全文获取类型
收费全文 | 196523篇 |
免费 | 10779篇 |
国内免费 | 132篇 |
专业分类
林业 | 7367篇 |
农学 | 5819篇 |
基础科学 | 1349篇 |
22844篇 | |
综合类 | 35615篇 |
农作物 | 7250篇 |
水产渔业 | 9527篇 |
畜牧兽医 | 101938篇 |
园艺 | 2371篇 |
植物保护 | 13354篇 |
出版年
2018年 | 2426篇 |
2017年 | 2622篇 |
2016年 | 2520篇 |
2015年 | 2194篇 |
2014年 | 2677篇 |
2013年 | 7310篇 |
2012年 | 5021篇 |
2011年 | 6287篇 |
2010年 | 3977篇 |
2009年 | 4072篇 |
2008年 | 6169篇 |
2007年 | 5815篇 |
2006年 | 5695篇 |
2005年 | 5273篇 |
2004年 | 5111篇 |
2003年 | 5150篇 |
2002年 | 4943篇 |
2001年 | 6134篇 |
2000年 | 5966篇 |
1999年 | 4779篇 |
1998年 | 1928篇 |
1997年 | 2008篇 |
1996年 | 1886篇 |
1995年 | 2307篇 |
1994年 | 2117篇 |
1993年 | 2014篇 |
1992年 | 4235篇 |
1991年 | 4442篇 |
1990年 | 4397篇 |
1989年 | 4399篇 |
1988年 | 4089篇 |
1987年 | 4211篇 |
1986年 | 4342篇 |
1985年 | 4189篇 |
1984年 | 3450篇 |
1983年 | 3053篇 |
1982年 | 2147篇 |
1981年 | 1955篇 |
1979年 | 3169篇 |
1978年 | 2646篇 |
1977年 | 2266篇 |
1976年 | 2092篇 |
1975年 | 2206篇 |
1974年 | 2905篇 |
1973年 | 2930篇 |
1972年 | 2854篇 |
1971年 | 2569篇 |
1970年 | 2433篇 |
1969年 | 2252篇 |
1967年 | 1945篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
Worster AA Lillich JD Cox JH Rush BR 《Journal of the American Veterinary Medical Association》2000,216(11):1795-8, 1760
A 9-year-old pregnant mare was referred for evaluation of a nonhealing wound of 8 weeks' duration on the lateral aspect of the left forelimb. A soft tissue mass encircled the proximal two thirds of the metacarpus; radiography revealed a moderate periosteal reaction affecting metacarpal bone i.v. Histologic and immunohistochemical examinations revealed eosinophilic granulomatous inflammation and Pythium sp in the soft tissues. The mare was treated for 12 days with antimicrobials, medicated wound dressings, debridement, and i.v. administration of sodium iodide; radiography revealed progression of the bone lesions. The mare was treated by regional arterial perfusion with miconazole and excision of affected soft tissues and the distal two thirds of metacarpal bone i.v. The mare recovered without complications and gave birth to a healthy foal. Regional perfusion of antifungal agents provides high concentrations in soft and osseous tissues and permits use of low dosages of agents administered by other routes, which reduces cost, adverse effects, and teratogenic effects. 相似文献
992.
