全文获取类型
收费全文 | 2418篇 |
免费 | 86篇 |
国内免费 | 88篇 |
专业分类
林业 | 31篇 |
农学 | 537篇 |
基础科学 | 44篇 |
263篇 | |
综合类 | 956篇 |
农作物 | 172篇 |
水产渔业 | 35篇 |
畜牧兽医 | 72篇 |
园艺 | 157篇 |
植物保护 | 325篇 |
出版年
2024年 | 12篇 |
2023年 | 29篇 |
2022年 | 62篇 |
2021年 | 62篇 |
2020年 | 81篇 |
2019年 | 76篇 |
2018年 | 68篇 |
2017年 | 79篇 |
2016年 | 97篇 |
2015年 | 87篇 |
2014年 | 122篇 |
2013年 | 148篇 |
2012年 | 137篇 |
2011年 | 165篇 |
2010年 | 133篇 |
2009年 | 111篇 |
2008年 | 104篇 |
2007年 | 116篇 |
2006年 | 97篇 |
2005年 | 100篇 |
2004年 | 47篇 |
2003年 | 69篇 |
2002年 | 48篇 |
2001年 | 38篇 |
2000年 | 45篇 |
1999年 | 50篇 |
1998年 | 28篇 |
1997年 | 39篇 |
1996年 | 26篇 |
1995年 | 32篇 |
1994年 | 21篇 |
1993年 | 30篇 |
1992年 | 30篇 |
1991年 | 24篇 |
1990年 | 22篇 |
1989年 | 32篇 |
1988年 | 28篇 |
1987年 | 18篇 |
1986年 | 27篇 |
1985年 | 10篇 |
1984年 | 12篇 |
1982年 | 4篇 |
1981年 | 3篇 |
1980年 | 3篇 |
1979年 | 3篇 |
1978年 | 3篇 |
1977年 | 8篇 |
1976年 | 3篇 |
1963年 | 1篇 |
1955年 | 1篇 |
排序方式: 共有2592条查询结果,搜索用时 15 毫秒
61.
DTA-6对两种食用豆生理代谢及产量的影响 总被引:1,自引:0,他引:1
为探究2-N,N-二乙氨基乙基己酸酯(diethyl aminoethyl hexanoate,DTA-6)对食用豆叶片的生理代谢及产量的调控效应,选用芸豆(英国红)和小豆(龙垦2号)为试验材料,采用大田完全随机试验方法,于芸豆和小豆的初花期叶面喷施DTA-6,以喷施清水为对照(CK),测定各生育时期叶片光合参数、碳代谢产物、干物质、产量及产量构成因素。结果表明:DTA-6提高了2种食用豆各生育期的SPAD值、盛花期和鼓粒期的净光合速率(Pn)、蒸腾速率(Tr)、气孔导度(Gs)和胞间CO2浓度(Ci),显著增加了叶片蔗糖和可溶性糖的含量,促进了叶片淀粉的积累;与CK相比,DTA-6提高了2种食用豆的地上部单株干物质积累量,并且显著提高了芸豆和小豆鼓粒期荚分配率;DTA-6可有效调控2种食用豆的单株荚数、单株粒数和百粒重,从而提高产量,DTA-6处理的芸豆和小豆产量分别较CK增加13.30%和12.91%,增产显著。 相似文献
62.
不同种植密度对3个小豆品种植株形态及产量的影响 总被引:1,自引:0,他引:1
采用两因素随机区组设计,以直立型小豆品种冀红20、冀红21和唐红201602为材料,分析6个种植密度对不同小豆品种植株形态特征及产量性状的影响。结果表明,品种和种植密度对小豆形态特征和产量性状的影响较大;底荚高度和第一节间长随着密度的增加而增加,主茎节数、主茎分枝数、单株结荚数、单荚粒数和百粒重随着种植密度的增加而减小,产量随种植密度的增加呈先增加后减少趋势;相同品种不同种植密度间和相同种植密度不同品种间的产量差异极显著(F值分别为49.36、99.35),品种与种植密度互作对产量的影响差异显著(F=3.91)。种植密度与株高、底荚高度呈极显著正相关,与第一节间长呈正相关,与茎粗、主茎分枝数和主茎节数呈极显著负相关。增加种植密度可增加小豆株高、底荚高度和第一节间长,有效减少主茎分枝数,有利于机械化收获。 相似文献
63.
