全文获取类型
收费全文 | 1261篇 |
免费 | 65篇 |
国内免费 | 1篇 |
专业分类
林业 | 53篇 |
农学 | 53篇 |
基础科学 | 7篇 |
217篇 | |
综合类 | 72篇 |
农作物 | 182篇 |
水产渔业 | 112篇 |
畜牧兽医 | 538篇 |
园艺 | 19篇 |
植物保护 | 74篇 |
出版年
2023年 | 12篇 |
2022年 | 21篇 |
2021年 | 53篇 |
2020年 | 23篇 |
2019年 | 26篇 |
2018年 | 35篇 |
2017年 | 35篇 |
2016年 | 56篇 |
2015年 | 53篇 |
2014年 | 52篇 |
2013年 | 68篇 |
2012年 | 91篇 |
2011年 | 108篇 |
2010年 | 63篇 |
2009年 | 48篇 |
2008年 | 93篇 |
2007年 | 69篇 |
2006年 | 57篇 |
2005年 | 55篇 |
2004年 | 55篇 |
2003年 | 51篇 |
2002年 | 56篇 |
2001年 | 47篇 |
2000年 | 33篇 |
1999年 | 15篇 |
1998年 | 3篇 |
1997年 | 3篇 |
1996年 | 2篇 |
1995年 | 1篇 |
1994年 | 1篇 |
1993年 | 2篇 |
1991年 | 2篇 |
1990年 | 3篇 |
1989年 | 4篇 |
1988年 | 2篇 |
1987年 | 4篇 |
1986年 | 2篇 |
1984年 | 6篇 |
1983年 | 4篇 |
1982年 | 1篇 |
1979年 | 1篇 |
1975年 | 2篇 |
1974年 | 1篇 |
1973年 | 1篇 |
1972年 | 4篇 |
1971年 | 1篇 |
1970年 | 1篇 |
1933年 | 1篇 |
排序方式: 共有1327条查询结果,搜索用时 15 毫秒
171.
Ho Seop Yoon Chul Won Park Ho Young Soh Il Woong Park & Sang Duk Choi 《Aquaculture Research》2009,40(2):242-245
The present study was designed to determine the positive effects of artificial illumination on the juvenile black seabream, Acanthopagrus schlegeli , by comparing stomach contents and growth between juveniles exposed to light and those maintained in the absence of light. The major prey items for juvenile black seabream reared in illuminated cages were amphipods (IRI%=50.5), copepods (IRI%=44.7) and polychaetes (IRI%=3.0), whereas those for the juveniles maintained in unilluminated cages were copepods (IRI%=96.0), amphipods (IRI%=3.4) and polychaetes (IRI%=0.6). The specific growth rates (SGR) of the juveniles reared in illuminated cages (0.99%) were significantly higher than those of the juveniles maintained in unilluminated cages (0.78%). 相似文献
172.
Effect of cross-linking agent structure on the shape memory property of polyurethane block copolymer
Effect of cross-linking agent on the shape memory and mechanical property of polyurethane (PU) block copolymer is comprehensively
investigated. The selected chemical cross-linking agents are glycerol, 1,2,6-trihydroxyhexane, and 2,4,6-trihydroxybenzaldehyde
that are differentiated from each other in having remote hydroxyl group and aromatic ring. Significant increase in maximum
stress was observed for all of the cross-linked PUs, although the cross-linker structure was different. Structural change
of PU after cross-linking as evidenced by differential scanning calorimetry and infrared spectra was not detected, suggesting
that interaction between PU chains remained intact. Shape recovery went to as high as 95 % after cross-linking for all of
the cross-linking agents, and shape retention did not improve even if cross-linker was used. The remarkable increase in shape
recovery and maximum stress definitely originated from the employment of a cross-linking agent, and the effect of different
cross-linker structure on shape memory and mechanical property is discussed. 相似文献
173.
