全文获取类型
收费全文 | 695篇 |
免费 | 17篇 |
国内免费 | 31篇 |
专业分类
林业 | 105篇 |
农学 | 56篇 |
基础科学 | 3篇 |
43篇 | |
综合类 | 331篇 |
农作物 | 71篇 |
水产渔业 | 2篇 |
畜牧兽医 | 58篇 |
园艺 | 30篇 |
植物保护 | 44篇 |
出版年
2024年 | 4篇 |
2023年 | 5篇 |
2022年 | 10篇 |
2021年 | 7篇 |
2020年 | 11篇 |
2019年 | 8篇 |
2018年 | 5篇 |
2017年 | 13篇 |
2016年 | 19篇 |
2015年 | 21篇 |
2014年 | 40篇 |
2013年 | 31篇 |
2012年 | 29篇 |
2011年 | 51篇 |
2010年 | 63篇 |
2009年 | 38篇 |
2008年 | 44篇 |
2007年 | 46篇 |
2006年 | 49篇 |
2005年 | 49篇 |
2004年 | 35篇 |
2003年 | 19篇 |
2002年 | 21篇 |
2001年 | 14篇 |
2000年 | 12篇 |
1999年 | 17篇 |
1998年 | 12篇 |
1997年 | 12篇 |
1996年 | 9篇 |
1995年 | 10篇 |
1994年 | 5篇 |
1993年 | 10篇 |
1992年 | 4篇 |
1991年 | 7篇 |
1990年 | 2篇 |
1989年 | 2篇 |
1988年 | 4篇 |
1987年 | 3篇 |
1986年 | 2篇 |
排序方式: 共有743条查询结果,搜索用时 976 毫秒
111.
112.
113.
114.
本文对转基因抗除草剂油菜品种、受体及当地常规品种田间昆虫多样性进行了调查。结果表明,不同品种间昆虫、害虫和天敌的物种数及个体数量之间存在极显著或显著差异;进一步分析表明,这种差异主要表现为转基因抗除草剂品种与受体品种之间的差异,而与当地的常规品种之间无显著差异。群落特征值群落丰富度、多样性指数在油菜的苗期及抽薹期,均以受体品种为最高;而在油菜的花期及结荚期,除花期的群落丰富度外,则以转基因抗除草剂的品种为最高。 相似文献
115.
116.
绵山天幕毛虫性信息素通讯系统扫描电镜观察 总被引:1,自引:0,他引:1
通过对绵山天幕毛虫性信息素释放系统——雌蛾性腺和性信息素接受系统——雄蛾触角进行扫描电镜观察,发现绵山天幕毛虫性信息素分泌腺位于腹尖末端8~9节之间,是一个可外翻的环状结构;性信息素感受器主要为毛形感器。绵山天幕毛虫性信息素通讯系统的研究为绵山天幕毛虫性信息素的快速提取、分析、合成提供了依据。 相似文献
117.
Hsiao-Wei Wen Hsiao-Ping Chung Ya-Ting Wang Po-Chow Hsieh I-Hsin Lin Fong-In Chou 《Postharvest Biology and Technology》2008,50(2-3):208-215
This study examines the protective effects of gamma irradiation against postharvest insect damage and microbial contamination and its effect on the nutritive value of adlay (Coix lacryma-jobi L.). Adlay was treated with doses of 0–20 kGy gamma irradiation and subsequently stored at ambient temperature. The number of insects, microbial quality and chemical properties of irradiated and non-irradiated adlay were evaluated immediately after treatment and after 6 months of storage. Before irradiation, total aerobic microbial counts ranged from 5.6 × 102 to 1.4 × 105 CFU g−1 and the mean total number of insects was 3.2 ± 2.1 per 100 g of polished kernel. Two kilograys was the lowest dose that provided 100% insect control. A radiation-resistant bacterium, Deinococcus radiodurans RC1, was found in 2 of 10 adlay samples. Four kilograys was a sufficient dose for Enterobacteriaceae inactivation, and 6 kGy was a sufficient dose for yeast and fungi inactivation. Twenty and 8 kGy sufficed for the inactivation of all mesophilic microbes in samples with and without D. radiodurans, separately. Moreover the moisture, ash, crude fiber, crude fat, crude protein and riboflavin content all remained constant. However, 8 kGy irradiation reduced vitamin B1 concentration by 24.2%, but did not measurably reduce the amount of amino acids, except methionine and cysteine. Fatty acid contents did not alter after 8 kGy irradiation, but changes were observed after the 6 months of storage. These changes caused by irradiation were no greater than those caused by the 6-month storage. Irradiation up to 8 kGy did not markedly increase the acid value, but did increase the peroxide value to 13% of the initial value right after irradiation. However, significant changes in acid value and peroxide value were noted after 6 months of storage both in non-irradiated and post-irradiated storage samples. Additionally, 8 kGy irradiation did not significantly change the adlay appearance. The improvement in the hygiene of this vital food source compensates for the small loss of some nutritional constituents. Hence 8 kGy of gamma irradiation can be used in cold decontamination of adlay to prolong shelf-life, to improve postharvest quality, and to reduce the risk of food-borne disease. 相似文献
118.
