全文获取类型
收费全文 | 4071篇 |
免费 | 208篇 |
国内免费 | 2篇 |
专业分类
林业 | 286篇 |
农学 | 151篇 |
基础科学 | 14篇 |
1074篇 | |
综合类 | 197篇 |
农作物 | 324篇 |
水产渔业 | 450篇 |
畜牧兽医 | 1389篇 |
园艺 | 85篇 |
植物保护 | 311篇 |
出版年
2023年 | 39篇 |
2022年 | 78篇 |
2021年 | 173篇 |
2020年 | 164篇 |
2019年 | 206篇 |
2018年 | 163篇 |
2017年 | 173篇 |
2016年 | 159篇 |
2015年 | 124篇 |
2014年 | 187篇 |
2013年 | 272篇 |
2012年 | 334篇 |
2011年 | 320篇 |
2010年 | 187篇 |
2009年 | 168篇 |
2008年 | 271篇 |
2007年 | 286篇 |
2006年 | 187篇 |
2005年 | 158篇 |
2004年 | 137篇 |
2003年 | 132篇 |
2002年 | 133篇 |
2001年 | 20篇 |
2000年 | 19篇 |
1999年 | 19篇 |
1998年 | 14篇 |
1997年 | 13篇 |
1996年 | 10篇 |
1995年 | 10篇 |
1994年 | 11篇 |
1993年 | 9篇 |
1992年 | 6篇 |
1991年 | 4篇 |
1990年 | 10篇 |
1989年 | 11篇 |
1988年 | 7篇 |
1987年 | 8篇 |
1986年 | 6篇 |
1985年 | 6篇 |
1984年 | 10篇 |
1983年 | 4篇 |
1982年 | 3篇 |
1980年 | 3篇 |
1977年 | 3篇 |
1975年 | 2篇 |
1973年 | 3篇 |
1972年 | 2篇 |
1969年 | 3篇 |
1966年 | 4篇 |
1955年 | 2篇 |
排序方式: 共有4281条查询结果,搜索用时 15 毫秒
31.
Goddeeris BM 《Veterinary immunology and immunopathology》2002,87(3-4):391-394
A few reflections are made on the future strategies and approaches for combating infectious diseases of livestock, keeping into consideration public concern on food quality and availability. The policy of eradication of pathogens/diseases instead of vaccination has rendered livestock naive to certain pathogens and as a consequence susceptible to epidemic outbreaks, even more so as we have to conclude that outside attack is quite often difficult to control. Therefore, immunoprophylactic measures in livestock remain top priority and will in the future focus more on the induction of mucosal immunity and the activation of innate immunity. 相似文献
32.
OBJECTIVE: To evaluate use of a pasteurized tumoral autograft prepared from the resected primary bone neoplasm for limb sparing in a dog with distal radial osteosarcoma (OSA). STUDY DESIGN: Clinical case report. ANIMALS: A 9-year-old male Maremma shepherd dog. METHODS: After right distal radial OSA removal, the tumoral autograft was pasteurized. The excised bone segment was placed in a sterile watertight box containing sterile saline solution preheated to 65 degrees C in a water bath. The box was kept immersed in the water bath at 65 degrees C for 40 minutes to kill the tumor cells. The autograft was then fixed in the host with a plate and screws based on standard AO/ASIF technique for carpal arthrodesis. Three doses of cisplatin (70 mg/m(2) intravenously) were administered, 3 weeks apart; the initial dose was administered the day after surgery. RESULTS: The autograft was incorporated in a manner comparable to an allograft, and after 708 days, the metallic implants were removed. A 1-month activity restriction as well as spoon splint to protect the leg from a full loading were used thereafter. Limb function was fair to good, and the dog remains disease free after 56 months. CONCLUSIONS: A pasteurized autograft consisting of the resected primary bone neoplasm is a valid alternative to a cortical bone allograft for limb sparing in dogs with appendicular OSA in terms of feasibility and pattern of healing. CLINICAL RELEVANCE: This procedure can be an alternative method of limb sparing when difficulties are encountered in establishing and maintaining a canine bone allograft bank. 相似文献
33.
