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981.
Rodomiro Ortiz Richard Trethowan Guillermo Ortiz Ferrara Masa Iwanaga John H. Dodds Jonathan H. Crouch Jose Crossa Hans-Joachim Braun 《Euphytica》2007,157(3):365-384
The main elements of the international wheat improvement program of the Centro Internacional de Mejoramiento de Maíz y Trigo
(CIMMYT), also known as the International Maize and Wheat Improvement Center, have been shuttle breeding at two contrasting
locations in Mexico, wide adaptation, durable rust and Septoria resistances, international multisite testing, and the appropriate
use of genetic variation to enhance yield gains of subsequently produced lines. Such an approach yielded successes known collectively
as the Green Revolution. However, at the beginning of the 21st century, this “cultivar assembly line” approach needs fine
tuning to address crop needs under increasingly adopted resource conserving practices, as well as those related to nutritional
requirements of the end-users. International wheat improvement will therefore focus on the targeting of traits in respective
mega-environments, and the use of participatory methods, especially in marginal environments. The main features of this wheat
improvement strategy include the introduction of new and novel sources of genetic variation through wild species, landraces,
and, potentially, the use of transgenes for intractable traits. This variation will be combined using international shuttle
breeding, and increased breeding efficiency will be achieved through marker-aided methods, more targeted use of crop physiology,
plant genetics, biostatistics, and bioinformatics. Likewise, CIMMYT will increase its focus on the needs of end-users by emphasizing
regional efforts in participatory research and client-oriented plant breeding. 相似文献
982.
A. A. Rosielle 《Euphytica》1983,32(1):49-56
Summary Computer simulation techniques were used to examine the effect of variation of genetic variance and correlation between mean and genetic variance on the efficiency of bulk yield testing procedures. Assessment of the effect of variation in various parameters was made by comparing genetic gains with the maximum potential gain. The maximum potential gain was defined as that which would be achieved if the particular bulk which maximizes genetic advance were chosen for selection.Maximum potential gains increased with increasing mean genetic variance within bulks but showed only a slight response to increasing variation of the within bulk genetic variance. Negative correlations between bulk mean and genetic variance reduced maximum potential gains and positive correlations increased them but the effects were not large.A selection intensity of 5% among bulks seemed close to optimal for a wide range of parameters. Slightly more intense selection may be an advantage where the between bulk heritability is high, the within bulk variance is high, and the correlation between bulk mean and variance is high and positive. 相似文献
983.
984.
虚拟仪器技术在疲劳试验机功能改进中的应用研究 总被引:1,自引:0,他引:1
为了提高SVF-1E-01型电液伺服拉压疲劳试验机的测试精度、简化试验操作,应用虚拟仪器技术对其进行了改造。采用研祥工控集团的PCL-812pg多功能数据采集接口卡,在WIN98操作系统平台下,用面向对象的可视化编程环境Delphi5.0集成,设计了虚拟示波器及虚拟信号发生(合成)器。改进后的系统功能包括:模拟信号的采集与显示、单一及多路合成信号的产生及输出等。软件系统具有形象、直观、操作方便等特点。试验结果表明:控制信号精度较高,可以满足试验的要求。整个软、硬件系统接入拉压疲劳试验机中,完成该疲劳试验机 相似文献
985.
我国农业中的测土配方施肥 总被引:5,自引:0,他引:5
根据笔者的实践,阐述了目前我国正在进行的测土配方施肥行动的意义、测土配方施肥的主要工作内容、目前需要解决的科学问题等。同时介绍了目前在我国测土配方施肥中土壤养分化验的新方法等。 相似文献
986.
987.
Jan Ahlers 《Journal of Soils and Sediments》2001,1(3):168-174
In the risk assessment of industrial chemicals, an assessment of the risk to soil should be performed whenever relevant inputs
occur via the following pathways: application of sewage sludge, wet or dry deposition, application as a pesticide constituent
(e.g. solvent or metabolite), irrigation. An evaluation of the results for 34 chemicals from the first EU priority list showed
that only 35% of the risk assessments for the terrestrial compartment were performed on the basis of at least 2 valid tests
with soil organisms. In the vast majority of cases, the equilibrium partitioning method was used to extrapolate from aquatic
to soil toxicity. However, no indications exist for a correlation between aquatic and terrestrial toxicity. Moreover, the
exposure routes for soil organisms (uptake via pore water, air included in soil pores, ingestion of soil particles) are much
more complex than those for aquatic organisms. As a new approach, it is therefore suggested that, in cases of relevant exposure
(e.g. estimated or measured concentrations of >10 μg/kg), an assessment should generally be performed on the basis of valid
terrestrial tests rather than on an extrapolation from the aquatic toxicity. It is recommended that prolonged exposure tests
should be used already for an initial assessment of substances that have a strong tendency to adsorb on soil particles and
thus a long residence time in soil. A decision scheme for the risk assessment of industrial chemicals in soil is presented,
trigger values, testing strategies as well as assessment factors for derivation of a Predicted No Effect Concentration (PNECsoil) are discussed. An example of a terrestrial risk assessment for substances from the first EU priority list is given in order
to illustrate current practice. 相似文献
988.
规模化畜禽养殖污染气体现场检测方法与仪器研究进展 总被引:3,自引:3,他引:3
随着中国畜禽生产的规模化和集约化,畜禽舍内饲养密度增大,产生了许多污染气体。这些污染气体含有大量的氨、硫化物和挥发性有机物等有毒有害成分,不仅影响畜禽的正常生长,而且当这些污染气体扩散到大气中,会对大气环境造成环境污染,严重影响城乡的空气质量,使人类生存环境不断恶化,危害饲养人员及周围居民的身体健康。本文阐述了几种典型污染气体特征,综述了国内外规模化畜禽养殖主要污染气体现场检测方法和分析仪器研究现状,为实现对污染气体进行快速、准确检测,并判定其成分与浓度提供十分必要的依据,也为中国畜禽养殖污染气体检测技术的发展提供一定参考。 相似文献
989.
本文介绍了一个土壤养分状况系统研究方法,该方法包括土壤样品11种元素的速效含量测定、土壤对7种营养元素的吸附试验、盆栽试验和田间试验。应用该方法研究了104个土壤养分状况,盆栽试验发现100个土壤缺氮,101个缺磷,60个缺钾,38个缺锌,23个缺硫,22个缺硼,分别有19、18、14、13、11和3个土壤缺钼、钙、镁、铜、锰和铁。盆栽试验得到的结果在部分土壤的田间试验中得到了验证。 相似文献
990.