全文获取类型
收费全文 | 370篇 |
免费 | 21篇 |
专业分类
林业 | 31篇 |
农学 | 8篇 |
基础科学 | 1篇 |
78篇 | |
综合类 | 15篇 |
农作物 | 22篇 |
水产渔业 | 24篇 |
畜牧兽医 | 163篇 |
园艺 | 17篇 |
植物保护 | 32篇 |
出版年
2023年 | 3篇 |
2022年 | 3篇 |
2021年 | 1篇 |
2020年 | 6篇 |
2019年 | 7篇 |
2018年 | 6篇 |
2017年 | 4篇 |
2016年 | 14篇 |
2015年 | 7篇 |
2014年 | 16篇 |
2013年 | 14篇 |
2012年 | 30篇 |
2011年 | 34篇 |
2010年 | 14篇 |
2009年 | 19篇 |
2008年 | 34篇 |
2007年 | 30篇 |
2006年 | 17篇 |
2005年 | 21篇 |
2004年 | 11篇 |
2003年 | 20篇 |
2002年 | 20篇 |
2001年 | 9篇 |
2000年 | 7篇 |
1999年 | 4篇 |
1998年 | 4篇 |
1997年 | 5篇 |
1996年 | 2篇 |
1995年 | 3篇 |
1993年 | 6篇 |
1992年 | 2篇 |
1991年 | 3篇 |
1990年 | 3篇 |
1989年 | 2篇 |
1988年 | 2篇 |
1987年 | 2篇 |
1985年 | 2篇 |
1984年 | 1篇 |
1981年 | 1篇 |
1967年 | 1篇 |
1966年 | 1篇 |
排序方式: 共有391条查询结果,搜索用时 31 毫秒
31.
Arnaud Grüss David M. Kaplan Sylvie Guénette Callum M. Roberts Louis W. Botsford 《Biological conservation》2011,(2):692-702
Adult and juvenile mobility has a considerable influence on the functioning of marine protected areas. It is recognized that adult and juvenile movement reduces the core benefits of protected areas, namely protecting the full age–structure of marine populations, while at the same time perhaps improving fisheries yield over the no-reserve situation through export of individuals from protected areas. Nevertheless, the study of the consequences of movement on protected area functioning is unbalanced. Significant attention has been paid to the influence of certain movement patterns, such as diffusive movement and home ranges, while the impacts of others, such as density-dependent movements and ontogenetic migrations, have been relatively ignored. Here we review the diversity of density-independent and density-dependent movement patterns, as well as what is currently known about their consequences for the conservation and fisheries effects of marine protected areas. We highlight a number of ‘partially addressed’ issues in marine protected area research, such as the effects of reserves targeting specific life phases, and a number of essentially unstudied issues, such as density-dependent movements, nomadism, ontogenetic migrations, behavioral polymorphism and ‘dynamic’ reserves that adjust location as a realtime response to habitat changes. Assessing these issues will be essential to creating effective marine protected area networks for mobile species and accurately assessing reserve impacts on these species. 相似文献
32.
Bourin M Gautron J Berges M Attucci S Le Blay G Labas V Nys Y Rehault-Godbert S 《Journal of agricultural and food chemistry》2011,59(23):12368-12374
Chicken egg ovoinhibitor is a multidomain Kazal-type serine protease inhibitor with unknown function. Comparison of expression between different tissues indicated that ovoinhibitor is highly expressed in the magnum and liver followed by the uterus, which secrete egg white, egg yolk, and eggshell precursors, respectively. The results also revealed that ovoinhibitor expression is increased in the liver during sexual maturation followed by a subsequent decrease in mature hens. Ovoinhibitor was purified from the egg yolk plasma from nonfertilized eggs using two consecutive affinity chromatographies and gel filtration. Purified egg yolk ovoinhibitor was shown to inhibit trypsin and subtilisin. It was shown that purified egg yolk ovoinhibitor exhibited antimicrobial activities against Bacillus thuringiensis . The results suggest that this anti-protease plays a significant role in antibacterial egg defense against Bacillus spp., preventing contamination of table eggs (nonfertilized eggs) and protecting the chick embryo (fertilized eggs). 相似文献
33.
