全文获取类型
收费全文 | 597篇 |
免费 | 39篇 |
国内免费 | 12篇 |
专业分类
林业 | 45篇 |
农学 | 31篇 |
基础科学 | 3篇 |
95篇 | |
综合类 | 92篇 |
农作物 | 37篇 |
水产渔业 | 58篇 |
畜牧兽医 | 230篇 |
园艺 | 16篇 |
植物保护 | 41篇 |
出版年
2023年 | 4篇 |
2022年 | 8篇 |
2021年 | 15篇 |
2020年 | 17篇 |
2019年 | 14篇 |
2018年 | 15篇 |
2017年 | 16篇 |
2016年 | 18篇 |
2015年 | 22篇 |
2014年 | 24篇 |
2013年 | 33篇 |
2012年 | 38篇 |
2011年 | 34篇 |
2010年 | 31篇 |
2009年 | 28篇 |
2008年 | 40篇 |
2007年 | 35篇 |
2006年 | 25篇 |
2005年 | 34篇 |
2004年 | 31篇 |
2003年 | 26篇 |
2002年 | 11篇 |
2001年 | 21篇 |
2000年 | 19篇 |
1999年 | 9篇 |
1998年 | 8篇 |
1997年 | 5篇 |
1996年 | 6篇 |
1995年 | 5篇 |
1994年 | 3篇 |
1993年 | 2篇 |
1992年 | 3篇 |
1991年 | 4篇 |
1990年 | 3篇 |
1989年 | 3篇 |
1987年 | 2篇 |
1986年 | 4篇 |
1984年 | 2篇 |
1978年 | 2篇 |
1975年 | 5篇 |
1971年 | 2篇 |
1969年 | 3篇 |
1953年 | 1篇 |
1940年 | 1篇 |
1937年 | 2篇 |
1936年 | 1篇 |
1935年 | 1篇 |
1932年 | 1篇 |
1924年 | 1篇 |
1918年 | 1篇 |
排序方式: 共有648条查询结果,搜索用时 15 毫秒
91.
Giovani Greigh de Brito Eveline Teixeira Caixeta Ana Paula Gallina Eunize Maciel Zambolim Laércio Zambolim Valdir Diola Marcelo Elhers Loureiro 《Euphytica》2010,173(2):255-264
The most important disease of Coffea arabica is coffee leaf rust caused by the fungus Hemileia vastatrix. The purpose of this study was to characterize the inheritance of coffee resistance gene(s) to race II of this pathogen and
to identify and map molecular markers linked to this trait. Different populations were used: F2 (160 plants), BCr (20), and BCs (135), derived from a cross between the resistant genotype Híbrido de Timor UFV 427-15 and
the susceptible cultivar Catuaí Amarelo UFV 2143-236 (IAC 30). The segregation analysis showed that the resistance of Híbrido
de Timor to race II of the H. vastatrix is conferred by a single dominant gene. The amplification of 176 AFLP (Amplified fragment length polymorphism) primer combinations
using bulked segregant analysis (BSA) allowed the identification of three molecular markers linked to the resistance gene.
Genetic mapping of these three markers in the F2 population indicated that they are distributed on both sides, flanking the resistance gene. The markers E.CTC/M.TTT405 and
E.CGT/M.TGT300 were found linked to the resistance gene at 8.69 cM (LOD 18.91) and 25.10 cM (LOD 5.37), respectively, while
E.CCT/M.TTC230 was localized on the other side of the gene, at 20.50 cM (LOD 6.15). These markers are the first rust resistance
markers identified in Híbrido de Timor and can be useful for marker assisted selection in coffee breeding programs. 相似文献
92.
R. Inclán C. Uribe D. De La Torre D. M. Sánchez M. A. Clavero A. M. Fernández R. Morante A. Cardeña M. Fernández A. Rubio 《European Journal of Forest Research》2010,129(1):93-100
Understanding the spatial and temporal variation in soil respiration within small geographic areas is essential to accurately assess the carbon budget on a global scale. In this study, we investigated the factors controlling soil respiration in an altitudinal gradient in a southern Mediterranean mixed pine–oak forest ecosystem in the north face of the Sierra de Guadarrama in Spain. Soil respiration was measured in five Pinus sylvestris L. plots over a period of 1 year by means of a closed dynamic system (LI-COR 6400). Soil temperature and water content were measured at the same time as soil respiration. Other soil physico-chemical and microbiological properties were measured during the study. Measured soil respiration ranged from 6.8 to 1.4 μmol m?2 s?1, showing the highest values at plots situated at higher elevation. Q 10 values ranged between 1.30 and 2.04, while R 10 values ranged between 2.0 and 3.6. The results indicate that the seasonal variation of soil respiration was mainly controlled by soil temperature and moisture. Among sites, soil carbon and nitrogen stocks regulate soil respiration in addition to soil temperature and moisture. Our results suggest that application of standard models to estimate soil respiration for small geographic areas may not be adequate unless other factors are considered in addition to soil temperature. 相似文献
93.
