全文获取类型
收费全文 | 827篇 |
免费 | 15篇 |
专业分类
林业 | 50篇 |
农学 | 33篇 |
基础科学 | 2篇 |
107篇 | |
综合类 | 41篇 |
农作物 | 27篇 |
水产渔业 | 81篇 |
畜牧兽医 | 449篇 |
园艺 | 8篇 |
植物保护 | 44篇 |
出版年
2023年 | 5篇 |
2022年 | 12篇 |
2021年 | 19篇 |
2020年 | 15篇 |
2019年 | 11篇 |
2018年 | 23篇 |
2017年 | 11篇 |
2016年 | 14篇 |
2015年 | 15篇 |
2014年 | 22篇 |
2013年 | 70篇 |
2012年 | 36篇 |
2011年 | 30篇 |
2010年 | 16篇 |
2009年 | 22篇 |
2008年 | 46篇 |
2007年 | 49篇 |
2006年 | 41篇 |
2005年 | 39篇 |
2004年 | 33篇 |
2003年 | 38篇 |
2002年 | 30篇 |
2001年 | 32篇 |
2000年 | 26篇 |
1999年 | 21篇 |
1998年 | 10篇 |
1997年 | 6篇 |
1996年 | 4篇 |
1994年 | 6篇 |
1992年 | 10篇 |
1991年 | 7篇 |
1990年 | 8篇 |
1989年 | 9篇 |
1988年 | 9篇 |
1987年 | 12篇 |
1986年 | 8篇 |
1985年 | 11篇 |
1984年 | 9篇 |
1983年 | 5篇 |
1982年 | 2篇 |
1980年 | 2篇 |
1979年 | 4篇 |
1977年 | 5篇 |
1976年 | 3篇 |
1973年 | 6篇 |
1972年 | 8篇 |
1971年 | 2篇 |
1970年 | 3篇 |
1965年 | 6篇 |
1964年 | 3篇 |
排序方式: 共有842条查询结果,搜索用时 15 毫秒
141.
Viscoelasticity describes the ability of a material to possess both elasticity and viscosity. Viscoelastic materials, such as rubbers, possess a limited operational temperature range (for example, for silicone rubber it is -55° to 300°C), above which the material breaks down and below which the material undergoes a glass transition and hardens. We created a viscoelastic material composed from a random network of long interconnected carbon nanotubes that exhibited an operational temperature range from -196° to 1000°C. The storage and loss moduli, frequency stability, reversible deformation level, and fatigue resistance were invariant from -140° to 600°C. We interpret that the thermal stability stems from energy dissipation through the zipping and unzipping of carbon nanotubes at contacts. 相似文献
142.
Miori Kishimoto Sa-Hun Pae Naoyoshi Muroya Hirokazu Watarai Hiroshi Anzai Ki-Ja Lee Junichiro Shimizu Motoki Sasaki Kazutaka Yamada 《Journal of veterinary science (Suw?n-si, Korea)》2010,11(1):89-91
Caudolateral curvilinear osteophyte (CCO), an osteophyte at the site of joint capsule attachment on the caudal aspect of the femoral neck, has been advocated as a radiographic criterion for coxofemoral subluxation. The correlation between the presence of CCO on radiographs (radiographic-CCO), the size of the CCO (CCO index) on three-dimensional computed tomographic (CT) images, and hip evaluation using transverse CT images was assessed in 22 Border Collies. CCOs were detected on the radiographs and CT images of 32% and 100% femurs, respectively. The CCO index correlated significantly with radiographic-CCO, but a large CCO index did not necessarily imply that the CCO was visible on radiographs. Hence, radiographic-CCO findings should be used cautiously in hip evaluation of Border Collies. 相似文献
143.
