全文获取类型
收费全文 | 644篇 |
免费 | 15篇 |
国内免费 | 40篇 |
专业分类
林业 | 69篇 |
农学 | 127篇 |
基础科学 | 7篇 |
48篇 | |
综合类 | 269篇 |
农作物 | 80篇 |
水产渔业 | 4篇 |
畜牧兽医 | 63篇 |
园艺 | 22篇 |
植物保护 | 10篇 |
出版年
2024年 | 1篇 |
2023年 | 4篇 |
2022年 | 8篇 |
2021年 | 13篇 |
2020年 | 16篇 |
2019年 | 11篇 |
2018年 | 3篇 |
2017年 | 18篇 |
2016年 | 20篇 |
2015年 | 17篇 |
2014年 | 29篇 |
2013年 | 25篇 |
2012年 | 25篇 |
2011年 | 47篇 |
2010年 | 39篇 |
2009年 | 45篇 |
2008年 | 53篇 |
2007年 | 48篇 |
2006年 | 56篇 |
2005年 | 28篇 |
2004年 | 23篇 |
2003年 | 28篇 |
2002年 | 20篇 |
2001年 | 9篇 |
2000年 | 10篇 |
1999年 | 13篇 |
1998年 | 11篇 |
1997年 | 10篇 |
1996年 | 6篇 |
1995年 | 12篇 |
1994年 | 15篇 |
1993年 | 6篇 |
1992年 | 5篇 |
1991年 | 8篇 |
1990年 | 8篇 |
1989年 | 3篇 |
1987年 | 3篇 |
1986年 | 2篇 |
1963年 | 1篇 |
排序方式: 共有699条查询结果,搜索用时 15 毫秒
51.
Prediction of Fiber Composition and Silicification for Rice Straw with Near Infrared Reflectance Spectroscopy (NIRS) Technique 总被引:1,自引:0,他引:1
SHEN Heng-sheng CHEN Jun-chen ZHAO Wu-shan Ni De-bin TANG Bao-sha Valdes E V 《中国农业科学(英文版)》2002,1(10):1111-1115
The silicification of rice straw is a factor that affects the grain production and straw nutritive quality. The procedure of chemical analysis for silicon in straw is, however, time and labor consuming, and slightly poor in accuracy. The study has attempted to apply near infrared reflectance spectroscopy (NIRS)technique as an advanced alternative to predict the fiber composition and silicification in rice straw. Ninetytwo samples from different seasons and varieties were collected over the Fujian Province. Their chemical analyses were carried on the aspects of hemicellulose, cellulose, lignin, extractable and non-extractable silicon,and the results were used as a database for NIRS analyses. The prediction model was developed through modified partial least square regression (MPLS) for a calibration program. The factors that may affect the calibration, cross-validation and the prediction for the application of NIRS on rice straw were also discussed. 相似文献
52.
豌豆新品系8710-2选育报告 总被引:1,自引:1,他引:1
豌豆新品系8710-2是定西市旱作农业科研推广中心以77-441作母本,青-1作父本,通过有性杂交选育而成.该品系株高47.38 cm,千粒重220.90 g,生育期91 d,籽粒含粗蛋白284.2 g/kg、赖氨酸20.3 g/kg、粗脂肪13.4 g/kg,抗旱性强,耐根腐病,平均折合产量1 080.00 kg/hm2,比对照品种绿豌豆增产45.45%,丰产、稳产性好.适宜在定西市半干旱山区及其同类地区推广种植. 相似文献
53.
[目的]缓解镉对植物的危害。[方法]以豌豆种子为试材,CdCl2溶液浸种后,用不同浓度的CdCl2和ZnSO4溶液培养,蒸馏水为对照组(CK),研究了锌对镉胁迫下豌豆幼苗生长发育的影响。[结果]60 mg/L镉溶液处理发芽势比对照降低了3.28个百分点。锌能缓解镉对豌豆种子萌发早期的毒害效应。镉浓度为10 mg/L时,根长为对照的161.6%。镉浓度为151.66 mg/L时,根长最短,是对照的95.36%。镉浓度为10 mg/L时,分裂期细胞数比例最大,总畸变率最低;镉浓度为60 mg/L时,分裂期细胞数比例最小,畸变率最大。在镉浓度≤20 mg/L,10 mg/L锌能提高幼苗叶绿素含量。镉浓度为10 mg/L和20 mg/L时,POD酶谱带比对照少1条;镉浓度为60 mg/L时,比对照多1条。[结论]锌对镉胁迫下的豌豆有解毒效应,以10 mg/L时解毒效应最好。 相似文献
54.