Raquel Sartor Maria J Mamprim Regina F Takahira Mariana F de Almeida 《Acta veterinaria Scandinavica》2010,52(1):36
Background
Doppler ultrasonography is an important tool for evaluating hepatic portal hemodynamics. However, no study in dogs of different body weights, in the range encountered in routine clinical veterinary practice, has been reported. It can be difficult to obtain an ideal insonation angle when evaluating the main portal vein, so evaluation of the right portal vein branch has been described in humans as an alternative. The aim of this study was to analyze, through Doppler ultrasonography, the hemodynamics in the right portal vein branch in dogs of different body weights.Methods
Thirty normal dogs were divided in three groups by weight, in order to establish normal values for mean velocity, flow volume and portal congestion index of the right portal vein branch by means of Doppler ultrasonography.Results
In all dogs ideal insonation angles were obtained for the right portal vein branch. The average velocity was similar in the three groups, but the portal congestion index and the flow volume differed, showing that the weight of the dog can influence these values.Conclusion
Doppler ultrasonography for the evaluation of flow in the right branch of the portal vein could be a viable alternative, or complement, to examining the main vessel segment. This is especially so in those animals in which an ideal insonation angle for examination of the main portal vein is hard to obtain. In addition, the weight of the dog must be considered for the correct evaluation of the portal system hemodynamics, particularly for portal blood flow and the congestion index. 相似文献34.
G. Fernandes de Queiroz M. Lúcia Zaidan Dagli S. Aparecida Meira J. Maria Matera 《Veterinary and comparative oncology》2013,11(3):230-235
This work aimed to evaluate serum vascular endothelial growth factor (VEGF) in 25 dogs with soft tissue sarcoma, and in 30 healthy dogs. Blood was collected once time from the control animals and three times, in the same way, from animals with sarcoma. Blood count was performed in the blood collected, and serum VEGF was measured by enzyme‐linked immunosorbent assay quantitative method. Serum VEGF in control animals was similar to patients with soft tissue sarcoma. There was a reduction in serum VEGF after the sarcoma resection. There was positive correlation between serum VEGF and neutrophil counts, and negative between VEGF and hemoglobin content in animals with sarcoma. Animals with hemangiopericytoma showed higher serum VEGF levels compared to the patients with malignant peripheral nerve sheath. Circulating blood cells can contribute to elevate VEGF serum concentrations in dogs with soft tissue sarcomas and a possible role of VEGF in the angiogenesis of these tumors. 相似文献
35.
36.
Zannoni A Giunti M Bernardini C Gentilini F Zaniboni A Bacci ML Forni M 《Research in veterinary science》2012,93(2):921-927
Procalcitonin (PCT), recognised as a marker of sepsis, was investigated in a porcine model of endotoxic shock. The results showed that continuous IV infusion (1-4 h) of LPS (40 μg/kg) in pigs was able to induce a generalised increase of PCT expression in lung, heart, kidney and liver. The increase in PCT was significant only in kidney and was accompanied by an increase in IL-6 gene expression. In vitro results demonstrated that peripheral blood mononuclear cells (PBMCs), as well as endothelial cells, were potentially capable of contributing to in vivo extrathyroidal PCT production. These findings support previous data from pigs concerning the occurrence of widespread activation of PCT extrathyroidal gene expression during endotoxic shock in pigs. Nevertheless, the levels of PCT detected were very low, suggesting the need for additional studies to validate the pig as a reliable animal model for investigating the role of PCT in sepsis. 相似文献
37.
