全文获取类型
收费全文 | 153460篇 |
免费 | 7822篇 |
国内免费 | 70篇 |
专业分类
林业 | 9191篇 |
农学 | 5910篇 |
基础科学 | 1004篇 |
21087篇 | |
综合类 | 20191篇 |
农作物 | 7149篇 |
水产渔业 | 8884篇 |
畜牧兽医 | 74246篇 |
园艺 | 2750篇 |
植物保护 | 10940篇 |
出版年
2020年 | 1194篇 |
2019年 | 1432篇 |
2018年 | 4925篇 |
2017年 | 5199篇 |
2016年 | 3471篇 |
2015年 | 2089篇 |
2014年 | 2488篇 |
2013年 | 5757篇 |
2012年 | 5186篇 |
2011年 | 7432篇 |
2010年 | 5783篇 |
2009年 | 5045篇 |
2008年 | 6645篇 |
2007年 | 6857篇 |
2006年 | 4681篇 |
2005年 | 4387篇 |
2004年 | 4231篇 |
2003年 | 4365篇 |
2002年 | 3904篇 |
2001年 | 4779篇 |
2000年 | 4690篇 |
1999年 | 3749篇 |
1998年 | 1474篇 |
1997年 | 1454篇 |
1996年 | 1343篇 |
1995年 | 1600篇 |
1994年 | 1328篇 |
1993年 | 1377篇 |
1992年 | 2790篇 |
1991年 | 2901篇 |
1990年 | 2867篇 |
1989年 | 2912篇 |
1988年 | 2622篇 |
1987年 | 2593篇 |
1986年 | 2540篇 |
1985年 | 2400篇 |
1984年 | 1956篇 |
1983年 | 1716篇 |
1982年 | 1154篇 |
1979年 | 1649篇 |
1978年 | 1284篇 |
1977年 | 1149篇 |
1976年 | 1100篇 |
1975年 | 1164篇 |
1974年 | 1357篇 |
1973年 | 1448篇 |
1972年 | 1379篇 |
1971年 | 1196篇 |
1970年 | 1247篇 |
1969年 | 1148篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
121.
122.
Nemadectin, a new broad-spectrum endectocide, was highly efficacious against natural infections of all the major canine gastrointestinal helminths. At single oral dosages of 0.2-0.4 mg kg-1 body weight (BW), a liquid formulation administered in gelatin capsules was 100% effective in eliminating natural infections of Toxocara canis, Toxascaris leonina, Ancylostoma caninum and Uncinaria stenocephala. Tablets (267 mg) containing 4.6% nemadectin given at a rate of 1/3 tablet per 20 kg BW (0.2 mg nemadectin kg-1) were 100% active against T. canis, A. caninum and U. stenocephala. With both formulations, an increase in the dose rate to 0.6-0.8 mg kg-1 BW resulted in 99-100% elimination of Trichuris vulpis infections. No adverse reactions were observed in any of the treated dogs. 相似文献
123.
J Vercruysse J Fransen M van Goubergen 《Zentralblatt für Veterin?rmedizin. Reihe B. Journal of veterinary medicine. Series B》1989,36(2):148-153
Muscle tissue from the oesophagus, diaphragm and heart of 100 cattle slaughtered in Belgium was examined for Sarcocystis infection by microscopic examination of tissue and artificial digestion. Intact sarcocysts or cystozoietes were recovered from 97% of the cattle examined. There was a difference in sensitivity between the method (digestion or histology) used and the muscle processed. The digestion of the oesophagus muscle resulted in the highest number of positive animals whereas the heart muscles contained most cysts during histological examination. Thin-walled cysts were recovered from all positive animals especially in the heart and they were indistinguishable from those of S. cruzi. Thick-walled cysts were recovered from 56% of animals but these could not be identified as S. hirsuta and/or S. hominis on morphological grounds. A correlation between pathological changes and the infection grade could not be proved. 相似文献
124.
125.
126.
Described in this paper are 2 methodological variants for photometric recording of sperm aggregation. Heparin was used to induce aggregation. One of the working principles was related to aggregation-associated alteration of turbidity in an agitated cell suspension, measured by the KZM-1 coagulation-time meter, in analogy to measurement of thrombocyte aggregation. The 2nd variant was based on variation of cloudiness due to sedimentation of aggregates in a non-agitated suspension. Both methods provided equally valid information. They characterised both intensity of aggregation as a combined effect of the number and size of aggregates as well as the rate of aggregation. Photometric recording has proved to be an objectivated method for quantitative assessment of aggregation. Its use is proposed for studies into capacitation or immunological response of spermatozoa. 相似文献
127.
Smith HM 《Science (New York, N.Y.)》1926,63(1641):586-587
128.
129.
130.
Eidinoff ML 《Science (New York, N.Y.)》1948,108(2811):535-536