefore, it is
necessary to estimate in advance whether the saltwater concentration in the pumped water is likely to exceed or not the permissible
salinity level because of an increase in the residual saltwater mass as a result of saltwater intrusion and to take necessary
measures to suitably manage the saltwater level behind the dam. To analyze saltwater intrusion, we first selected the optimal
program suitable for the analysis of saltwater intrusion. Second, we examined the longitudinal dispersivity and the effect
of the cone of depression around the pumping wells. Then we analyzed saltwater intrusion into the reservoir area in detail
by using a two-dimensional convective–dispersive analysis. The results of the analysis make it possible to improve management
of saltwater in the reservoir area behind the underground dam. 相似文献
58.
Validating a segment on the short arm of chromosome 6 responsible for genetic variation in the hull silicon content and yield traits of rice 总被引:2,自引:0,他引:2
Wei-Min Dai Ke-Qin Zhang Ji-Rong Wu Lei Wang Bin-Wu Duan Kang-Le Zheng Run Cai Jie-Yun Zhuang 《Euphytica》2008,160(3):317-324
Rice is a typical silicon-accumulating plant and the beneficial effect of silicon on rice has long been recognized. In a previous
study using 244 recombinant inbred lines (RILs) of an indica rice cross, Zhenshan 97B/Milyang 46 grown in 2003, four QTLs
were detected for hull silicon content. QTL qHUS-6 had the largest effect among these, and the same interval also had significant effects on yield traits in the same population.
The primary objective of this study was to validate the QTL effect in this region on HUS and yield traits. The same RIL population
and another RIL population of lower heterogeneity were grown in 2004. QTL qHUS-6 was found to have significant additive effects on hull silicon content with a consistent direction in the two populations.
From a residual heterozygous line selected from RILs of the same cross, 15 F2:3 lines that differed only in a 2.15-Mb segment extending from RM587 to RM6119 on the short arm of chromosome 6 were derived.
In these lines, qHUS-6 displayed a major effect, so did QTLs for yield traits previously detected in the same region. Two more QTLs for HUS detected
in 2003, qHUS-1-1 and qHUS-1-2, also had consistent effects in the Zhenshan 97B/Milyang 46 RIL population in 2004. Thus this study verified three candidate
regions for fine mapping HUS QTLs and determining the genetic relationship between silicon content and yield traits in rice. 相似文献
59.
由于黄泛区平原水库坝基一般为软弱透水地基,坝基经过防渗处理后,坝基渗透稳定,渗漏量得到有效控制,但坝基不可避免的还有一定数量的渗漏量,下游坝址外尚保留一定的剩余水头,渗水如果不及时排走,会导致区域地下水位升高,造成库外农田浸没。笔者以山东聊城发电厂新厂引黄调蓄水库为依托,阐述平原水库如何用排渗沟和减压井联合排渗减压技术防止库外浸没和土地盐碱化。减压井和排渗沟联合排渗减压是降低地下水位、防止库外浸没的有效措施。 相似文献
60.