全文获取类型
收费全文 | 653篇 |
免费 | 30篇 |
国内免费 | 64篇 |
专业分类
林业 | 20篇 |
农学 | 28篇 |
基础科学 | 7篇 |
299篇 | |
综合类 | 246篇 |
农作物 | 19篇 |
水产渔业 | 12篇 |
畜牧兽医 | 75篇 |
园艺 | 9篇 |
植物保护 | 32篇 |
出版年
2024年 | 6篇 |
2023年 | 10篇 |
2022年 | 23篇 |
2021年 | 29篇 |
2020年 | 22篇 |
2019年 | 27篇 |
2018年 | 25篇 |
2017年 | 43篇 |
2016年 | 27篇 |
2015年 | 24篇 |
2014年 | 29篇 |
2013年 | 81篇 |
2012年 | 83篇 |
2011年 | 48篇 |
2010年 | 22篇 |
2009年 | 26篇 |
2008年 | 34篇 |
2007年 | 25篇 |
2006年 | 19篇 |
2005年 | 19篇 |
2004年 | 21篇 |
2003年 | 12篇 |
2002年 | 15篇 |
2001年 | 23篇 |
2000年 | 6篇 |
1999年 | 9篇 |
1998年 | 1篇 |
1997年 | 5篇 |
1996年 | 7篇 |
1995年 | 11篇 |
1994年 | 2篇 |
1993年 | 1篇 |
1992年 | 2篇 |
1990年 | 2篇 |
1989年 | 4篇 |
1988年 | 2篇 |
1984年 | 1篇 |
1983年 | 1篇 |
排序方式: 共有747条查询结果,搜索用时 15 毫秒
91.
升华硫配合杀螨剂防治蜂螨效果的比较研究 总被引:3,自引:1,他引:2
[目的]比较升华硫配合杀螨剂防治蜂螨效果。[方法]2007~2009年3次于同一个蜂场采用同一种方法对升华硫配合杀螨剂防治蜂螨效果进行了试验。[结果]升华硫配合杀螨剂对于消灭存在蜂脾上及寄生于封盖蛹的蜂螨有明显效果,对于消灭成年工蜂身体上的蜂螨效果不明显。施药后杀灭大蜂螨的效果以第1天最佳,此后逐日减少;杀灭小蜂螨的效果以第2天最佳,此后逐日减少,表明在2~5 d再施治1~2次,可达到理想的防治效果。在小蜂螨大量滋生时,采用升华硫配合杀螨剂有较为理想的防治效果。[结论]该防治技术可为大、小蜂螨严重危害地区的养蜂生产提供服务。 相似文献
92.
93.
Watson Matamwa Chris Guppy Isa Yunusa 《Communications in Soil Science and Plant Analysis》2018,49(4):433-443
As single superphosphate availability decreases due to closure of aging manufacturing plants increasing attention is being paid to alternative phosphorus (P) and sulfur (S) sources. This glasshouse study, conducted under non-leaching conditions was undertaken to evaluate the S supplying capacity of gypsum, S bentonite, elemental S (ES) and a range of P containing fertilizers and those where ES was added as a coating or incorporated. The magnitude of crop response in terms of shoot biomass to applied S fertilizer sources followed the order of sulfates > powdered ES > coated/incorporated ES > S/bentonite. These results indicate that fertilizers containing a mixture of sulfate and micronized ES (<75 µm), either incorporated within the granule or coated onto the fertilizer are agronomically effective. The results also suggest that local S coating of finished fertilizers is a feasible alternative to S incorporation undertaken at a central fertilizer plant. 相似文献
94.
In most soil ecosystems, soil biological activity and associated processes are concentrated in the rhizosphere soil and is influenced by the external application of plant nutrients. The impacts of boron and sulfur on soil biological properties were evaluated in an Aeric Haplaquept (pH 5.7) growing rapeseed (Brassica campestris L.) as a test crop. Application of boron (B) at 2 mg kg?1 in combination with sulfur (S) at 30 mg kg?1 (B2S30) resulted in highest available Boron and sulfur of 0.239 and 15.4 mg kg?1, respectively and registered 62.5% and 71.3% increase over control (B0S0) at 60 days of crop growth compared to individual applications. The microbial populations viz. phosphate solubilizing microorganisms (PSM) and nitrogen fixing bacteria (NFB) were the highest of 52.63 and 85.87 × 105 g?1 soil, respectively, CFU in B2S30 treatment at 60 days and adjudged as the best treatment combination for enhancement of soil biological indices and seed yield. 相似文献
95.
Mehdi Karimizarchi Amin Soltangheisi Aminuddin Husin Mohd Khanif Yusop Radziah Othman 《Journal of plant nutrition》2018,41(14):1798-1806
A glasshouse experiment was conducted to elucidate the influence of elemental sulfur (S) application rates (0, 0.5, 1.0, and 2.0 g S kg?1 soil) on the release and uptake of S at 0, 20, and 40 days after incubation. Results showed that there was a progressive upward trend in maize leaves, stem, and root S content with application of elemental S. However, maize production followed a nonlinear model. Plants grown in untreated soils suffer from S deficiency and addition of elemental S at a rate of 0.5 g S kg?1 soil alleviated S deficiency. The decrease in maize performance due to the highest S application rate was not related to S toxicity. The greatest leave, stem, and root productions were obtained at S concentrations of 0.41, 0.58, and 0.2%, respectively. Overall, application of elemental S at a rate of 0.5 g S kg?1 soil is recommended for maize performance improvement. 相似文献
96.