棉株生理年龄对纤维加厚发育及纤维比强度形成的影响 总被引:13,自引:7,他引:13
【目的】研究棉株生理年龄对棉纤维加厚发育及纤维比强度形成的影响。【方法】通过设置播期试验使位于棉株不同部位的棉花"三桃"(伏桃、早秋桃和晚秋桃)的棉纤维加厚发育期(铃龄25~50 d)处于相同的温度条件下(统计伏桃、早秋桃和晚秋桃棉纤维加厚发育期日均温分别为22.0、19.4和15.3℃)。【结果】棉花"三桃"的棉纤维加厚发育及纤维比强度受温度和棉株生理年龄的双重影响,棉株生理年龄是影响伏桃、早秋桃棉纤维加厚发育的主要因子,对棉株上部果枝的伏桃和下部果枝的早秋桃棉纤维加厚发育具有显著影响,铃重、衣分和纤维比强度均明显低于其他部位;棉纤维加厚发育期低温则是影响晚秋桃棉纤维加厚发育及纤维比强度的首要因子。在本试验15.3℃的温度条件下,棉纤维蔗糖合成酶活性显著降低,β-1,3-葡聚糖酶活性显著升高,同时纤维素累积量和累积速率均显著降低,棉花铃重低于2 g,纤维比强度低于20 CN·tex-1。【结论】棉株生理年龄对伏桃、早秋桃和晚秋桃纤维比强度的影响作用依次增强。 相似文献
55.
56.
Seed dressing with fungicides adversely affects the structure and function of beneficial soil microbial communities and consequently crop yield. This study was aimed to evaluate the impact of technical-grade fungicide tebuconazole on plant growth promoting potentials of tebuconazole-tolerant Rhizobium isolate MRP1. The performance of the isolate MRP1-inoculated pea plants grown in tebuconazole treated soils was also assessed. Generally, the three concentrations [100 (recommended dose), 200 and 300 μg kg−1 soil] of tebuconazole when used alone, adversely affected the growth, symbiosis, grain yield and nutrient uptake by pea plants. Concentration dependent phytotoxicity of tebuconazole was observed for all the measured parameters. On the contrary, fungicide tolerant Rhizobium sp. MRP1 in the presence of fungicide increased the measured parameters at all tested concentrations. As an example, when inoculant MRP1 was also used with 300 μg tebuconazole kg−1 soil, it substantially increased the root nitrogen, shoot nitrogen, root P, shoot P, seed yield and grain protein by 20, 19, 50, 31, 15 and 7%, respectively, when compared with uninoculated plants grown in fungicide-treated soils. The study suggests that the plant growth promoting Rhizobium sp. MRP1 can be used as bacterial inoculant to increase the production of pea in soils polluted with fungicides. 相似文献
57.
D.?RubialesEmail author M.?T.?Moreno J.?C.?Sillero 《Genetic Resources and Crop Evolution》2005,52(7):853-861
Orobanche crenata Forsk. is a major constraint for pea production in Mediterranean and East Asian countries. To solve the problem of the lack of
resistance in pea cultivars, a screening for resistance was performed under field conditions in a germplasm collection of
575 accessions of Pisum sativum L. No complete resistance was found but varying levels of resistance were identified and confirmed in further field seasons
and in pots experiments in the greenhouse. Resistance was quantitative resulting in a reduction in the number of emerged broomrapes
per pea plant. Broomrape infection and expression of resistance proved to be highly influenced by environmental conditions.
Resistance is the consequence of the combination of several resistance mechanisms preventing or hampering establishment of
broomrape and/or development of established tubercles. Resistance identified could suffice to prevent broomrape damage in
normal years, but might need to be implemented with other control measures in very conducive years. Resistant accessions have
been crossed with pea cultivars and submitted to a breeding programme in which accumulation of levels of resistance to broomrape
is a priority. 相似文献
58.
张腊梅 《青海畜牧兽医杂志》2002,32(4):15-15
通过对终年放牧的青海藏羊毛纤维长度5cm区段含硫量的测定,结果表明青海藏羊毛纤维不同长度区段的含硫量不同,含硫量顶峰值前,随着长度增加含硫量逐步增加,但成年公羊顶峰值后随机度增加,含硫量逐渐减少。青海藏羊毛长5cm各区段各硫量差异不显著(P>0.05),毛长与含硫量除成年公羊为强的负相关(r=-0.56964),其余各性能年龄组内均为弱的正相关关系,相关系数r=-0.116182-0.354898. 相似文献
59.
CUI Zhi-feng HAO Yan-zhou SUN Wei-ming LI Deng-lai Sea College of Yantai University Yantai China 《华北农学报》2006,(Z3)
纤维素是鱼类重要的营养素,文章分析了有关纤维素的作用、鱼类饲料中纤维素的适宜含量及影响因素、饲料中纤维素含量过多的危害,同时,对一些研究方法也做了相应评价,对未来的研究方向提出了个人观点。 相似文献
60.
选用9只瘘管羊,采用完全随机区组设计(以体质量为区组)研究日粮中分别添加30mg/kg和60mg/kg氢醌对干物质、中性洗涤纤维(NDF)和酸性洗涤纤维(ADF)在瘤胃中降解率和降解参数的影响。结果表明,在日粮中添加30mg/kg和60mg/kg氢醌可以明显提高干物质、NDF和ADF的有效降解率(P<0.05),但对外流速度(k)没有显著影响(P>0.05)。应用脲酶抑制剂可以显著提高NDF的48h降解率,ADF的24h和48h的降解率(P<0.05)。上述结果表明,在含有尿素的日粮中添加适宜水平的氢醌有利于氨的释放与底物发酵同步,从而导致了纤维物质消化率的提高。 相似文献