全文获取类型
收费全文 | 1219篇 |
免费 | 80篇 |
国内免费 | 1篇 |
专业分类
林业 | 75篇 |
农学 | 80篇 |
基础科学 | 6篇 |
194篇 | |
综合类 | 52篇 |
农作物 | 180篇 |
水产渔业 | 132篇 |
畜牧兽医 | 491篇 |
园艺 | 16篇 |
植物保护 | 74篇 |
出版年
2023年 | 9篇 |
2022年 | 24篇 |
2021年 | 38篇 |
2020年 | 32篇 |
2019年 | 32篇 |
2018年 | 41篇 |
2017年 | 42篇 |
2016年 | 44篇 |
2015年 | 44篇 |
2014年 | 65篇 |
2013年 | 72篇 |
2012年 | 94篇 |
2011年 | 94篇 |
2010年 | 63篇 |
2009年 | 46篇 |
2008年 | 72篇 |
2007年 | 73篇 |
2006年 | 75篇 |
2005年 | 50篇 |
2004年 | 54篇 |
2003年 | 48篇 |
2002年 | 39篇 |
2001年 | 34篇 |
2000年 | 20篇 |
1999年 | 9篇 |
1998年 | 2篇 |
1997年 | 7篇 |
1996年 | 2篇 |
1995年 | 2篇 |
1994年 | 2篇 |
1993年 | 3篇 |
1992年 | 3篇 |
1991年 | 5篇 |
1990年 | 3篇 |
1989年 | 2篇 |
1988年 | 6篇 |
1987年 | 5篇 |
1986年 | 4篇 |
1985年 | 2篇 |
1977年 | 2篇 |
1976年 | 3篇 |
1974年 | 2篇 |
1972年 | 3篇 |
1967年 | 4篇 |
1966年 | 9篇 |
1965年 | 4篇 |
1961年 | 2篇 |
1960年 | 2篇 |
1952年 | 1篇 |
1938年 | 1篇 |
排序方式: 共有1300条查询结果,搜索用时 15 毫秒
1.
I.-S. Park G. C. Choi D. S. Kim Y. K. Nam 《Journal of the World Aquaculture Society》2002,33(4):494-500
For the evaluation of hormonal control of spermiation in fish, a method to quanify the spermiation response of mature Rhynchocypris oxycephalus (Sauvage and Dabry) to hormonal therapy is described. Spermatocrit was determined after 7 min centrifugation at 18,000 ± g and sperm density was estimated by a standard hemocytomer method. Sperm density can be predicted from spermatocrit since their relationship is linear as described by the regression equation, Y = 3.68X - 27.18 ( R 2 = 0.82, N = 50). where Y is spermatocrit and × is sperm density. Milt production by mature R. oxycephalus was highest at 24 h after injection of 1,000 IU human chorionic gonadotropin (HCG) and 50 μg luteinizing hormone-releasing hormone analogue (LHRHa) per kg body weight. Increased milt production coincided with low spermatocrit and sperm density levels. These results demonstrate that spermiation in mature R. oxycephalus can be reliably evaluated by a spermatocrit method and that HCG and LHRHa are effective in stimulating of spermiation in this species. 相似文献
2.
K. Jung Y. Ha S.‐K. Ha D. U. Han D.‐W. Kim W. K. Moon C. Chae 《Zoonoses and public health》2004,51(2):72-76
The aim of these experiments was to investigate the potential antiviral effect of Saccharomyces cerevisiaeβ‐glucan on the pneumonia induced by swine influenza virus (SIV). Forty colostrum‐deprived 5‐day‐old piglets were randomly divided into four groups of 10. The 20 pigs in groups 1 and 2 were administered Saccharomyces cerevisiaeβ‐glucan orally (50 mg/day/pig; En‐Bio Technology Co., Ltd) for 3 days before SIV infection and those in groups 3 and 4 were given culture medium/diluent alone. Groups 1 and 3 were inoculated intranasally with 3 ml of tissue culture fluid containing 2 × 106 tissue culture infective doses 50% (TCID50)/ml of SIV and those in groups 2 and 4 were exposed in the same manner to uninfected cell culture supernatant. The microscopic lung lesions induced by SIV infection (group 1 pigs) were significantly more severe than those induced by infection in animals pre‐administered β‐glucan (group 3) (P < 0.05). Significantly more SIV nucleic acid was detected in the lungs of pigs experimentally infected with SIV only (group 1) at 5, 7 and 10 days post‐inoculation (dpi) compared with lungs from pigs pre‐administered β‐glucan and infected with SIV (group 3) (P < 0.05). The concentrations of interferon‐γ (IFN‐γ) and nitric oxide (NO) in bronchoalveolar lavage fluid from pigs pre‐administered β‐glucan and infected with SIV (group 3) were significantly higher than for any other group at 7 and 10 dpi for IFN‐γ, and at 5, 7 and 10 dpi for NO (P < 0.05). Saccharomyces cerevisiaeβ‐glucan reduced the pulmonary lesion score and viral replication rate in SIV‐infected pigs. These findings support the potential application of β‐glucan as prophylactic/treatment agent in influenza virus infection. 相似文献
3.
