全文获取类型
收费全文 | 270篇 |
免费 | 25篇 |
国内免费 | 1篇 |
专业分类
林业 | 41篇 |
农学 | 20篇 |
基础科学 | 1篇 |
38篇 | |
综合类 | 10篇 |
农作物 | 31篇 |
水产渔业 | 42篇 |
畜牧兽医 | 84篇 |
园艺 | 3篇 |
植物保护 | 26篇 |
出版年
2023年 | 3篇 |
2022年 | 2篇 |
2021年 | 15篇 |
2020年 | 7篇 |
2019年 | 12篇 |
2018年 | 18篇 |
2017年 | 17篇 |
2016年 | 15篇 |
2015年 | 11篇 |
2014年 | 15篇 |
2013年 | 15篇 |
2012年 | 16篇 |
2011年 | 24篇 |
2010年 | 21篇 |
2009年 | 10篇 |
2008年 | 16篇 |
2007年 | 8篇 |
2006年 | 14篇 |
2005年 | 8篇 |
2004年 | 10篇 |
2003年 | 9篇 |
2002年 | 4篇 |
2001年 | 7篇 |
2000年 | 3篇 |
1999年 | 1篇 |
1997年 | 1篇 |
1995年 | 1篇 |
1991年 | 3篇 |
1990年 | 1篇 |
1989年 | 1篇 |
1987年 | 1篇 |
1984年 | 1篇 |
1982年 | 1篇 |
1976年 | 2篇 |
1958年 | 1篇 |
1905年 | 2篇 |
排序方式: 共有296条查询结果,搜索用时 78 毫秒
91.
Van Ba Nguyen Nam Le Quang Do Duy Ngoc Van Hau Nguyen Pham Lan Doan 《Tropical animal health and production》2020,52(3):1033-1041
Tropical Animal Health and Production - The study aimed to characterize genetic diversity, genetic clusters, and phylogenetic relationships of 15 Vietnamese indigenous pig breeds across the country... 相似文献
92.
A cold-adapted porcine reproductive and respiratory syndrome virus (CA-VR2332) was generated from the modified live virus strain VR2332. CA-VR2332 showed impaired growth when cultured at 37°C with numerous mutations (S731F, E819D, G975E, and D1014N) in the hypervariable region of the NSP2, in which the mutation S731F might play a vital role in viral replication at 30°C. Conserved amino acid sequences of the GP5 protein suggests that CA-VR2332 is a promising candidate for producing an effective vaccine against PRRSV infection. Further studies on replication and immunogenicity in vivo are required to evaluate the properties of CA-VR2332. 相似文献
93.
In this study, one-cycle and multi-cycle culture systems for Artemia in seasonal salt ponds are compared. In one-cycle systems, Artemia is inoculated only once per season, while in multicycle systems ponds are drained and re-stocked several times per season. In Vietnam, three-cycle systems gave significantly higher cyst yields than did the one-cycle system. However, after two cycles, systems were not significantly different. Food limitation probably caused the steady decline in cyst yields, as observed in the one-cycle ponds. In these ponds, females have smaller broods (from the second cycle onwards) and during the last cycle the number of adult females is lower than in multi-cycle ponds. 相似文献
94.
Do Nascimento VV Castro HC Abreu PA Oliveira AE Fernandez JH Araújo Jda S Machado OL 《Journal of agricultural and food chemistry》2011,59(9):4814-4821
The major Ricinus communis allergens are the 2S albumins, Ric c 1 and Ric c 3. These proteins contain a trypsin/α-amylase inhibitor family domain, suggesting that they have a role in insect resistance. In this study, we verified that Ric c 1 and Ric c 3 inhibited the α-amylase activity of Callosobruchus maculatus, Zabrotes subfasciatus, and Tenebrio molitor (TMA) larvae as well as mammalian α-amylase. The toxicity of 2S albumin was determined through its incorporation in C. maculatus larvae as part of an artificial diet. Bioassays revealed that 2S albumin reduced larval growth by 20%. We also analyzed the tridimensional structures of Ric c 1 and Ric c 3 by (a) constructing a comparative model of Ric c 1 based on Ric c 3 NMR structure and (b) constructing the theoretical structure of the Ric c 1-TMA and Ric c 3-TMA complexes. Our biological and theoretical results revealed that Ric c 1 and Ric c 3 are a new class of α-amylase inhibitors. They could potentially be used to help design inhibitors that would be useful in diverse fields, ranging from diabetes treatment to crop protection. 相似文献
95.
