全文获取类型
收费全文 | 538篇 |
免费 | 54篇 |
国内免费 | 2篇 |
专业分类
林业 | 43篇 |
农学 | 25篇 |
基础科学 | 2篇 |
88篇 | |
综合类 | 59篇 |
农作物 | 34篇 |
水产渔业 | 35篇 |
畜牧兽医 | 227篇 |
园艺 | 19篇 |
植物保护 | 62篇 |
出版年
2020年 | 5篇 |
2019年 | 4篇 |
2018年 | 16篇 |
2017年 | 11篇 |
2016年 | 16篇 |
2015年 | 10篇 |
2014年 | 11篇 |
2013年 | 42篇 |
2012年 | 25篇 |
2011年 | 30篇 |
2010年 | 19篇 |
2009年 | 19篇 |
2008年 | 24篇 |
2007年 | 27篇 |
2006年 | 30篇 |
2005年 | 29篇 |
2004年 | 25篇 |
2003年 | 27篇 |
2002年 | 26篇 |
2001年 | 5篇 |
2000年 | 4篇 |
1999年 | 7篇 |
1998年 | 6篇 |
1997年 | 7篇 |
1996年 | 4篇 |
1995年 | 8篇 |
1994年 | 5篇 |
1993年 | 5篇 |
1992年 | 6篇 |
1991年 | 3篇 |
1990年 | 8篇 |
1989年 | 4篇 |
1988年 | 10篇 |
1987年 | 4篇 |
1986年 | 6篇 |
1985年 | 6篇 |
1984年 | 7篇 |
1983年 | 4篇 |
1981年 | 6篇 |
1977年 | 4篇 |
1974年 | 3篇 |
1973年 | 9篇 |
1972年 | 3篇 |
1971年 | 3篇 |
1970年 | 4篇 |
1967年 | 3篇 |
1964年 | 4篇 |
1963年 | 4篇 |
1962年 | 3篇 |
1955年 | 5篇 |
排序方式: 共有594条查询结果,搜索用时 171 毫秒
71.
Two trials were conducted with lambs to evaluate the growth promoting effects of selenium administered orally at a level of 5 mg per month during the pasture season.
No statistically significant effect on weight gains was found to be attributable to selenium administration in either the single lamb or the twin lamb experiment. In both trials there was a trend in the data that suggested a deleterious effect of selenium on weight gains.
相似文献72.
Harland W. Renshaw John W. Gessner Lynn F. Woodard Dale O. Everson 《Veterinary microbiology》1983,8(3):281-291
Miniature swine (n = 5 per group) were inoculated intradermally with mineral oil-in-water emulsions containing either 150 μg of mycobacterial immunopotentiating glyco-lipid P3 (EP3), 150 μg of lyophilized Mycobacterium avium (serotype 8) cell walls (E-MaCW), or 150 μg P3 and 150 μg M. avium cell walls (EP3-MaCW). Swine vaccinated with E-MaCW and EP3-MaCW developed antigen-sensitive lymphocytes detectable with delayed-type hypersensitivity (DTH) skin tests and lymphocyte transformation assay. Swine injected with EP3 were not sensitized. In general EP3-MaCW evoked a more pronounced in vivo DTH tuberculin skin test and in vitro lymphocyte transformation responses than E-MaCW. Time-course studies indicated a more persistent response in swine injected with EP3-MaCW than in those given E-MaCW. Commercial type Yorkshire swine (n = 5) inoculated intradermally with EP3-MaCW developed cell-mediated immune (CMI) responses to avian tuberculin detectable in vivo with delayed-type skin hypersensitivity and in vitro with lymphocyte immunostimulation responses. 相似文献
73.