Khan MN Cho JY Lee MC Kang JY Park NG Fujii H Hong YK 《Journal of agricultural and food chemistry》2007,55(17):6984-6988
Two anti-inflammatory omega-3 polyunsaturated fatty acids (PUFAs) of stearidonic acid (SA) and eicosapentaenoic acid (EPA) and one pro-inflammatory omega-6 PUFA of arachidonic acid (AA) were isolated from the edible brown seaweed Undaria pinnatifida. SA was active against mouse ear inflammation induced by phorbol myristate acetate, with IC50 values of 160, 314, and 235 microg per ear for edema, erythema, and blood flow, respectively. EPA was also active against edema, erythema, and blood flow, with IC50 values of 230, 462, and 236 microg per ear, respectively. Although AA at low concentrations showed anti-inflammatory activities when measured 10 h later, AA doses of more than 243 microg per ear induced inflammatory symptoms 1 h later. Mature thalli generally had larger amounts of PUFAs than young thalli. The algal blade contained more omega-3 PUFAs than were found in other parts, while the holdfast contained extremely high amounts of AA. Late-season thalli showed increased amounts of PUFAs, especially AA. 相似文献
4.
Lee SC Kim JH Jeong SM Kim DR Ha JU Nam KC Ahn DU 《Journal of agricultural and food chemistry》2003,51(15):4400-4403
After far-infrared (FIR) radiation onto rice hull, a methanolic extract was prepared for the determination of antioxidant ability. After 30 min of FIR treatment, the radical scavenging activity and total phenol contents of rice hull extracts increased from 47.74 to 79.63% and from 0.12 to 0.19 mM, respectively, compared to control. Inhibition of lipid peroxidation in extracts was also increased from 41.07 to 47.96%. According to the GC-MS analysis, more phenolic compounds (p-coumaric acid, 3-vinyl-1-oxybenzene, p-hydroxybenzaldehyde, vanillin, p-hydroxybenzoic acid, and 4,7-dihydroxyvanillic acid) were detected in FIR-irradiated rice hull extract. These results indicated that FIR radiation onto rice hull could liberate and activate covalently bound phenolic compounds that have antioxidant activities. 相似文献
5.
Headspace solid phase microextraction (HS-SPME) was used to isolate the off-flavor volatile compounds, which are formed during the oxidation of porcine liver induced by iron. Poly(dimethylsiloxane)/divinylbenzene fiber was used in the HS-SPME. Changes in the volatile compounds of oxidized porcine liver and unsaturated fatty acids induced by iron were examined. Results showed that 1-octen-3-one (metallic), hexanol (weak metallic), 1-octen-3-ol (mushroomlike), (E)-2-nonenal (cardboardlike), and (E,E)-2,4-decadienal (fatty, oily) were the main contributors to the overall off-flavor of porcine liver. The results of the sensory evaluation revealed that oxidized arachidonic acid has a major impact on metallic and liverlike off-flavor and that when liverlike off-flavor is perceived, metallic is also included. Oxidized linolenic acid was the most important contributor to the objectionable fishy off-flavor. Oxidized porcine liver exhibited distinct metallic, liverlike, and weak fishy background notes. Liverlike flavor had a high correlation coefficient with odor characteristics such as metallic (0.839) and fishy (0.777). In this study, it was clearly observed that the stronger the metallic and fishy off-flavor the higher the perception of liverlike off-flavor. 相似文献
6.
Compressed wooden plates and dowels were used to connect members in post-and-beam structures as a substitute for a steel fastener.
In order to take advantage of the characteristic properties of compressed wood and to achieve optimum joint performance, two
compressed wooden plates were used in each joint to give multiple shear planes for each compressed wooden dowel. Consequently,
this type of joint showed very good properties in pull-out and momen-trotation performance, and its engineering design could
be further optimized. This joint is expected to be introduced to many kinds of structural systems, including long-span frame
structures made of domestic timber found in Japanese residential houses. 相似文献
7.
