全文获取类型
收费全文 | 255篇 |
免费 | 30篇 |
专业分类
林业 | 9篇 |
农学 | 49篇 |
基础科学 | 2篇 |
65篇 | |
综合类 | 16篇 |
农作物 | 15篇 |
水产渔业 | 29篇 |
畜牧兽医 | 80篇 |
园艺 | 4篇 |
植物保护 | 16篇 |
出版年
2023年 | 2篇 |
2022年 | 3篇 |
2021年 | 7篇 |
2020年 | 4篇 |
2019年 | 11篇 |
2018年 | 15篇 |
2017年 | 10篇 |
2016年 | 7篇 |
2015年 | 7篇 |
2014年 | 7篇 |
2013年 | 19篇 |
2012年 | 10篇 |
2011年 | 12篇 |
2010年 | 13篇 |
2009年 | 8篇 |
2008年 | 17篇 |
2007年 | 18篇 |
2006年 | 8篇 |
2005年 | 5篇 |
2004年 | 11篇 |
2003年 | 11篇 |
2002年 | 11篇 |
2001年 | 6篇 |
2000年 | 10篇 |
1999年 | 5篇 |
1998年 | 8篇 |
1997年 | 4篇 |
1996年 | 4篇 |
1995年 | 3篇 |
1994年 | 3篇 |
1993年 | 2篇 |
1992年 | 5篇 |
1991年 | 5篇 |
1990年 | 1篇 |
1989年 | 1篇 |
1988年 | 1篇 |
1987年 | 1篇 |
1986年 | 1篇 |
1985年 | 1篇 |
1983年 | 1篇 |
1981年 | 2篇 |
1978年 | 1篇 |
1974年 | 1篇 |
1973年 | 3篇 |
排序方式: 共有285条查询结果,搜索用时 31 毫秒
91.
Hoegh-Guldberg O Ortiz JC Dove S 《Science (New York, N.Y.)》2011,334(6062):1494-5; author reply 1495-6
92.
93.
Oxidative autoactivation of latent collagenase by human neutrophils 总被引:32,自引:0,他引:32
The pathological destruction of collagen plays a key role in the development of inflammatory disease states affecting every organ system in the human body. Neutrophils localized at inflammatory sites can potentially degrade collagen by releasing a metalloenzyme, collagenase, which is stored in a latent inactive form. Triggered human neutrophils were shown to release and simultaneously activate their latent collagenase. The activation of the latent enzyme was coupled to an oxidative process that required the generation of a highly reactive oxygen metabolite, hypochlorous acid. Oxidative regulation of latent collagenase activity may be important in the pathogenesis of connective tissue damage in vivo. 相似文献
94.
Summary Nine 2x clones with different genetic backgrounds and 2n pollen production by first division restitution (FDR) were each mated
with five 4x females in a linextester design. Estimates of both general combining ability (GCA) and specific combining ability
(SCA) were significant for tuber yield, among female and male parents. Four FDR clones with similar genetic background (half-sibs)
showed significantly different GCA for total yield, illustrating the importance of progeny testing for FDR clones before their
utilization as progenitors. A stronger influence of the 2x parents, compared to that of the 4x parents, on the performance
of the hybrids was observed for characters studied. The significance of male and female interactions for characters other
than tuber yield reinforced the importance of careful choice of the male and female parents for improving horticultural traits
of 4x–2x progenies. 相似文献
95.
Hoffmann M Hilton-Taylor C Angulo A Böhm M Brooks TM Butchart SH Carpenter KE Chanson J Collen B Cox NA Darwall WR Dulvy NK Harrison LR Katariya V Pollock CM Quader S Richman NI Rodrigues AS Tognelli MF Vié JC Aguiar JM Allen DJ Allen GR Amori G Ananjeva NB Andreone F Andrew P Aquino Ortiz AL Baillie JE Baldi R Bell BD Biju SD Bird JP Black-Decima P Blanc JJ Bolaños F Bolivar-G W Burfield IJ Burton JA Capper DR Castro F Catullo G Cavanagh RD Channing A Chao NL Chenery AM Chiozza F Clausnitzer V 《Science (New York, N.Y.)》2010,330(6010):1503-1509
Using data for 25,780 species categorized on the International Union for Conservation of Nature Red List, we present an assessment of the status of the world's vertebrates. One-fifth of species are classified as Threatened, and we show that this figure is increasing: On average, 52 species of mammals, birds, and amphibians move one category closer to extinction each year. However, this overall pattern conceals the impact of conservation successes, and we show that the rate of deterioration would have been at least one-fifth again as much in the absence of these. Nonetheless, current conservation efforts remain insufficient to offset the main drivers of biodiversity loss in these groups: agricultural expansion, logging, overexploitation, and invasive alien species. 相似文献
96.