Imidazolinone-tolerant crops: history, current status and future 总被引:15,自引:0,他引:15
Imidazolinone herbicides, which include imazapyr, imazapic, imazethapyr, imazamox, imazamethabenz and imazaquin, control weeds by inhibiting the enzyme acetohydroxyacid synthase (AHAS), also called acetolactate synthase (ALS). AHAS is a critical enzyme for the biosynthesis of branched-chain amino acids in plants. Several variant AHAS genes conferring imidazolinone tolerance were discovered in plants through mutagenesis and selection, and were used to create imidazolinone-tolerant maize (Zea mays L), wheat (Triticum aestivum L), rice (Oryza sativa L), oilseed rape (Brassica napus L) and sunflower (Helianthus annuus L). These crops were developed using conventional breeding methods and commercialized as Clearfield* crops from 1992 to the present. Imidazolinone herbicides control a broad spectrum of grass and broadleaf weeds in imidazolinone-tolerant crops, including weeds that are closely related to the crop itself and some key parasitic weeds. Imidazolinone-tolerant crops may also prevent rotational crop injury and injury caused by interaction between AHAS-inhibiting herbicides and insecticides. A single target-site mutation in the AHAS gene may confer tolerance to AHAS-inhibiting herbicides, so that it is technically possible to develop the imidazolinone-tolerance trait in many crops. Activities are currently directed toward the continued improvement of imidazolinone tolerance and development of new Clearfield* crops. Management of herbicide-resistant weeds and gene flow from crops to weeds are issues that must be considered with the development of any herbicide-resistant crop. Thus extensive stewardship programs have been developed to address these issues for Clearfield* crops. 相似文献
74.
75.
76.
77.
78.
Adams WM Bjorling DE McAnulty JE Green EM Forrest LJ Vail DM 《Journal of the American Veterinary Medical Association》2005,227(6):936-941
OBJECTIVE: To compare long-term results of radiotherapy alone versus radiotherapy followed by exenteration of the nasal cavity in dogs with malignant intranasal neoplasia. DESIGN: Retrospective study. ANIMALS: 53 dogs with malignant intranasal neoplasia. PROCEDURE: All dogs underwent radiotherapy consisting of administration of 10 fractions of 4.2 Gy each on consecutive weekdays. For dogs in the surgery group (n=13), follow-up computed tomography was performed, and dogs were scheduled for surgery if persistent or recurrent tumor was seen. RESULTS: Perioperative complications for dogs that underwent surgery included hemorrhage requiring transfusion (2 dogs) and subcutaneous emphysema (8). Rhinitis and osteomyelitis-osteonecrosis occurred significantly more frequently in dogs in the radiotherapy and surgery group (9 and 4 dogs, respectively) than in dogs in the radiotherapy-only group (4 and 3 dogs, respectively). Two- and 3-year survival rates were 44% and 24%, respectively, for dogs in the radiotherapy group and 69% and 58%, respectively, for dogs in the surgery group. Overall median survival time for dogs in the radiotherapy and surgery group (477 months) was significantly longer than time for dogs in the radiotherapy-only group (19.7 months). CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that exenteration of the nasal cavity significantly prolongs survival time in dogs with intranasal neoplasia that have undergone radiotherapy. Exenteration after radiotherapy may increase the risk of chronic complications. 相似文献
79.
ABSTRACT Plants can be induced to develop enhanced resistance to pathogen infection by treatment with a variety of abiotic and biotic inducers. Biotic inducers include infection by necrotizing pathogens and plant-growth-promoting rhizobacteria, and treatment with nonpathogens or cell wall fragments. Abiotic inducers include chemicals which act at various points in the signaling pathways involved in disease resistance, as well as water stress, heat shock, and pH stress. Resistance induced by these agents (resistance elicitors) is broad spectrum and long lasting, but rarely provides complete control of infection, with many resistance elicitors providing between 20 and 85% disease control. There also are many reports of resistance elicitors providing no significant disease control. In the field, expression of induced resistance is likely to be influenced by the environment, genotype, and crop nutrition. Unfortunately, little information is available on the influence of these factors on expression of induced resistance. In order to maximize the efficacy of resistance elicitors, a greater understanding of these interactions is required. It also will be important to determine how induced resistance can best fit into disease control strategies because they are not, and should not be, deployed simply as "safe fungicides". This, in turn, will require information on the interaction of resistance elicitors with crop management practices such as appropriate-dose fungicide use. 相似文献
80.