全文获取类型
收费全文 | 3243篇 |
免费 | 184篇 |
专业分类
林业 | 110篇 |
农学 | 82篇 |
基础科学 | 15篇 |
415篇 | |
综合类 | 561篇 |
农作物 | 126篇 |
水产渔业 | 202篇 |
畜牧兽医 | 1622篇 |
园艺 | 81篇 |
植物保护 | 213篇 |
出版年
2022年 | 27篇 |
2021年 | 32篇 |
2020年 | 41篇 |
2019年 | 52篇 |
2018年 | 45篇 |
2017年 | 48篇 |
2016年 | 52篇 |
2015年 | 38篇 |
2014年 | 76篇 |
2013年 | 144篇 |
2012年 | 126篇 |
2011年 | 137篇 |
2010年 | 76篇 |
2009年 | 73篇 |
2008年 | 131篇 |
2007年 | 137篇 |
2006年 | 148篇 |
2005年 | 130篇 |
2004年 | 130篇 |
2003年 | 126篇 |
2002年 | 120篇 |
2001年 | 78篇 |
2000年 | 84篇 |
1999年 | 66篇 |
1998年 | 31篇 |
1997年 | 28篇 |
1996年 | 34篇 |
1995年 | 23篇 |
1993年 | 26篇 |
1992年 | 43篇 |
1991年 | 66篇 |
1990年 | 54篇 |
1989年 | 55篇 |
1988年 | 48篇 |
1987年 | 39篇 |
1986年 | 65篇 |
1985年 | 56篇 |
1984年 | 39篇 |
1983年 | 35篇 |
1981年 | 24篇 |
1980年 | 34篇 |
1979年 | 37篇 |
1978年 | 34篇 |
1976年 | 26篇 |
1974年 | 35篇 |
1973年 | 29篇 |
1972年 | 38篇 |
1971年 | 37篇 |
1970年 | 32篇 |
1967年 | 24篇 |
排序方式: 共有3427条查询结果,搜索用时 15 毫秒
121.
122.
123.
124.
125.
Neoplasms of the perianal gland are common in the dog, particularly the male. Adenomas of the gland develop about 4.5 times more often than do carcinomas of the gland. The adenoma is hormone dependent; thus, castration without excision of the tumor has been successful in promoting regression without recurrence. Microscopic examination of the testes from dogs with perianal gland neoplasms has revealed 1 in 10 with tubular atrophy and 1 in 3 with testicular neoplasia. Interstitial cell tumors have been seen more often than other cell types of testis tumors. 相似文献
126.
127.
Malone FE Wilson EC Pollock JM Skuce RA 《Journal of veterinary medicine. B, Infectious diseases and veterinary public health》2003,50(10):500-504
Tuberculosis, associated with Mycobacterium bovis infection, occurs infrequently in sheep. A sheep flock, which was potentially exposed to a high level of infection from in-contact tuberculous cattle, was examined for evidence of infection. Six sheep that had given a positive reaction to the comparative intradermal tuberculin test were examined post mortem. Tuberculous lesions were present in four of these sheep. Lesion morphology and distribution in the sheep was similar to that in cattle. M. bovis was cultured from the lesions and the isolates were strain typed by spoligotyping and variable number of tandem repeats (VNTR) typing. Tuberculin-reacting sheep also reacted positively to an assay for in vitro release of interferon-gamma. This paper describes the first report of an outbreak of tuberculosis in sheep in either Britain or Ireland. The report describes immunology and pathology findings and, using molecular typing techniques, suggests that the sheep had been infected from in-contact cattle. 相似文献
128.
Delahay RJ Wilson GJ Smith GC Cheeseman CL 《Veterinary journal (London, England : 1997)》2003,166(1):43-51
Bovine tuberculosis (TB) is a serious zoonotic disease, which despite a largely successful test and slaughter programme has persisted in cattle herds in parts of the UK. The badger (Meles meles) is widely considered to represent a significant wildlife reservoir for the transmission of Mycobacterium bovis to cattle, and has been the subject of a variety of culling strategies since the mid 1970s. Nevertheless, the incidence of herd breakdowns has continued to rise, and the efficacy of culling is currently the subject of a large-scale field trial. One potential alternative tool for the management of disease in wildlife populations is vaccination. However, the successful development of an effective vaccine and a strategy for its delivery will require careful consideration of the practical constraints imposed by ecological factors. In the current paper, we discuss relevant ecological and epidemiological characteristics of badger populations and practical aspects of vaccine delivery in the field. 相似文献
129.
Fosgate GT Adesiyun AA Hird DW Johnson WO Hietala SK Schurig GG Ryan J 《American journal of veterinary research》2003,64(1):57-64
OBJECTIVE: To estimate receiver-operating characteristic (ROC) curves for a competitive ELISA (c-ELISA) that is used in serodiagnosis of brucellosis in water buffalo and cattle, to determine the most appropriate positive cutoff value for the c-ELISA in confirmation of infection, and to evaluate species differences in c-ELISA function. SAMPLE POPULATION: Sera from 4 herds of cattle (n = 391) and 4 herds of water buffalo (381). PROCEDURE: Serum samples were evaluated for Brucella-specific antibodies by use of a c-ELISA. On the basis of previous serologic test results, iterative simulation modeling was used to classify animals as positive or negative for Brucella infection without the use of a gold standard. Accuracy of c-ELISA for diagnosis of infection was compared between cattle and water buffalo by comparison of areas under ROC curves. RESULTS: A positive cutoff value of 30% inhibition for c-ELISA yielded sensitivity and specificity estimates, respectively, of 83.9 and 92.6% for cattle and 91.4 and 95.4% for water buffalo. A positive cutoff value of 35% inhibition yielded sensitivity and specificity estimates, respectively, of 83.9 and 96.2% for cattle and 88.0 and 974% for water buffalo. Areas under ROC curves were 0.94 and 0.98 for cattle and water buffalo, respectively. CONCLUSIONS AND CLINICAL RELEVANCE: ROC curves can be estimated by use of iterative simulation methods to determine optimal cutoff values for diagnostic tests with quantitative outcomes. A cutoff value of 35% inhibition for the c-ELISA was found to be most appropriate for confirmation of Brucella infection in cattle and water buffalo. 相似文献
130.
Wilson GH Greene CE Greenacre CB 《Journal of the American Veterinary Medical Association》2003,222(8):1093-6, 1077
A 1.5-year-old ferret examined because of seizures was found to have low serum calcium, high serum phosphorus, and extremely high serum parathyroid hormone concentrations. Common causes of these abnormalities, including nutritional secondary hyperparathyroidism, chronic renal secondary hyperparathyroidism, tumor lysis syndrome, and hypomagnesemia, were ruled out, and a tentative diagnosis of pseudohypoparathyroidism was made. Pseudohypoparathyroidism is a hereditary condition in people that, to our knowledge, has not been identified in ferrets previously and is caused by a lack of response to high serum parathyroid hormone concentrations, rather than a deficiency of this hormone. The ferret improved after treatment with dihydrotachysterol (a vitamin D analog) and calcium carbonate. It was still doing well after 3.5 years of continued treatment. 相似文献