全文获取类型
收费全文 | 6744篇 |
免费 | 3377篇 |
专业分类
林业 | 199篇 |
农学 | 437篇 |
1361篇 | |
综合类 | 25篇 |
农作物 | 130篇 |
水产渔业 | 2545篇 |
畜牧兽医 | 4122篇 |
园艺 | 8篇 |
植物保护 | 1294篇 |
出版年
2023年 | 4篇 |
2022年 | 24篇 |
2021年 | 166篇 |
2020年 | 497篇 |
2019年 | 1035篇 |
2018年 | 918篇 |
2017年 | 952篇 |
2016年 | 948篇 |
2015年 | 819篇 |
2014年 | 814篇 |
2013年 | 986篇 |
2012年 | 476篇 |
2011年 | 489篇 |
2010年 | 607篇 |
2009年 | 262篇 |
2008年 | 241篇 |
2007年 | 84篇 |
2006年 | 111篇 |
2005年 | 95篇 |
2004年 | 111篇 |
2003年 | 92篇 |
2002年 | 107篇 |
2001年 | 72篇 |
2000年 | 103篇 |
1999年 | 12篇 |
1998年 | 4篇 |
1997年 | 11篇 |
1996年 | 5篇 |
1995年 | 7篇 |
1994年 | 5篇 |
1993年 | 6篇 |
1991年 | 2篇 |
1990年 | 7篇 |
1989年 | 5篇 |
1988年 | 2篇 |
1986年 | 3篇 |
1983年 | 2篇 |
1982年 | 3篇 |
1980年 | 2篇 |
1978年 | 6篇 |
1977年 | 5篇 |
1976年 | 1篇 |
1975年 | 3篇 |
1974年 | 2篇 |
1973年 | 1篇 |
1970年 | 4篇 |
1968年 | 1篇 |
1966年 | 1篇 |
1963年 | 1篇 |
1941年 | 2篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
52.
L.A. García‐Cortés A. Legarra M.A. Toro 《Zeitschrift für Tierzüchtung und Züchtungsbiologie》2014,131(2):97-104
The genetic relationship among individuals at one locus is characterized by nine coefficients of identity. The coefficients of inbreeding, coancestry and dominance (or fraternity) are just linear functions of them. Here, it is shown how they can be estimated using biallelic and triallelic markers using the method of moments, and comparisons are made with other methods based on molecular coancestry or molecular covariance. It is concluded that in the general case of dominance and inbreeding with biallelic markers, only the coefficients of inbreeding and coancestry can be estimated, but neither the single coefficients of identity nor the coefficient of dominance can be estimated. More than two alleles are required for a full estimation as illustrated with the triallelic situation. 相似文献
53.
54.
55.
C. Eckstein F. Guscetti M. Roos J. Martín de las Mulas B. Kaser‐Hotz C. Rohrer Bley 《Veterinary and comparative oncology》2009,7(1):54-68
We retrospectively evaluated predictive prognostic factors in 73 cats with vaccine‐associated sarcoma given postsurgical curative (n = 46, most with clean margins) or coarse fractionated radiotherapy (n = 27, most with either macroscopic disease or dirty margins). The former animals displayed a median survival of 43 months and a median progression free interval (PFI) of 37 months, the latter reached a median survival of 24 months and a median PFI of 10 months. In cats undergoing coarse fractionated therapy, factors predictive of a better outcome included lack of visible mass (n = 10) as opposed to macroscopic disease (n = 17, survival: 30 versus 7 months, P = 0.025; PFI: 20 versus 4 months, P = 0.01), adjuvant chemotherapy for gross disease (n = 5/17, survival: 29 versus 5 months, P = 0.04) and a smaller number of surgeries preceding radiation therapy (coeff = 0.41, P = 0.03). The Ki67 index was not predictive for survival. We concluded that postsurgical curative and coarse fractionated radiotherapy are effective legitimate options for managing vaccine‐associated sarcomas. 相似文献
56.
