全文获取类型
| 收费全文 | 6163篇 |
| 免费 | 433篇 |
| 国内免费 | 2篇 |
专业分类
| 林业 | 536篇 |
| 农学 | 141篇 |
| 基础科学 | 51篇 |
| 1236篇 | |
| 综合类 | 785篇 |
| 农作物 | 267篇 |
| 水产渔业 | 606篇 |
| 畜牧兽医 | 2347篇 |
| 园艺 | 181篇 |
| 植物保护 | 448篇 |
出版年
| 2023年 | 51篇 |
| 2022年 | 87篇 |
| 2021年 | 177篇 |
| 2020年 | 188篇 |
| 2019年 | 232篇 |
| 2018年 | 242篇 |
| 2017年 | 192篇 |
| 2016年 | 217篇 |
| 2015年 | 177篇 |
| 2014年 | 259篇 |
| 2013年 | 381篇 |
| 2012年 | 434篇 |
| 2011年 | 514篇 |
| 2010年 | 271篇 |
| 2009年 | 260篇 |
| 2008年 | 400篇 |
| 2007年 | 406篇 |
| 2006年 | 336篇 |
| 2005年 | 300篇 |
| 2004年 | 293篇 |
| 2003年 | 292篇 |
| 2002年 | 210篇 |
| 2001年 | 54篇 |
| 2000年 | 46篇 |
| 1999年 | 65篇 |
| 1998年 | 49篇 |
| 1997年 | 27篇 |
| 1996年 | 25篇 |
| 1995年 | 24篇 |
| 1994年 | 31篇 |
| 1993年 | 28篇 |
| 1992年 | 34篇 |
| 1991年 | 30篇 |
| 1990年 | 20篇 |
| 1989年 | 29篇 |
| 1988年 | 25篇 |
| 1987年 | 11篇 |
| 1986年 | 14篇 |
| 1985年 | 12篇 |
| 1984年 | 20篇 |
| 1983年 | 9篇 |
| 1982年 | 11篇 |
| 1981年 | 12篇 |
| 1980年 | 11篇 |
| 1978年 | 6篇 |
| 1976年 | 8篇 |
| 1974年 | 6篇 |
| 1971年 | 6篇 |
| 1925年 | 6篇 |
| 1924年 | 6篇 |
排序方式： 共有6598条查询结果，搜索用时 187 毫秒
101.
102.
103.
104.
105.
106.
Lina Maria Correa E Ricardo D. Moreno José Luis Riveros 《Anatomia, histologia, embryologia》2023,52(2):336-340
This is the first morpho-histological comparison of guanaco ovaries between reproductive (long-days) and non-reproductive (short-days) seasons, and oestrogen receptor-alpha (ERα) and beta (ERβ) detection. Different stages of follicle development were found in the cortical area, but no corpus luteum was detected. The size and frequency of antral follicles and large atretic follicles were higher in long-day ovaries than short-days, consistent with ovarian activity in this season. Differential expression of ERα and ERβ was observed in follicles at different stages of development between short and long days. These data reveal histological and molecular differences between reproductive and non-reproductive seasons of guanaco ovaries. 相似文献
107.
Nyland R. Falkenberg Giovanni Piccinni J. Tom Cothren Daniel I. Leskovar Charlie M. Rush 《Agricultural Water Management》2007
The applicability of commercially available remote sensing instrumentation was evaluated for site-specific management of abiotic and biotic stress on cotton (Gossypium hirsutum L.) grown under a center pivot low energy precision application (LEPA) irrigation system. This study was conducted in a field where three irrigation regimes (100%, 75%, and 50% ETc) were imposed on areas of Phymatotrichum (root rot) with the specific objectives to (1) examine commercial remote sensing instrumentation for locating areas showing biotic and abiotic stress symptomology in a cotton field, (2) compare data obtained from commercial aerial infrared photography to that collected by infrared transducers (IRTs) mounted on a center pivot, (3) evaluate canopy temperature changes between irrigation regimes and their relationship to lint yield with IRTs and/or IR photography, and (4) explore the use of deficit irrigation and the use of crop coefficients for irrigation scheduling. Pivot-mounted IRTs and an IR camera were able to differentiate water stress among irrigation regimes. The IR camera distinguished between biotic (root rot) and abiotic (drought) stress with the assistance of groundtruthing. The 50% ETc regime had significantly higher canopy temperatures than the other two regimes, which was reflected in significantly lower lint yields when compared to the 75% and 100% ETc regimes. Deficit irrigation down to 75% ETc had no impact on lint yield, indicating that water savings were possible without reducing yield. 相似文献
108.
Regolin André Luis Oliveira-Santos Luiz Gustavo Ribeiro Milton Cezar Bailey Larissa Lynn 《Landscape Ecology》2021,36(9):2519-2533
Landscape Ecology - An understanding of species-habitat relationships is required to assess the impacts of habitat fragmentation and degradation. To date, habitat modeling in fragmented landscapes... 相似文献
109.
110.
Digestates vary in composition and studies regarding their impact on C and N dynamics in soils are scarce. The objective was to analyse the C and N dynamics of digestates originating from various substrates applied to a sandy Cambisol and a silty Anthrosol. In three laboratory experiments (4–6 weeks), the effects of digestate properties, N rate and water content were tested. Averaged over both soils, 21% of the C supplied was emitted as CO2. Potential NH3 emissions during the first week ranged between 6% and 12% of NH4+ present in the digestates. The emission factors in the sandy Cambisol were on average 1.2 and 2 times higher for CO2 and potential NH3, respectively, compared to the silty Anthrosol. Similarly, net nitrogen mineralization in the sandy Cambisol was approximately twice the N mineralized in the silty Anthrosol. Net nitrification was not influenced by soil texture or different digestates, but increased with increasing application rates and had highest values at 75% of water holding capacity. Our results indicate that the type of substrate input for anaerobic digestion influences the properties of the digestate and therefore the dynamics of C and N. However, soil texture can affect these dynamics markedly. 相似文献