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   2587篇
  免费   103篇
  国内免费   108篇
林业   13篇
农学   303篇
基础科学   69篇
  170篇
综合类   1016篇
农作物   190篇
水产渔业   1篇
畜牧兽医   24篇
园艺   812篇
植物保护   200篇
  2024年   22篇
  2023年   74篇
  2022年   81篇
  2021年   81篇
  2020年   90篇
  2019年   98篇
  2018年   66篇
  2017年   96篇
  2016年   110篇
  2015年   109篇
  2014年   142篇
  2013年   154篇
  2012年   229篇
  2011年   220篇
  2010年   184篇
  2009年   166篇
  2008年   112篇
  2007年   114篇
  2006年   107篇
  2005年   91篇
  2004年   62篇
  2003年   58篇
  2002年   34篇
  2001年   28篇
  2000年   33篇
  1999年   26篇
  1998年   23篇
  1997年   22篇
  1996年   17篇
  1995年   14篇
  1994年   12篇
  1993年   20篇
  1992年   18篇
  1991年   22篇
  1990年   15篇
  1989年   14篇
  1988年   7篇
  1987年   4篇
  1985年   4篇
  1984年   4篇
  1982年   3篇
  1981年   3篇
  1980年   2篇
  1978年   2篇
  1977年   3篇
  1962年   1篇
  1955年   1篇
排序方式: 共有2798条查询结果,搜索用时 125 毫秒
101.
102.
本文以“土佐狮子尖椒”品种为试材,对环状剥皮的作用进行探讨.经环状剥皮处理后,早期产量比对照增加29.4~52.6%;果实的干物质占有率也比对照有所增加,而根系的发育情况和直径大于1毫米的粗根数目均低于对照.叶面积指数、净光合率及相对生长率在进行环状剥皮后也低于对照.  相似文献   
103.
大豆重组自交系群体荚粒性状的QTL分析   总被引:16,自引:1,他引:16  
利用大豆重组自交系soy01群体中的255个家系进行2年田间试验,采用两种作图方法,寻找一粒荚、四粒荚、每荚粒数等5个荚粒性状稳定的QTL。结果表明,利用区间作图法,2年共找到24个荚粒性状QTL,解释的遗传变异为5%~80%;利用复合区间作图法,2年共找到27个荚粒性状QTL,解释的遗传变异为4%~73%。利用复合区间作图法,2年找到2个重复出现、稳定的四粒荚QTL和2个每荚粒数QTL,为大豆荚粒性状QTL的精细定位和分子标记辅助育种提供了基础和依据。  相似文献   
104.
Erskine  W. 《Euphytica》1985,34(1):105-112
Summary The genetic variation for seed yield losses and the response to selection for reduction of such losses was studied by a six-week delay in the timing of harvest in various segregating populations from four lentil crosses. The bulk segregating populations had previously been subjected to different numbers of selection by means of a delayed harvest. The loss in seed yield from a delayed harvest in the two seasons 1981/82 and 1982/83 accounted for 551 and 105 kg/ha seed, representing 34 and 11% of the yield from a correctly timed harvest respectively. Pod drop accounted for 65% of this loss, whereas dehiscence gave 35% of the loss in both seasons. The parents of cross 4 differed significantly for pod dehiscence, with genotype 74TA 550 showing relative indehiscence. Selection by means of a delayed harvest of bulk populations decreased pod dehiscence, mean seed weight and bulk mean yield.  相似文献   
105.
Summary Fourteen cultivars, one F1-hybrid and one half-wild type (Cind) of sweet pepper were tested on resistance to glasshouse whitefly. Several mutually significant levels of resistance were found. Most resistant appeared to be California Wonder, Severka M, Korál and Yolo Wonder. During the test sweet pepper plants were infested both with whiteflies and their parasite — Encarsia formosa, which caused the blackening of whitefly puparia. The blackened puparia are easily seen, enabling an easier and more rapid evaluation of the number of puparia present.  相似文献   
106.
