全文获取类型
收费全文 | 605篇 |
免费 | 72篇 |
专业分类
林业 | 41篇 |
农学 | 32篇 |
122篇 | |
综合类 | 25篇 |
农作物 | 24篇 |
水产渔业 | 102篇 |
畜牧兽医 | 285篇 |
园艺 | 13篇 |
植物保护 | 33篇 |
出版年
2023年 | 3篇 |
2022年 | 12篇 |
2021年 | 19篇 |
2020年 | 21篇 |
2019年 | 30篇 |
2018年 | 32篇 |
2017年 | 39篇 |
2016年 | 32篇 |
2015年 | 16篇 |
2014年 | 32篇 |
2013年 | 33篇 |
2012年 | 37篇 |
2011年 | 53篇 |
2010年 | 30篇 |
2009年 | 25篇 |
2008年 | 30篇 |
2007年 | 27篇 |
2006年 | 22篇 |
2005年 | 18篇 |
2004年 | 23篇 |
2003年 | 22篇 |
2002年 | 17篇 |
2001年 | 11篇 |
2000年 | 16篇 |
1999年 | 5篇 |
1998年 | 5篇 |
1997年 | 4篇 |
1996年 | 1篇 |
1995年 | 2篇 |
1994年 | 2篇 |
1993年 | 5篇 |
1992年 | 9篇 |
1991年 | 3篇 |
1990年 | 3篇 |
1989年 | 8篇 |
1988年 | 5篇 |
1987年 | 2篇 |
1986年 | 3篇 |
1985年 | 4篇 |
1984年 | 2篇 |
1983年 | 1篇 |
1982年 | 2篇 |
1981年 | 1篇 |
1978年 | 2篇 |
1977年 | 2篇 |
1976年 | 1篇 |
1975年 | 1篇 |
1972年 | 1篇 |
1971年 | 3篇 |
排序方式: 共有677条查询结果,搜索用时 125 毫秒
1.
One hundred two fecal specimens from psittacine birds submitted to Veterinary Laboratory Services of the California Department of Food and Agriculture at Petaluma were screened for Chlamydia psittaci by a direct immunofluorescence assay using a fluorescein-labeled monoclonal antibody conjugate specific for Chlamydia sp. Results were compared with those obtained by isolation of chlamydia in cultures of McCoy mouse cells. The relative specificity of the direct fluorescent antibody test on fecal smears was 98.9% and the relative sensitivity was 62.5%. The results of this study suggested that the direct fluorescent antibody test was highly specific, and it proved to be a useful same-day antemortem diagnostic test for birds with symptomatic chlamydial infection. The use of centrifugation in the cell culture assay was found to significantly enhance the level of chlamydial infection in cell culture. 相似文献
2.
Interactions between different media and follicle‐stimulating hormone supplementation on in vitro culture of preantral follicles enclosed in ovarian tissue derived from collared peccaries (Pecari tajacu Linneaus, 1758) 下载免费PDF全文
GL Lima VB Luz LF Lima RMP Rocha SV Castro TS Castelo APR Rodrigues JR Figueiredo AR Silva 《Reproduction in domestic animals》2018,53(4):880-888
The aim was to verify the effect of follicle‐stimulating hormone (FSH) supplementation to α‐MEM+ or TCM199+ media on the in vitro development of ovarian preantral follicles (PFs) derived from collared peccaries. Ovaries (n = 5 pairs) were collected and divided into fragments destined to control group (non‐cultured) or treatments that were cultured for 7 days. The PFs morphology, growth and activation were evaluated by classical histology. The immunohistochemistry markers Ag‐NOR and PCNA were used for nuclear proliferation analysis, and the picrosirius red labelling was used for ovarian extracellular matrix (ECM) evaluation. After 7‐day culture, only the TCM199+ treatment maintained the proportion of intact PFs similar to day 1 (63.2%), but no differences were found among treatments (p > .05). In addition, a significant increase in the growing follicles proportion was verified for all the treatments, indicating follicular activation (p > .05). By the Ag‐NOR analysis, only the TCM199+/FSH maintained the nuclear proliferation similar to the first day (p > .05). The picrosirius red staining revealed that the ECM remained intact in all the treatments (p > .05). We suggest the use of TCM199+ medium supplemented of FSH for the in vitro development of peccaries PFs under 7‐day culturing conditions. 相似文献
3.