Gagnaire V Carpino S Pediliggieri C Jardin J Lortal S Licitra G 《Journal of agricultural and food chemistry》2011,59(23):12443-12452
Ragusano is a pasta filata cheese produced from raw milk in Sicily. The proteolysis was extensively analyzed after stretching (day 0), at 4 and 7 months of ripening through soluble nitrogen, urea-PAGE, and peptide identification by tandem mass spectrometry. After stretching, 123 peptides were identified: 72 arising from β-casein, 34 from α(s1)-casein, and 17 from α(s2)-casein. The main protein splitting corresponded to the action of plasmin, chymosin, cathepsin D, cell envelope proteinase, and peptidase activities of lactic acid bacteria. Unlike other types of cheeses, <10% residual β- and α(s)-caseins remained intact at 7 months, indicating original network organization based on large casein fragments. The number of identified soluble peptides also dramatically decreased after 4 and 7 months of ripening, to 47 and 25, respectively. Among them, bioactive peptides were found, that is, mineral carrier, antihypertensive, and immunomodulating peptides and phosphopeptides. 相似文献
34.
Defauw PA Van de Maele I Duchateau L Polis IE Saunders JH Daminet S 《Journal of Feline Medicine and Surgery》2011,13(12):967-975
Feline idiopathic cystitis (FIC) is the most common cause of feline lower urinary tract disease (FLUTD). This retrospective, case-controlled study evaluated possible risk factors associated with FIC and compared different clinical presentations in 64 cats with FIC. Several risk factors known to be involved in FLUTD were identified as playing a role in FIC. Of the stressful situations considered, most did not occur with increased frequency in cats with FIC compared to controls, except for a house move. The presence of pyuria, haematuria and an increased urine protein:creatinine ratio were significantly higher in obstructed males compared with non-obstructed males. An obstruction was significantly more likely in cats with struvite crystalluria compared with cats without struvite crystalluria. These findings suggest that urethral plugs might be an important cause or contributing factor of obstruction in FIC. Episodes of FIC seem to occur mainly in susceptible cats in combination with a deficient environment. 相似文献
35.
Adrien Gallou Hernán Patricio Lucero Mosquera Sylvie Cranenbrouck Juan Pablo Suárez Stéphane Declerck 《Physiological and Molecular Plant Pathology》2011,76(1):20-26
Biological control of soil-borne pathogens by arbuscular mycorrhizal (AM) fungi has been repeatedly demonstrated. However, their role in the control of above-ground hemibiotrophic pathogens is less conclusive. Here, we investigated in vitro the impact of an AM fungus on Phytophthora infestans in potato plants. The leaf infection index was decreased in mycorrhizal potato plants. Real-Time Quantitative PCR revealed the induction of two pathogenesis related genes (PR1 and PR2) in the leaves of mycorrhizal plants shortly after infection with P. infestans. These results suggested a systemic resistance in mycorrhizal plants, related to the priming of the two PR genes in potato. 相似文献
36.
The effects of canopy, soil physico-chemical and microbiological variables on Sclerotinia stem rot (SSR) on soybean were assessed in two soils (clay loam and sandy loam) using multiple regression and canonical redundancy analysis (RDA) and their partial form to control for the rotation (2 or 3-y-corn/soybean monoculture) and fertilization (mineral/urban compost) or spatial variables effects. The models revealed the minimal sets of variables that best explain the variance of the survival of Sclerotinia sclerotiorum’s sclerotia, carpogenic germination, disease severity and their associations. In clay loam, the 3-y-corn rotation reduced disease severity mainly through the reduction of weed biomass that favoured carpogenic germination. Urban compost has a conducive effect explained by a better soil surface drainage. Additionally, total N was found suppressive to sclerotial survival. In sandy loam, the carpogenic germination was negatively correlated with high C mineralization quotient and aggregate stability but correlated positively with Ca. Sclerotial survival was negatively correlated with pH and Ca, and positively correlated with biological fertility index. Aggregate stability, Ca and pH were associated with the urban compost. The regression and RDA analyses allowed to identify key variables that drived SSR development and explain their relationship with the cultural practices, soil health, as well as the spatial variation of disease variables. 相似文献
37.
