首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   22901篇
  免费   1465篇
  国内免费   3271篇
林业   1552篇
农学   3430篇
基础科学   1091篇
  3441篇
综合类   11970篇
农作物   2611篇
水产渔业   195篇
畜牧兽医   596篇
园艺   808篇
植物保护   1943篇
  2024年   123篇
  2023年   411篇
  2022年   639篇
  2021年   733篇
  2020年   800篇
  2019年   798篇
  2018年   627篇
  2017年   898篇
  2016年   1195篇
  2015年   965篇
  2014年   1462篇
  2013年   1402篇
  2012年   2022篇
  2011年   1732篇
  2010年   1387篇
  2009年   1396篇
  2008年   1198篇
  2007年   1294篇
  2006年   1127篇
  2005年   1055篇
  2004年   775篇
  2003年   719篇
  2002年   565篇
  2001年   561篇
  2000年   473篇
  1999年   417篇
  1998年   370篇
  1997年   317篇
  1996年   330篇
  1995年   265篇
  1994年   250篇
  1993年   237篇
  1992年   241篇
  1991年   178篇
  1990年   169篇
  1989年   125篇
  1988年   106篇
  1987年   78篇
  1986年   50篇
  1985年   19篇
  1984年   26篇
  1982年   13篇
  1981年   16篇
  1980年   8篇
  1979年   10篇
  1978年   12篇
  1977年   11篇
  1976年   15篇
  1962年   10篇
  1955年   4篇
排序方式: 共有10000条查询结果,搜索用时 203 毫秒
91.
西梅的果实是一种具有较高经济价值的储藏器官。新疆是西梅的主要产区之一,为使西梅的果实能具有较高的品质和产量,在适宜砧木的选择、优良品种的搭配、建园模式、高效栽培树形、土肥水管理和病虫害防治等方法和技术上都要有较高的要求。文章综述目前西梅的研究,结合新疆生产现状总结出提高西梅果实品质和产量的一系列方法和措施。  相似文献   
92.
93.
在粮食作物中,马铃薯属于关键,诸多国家都是马铃薯产国,我国马铃薯种植栽培面积也十 分广泛,所以,需要针对于马铃薯特征全面普及其种植与栽培技术,以此来保障马铃薯总产量。  相似文献   
94.
灵山县贯彻落实国家和自治区部署,加快推进优质高产、高糖糖料蔗基地建设,目前已建成近1333.4hm2“双高”基地,并通过实施“双高”糖料蔗高产种植栽培技术,平均亩产达到8T,蔗糖分达到14%以上。  相似文献   
95.
小麦生长发育受冻害影响,而不良的环境条件严重危害小麦成长。冻害主要是指因温差骤降且时间过长影响小麦成长的情况。漯河地区冬季小麦冻害情况极为严重,而二类、三类麦田屡见不鲜,冬季冻害会造成极为严重的经济损失,只有针对其实际情况进行深入分析,并采取有效举措予以应对,即能够保证漯河地区小麦的稳定产量。  相似文献   
96.
目前由于我国社会经济的发展,对小麦的需求越来越大,因此为小麦的种植带来了较大的商 机,但在小麦栽培中还具有多种问题,需要通过针对性的措施予以解决。随着农业种植结构的逐步调 整,怎样提升种植小麦栽培质量就显得十分重要。本文对小麦栽培种常见的问题与措施展开探究。  相似文献   
97.
