全文获取类型
收费全文 | 1105篇 |
免费 | 111篇 |
专业分类
林业 | 55篇 |
农学 | 24篇 |
基础科学 | 1篇 |
207篇 | |
综合类 | 86篇 |
农作物 | 53篇 |
水产渔业 | 50篇 |
畜牧兽医 | 598篇 |
园艺 | 32篇 |
植物保护 | 110篇 |
出版年
2023年 | 12篇 |
2022年 | 9篇 |
2021年 | 37篇 |
2020年 | 28篇 |
2019年 | 46篇 |
2018年 | 29篇 |
2017年 | 30篇 |
2016年 | 24篇 |
2015年 | 26篇 |
2014年 | 41篇 |
2013年 | 49篇 |
2012年 | 79篇 |
2011年 | 88篇 |
2010年 | 44篇 |
2009年 | 43篇 |
2008年 | 84篇 |
2007年 | 76篇 |
2006年 | 62篇 |
2005年 | 55篇 |
2004年 | 56篇 |
2003年 | 43篇 |
2002年 | 50篇 |
2001年 | 14篇 |
2000年 | 7篇 |
1999年 | 9篇 |
1998年 | 6篇 |
1997年 | 5篇 |
1996年 | 7篇 |
1995年 | 9篇 |
1993年 | 5篇 |
1989年 | 6篇 |
1988年 | 4篇 |
1985年 | 4篇 |
1984年 | 5篇 |
1983年 | 6篇 |
1980年 | 4篇 |
1979年 | 3篇 |
1978年 | 3篇 |
1977年 | 5篇 |
1967年 | 6篇 |
1966年 | 4篇 |
1964年 | 3篇 |
1963年 | 4篇 |
1962年 | 5篇 |
1961年 | 5篇 |
1960年 | 8篇 |
1959年 | 7篇 |
1958年 | 5篇 |
1955年 | 8篇 |
1932年 | 4篇 |
排序方式: 共有1216条查询结果,搜索用时 31 毫秒
11.
Retrospective evaluation of the effect of high flow oxygen therapy delivered by nasal cannula on PaO2 in dogs with moderate‐to‐severe hypoxemia 下载免费PDF全文
12.
Adin DB Maisenbacher HW Ojeda N Fiorello CV Estrada AH Prosek R Citino SB 《American journal of veterinary research》2007,68(2):148-152
OBJECTIVE: To determine ECG and echocardiographic measurements in healthy anesthetized Grevy's zebras (Equus grevyi). ANIMALS: 20 healthy zebras. PROCEDURES: Auscultation, base-apex ECG, and echocardiography were performed on anesthetized zebras. RESULTS: Low-grade systolic murmurs were detected in the left basilar region in 4 of 20 zebras. Evaluation of ECGs from 19 zebras revealed sinus rhythm with a predominantly negative QRS complex and a mean +/- SD heart rate of 67 +/- 10 beats/min. Echocardiograms of sufficient image quality were obtained for 16 zebras. Interventricular septal thickness in diastole, left ventricular chamber in diastole and systole, left atrial diameter, and left ventricular mass were significantly and moderately correlated with estimated body weight (r values ranged from 0.650 to 0.884). Detectable swirling of blood in the right and sometimes the left ventricles was detected in 9 of 16 zebras, whereas physiologic regurgitation of blood was detected for the aortic valve in 3 zebras, pulmonary valve in 2 zebras, mitral valve in 2 zebras, and tricuspid valve in 1 zebra. CONCLUSIONS AND CLINICAL RELEVANCE: Results of this study provide reference information for use in the cardiac evaluation of anesthetized Grevy's zebras. 相似文献
13.
