全文获取类型
收费全文 | 142篇 |
免费 | 2篇 |
专业分类
林业 | 2篇 |
农学 | 4篇 |
15篇 | |
综合类 | 33篇 |
农作物 | 11篇 |
水产渔业 | 9篇 |
畜牧兽医 | 58篇 |
园艺 | 4篇 |
植物保护 | 8篇 |
出版年
2024年 | 1篇 |
2021年 | 4篇 |
2020年 | 3篇 |
2019年 | 2篇 |
2018年 | 2篇 |
2017年 | 2篇 |
2016年 | 1篇 |
2015年 | 1篇 |
2014年 | 2篇 |
2013年 | 3篇 |
2012年 | 7篇 |
2011年 | 6篇 |
2010年 | 2篇 |
2009年 | 6篇 |
2008年 | 6篇 |
2007年 | 13篇 |
2006年 | 3篇 |
2005年 | 4篇 |
2004年 | 5篇 |
2003年 | 3篇 |
2002年 | 8篇 |
2001年 | 4篇 |
2000年 | 3篇 |
1999年 | 4篇 |
1998年 | 1篇 |
1996年 | 1篇 |
1995年 | 2篇 |
1992年 | 3篇 |
1991年 | 2篇 |
1990年 | 3篇 |
1988年 | 4篇 |
1987年 | 2篇 |
1986年 | 1篇 |
1985年 | 3篇 |
1984年 | 2篇 |
1982年 | 4篇 |
1979年 | 1篇 |
1978年 | 3篇 |
1977年 | 1篇 |
1975年 | 1篇 |
1973年 | 1篇 |
1972年 | 1篇 |
1971年 | 3篇 |
1970年 | 1篇 |
1968年 | 1篇 |
1967年 | 3篇 |
1966年 | 1篇 |
1955年 | 3篇 |
1945年 | 1篇 |
排序方式: 共有144条查询结果,搜索用时 171 毫秒
141.
Kevin W. Staples Yong Chen David W. Townsend Damian C. Brady 《Fisheries Oceanography》2019,28(4):468-485
This study uses the Maine Department of Marine Resources Lobster Sea Sampling data (2000–2016) and logistic models to develop the first time series for the timing and suddenness of onset of the initial intra‐annual molt of American lobster in the Gulf of Maine (GoM), an annual fishery recruitment event crucial to fishermen. Data from three GoM regions (eastern, central, and western coastal Maine) were further divided by sex and estimated maturity of sampled lobsters for analysis. We found differences in the patterns of initial molt timing and suddenness between the regions, sexes, and stages of maturity. Using the Northeast Coastal Ocean Forecasting System hindcast temperatures, seasonal accumulated degrees above 5°C were used to describe the thermal history for each region at ocean depths of about 5 and 110 m. These temperature metrics were used in generalized linear models to investigate the potential effects of seasonal temperatures on the initial molt season. Results showed that initial intra‐annual molting of lobsters was variable from 2000 to 2016, with periods of both earlier and more sudden molts and later and more protracted molts. Warmer temperatures, specifically inshore temperatures, were generally associated with an earlier molt, but without complete uniformity in the direction and magnitude across seasons, regions, and lobster demographics. We also discuss why developing molt time series and quantifying the connection to the bottom temperatures are necessary and emphasized why existing monitoring programs and the applied quantification techniques herein make this relationship difficult to quantify. 相似文献
142.
143.
Bougainvillea spectabilis Willd. is of prime importance for horticulture, as well as potentially for pharmaceutical industries, agriculture and environmental industries. However, its floral development is not yet well understood. A detailed study on floral structure and floral organography in the species was first completed using microscopy of paraffin microtome sections of buds. The results were indicated as follows: first, the three trumped flowers in the cymose inflorescence develop asynchronously. Secondly, Varieties with multi-whorl bracts do not develop any sexual organs, i.e., perianth, pistil and stamens. Thirdly, the wall of the two-loculus anther consists of two kinds of cells: the inner wall, consisting of thick-cytoplasmed cells and the outer wall, consisting of fibrous cells. Fourthly, the pollen grains, with three germination colpi, vary substantially in the form and size in summer under the highest day temperature of 40 °C. Fifthly, the pistil is characterized with betalain-acumulating stylar brush. Followed the developmental course, only one basal ovule is developed in the superior ovary. Finally, organs of one flower develop consecutively from the outer to the inner, i.e., from bracts, to calyx, stamen, and carpel while the three flowers bloomed one by one in one cymose inflorescence. It almost takes 1 week from first bud to the third flower blooming. Our research showed a series of special characteristics of reproduction organography of B. spectabilis which can be useful for understanding its reproduction biology and its sterility. 相似文献
144.
Soft white and club wheat (Triticum aestivum L.) market subclasses have specific end-use characteristics. Among the most important of these characteristics are weak dough mixing and handling properties as a result of weak gluten. The SDS sedimentation test has gained wide acceptance as a useful, small-scale test in bread wheat breeding programs to predict gluten strength and baking quality. To optimize its use for soft white or club wheat breeding, variations of the SDS sedimentation test were performed on grain from winter wheats grown at eight locations in the U.S. Pacific Northwest, and the effects of lines, environment, and their interactions on SDS sedimentation volumes were determined. Using different sample weights and substituting whole meal for flour did not affect the ability of the SDS sedimentation test to differentiate among lines. Changes in protein concentration and sample weight caused proportional changes in SDS sedimentation volumes; however, the response was not consistent among all lines. Line had a greater effect on the SDS sedimentation volumes than any other source of variation. If differential effects of protein to SDS sedimentation among lines are taken into account, the SDS sedimentation test should be an effective small-scale test for end-use quality assessment in soft white and club wheat breeding programs. 相似文献