S. Leal‐Soto R. Barraza‐Guardado R. Castro‐Longoria J. Chvez‐Villalba F. Hoyos‐Chirez 《Journal of the World Aquaculture Society》2011,42(6):789-800
Pen shells are economically important and most are threatened by overexploitation and habitat degradation. Cultivation represents an alternative for preserving the resource and increasing the production. Atrina maura was cultivated in a suspension system which was followed by a bottom phase. Samples of pen shells and tissues were collected monthly to measure absolute growth, shell height increase, and an adductor muscle index. After the trials, adults shell height was 195 ± 10 mm, total weight was 223 ± 28 g, and mean shell height increase was 0.81 cm/mo. Protective devices were vital to avoid predation by crabs and fish; survival was 90% in the suspension phase and 70% in the bottom phase. Variations in the muscle index were apparently related to reproduction, suggesting activity (partial spawning) from August 2008 to April 2009 in juveniles and a major spawning in adults during August 2009. Adductor muscles reached a mean of 21 g after 20 mo of cultivation, but muscle weights decreased significantly after reproduction (August to November 2009). Results indicated that A. maura is suitable for aquaculture and the cultivation system adopted here should be tested in pilot‐scale ventures. This system may work with other species of pen shells. 相似文献
4.
5.
Microdialysis measurements of equine lamellar perfusion and energy metabolism in response to physical and pharmacological manipulations of blood flow 下载免费PDF全文
6.
Rúbia Monteiro de Castro Cunha Gleidice Eunice Lavalle Fernanda Camargo Nunes Ayisa Rodrigues de Oliveira Renato de Lima Santos Roberto Baracat de Araújo 《Veterinary and comparative oncology》2023,21(2):240-254
Squamous cell carcinoma (SCC) is an important malignancy in dogs, due to its incidence and clinical presentation, which can be of locally aggressive single or multiple lesions with a metastatic potential. The objective of this investigation was to evaluate SCC response to treatment, anatomopathological and immunohistochemical characteristics, disease-free interval and overall survival time. 54 dogs with histopathologically diagnosed SCC were included in this study. Their mean age was 9.16 years with a range of 1–14 years. Of the 54 animals in the study, 34 (65.4%) had white skin and white fur coats. There was a significant correlation between fur coat colour and the development of tumours in areas of sun exposure (p = .001). Animals with tumours in areas of the body exposed to the sun had longer overall survival time than animals with tumours in areas not associated with sun exposure (p = .001). Surgery combined with electrochemotherapy (ECT) yielded a survival rate 32% higher than using a surgical approach alone (HR = 0.32, p = .038, IC = 0.11–0.94). ECT, with or without surgery, had an objective response rate of 90.9%. Local lymph node and/or distant site metastasis at diagnosis, or at some point during follow-up, occurred in 34.6% (18/52) of animals. Animals with tumours in sun exposed locations had more aggressive histopathological characteristics but had longer overall survival time. This is probably due to individualised therapeutic treatment with both surgery and ECT. 相似文献
7.