Mun Sup Yoon Jeongran Lee Chang Yung Kim Jung Hoon Kang Eun Gi Cho Hyung Jin Baek 《Euphytica》2009,165(1):69-77
Approximately 7,000 accessions of Korean soybean (Glycine max (L.) Merrill) landraces, largely composed of three collections, the Korea Atomic Energy Research Institute’s soybean (KAS),
the Korean Crop Experiment Station’s soybean (KLS) and the Korean Agricultural Development and Technology Center’s soybean
(KADTC) collections, have been conserved at the Rural Development Administration (RDA) genebank in Korea. The accessions within
collections were classified based on their traditional uses such as sauce soybean (SA), sprouted soybean (SP), soybean for
cooking with rice (SCR), and OTHERS. A total of 2,758 accessions of Korean soybean landraces were used to profile and to evaluate
genetic structure using six SSR loci. A total of 110 alleles were revealed by at the six SSR loci. The number of alleles per
SSR locus ranged from 9 to 39 in Satt187 and Satt_074, respectively. The number of alleles ranged from 87 in the KADTC collection
to 96 in the KLS collection, and from 63 in the SCR group to 95 in the SP group. Nei’s average genetic diversity ranged from
0.68 to 0.70 across three collections, and 0.64 to 0.69 across the usage groups. The average between-group differentiation
(G
st) was 0.9 among collections, and 4.1 among the usage groups. The similar average diversity among three collections implies
that the genetic background of the three collections was quite similar or that there were a large number of duplicate accessions
in three collections. The selection from the four groups classified based upon usage may be a useful way to select accessions
for developing a Korean soybean landrace core collection at the RDA genebank. DNA profile information of accessions will provide
indications of redundancies or omissions and aid in managing the soybean collection held at the RDA genebank. The information
on diversity analysis could help to enlarge the genetic diversity of materials in breeding programs and could be used to develop
a core collection. 相似文献
8.
Nazgol Emrani Mario Hasler Dilan S. R. Patiranage Maldonado-Taipe Nathaly Elodie Rey Christian Jung 《Plant Breeding》2020,139(6):1190-1200
Quinoa offers a promising alternative for staple food, considering its outstanding nutritional value and tolerance to abiotic stresses. To develop breeding programmes in quinoa, a reliable crossing method for increasing the genetic variation is required. In the following study, we aimed to develop segregating populations in quinoa. We tested the efficiency of three different crossing methods (hand emasculation, warm water emasculation and no emasculation). Moreover we developed a two-stage selection strategy based on morphological traits and molecular markers for the selection of hybrid plants. We reported hand emasculation to be the most efficient crossing method, followed by warm water emasculation and no emasculation. Our results demonstrated that crosses in quinoa can be successfully performed, despite its complicated flower structure and high self-pollination rate. Additionally, we developed 30 segregating populations from crosses between accessions of different origins with varying phylogenetic relationship, which offers a promising perspective for quinoa breeding programmes in the future. 相似文献
9.
褐稻虱在中抗水稻品种上的刺探频率低于抗级品种。虽然褐稻虱在中抗品种上能正常取食,但同化利用率较低。中抗品种受害后,无论是植株损害系数、光合作用强度降低程度或产量损失率均显著较感虫品种的少,说明了受害后较之感虫品种具有较强的补偿能力。另外,水稻品种受害后呼吸强度均较健株的明显降低。 相似文献
10.
In bone tissue regeneration, extracellular matrix (ECM) and bioceramics are important factors, because of their osteogenic potential and cell–matrix interactions. Surface modifications with hydrophilic material including proteins show significant potential in tissue engineering applications, because scaffolds are generally fabricated using synthetic polymers and bioceramics. In the present study, carbonated hydroxyapatite (CHA) and marine atelocollagen (MC) were extracted from the bones and skins, respectively, of Paralichthys olivaceus. The extracted CHA was characterized using Fourier transform infrared (FTIR) spectroscopy and X-ray diffraction (XRD) analysis, while MC was characterized using FTIR spectroscopy and sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). The scaffolds consisting of polycaprolactone (PCL), and different compositions of CHA (2.5%, 5%, and 10%) were fabricated using a three-axis plotting system and coated with 2% MC. Then, the MC3T3-E1 cells were seeded on the scaffolds to evaluate the osteogenic differentiation in vitro, and in vivo calvarial implantation of the scaffolds was performed to study bone tissue regeneration. The results of mineralization confirmed that the MC/PCL, 2.5% CHA/MC/PCL, 5% CHA/MC/PCL, and 10% CHA/MC/PCL scaffolds increased osteogenic differentiation by 302%, 858%, 970%, and 1044%, respectively, compared with pure PCL scaffolds. Consequently, these results suggest that CHA and MC obtained from byproducts of P. olivaceus are superior alternatives for land animal-derived substances. 相似文献