全文获取类型
收费全文 | 599篇 |
免费 | 55篇 |
国内免费 | 1篇 |
专业分类
林业 | 50篇 |
农学 | 28篇 |
基础科学 | 1篇 |
73篇 | |
综合类 | 94篇 |
农作物 | 19篇 |
水产渔业 | 49篇 |
畜牧兽医 | 281篇 |
园艺 | 11篇 |
植物保护 | 49篇 |
出版年
2024年 | 2篇 |
2023年 | 9篇 |
2022年 | 9篇 |
2021年 | 29篇 |
2020年 | 28篇 |
2019年 | 37篇 |
2018年 | 14篇 |
2017年 | 34篇 |
2016年 | 20篇 |
2015年 | 17篇 |
2014年 | 30篇 |
2013年 | 32篇 |
2012年 | 40篇 |
2011年 | 54篇 |
2010年 | 22篇 |
2009年 | 19篇 |
2008年 | 37篇 |
2007年 | 36篇 |
2006年 | 34篇 |
2005年 | 34篇 |
2004年 | 22篇 |
2003年 | 21篇 |
2002年 | 18篇 |
2001年 | 6篇 |
2000年 | 8篇 |
1999年 | 4篇 |
1998年 | 1篇 |
1997年 | 5篇 |
1996年 | 2篇 |
1995年 | 3篇 |
1994年 | 2篇 |
1993年 | 2篇 |
1992年 | 4篇 |
1991年 | 1篇 |
1990年 | 3篇 |
1986年 | 1篇 |
1985年 | 2篇 |
1984年 | 2篇 |
1983年 | 2篇 |
1978年 | 1篇 |
1977年 | 1篇 |
1975年 | 1篇 |
1971年 | 2篇 |
1969年 | 1篇 |
1948年 | 1篇 |
1898年 | 2篇 |
排序方式: 共有655条查询结果,搜索用时 0 毫秒
651.
Marcela Carvalho Andrade Alex Antônio da Silva Regis de Castro Carvalho Juliana de Andrade Santiago Alisson Marcel Souza de Oliveira David Merrill Francis Wilson Roberto Maluf 《Genetic Resources and Crop Evolution》2018,65(6):1671-1685
Pest resistance in Solanum galapagense has been associated with the presence of type IV glandular trichomes and allelochemicals. Knowledge of the genetic factors involved in determining the presence and type of trichomes may assist in the process of gene introgression for development of pest resistant tomato cultivars. In this study, we sought to identify QTLs associated with the presence of type IV trichomes in an F2 population derived from the interspecific cross of Solanum lycopersicum TOM-684?×?S. galapagense accession LA1401. Two QTLs contributing to type IV trichome occurrence and density were detected, one major QTL (gal.IV-2), responsible for 35.22% of phenotypic variation, was located on chromosome 2. The other QTL (gal.IV-3) was located on chromosome 3, and explained 23.35% of the phenotypic variation in the F2 population. These QTLs were responsible for 26.44 and 3.37% of the variation observed in a progeny derived from a backcross to TOM-684. The same QTLs were also associated with type II?+?III non-glandular trichomes, whose densities were negatively correlated to those of type IV trichomes, suggesting that the loci found may have pleiotropic effects for high type IV/low type II?+?III trichome densities. Our results indicate that the inheritance for type IV trichomes can be explained by a few genetic factors affecting the presence of a gland and the density of trichomes. These results further suggest a revision to trichome classification used for tomato may be appropriate. 相似文献
652.
653.