Iimure T Kimura T Araki S Kihara M Sato M Yamada S Shigyou T Sato K 《Journal of agricultural and food chemistry》2012,60(6):1548-1554
Beer foam stability is an important characteristic. It has been suggested that isoforms of protein Z, that is, protein Z4 and protein Z7, contribute to beer foam stability. We investigated the relationship between beer foam stability and protein Z4 and protein Z7 using their deficient mutants. As a protein Z4-deficient mutant, cv. Pirkka was used. Protein Z7 deficiency was screened in 1564 barley accessions in the world collection of Okayama University, Japan. The barley samples from normal, protein Z4-deficient, protein Z7-deficient, and double-deficient were genotyped in F(2) populations and then pooled based on the DNA marker genotypes of protein Z4 and protein Z7. For a brewing trial, F(5) pooled subpopulations were used. After malting and brewing, the foam stability was determined, and the results showed that the levels of foam stability in the four samples were comparable. Two-dimensional gel electrophoresis was used to investigate the proteome in these beer samples. The results showed that low molecular weight proteins, including lipid transfer protein (LTP2), in the deficient mutants were higher than those in the normal sample. Our results suggest that the contribution of protein Z4 and protein Z7 to beer foam stability was not greater than that of other beer proteins. 相似文献
144.
Green- or brown-striped trematode sporocyst broodsacs typical of Leucochloridium infecting the ocular tentacles of a land snail, Succinea lauta, were collected in Abashiri, Hokkaido in northern Japan (N43 degrees 59', E144 degrees 14') in June of 2000 and 2001. The metacercariae isolated from the sporocyst broodsac were morphologically identified as Leucochloridium spp. (Leucoclhoridiidae Poche). This report is the first to describe evidential specimens of the sporocyst broodsac of the genus Leucochloridium Carus, 1835, infecting the intermediate host in Japan, suggesting that Leucochloridium spp. completes their life cycle in Hokkaido, Japan. 相似文献
145.
Nomura H Ogiso M Yamashita M Takaku H Kimura A Chikasou M Nakamura Y Fujii S Watai M Yamada H 《Journal of agricultural and food chemistry》2011,59(9):5150-5158
Uptake and elimination of aflatoxins (AFs) by rainbow trout ( Oncorhynchus mykiss ) during a long-term (21 days) dietary exposure were studied to assess contamination by AFs in aquaculture fish fed AF-containing feed. The uptake factor (UF) of aflatoxin B(1) (AFB(1)) in muscle ranged from 0.40 × 10(-3) to 1.30 × 10(-3). AFB(1) concentrations in liver were 165-342 times higher than in muscle. AFs from feed were more highly accumulated in liver than in muscle. Aflatoxicol (AFL) and aflatoxin M(1) (AFM(1)) were detected in muscle and liver and also in the rearing water. AFL concentrations were higher than AFM(1) by 2 orders of magnitude in muscle, and AFL was a major metabolite of AFB(1). The elimination rate constants (α) of AFB(1) and AFL in muscle (1.83 and 2.02 day(-1), respectively) and liver (1.38 and 2.41 day(-1), respectively) were very large. The elimination half-life (t(1/2)) of AFB(1) was 0.38 days (9.12 h) in muscle and 0.50 days (12.00 h) in liver. The elimination half-life of AFL in muscle and liver was 0.34 day (8.16 h) and 0.29 day (6.96 h), respectively. These data show that AFs are eliminated rapidly and are not biomagnified in fish. Thus, AFB(1) concentration in muscle of fish fed AFB(1)-containing feed (ca. 500 μg/kg) decreased to below the detection limit (20 ng/kg) of the most sensitive analytical method at 1.54 days (36.96 h) after the change to uncontaminated feed. 相似文献
146.
