全文获取类型
收费全文 | 189篇 |
免费 | 14篇 |
国内免费 | 1篇 |
专业分类
林业 | 22篇 |
农学 | 13篇 |
基础科学 | 1篇 |
43篇 | |
综合类 | 16篇 |
农作物 | 16篇 |
水产渔业 | 26篇 |
畜牧兽医 | 43篇 |
园艺 | 11篇 |
植物保护 | 13篇 |
出版年
2024年 | 1篇 |
2023年 | 2篇 |
2022年 | 11篇 |
2021年 | 9篇 |
2020年 | 7篇 |
2019年 | 11篇 |
2018年 | 17篇 |
2017年 | 8篇 |
2016年 | 7篇 |
2015年 | 5篇 |
2014年 | 8篇 |
2013年 | 16篇 |
2012年 | 14篇 |
2011年 | 17篇 |
2010年 | 14篇 |
2009年 | 6篇 |
2008年 | 8篇 |
2007年 | 4篇 |
2006年 | 5篇 |
2005年 | 6篇 |
2004年 | 4篇 |
2003年 | 4篇 |
2002年 | 4篇 |
2000年 | 2篇 |
1997年 | 2篇 |
1996年 | 1篇 |
1990年 | 1篇 |
1989年 | 1篇 |
1988年 | 1篇 |
1986年 | 2篇 |
1985年 | 2篇 |
1984年 | 1篇 |
1967年 | 1篇 |
1966年 | 1篇 |
1945年 | 1篇 |
排序方式: 共有204条查询结果,搜索用时 15 毫秒
21.
Foot-and-mouth disease (FMD) is a highly contagious disease of cloven-hoofed animals including cattle, pigs, sheep and many wildlife species. It can cause enormous economic losses when incursions occur into countries which are normally disease free. In addition, it has long-term effects within countries where the disease is endemic due to reduced animal productivity and the restrictions on international trade in animal products. The disease is caused by infection with foot-and-mouth disease virus (FMDV), a picornavirus. Seven different serotypes (and numerous variants) of FMDV have been identified. Some serotypes have a restricted geographical distribution, e.g. Asia-1, whereas others, notably serotype O, occur in many different regions. There is no cross-protection between serotypes and sometimes protection conferred by vaccines even of the same serotype can be limited. Thus it is important to characterize the viruses that are circulating if vaccination is being used for disease control. This review describes current methods for the detection and characterization of FMDVs. Sequence information is increasingly being used for identifying the source of outbreaks. In addition such information can be used to understand antigenic change within virus strains. The challenges and opportunities for improving the control of the disease within endemic settings, with a focus on Eurasia, are discussed, including the role of the FAO/EuFMD/OIE Progressive Control Pathway. Better control of the disease in endemic areas reduces the risk of incursions into disease-free regions. 相似文献
22.
23.
Baktiar O Karim Syed Z Ali Jennifer A Landolfi Jill F Mann Guosheng Liu Archie Christian John F Dicello Dorothy L Rosenthal David L Huso 《Veterinary clinical pathology / American Society for Veterinary Clinical Pathology》2008,37(2):229-236
BACKGROUND: Fine needle aspiration (FNA) offers a rapid and minimally invasive means to distinguish malignant from benign neoplasms. However, few studies have been published regarding the cytopathology of mammary tumors in rats despite widespread use of the rat model for breast cancer formation and inhibition. OBJECTIVE: The purpose of this study was to determine the diagnostic accuracy of FNA cytology and to develop distinguishing cytologic criteria for the diagnosis of radiation-induced benign and malignant mammary tumors in rats. METHODS: In a study of radiation-induced mammary carcinogenesis, 100 Sprague-Dawley rats with cutaneous masses were randomly chosen for FNA. The aspirates were smeared, fixed, and stained with a modified Papanicolaou procedure for diagnostic evaluation. Cytologic and histologic diagnoses (benign vs malignant) were compared, and diagnostic accuracy was calculated using the histologic diagnosis as the criterion standard. FNA smears were scored semiquantitatively on a scale of 1-4 for cellularity, atypia, nuclear size, chromatin pattern, nuclear membrane thickness, nucleoli, and mitoses. The background was evaluated for necrosis, hemorrhage, inflammation, and mucosecretory material. Cytomorphologic features were compared statistically between benign and malignant tumors, based on the histologic diagnosis. RESULTS: The sensitivity of FNA was 92.3% and specificity was 89.4% for the detection of malignancy. However, 14% of specimens, all fibroadenomas by histology, had insufficient cells for cytologic evaluation, for an overall accuracy rate of 78.0%. Malignant tumors had significantly higher scores for all cytomorphologic features, and were significantly more likely to contain cell clusters and necrotic debris. CONCLUSIONS: FNA is an accurate method for differentiating benign and malignant rat mammary tumors. 相似文献
24.
ABSTRACTTraditionally, farmers determine when a crop is ready for harvest by observing sensible attributes. They inspect the color or other physical observables which their crops exhibit and make decisions based on these observations and their past experience. This research presents for the first time a mathematical method employing Fourier-transform infrared spectroscopy to quantify the maturation or ripeness of Cameo apple based on the changes in concentrations of selected constituent components (e.g., glucose) in the apple fruit. Cameo apple fruit samples were collected from a single tree every 15 days during the last 60 days of the apple fruit maturation cycle and then analyzed with Fourier-transform infrared spectroscopy. The vibrational bands from the Fourier-transform infrared spectra were assigned to specific functional group. The peak intensities of the vibrational bands corresponding to glucose molecule were normalized and plotted against the number of days remaining before the apple fruit maturity and were observed to show a linear relationship. This relationship can be used to calculate the time required for the apple fruit to reach maturity and also to calculate the concentration of constituent components at any stage of its growth cycle. 相似文献
25.
