全文获取类型
收费全文 | 589篇 |
免费 | 66篇 |
国内免费 | 2篇 |
专业分类
林业 | 14篇 |
农学 | 28篇 |
基础科学 | 2篇 |
105篇 | |
综合类 | 35篇 |
农作物 | 26篇 |
水产渔业 | 44篇 |
畜牧兽医 | 349篇 |
园艺 | 13篇 |
植物保护 | 41篇 |
出版年
2023年 | 5篇 |
2022年 | 4篇 |
2021年 | 12篇 |
2020年 | 18篇 |
2019年 | 21篇 |
2018年 | 35篇 |
2017年 | 14篇 |
2016年 | 23篇 |
2015年 | 21篇 |
2014年 | 29篇 |
2013年 | 48篇 |
2012年 | 11篇 |
2011年 | 28篇 |
2010年 | 30篇 |
2009年 | 25篇 |
2008年 | 38篇 |
2007年 | 23篇 |
2006年 | 36篇 |
2005年 | 21篇 |
2004年 | 26篇 |
2003年 | 16篇 |
2002年 | 17篇 |
2001年 | 15篇 |
2000年 | 16篇 |
1999年 | 16篇 |
1998年 | 20篇 |
1997年 | 13篇 |
1996年 | 16篇 |
1995年 | 13篇 |
1994年 | 4篇 |
1993年 | 4篇 |
1992年 | 8篇 |
1991年 | 3篇 |
1990年 | 2篇 |
1989年 | 5篇 |
1988年 | 6篇 |
1986年 | 4篇 |
1985年 | 1篇 |
1983年 | 1篇 |
1977年 | 1篇 |
1975年 | 2篇 |
1974年 | 1篇 |
1973年 | 3篇 |
1972年 | 2篇 |
排序方式: 共有657条查询结果,搜索用时 15 毫秒
31.
FJ Pena JA Gines J Duque V Vieitez R Martinez –Pérez L Madejón I Nuñez Martinez JM Moran S Fernández-García 《Reproduction in domestic animals》2006,41(2):189-190
A 6-year-old female Alaska Malamute dog was presented for evaluation of abdominal enlargement referred by a local veterinarian. On the history, the owner complained of chronic abdominal enlargement initiated more than 4 months ago, reduced appetite, occasional vomiting and general dullness. He also complained of greenish mucous intermittent vaginal discharge starting 10 days ago. The bitch was chronically treated with medroxiprogesterone acetate. A laparatomy was performed and fluid in the abdomen was found and aspirated during the surgery. Also a very fluid-filled distended uterus and a mass in the distal part of the left uterine horn were found. The mass was encapsulated by the omentum, but areas of necrosis and calcification were identified. Histopathological diagnosis was endometrial adenocarcinoma. 相似文献
32.
S Ikeda JM Prendes C Alonso-Montes A Rodríguez C Díez M Kitagawa H Imai E Gómez 《Reproduction in domestic animals》2006,41(5):383-385
In multiple ovulation and embryo transfer (MOET) programmes in cattle, a considerable number of morphologically poor-quality embryos continue to be produced; this is one of the limiting factors of the technique. Apoptosis has often been implicated in developmental arrest and fragmentation; these are regarded as poor traits of embryonic quality in mammalian pre-implantation embryos. In the present study, apoptosis was assessed in morphologically poor-quality embryos in comparison with good-quality embryos that were recovered from a MOET programme. Retarded embryos (two to 16 cell stage), morulae with severe fragmentation and morphologically good-quality morulae recovered from superstimulated cows at day 7 post-insemination were subjected to TdT-mediated dUTP nick-end labelling (TUNEL) and Hoechst staining. Cell nuclei that showed both TUNEL staining and apoptotic morphology were considered to be apoptotic. Apoptotic index (AI) was calculated as the percentage of apoptotic cells per embryo. Fifteen of 17 retarded embryos and 10 of 15 morphologically poor-quality morulae did not show signs of apoptosis. The mean AIs in the morphologically poor-quality embryos (two to 16 cell stage, 2.2%; poor morulae, 1.3%) were as low as that in the good-quality embryos (2.9%). These results suggest that another mode of developmental arrest and/or fragmentation that is independent of apoptosis occurs in morphologically poor-quality embryos recovered from MOET programmes. 相似文献
33.