Kim EJ Kwon J Park SH Park C Seo YB Shin HK Kim HK Lee KS Choi SY Ryu do H Hwang GS 《Journal of agricultural and food chemistry》2011,59(16):8806-8815
Angelica gigas obtained from different geographical regions was characterized using (1)H nuclear magnetic resonance (NMR) spectroscopy and ultraperformance liquid chromatography-mass spectrometry (UPLC-MS) followed by multivariate data analyses. Principal component analysis (PCA) and orthogonal partial least-squares-discriminant analysis (OPLS-DA) score plots from (1)H NMR and UPLC-MS data sets showed a clear distinction among A. gigas from three different regions in Korea. The major metabolites that contributed to the discrimination factor were primary metabolites including acetate, choline, citrate, 1,3-dimethylurate, fumarate, glucose, histamine, lactose, malate, N-acetylglutamate, succinate, and valine and secondary metabolites including decursin, decursinol, nodakenin, marmesin, 7-hydroxy-6-(2R-hydroxy-3-methylbut-3-ethyl)coumarin in A. gigas roots. The results demonstrate that (1)H NMR and UPLC-MS-based metabolic profiling coupled with chemometric analysis can be used to discriminate the geographical origins of various herbal medicines and to identify primary and secondary metabolites responsible for discrimination. 相似文献
96.
Dong Chil Chang Hwang Bae Sohn Ji Hong Cho Ju Sung Im Yong Ik Jin Gyeong Ran Do Su Jeong Kim Hyun Mook Cho Yong Beom Lee 《Potato Research》2014,57(2):99-110
The relationship between the severity of natural freezing and frost damage (FFD) and the observed growth recovery and field production of Superior potatoes (Solanum tuberosum L.) was investigated under screen house conditions. Potato plants were damaged by accidental freezing and frost during the early phase of shoot growth, 40 days after planting in highland summer crop areas in Korea. The observations of FFD were classified visually into “severe” (>75%), “moderate” (50%), “mild” (<25%), and “no FFD”, based on the percentage of the area of the shoots which was damaged. The early vegetative growth recovery, in terms of groundcover, was reduced as the level of FFD increased. At 28 days after a freezing and frost damage (DAFF), the potato plants with mild or no symptoms had produced more groundcover than the plants with moderate or severe symptoms. At 35 DAFF, groundcover was the same across all levels of severity, at nearly 100%. Despite the slower canopy development, plants with FFD achieved a higher fresh shoot weight and total chlorophyll content, whereas physiological growth indices such as photosynthetic rate and stomatal conductance of leaves were not different among levels of FFD at 60 DAFF. The number of lateral stems and days to tuberization increased significantly as the level of FFD increased; however, the harvest index, the number of tubers per plant, and seed tuber production were all reduced in plants with severe FFD. In addition, the tubers from plants with severe FFD had an increased ratio of length to width and 40% more tuber eyes than tubers from undamaged plants. The elongated tubers also showed an increase in cell division, demonstrated by higher numbers of cells in the cortical zones. The aforementioned measurements were obtained from natural event and led to a deduction that Superior has a capacity to recover from FFD, unless the plants were severely damaged (>75%) early in the season. 相似文献
97.
One novel banana fruit ripening related 1-aminocyclopropane-1-carboxylate (ACC) oxidase gene quite different from ACC oxidase genes from other species was cloned. In contrast to other studies, the polypeptide encoded by this gene, named Mh-ACO1, lacks the putative leucine zipper motif which is conserved in all known ACC oxidases including the other previously reported banana ACC oxidase, Mh-ACO2. The locus consists of two nearly identical paralogous ACC oxidase genes arranged in opposite orientation and separated by a 3.1-kb intergenic region. The has only two introns, at positions identical to , which comprises a coding region interrupted by three introns. The predicted amino acid sequence of Mh-ACO1 shares less than 50% identity to those of ACC oxidase from other climacteric fruits, while that of Mh-ACO2 shows more than 65% homology. When expressed in Saccharomyces cerevisiae -encoded protein possessed the enzyme activity for ethylene conversion. The levels of mRNA corresponding to both and increased during fruit ripening and were induced by exogenous ethylene. We conclude that both and contribute to increased ethylene production in fruits and these two genes are differentially expressed in fruits and other organs in banana. 相似文献
98.