Jessica Maria Leite dos Santos Jomar Patrício Monteiro Wesley Lyeverton Correia Ribeiro Iara Tersia Freitas Macedo Ana Lourdes Fernandes Camurça-Vasconcelos Luiz da Silva Vieira Claudia Maria Leal Bevilaqua 《Veterinary parasitology》2014,199(3-4):160-164
Haemonchus contortus is the most prevalent nematode in Brazil. The objective of this study was to select 6 populations of H. contortus of known or suspected benzimidazole resistance status and characterize these using quantitative real-time polymerase chain reaction (qPCR) for single nucleotide polymorphisms (SNPs) F200Y, F167Y and E198A in the β-tubulin isotype 1 gene. qPCR was performed using DNA from a pool of 10 adult male H. contortus from a single animal per farm. Faecal egg count reduction test (FECRT) and egg hatch test (EHT) were used to determine the resistance status. Samples were obtained from 6 farms located in 5 counties in the Ceará State: Tauá, Boa Viagem, Quixadá, Santa Quitéria and Solonópole. The inbred-susceptible-Edinburgh (ISE) isolate was used as reference for comparative purposes in the qPCR. Benzimidazole resistance was detected by FECRT on all farms with efficacy values ranging from 0 to 51%. EC50 values as determined by EHT were all above 1.49 μg/ml. High frequencies of the resistant SNPs F200Y and F167Y alleles were detected but no resistance was detected at SNP E198A. Our results suggest that the SNPs F167Y and F200Y are both important for benzimidazole resistance in the studied populations. 相似文献
38.
Hartwell Birgitte Wiedemann Iñiguez Luis Mueller Joaquin Wurzinger Maria Knaus W. F. 《Tropical animal health and production》2010,42(7):1573-1578
Intensive lamb fattening systems are evolving in developing Middle Eastern countries due to high demand for lambs at favorable
prices; however, little is known about their characteristics and constraints. A survey was conducted in Syria involving 241
farmers to characterize the fattening production systems and main constraints, with emphasis on feeding, management, labor,
and marketing. Most farmers (90%) considered the income from fattening to be from medium to high, and 57% expressed that lamb
fattening along with alternative income sources compose the family's livelihood strategies. Fattening systems offer employment
to family members. Market price was the main decision factor to buy and sell lambs, but this was only part of various marketing
aspects. Male lambs usually bought at markets at the mean age of 4 months (mean weight of 31 kg) are sold after fattening
at a 50–60 kg weight range. The average yearly fattening cycle was 2.7 batches, and the average number of lambs per batch
was 232. For 65% (n = 241) of the farmers the major constraint to fattening was feeding cost, and for about a half of farmers (51%, n = 241), disease outbreaks and prices for veterinarian services constituted the second important constraint. Research on least-cost
fattening diets and curbing disease problems to increase farmer's income margins is needed. It is expected that due to existing
commonalities, the information emerging from this study regarding major constraints to Awassi lamb fattening systems could
be useful for an across-synthesis on Awassi fattening production in the region. 相似文献
39.
Lester J. Pérez Heidy Díaz de Arce Maria I. Percedo Patricia Domínguez Maria T. Frías 《Research in veterinary science》2010,88(3):528-530
To obtain information about the porcine circovirus type 2 (PCV2) infection status of pigs in Cuba and the probable association of PCV2 with other porcine viruses, tissue samples collected from ill pigs were evaluated using polymerase chain reaction (PCR). The PCR analysis showed that 67.7% of the samples (23/34) from seven swine herds of six different geographic regions were detected to be positive for PCV2. Ten of the 23 PCV2 positive samples (43.5%) shown a concurrent infection with porcine parvovirus (PPV) and 17 of 23 PCV2 positive samples (73.9%) exhibited a concomitant infection with classical swine fever virus (CSFV). This study is the first report of PCV2 infecting pigs with different clinical conditions in Cuban swine herds and provides evidence of PCV2 co-infection with PPV and CSFV in the field. 相似文献
40.
The protozoan parasite Neospora caninum is a major cause of abortion in cattle throughout the world. In the process of propagating Neospora in vitro and producing specific antibodies for development of diagnostic assays in the food supply, our laboratory identified the presence of bovine antibodies to N. caninum in fetal bovine sera. The sera were produced commercially and preferentially recommended for tissue culture use and monoclonal antibody production. Seventeen different fetal bovine serum samples of different grades and from four different companies were examined for the presence of total IgG, IgG1, IgG2, and IgM specific for N. caninum. All of the tested serum samples recognized N. caninum specific bands on Western blot. Low IgG serum also recognized these antigens but with lower intensity. Antibody response was also evaluated using a commercially available ELISA kit for N. caninum. 相似文献