Some Limiting Factors in Superintensive Production of Juvenile Pacific White Shrimp,Litopenaeus vannamei,in No‐water‐exchange,Biofloc‐dominated Systems 下载免费PDF全文
David I. Prangnell Leandro F. Castro Abdulmehdi S. Ali Craig L. Browdy Paul V. Zimba Susan E. Laramore Tzachi M. Samocha 《Journal of the World Aquaculture Society》2016,47(3):396-413
Superintensive shrimp culture in zero‐exchange, biofloc‐dominated production systems is more biosecure and sustainable than traditional shrimp farming practices. However, successful application of this technology depends upon optimizing dietary formulations, controlling Vibrio outbreaks, and managing accumulative changes in water quality and composition. A 49‐d study investigated the effect of two commercial feeds of differing protein content and an indoor limited‐exchange, biofloc‐dominated culture environment on Litopenaeus vannamei performance and tissue composition, water quality and ionic composition, and Vibrio dynamics. Juveniles (5.3 g) were stocked at 457/m3 into four 40 m3 shallow raceways containing biofloc‐dominated water and fed one of two commercial feeds with differing protein content, 35 or 40%. Shrimp performance, Vibrio populations, and changes in shrimp and culture water composition were monitored. There were no significant differences (P > 0.05) in shrimp performance (survival, weight, growth, specific growth rate, total biomass, yield, feed conversion ratio, and protein efficiency ratio) or proximate composition between feed types. The 40% protein feed resulted in higher culture water nitrate and phosphate concentrations, alkalinity consumption and bicarbonate use, and higher phytoplankton density. The presence of Vibrio, specifically Vibrio parahaemolyticus, reduced shrimp survival. This survival decrease corresponded with increased culture water Vibrio concentrations. Culture water K+ and Mg2+ increased significantly (P < 0.05), and Sr2+, Br?, and Cl? decreased significantly (P < 0.05) over time. While Cu2+ and Zn2+ did increase in shrimp tissue, no heavy metals accumulated to problematic levels in culture water or shrimp tissue. These results demonstrate the importance of monitoring Vibrio populations and ionic composition in limited‐exchange shrimp culture systems. 相似文献
8.
L.H.S. Zobiole R.S. Oliveira R.J. Kremer J. Constantin T. Yamada C. Castro F.A. Oliveira A. Oliveira 《Applied soil ecology》2010,44(2):176-180
Decreased biological nitrogen fixation in glyphosate-resistant (GR) soybeans has been attributed directly to toxicity of glyphosate or its metabolites, to N2-fixing microorganisms. As a strong metal chelator, glyphosate could influence symbiotic N2 fixation by lowering the concentration of nickel (Ni) that is essential for the symbiotic microorganisms. Evaluation of different cultivars grown on different soil types at the State University of Maringá, PR, Brazil during the summer 2008 revealed, significant decreases in photosynthetic parameters (chlorophyll, photosynthetic rate, transpiration and stomatal conductance) and nickel content with glyphosate use (single or sequential application). This work demonstrated that glyphosate can influence the symbiotic N2 fixation by lowering nickel content available to the symbiotic microorganisms. 相似文献
9.
The epidemiology of the Neotropical rust caused by Puccinia psidii in the Indian Myrtaceae Syzygium jambos (rose apple) was investigated in central Brazil. Disease severities recorded during a 12-month period were fitted by a Fourier curve with three cyclic components or harmonics. The first, second and third harmonics accounted for 49·6, 25·9, and 1·5% of total disease measured, respectively. A highly significant linear correlation was observed between the first harmonic and the accumulated number of days having at least 6 h wetness, or a minimum of 90% relative humidity, combined with temperatures that ranged from 18 to 20°C. No significant correlation was observed between the second and third harmonics and the weather variables evaluated. Rose apple trees showed a flush of growth with new susceptible host tissue during the evaluation period, with two major outbreaks of rust of variable intensity. Host growth was fitted by a Fourier curve with two significant harmonics. The first and second harmonics accounted for 37·5 and 22·1% of total host growth measured, respectively. A highly significant negative linear correlation was observed between the first harmonic and daily maximum and minimum temperatures, rainfall, and duration of the light period. Inoculum availability was not a limiting factor for disease progress since urediniospores were present during most of the period studied. A major peak in numbers of rust spores followed the main peak of disease severity. Thus, rust epidemics on rose apple in central Brazil were shown to depend on the duration of leaf wetness in the dark, and also on night-time temperatures during that same wetness period. This study is the first example of a periodical analysis of an epidemic in a perennial crop. 相似文献
10.