全文获取类型
收费全文 | 16935篇 |
免费 | 786篇 |
国内免费 | 3414篇 |
专业分类
林业 | 361篇 |
农学 | 3288篇 |
基础科学 | 926篇 |
3170篇 | |
综合类 | 8669篇 |
农作物 | 1820篇 |
水产渔业 | 236篇 |
畜牧兽医 | 596篇 |
园艺 | 209篇 |
植物保护 | 1860篇 |
出版年
2024年 | 144篇 |
2023年 | 341篇 |
2022年 | 547篇 |
2021年 | 586篇 |
2020年 | 670篇 |
2019年 | 668篇 |
2018年 | 568篇 |
2017年 | 749篇 |
2016年 | 852篇 |
2015年 | 735篇 |
2014年 | 817篇 |
2013年 | 1100篇 |
2012年 | 1262篇 |
2011年 | 1109篇 |
2010年 | 1028篇 |
2009年 | 1000篇 |
2008年 | 879篇 |
2007年 | 1028篇 |
2006年 | 870篇 |
2005年 | 827篇 |
2004年 | 608篇 |
2003年 | 584篇 |
2002年 | 459篇 |
2001年 | 465篇 |
2000年 | 403篇 |
1999年 | 338篇 |
1998年 | 313篇 |
1997年 | 268篇 |
1996年 | 294篇 |
1995年 | 229篇 |
1994年 | 201篇 |
1993年 | 200篇 |
1992年 | 213篇 |
1991年 | 156篇 |
1990年 | 154篇 |
1989年 | 121篇 |
1988年 | 91篇 |
1987年 | 67篇 |
1986年 | 47篇 |
1985年 | 16篇 |
1984年 | 26篇 |
1982年 | 14篇 |
1981年 | 15篇 |
1980年 | 9篇 |
1979年 | 9篇 |
1978年 | 12篇 |
1977年 | 12篇 |
1976年 | 15篇 |
1962年 | 9篇 |
1955年 | 4篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
21.
M. Özgen 《Journal of Agronomy and Crop Science》1991,166(5):318-325
The purpose of this study was to compare responsiveness to environment as well as the stability of newly developed promising lines with traditional commercial cultivars. Subject research was conducted in Ankara between 1983-1989 on common and durum wheat cultivars and lines. Regression coefficient (b) was used as the criterion of genotypes' responsiveness to environment whereas deviation from regression (S2 d) and coefficient of determination (r2 ) were used as stability parameters. Each experiment year was regarded as an environment and yield average of each year was used as the environmental index.
In consequence of the research, it was determined that new varieties with high yield, adaptable to diverse environments could be developed by means of hybridizations between parents having different genetic characteristics which were provided from diverse ecological regions. 相似文献
In consequence of the research, it was determined that new varieties with high yield, adaptable to diverse environments could be developed by means of hybridizations between parents having different genetic characteristics which were provided from diverse ecological regions. 相似文献
22.
23.
室内药效试验表明:麦根宁1号、敌力脱对小麦根腐病菌的生长均有良好的抑制作用。麦根宁Ⅰ号稀释300倍时,平均抑菌圈直径最大;敌力脱稀释800倍时,平均抑菌圈直径最大。同时,麦根宁Ⅰ号、敌力脱Ⅱ号,粉锈宁对小麦全蚀病菌生长也有明显的抑制作用。粉锈宁,麦根宁Ⅰ,Ⅱ号在稀释10000倍时,抑菌率均达100%;敌力脱在稀释15000倍时,平均抑菌率仍达89.7%。 相似文献
24.
25.
通过新型的小麦深施肥播种机的应用,实现了小麦深施肥播种,使种、肥分箱不同床,解决了过去化肥对种芽、幼苗的危害问题。达到了节本增效、增产增收的目的。 相似文献
26.
27.
Variation was investigated in 110 doubled haploid (DH) lines of wheat derived from wheat × maize crosses. Field observation revealed visible variations in 15 DH2 lines such as extreme dwarfism, low seed fertility, alteration of spike type and stripes. Six agronomic traits, i.e., heading date, spike number/ plant, culm length, spike length, seed fertility and grain weight were statistically analyzed in the DH2 and DH3 generations. Out of the 88 DH2 lines/DH3 groups, 26 %/64 % showed significant differences from the parental variety in the means of one or more traits. Ranges of the DH3 lines were larger than those of the DH2 lines, except for spike number/plant. Furthermore, analyses of variance within and between DH lines showed the presence of heterogeneity/heterozygosity in the DH2 lines/plants. These results indicated the occurrence of gametoclonal variation in the DH lines. It is considered that most of the variations detected were due to the colchicine treatment rather than to the 2,4-D treatment or in vitro culture. 相似文献
28.
29.
高校图书馆电子阅览室管理和服务 总被引:5,自引:1,他引:4
王新敏 《农业图书情报学刊》2004,16(12):81-83
本文介绍湖南科技大学图书馆电子阅览室管理现状与管理系统,探讨高校图书馆电子阅览室的软、硬件的管理维护,推行读者柔性管理和开展电子阅览室特色服务的途径。 相似文献
30.
Two-year field trials with winter wheat cultivars Batis and Toronto were conducted in Southern Bavaria, Germany, to investigate the possible causes of cultivar differences in response to N supply varying in total amount and time of application. Cultivar-related differences in grain yields were observed in treatments with low and medium N supply. High doses of N supply resulted in grain yield adjustment or grain yield advantage for cv. Toronto. The results of this study revealed a consistent, genotypic pattern in response to N fertilization in spite of strong seasonal effects. Systematic modifications in canopy growth rates in response to N supply were of particular relevance and a main factor for differences in tillering intensity resulting in modified stand densities. In the present study, cultivar differences in spike development and interactions with N supply related more to abortion than to initiation processes for number of spikelets and number of flowers per spikelet. High grain density (grains per m2) of cv. Toronto was evident during reproduction stages even under conditions of medium N supply. However, decreased growth rates during the later part of grain filling in combination with low 1000 grain weight, which was barely modified by N fertilization, allowed only partial utilization of this potential. It is assumed that sink limitations were of particular relevance for grain yield development in cv. Toronto, while cv. Batis combined a less intense response to N supply with more stability in the development of grain yield components. 相似文献