全文获取类型
收费全文 | 299篇 |
免费 | 17篇 |
专业分类
林业 | 30篇 |
农学 | 54篇 |
基础科学 | 2篇 |
38篇 | |
综合类 | 15篇 |
农作物 | 31篇 |
水产渔业 | 4篇 |
畜牧兽医 | 110篇 |
园艺 | 6篇 |
植物保护 | 26篇 |
出版年
2021年 | 6篇 |
2020年 | 4篇 |
2018年 | 6篇 |
2017年 | 13篇 |
2016年 | 9篇 |
2015年 | 6篇 |
2014年 | 2篇 |
2013年 | 16篇 |
2012年 | 14篇 |
2011年 | 15篇 |
2010年 | 10篇 |
2009年 | 7篇 |
2008年 | 5篇 |
2007年 | 25篇 |
2006年 | 8篇 |
2005年 | 11篇 |
2004年 | 7篇 |
2003年 | 8篇 |
2002年 | 10篇 |
2001年 | 3篇 |
2000年 | 3篇 |
1999年 | 5篇 |
1998年 | 4篇 |
1997年 | 7篇 |
1996年 | 4篇 |
1995年 | 3篇 |
1994年 | 4篇 |
1993年 | 2篇 |
1992年 | 2篇 |
1991年 | 5篇 |
1990年 | 3篇 |
1989年 | 3篇 |
1988年 | 7篇 |
1987年 | 4篇 |
1986年 | 6篇 |
1985年 | 2篇 |
1984年 | 5篇 |
1981年 | 3篇 |
1980年 | 5篇 |
1979年 | 5篇 |
1978年 | 4篇 |
1977年 | 3篇 |
1976年 | 2篇 |
1975年 | 5篇 |
1973年 | 2篇 |
1971年 | 5篇 |
1970年 | 4篇 |
1969年 | 2篇 |
1967年 | 5篇 |
1966年 | 2篇 |
排序方式: 共有316条查询结果,搜索用时 15 毫秒
311.
In order to update the available information on the main current and future constraints on wheat production and human capacity
development, a survey covering nineteen developing countries, including major wheat producers, was conducted prior to the
2006 International Symposium on Increasing Wheat Yield Potential in Ciudad Obregon, Mexico. The results emphasize the substantial
yield losses associated with a number of critical abiotic, biotic and socioeconomic constraints, and indicate their global
prevalence. The most important constraints on wheat production are heat (affecting up to 57% of the entire wheat area in surveyed
countries), competition with weeds, and diseases (both affecting up to 55% of wheat area). Of the socioeconomic constraints
listed and evaluated by respondents, access to mechanization and availability of credit were the most often highlighted. The
most-reported infrastructural constraints were insufficient resources for field station operations. When evaluating the importance
of research partnerships to achieve national wheat program goals, respondents from all 19 countries assigned the highest importance
to partnerships with international agricultural research centers. The most desired outputs from these include development
and exchange of germplasm and assistance in capacity building and knowledge sharing. These findings confirm the anticipated
constraints and needs over the next 10–20 years and affirm the importance of international agricultural research centers in
providing support to address them. 相似文献
312.
Joshi AK 《Science (New York, N.Y.)》1991,253(5025):1242-1249
Natural language processing (NLP) is the study of mathematical and computational modeling of various aspects of language and the development of a wide range of systems. These include spoken language systems that integrate speech and natural language; cooperative interfaces to databases and knowledge bases that model aspects of human-human interaction; multilingual interfaces; machine translation; and message-understanding systems, among others. Research in NLP is highly interdisciplinary, involving concepts in computer science, linguistics, logic, and psychology. NLP has a special role in computer science because many aspects of the field deal with linguistic features of computation and NLP seeks to model language computationally. 相似文献
313.
Recently, a strong research effort has been focused on applications of beat waves in plasma interactions. This research has important implications for various aspects of plasma physics and plasma technology. This article reviews the present status of the field and comments on plasma probing, heating of magnetically confined and laser plasmas, ionospheric plasma modification, beat-wave particle acceleration, beat-wave current drive in toroidal devices, beat wave-driven free-electron lasers, and phase conjugation with beat waves. 相似文献
314.
Keny Vanlalhriatpuia Vanlalnghaka Chhakchhuak Satralkar K Moses SB Iyyer MS Kasture AJ Shivagaje Barnabas J Rajneesh Dilip S Joshi 《Journal of circadian rhythms》2007,5(1):1-11
Background
We recently reported that the altitude of origin altered the photic and thermal sensitivity of the circadian pacemaker controlling eclosion and oviposition rhythms of high altitude Himalayan strains of Drosophila ananassae. The present study was aimed at investigating the effects of altitude of origin on the pacemaker controlling the adult locomotor activity rhythm of D. helvetica. 相似文献315.
Bhardwaj HL Hamama AA Rangappa M Joshi JM Sapra VT 《Plant foods for human nutrition (Dordrecht, Netherlands)》2003,58(3):197-205
Soyfood products like tofu are becoming popular among American consumers due to health benefits. In order to increase production to meet consumer demands, it is imperative that factors that effect quantity and quality of tofu be characterized. The present study was conducted to determine the effects of soybean genotypes and growing locations on contents of oil and fatty acids in tofu which was prepared from twelve soybean genotypes (BARC-8, BARC-9, Enrei, Hutcheson, MD86-5788, Nakasennari, S90-1056, Suzuyutaka, V71-370, V81-1603, Ware, and York) grown at three southern U.S. locations (Huntsville, Alabama; Princess Anne, Maryland; and Petersburg, Virginia) during 1995. The results showed that tofu quality was determined by the soybean genotype. The tofu made from seeds of high seed-protein and low seed-oil genotypes (BARC-8 and BARC-9) resulted in tofu with low contents of oil (15.8 and 11.3 g/100g, respectively) and total saturated fatty acids (2.59 and 160 g/100g, respectively). Tofu made from seeds of conventional grain type genotypes, such as Hutcheson, resulted in higher oil (24.0 g/100g) and total saturated fatty acids (3.80 g/100g) contents in tofu. Effects of growing environment on contents of oil were not significant but tofu made from seeds grown in Alabama had significantly higher content of total saturated fatty acids (3.50 g/100g) as compared to that made from seeds grown in Maryland (2.88 g/100g) or Virginia (2.96 g/100g). Tofu made from seeds of large and medium-seeded genotypes had higher contents of total monounsaturated fatty acids in tofu as compared to that made from small-seeded genotypes. Highly positive correlation existed between contents of oil, 18:1, 18:2, total saturated, and total unsaturated fatty acids in the seeds and their contents in the tofu (+0.80, +0.75, +0.79, +0.62, +0.68, respectively). These results indicated that tofu quality is governed by soybean genotype, seed size and growing location. 相似文献
316.