Greiner M Müller-Graf C Hiller P Schrader C Gervelmeyer A Ellerbroek L Appel B 《Berliner und Münchener tier?rztliche Wochenschrift》2007,120(3-4):98-107
According to current scientific opinion the risk of human infection with H5N1 via preparation and consumption of poultry meat is negligible.This opinion has not yet been challenged by a formal risk assessment, due to the lack of empirical data. We have developed a scenario pathway model as a conceptual framework for a formal assessment of the H5N1 risk to humans through consumption of poultry meat and parameterise the model using information derived from expert opinions. The aim of this study was to investigate whether the notion of an overall negligible risk via the oral infection route is consistent with ad hoc data and expert opinions on the relevant parameters of the model.The model is mainly based on expert opinion. A stochastic Monte-Carlo simulation was conducted which took into consideration (amongst others) the exposure and infection of chicken (broiler and layer), turkeys, ducks and geese, the probabilities of detection prior to slaughter, virus survival and contamination during slaughter, as well as during the cutting and preparation of meat in commercial plants and in private households, respectively. The empirical consumption pattern for poultry meat in Germany was taken into account in the simulation.The results show that the risk for the individual consumer is practically zero whereas up to 23 cases per year in Germany might occur if the upper (more pessimistic) ranges of the expert opinions apply.The finding of a low but non-negligible risk to the population is discussed in relation to the epidemiological information available from recent outbreaks in South East Asia. 相似文献
14.
Hampel V Schwarz B Kempf C Köstlin R Schillinger U Küchenhoff H Fenske N Brill T Hirschberger J 《Journal of veterinary internal medicine / American College of Veterinary Internal Medicine》2007,21(6):1340-1346
BACKGROUND: Recombinant feline interferon-omega (rFeIFN-omega) was tested as a treatment option for cats with fibrosarcoma to assess safety and feasibility. HYPOTHESIS: Treatment with rFeIFN-omega in cats with fibrosarcoma is safe and feasible. ANIMALS: Twenty domestic cats. METHODS: In an open-labeled uncontrolled clinical trial 12 injections of 1 x 10(6) U/kg rFeIFN-omega were administered over a 5-week period: the 1st through 4th injections were given intratumorally, and the 5th through 12th injections were administered subcutaneously at the tumor excision site. Wide surgical excision of the tumors was carried out after the 4th injection and before the 5th injection of rFeIFN-omega. A Common Terminology Criteria for Adverse Events (CTCAE) analysis was conducted. Flow cytometry of fibrosarcoma cells after incubation with rFeIFN-omega and recombinant feline interferon-gamma was performed to assess the biological effect of rFeIFN-omega. RESULTS: Changes in blood cell count, increases in serum aspartate-amino-transferase activity, serum bilirubin concentration, serum creatinine and serum electrolyte concentrations, weight loss, anorexia, increased body temperature, and reduced general condition were observed but were mostly minor (grade 1 and 2) and self limiting. Eosinophilia (P = .025), neutropenia (P = .021), and weight loss (P < .001) were statistically correlated with rFeIFN-omega-treatment (analysis of parameters before treatment and after 3 injections of rFeIFN-omega). Flow cytometry of 5 unrelated feline fibrosarcoma cell lines showed increased expression of major histocompatibility complex (MHC) class I molecules (P = .026) in response to in vitro incubation with rFeIFN-omega, whereas expression of MHC class II molecules was not affected significantly. CONCLUSIONS AND CLINICAL IMPORTANCE: RFeIFN-omega for the treatment of feline fibrosarcoma is safe, well tolerated, and can be easily performed in practice. To assess the efficacy of the treatment, it should be tested in a placebo-controlled trial. 相似文献
15.