Dong Gyu Choi Ming He Hua Fang Xin Lan Wang Xiao Qin Li Xiang Jun Leng 《Aquaculture Nutrition》2020,26(1):37-46
The present study investigated the effect of fish meal (FM) replacement with fermented soybean meal (FSM) on growth and feed utilization of rainbow trout. Two FSM products, FSM1 (more fermentation with more small peptide and acid than FSM2) and FSM2 were used to replace 20%, 40% and 60% of FM in control diet (250 g/kg FM), respectively (FSM1‐20, FSM1‐40, FSM1‐60, FSM2‐20, FSM2‐40 and FSM2‐60). Then the seven diets were fed to rainbow trout (18.1 g) for 8 weeks. Weight gain (WG), feed conversion ratio (FCR) and digestibility of crude protein and dry matter showed no significant difference among the groups of FSM1‐20, FSM1‐40, FSM2‐20, FSM2‐40 and the control, but WG significantly decreased and FCR increased when 60% FM was replaced by both FSMs (p < .05). The replacement of 40%, 60% FM resulted in lower villus height than the control (p < .05), and intestinal protease activity was lower in FSM2‐40, FSM2‐60 and FSM1‐60 groups than the control group (p < .05). In addition, the activity of alkaline phosphatase and superoxide dismutase increased with increasing levels of FSM (p < .05). In conclusion, dietary fish meal could be replaced by 40% with both FSMs without adverse effects on growth and feed utilization of rainbow trout based on an eight weeks feeding trial. 相似文献
174.
Xu Gao Han Gil Choi Seo Kyoung Park Ju Hyoung Kim Ok Hwan Yu Ki Wan Nam 《Aquaculture Research》2019,50(3):856-861
Juvenile sporophytes and gametophytes of Ecklonia stolonifera were incubated in combinations of three pCO2 levels (360, 720 and 980 ppmv) and two temperatures (10 and 15°C for sporophytes; 15 and 20°C for gametophytes) to examine potential effects of climate change on photosynthesis and growth. Sporophytes had significantly higher maximum quantum yields (Fv/Fm) and maximum relative electron transport rates (rETRmax) at 720 ppmv than 360 and 980 ppmv. Also, these parameters were significantly lower at higher temperature of 15°C than at 10°C. Growth of female gametophytes was maximal at 360 ppmv rather than enriched pCO2 levels. Female gametophytes had significantly lower growth at higher temperature of 20°C than at 15°C. These results indicate effects of elevated pCO2 varied between generations: stimulating sporophytic photosynthesis and inhibiting gametophytic growth. Ocean acidification and warming would constitute a grave threat to seedling cultivation of E. stolonifera caused by growth inhibition of gametophytes at high pCO2 levels and temperatures. 相似文献
175.
Xu Gao Jung Rok Lee Seo Kyoung Park Chul Won Kim Ju Hee Kim Han Gil Choi 《Aquaculture Research》2019,50(7):1985-1992
The red alga Chondria crassicaulis has a wide‐ranging bioactive chemical composition and is used as a local foodstuff, representing a potentially new cultivar in Korea. The cultivation techniques were developed by examining the monthly changes in frond weight in a field population of C. crassicaulis from November 2016 to October 2017. For seedling production, temperature and irradiance effects on the attachment and growth of vegetative propagules of C. crassicaulis were evaluated. In addition, effects of day length and salinity on the propagule growth were examined. C. crassicaulis is a year‐round species with a maximum frond wet weight of 817 mg observed in July 2017, as seawater temperature increases to 20°C. The attachment of vegetative propagules was significantly affected by temperature and irradiance, with maximal values detected at 20–25°C and 60 µmol photons m?2 s?1. The relative growth rates of vegetative propagules of C. crassicaulis were the highest at 20–25°C, 60 µmol photons m?2 s?1, and a salinity of 25 psu. In conclusion, due to its tremendous tolerance under variable environmental conditions, the vegetative propagules of C. crassicaulis can be used as seedlings for mass cultivation. 相似文献
176.
In Taek Hwang Kyung Sik Hong Jung Sup Choi Jin-Seog Kim Ju Hyun Yu Young Kwan Ko Jae Wook Ryu Hae Sung Chang Dae-Whang Kim Kwang Yun Cho 《Pest management science》1999,55(5):578-580
The new benzenesulfonylurea K-11451, an α-hydroxy-β-fluoropropyl- compound, applied at 3–9 g ha −1, controlled annual and perennial weeds grown in submerged paddy soil under greenhouse conditions. It effectively controlled barnyardgrass at growth stages varying from pre-emergence to the five-leaf stage. The compound inhibited acetolactate synthase, I50 values for the enzyme isolated from barnyardgrass and rice being 56 and 67 nM , respectively. K-11451 inhibited the growth of rice when it was transplanted at a shallow depth (0–1 cm) and water leaching from the paddy soil was high (3–5 cm per day). With a water depth of 3 cm, the compound appeared to move readily down into the paddy soil and had the relatively short half-life of 15.2 days under submerged paddy conditions. A mixture of K-11451 + mefenecet + daimuron (9 + 250 + 250 g ha−1) controlled almost all weeds in the paddy field without injury to rice, so that the combination could be used as a ‘one-shot’ herbicide in rice culture. 相似文献
177.
