全文获取类型
收费全文 | 267篇 |
免费 | 18篇 |
专业分类
林业 | 32篇 |
农学 | 11篇 |
基础科学 | 2篇 |
25篇 | |
综合类 | 24篇 |
农作物 | 49篇 |
水产渔业 | 10篇 |
畜牧兽医 | 119篇 |
园艺 | 7篇 |
植物保护 | 6篇 |
出版年
2023年 | 2篇 |
2022年 | 2篇 |
2021年 | 13篇 |
2020年 | 9篇 |
2019年 | 11篇 |
2018年 | 15篇 |
2017年 | 3篇 |
2016年 | 15篇 |
2015年 | 20篇 |
2014年 | 15篇 |
2013年 | 19篇 |
2012年 | 11篇 |
2011年 | 20篇 |
2010年 | 11篇 |
2009年 | 13篇 |
2008年 | 18篇 |
2007年 | 13篇 |
2006年 | 15篇 |
2005年 | 6篇 |
2004年 | 3篇 |
2003年 | 4篇 |
2002年 | 4篇 |
2001年 | 4篇 |
2000年 | 11篇 |
1999年 | 4篇 |
1998年 | 4篇 |
1997年 | 2篇 |
1995年 | 5篇 |
1994年 | 1篇 |
1993年 | 2篇 |
1991年 | 5篇 |
1990年 | 1篇 |
1984年 | 2篇 |
1979年 | 1篇 |
1972年 | 1篇 |
排序方式: 共有285条查询结果,搜索用时 46 毫秒
211.
WANG Shun-li Seong Sub Ku YE Xing-guo HE Cong-fen Suk Yoon Kwon Pil Son Choi 《农业科学学报》2015,14(3):469-482
Genetic transformation is an important technique for functional genomics study and genetic improvement of plants. Until now, Agrobacterium-mediated transformation methods using cotyledon as explants has been the major approach for cucumber, and its frequency has been up to 23%. For example, significantly enhancement of the transformation efficiency of this plant species was achieved from the cotyledon explants of the cultivar Poinsett 76 infected by Agrobacterium strains EHA105 with efficient positive selection system in lots of experiments. This review is to summarize some key factors influencing cucumber regeneration and genetic transformation, including target genes, selection systems and the ways of transgene introduction, and then to put forward some strategies for the increasing of cucumber transformation efficiency. In the future, it is high possible for cucumber to be potential bioreactor to produce vaccine and biomaterials for human beings. 相似文献
212.
Herein, we report the synthesis and dyeing property of cationic copper phthalocyanine (cationic CuPc). The synthesized cationic CuPc was characterized using UV-Vis spectra and it showed good solubility in aqueous solution over a wide pH range. The dyeing of cationic CuPc was successfully employed onto acrylic fiber. The dyeing of acrylic fiber using cationic CuPc was achieved using conventional method. The effects of five important variables such as liquor ratio, dye concentration, dyeing time, temperature and pH were examined on the color strength (K/S) of dyed acrylic fiber. The maximum color strength was obtained at lower liquor ratio (100:1), higher dye concentration (6 %), longer dyeing time (60 min), 120 °C and alkaline condition (pH 11). 相似文献
213.
214.
Agrotourism in Vietnam has been identified as one of the strategies used to achieve green growth and countryside modernisation, and it is often included as part of the national and local agenda. In this paper, we examine agrotourism in a village in the periphery of Hội An city (an international tourism hub in central Vietnam) to question tourism's interaction with ongoing development processes. More specifically, we aim to understand the impact of fast peri-urbanisation on agrotourism and the impacts of agrotourism on people's daily lives, specifically when it comes to physical changes in their living environment, tensions in their social life and their concerns about the future. Our analysis is supported with data generated from interviews with farmers, local officials, tourism workers and tourists. We find that agrotourism products lacked authenticity and farming was not of great interest for tourists, yet the state's investment in the village tended to favour spaces and infrastructure that could attract more tourists and generate profit, to the detriment of cultural infrastructure. Land speculation and an unequal distribution of income were the main tensions in the village along with farmers' concerns about their rural heritage, income diversification and environmental quality. As such, agrotourism in the village has been driven by rapid urbanisation and mass tourism, creating a competition between a consumption activity and a productive activity. Those are important parameters that future policymakers need to take into consideration in order to sustain the city's food production and tourism. 相似文献
215.
Vu Nam Son Nguyen Thanh Phuong Tran Ngoc Hai Amararatne Yakupitiyage 《Aquaculture International》2011,19(3):555-566
Production management of intensive prawn farming strongly differs between dry and wet season in terms of availability and
quality of prawn seeds and water quality. Secondary data implied that prawn seed batches from the market had a total pathogen
infection rate of 53%, predominantly caused by 37% white spot syndrome virus (WSSV), 19% monodon baculovirus (MBV) and 4%
yellow head virus (YHV). Pathogen-free seed batches averaged to 52% during the dry season compared to the wet season (42%).
Survey revealed average stocking density of 17 PL m−2 with a survival rate of 55%, a crop yield of 2,470 kg ha−1 crop−1 and a net income of 6,768 USD ha−1 crop−1. Average production cost amounted to 3.4 USD kg−1, and feed cost accounted for 58% of the production cost. Technical efficiency with respect to prawn yield and survival rate
was higher during the dry season than the wet season. The probability of yield loss was 15.6 times higher in the wet than
in the dry season. A positive net income can be generated for farms operating in the dry season using new ponds and performing
pathogen laboratory tests on prawn seeds before stocking. 相似文献
216.
