全文获取类型
收费全文 | 2569篇 |
免费 | 136篇 |
国内免费 | 3篇 |
专业分类
林业 | 133篇 |
农学 | 153篇 |
基础科学 | 7篇 |
476篇 | |
综合类 | 170篇 |
农作物 | 326篇 |
水产渔业 | 228篇 |
畜牧兽医 | 1011篇 |
园艺 | 41篇 |
植物保护 | 163篇 |
出版年
2023年 | 17篇 |
2022年 | 47篇 |
2021年 | 67篇 |
2020年 | 48篇 |
2019年 | 62篇 |
2018年 | 73篇 |
2017年 | 83篇 |
2016年 | 85篇 |
2015年 | 91篇 |
2014年 | 124篇 |
2013年 | 140篇 |
2012年 | 197篇 |
2011年 | 209篇 |
2010年 | 122篇 |
2009年 | 135篇 |
2008年 | 167篇 |
2007年 | 161篇 |
2006年 | 179篇 |
2005年 | 99篇 |
2004年 | 104篇 |
2003年 | 97篇 |
2002年 | 93篇 |
2001年 | 68篇 |
2000年 | 42篇 |
1999年 | 31篇 |
1998年 | 14篇 |
1997年 | 5篇 |
1996年 | 3篇 |
1995年 | 8篇 |
1994年 | 5篇 |
1993年 | 5篇 |
1992年 | 11篇 |
1991年 | 4篇 |
1990年 | 14篇 |
1989年 | 14篇 |
1988年 | 7篇 |
1987年 | 4篇 |
1985年 | 6篇 |
1981年 | 3篇 |
1978年 | 3篇 |
1976年 | 2篇 |
1975年 | 4篇 |
1974年 | 7篇 |
1973年 | 10篇 |
1971年 | 3篇 |
1970年 | 2篇 |
1968年 | 3篇 |
1966年 | 4篇 |
1949年 | 2篇 |
1929年 | 2篇 |
排序方式: 共有2708条查询结果,搜索用时 0 毫秒
21.
An 8-year-old Shih-tzu dog was presented with a 2-week history of cough and nasal discharge. Upon presentation, the dog had constant open-mouth breathing with stertor and blood-tinged mucopurulent nasal discharge. Oral examination revealed a missing right mandibular second premolar tooth and severe periodontal disease. Computed tomography showed a radiodense, retropharyngeal foreign body. The foreign body was removed using caudal rhinoscopy. The foreign body was the right mandibular second premolar covered by thick calculus. 相似文献
22.
23.
A biological attack on livestock or poultry could result in the loss of valuable animals, costs related to the containment of outbreaks and the disposal of carcasses, lost trade and other economic effects involving suppliers, transporters, distributors and restaurants; however, it is not possible to secure all livestock, and livestock are much less well guarded than human targets. Thus, the vulnerability of the livestock industry to the introduction of biological agents varies for the following reasons: (i) the majority of lethal and contagious biological agents are environmentally resilient, endemic in foreign countries and harmless to humans, making it easier for terrorists to acquire, handle and deploy these pathogens, (ii) with animals concentrated in fewer production facilities and frequently transported between these facilities, a single pathogen introduction could cause widespread infection and (iii) the extent of human travel around the globe makes it difficult to exclude exotic animal diseases as possible biological agents. Historically, many governments have developed and planned to use biological agents for direct attacks on livestock or poultry. In the past, developed nations have actively developed biological weapons to target animals. The potential spectrum of bioterrorism ranges from isolated acts against individuals by individuals to tactical and strategic military attacks and state‐sponsored international terrorism intended to cause mass casualties in animals, humans or both. This review provides an overview of the past development and use of biological weapons and describes potential future attacks. 相似文献
24.
TS Kim SH Lee GT Gang YS Lee SU Kim DB Koo MY Shin CK Park DS Lee 《Reproduction in domestic animals》2010,45(5):e201-e206
The sperm‐mediated gene transfer method is applicable to transgenesis in many species that use spermatozoa for reproduction recently, which has been shown various results. In the current study, we show that transgenic porcine embryos can be efficiently produced by employing a simple transfection method that uses magnetic nanoparticles (MNPs). The complexes formed between plasmid DNA and MNPs were bounded on ejaculated boar spermatozoa at a higher efficiency compared to methods using DNA alone or lipofection. Using confocal microscopy, rhodamine fluorophore‐labelled MNPs were detected on external surfaces of the spermatozoa membrane, which were bounded on zona pellucida of in vitro maturated oocyte during in vitro fertilization. Electron microscopy revealed that clusters of MNPs were detected in inside of plasma membrane and nucleus of the spermatozoa head. Additionally, we found that magnetofected boar spermatozoa could be fertilized with oocytes in vitro and that the resulting gene of green fluorescent protein was detected in fertilized eggs by genomic PCR analysis. Taken together, these results suggest that MNPs can be used to efficiently introduce a transgene into embryo via spermatozoa. 相似文献
25.
Park M 《Journal of the American Veterinary Medical Association》2007,231(2):196-7; author reply 197-8
26.