Sukyeung Lee Yu-Mi Choi Myung-Chul Lee Do Yoon Hyun Sejong Oh Yeonju Jung 《Genetic Resources and Crop Evolution》2018,65(6):1591-1602
Glutenin largely determines wheat bread baking quality. As high-molecular-weight glutenin subunit (HMW-GS), related to Glu-1 loci, determines wheat flour elasticity, it correlates strongly with bread-making quality. This study was aimed at clarifying genetic variations in bread-making characteristics between East and West Asian wheat landrace germplasms, by investigating HMW-GS allelic composition of 1068 wheat accessions. Herein, the accession number having reported HMW-GS pattern in previous studies was 855. However, the accession number with newly detected HMW-GS patterns was 114. These new HMW-GS patterns were classified into 4 types based on similarity. Eight Korean accessions with these four types were identified. Concerning landrace germplasm nature, 99 accessions showed heterogeneous patterns caused by seed mixture. The Glu-1 loci allelic variation analysis, revealed that the percentages of Glu-A1c (73.6%), Glu-B1b (60.2%), and Glu-D1a (68.5%) were highest at Glu-A1, Glu-B1, and Glu-D1 loci, respectively. The incidence of preferable alleles for bread baking was high in Chinese accessions. In bread-making quality evaluation using Glu-1 score, 24 among 35 accessions with full score were from China. The polymorphic information content index of each origin based on HMW glutenin subunit combination showed that West Asian and neighboring-regional landraces, excluding Afghanistan ones, were more diverse than East Asian landraces excluding Chinese ones. Cluster analysis based on Glu-1 allelic combination showed that many Korean, Japanese, and Afghan accessions were in the same group. However, many Chinese and other West Asian accessions were in the other group despite geographical distance. 相似文献
178.
179.
Myeong Jun Jo Howon Choi Ga Hee Kim Woong-Ryeol Yu Miseon Park Yeontae Kim Jong Kyoo Park Ji Ho Youk 《Fibers and Polymers》2018,19(9):1799-1805
In order to develop epoxy shape memory polymers (ESMPs) with high switching temperature and excellent toughness for deployable space structures, the crosslink density and chain flexibility of candidate ESMP samples were tunned by adding two flexible poly(oxypropylene) diamines, Jeffamine D-230 (D230) and Jeffamine D-400 (D400), as a secondary curing agent. The desired switching temperature of ESMPs for deployable space structures was set within the range of 120-135°C. By adding D230 and D400, the switching temperature of the ESMPs could be adjusted to within this range by increasing their crosslink density, and their impact strength could be significantly increased due to the stress relaxation properties of the diamines’ flexible molecular chains. The modulus and tensile strength of the ESMPs increased, but elongation at break decreased, in proportion to the diamine content. The ESMPs with a suitable switching temperature for deployable space structures had a high elongation at break greater than 22 % and good shape recovery and shape fixity ratios. The larger the value of shape recovery ratio, the faster the shape recovery speed. 相似文献
180.
Comparative evaluation of MCP gene in worldwide strains of Megalocytivirus (Iridoviridae family) for early diagnostic marker
下载免费PDF全文
![点击此处可从《Journal of fish diseases》网站下载免费的PDF全文](/ch/ext_images/free.gif)
A Mishra G‐H Nam J‐A Gim H‐E Lee A Jo D Yoon S Oh S Kim A Kim D‐H Kim Y C Kim H D Jeong H‐J Cha Y H Choi H‐S Kim 《Journal of fish diseases》2018,41(1):105-116
Members of the Iridoviridae family have been considered as aetiological agents of iridovirus diseases, causing fish mortalities and economic losses all over the world. Virus identification based on candidate gene sequencing is faster, more accurate and more reliable than other traditional phenotype methodologies. Iridoviridae viruses are covered by a protein shell (capsid) encoded by the important candidate gene, major capsid protein (MCP). In this study, we investigated the potential of the MCP gene for use in the diagnosis and identification of infections caused Megalocytivirus of the Iridoviridae family. We selected data of 66 Iridoviridae family isolates (53 strains of Megalocytivirus, eight strains of iridoviruses and five strains of Ranavirus) infecting various species of fish distributed all over the world. A total of 53 strains of Megalocytivirus were used for designing the complete primer sets for identifying the most hypervariable region of the MCP gene. Further, our in silico analysis of 102 sequences of related and unrelated viruses reconfirms that primer sets could identify strains more specifically and offers a useful and fast alternative for routine clinical laboratory testing. Our findings suggest that phenotype observation along with diagnosis using universal primer sets can help detect infection or carriers at an early stage. 相似文献