全文获取类型
收费全文 | 64269篇 |
免费 | 3340篇 |
国内免费 | 293篇 |
专业分类
林业 | 2509篇 |
农学 | 2173篇 |
基础科学 | 472篇 |
9003篇 | |
综合类 | 8993篇 |
农作物 | 2517篇 |
水产渔业 | 2822篇 |
畜牧兽医 | 34426篇 |
园艺 | 757篇 |
植物保护 | 4230篇 |
出版年
2021年 | 550篇 |
2020年 | 625篇 |
2019年 | 727篇 |
2018年 | 1210篇 |
2017年 | 1322篇 |
2016年 | 1182篇 |
2015年 | 918篇 |
2014年 | 1239篇 |
2013年 | 3219篇 |
2012年 | 2003篇 |
2011年 | 2438篇 |
2010年 | 1715篇 |
2009年 | 1707篇 |
2008年 | 2360篇 |
2007年 | 2191篇 |
2006年 | 1982篇 |
2005年 | 1698篇 |
2004年 | 1652篇 |
2003年 | 1594篇 |
2002年 | 1414篇 |
2001年 | 1877篇 |
2000年 | 1870篇 |
1999年 | 1385篇 |
1998年 | 600篇 |
1997年 | 608篇 |
1995年 | 629篇 |
1992年 | 1016篇 |
1991年 | 1151篇 |
1990年 | 1081篇 |
1989年 | 1113篇 |
1988年 | 982篇 |
1987年 | 961篇 |
1986年 | 1006篇 |
1985年 | 909篇 |
1984年 | 757篇 |
1983年 | 690篇 |
1979年 | 965篇 |
1978年 | 720篇 |
1977年 | 678篇 |
1976年 | 771篇 |
1975年 | 807篇 |
1974年 | 924篇 |
1973年 | 900篇 |
1972年 | 853篇 |
1971年 | 671篇 |
1970年 | 715篇 |
1969年 | 789篇 |
1968年 | 746篇 |
1967年 | 755篇 |
1966年 | 724篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
82.
83.
D. V. CLAY 《Weed Research》1980,20(2):97-102
The tolerance of strawberries to herbicides was tested by applications to the roots of plants growing in sand and by foliage applications to plants grown in compost, and compared with tolerance in the field. Dimefuron was safe as a foliar application but much more toxic than simazine when applied in sand or in the field. Metamitron caused slight injury as a foliar spray; in sand and in the field it was intermediate in toxicity between simazine and lenacil. At normal rates propachlor was safe as a foliar spray and much safer than lenacil when applied in sand. High rates had no adverse effect in the field. Ethofumesate and pendimethalin caused some temporary stunting when applied to foliage, but were less toxic than lenacil when applied to roots in sand. Field applications of both herbicides at 1–1.5 kg/ha were safe. Foliage sprays of bentazone, oxadiazon and oxyfluorfen severely damaged the sprayed leaves, but these herbicides were less active than lenacil when applied to the roots. In the field they caused severe leaf damage, but by the end of the growing season the plants had recovered. The experiments demonstrated the value of separate root and shoot activity tests for indicating which herbicides merit further field testing. 相似文献
84.
85.
86.
Wade N 《Science (New York, N.Y.)》1978,199(4324):30-1, 33
87.
P J Ihrke R M Schwartzman K McGinley L N Horwitz R R Marples 《American journal of veterinary research》1978,39(9):1487-1489
Quantitative and qualitative bacterial assays were performed on the skin of 15 normal and 32 seborrheic dogs. Nonionic detergent scrubs were made on areas demarcated by glass sidearm cylinders. Quantitative analysis was accomplished by the serial dilution technique, and the bacteria were identified by individual and colonial morphology and by enzyme production. Areas measured on control dogs had a markedly lower total bacterial count than similar areas measured on seborrheic animals. Control dogs had a flora consisting primarily of coagulase-negative cocci, whereas seborrheic dogs usually had a cutaneous flora composed primarily of Stahylococcus aureus, coagulase-positive. 相似文献
88.
89.
90.
Sunlight is known to reduce the incidence of blister blight disease of tea, caused by Exobasidium vexans . The effects of the ultraviolet-B (UV-B: 290–320 nm) component of solar radiation on the disease and the development of E. vexans were studied in the field in Sri Lanka using UV-screening filter materials held over a commercial crop. Exclusion of UV-B radiation by Polyester, which reduces fluxes in the UV-B region by approximately 75–85%, increased both the number of translucent spots (immature sites of infection) and number of sporulating blisters (mature sites of infection), but it had little or no effect on the sporulation of the pathogen. When basidiospores were artificially inoculated on leaves, and were exposed to full or filtered solar radiation, their survival and germination increased when UV-B wavelengths were removed; significant differences were found 62 h after inoculation. However, UV-B did not affect the extension of germ tubes. This study indicates that the UV-B component of solar radiation plays an important role in the natural regulation of blister blight disease in the field. 相似文献