全文获取类型
收费全文 | 17036篇 |
免费 | 898篇 |
国内免费 | 17篇 |
专业分类
林业 | 828篇 |
农学 | 558篇 |
基础科学 | 122篇 |
2505篇 | |
综合类 | 2664篇 |
农作物 | 911篇 |
水产渔业 | 950篇 |
畜牧兽医 | 8308篇 |
园艺 | 197篇 |
植物保护 | 908篇 |
出版年
2020年 | 161篇 |
2019年 | 182篇 |
2018年 | 310篇 |
2017年 | 365篇 |
2016年 | 261篇 |
2015年 | 198篇 |
2014年 | 316篇 |
2013年 | 665篇 |
2012年 | 496篇 |
2011年 | 620篇 |
2010年 | 428篇 |
2009年 | 410篇 |
2008年 | 628篇 |
2007年 | 552篇 |
2006年 | 513篇 |
2005年 | 453篇 |
2004年 | 420篇 |
2003年 | 429篇 |
2002年 | 369篇 |
2001年 | 486篇 |
2000年 | 475篇 |
1999年 | 373篇 |
1998年 | 180篇 |
1997年 | 201篇 |
1996年 | 156篇 |
1995年 | 192篇 |
1993年 | 164篇 |
1992年 | 280篇 |
1991年 | 313篇 |
1990年 | 307篇 |
1989年 | 312篇 |
1988年 | 289篇 |
1987年 | 246篇 |
1986年 | 295篇 |
1985年 | 253篇 |
1984年 | 209篇 |
1983年 | 207篇 |
1979年 | 250篇 |
1978年 | 165篇 |
1977年 | 155篇 |
1975年 | 171篇 |
1974年 | 234篇 |
1973年 | 215篇 |
1972年 | 251篇 |
1971年 | 230篇 |
1970年 | 203篇 |
1969年 | 192篇 |
1968年 | 158篇 |
1967年 | 160篇 |
1966年 | 161篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
131.
Fracture of the medial intercondylar eminence of the tibia in horses treated by arthroscopic fragment removal (21 horses) 下载免费PDF全文
132.
Neto JO Azevedo SS Gennari SM Funada MR Pena HF Araújo AR Batista CS Silva ML Gomes AA Piatti RM Alves CJ 《Veterinary parasitology》2008,156(3-4):329-332
The prevalence and risk factors for anti-Toxoplasma gondii antibodies were investigated in goats of the Seridó Oriental microregion, Rio Grande do Norte state, Northeast region of Brazil. Three hundred and sixty-six blood samples from goats collected by jugular venopuncture were used. For the serologic diagnosis of Toxoplasma gondii infection, the indirect fluorescent-antibody test (IFAT) with cut-off value 1:64 was carried out. The prevalence of anti-T. gondii antibodies was 30.6% [95% CI=25.9-35.6%] with titers ranging from 1:64 to 1:16,384. The multivariate logistic regression analysis showed that the risk factors associated to anti-T. gondii antibodies were presence of cats in the herd, extensive/semi-intensive management systems and lack of mineral supplementation. 相似文献
133.
134.
135.
I. B. Griffiths D. G. Parra O. G. Vizcaino M. I. Gallego 《Tropical animal health and production》1986,18(3):155-157
Summary When 1, 711 bovine faecal samples from 113 farms in eight dairy areas of Colombia were examined for the presence of helminth
eggsFasciola hepatica eggs were found in the faeces from 60% of the farms and samples from animals kept above 2,000 m. Strongyle eggs were found
in faeces from 82% of the farms and in 18% of the samples.
Resumen Se examinaron 1.711 muestras fecales provenientes de 113 fincas, localizadas en ocho zonas lecheras de Colombia. Se encontraron huevos deFasciola hapatica, en el 60% de fincas y muestras fecales de animales sobre los 2,000 m.s.n.m. Se encontraron tambien huevos de estrogilideos en heces del 82% de fincas y en el 18% de las muestras examinadas.