A. Basumatary J. J. Shangne K. N. Das D. Bhattacharyya 《Journal of plant nutrition》2018,41(11):1436-1443
A field experiment was conducted to assess the effect of sulfur (S) fertilization on distribution of S in soil and use efficiency on blackgram in subtropical Inceptisol of acidic soil of Assam, India. Five levels of S were applied (0, 10, 20, 30 and 40 kg S ha?1) along with recommended dose of nitrogen, phosphorus and potassium. Available S content gradually decreased with the advancement of crop growth stages and lowest value was observed at 60 DAS. Different S fractions were found to increase with increasing levels of S application and 40 kg S ha?1 resulted the highest content for all S fractions. The grain and stover yield of blackgram increased significantly up to 20 kg S ha?1 which was 95.69% higher over control. Agronomic efficiency, apparent S recovery and recovery efficiency of S were higher at 10 kg S ha?1and found decreased with increase in level of S. 相似文献
97.
98.
氮肥底追比例及施硫对小麦氮素吸收利用的调控 总被引:3,自引:0,他引:3
为明确氮肥底追比例与施硫间的互作效应,采用盆栽方式,以京冬8号和济麦20为供试材料,设置氮肥底追比例为3∶7(N_1)、5∶5(N_2)和7∶3(N_3)3个处理水平,每个底追比例下设置2个硫肥施用量:0kg·hm~(-2)(S0)和45kg·hm~(-2)(S_1),运用15N示踪技术研究开花期、成熟期营养器官及籽粒中氮素积累、分配以及对不同来源氮素利用的情况,同时对花后营养器官贮藏氮素的转运、对籽粒的贡献率及氮素利用效率进行分析比较。结果表明,2个小麦品种植株中积累氮素主要来自肥料氮,京冬8号成熟期来自肥料氮的积累量达60%~70%,而济麦20则达70%~80%。氮肥底追比例及硫肥互作对2个品种氮素吸收、转运和分配的影响存在差异,其中京冬8号成熟期籽粒氮素积累量、营养器官贮藏氮素花后的转运量、转运率、对籽粒的贡献率、籽粒产量以及氮肥的利用效率均在N_1S_0时较高;济麦20营养器官贮藏氮素花后的转运量、转运率、对籽粒的贡献率在N1S0时较高,而在N3S1时,成熟期籽粒氮素积累量、籽粒产量、氮肥的利用效率均较高。综上所述,本试验栽培环境下,氮肥底追比例为N1时能够提高花前贮藏氮素的转运量、转运率、对籽粒的贡献率、籽粒蛋白质含量及氮素收获指数;氮肥底追比例为N3时有利于提高籽粒产量、氮肥生产效率。综合考虑籽粒产量、氮肥生产效率、氮肥利用效率和氮素收获指数,京冬8号最优肥料组合为N_1S_0,济麦20最优肥料组合为N_3S_1。本研究结果为冬小麦大田生产中合理的肥料运筹提供了理论参考。 相似文献
99.
Walter D. Carciochi Guillermo A. Divito Lucrecia A. Fernández Hernán E. Echeverría 《Journal of plant nutrition》2017,40(9):1231-1242
Wheat plants were cultivated in pots with the objective of evaluating the effect of two sulfur (S) rates (+S and ?S) on (i) shoot growth, S and nitrogen (N) uptake and nitrogen use efficiency (NUE) and (ii) root growth and architecture and its relations with S and N uptake. Plant samplings were at Z39, Z51 and Z92 stages. Shoot mass and NUE were greater in +S treatment at the three stages. ?S treatment increased root growth at Z39 (14% more length and 16% more tips) in comparison with +S, but the opposite occurred at Z51 (31% less area and 42% less mass). S uptake per unit root mass, area and length were greater in +S treatment at Z39 and Z51. A similar pattern was determined for nitrogen uptake (Nu) at Z39, but the opposite occurred at Z51. This indicates that Nu is mainly controlled by shoot growth and not by root growth. 相似文献
100.
Francisco R Badenes‐Perez Michael Reichelt David G Heckel 《Pest management science》2010,66(8):832-838
BACKGROUND: The effect of sulfur fertilisation on chemical constituents of yellow rocket, Barbarea vulgaris (R. Br.), was studied with regard to its potential use as a trap crop for the diamondback moth, Plutella xylostella (L.) (Lepidoptera: Plutellidae). Two types of B. vulgaris var. arcuata were used: the G‐type, resistant to P. xylostella and proposed as a ‘dead‐end’ trap crop, and the P‐type, not resistant to P. xylostella and used as a control. RESULTS: In G‐type B. vulgaris, sulfur fertilisation increased the content of the dominant glucosinolate (S)‐2‐hydroxy‐2‐phenylethylglucosinolate by 20%. Sulfur fertilisation did not significantly change levels of the saponins 3‐0‐β‐cellobiosylhederagenin and 3‐0‐β‐cellobiosyloleanolic acid, known to act as feeding deterrents for P. xylostella larvae. In P‐type B. vulgaris, the same levels of sulfur fertilisation did not change the glucosinolate content significantly. Two‐choice oviposition preference tests with B. vulgaris plants showed that P. xylostella laid 144% and 45% more eggs on G‐ and P‐type plants with sulfur fertilisation respectively. CONCLUSIONS: The studies suggest that sulfur fertilisation could increase the effectiveness of G‐type B. vulgaris as a trap crop for P. xylostella. The effect of plant sulfur fertilisation on P. xylostella oviposition preference is associated with a quantitative glucosinolate increase, but other compounds could also be involved. Copyright © 2010 Society of Chemical Industry 相似文献