A. Karami A. Christianus Z. Ishak S. C. Courtenay M. A. Syed M. Noor Azlina H. Noorshinah 《Aquaculture International》2010,18(5):851-858
Triploid African catfish (Clarias gariepinus) produced through cold shock 3 min post fertilization were compared to diploid offspring of the same parentage at 66 days
of age. Triploid fish were significantly shorter (11%) and weighed less (18%) than diploids but showed no significant difference
in mortality or cannibalism, which can be an important source of losses under aquaculture conditions. Erythrocytes of triploid
fish were more oval shaped than the normal spherical shape of diploid erythrocytes, were significantly larger (38%) and had
nuclei that were significantly larger (25%) than observed in diploid fish. Erythrocyte morphological characteristics show
potential as an indicator for the detection of triploidy in African catfish. 相似文献
26.
Azam Ali Vijay Baheti Jiri Militky Zaman Khan Syed Qummer Zia Gilani 《Fibers and Polymers》2018,19(3):607-619
The present work described the development of multifunctional, electrically conductive and durable fabrics by coating of silver and copper particles using a dipping-drying method. The particles were directly grown on fabric structure to form electrically conductive fibers. Particles were found to fill the spaces between the microfibers, and were stacked together to form networks with high electrical conductivity. The electrically conductive fabrics showed low resistance with high stretch ability. The utility of conductive fabrics was analyzed for electromagnetic shielding ability over frequency range of 30 MHz to 1.5 GHz. The EMI shielding was found to increase with increase in concentration of copper and silver particles. Furthermore, the heating performance of the copper and silver coated fabric was studied through measuring the change in temperature at the surface of the fabric while applying a voltage difference across the fabric. The maximum temperature (119°C for silver and 112°C for copper) were obtained when the applied voltage was 10 V. Moreover, the role of deposited particles on antibacterial properties was examined against pathogenic bacteria such as Staphylococcus aureus and Escherichia coli. At the end, the durability of coated fabrics was examined against several washing cycles. The fabrics showed good retention of the particles, proved by small loss in the conductivity of the material after washing. 相似文献
27.
28.
29.
Iqra Javid Mahroze Fatima Syed Zakir Hussain Shah Muhammad Afzal 《Aquaculture Nutrition》2021,27(1):217-224
The effect of organic acids (OA) and dicalcium phosphate (Pi) supplementation in the feed of Labeo rohita fingerlings was studied by formulating seven practical diets, designed as D1 with no feed additives {dicalcium phosphorus (Pi) and organic acid (OA) blend} while, D2, D3, D4 and D5 were supplemented with Pi at the graded levels of 5, 10, 15 and 20 g/kg, respectively, whereas D6 and D7 contained blend of OA at 15 and 30 g/kg, respectively. The diet supplemented with OA blend exhibited increase (p < .05) in growth of L. rohita fingerlings compared with the diet supplemented with Pi. The OA supplementation at both levels showed significant improvement in nutrients digestibility and minerals absorption in fingerlings. Moreover, in case of muscle proximate composition, crude fat (CF) and crude protein (CP) were increased (p < .05) with the inclusion of OA blend in the diet while crude ash (CA) was improved by Pi supplementation. Additionally, digestive enzyme activities were not affected (p ? .05) by OA blend supplementation while increased activities were observed in the fingerlings fed with Pi diet. Consequently, supplementation of OA blend in the diet improved the growth performance and nutrient status while Pi enhanced digestive enzyme activities of L. rohita fingerlings. 相似文献
30.
Gyula Vida Mariann Gál Andrea Uhrin Ottó Veisz Naeem Hasan Syed Andrew J. Flavell Zhulin Wang Zoltán Bedő 《Euphytica》2009,170(1-2):67-76
The resistance genes Lr9, Lr24, Lr25, Lr29, Lr35 and Lr37, which were not previously utilised in Hungary, have been incorporated into four Martonvásár winter wheat cultivars using marker-assisted selection with PCR-based markers. In the course of a backcross programme, the genes were transferred into Martonvásár wheat varieties and various BC generations were produced. Work aimed at pyramiding resistance genes is currently underway in Martonvásár, and plants containing the gene combinations Lr9 + Lr24, Lr9 + Lr25 and Lr9 + Lr29 are now available. From the BC2F4 generation of the ‘Mv Emma’*3/’R.L.6010’ combination (‘R.L.6010’ is the donor of the Lr9 gene) 287 lines were tested for leaf rust resistance in an artificially inoculated nursery. A co-dominant primer combination was designed to identify both resistant and susceptible offsprings. The results of resistance tests and molecular marker detection agreed in most cases. Designated leaf rust resistance genes were identified with molecular markers in wheat varieties and breeding lines. The Lr26 and Lr34 resistance genes occur frequently in the Martonvásár gene pool, and the presence of the Lr37 gene has also been detected in a number of Hungarian genotypes. 相似文献