全文获取类型
收费全文 | 14389篇 |
免费 | 395篇 |
国内免费 | 20篇 |
专业分类
林业 | 1201篇 |
农学 | 380篇 |
基础科学 | 85篇 |
2225篇 | |
综合类 | 1552篇 |
农作物 | 712篇 |
水产渔业 | 1018篇 |
畜牧兽医 | 6245篇 |
园艺 | 387篇 |
植物保护 | 999篇 |
出版年
2023年 | 59篇 |
2022年 | 58篇 |
2021年 | 147篇 |
2020年 | 156篇 |
2019年 | 186篇 |
2018年 | 296篇 |
2017年 | 328篇 |
2016年 | 340篇 |
2015年 | 390篇 |
2014年 | 383篇 |
2013年 | 417篇 |
2012年 | 917篇 |
2011年 | 890篇 |
2010年 | 402篇 |
2009年 | 313篇 |
2008年 | 559篇 |
2007年 | 560篇 |
2006年 | 503篇 |
2005年 | 1195篇 |
2004年 | 1057篇 |
2003年 | 823篇 |
2002年 | 495篇 |
2001年 | 198篇 |
2000年 | 82篇 |
1999年 | 209篇 |
1992年 | 147篇 |
1991年 | 179篇 |
1990年 | 199篇 |
1989年 | 181篇 |
1988年 | 199篇 |
1987年 | 138篇 |
1986年 | 167篇 |
1985年 | 152篇 |
1984年 | 117篇 |
1983年 | 108篇 |
1979年 | 156篇 |
1978年 | 110篇 |
1977年 | 106篇 |
1976年 | 88篇 |
1975年 | 148篇 |
1974年 | 140篇 |
1973年 | 133篇 |
1972年 | 143篇 |
1971年 | 125篇 |
1970年 | 91篇 |
1969年 | 102篇 |
1968年 | 115篇 |
1967年 | 125篇 |
1966年 | 109篇 |
1965年 | 70篇 |
排序方式: 共有10000条查询结果,搜索用时 718 毫秒
111.
Incidence and risk factors for neurological signs after attenuation of single congenital portosystemic shunts in 253 dogs 下载免费PDF全文
112.
113.
Leonard Omadang Martin Chamai Emmanuel Othieno Andrew Okwi Francis Olaki Inangolet Francis Ejobi Peter Oba Michael Ocaido 《Tropical animal health and production》2018,50(1):11-17
A cross-sectional study was done from March 2013 to May 2014 to assess knowledge, attitudes, and practices towards cystic echinococcosis (CE) or hydatidosis among selected pastoral and agro-pastoral communities in Uganda. A structured questionnaire was administered to 381 respondents. Multivariate logistic regression analysis was done to find the relationship between knowledge about CE and factors such as age, sex, and level of education across all regions. The odds ratio and confidence interval were used to determine the difference in responses across regions. It was shown that age above 36 years was significantly (p < 0.001) associated with awareness about CE in livestock. Likewise, uneducated (p < 0.0001) and agro-pastoralists (p = 0.01) were significantly less knowledgeable than the educated and pastoralists across all regions. The overall knowledge towards CE in livestock was low 17.8% (95% CI = 14.0–21.6). Dog ownership was high and they never dewormed their freely roaming dogs. Dogs shared water with livestock. In conclusion, knowledge about CE in livestock was low across all regions. Therefore, public health education and formulation of policies towards its control by the relevant stakeholders should be done. Also, the true prevalence of CE in livestock needs to be done so that the magnitude and its public health significance are elucidated. 相似文献
114.
115.