34.
35.
Eduardo Segundo Dietrich E. Lesemann Germán Martín María P. Carmona Leticia Ruiz Isabel M. Cuadrado Leonardo Velasco Dirk Janssen 《European journal of plant pathology / European Foundation for Plant Pathology》2007,117(1):81-87
Amaranthus leaf mottle virus (AmLMV) was classified as a member of the genus Potyvirus on the basis of its particle morphology, serology, and biological properties (Casetta et al., 1986). Based on these properties, an Amaranthus viridis-infecting virus isolated in Spain, causing mottle and leaf blistering as well as reduced growth has been identified as AmLMV.
The 3′ terminal genomic region of this and a reference isolate from Italy has been sequenced and reveals a 95% nucleotide
identity between the two isolates. The sequenced part comprises the coat protein with 281 amino acids and 315 nucleotides
of the 3′ untranslated region (UTR) preceding a polyadenylated tail. Pairwise comparisons and phylogenetic analysis of the
nucleotide and deduced amino acid sequences of the CP and 3′ UTR of the cloned cDNAs with those of other potyviruses shows
that AmLMV is a distinct potyvirus closely related to Potato virus Y. 相似文献
36.
AFLP profiles were generated from poplar leaf rust ( Melampsora larici-populina ) collected from Populus trichocarpa cv. Trichobel at six sites in the UK in 2001. Of a total of 145 isolates, 121 were unique AFLP phenotypes. On one occasion, the same AFLP phenotype was found at two sites. The analysis indicated that 81·88% of the total variation was attributable to differences among individuals within replicate plots, 3·47% to differences among plots within sites and 14·65% to differences among sites. Weir & Cockerham's θ was calculated as 0·138 and θ B , the Bayesian analogue of F ST , as 0·146. Overall, there was sufficient gene flow among different sites to prevent genetic drift, as Nm was calculated as 1·562 using θ and as 1·462 using θ B . Nei's genetic distance and population-assignment test indicated that the rust from a site in north-east England was differentiated from those from other sites. There was no significant correlation between genetic and geographical distances. The results indicate that sexual reproduction has a major influence on the relative lack of population structure of M. larici-populina in the UK. 相似文献
37.
38.
39.
Abecia José-Alfonso Barrio Antonio Ruiz José-Antonio 《Veterinary research communications》2022,46(2):609-612
Veterinary Research Communications - Twenty-five ewe-lambs born in November were used to measure the effect of the presence of cyclic or non-cyclic adult ewes on the age at first fertile estrus.... 相似文献
40.
Citrus response to salinity: growth and nutrient uptake 总被引:1,自引:0,他引:1
To determine the effects of salinity on relative growth rate (RGR), net assimilation rate on a leaf weight basis (NAR(w)), leaf weight ratio (LWR), and nutrient uptake and utilization of citrus, we grew four citrus rootstocks (sour orange, Cleopatra mandarin, Carrizo citrange and Citrus macrophylla) in nutrient solutions containing 0, 10, 20, 40 or 80 mM NaCl for 20, 40 or 60 days. For each element analyzed, specific absorption rate (SAR) and specific utilization rate on a leaf basis (SUR(L)) were calculated for the period between Days 40 and 60. Relative growth rate decreased with time for all treatments and rootstocks. Salt treatment significantly reduced both RGR and NAR(w), whereas LWR showed no definite trend. In all rootstocks, NAR(w), but not LWR, was significantly correlated with RGR, indicating that NAR(w) was an important factor underlying the salinity-induced differences in RGR among the citrus rootstocks. At Day 60, salinity had a significant effect on leaf concentrations of Cl, Na, K, Ca, Mg, P, Fe, Mn and Zn and on the SAR and SUR(L) of most elements. In general, RGR was correlated with SAR and SUR(L). Therefore, in addition to osmotic effects and the inhibitory effects of high concentrations of Cl(-) and Na(+), an imbalance of essential nutrients may also contribute to the reduction in plant growth under saline conditions. 相似文献