Résumé La recherche d’oeufs d’helminthes sur 1711 échantillons de fécès provenant de 113 fermes de 8 districts laitiers de Colombie a permis de noter la présence d’oeufs deFasciola hepatica dans 60 p. 100 des fermes et échantillons originaires d’animaux vivant à plus de 2,000 m. Des oeufs de strongles ont été notés dans les fécès provenant de 82 p. 100 des fermes et 18 p. 100 des échantillons.相似文献
136.
137.
Hakan Salci A. Sami Bayram Ozgur Ozyigit Cengiz Gebitekin O. Sacit Gorgul 《Journal of veterinary science (Suw?n-si, Korea)》2007,8(4):393-399
The comparison of the histologic healing and bronchopleural fistula (BPF) complications encountered with three different BS closure techniques (manual suture, stapler and manual suture plus tissue flab) after pneumonectomy in dogs was investigated for a one-month period. The dogs were separated into two groups: group I (GI) (n = 9) and group II (GII) (n = 9). Right and left pneumonectomies were performed on the animals in GI and GII, respectively. Each group was further divided into three subgroups according to BS closure technique: subgroup I (SGI) (n = 3), manual suture; subgroup II (SGII) (n = 3), stapler; and subgroup III (SGIII) (n = 3), manual suture plus tissue flab. The dogs were sacrificed after one month of observation, and the bronchial stumps were removed for histological examination. The complications observed during a one-month period following pneumonectomy in nine dogs (n = 9) were: BPF (n = 5), peri-operative cardiac arrest (n = 1), post-operative respiratory arrest (n = 1), post-operative cardiac failure (n = 1) and cardio-pulmonary failure (n = 1). Histological healing was classified as complete or incomplete healing. Histological healing and BPF complications in the subgroups were analyzed statistically. There was no significant difference in histological healing between SGI and SGIII (p = 1.00; p > 0.05), nor between SGII and SGIII (p = 1.00; p > 0.05). Similarly, no significant difference was observed between the subgroups in terms of BPF (p = 0.945; p > 0.05). The results of the statistical analysis indicated that manual suture, stapler or manual suture plus tissue flab could be alternative methods for BS closure following pneumonectomy in dogs. 相似文献
138.
The within-plant distribution of the cassava green spider mite, Mononychellus tanajoa Bondar, and the anatomical characteristics and the chemical components relating to varietal resistance of cassava, were studied using 11 cassava genotypes with varying levels of resistance for two dry seasons and one wet season. The results show that M. tanajoa aggregates on the top leaves of cassava at low levels of resistance as compared with a more even within-plant distribution at higher levels of resistance. Thus, for accurate sampling of mite populations, it might be important to consider young and old leaves, not just the young leaves, in fields containing resistant and susceptible cassava genotypes. Correlations between the anatomical characteristics and mite population density and damage scores were not consistent across months, either within or over seasons. This suggests that leaf anatomical characteristics may not be important in the varietal resistance of cassava to M. tanajoa. During the dry season, mite population density was positively correlated with leaf nitrogen, potassium and phosphorus and negatively correlated with leaf calcium and fat. Only calcium was negatively associated with mite damage at the peak of the dry season (January 1993 and 1994). Breeding cassava genotypes with high levels of leaf calcium and fat, and low levels of leaf nitrogen, potassium and phosphorus, may improve the level of resistance to M. tanajoa. 相似文献
139.
R B Truscott O Onoviran H L Ruhnke N A Fish C A Barker 《Canadian journal of veterinary research》1975,39(4):416-420
The in vitro antimicrobial sensitivity of 14 mycoplasma and 13 ureaplasma strains isolated from the genital tracts of bulls was examined. It was found that at relatively low concentrations, tetracycline, declomycin and tylosin were lethal to both types of organisms. Lincospectin, berenil, streptomycin and erythromycin were lethal to mycoplasmas but were only inhibitory to the ureaplasma strains at the same concentrations. Polymyxin B and novobiocin were ineffective at the levels tested. 相似文献
140.