A J Roussel N D Cohen R N Hooper P C Rakestraw 《Journal of the American Veterinary Medical Association》2001,219(1):72-78
OBJECTIVE: To determine risk factors associated with development of postoperative ileus in horses undergoing surgery for colic. DESIGN: Case-control study. ANIMALS: 69 horses that developed ileus after surgery for colic and 307 horses that did not develop postoperative ileus. PROCEDURE: Signalment, history, clinicopathologic data, treatment, lesions, and outcome were obtained from medical records. RESULTS: Variables associated with increased risk of postoperative ileus included age > 10 years, Arabian breed, PCV > or = 45%, high serum concentrations of protein and albumin, anesthesia > 2.5 hours' duration, surgery > 2 hours' duration, resection and anastomosis, and lesions in the small intestine. Enterotomy reduced the risk of postoperative ileus. After multivariate logistic regression, the final model included the variables Arabian breed, PCV > or = 45%, lesion type, duration of surgery (> 2 hours vs < or = 2 hours), and pelvic flexure enterotomy. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that by evaluating certain factors, horses at increased risk of postoperative ileus may be recognized before the condition develops. Preventative treatment and early intervention may be instituted in these horses. Shortening surgery time and performing an enterotomy may decrease the probability of horses developing postoperative ileus. 相似文献
38.
G W Brumbaugh P F Frelier A J Roussel T D Thomson 《American journal of veterinary research》1992,53(4):544-546
Monensin sodium (0, 15, or 30 mg/kg of complete feed) was fed ad libitum for 1 week to female mice (strain C57BL6/J) that were genetically susceptible to infection with Mycobacterium paratuberculosis. Ten mice in each of the 3 groups were inoculated intraperitoneally with M paratuberculosis (10(9) organisms). Sterile saline solution was injected intraperitoneally into 10 other mice in each group. Rations were continued for 50 days, then mice were euthanatized, and body weight, splenic weight, and hepatic weight for each mouse were recorded. Ratios of body weight to splenic weight and of body weight to hepatic weight were calculated for each mouse. Hepatic granulomas in 50 light microscopic fields were counted, and presence of acid-fast organisms in those granulomas was recorded. Infected mice given monensin had higher body weight and fewer hepatic granulomas than did mice not given monensin. Although hepatic granulomas were fewer in these mice, they contained acid-fast organisms. Effects of 15 mg of monensin and those of 30 mg of monensin/kg of complete feed were not different. 相似文献
39.
40.
ABSTRACT Mapping and analyzing the disease status of individual plants within a study area at successive dates can give insight into the processes involved in the spread of a disease. We propose a permutation method to analyze such spatiotemporal maps of binary data (healthy or diseased plants) in regularly spaced plantings. It requires little prior information on the causes of disease spread and handles missing plants and censored data. A Monte Carlo test is used to assess whether the location of newly diseased plants is independent of the location of previously diseased plants. The test takes account of the significant spatial structures at each date in order to separate nonrandomness caused by the structure at one date from nonrandomness caused by the dependence between newly diseased plants and previously diseased plants. If there is a nonrandom structure at both dates, independent patterns are simulated by randomly shifting the entire pattern observed at the second date. Otherwise, independent patterns are simulated by randomly reallocating the positions of one group of diseased plants. Simulated and observed patterns of disease are then compared through distance-based statistics. The performance of the method and its robustness are evaluated by its ability to accurately identify simulated independent and dependent bivariate point patterns. Additionally, two realworld spatiotemporal maps with contrasting disease progress illustrate how the tests can provide valuable clues about the processes of disease spread. This method can supplement biological investigations and be used as an exploratory step before developing a specific mechanistic model. 相似文献