蚕豆是青海重要的商品作物之一,随着青海蚕豆蛋白产业发展,对高蛋白蚕豆的需求增长比较快,研究不同基因型蚕豆在不同生态区的蚕豆蛋白质含量的差异,有利于按不同基因型蚕豆优势区域进行合理布局,保障青海蚕豆的有效供给和需求。采用紫外分光光度法分析结果表明:同一生态区同一类型大粒组不同基因型蚕豆的蛋白质含量差异不显著,而小粒组不同基因型蚕豆之间FE3、FE5、FE2和尕大豆与FE6、马牙的蛋白质含量差异极显著,但小粒蚕豆较大粒蚕豆的蛋白质含量高18.49%,不同生态区蚕豆蛋白质含量在品种间、环境间和品种与环境的交互效应差异极显著,蚕豆蛋白质含量随着海拔升高而降低,呈近似线性下降趋势。 相似文献
64.
中国蚕豆种质资源ISSR标记遗传多样性分析 总被引:7,自引:0,他引:7
利用ISSR标记对中国18个省(区)的527份春播区和秋播区蚕豆资源的遗传多样性与亲缘关系进行分析。结果表明,11个ISSR引物共扩增出278条清晰的条带,其中多态性条带268条(占96%)。不同地理来源蚕豆资源群间的基因多样性指数在0.1267~0.2509之间,平均为0.1716;Shannon指数范围为0.1932~0.3767,平均为0.2608。两指数均以内蒙古资源群最高,云南和甘肃资源群次之,江西资源群体最低。非加权配对算术平均法(UPGMA)的聚类分析和二维主成分分析(PCA)结果表明,中国春播区和秋播区蚕豆资源明显不同,浙江和四川的资源形成独立的组群,明显不同于其他省份,其遗传背景独特,有待进一步研究。中国蚕豆种质资源遗传多样性差异和遗传关系与其生长习性、生态分布及地理来源密切相关。 相似文献
65.
66.
Summary The adaptability and productivity of cool-season food legumes (chickpea, faba bean, lentil, pea) are limited by major abiotic
stresses including drought, heat, frost, chilling, waterlogging, salinity and mineral toxicities. The severity of these stresses
is unpredictable in field experiments, so field trials are increasingly supplemented with controlled-environment testing and
physiological screening. For drought testing, irrigation is used in dry fields and rain-out shelters in damp ones. Carbon
isotope discrimination (Δ13C) is a well-established screen for drought tolerance in C3 cereal crops which is now being validated for use in grain legumes,
but it is relatively expensive per sample and more economical methods include stomatal conductance and canopy temperature.
Chickpea lines ICC4958 and FLIP87-59C and faba bean line ILB938 have demonstrated good drought tolerance parameters in different
experiments. For frost tolerance, an efficient controlled-environment procedure involves exposing hardened pot-grown plants
to sub-zero temperatures. Faba beans Cote d’Or and BPL4628 as well as lentil ILL5865 have demonstrated good freezing tolerance
in such tests. Chilling-tolerance tests are more commonly conducted in the field and lentil line ILL1878 as well as derivatives
of interspecific crosses between chickpea and its wild relatives have repeatedly shown good results. The timing of chilling
is particularly important as temperatures which are not lethal to the plant can greatly disrupt fertilization of flowers.