Dominik Gloe Hans Mielke Christine Müller-Graf Christian Sieke 《Pest management science》2023,79(7):2372-2379
BACKGROUND
The proportionality principle has been broadly used for over 10 years in regulatory assessments of pesticide residues. It allows extrapolation of supervised field trial data conducted at lower or higher application rates compared to the use pattern under evaluation by adjustment of measured concentrations, assuming direct proportionality between the rates applied and the resulting residues. This work revisits the principle idea by using supervised residue trials sets conducted under identical conditions but with deviating application rates. Four different statistical methods were used to investigate the relationship between application rates and residue concentrations and to draw conclusions on the statistical significance of the direct proportionality assumed.RESULTS
Based on over 5000 individual trial results, the assumption of direct proportionality was not confirmed to be statistically significant (P > 0.05) using three models: direct comparison of application rates and residue concentrations ratios and two linear log-log regression models correlating application rate and residue concentration or only residue concentrations per se. In addition, a fourth model analysed deviations between expected concentrations following direct proportional adjustment and measured residue values from corresponding field trials. In 56% of all cases, the deviation was larger than ±25%, which represents the tolerance usually accepted for the selection of supervised field trials in regulatory assessments.CONCLUSION
Overall, the assumption of direct proportionality between application rates and resulting residue concentrations of pesticides was not statistically significant. Although the proportionality approach is highly pragmatic in regulatory practice, its use should be considered carefully on a case-by-case basis. © 2023 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry. 相似文献16.
Clayton T Larue Joel E Ream Xuefeng Zhou Farhard Moshiri Arlene Howe Michael Goley Oscar C Sparks Steven T Voss Erin Hall Christine Ellis Janice Weihe Qungang Qi Daniela Ribeiro Xiaoping Wei Shirley Guo Artem G Evdokimov Marguerite J Varagona James K Roberts 《Pest management science》2020,76(3):1031-1038
17.
18.
Gene expression pattern of digestive and antioxidant enzymes during the larval development of reared Atlantic bluefin tuna (ABFT), Thunnus thynnus L. 下载免费PDF全文
19.
Plants of the family Brassicaceae contain high levels of glucosinolates. The latter compounds are degraded to isothiocyanates, some of which have been shown to be potent inducers of phase II detoxification enzymes in vitro. In the present study, the ability of six plant-derived isothiocyanates (allyl isothiocyanate, iberverin, erucin, sulforaphane, iberin, and cheirolin) to increase tissue levels of the phase II detoxification enzymes quinone reductase (QR) and glutathione S-transferase (GST) in a variety of rat tissues has been compared. At the low dose level employed (40 micromol/kg/day), cheirolin was without effect in any tissue. All of the other isothiocyanates, however, increased GST and QR activities in the duodenum, forestomach, and/or the urinary bladder of the animals, with the greatest effects being seen in the urinary bladder. With the exception of cheirolin, little difference was observed in the inductive activity of the various isothiocyanates. Phase II enzymes are known to protect against chemical carcinogenesis, and the selectivity of isothiocyanates in inducing such enzymes in the bladder is of interest in view of recent epidemiological studies showing a decreased incidence of cancer of this organ in individuals with a high dietary intake of Brassica vegetables. 相似文献
20.
Bellion P Hofmann T Pool-Zobel BL Will F Dietrich H Knaup B Richling E Baum M Eisenbrand G Janzowski C 《Journal of agricultural and food chemistry》2008,56(15):6310-6317
Apples represent a major dietary source of antioxidative polyphenols. Their metabolic conversion by the gut microflora might generate products that protect the intestine against oxidative damage. We studied the antioxidant effectiveness of supernatants of fermented apple juice extracts (F-AEs, 6 and 24 h fermentation) and of selected phenolic degradation products, identified by HPLC-DAD-ESI-MS. Cell free antioxidant capacity of unfermented apple juice extracts (AEs) was decreased after fermentation by 30-50%. In the human colon carcinoma cell line Caco-2, F-AEs (containing <0.5% of original AE-phenolics) decreased the reactive oxygen species (ROS) level more efficiently than the F-blank (fermented without AE) but were less effective than the respective AEs. Similarly, antioxidant effectiveness of individual degradation products was lower compared to respective AE constituents. Glutathione level was slightly increased and oxidative DNA damage slightly decreased by fermented AE03, rich in quercetin glycosides. In conclusion, F-AEs/degradation products exhibit antioxidant activity in colon cells but to a lesser extent than the respective unfermented AEs/constituents. 相似文献