Hill SL Cheney JM Taton-Allen GF Reif JS Bruns C Lappin MR 《Journal of the American Veterinary Medical Association》2000,216(5):687-692
OBJECTIVE: To determine prevalence of enteric zoonotic organisms in cats in north-central Colorado. DESIGN: Prospective study. SAMPLE POPULATION: Serum and fecal samples from 87 cats with diarrhea, 106 cats without diarrhea, and 12 cats for which fecal consistency was unknown. PROCEDURES: Samples were obtained from client-owned cats and cats at a humane society shelter. Serum was assayed for feline leukemia virus antigen and antibodies against feline immunodeficiency virus, IgM antibodies against Toxoplasma gondii, and IgG antibodies against T gondii and Cryptosporidium parvum. Microscopic examination of unstained feces was performed after centrifugation in a zinc sulfate solution, thin fecal smears were stained with acid fast stain and examined for C parvum, and bacteriologic culture of feces was used to detect aerobic and anaerobic bacteria. RESULTS: Enteric zoonotic organisms were detected in feces from 27 of 206 (13.1%) cats and included C parvum (5.4%), Giardia spp (2.4%). Toxocara cati (3.9%), Salmonella enterica serotype Typhimurium (1.0%), and Campylobacter jejuni (1.0%); each organism was detected in samples from cats with and without diarrhea. Although differences between groups were not significant, a higher proportion of shelter cats (18.2%) had enteric zoonotic organisms than client-owned cats (10.1%). CONCLUSIONS AND CLINICAL RELEVANCE: Enteric zoonotic organisms were detected in feces of 13.1% of cats, suggesting that cats, particularly those in homes of immunocompromised humans, should be evaluated for enteric zoonotic organisms. 相似文献
993.
Smith KE Wall R Howard JJ Strong L Marchiondo AA Jeannin P 《Veterinary parasitology》2000,88(3-4):261-268
The insecticidal effects of the phenylpyrazole, fipronil, and a pyrethroid, beta-cyfluthrin, on larvae of the blowfly Lucilia sericata were determined in laboratory assays. When first stage larvae of L. sericata were reared on homogenized pig liver which had been treated with known amounts of test compounds, both fipronil and beta-cyfluthrin induced significant levels of mortality compared to acetone and water controls. However, fipronil was approximately 10 times more toxic than beta-cyfluthrin to L. sericata larvae following ingestion. Beta-cyfluthrin had little effect on mortality until concentrations of approximately 0.5 ppm were reached. In contrast, fipronil effected L. sericata mortality at a concentration of 0.05 ppm and 100% mortality was reached by 0.5 ppm. The lethal concentration (LC50) value for beta-cyfluthrin was 1.56 ppm as compared to 0.14 ppm for fipronil. Following contact of first and third stage larvae with cloth impregnated with known amounts of test compound, the mortality profiles of fipronil and beta-cyfluthrin were similar. At short contact times, the LC50 values for fipronil were lower than those for beta-cyfluthrin. However, at the highest contact time evaluated for the first stage larvae, 300 s, there was a reversal in this trend. The results suggest that the phenylpyrazole fipronil may represent a new potential insecticide for development against blowfly strike of sheep. 相似文献
994.
995.
996.
997.
To describe the clinical features and treatment of a cat that was initially presented with fibrotic myopathy affecting the left tensor fascia lata. Approximately 5 months later, the cat was presented again with multiple idiopathic fibrotic myopathies, affecting the ipsilateral rectus femoris and the contralateral semitendinosus muscles. These were each separate lesions and occurred without known history of trauma. Surgical resection of the fibrotic portion of the affected muscles resulted in immediate, but not long-term, resolution of clinical signs. 相似文献
998.