Nguyen Minh Phuong Yumei Kang Katsutoshi Sakurai Kōzō Iwasaki Chu Ngoc Kien Nguyen Van Noi Le Thanh Son 《Water, air, and soil pollution》2010,207(1-4):319-332
Levels and chemical forms of heavy metals in forest, paddy, and upland field soils from the Red River Delta, Vietnam were examined. Forest soils contained high Cr and Cu levels that were higher in subsurface than in surface layers. Levels of Cu, Pb, and Zn that exceeded the limits allowed for Vietnamese agricultural soils were found in the surface layer of a paddy field near the wastewater channel of a copper casting village. High amounts of Zn accumulated in the surface soil of paddy fields close to a fertilizer factory and an industrial zone. In these cases, larger proportions of Cu, Pb, and Zn were found in the exchangeable and acid-soluble fractions compared to the low-metal soils. We conclude that no serious, large-scale heavy metal pollution exists in the Red River Delta. However, there are point pollutions caused by industrial activities and natural sources. 相似文献
217.
Long-term efficacy of aroma microcapsules on natural indigo-dyed cotton fabric was evaluated by objective and subjective tests. The fixation of aroma microcapsules was carried out by pad-dry-cure process on dyed cotton fabric. Mercerized cotton fabric was dyed with natural indigo obtained from Polygonum tintorium (via the modified Niram method) and subsequently padded with melamine-formaldehyde microcapsules containing aroma essential oil (natural source of a Chinese arborvitae 20-25 %). Softener was applied in the same (one-step) or sequential (two-step) padding bath. We confirmed that microcapsules were fixed on cotton fibers by SEM analysis. The addition of softener was not much effective for the fabric performances on softness or air permeability. All the colorfastness ratings were above 4/5 and the color difference was within the acceptable range of 1.62-2.08. The efficacy of fabric samples stored for 2 years was evaluated using the GC/MS-headspace technique and the samples stored for 0.5, 1.5, and 2.5 years were also evaluated in terms of aroma release by the human perception test. Bornyl acetate was confirmed as the main component of essential oil, which was continuously released by the microcapsule-treated fabric (D/MC) during storage for more than 2 years. In durability and human perception tests, the microcapsules on the cotton fabric were stable to laundering, rubbing, ironing, and light. 相似文献
218.
A-Young Shin Hyi-Seung Lee Yeon-Ju Lee Jong Seok Lee Arang Son Changhoon Choi Jihoon Lee 《Marine drugs》2020,18(12)
A total of eight new oxygenated 4-exo-methylene sterols, 1–8, together with one artifact 9 and six known sterols 11–16, were isolated from the marine sponge Theonella swinhoei collected from the Bohol province in Philippines. Structures of sterols 1–8 were determined from 1D and 2D NMR data. Among the sterols, 8α-hydroxytheonellasterol (4) spontaneously underwent an allylic 1,3-hydroxyl shift to produce 15α-hydroxytheonellasterol (9) as an artifact; this was rationalized by quantum mechanical calculations of the transition state. In addition, the 1,2-epoxy alcohol subunit of 8α-hydroxy-14,15-β-epoxytheonellasterol (5) was assigned using the Gauge-Independent Atomic Orbital (GIAO) NMR chemical shift calculations and subsequent DP4+ analysis. Finally, comparison of the 13C chemical shifts of isolated 7α-hydroxytheonellasterol (6) with the reported values revealed significant discrepancies at C-6, C-7, C-8, and C-14, leading to reassignment of the C-7 stereochemistry in the known structure. 相似文献
219.
Effect of dietary taurine levels on the conjugated bile acid composition and growth of juvenile Korean rockfish Sebastes schlegeli (Hilgendorf)
下载免费PDF全文
![点击此处可从《Aquaculture Research》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Shin‐Kwon Kim Kyoung‐Gil Kim Kyoung‐Duck Kim Kang‐Woong Kim Maeng‐Hyun Son Michael Rust Ronald Johnson 《Aquaculture Research》2015,46(11):2768-2775
This study was conducted to investigate the effects of different taurine levels on the conjugated bile acid composition and growth of juvenile rockfish. Five taurine level diets were made by the supplementation of taurine (0%, 0.5%, 1.0%, 1.5% and 2.0%) to a basal diet. Fish meal washed with 70% ethanol to exclude taurine was used for the sole protein source. Feeding experiments were accomplished at 15°C using juvenile fish (initial BW: 13.5 g). Fish were fed the experimental diets for 4 months. At the end of experiments, fish were weighed and stored at ?80°C for analysis of free amino acids and conjugated bile acids contents. The growth performance and feed efficiency of Korean rockfish were improved by taurine supplementation in the experimental diets. The taurine contents of the whole body increased with the increase in the taurine supplementation. The primary conjugated bile acids in gall bladder were taurocholic acid (83.5–165.6 mg mL?1) and taurochenodeoxycholic acid (6.3–20.0 mg mL?1). Total bile acids increased with increases in dietary taurine. Taurocholic acid content was more than 95% of the total conjugated bile acids. This indicates that taurine is the sole amino acid to make conjugated bile acid in Korean rockfish. Dietary taurine levels improved the conjugated bile acid composition in juvenile Korean rockfish. 相似文献
220.
H.C. Kwon S.H. Choi Y.U. Kim S.O. Son J.Y. Kwon 《Fish physiology and biochemistry》2003,28(1-4):351-352
Immature eels positively responded to estradiol-17β (E2) injection in terms of vitellogenin (Vg) synthesis but not to growth hormone (GH) or 17α-methyltestosterone (MT) injection. However, injection of MT or GH combined with E2 strongly increased Vg synthesis. In in vitro experiments, eel hepatocytes treated with E2, GH, or MT alone did not produce detectable amount of Vg, whereas the combination of E2 with GH or MT, or both greatly increased Vg synthesis in the hepatocytes. 相似文献