全文获取类型
收费全文 | 5401篇 |
免费 | 227篇 |
国内免费 | 8篇 |
专业分类
林业 | 317篇 |
农学 | 161篇 |
基础科学 | 47篇 |
790篇 | |
综合类 | 862篇 |
农作物 | 262篇 |
水产渔业 | 467篇 |
畜牧兽医 | 2149篇 |
园艺 | 154篇 |
植物保护 | 427篇 |
出版年
2023年 | 35篇 |
2022年 | 51篇 |
2021年 | 103篇 |
2020年 | 121篇 |
2019年 | 131篇 |
2018年 | 92篇 |
2017年 | 105篇 |
2016年 | 100篇 |
2015年 | 112篇 |
2014年 | 131篇 |
2013年 | 255篇 |
2012年 | 288篇 |
2011年 | 360篇 |
2010年 | 194篇 |
2009年 | 157篇 |
2008年 | 359篇 |
2007年 | 298篇 |
2006年 | 307篇 |
2005年 | 317篇 |
2004年 | 272篇 |
2003年 | 277篇 |
2002年 | 269篇 |
2001年 | 65篇 |
2000年 | 73篇 |
1999年 | 72篇 |
1998年 | 51篇 |
1997年 | 44篇 |
1996年 | 42篇 |
1995年 | 38篇 |
1994年 | 47篇 |
1993年 | 54篇 |
1992年 | 48篇 |
1991年 | 37篇 |
1990年 | 41篇 |
1989年 | 37篇 |
1988年 | 34篇 |
1987年 | 38篇 |
1986年 | 30篇 |
1985年 | 36篇 |
1984年 | 41篇 |
1983年 | 36篇 |
1982年 | 20篇 |
1981年 | 35篇 |
1980年 | 26篇 |
1979年 | 27篇 |
1978年 | 22篇 |
1975年 | 20篇 |
1974年 | 25篇 |
1973年 | 27篇 |
1969年 | 19篇 |
排序方式: 共有5636条查询结果,搜索用时 15 毫秒
91.
A survey of sheep dipping in Scotland in 1978 showed that about 42 tonnes of organophosphorus and 17 tonnes of organochlorine insecticides were used to control ectoparasites. Information is presented about their pattern of use and about the disposal of surplus sheep dip and the empty containers. Six river pollution incidents involving sheep dips in 1978 are recorded. The main geographical areas affected by headfly (Hydrotaea irritans Fall.) and the measures taken against them are noted. 相似文献
92.
A method is presented which determines the bromide ion content of foodstuffs using a bromide specific ion electrode. For low levels of bromide (< 10 mg/kg) or for accurate work, bromide was extracted from the ground commodity with water and then separated from interfering compounds by ion-exchange chromatography before estimation. Alternatively, bromide ion can be estimated approximately by direct measurement on the aqueous extracts after heating to denature proteins. The method was checked against three standard methods of bromide estimation in foods, using wheat that had been repeatedly fumigated with methyl bromide. The equipment required is inexpensive and can be adapted for field use. The method has been used to determine the bromide and chloride contents that occur naturally in wheat, maize, copra, soya beans and sorghum. 相似文献
93.
James Waller 《Pest management science》1978,9(5):478-482
Bananas (including plantains) are widely grown throughout the tropics both for local consumption and for export. Pesticide usage is confined largely to the export crop because of its value and the susceptibility to diseases of varieties suitable for the export market. Most of the bananas grown for export are produced in Latin America and the Caribbean. Weed control with herbicides is particularly valuable in young banana plantations before a mature canopy is produced and when weeds compete with the shallow rooting system. Insecticides are used to control high populations of the banana weevil and may be used against fruit thrips. Nematicides are used extensively to control the banana root nematode and granular applications are now replacing soil injections. Fungicidal control of Sigatoka leaf diseases and fruit diseases has been practised for many years and is essential for the production of high quality, exportgrade fruit. Changes in the chemicals used and in application techniques have brought important benefits in recent years and genetic resistance is likely to play a large part in disease control in the future. 相似文献
94.
95.
L F James K R Van Kampen 《Journal of the American Veterinary Medical Association》1971,158(5):614-618
96.
d'Offay JM Floyd JG Eberle R Saliki JT Brock KV D'Andrea GH McMillan KL 《Journal of the American Veterinary Medical Association》2003,222(10):1404-7, 1366-7
Beef cattle from a herd in north Alabama were examined because of an outbreak of nonfatal skin disease characterized by discrete circumscribed areas of inflammation that developed on the skin from the neck to the hips. Areas of inflammation, which tended to be superficial, underwent necrosis and scabbed over. The scabs eventually dropped off leaving discrete, round, whitish, hairless lesions that were 1.2 to 2.5 cm diameter. Because clinical signs were consistent with those expected with pseudo-lumpy skin disease (PLSD) caused by bovine herpesvirus type 2 (BHV-2), samples from 16 representative animals were submitted for BHV-2 testing. All 16 animals were seropositive for BHV-2, but the virus could not be isolated from skin biopsy specimens or buffy coat samples. Results of a polymerase chain reaction assay incorporating primers designed to amplify 2 DNA sequences from BHV-2 were positive for 3 of the 10 cattle, suggesting that skin lesions in these cattle were a result of PLSD. Our findings suggest that PLSD may be more common and widespread in the United States than suggested by the frequency with which BHV-2 has been isolated from cattle with PLSD-like skin lesions. 相似文献
97.
Surgical removal of a mammary adenocarcinoma and a granulosa cell tumor in an African pygmy hedgehog 下载免费PDF全文
Wellehan JF Southorn E Smith DA Taylor WM 《The Canadian veterinary journal. La revue veterinaire canadienne》2003,44(3):235-237
A 3-year-old, female African pygmy hedgehog (Atelerix albiventris) was referred with a history of hematuria. Hyperglycemia and glucosuria were found at presentation. Mammary adenocarcinoma and a granulosa cell tumor were found and removed surgically. Glucosuria and hematuria resolved, and the hedgehog has done well for 10 mo postoperatively. 相似文献
98.
99.
100.