全文获取类型
收费全文 | 2588篇 |
免费 | 181篇 |
国内免费 | 4篇 |
专业分类
林业 | 190篇 |
农学 | 54篇 |
基础科学 | 13篇 |
539篇 | |
综合类 | 246篇 |
农作物 | 139篇 |
水产渔业 | 220篇 |
畜牧兽医 | 1113篇 |
园艺 | 81篇 |
植物保护 | 178篇 |
出版年
2024年 | 11篇 |
2023年 | 46篇 |
2022年 | 52篇 |
2021年 | 120篇 |
2020年 | 121篇 |
2019年 | 125篇 |
2018年 | 97篇 |
2017年 | 95篇 |
2016年 | 100篇 |
2015年 | 92篇 |
2014年 | 96篇 |
2013年 | 102篇 |
2012年 | 203篇 |
2011年 | 246篇 |
2010年 | 114篇 |
2009年 | 105篇 |
2008年 | 185篇 |
2007年 | 162篇 |
2006年 | 141篇 |
2005年 | 107篇 |
2004年 | 100篇 |
2003年 | 96篇 |
2002年 | 93篇 |
2001年 | 12篇 |
2000年 | 14篇 |
1999年 | 11篇 |
1998年 | 10篇 |
1997年 | 6篇 |
1996年 | 6篇 |
1995年 | 9篇 |
1994年 | 10篇 |
1993年 | 11篇 |
1992年 | 4篇 |
1991年 | 4篇 |
1990年 | 5篇 |
1989年 | 6篇 |
1988年 | 4篇 |
1987年 | 6篇 |
1984年 | 2篇 |
1981年 | 3篇 |
1980年 | 2篇 |
1955年 | 3篇 |
1951年 | 2篇 |
1950年 | 5篇 |
1949年 | 3篇 |
1943年 | 2篇 |
1942年 | 2篇 |
1941年 | 4篇 |
1940年 | 2篇 |
1939年 | 3篇 |
排序方式: 共有2773条查询结果,搜索用时 15 毫秒
81.
Goddeeris BM 《Veterinary immunology and immunopathology》2002,87(3-4):391-394
A few reflections are made on the future strategies and approaches for combating infectious diseases of livestock, keeping into consideration public concern on food quality and availability. The policy of eradication of pathogens/diseases instead of vaccination has rendered livestock naive to certain pathogens and as a consequence susceptible to epidemic outbreaks, even more so as we have to conclude that outside attack is quite often difficult to control. Therefore, immunoprophylactic measures in livestock remain top priority and will in the future focus more on the induction of mucosal immunity and the activation of innate immunity. 相似文献
82.
Hinton LE McLoughlin MA Johnson SE Weisbrode SE 《Journal of the American Animal Hospital Association》2002,38(2):176-187
The records of 23 dogs and cats diagnosed with spontaneous gastroduodenal perforation (GDP) were retrospectively reviewed. Survival was 63% in dogs and 14% in cats. Rottweilers <5 years of age were overrepresented. Clinical evidence of gastrointestinal bleeding was common in dogs but not in cats. Shock was an uncommon presenting condition in dogs and was not closely linked to outcome. In fact, progression of an ulcerating lesion to GDP was not associated with marked changes in symptoms exhibited by many patients in this study. Most GDPs were associated with histopathological evidence of subacute or chronic peritoneal reaction at the time of diagnosis. This suggests that diagnostic methods employed lacked sensitivity in identifying early perforating lesions, and that dramatic signs of acute abdomen following gastroduodenal perforation may not be as common as was previously thought. 相似文献
83.
This study determined the frequency of occurrence and the mean number of 'flame follicles' per skin section and assessed their diagnostic significance in cutaneous biopsies of Shar-pei dogs. The number of 'flame follicles' per section was recorded in skin sections from 42 Shar-pei dogs, of which 40 had non-neoplastic skin disease and non-atrophic dermatoses and 2 had healthy skin. Forty-two skin sections from dogs of different breeds served as control specimens, 28 of which were examples of non-neoplastic and non-atrophic dermatoses and 14 were from dogs with healthy skin. Differences among groups were analysed by means of the unpaired Student's t-test. It was concluded that 'flame follicles' were more frequent and found in significantly higher numbers in the Shar-pei group when compared with the control group suggesting that 'flame follicles' in skin sections from Shar-pei dogs do not have the same diagnostic significance as in other breeds. 相似文献
84.
Interactions between Plasmopara helianthi, Glomus mosseae and Two Plant Activators in Sunflower Plants 总被引:1,自引:0,他引:1
Laura Tosi Antonio Zazzerini 《European journal of plant pathology / European Foundation for Plant Pathology》2000,106(8):735-744
Interactions between Plasmopara helianthi, Glomus mosseae and two plant activators DL--amino-n-butyric acid (BABA) and CGA 245704 (acibenzolar-S-methyl (BTH)) in sunflower plants susceptible to downy mildew were studied in four experiments using different methods of treatment and pathogen inoculation. Both chemicals were applied as soil drenches and foliar sprays, whereas P. helianthi infection was obtained by root and cotyledon inoculations of the seedlings. Soil drenches at the rates of 50 and 100mgkg–1 soil of BABA and BTH given 1 and 3 days before P. helianthi inoculation, respectively to mycorrhizal plants, provided moderate protection against the pathogen (about 50–55%). Morphological changes and decrease in mycorrhizal colonization in roots of BTH-treated plants and in BTH-treated mycorrhizal plants were also observed. Delay in the emergence and reduction of the root systems were more evident at the highest concentration but decreased with time. These effects were absent with the BABA treatment.Foliar spray treatment of BABA and BTH, applied at 4000 and 200µgml–1, respectively (1 day post-inoculation) to mycorrhizal plants provided good protection (about 80%) against P. helianthi foliar infections. No effects on mycorrhizal colonization or on root systems were observed.