Hye Min Jung Eun Mi Lee Byung Chul Ji Sung Ok Sohn Han Do Ghim Hyunju Cho Young A Han Jin Hyun Choi Jae Deuk Yun Jeong Hyun Yeum 《Fibers and Polymers》2006,7(3):229-234
Poly(vinyl acetate) (PVAc)/poly(vinyl alcohol)(PVA)/montmorillonite (MMT) clay nanocomposite microspheres with a core/shell
structure have been developed via a suspension polymerization approach. In order to prepare the PVAc/MMT and PVAc/PVA/MMT
nanocomposite microspheres, which are promising precursor of PVA/MMT nanocomposite microspheres, suspension polymerization
of vinyl acetate with organophilic MMT and heterogeneous saponification were conducted. A quaternary ammonium salt, cetyltrimethylammonium
bromide, was mixed with the MMT in the monomer phase prior to the suspension polymerization. The rate of conversion decreased
with an increase in MMT concentration. The incorporation of MMT into the PVAc was verified by FT-IR spectroscopy. Organic
vinyl acetate monomers were intercalated into the interlayer regions of organophilic clay hosts and followed by suspension
polymerization. Partially saponified PVA/MMT nanocomposite microspheres with a core/shell structure were successfully prepared
by heterogeneous saponification. 相似文献
99.
Young Hee Joung Jerry L. Hill Jung Oh Hyun Ding Mu Juchun Luo Do Hyung Lee Takayuki Kawahara Jeung Keun Suh Mark S. Roh 《林业研究》2013,24(1):53-60
To confirm a hybrid swarm population of Pinus densiflora × P. sylvestris in Jilin, China, we used needles and seeds from P. densiflora, P. sylvestris, and P. densiflora × P. sylvestris collected from natural stands or experimental stations to study whether shoot apex morphology of 4- year old seedlings can be correlated with the sequence of a chloroplast DNA simple sequence repeat marker (cpDNA SSRs). Total genomic DNA was extracted and subjected to sequence analysis of the pine cpDNA SSR marker Pt15169. Results show that morphological characters from 4-year old seedlings did not correlate with sequence variants of this marker. Marker haplotypes from all P. sylvestris trees had a CTAT element that was absent from all sampled P. densiflora trees. However, both haplotype classes involving this insertion/deletion element were found in a P. densiflora × P. sylvestris population and its seedling progeny. It was concluded that the P. densiflora × P. sylvestris accessions sampled from Jilin, China resulted from bi-directional crosses, as evidenced by both species’ cpDNA haplotypes within the hybrid swarm population. 相似文献
100.
Lan Doan Pham Duy Ngoc Do Nguyen Trong Binh Le Quang Nam Nguyen Van Ba Tran Thi Thu Thuy Tran Xuan Hoan Vu Chi Cuong Haja N. Kadarmideen 《Livestock Science》2013,155(1):17-22
Cattle play a very important role in agriculture and food security in Vietnam. A high level of cattle diversity exists and serves different needs of Vietnamese cattle keepers but has not yet been molecularly characterized. This study evaluates the genetic diversity and structure of Vietnamese indigenous cattle populations, using microsatellite markers. A total of 410 individuals from six indigenous cattle populations and an exotic breed was characterized using 27 microsatellite markers A total of 362 alleles was detected and the number of alleles per locus ranged from 8 (INRA005 and ILSTS005) to 17 (ETH185). The level of gene diversity was high indicated by a mean expected heterozygosity (He) across populations and loci of 0.73. Level of inbreeding (mean FIS=0.05) and genetic differentiation (mean FST=0.04) was moderate. The phylogenetic tree based on Reynolds genetic distance reflected geographic distances. Structure analysis indicated five homogeneous clusters. The Brahman, Lang Son, Ha Giang and U Dau Riu cattle were assigned to independent clusters while Nghe An, Thanh Hoa and Phu Yen cattle were grouped in a single cluster. We conclude that Vietnamese indigenous cattle have high levels of genetic diversity and distinct genetic structures. Based on these results, we recommend that for conservation homogenous populations (Nghe An, Thanh Hoa and Phu Yen) can be grouped to reduce costs and U Dau Riu, Lang Son and Ha Giang populations should be conserved separately to avoid loss of genetic diversity. 相似文献