Tomas Tubritt Luc Delaby Trevor Gilliland Michael O’Donovan 《Grass and Forage Science》2020,75(3):253-265
The objective of this study was to compare the grazing efficiency of 30 perennial ryegrass varieties, differing in ploidy and heading date. Plots were grazed by lactating dairy cows and managed under a rotational grazing system with 19 grazing events occurring over two years. Pre-grazing and post-grazing compressed sward heights were measured with a rising plate meter. A mixed model was used to predict the post-grazing sward height of each variety based on year, grazing event, block and pre-grazing sward height. Residual grazed height (RGH) was derived as the difference between the actual and predicted post-grazing sward height and was used as the measure of grazing efficiency. Negative RGH values indicated that the actual herbage removed was greater than that predicted and so indicated a superior grazing efficiency. Varieties differed in their level of grazing efficiency (p < .001), with RGH values ranging from −0.38 to +0.34 cm. Tetraploid varieties exhibited significantly greater grazing efficiency performance than diploids (p < .001), with average RGH values of −0.13 and +0.13 cm respectively. A significant difference in grazing efficiency was found among recommended perennial ryegrass varieties that are not being recorded by mechanically harvested simulated grazing protocols. A variety reappraisal that included grazing efficiency could identify varieties capable of improving on-farm livestock productivity from grass. 相似文献
116.
117.
Genze Nikita Bharti Richa Grieb Michael Schultheiss Sebastian J. Grimm Dominik G. 《Plant methods》2020,16(1):1-13
Photosynthesis is one of the most important biological reactions and forms the basis of crop productivity and yield on which a growing global population relies. However, to develop improved plant cultivars that are capable of increased productivity, methods that can accurately and quickly quantify photosynthetic efficiency in large numbers of genotypes under field conditions are needed. Chlorophyll fluorescence imaging is a rapid, non-destructive measurement that can provide insight into the efficiency of the light-dependent reactions of photosynthesis. To test and validate a field-deployed fluorescence imaging system on the TERRA-REF field scanalyzer, leaves of potted sorghum plants were treated with a photosystem II inhibitor, DCMU, to reduce photochemical efficiency (FV/FM). The ability of the fluorescence imaging system to detect changes in fluorescence was determined by comparing the image-derived values with a handheld fluorometer. This study demonstrated that the imaging system was able to accurately measure photochemical efficiency (FV/FM) and was highly correlated (r = 0.92) with the handheld fluorometer values. Additionally, the fluorescence imaging system was able to track the decrease in photochemical efficiency due to treatment of DCMU over a 7 day period. The system’s ability to capture the temporal dynamics of the plants’ response to this induced stress, which has comparable dynamics to abiotic and biotic stressors found in field environments, indicates the system is operating correctly. With the validation of the fluorescence imaging system, physiological and genetic studies can be undertaken that leverage the fluorescence imaging capabilities and throughput of the field scanalyzer. 相似文献
118.
Louise Mc Namara Kevin Gauthier Lael Walsh Gaël Thbaud Michael Gaffney Emmanuel Jacquot 《Pest management science》2020,76(7):2276-2285
Barley/cereal yellow dwarf viruses (YDVs) cause yellow dwarf disease (YDD), which is a continuous risk to cereals production worldwide. These viruses cause leaf yellowing and stunting, resulting in yield reductions of up to 80%. YDVs have been a consistent but low‐level problem in European cereal cultivation for the last three decades, mostly due to the availability of several effective insecticides (largely pyrethroids and more recently neonicotinoids) against aphid vectors. However, this has changed recently, with many insecticides being lost, culminating in a recent European Union (EU) regulation prohibiting outdoor use of the neonicotinoid‐insecticide compounds. This change is coupled with the growing challenge of insecticide‐resistant aphids, the lack of genetic resources against YDVs, and a knowledge deficit around the parameters responsible for the emergence and spread of YDD. This means that economic sustainability of cereal cultivation in several European countries including France and United Kingdom is now again threatened by this aphid‐vectored viral disease. In this review, we summarize the current knowledge on the YDV pathosystem, describe management options against YDD, analyse the impacts of the neonicotinoid ban in Europe, and consider future strategies to control YDV. © 2020 Society of Chemical Industry 相似文献
119.
Journal of Plant Diseases and Protection - A broad range of different Fusarium (F.) species is associated with Fusarium head blight (FHB) on barley and the corresponding negative effects in... 相似文献
120.