全文获取类型
收费全文 | 704篇 |
免费 | 81篇 |
国内免费 | 1篇 |
专业分类
林业 | 22篇 |
农学 | 12篇 |
基础科学 | 3篇 |
70篇 | |
综合类 | 119篇 |
农作物 | 18篇 |
水产渔业 | 49篇 |
畜牧兽医 | 425篇 |
园艺 | 14篇 |
植物保护 | 54篇 |
出版年
2023年 | 16篇 |
2022年 | 13篇 |
2021年 | 34篇 |
2020年 | 52篇 |
2019年 | 38篇 |
2018年 | 23篇 |
2017年 | 32篇 |
2016年 | 25篇 |
2015年 | 13篇 |
2014年 | 20篇 |
2013年 | 21篇 |
2012年 | 29篇 |
2011年 | 54篇 |
2010年 | 18篇 |
2009年 | 19篇 |
2008年 | 30篇 |
2007年 | 35篇 |
2006年 | 25篇 |
2005年 | 41篇 |
2004年 | 34篇 |
2003年 | 11篇 |
2002年 | 8篇 |
2001年 | 9篇 |
2000年 | 13篇 |
1999年 | 6篇 |
1998年 | 4篇 |
1996年 | 4篇 |
1993年 | 4篇 |
1989年 | 6篇 |
1988年 | 7篇 |
1987年 | 8篇 |
1986年 | 4篇 |
1985年 | 3篇 |
1984年 | 10篇 |
1983年 | 7篇 |
1982年 | 4篇 |
1979年 | 6篇 |
1978年 | 5篇 |
1977年 | 8篇 |
1976年 | 6篇 |
1975年 | 5篇 |
1974年 | 4篇 |
1973年 | 8篇 |
1972年 | 5篇 |
1971年 | 7篇 |
1969年 | 3篇 |
1968年 | 5篇 |
1967年 | 3篇 |
1966年 | 6篇 |
1943年 | 3篇 |
排序方式: 共有786条查询结果,搜索用时 31 毫秒
781.
782.
Jessica S. Wong Adam C. Cave Danielle M. Lightle Walter F. Mahaffee Steve E. Naranjo Nik G. Wiman J. Megan Woltz Jana C. Lee 《Journal of pest science》2018,91(4):1269-1278
Drosophila suzukii is widely studied because of its status as a global pest of berries and soft fruits. Environmental conditions and access to food resources impact the physiology and fitness of D. suzukii; these factors could also affect dispersal. Flight mills are a convenient tool for measuring and comparing the flight performance of insects. In this study, two experiments examined the effects of diet and humidity on D. suzukii flight performance using custom-built flight mills, and a third experiment compared the energy reserves of D. suzukii flown or not flown on flight mills. Over all flight assays, the median flight distance and duration were 27.16 m and 2.37 min, respectively, and the mean flight velocity was 0.18 m/s. The maximum flight distance and duration by an individual were 1.75 km and 2.35 h, respectively. Drosophila suzukii provisioned with blossoms, fruits, or standard laboratory diets flew farther distances and longer durations than starved flies. While starvation was associated with reduced flight performance, there were no observed differences between diet types. It remains unclear whether D. suzukii consistently use lipids, glycogen, sugar, or another energy source for flight because tethered individuals may not have flown enough to deplete energy reserves. Humidity did not affect flight performance of D. suzukii within a?~?2 h test period. These data indicate that most D. suzukii are likely to remain within limited area (e.g., within a field) but that some individuals can disperse long distances (field to field spread). 相似文献
783.
Heather L. Matthees Yangbo He Rachel K. Owen David Hopkins Bob Deutsch John Lee 《Communications in Soil Science and Plant Analysis》2017,48(18):2148-2154
Since 1954, the electrical conductivity of the saturated paste extract (ECe) has been the preferred index for soil salinity. Based on this value, remediation strategies were developed and widely used but this approach is time consuming and not routinely offered by many soil testing facilities. However, many laboratories determine the EC1:1 value of a 1:1 soil to solution ratio extract. The objective of this study was to identify the relationship between ECe and EC1:1 and determine if EC1:1 can be used as a proxy in the northern Great Plains for ECe. Samples were collected across five studies and from AGVISE Laboratory. The samples were analyzed for EC1:1 and ECe. The relationship between the ECe and EC1:1 showed that soil parent materials need to be considered in the conversion of EC1:1 values to ECe values. A failure to consider parent materials in this conversion may have short and long-term sustainability ramifications. 相似文献
784.
785.
The depolymerization of individual high and low molecular weight (HMW and LMW, respectively) glutenin subunits (GS) from the glutenin macropolymer (GMP) in doughs during mixing was investigated by reversed-phase (RP) HPLC and SDS-PAGE. Cultivars with different dough strengths, as well as lines null for specific HMW-GS and biotypes differing at individual HMW-GS and LMW-GS encoding loci, were studied. During mixing, the proportion of total HMW-GS in GMP decreased, and the ratios of different subunits in the GMP in doughs changed. There was a loss of chromosome 1B- and 1D-encoded x-HMW-GS, while the relative proportions of y-HMW-GS (among HMW-GS) increased. Changes in 1B subunits occurred first, while most of the changes in 1D HMW-GS content occurred during dough breakdown. Changes were more pronounced for doughs of weak to average strengths than for stronger doughs. RP-HPLC analysis demonstrated a consistent increase in the retention times (surface hydrophobicity) of chromosome 1D-encoded HMW-GS but not of other HMW-GS or LMW-GS during mixing. SDS-PAGE and RP-HPLC demonstrated that specific B subunits, typically those with lower hydrophobicity, were selectively depolymerized from the GMP during dough breakdown, while the proportions of specific C subunits, typically those with greater hydrophobicity, increased. Similar trends were seen in analyses of several pairs of biotypes differing at single LMW-GS encoding loci, although there were slight differences in the depolymerization behavior of wheats with different allelic compositions. The results suggest that dough breakdown may be triggered by the loss of specific HMW-GS from the GMP, and a structural hierarchy may exist for different LMW-GS within glutenin in doughs. 相似文献
786.
Fish Physiology and Biochemistry - The presence of perfluoroalkyl substances (PFASs) in the environment, especially in aquatic ecosystems, continues to be a significant concern for human and... 相似文献