In vitro tests on the effect of the compounds on the mycorrhizal fungus showed that the germination of G. mosseae sporocarps increased with BABA treatment whereas it was greatly inhibited by BTH treatment. 相似文献
85.
Laura H Waitt Christopher K Cebra Susan J Tornquist Christiane V L?hr 《Journal of veterinary diagnostic investigation》2006,18(4):405-408
A 22-year-old pinto mixed breed mare was admitted for evaluation of severe colic signs and gastric reflux. Multiple nonpainful, variably sized hard masses were palpated in the subcutis over the thorax, abdomen, and hindquarters of the horse. The mare was diagnosed with sterile peritonitis and had systemically high gamma-glutamyltransferase, amylase, and lipase. Three days into treatment she became febrile with signs of persistent and mild abdominal discomfort; euthanasia was elected. Necropsy revealed peripancreatitis, pancreatic fibrosis, abdominal steatitis and panniculitis. Panniculitis associated with peripancreatitis has been described in humans and dogs but not in horses. Pathogenic models for this entity are discussed. 相似文献
86.
Communicating with oncology clients. 总被引:1,自引:0,他引:1
Ruthanne Chun Laura D Garrett 《Veterinary Clinics of North America: Small Animal Practice》2007,37(6):1013-22; v
Empathic, honest, and consistent communications that establish realistic goals and focus on quality of life (during and after therapy) for pets with cancer provide the basis of an excellent client-veterinarian relationship. From this foundation, a client can team up with his or her veterinarian to make the best possible decisions for the pet and for himself or herself regarding care for the companion animal. 相似文献
87.
Secondary metabolites and host defense compounds were shown to occur in xylem sap, and leaves of Vitis vinifera cv. Italia and cv. Matilde naturally infected by the esca-associated fungi Phaeomoniella chlamydospora (Pch), Togninia minima (Tmi) and Fomitiporia mediterranea (Fme). Samples of xylem sap and leaves were collected from healthy vines and from vines showing severe symptoms of brown wood-streaking caused by Pch and Tmi, or from vines with symptoms of both brown wood-streaking and white rot caused by Fme. Xylem sap collection was carried out during the early spring of 2003 and 2004, corresponding to the phenological phases: (A) cotton bud; (B) green tip; (C) leaves out; (D) stretched out leaves; and (E) visible clusters. In the present work we have studied the accumulation of biomolecules (pentaketides and α-glucans), host defense compounds (benzaldehydes, benzoic acid and cinnamic acid derivatives, flavonols, flavanols, flavan-3-ol derivatives and stilbenes) at different stages of grapevine development. Accumulation and changes in total phenolics and recurring phenolics, and of three phytotoxic secondary metabolites (scytalone, isosclerone and pullulan) were analyzed by HPLC. On comparing results for cv. Italia and cv. Matilde, it can be seen that phenolic concentrations are strongly related to the cv. 相似文献
88.
When the esca-associated fungi Phaeomoniella chlamydospora (Pch), Togninia minima (Tmi) and Fomitiporia mediterranea (Fme) were grown in liquid stationary cultures, it was seen that they were able to live in media containing resveratrol (RES) or tannic acid (TA) as the sole carbon source and that the fungi were able to convert both compounds. Particular attention is paid here to detecting RES and TA conversion. Pch, Tmi and Fme were partially inhibited by RES or TA. Pch, Tmi and Fme produced extracellular tannase, laccase and peroxidase enzymes in liquid or agarized cultures, whether glucose was present or not. When colonies of Pch, Tmi and Fme were confronted, they showed spatially and temporally heterogeneous patterns of laccase and peroxidase activity. The results indicate the non-synergistic, competitive association of Pch and Tmi and the inhibition of Fme growth. Muconic acid, a well-known intermediate in a large number of lignin and phenol oxidative processes, can partly or completely inhibit the lignolytic agent Fme, but is tolerated by Pch and Tmi. An explanation for wood pigmentation patterns by Pch, Tmi and Fme is given. 相似文献
89.
Yuri Zharikov David B. Lank Falk Huettmann Russell W. Bradley Nadine Parker Peggy P. -W. Yen Laura A. Mcfarlane-Tranquilla Fred Cooke 《Landscape Ecology》2006,21(1):107-120
We studied habitat selection and breeding success in marked populations of a protected seabird (family Alcidae), the marbled
murrelet (Brachyramphus marmoratus), in a relatively intact and a heavily logged old-growth forest landscape in south-western Canada. Murrelets used old-growth
fragments either proportionately to their size frequency distribution (intact) or they tended to nest in disproportionately
smaller fragments (logged). Multiple regression modelling showed that murrelet distribution could be explained by proximity
of nests to landscape features producing biotic and abiotic edge effects. Streams, steeper slopes and lower elevations were
selected in both landscapes, probably due to good nesting habitat conditions and easier access to nest sites. In the logged
landscape, the murrelets nested closer to recent clearcuts than would be expected. Proximity to the ocean was favoured in
the intact area. The models of habitat selection had satisfactory discriminatory ability in both landscapes. Breeding success
(probability of nest survival to the middle of the chick rearing period), inferred from nest attendance patterns by radio-tagged
parents, was modelled in the logged landscape. Survivorship was greater in areas with recent clearcuts and lower in areas
with much regrowth, i.e. it was positively correlated with recent habitat fragmentation. We conclude that marbled murrelets
can successfully breed in old-growth forests fragmented by logging. 相似文献