Inheritance and field performance of transgenic Korean Bt rice lines resistant to rice yellow stem borer 总被引:1,自引:0,他引:1
Songjin Kim Choljun Kim Wonnam Li Tokyong Kim Yongsu Li Mohsin Abbas Zaidi Illimar Altosaar 《Euphytica》2008,164(3):829-839
Transgenic Korean rice plants containing the cry1Ab gene were developed for resistance against yellow stem borer (Scirpophaga incertulas, YSB). More than 100 independent transgenic lines from three Korean varieties (P-I, P-II and P-III) were generated. The amount
of Cry1Ab in transgenic T0 plants was as high as 2.88% of total soluble proteins. These levels were sufficient to cause 100% mortality of YSB larvae.
The majority of T1 transgenic lines originated from the varieties P-I and P-II followed a Mendelian fashion of segregation. Deviation from the
expected segregation ratio was observed in a small number of the transgenic lines of P-I and P-II origins. However, this deviation
was primarily observed in the P-III originated lines. Segregation analysis of the T1 generation indicated that 1–3 copies of the cry1Ab gene were integrated into the genome of the majority of the transgenic lines originating from varieties P-I and P-II. Stunted
and semi-fertile mutants were observed in some transgenic lines. These aberrations were either independent or closely linked
to the introduced cry1Ab gene loci in different transgenic lines. Reduction in GUS expression levels and loss of toxicity against YSB larvae were
found in some transgenic lines. The transgenic T3 and T4 lines causing 100% mortality of third instar YSB larvae in the lab were completely protected in the field. Analysis of important
yield components on nine selected transgenic lines indicated that stem length, panicle length, grain number per panicle, and
seed setting rates were reduced in transgenic plants compared to those in non-transgenic parental rice lines. Number of panicles
per cluster, however, was significantly higher in transgenic plants. The numerical value of the average yield was in general
greater in the controls than in all the transgenic lines, indicating some ‘yield drag’. Since some selected lines were highly
resistant to the YSB with good yielding potential, they offer effective potential for use in insect resistance management
programs. 相似文献
119.
白三叶草坪昆虫群落调查及分析 总被引:2,自引:0,他引:2
通过对白三叶草坪的昆虫群落系统调查,运用群落的重要指标:样本昆虫数(S)、丰富度(N)、多样性指数(H')、均匀度(J)对该群落进行了分析,基本搞清了白三叶草坪昆虫群落的组分及其群落的演替情况。结果显示白三叶草坪昆虫群落由43种组成,分属13个目。其中,鞘翅目和半翅目是群落主体,蜗牛和豆象是害虫的优势种群,蜘蛛和瓢虫是天敌的优势种群。不同季节昆虫群落害虫和天敌的演替情况不同,尤其以夏末至秋季阶段最为突出。本研究为白三叶草坪的管理提供了科学理论依据。 相似文献
120.
杂交大豆昆虫传粉及制种技术研究进展 总被引:7,自引:0,他引:7
经过科学家的共同努力,吉林省农科院于2002年审定了世界上第1个大豆杂交种杂交豆1号,并于2006年审定了第2个大豆杂交种。从2000年开始,在封闭及开放条件下,利用苜蓿切叶蜂、蜜蜂、花蓟马等昆虫媒体为大豆传粉,进行不育系繁育及杂交种制种技术的探讨。已经实现在网室内利用蜜蜂及切叶蜂传粉,配制大豆杂交组合和生产小批量杂交种子,不育系结实率达到55.9%~100%;开放条件下,在干旱、有灌溉条件的地区,利用蜜蜂及苜蓿切叶蜂传粉,不育系结实率达到50%~80%,制种产量获得了较理想的结果。吉林省农科院在吉林省西部及内蒙古东部干旱地区,建立了制种基地,进行了较大面积的大豆不育系扩繁及杂交种制种试验,制种技术基本成熟。 相似文献