全文获取类型
收费全文 | 16511篇 |
免费 | 0篇 |
专业分类
林业 | 3634篇 |
农学 | 1295篇 |
基础科学 | 137篇 |
2775篇 | |
综合类 | 724篇 |
农作物 | 2105篇 |
水产渔业 | 1778篇 |
畜牧兽医 | 1073篇 |
园艺 | 1113篇 |
植物保护 | 1877篇 |
出版年
2023年 | 1篇 |
2022年 | 3篇 |
2021年 | 6篇 |
2020年 | 4篇 |
2019年 | 4篇 |
2018年 | 2744篇 |
2017年 | 2703篇 |
2016年 | 1179篇 |
2015年 | 66篇 |
2014年 | 24篇 |
2013年 | 14篇 |
2012年 | 797篇 |
2011年 | 2137篇 |
2010年 | 2107篇 |
2009年 | 1258篇 |
2008年 | 1320篇 |
2007年 | 1582篇 |
2006年 | 32篇 |
2005年 | 103篇 |
2004年 | 106篇 |
2003年 | 153篇 |
2002年 | 65篇 |
2001年 | 5篇 |
2000年 | 41篇 |
1999年 | 1篇 |
1998年 | 1篇 |
1995年 | 3篇 |
1994年 | 1篇 |
1993年 | 12篇 |
1992年 | 8篇 |
1991年 | 1篇 |
1990年 | 1篇 |
1989年 | 5篇 |
1988年 | 11篇 |
1987年 | 1篇 |
1978年 | 1篇 |
1977年 | 4篇 |
1972年 | 1篇 |
1969年 | 1篇 |
1968年 | 4篇 |
1967年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 23 毫秒
991.
Omar F. Ayman Yogesh Kumar Vipin Hallan Aijaz A. Zaidi 《Journal of General Plant Pathology》2010,76(5):351-354
In November 2008 in Himachal Pradesh and Chandigarh regions in India, toon trees and periwinkles were observed to have formed
short internodes, small leaves and witches’-broom symptoms, typical of phytoplasma infection. The symptomatic toon and periwinkle
samples were tested with universal PCR tests, and the 16S rRNA, rplB-rpsC, secA and secY genes were sequenced. The causal agents belonged to subgroup 16SrI-B of ‘Candidatus Phytoplasma asteris’, based on 16S rDNA, ribosomal protein gene, secA and secY phylogenetic analysis. 相似文献
992.
Tao Wang Dengyue Yuan Chaowei Zhou Fangjun Lin Rongbin Wei Hu Chen Hongwei Wu Zhiming Xin Ju Liu Yundi Gao Defang Chen Shiyong Yang Yan Wang Yundan Pu Zhiqiong Li 《Fish physiology and biochemistry》2016,42(3):883-893
Melanin-concentrating hormone (MCH) is a crucial neuropeptide involved in various biological functions in both mammals and fish. In this study, the full-length MCH cDNA was obtained from Schizothorax prenanti by rapid amplification of cDNA ends polymerase chain reaction. The full-length MCH cDNA contained 589 nucleotides including an open reading frame of 375 nucleotides encoding 256 amino acids. MCH mRNA was highly expressed in the brain by real-time quantitative PCR analysis. Within the brain, expression of MCH mRNA was preponderantly detected in the hypothalamus. In addition, the MCH mRNA expression in the S. prenanti hypothalamus of fed group was significantly decreased compared with the fasted group at 1 and 3 h post-feeding, respectively. Furthermore, the MCH gene expression presented significant increase in the hypothalamus of fasted group compared with the fed group during long-term fasting. After re-feeding, there was a dramatic decrease in MCH mRNA expression in the hypothalamus of S. prenanti. The results indicate that the expression of MCH is affected by feeding status. Taken together, our results suggest that MCH may be involved in food intake regulation in S. prenanti. 相似文献
993.
The effects of 6, 10 and 14 days of skip-a-day feed removal during the starter and grower periods on the growth performance of Ross 308 and Hubbard broiler chickens were studied in a 49-day production period. Ross 308 was superior to Hubbard in weight gain, market weight and feed utilization but consumed more feed, deposited more abdominal fat and had a higher mortality rate. Overall, feed removal improved feed efficiency, had insignificant effects on abdominal fatness and mortality rate and reduced feed intake, weight gain and market weight. On each restricted-feeding regime, the birds gained as much weight as their fully fed counterparts during the period of resumed full feeding but were unable to compensate fully for the weight loss and were lighter at the end of the trial. It is suggested that for profitable broiler production under tropical conditions, Ross 308 and skip-a-day feed removal for less than 6 days from 7 to 17 days of age be considered. 相似文献
994.