Salinity response can be determined using hydroponic methods with a sand or gravel substrate and rapid, efficient scoring
is based on leaf symptoms. Many lines of chickpea, faba bean and lentil have shown good salinity tolerance in a single article
but none has become a benchmark. Waterlogging tolerance can be evaluated using paired hydroponic systems, one oxygenated and
the other de-oxygenated. The development of lysigenous cavities or aerenchyma in roots, common in warm-season legumes, is
reported in pea and lentil but is not well established in chickpea or faba bean. Many stresses are associated with oxidative
damage leading to changes in chlorophyll fluorescence, membrane stability and peroxidase levels. An additional factor relevant
to the legumes is the response of the symbiotic nitrogen-fixing bacteria to the stress. 相似文献
67.
Summary Genetics of resistance to Ascochyta fabae Speg. in Vicia faba L. was studied with a final objective to develop resistant faba bean varieties to Ascochyta blight. The study was conducted separately on 3 single spore isolates (AF10-2 and AF13-2 from Tunisia and AF4-3 from France) and belonging to different groups of virulence (GV1 and GV2). Important general combining ability (GCA) effects were found especially with isolates AF10-2 and AF4-3. Specific combining ability (SCA), although significant for the 3 isolates, was important only with AF13 -2, but less important than GCA. Additive gene effects were predominant to non-additive effects. Lines 29H and A8817 transmitted to their progenies resistance to the 3 isolates, whereas 14–12 and 19TB conferred resistance to their progenies only with isolates AF13-2 and AF4-3, respectively. In the material studied, resistance was generally controlled by dominant genes but also could be attributed to recessive genes although less frequent. Analysis of segregation in the F2 of 2 crosses between the resistant lines (A8817 and 29H) and the susceptible line (14–12) with isolate AF4-3 revealed dominant monogenic control at the level of leaves in the 2 resistant lines and, in addition, a recessive gene controlling resistance of stems. Non-allelic interactions were occasionally manifested and their origin appeared to be due to line 19TB. A recurrent selection scheme was proposed with the objective to develop improved open-pollination populations and synthetic varieties responding to the objective of the national Tunisian research programme on faba bean. 相似文献
68.
Growth trials were conducted outdoors in the UK to determine the yield, yield components and plant architectural differences
between determinate and indeterminate Phaseolus vulgaris bean plants. F3 lines derived from crosses between ‘Prelude’, a determinate cultivar and ‘V8’, an indeterminate landrace,
were grown together with the parents and ‘Carioca’, an indeterminate landrace from Brazil. Data were recorded on flowering
date, number of nodes on main stem at flowering, plant height at maturity, number of pods/plant, number of seeds/pod, number
of seeds/plant, 100-seed weight, seed mass/plant, percentages of diseased and healthy seeds/plant. Determinate F3 lines had
significantly lower (P < 0.05) seed mass/plant, fewer pods/plant, fewer seeds/pod, fewer seeds/plant, lower harvest index, shorter stems, earlier
date of flowering, fewer nodes at flowering and fewer healthy seeds/plant than indeterminate F3 lines. However, determinate
genotypes had significantly larger (P < 0.05) pods to accommodate their larger seeds compared with indeterminate lines. A similar situation was found when the
yield and yield components of ‘V8’, ‘Prelude’ and ‘Carioca’ were evaluated; the highest seed mass/plant was given by ‘V8’
and the lowest by ‘Prelude’. Furthermore, some indeterminate genotypes with Type IV growth habit yielded significantly higher
(P < 0.05) than the high-yielding parent, ‘V8’, indicating a positive influence on seed yield by crossing different genotypes. 相似文献
69.
酶法提取豆渣水溶性膳食纤维的研究 总被引:1,自引:0,他引:1
为了提高豆渣水溶性膳食纤维的得率,通过正交试验确定了提取水溶性膳食纤维的最佳工艺。研究结果表明,当纤维素酶添加量为4%,加水量为25mL/g,反应时间为2h,反应温度为50℃,反应pH值为5时,水溶性膳食纤维得率为13.7%,达到最大。 相似文献
70.