生态有机肥不同混配基质对辣椒生长发育的影响   总被引:3,自引:0,他引:3       下载免费PDF全文
研究了“绿源”牌有机肥(生态有机肥)不同混配基质对辣椒生长发育的影响。结果表明:生态有机肥、蛭石、草炭按1∶1∶1或生态有机肥、蛭石按1∶1组配明显促进辣椒的生长发育,主要表现为株高、茎粗增大,叶片数增多,光合作用增强,开花座果期提早,生物产量及经济产量提高。生态有机肥与河砂、炉渣组配有利于提高辣椒果实的Vc含量。全部以生态有机肥作为基质栽培辣椒效果较差。  相似文献   
107.
Summary A total of 125 novel accessions of Capsicum annuum L. and Capsicum baccatum L. were screened for sources of resistance to Verticillium wilt (Verticillium dahliae Kleb). A soil infestation method with 2000 microsclerotia of V. dahliae per gram of planting medium, and a soil temperature of 25±3°C, identified 27 Capsicum accessions with resistance to Verticillium wilt. P.I. 215699 (a mixture of Capsicum baccatum var. microcarpum and Capsicum annuum), P.I. 535616 (Capsicum annuum), and P.I. 555614 (Capsicum annuum), had the lowest disease severity and the highest percentage of resistant plants.  相似文献   
108.
过氧化物酶及种子蛋白分析鉴定甜椒杂交种纯度   总被引:4,自引:2,他引:4  
用聚丙烯酰胺均匀胶和等电聚焦电泳技术,分析了甜椒种子及种苗的过氧化物同功酶谱和种子水溶蛋白图谱。在过氧化物酶谱带的两个位点PRX-1和PRX-2上,自交系亲本与F1杂交种有明显的差异。水溶蛋白的一个位点PROT亲本与F1有明显差异。供试甜椒组合的过氧化物酶和蛋白的图谱,分别具有这些位点。  相似文献   
109.
Summary A preliminary evaluation for resistance to chili thrips, Scirtothrips dorsalis Hood of 41 and 194 pepper (Capsicum annuum L.) germplasms during 1987 and 1988, respectively, indicated chili accessions may be a promising source of resistance. In contrast, all sweet pepper accessions tested were highly susceptible. A number of chili accessions produced a moderate yield, in spite of a high thrips infestation indicating tolerance to S. dorsalis. Rating for thrips damage was more reliable and efficient than estimating thrips numbers in screening pepper accessions for resistance to thrips. Highly significant, positive correlation between ratings at the seedling stage and final rating for thrips damage indicated the feasibility of screening pepper accessions at the seedling stage. Comparing the similarities in rating among accessions resulted in 40 distinct groups. The variance-covariance matrix of the data from these 40 groups was subjected to principal component analysis. This accounted for 56 and 18 per cent of the variation across the two principal axes, respectively. Projection of chili and sweet pepper accessions along these two axes revealed three distinct clusters. About 80 per cent of chili accessions formed the first cluster, 58 per cent of the sweet pepper accessions formed the second cluster and a third cluster exhibited intermediate ratings for thrips damage. The significance of these findings in relation to geographical divergence and resistance to thrips among pepper accessions is discussed.  相似文献   
110.
The colour of plant organs is a useful trait in crop breeding. The pod colours of soybeans primarily include black, brown and tan types, which are controlled by two classical genetic loci, L1 and L2. Most wild soybeans have black pods, which reflect a possible role in adaptation to the natural environment. Here, an improved chromosome segment substitution line (CSSL) population SojaCSSLP3 was established to identify the L1 gene. The segment on the 19th chromosome represented by the SSR marker Satt313 was found to link with locus L1. The region was further delimited three times with increased SSR and InDel markers using a population derived from a heterozygous plant of CSSL124 from SojaCSSLP3. The L1 gene was finally located in a 184.43‐kb region between SSR_19p09 and Indel_19P7. Thirteen putative genes in this region were analysed with qRT‐PCR. The expression level of Glyma19 g27460, which is a member of the SANT superfamily with a MYB DNA‐binding domain, was significantly upregulated in black pods and was recognized to be the most likely candidate for the L1 gene.  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