Herbage production is regarded as having environment-friendly credentials. However, as the ruminant production it supports is facing major challenges on sustainability, environmental footprint and human health concerns, EU herbage cultivar testing must contribute to the solutions. Before new cultivars can be sold in a member state (MS) and gain EU-wide marketing, they must pass official tests to prove they are both novel (distinct, uniform and stable, DUS) with improved value for cultivation and use (VCU). Herbage species present specific challenges, as their allogamy imposes a wide within-cultivar variation that adds complexity to DUS tests and their “value” is only realized in ruminant produce. Current VCU systems measure production, chemical composition and disease/stress tolerances, often on large numbers of candidate cultivars, but prohibitive labour costs and logistics mean that animal intake, ruminant output or environmental benefits cannot be measured directly. Furthermore, some candidate cultivars with proven superior VCU fail DUS even though the non-distinct comparison is with a significantly lower performing registered cultivar. To resolve these problem cases, a “vmDUS” distinctness tool is proposed, which uses molecular markers but conforms to UPOV-declared principles. A short overview of current grassland research shows smart proxy measures of animal value can easily and quickly be adopted into an integrated pan-European (EU-VCU) test network. The proposed EU-VCU scheme will reallocate test resources to conduct these additional tests by placing MS in data sharing collaborations, while retaining their national listing authority. The benefits to all stakeholders from adopting these new testing procedures are considered.  相似文献   
98.
In this study, the effect of immature wheat flour (IWF) on the fermentation activity of lactic acid bacteria (LAB) and on the nutritional quality properties of bread were evaluated. IWF was added in the as the ratio of 10g/100g in sourdough fermentation medium, and the fermentation activity (total LAB, pH, titration acidity (TA), and total reducing sugar (TRS)) of LAB cultures was monitored. Additionally, some physical quality characteristics (specific volume, texture profile and colour value), estimated glycaemic index (eGI), rapidly digestible starch (RDS), slowly digestible starch (SDS), and the total dietary fibre content of sourdough bread were determined. According to the statistical test, it was revealed that the IWF addition stimulated LAB growth and increased their fermentation activity. The pH of the fermentation medium decreased from 6.57 to 3.50, and TA raised from 0.13% to 1.2% in 48 h. The highest TRS content was determined in IWF enriched sourdough samples, and as a result of this, the eGI of sourdough bread increased. Compared to the control sample, the SDS and total dietary fibre content were higher in IWF added sourdough bread, and a positive correlation was noted between these two components. IWF utilisation of sourdough bread formulation increased the hardness value by nearly 50%.  相似文献   
99.
Unpredictable temperatures and rainfall associated with climate change are expected to affect wheat (Triticum aestivum L.) production in various countries. The development of climate-resilient spring wheat cultivars able to maintain grain yield and quality is essential to food security and economic returns. We tested 54 CIMMYT spring bread wheat genotypes, developed and/or released over a span of 50 years, in the field for two years under optimum sowing dates, as well as using two delayed sowing dates to expose crops to medium and severe heat-stress conditions. The grain yield and yield components were severely affected as the heat-stress increased. Two contrasting groups of 10 lines each were identified to determine the effect of heat-stress on bread-making quality. The first set included entries that produced high yields in optimal conditions and maintained higher yields under heat-stress (superior-yielding lines), while the second set included genotypes that did not perform well in the environment with high temperature (inferior-yielding lines). We identified genotypes exhibiting bread-making quality stability, as well as the quality traits that had higher correlation with the loaf volume in the environment without stress and under heat-stress. Of all the quality traits tested, dough extensibility (AlvL) and grain protein content had a significant influence in heat-stress adaptation. Most of the lines from the superior-yielding group were also able to maintain and even improve quality characteristics under heat-stress and therefore, could be used as parents in breeding to develop high-yielding and stable quality wheat varieties.  相似文献   
100.
Whole wheat products have gained popularity in recent years due to the health and nutritional benefits, with Asian salted noodles as one formulation. However, there is a general perception of decreased product quality and sensory acceptance of whole wheat noodles This study examined changes to sensory properties, texture (tensile and compressive strength), color, and cooking loss of noodles prepared from blends of wheat flour and bran that underwent five forms of hydro, thermal, pressure and their combined treatments: autoclaving, extrusion, jet-cooking, puffing, and roasting. Including the control (bran without processing) all six treatments were deemed palatable by sensory panel evaluation despite having statistically significant differences in physiochemical and sensory properties. For instance, 10 of the 22 sensory properties demonstrated significant differences among treatments. Bran processing tended to result in weaker (tensile and compressive strength) and stickier noodles while allowing for greater uptake of water during cooking.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号