Marie-Etancelin C Basso B Davail S Gontier K Fernandez X Vitezica ZG Bastianelli D Baéza E Bernadet MD Guy G Brun JM Legarra A 《Journal of animal science》2011,89(3):669-679
Genetic parameters of traits related to hepatic lipid metabolism, carcass composition, and product quality of overfed mule ducks were estimated on both parental lines of this hybrid: the common duck line for the maternal side and the Muscovy line for the paternal side. The originality of the statistical model was to include simultaneously the additive genetic effect of the common ducks and that of the Muscovy ducks, revealing a greater genetic determinism in common than in Muscovy. Plasma metabolic indicators (glucose, triglyceride, and cholesterol contents) were heritable, in particular at the end of the overfeeding period, and heritabilities increased with the overfeeding stage. Carcass composition traits were highly heritable in the common line, with values ranging from 0.15 for liver weight, 0.21 for carcass weight, and 0.25 for abdominal fat weight to 0.32 for breast muscle weight. Heritabilities of technological outputs were greater for the fatty liver (0.19 and 0.08, respectively, on common and Muscovy sides for liver melting rate) than for the pectoralis major muscle (between 0.02 and 0.05 on both parental sides for cooking losses). Fortunately, the processing industry is mainly facing problems in liver quality, such as too high of a melting rate, than in meat quality. The meat quality appraisal criteria (such as texture and cooking losses), usually dependent on pH and the rate of decline of pH, were also very lowly heritable. This study demonstrated that genetic determinism of meat quality and ability of overfeeding is not similar in the common population and in the Muscovy population; traits related to fattening, muscle development, and BW have heritability values from 2 to 4 times greater on the common line than on the Muscovy line, which is relevant for considering different selection strategies. 相似文献
999.
Moré G Abrahamovich P Jurado S Bacigalupe D Marin JC Rambeaud M Venturini L Venturini MC 《Veterinary parasitology》2011,177(1-2):162-165
Sarcocystis cruzi, S. hirsuta and S. hominis are apicomplexan parasites that affect cattle worldwide with variable prevalence. The aim of the present study was to evaluate the prevalence of Sarcocystis spp. in Argentinean cattle comparing microscopic fresh examination and molecular methods. Blood, myocardium and loin samples were collected in five slaughterhouses from a total of 380 bovines. Origin of animals was representative of the major beef cattle production area of Argentina. Samples were analyzed by fresh microscopical examination, transmission electron microscopy (TEM), IFAT and PCR-RFLP. Thin walled sarcocysts corresponding with S. cruzi were found in 99.5% of heart samples. Sarcocysts were detected in 73.1% of loin samples; 71.5% had S. cruzi cysts and 23.1% had thick walled sarcocysts (S. hirsuta or S. hominis). TEM observation revealed the presence of characteristic S. hominis and S. hirsuta cyst walls in 7 and 1 loin samples respectively. Using IFAT, 379/380 animals had titers 25 or higher, showing a full agreement with fresh examination. Amplification products were detected in 35.5% (135/380) of loin samples; however Sarcocystis species could only be determined by RFLP in 29 samples. Agreement between fresh examination and PCR was low (Kappa value=0.262). This is the first report of S. hominis and S. hirsuta in Argentina. Further studies are needed to improve the sensitivity of molecular methods for species identification, especially for differentiation of S. cruzi and S. hirsuta from the zoonotic species S. hominis. The results of the present study and others focusing on sensitivity and specificity of Sarcocystis spp. diagnostic methods should contribute to improve food safety. 相似文献
1000.
Mendes MC Lima CK Nogueira AH Yoshihara E Chiebao DP Gabriel FH Ueno TE Namindome A Klafke GM 《Veterinary parasitology》2011,180(3-4):383-388
This study was undertaken to determine the flea diversity on urban dogs and cats in Australia in 2009-2010. A total of 2530 fleas were recovered from 291 animals (151 dogs, 69 cats and 71 uncategorised dogs or cats) from veterinary clinics across five states of Australia. The majority of specimens were from coastal areas. The cat flea (Ctenocephalides felis felis) was the most frequent flea species identified (98.8%, 2500/2530). The only other flea species identified was the stickfast flea (Echidnophaga gallinacea) from Western Australia. Sequencing of the cytochrome oxidase subunit II mtDNA revealed a single haplotype across Australia within a subset of C. f. felis (n=19). Our study demonstrated dominance and haplotype homogeneity of C. f. felis on dogs and cats. Although Ctenocephalides canis was recovered from a feral fox, it was not identified from the sample of fleas analysed. This suggests that, under current conditions, it is unlikely that foxes are reservoirs of C. canis for domestic dogs or cats residing in coastal Australia, as previously speculated. 相似文献