<Emphasis Type="Italic">Turnip yellow mosaic virus</Emphasis> isolated from Chinese cabbage in Japan
Namiko Kirino Koji Inoue Koji Tanina Yuya Yamazaki Satoshi T. Ohki 《Journal of General Plant Pathology》2008,74(4):331-334
A virus that caused a distinct yellow mosaic was isolated in Okayama, Japan from Chinese cabbage (Brassica rapa L., Pekinensis group). The virus, with spherical particles ca. 28 nm in diameter, was mechanically transmissible only to
cruciferous species. From the host range, characteristic morphology of virus particles, serology and sequence analysis of
coat protein gene, the causal virus was identified as Turnip yellow mosaic virus (TYMV). Seed transmission of TYMV at 0–2.2% in Chinese cabbage was confirmed. This report is the first of TYMV from Chinese
cabbage and in Japan.
The nucleotide sequence data reported are available in the DDBJ/EMBL/GenBank databases as accessions AB358971 and AB358972. 相似文献
995.
Luciana Pontes Silva Aline Cristina Sant’Anna Lívia Carolina Magalhães Silva Mateus José Rodrigues Paranhos da Costa 《Tropical animal health and production》2017,49(1):153-162
The aim of this study was to determine whether applying good practices of handling during the pre-weaning period have long-term effects on behavioral and physiological indicators, health status, and average daily gain (ADG) of crossbred Bos taurus × Bos indicus heifer calves. During the pre-weaning period, 98 crossbred of Holstein × Gir heifer calves were allotted into three treatments: (1) good practices of handling + brushing (GPB; n?=?25), (2) good practices of handling (GP; n?=?25), and (3) control (n?=?48). Every 2 months, four evaluation periods (EV1 to EV4) were conducted to record data. Behavioral indicators comprised time to drive (TD), flight speed (FS), flight distance (FD), and composite reactivity score (CRS). Physiological indicators of acute stress during handling comprised respiratory and heart rates. Health status comprised data regarding occurrence of most common diseases (i.e., pneumonia and anaplasmosis). Collected data were analyzed by using a linear mixed model for repeated measures, Tukey’s test, and chi-squared procedures. Treatment influenced (P?<?0.05) TD, FS, and FD but not CRS (P?=?0.78). From EV1 to EV3, the control calves had the lowest TD. The GPB group had lower FS than the control but did not differ from GP. The GPB group had lower FD means than the other two groups in EV2, EV3, and EV4. No differences (P?>?0.05) due to treatment were observed on heart and respiratory rates, ADG, or occurrence of pneumonia and anaplasmosis. It was concluded that adoption of good practices of handling during pre-weaning period may lead to long-term positive effects. 相似文献
996.
997.
Zhiyao Dong Dalu Li Xiaoxiao Hu Lijun Liang Guocan Wu Siyuan Zeng Erbao Liu Yue Wu Hui Wang Lal Bux Bhanbhro Xiaojing Dang Delin Hong 《Euphytica》2018,214(7):117
Flag leaf angle (FLA) in rice (Oryza sativa L.) is one of the important traits affecting F1 seed production by mechanization. To elucidate the genetic mechanism of FLA and mine favorable marker alleles for F1 seed production in rice, we performed a genome-wide association study using phenotypic data over 2 years and genotypic data of 262 pairs of simple sequence repeat (SSR) markers collected from 441 rice accessions. We detected seven SSR marker loci associated with FLA and four loci were novel. The four newly found loci were RM6266 on chromosome 3, RM348 on chromosome 4, RM258 on chromosome 10 and RM7303 on chromosome 11. We found a total of 27 favorable alleles, of which four, i.e., RM348-130 bp, RM7303-90 bp, RM258-180 bp, and RM4835-230 bp, had phenotypic effects larger than 10°. Nine combinations, which increased FLA by 45.7°–94.7° through pyramiding the favorable alleles contained in seven typical accessions, were predicted. 相似文献
998.