Effect of days postburning and calcium oxide on the fermentation,aerobic stability and nutritional characteristics of sugarcane silage for finishing Nellore steers
下载免费PDF全文
![点击此处可从《Grass and Forage Science》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Anna Paula T. P. Roth Gustavo R. Siqueira Carlos H. S. Rabelo Matheus H. Moretti Carla J. Härter Flávio D. Resende Ricardo A. Reis 《Grass and Forage Science》2018,73(3):671-684
In this study, the effects of days postburning and calcium oxide (CaO) on the fermentation, aerobic stability and nutritional characteristics of sugarcane silages for finishing Nellore steers were investigated. Silages were prepared in minisilos from in natura and burned sugarcane that remained in the field 1 and 10 days postburning (1‐day burned and 10‐day burned, respectively). Next, forages were left untreated or treated with CaO (10 g/kg fresh forage). Compared to that in untreated silages, CaO application increased the dry‐matter (DM) recovery of in natura, 1‐day and 10‐day burned silages (p < 0.001) by 67, 179 and 209 g/kg DM respectively. The CaO treatment increased (p < 0.001) the aerobic stability of the in natura and 10‐day burned silages by 62.7 and 24.7 hr respectively. In a feedlot experiment, feeding 1‐day burned silage reduced DM intake of steers throughout the feedlot period (0–93 days; p < 0.05) compared with that of steers fed in natura silage diet, but the average daily gain (ADG) was lower (p = 0.006) only during the adaptation period (?0.16 kg/day; 0–28 days). The CaO application decreased DM intake (p = 0.007; ?1.17 kg/day) and ADG (p < 0.001; ?0.13 kg/day) of steers only during the adaptation period likely owing to low silage palatability caused by increased Ca and butyric acid concentrations (≥11.6 g/kg DM). We recommend feeding beef cattle with CaO‐treated burned sugarcane silages in low‐dietary concentration because of its high butyric acid concentration. 相似文献
654.
Isela Rodríguez-Arévalo Efisio Mattana Lilia García Udayangani Liu Rafael Lira Patricia Dávila Alex Hudson Hugh W. Pritchard Tiziana Ulian 《Genetic Resources and Crop Evolution》2017,64(6):1141-1190
The efficient storage and germination of seeds underpin the effective use of plants for livelihoods and sustainable development. A total of 204 wild species useful for local communities of the Tehuacán–Cuicatlán Valley were collected and stored in seed banks in country for long term conservation, and 66 % (i.e., 134) duplicated in the U.K., as an effective means of ex situ conservation. Of the 204 species, 147 (122 of which also duplicated in the U.K.) were previously listed as useful plants in the ethnofloristic inventory of the Valley. Based on literature surveys, we found that one of the major impediments to the use of stored seeds of wild species is the lack of knowledge of how to germinate the seed. In detailed studies, we found that seeds of 18 useful plant species from 10 different families germinated readily and could be propagated. In contrast, four species (Actinocheita filicina, Bursera submoniliformis, Karwinskia mollis and Lippia graveolens) produced dormant seeds and therefore further studies are needed before their use can be maximised in large scale propagation programmes in support of conservation and livelihoods. Overall, this large-scale study on useful wild plant species in Mexico confirms that conventional seed banking can effectively support sustainable development and livelihood programmes. 相似文献
655.
- The coastal marine protected ecosystem at Punta Coles (as a part of the Reserva Nacional de Islas, Islotes y Puntas Guaneras) is located in a highly exploited area in southern Peru and contains several commercial, bioengineering and other benthic species.
- Pre-image population analysis was used to estimate the transient values of intrinsic growth rate (r) based on biomass and density time series as a proxy of productivity to assess the effectiveness of protection.
- The outcomes obtained showed that the gastropods Concholepas concholepas, Fissurella latimartiginata and the tunicate Purya chilensis showed a reduction of productivity during recent years, whilst the sea urchin Loxechinus albus, the barnacle Balanus laevis and the bivalve Semimytilus algosus showed an opposite pattern. Several species exhibited a chaotic dynamic, coinciding with the highest productivity values. In 2016 and 2017, several species exhibited a reduction of their abundance which could be delayed responses explained by changes in oceanographic conditions (reduction of coastal upwelling), La Niña event and illegal harvest.
- The above notwithstanding, the results suggest that effective protection of benthic species in the protected ecosystem of Punta Coles have been partially accomplished. Therefore, this work could be considered a baseline study, permitting the subsequent monitoring of productivity of the main species inhabiting the coastal area of Punta Coles.
- Pre-image population analysis could be used as a complimentary analytical tool since it enables the evaluation of transient population parameters (e.g. productivity) thus aiding population management, conservation and monitoring decisions.