Effects of road transportation on metabolic and immunological responses in Holstein heifers 下载免费PDF全文
Hyeok‐Joong Kang In Kyu Lee Min‐Yu Piao Chae‐Won Kwak Min Jeong Gu Cheol Heui Yun Hyun‐Jin Kim Hyeon‐Ju Ahn Hee‐Bal Kim Gyeom‐Heon Kim Soo‐Ki Kim Jong‐Youl Ko Jong K. Ha Myunggi Baik 《Animal Science Journal》2017,88(1):140-148
This study examined the effects of road transportation on metabolic and immunological responses in dairy heifers. Twenty Holstein heifers in early pregnancy were divided into non‐transported (NT; n = 7) and transported (T; n = 13) groups. Blood was collected before transportation (BT), immediately after transportation for 100 km (T1) and 200 km (T2), and 24 h after transportation (AT). The T heifers had higher (P < 0.05) blood cortisol and non‐esterified fatty acid concentrations after T1 and T2 than did NT heifers. By contrast, the T heifers had lower (P < 0.05) serum triglyceride concentrations after T1 and T2 than had the NT heifers. The serum cortisol and triglyceride concentrations returned (P > 0.05) to the BT concentrations at 24 h AT in the T heifers. The granulocyte‐to‐lymphocyte ratio and the percentage of monocytes were higher (P < 0.05) after T2 in the T heifers than in the NT heifers, suggesting that transportation stress increased the numbers of innate immune cells. T heifers had higher (P < 0.01) plasma haptoglobin concentrations than NT heifers 24 h AT. In conclusion, transportation increased cortisol secretion and was correlated with increased metabolic responses and up‐regulation of peripheral innate immune cells in dairy heifers. 相似文献
27.
Eun-Ju Kim Sang-Hee Park Young-Sill Choi Soo-Kyoung Shim Mi-Yeoun Park Man Suck Park Kyu-Jam Hwang 《Journal of veterinary science (Suw?n-si, Korea)》2008,9(3):309-315
We investigated the immune response induced by the Francisella (F.) tularensis live vaccine strain (LVS) and the Pohang isolate. After the Balb/c mice were infected intradermally (i.d) with 2 × 104 cfu of F. tularensis LVS and Pohang, respectively, their blood and organs were collected at different times; 0, 3, 6, 24, 72, 96, 120 and 168 h after infection. Using these samples, RT-PCR and ELISA analysis were carried out for the comparative study of the cytokines, including TNF-α, INF-γ, IL-2, IL-4, IL-10 and IL-12. In the Pohang-infected mice at 120 h, the liver showed a 53 times higher level of TNF-α and a 42 times higher level of IFN-γ than the respective levels at the early time points after infection. The levels of TNF-α and IFN-γ induced by LVS were 5 times lower than those induced by the Pohang isolate. Also, the organs from the Pohang-infected mice showed higher levels of TNF-α, IFN-γ, IL-10 and IL-12 than the levels in the LVS-infected mice. The blood from the Pohang-infected mice at 120 h revealed about a 40 times increased level of IFN-γ, and IL-10 was also increased by 4 times at 96 h compared to an early infection time point, while IL-4 was not induced during the whole infection period. These results suggest that F. tularensis may induce a Th1-mediated immune response to in vivo infection and the Pohang isolate has a higher capacity than the LVS to induce an acute immune response in Blab/c mice. 相似文献
28.
Kim YJ Park SI Park SJ Kim HH Jung YW Kwon JT Jang BG Kim HK Cho KO 《The Journal of veterinary medical science / the Japanese Society of Veterinary Science》2008,70(1):17-23
Since the status of endogenous avian leucosis/sarcoma virus (ALSV) infections in Korean broiler chickens is unclear, this study examined embryonated eggs obtained from broiler farms and Korean native chicken breeds in Korea using PCR with the primer sets specific for endogenous ALSVs. The PCR assays detected the genomes of EAV, ev, ev/J and ART-CH belonging to the endogenous ALSV from all embryos tested. Phylogenetically, the Korean EAV genomes were more closely related to the prototype EAV-0 than to the other prototype, E51. The Korean ART-CH elements clustered together but were distinct from the prototype ART-CH clones, 5 and 14. Although there was comparatively little divergence in the nucleotide and amino acid sequences of the Korean ev and ev/J genomes compared with the other known ev and ev/J genomes, the Korean genomes had phylogenetically distinct branches. From these results, endogenous genomes are quite prevalent in Korean broiler chickens. In addition, the endogenous genomes circulating in Korean broiler chickens are genetically different from the other known endogenous genomes. These results are expected to provide useful information for the control and establishment of a surveillance system for endogenous ALSVs in Korea. 相似文献
29.
30.
Sepsis is associated with substantial morbidity and mortality in dogs. Alterations in hemostasis by systemic inflammation play an important role in the pathophysiology of sepsis. To evaluate the functional hemostatic changes in sepsis, we evaluated coagulation profiles and flow cytometric measurement of P-selectin (CD62P) expression on platelets, as well as platelet-leukocyte aggregation from a lipopolysaccharide (LPS)-induced endotoxemia model in dogs (n = 7). A sublethal dose of LPS [1 mg/kg body weight (BW)] induced thrombocytopenia and increased activated partial thromboplastin time (aPTT), prothrombin time (PT), and D-dimer concentrations. Flow cytometry analysis showed a significant increase in P-selectin expression on platelets between 1 and 24 h of a total 48 h of the experiment. In addition, platelet-leukocyte aggregation was significantly increased in the early stage of endotoxemia (at 1 and < 6 h for platelet-monocyte aggregation and at 3 h for platelet-neutrophil aggregation). Our results suggest that CD62P expression on platelets and platelet-leukocyte aggregation, as measured by flow cytometry, can be useful biomarkers of disseminated intravascular coagulation (DIC) in canine sepsis. These functional changes contribute to our understanding of the pathophysiology of hemostasis in endotoxemia. 相似文献