全文获取类型
收费全文 | 20439篇 |
免费 | 1125篇 |
国内免费 | 1205篇 |
专业分类
林业 | 2732篇 |
农学 | 1846篇 |
基础科学 | 536篇 |
2933篇 | |
综合类 | 8355篇 |
农作物 | 1410篇 |
水产渔业 | 610篇 |
畜牧兽医 | 1489篇 |
园艺 | 836篇 |
植物保护 | 2022篇 |
出版年
2024年 | 98篇 |
2023年 | 316篇 |
2022年 | 552篇 |
2021年 | 624篇 |
2020年 | 706篇 |
2019年 | 779篇 |
2018年 | 572篇 |
2017年 | 835篇 |
2016年 | 1004篇 |
2015年 | 768篇 |
2014年 | 957篇 |
2013年 | 1373篇 |
2012年 | 1699篇 |
2011年 | 1438篇 |
2010年 | 1171篇 |
2009年 | 1253篇 |
2008年 | 1137篇 |
2007年 | 1234篇 |
2006年 | 1015篇 |
2005年 | 814篇 |
2004年 | 698篇 |
2003年 | 540篇 |
2002年 | 431篇 |
2001年 | 387篇 |
2000年 | 325篇 |
1999年 | 289篇 |
1998年 | 232篇 |
1997年 | 193篇 |
1996年 | 166篇 |
1995年 | 194篇 |
1994年 | 140篇 |
1993年 | 142篇 |
1992年 | 133篇 |
1991年 | 128篇 |
1990年 | 113篇 |
1989年 | 90篇 |
1988年 | 68篇 |
1987年 | 61篇 |
1986年 | 25篇 |
1985年 | 10篇 |
1984年 | 6篇 |
1983年 | 4篇 |
1982年 | 7篇 |
1981年 | 7篇 |
1980年 | 8篇 |
1979年 | 5篇 |
1978年 | 6篇 |
1977年 | 4篇 |
1973年 | 3篇 |
1955年 | 4篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
951.
氟磺胺草醚的生物测定方法研究 总被引:3,自引:0,他引:3
试验利用对氟磺胺草醚敏感的玉米、向日葵、高粱为指示作物,利用土培法研究了不同条件下,氟磺胺草醚不同浓度对作物的抑制作用,并建立了氟磺胺草醚玉米生物测定方法——玉米株高法.试验结果表明,最佳生物测定条件为在27℃条件下,培养120 h.研究结果对土壤中氟磺胺草醚的快速测定和轮作换茬具有重要意义. 相似文献
952.
Mining Applicable Elite Alleles of Growth Duration,Plant Height and Panicle Number per Plant by Conditional QTL Mapping in Japonica Rice 总被引:1,自引:0,他引:1
JIANG Jian-hua ZHAO Qi-bing LIU Qiang-ming CHEN Lan CHEN Fu-long QIAO Bao-jian HONG De-lin 《水稻科学》2011,18(3):196-203
Unconditional and conditional QTL mapping were conducted for growth duration (GD), plant height (PH) and effective panicle number per plant (PN) using a recombinant inbred line (RIL) population derived from a cross between two japonica rice varieties Xiushui 79 and C Bao. The RIL population consisted of 254 lines was planted in two environments, Nanjing and Sihong, Jiangsu Province, China. Results showed that additive effects were major in all of QTLs for GD, PH and PN detected by the two methods, and the e... 相似文献
953.
在课时减少的情况下,为了保证和提高教学质量,探讨了园艺专业园艺植物害虫防治课程的教学内容、教学方法、教学手段、实践教学等方面的改革。结果表明,学生识别昆虫的能力、分析问题和解决生产实际等能力大大提高,得到了学生的一致好评。 相似文献
954.
955.
《Communications in Soil Science and Plant Analysis》2012,43(3):257-266
Abstract Procedures for S determination involving digestion of plant material with HNO3/HClO4 mixtures gave lower values than those using oxygen flask combustion. Tests on a range of S compounds showed that the HNO3/HClO4 procedure underestimated S present in methionine, cysteine and glutathione but S in sulfate and the glucosinolate, sinigrin, was not underestimated. Low recoveries using HNO3/HClO4 digestion procedures can be due both to incomplete oxidation of certain compounds and to gaseous losses during the vigorous boiling stage of digestion. 相似文献
956.
用8%胺鲜酯水剂在大白菜上进行田间药效试验,试验表明,在大白菜的大田返青期、生长期喷施,能有效地促进大白菜的生长,提高大白菜的产量。对大白菜中的维生素C和可溶性固形物含量等品质指标未发现有不良影响,且对品质有所提升。 相似文献
957.
植物病毒是一个极小的微粒.近几十年来,有关植物病毒的研究已取得很大的进展,对某些作物病毒的症状、寄生范围、传播途径、病理现象、鉴定方法及无毒苗培育途径等均已进行了深入的研究. 相似文献
958.
959.
A. K. Thakur S. Rath S. Roychowdhury N. Uphoff 《Journal of Agronomy and Crop Science》2010,196(2):146-159
The System of Rice Intensification (SRI) reportedly enhances the yields of rice (Oryza sativa L.) through synergy among several agronomic management practices. This study was conducted to investigate the effects on rice plant characteristics and yield by comparing the plants grown with different methods of cultivation – SRI vs. recommended management practices (RMP) focusing on the impact of different plant spacings. Performance of individual hills was significantly improved with wider spacing compared with closer‐spaced hills in terms of root growth and xylem exudation rates, leaf number and leaf sizes, canopy angle, tiller and panicle number, panicle length and grain number per panicle, grain filling and 1000‐grain weight and straw weight, irrespective of whether SRI or RMP was employed. Both sets of practices gave their highest grain yield with the spacing of 20 × 20 cm; however, SRI yielded 40 % more than the recommended practice. At this spacing, canopies also had the highest leaf area index (LAI) and light interception during flowering stage. The lowest yield was recorded at 30 × 30 cm spacing under both the practices, as a result of less plant population (11 m?2), despite improved hill performance. During the ripening stage, hills with wider spacing had larger root dry weight, produced greater xylem exudates, and transported these towards shoot at faster rates. These features contributed to the maintenance of higher chlorophyll levels, enhanced fluorescence and photosynthesis rates of leaves and supported more favourable yield attributes and grain yield in individual hills than in closely‐spaced plants. Moreover, these parameters further improved in SRI, apart from the enhanced percentage of effective tillers and showed substantial and positive impacts on grain yield (17 %) compared with recommended practice. In conclusion, wide spacing beyond optimum plant density, however, does not give higher grain yield on an area basis and for achieving this, a combination of improved hills with optimum plant population must be worked out for SRI. 相似文献
960.