M.G. Pennisi E. La Camera L. Giacobbe B.M. Orlandella V. Lentini S. Zummo M.T. Fera 《Research in veterinary science》2010,88(3):379-384
Bartonella henselae is considered an emerging pathogen of veterinary and medical interest that can be occasionally transmitted to humans. Cats are considered to be the only reservoir host for B. henselae. In this study, we used a nested-PCR assay to investigate the prevalence of B. henselae and Bartonella clarridgeiae DNA in peripheral blood samples, fine needle lymph node aspirate specimens and oral swabs from 85 cats in order to develop an easy diagnostic strategy for the selection of infection-free cats that are being considered as pets, especially for immunocompromised patients. Overall, molecular analysis showed that 71 cats (83.5%) tested PCR positive for the presence of B. henselae DNA. PCR amplification of DNA B. henselae produced positive products from lymph node aspirate specimens (62/85; 72.9%) similar to those obtained from blood samples (60/85; 70.6%) and higher than those from oral swabs (51/85; 60%) of cats. No PCR product was obtained for B. clarridgeiae. The simultaneous analysis of three different clinical samples in our study increased the diagnostic possibilities for B. henselae infection in the examined cats from 60–72.9% to 83.5%. Lymph node aspirates were found to be the most effective clinical samples for the detection of B. henselae and blood samples were the next best. Oral swab samples were used in this study with good results when considered in combination with blood and/or lymph node aspiration. The use of nested-PCR assay on these three clinical samples may enhance the diagnostic sensitivity for bartonellosis in cats irrespective of the clinical status of animals. 相似文献
94.
95.
96.
西芹与我县传统种植的本地芹相比,具有药味淡、纤维含量低、脆嫩、耐寒、适应性强、产量高等特点,而且生长旺盛、叶柄变大、营养丰实,有降压、健脑、清肠、利便的作用。 相似文献
97.
Phan Van Kiem Chau Van Minh Nguyen Tien Dat La Van Kinh Dan Thuy Hang Nguyen Hoai Nam Nguyen Xuan Cuong Hoang Thanh Huong Trinh Van Lau 《Fitoterapia》2010
Phytochemical investigation of the methanol extract of Tinospora cordifolia aerial parts led to the isolation of four new and seven known compounds. The structures of two new aporphine alkaloids, N-formylasimilobine 2-O-β-d-glucopyranosyl-(1 → 2)-β-d-glucopyranoside (tinoscorside A, 1) and N-acetylasimilobine 2-O-β-d-glucopyranosyl-(1 → 2)-β-d-glucopyranoside (tinoscorside B, 2), a new clerodane diterpene, tinoscorside C (3), and a new phenylpropanoid, sinapyl 4-O-β-d-apiofuranosyl-(1 → 6)-O-β-d-glucopyranoside (tinoscorside D, 6) were determined by extensive spectroscopic methods including FTICR-MS and 1D and 2D NMR. 相似文献
98.
99.
Low salinity increases survival,body weight and development in tadpoles of the Chinese edible frog Hoplobatrachus rugulosus 下载免费PDF全文
La‐iad Nakkrasae Sukpaporn Phummisutthigoon Narattaphol Charoenphandhu 《Aquaculture Research》2016,47(10):3109-3118
Water salinity affects survival, growth and metamorphosis of anuran tadpoles. Hoplobatrachus rugulosus is considered not only as a freshwater amphibian but is also found in brackish wetlands. However, whether salinity change interferes with hatching, survival, body mass and development of H. rugulosus tadpoles is unknown. We found that salinity levels of <4‰ did not affect of survival or hatching of H. rugulosus eggs. At an early larval stage, tadpoles could tolerate up to 9‰ salinity for 96 h; however, body water content decreased when salinity was >5‰. After a 3‐week experiment, body weights of tadpoles exposed to 2‰ and 4‰ salinities were higher but that of the 6‰ group was lower compared with the 0‰ group. More than 90% of tadpoles exposed to 2‰ and 4‰ salinity showed complete metamorphosis. Salinity levels <4‰ promoted survival of tadpoles better than 0‰, whereas none of tadpoles in the 6‰ group became juvenile frogs in 50 days. Time taken to reach metamorphosis was shorter for 2‰ and 4‰ (47.22 ± 0.28 and 47.26 ± 0.33 days, respectively) than for 0‰ (49.31 ± 0.35 days). Juvenile frogs in the 2‰ group had greater body weight than the control. It could be concluded that salinity of <4‰ increased survival and body weight of H. rugulosus tadpoles, and shortened the time taken to reach metamorphosis. 相似文献
100.