A. Pellegrini‐Masini I. Rodriguez Hurtado A. J. Stewart T. J. Divers 《Equine Veterinary Education》2009,21(2):79-84
Venous air embolism was suspected in 3 hospitalised horses on the basis of an inadvertently open jugular venous line. Subsequently the 3 horses developed clinical signs including cardiovascular collapse, cardiac dysrhythmia, pulmonary oedema, behavioural abnormalities and neurological signs consistent with central nervous system injury. Treatment included intranasal oxygen therapy, i.v. fluid administration and anti‐inflammatory therapy. Specific therapy aimed at treating air embolism in man is reviewed, with pertinent therapy potentially applicable to horses emphasised. 相似文献
57.
G. N⊘rgaard‐Nielsen 《British poultry science》1990,31(1):81-89
1. Observations of vigorous wing movements and measurements of bone strength were compared in two experiments with birds in three different housing systems: a semi-intensive alternative system under development, a battery cage system and a deep-litter system. 2. A significant effect of housing system on the frequency of vigorous wing movements was found. The highest frequency was seen in the deep-litter system, about half this number in the alternative system, while in the battery cages they were never observed. 3. Corresponding to this a reduction in humerus strength of 9% was found in hens from the alternative system and of 45% in hens from cages, compared with deep-litter. A reduction in tibial breaking strength was also found in caged hens, when compared to deep-litter hens. 4. Keeping hens in cages thus restricts their movements, especially wing movements, to the degree that bone strength is greatly reduced. 5. This has welfare implications, for hens with low bone breaking strength risk a possibility of breakage, especially when handled and transported. When alternative systems are designed opportunities for movement in the three dimensions should be considered. 相似文献
58.
Costa Olmar Antônio Denardin Ferreira Otoniel Geter Lauz Henrique Douglas Sampaio Vaz Ricardo Zambarda Fluck Ana Carolina Paris Wagner Kröning Alexsandro Bahr Griffith Luis Alberto Alonzo Matos Oscar Ivan Tuz 《Tropical animal health and production》2020,52(2):547-554
Tropical Animal Health and Production - The aim was to monitor the growth, the dry mass accumulation curve, and the structural photosynthetic components of forage peanut pasture, in different... 相似文献
59.
Robles Jimenez Lizbeth E. Ruiz Perez Jose A. Nicolas Di Lorenzo Chay Canul Alfonso J. Ramirez-Rivera Julio Cesar Villegas-Estrada Daniela Vargas-Bello-Pérez Einar Gonzalez-Ronquillo Manuel 《Tropical animal health and production》2020,52(3):1257-1267
Tropical Animal Health and Production - Currently for the reduction of methane (CH4) emissions are using fodder rich in condensed tannins, however, not yet known exactly how they act in the rumen... 相似文献
60.
M. Koivula M.‐L. Sevón‐Aimonen I. Strandén K. Matilainen T. Serenius K.J. Stalder E.A. Mäntysaari 《Zeitschrift für Tierzüchtung und Züchtungsbiologie》2008,125(3):168-175
This paper's objectives were to estimate the genetic (co)variance components of the Gompertz growth curve parameters and to evaluate the relationship of estimated breeding values (EBV) based on average daily gain (ADG) and Gompertz growth curves. Finnish Yorkshire central test station performance data was obtained from the Faba Breeding (Vantaa, Finland). The final data set included 121,488 weight records from 10,111 pigs. Heritability estimates for the Gompertz growth parameters mature weight (alpha), logarithm of mature weight to birth weight ratio (beta) and maturation rate (kappa) were 0.44, 0.55 and 0.31, respectively. Genotypic and phenotypic correlations between the growth curve parameters were high and mainly negative. The only positive relationship was found between alpha and beta. Pearson and Spearman rank correlation coefficients between EBV for ADG and daily gain calculated from Gompertz growth curves were 0.79. The Spearman rank correlation between the sire EBV for ADG and Gompertz growth curve parameter-based ADG for all sires with at least 15 progeny was 0.86. Growth curves differ significantly between individuals and this information could be utilized for selection purposes when improving growth rate in pigs. 相似文献