Viviane Maria Codognoto Paulo Henrique Yamada Rúbia Alves Schmith Felipe Rydygier de Ruediger Camila de Paula Freitas-Dell’Aqua Fabiana Ferreira de Souza Suzane Brochine Lucas Monteiro do Carmo Andressa Filaz Vieira Eunice Oba 《Reproduction in domestic animals》2020,55(1):81-92
The objective of this study was to evaluate seminal plasma proteins from cattle and buffalo (Bubalus bubalis), to identify differences between related species. Sixteen buffaloes and 16 cattle between 30 and 60 months of age were used. Semen collection was performed by electroejaculation, followed by macroscopic and microscopic subjective analyses. After analysis, the samples were centrifuged at 800 g for 10 min, and the supernatant (seminal plasma) was recentrifuged at 10,000 g for 30 min at 4°C. The total protein concentration was determined by the Bradford method, and the proteins were digested in solution for mass spectrometry (nLC-MS/MS). Multivariate statistical analysis was used to evaluate the proteomics results by non-hierarchical clustering the considering exponentially modified protein abundance index (emPAI). Principal component analysis (PCA) and partial least squares discriminant analysis (PLS-DA) were used for clustering. Proteomics identified 78 proteins, and multivariate analysis showed 4 that were over-expressed in buffaloes (cystatin C, prosaposin, peptide YY and keratin type II cytoskeletal 5) and 9 in cattle (spermadhesin-1, seminal plasma protein PDC-109, ribonuclease 4, metalloproteinase inhibitor 2, acrosin inhibitor 1, seminal ribonuclease, C-type natriuretic peptide, angiogenin-1 and osteopontin). Among the proteins identified in seminal plasma, the C-type natriuretic peptide and metalloproteinase inhibitors were described for the first time in buffaloes. Some protease inhibitors were found over-expressed in buffaloes, and important proteins in seminal plasma of cattle were not identified or were found at lower expression levels in buffaloes, which can contribute to reproductive performance in this species. 相似文献
147.
Satoko Watanabe Kimihito Nakamura Chan Seok Ryu Michihisa Iida Shigeto Kawashima 《Soil Science and Plant Nutrition》2013,59(2):224-237
Treatment of animal and food wastes using a methane fermentation technique is drawing considerable public attention as a suitable option for the utilization of biomass resources. The application of a fermentation byproduct (methane fermentation digested liquid) as an agricultural fertilizer has been investigated. Determining the appropriate timing required for applying digested liquid on a rice (Oryza sativa L.) paddy plot is important. The concentrations of soil nitrogen (N) components and rice yield should be considered because digested liquid contains both inorganic and organic N. This study compares the N transformation and the rice yield and growth at different application times over a period of 3 y. The effects of the timing of basal application on soil N were different and the timing that maximized the rice yield was different in each year. Days before ponding (DBP) affected soil N before mid-summer drainage, and rice growth rates at the panicle formation stage and the ear emergence stage. The effects of DBP disappeared before harvest. The results indicated that sufficient potentially mineralizable N existed regardless of DBP, and the effect of DBP lessened after the mid-summer drainage, which coincides with the period when N uptake is most active. 相似文献
148.
Results, here published, are from the determination of the colour, by the use of spectrophotometer (Shimazu, QR-50) with the soils from pedogenic horizons of principal soil types In Japan. 相似文献
149.
In the last report1) the purity of radioactive potassium. which had been produced by 41K (d, p) 42K nuclear reaction and separated from, radioactive anions by the use of ion exchange resin, was tested by means of its decay curve. By this test, it is difficult to distinguish 42K from 24Na contamination, because the half life of radioactive sodium (24Na) is 15.06 hours2) and it is very similar to that of radioactive potassium (42K) which is 12.4 hours. When the nuclear reaction 23Na (d, p) 24Na occurs, the cross section of this reaction for deuterons is about 100 times that of potassium nuclear reaction. In this case the purity of radioactive potassium (42K) could be confirmed by its Gamma-ray spectrum. According to the result, radioactive potassium of high purity was obtained. Potassium phosphate which was double-labeled by this radioactive potassium and imported radioactive phosphorus (32P) was applied to leaves or roots of bean plants. 相似文献
150.
Active surface agents are often added to spray solutions to facilitate the uniform wetting and coveringg of the leaf surfaces1),2). Some have reported that the addition of active surface agents increased the absorption of nutrients, but others have reported different results. 相似文献