Claxton JR Sutherst J Ortiz P Clarkson MJ 《Veterinary journal (London, England : 1997)》1999,157(2):166-171
The experiment aimed to measure the effect of constant and variable temperatures on the growth of Lymnaea viatrix snails, on the development of a Peruvian isolate of Fasciola hepatica eggs and on the development of F. hepatica in the snails. This was carried out by cultivating infected and uninfected snails and fluke eggs in artificial, temperature controlled chambers. L. viatrix snails were found to develop at a rate dependent on environmental temperature, but developed at least as well under conditions of varying temperature as at the same mean constant temperature. F. hepatica eggs held at constant or varying temperatures, developed at a rate comparable to other reports. However, eggs developing at varying temperatures appeared to have reduced hatchability. Parasite development within the snails was slow, though within the limits calculated from the literature, and varying temperature did not appear to reduce development compared to constant temperatures. 相似文献
97.
98.
Tiny Motlhaodi Mulatu Geleta Stephen Chite Moneim Fatih Rodomiro Ortiz Tomas Bryngelsson 《Genetic Resources and Crop Evolution》2017,64(3):599-610
Cultivated sorghum [Sorghum bicolor (L.) Moench] is an important food security crop in the semi-arid regions of the world including Asia and Africa. Its genetic diversity is contained mostly in traditional varieties and modern cultivars used by farmers. In this study, agro-morphological traits and molecular markers were used to assess genetic diversity in 22 accessions of cultivated sorghum from five countries (Botswana, Namibia, Swaziland, Zambia and Zimbabwe) in the Southern African Development Community (SADC) region. The study revealed a significant variation among 22 accessions in both qualitative and quantitative morphological traits, indicating the accessions’ promising potential as breeding material. For molecular analysis, 11 microsatellite primer-pairs were used, and generated a total of 70 alleles across 20 accessions. Analysis of molecular variance revealed a high level of genetic variation; 67 % among the accessions and 10 % among the five countries. The patterns of genetic diversity and the relationships observed in this study should provide insights for genetic resource conservation and utilization of sorghum germplasm in the SADC region. 相似文献
99.
L.T. Ortiz A. Rebolé S. Velasco M.L. Rodríguez J. Treviño J.L. Tejedor C. Alzueta 《Aquaculture Nutrition》2013,19(4):475-482
The objectives of the present study were to investigate the effects of inulin and fructooligosaccharides (FOS) on growth performance, whole body and fillet chemical composition and intestinal microbiota of rainbow trouts reared under fish farming conditions. Trouts fed inulin‐ or FOS‐containing diets (5 and 10 g kg?1) exhibited significant (P = 0.030) body weight gain improvements compared with controls. An increase in gross energy (P = 0.044) and Ca content (P = 0.034) in the whole body of trouts was observed for prebiotic treatments. A decrease in crude protein content (P = 0.009) and a tendency to increase total lipid and gross energy contents (P = 0.090 and P = 0.069, respectively) were detected in the fillet tissue for prebiotic treatments. These results clearly indicate that inulin and FOS improved the intestinal absorption of Ca and that the increased amount was predominantly incorporated into bone tissue. Inulin reduced (P = 0.027) the intestinal population of Vibrio spp. in the distal region to such an extent that no viable counts were detected. The presence of Flavobacterium spp. was not detected in any group, and the numbers of Aeromonas spp., Pseudomonas spp. and Gram‐positive bacteria were not affected (P > 0.05). 相似文献
100.
Isaac Kofi Bimpong Baboucarr Manneh Bathe Diop Kanfany Ghislain Abdulai Sow Nana Kofi Abaka Amoah Glenn Gregorio Rakesh Kumar Singh Rodomiro Ortiz Marco Wopereis 《Euphytica》2014,200(1):45-60
Salinity is a major constraint affecting rice productivity in rainfed and irrigated agro-ecosystems. Understanding salinity effects on rice production at the reproductive stage could improve adaptation for this trait. Identifying quantitative trait loci (QTLs) controlling adaptation to salinity may also accelerate breeding rice germplasm for environments prone to this stress. We used the salt tolerant landrace ‘Hasawi’ as a donor parent to generate three F2 offspring (consisting each of 500 individuals) with three African cultivars (‘NERICA-L-19’, ‘Sahel 108’ and ‘BG90-2’) used as recipient parents (RP). The F2s and F2:3s were evaluated for grain yield and other traits in saline fields. Salinity caused reduction in all measured traits across the F2-derived offspring, e.g. grain yield reduced between 65 and 73 %, but some offspring had twice the RP’s grain yield. QTL analysis revealed 75 QTLs for different traits in all 3 genetic backgrounds (GBs): 24 of them were common among all the 3 GBs while 31 were noted in 2 GBs, and 17 in one GB. ‘Hasawi’ contributed on average 49 % alleles to these QTLs. Two yield and yield related QTLs (qGY11 and qTN11) common in all 3 GBs were mapped on the same chromosomal segment suggesting these QTLs might be stable across different GBs. Four other QTLs were strongly associated with salinity tolerance with peak marker RM419, representing a potential candidate for MAS due to high LOD score and relatively large effect QTLs. 相似文献