ABSTRACT: The relation between the density of fish and parameters such as body weight, condition factor and the hepatic triglyceride (TG) content of masu salmon Oncorhynchus masou juveniles after release into a natural stream were studied. Hatchery-reared juveniles of different sizes and numbers were released in May 1999, 2000 and 2001, and investigations were carried out from July to September each year. The density of fish was relatively high in 1999, when juveniles of the largest size and number were released, but then continued to decrease during the investigation. The hepatic TG content remained considerably low in 1999, and there was a significant negative correlation between the density of fish and the hepatic TG content of the juveniles caught over three years. The initial fish size and number at release as well as the nutritional condition of the juveniles may affect the density of fish after release. 相似文献
999.
Anthony Winson 《Agriculture and Human Values》2008,25(4):499-511
To understand the phenomenon of the rapidly increasing prevalence of overweight and obese children and youth, it is especially
important to examine the school food environment, the role of structural factors in shaping this environment, and the resulting
nutrition and health outcomes. The paper examines research on school food environments in the US and Canada. It notes evidence
of widespread availability of poor nutrition products in both environments and delineates reasons for the situation, and examines
initiatives presently being undertaken in a number of jurisdictions in both countries to encourage healthy eating in schools.
Empirical data are presented from a pilot study of high schools in the Canadian province of Ontario. The study documents the
extent of student purchasing of nutrient-poor foods and beverages, and the structural factors internal and external to the
school that appear responsible for the availability of such products in food environments in this critical institutional sphere.
The paper also examines positive local initiatives in high schools that seek to encourage healthy eating in schools.
Anthony Winson PhD is a professor in the department of sociology and anthropology at the University of Guelph. He has written on agriculture, food and rural development, and restructuring issues related to Canada and the Third World for more than 20 years. Among his books are The Intimate Commodity: Food and the Development of the Agro-Industrial Complex in Canada (Garamond 1993) and, more recently, Contingent Work, Disrupted Lives (University of Toronto 2002, with Belinda Leach) which examines economic restructuring, the changing world of work, and the factors underlying sustainability in small manufacturing-dependent rural communities in several regions of Ontario. This book won the John Porter Book Prize of the Canadian Sociology and Anthropology Association for 2003. Dr. Winson’s current work is focused on the analysis of factors shaping the contemporary Canadian food environment and their role in producing what has been termed the “epidemic of obesity.” Particular attention is being paid to supermarkets and schools as part of broader-ranging research on the political economic context of the food environment. 相似文献
Anthony WinsonEmail: |
Anthony Winson PhD is a professor in the department of sociology and anthropology at the University of Guelph. He has written on agriculture, food and rural development, and restructuring issues related to Canada and the Third World for more than 20 years. Among his books are The Intimate Commodity: Food and the Development of the Agro-Industrial Complex in Canada (Garamond 1993) and, more recently, Contingent Work, Disrupted Lives (University of Toronto 2002, with Belinda Leach) which examines economic restructuring, the changing world of work, and the factors underlying sustainability in small manufacturing-dependent rural communities in several regions of Ontario. This book won the John Porter Book Prize of the Canadian Sociology and Anthropology Association for 2003. Dr. Winson’s current work is focused on the analysis of factors shaping the contemporary Canadian food environment and their role in producing what has been termed the “epidemic of obesity.” Particular attention is being paid to supermarkets and schools as part of broader-ranging research on the political economic context of the food environment. 相似文献
1000.
Ann Finan 《Agriculture and Human Values》2011,28(1):81-96
Small-scale, artisanal livestock production is framed as “other” by conventional livestock producers, and rural communities. This alterity, although not without cost, allows women to be involved as active entrepreneurs and managers in artisanal livestock production and also allows farmers to pursue management strategies with the explicit purpose of enhancing animal welfare. The case study presented here, an artisanal goat dairy farm managed by three women, demonstrates that by embracing feminine care identities, these women carve a space for themselves within livestock production in which they can pursue their own economic and affective goals. Analysis of ethnographic data also demonstrates that farmers’ decision-making regarding animal production is based on both affective and instrumental concerns. If we are to understand and operationalize the affective component of farmer decision making based on the livestock–farmer relationship, we must begin to consider to what extent livestock themselves are social actors. 相似文献