全文获取类型
收费全文 | 17211篇 |
免费 | 49篇 |
国内免费 | 4篇 |
专业分类
林业 | 3711篇 |
农学 | 1316篇 |
基础科学 | 144篇 |
2913篇 | |
综合类 | 784篇 |
农作物 | 2141篇 |
水产渔业 | 1857篇 |
畜牧兽医 | 1351篇 |
园艺 | 1129篇 |
植物保护 | 1918篇 |
出版年
2023年 | 10篇 |
2022年 | 23篇 |
2021年 | 47篇 |
2020年 | 36篇 |
2019年 | 44篇 |
2018年 | 2768篇 |
2017年 | 2735篇 |
2016年 | 1205篇 |
2015年 | 93篇 |
2014年 | 43篇 |
2013年 | 40篇 |
2012年 | 840篇 |
2011年 | 2204篇 |
2010年 | 2134篇 |
2009年 | 1286篇 |
2008年 | 1367篇 |
2007年 | 1622篇 |
2006年 | 78篇 |
2005年 | 131篇 |
2004年 | 133篇 |
2003年 | 176篇 |
2002年 | 84篇 |
2001年 | 12篇 |
2000年 | 44篇 |
1999年 | 4篇 |
1998年 | 3篇 |
1997年 | 2篇 |
1996年 | 3篇 |
1995年 | 4篇 |
1994年 | 3篇 |
1993年 | 13篇 |
1992年 | 9篇 |
1990年 | 4篇 |
1989年 | 7篇 |
1988年 | 11篇 |
1987年 | 3篇 |
1984年 | 2篇 |
1977年 | 4篇 |
1968年 | 4篇 |
1967年 | 2篇 |
1955年 | 2篇 |
1951年 | 2篇 |
1950年 | 5篇 |
1949年 | 3篇 |
1948年 | 1篇 |
1943年 | 2篇 |
1942年 | 2篇 |
1941年 | 4篇 |
1940年 | 2篇 |
1939年 | 3篇 |
排序方式: 共有10000条查询结果,搜索用时 9 毫秒
1.
Marc Govaerts Peter Verhaert Frans Jongejan Bruno M Goddeeris 《Veterinary parasitology》2002,104(2):103-117
The immunodominant 33/35kDa antigen of a Theileria isolate from West Java, Indonesia, was characterised and immuno-affinity purified by use of a monoclonal antibody, KUL-a4, and was shown to be representative of the T. orientalis/sergenti/buffeli group. The aminoterminal sequence of the purified 35kDa peptide (20 residues) was determined by automated Edman degradation and found to correspond to the predicted amino acid sequence of a prospective p33 gene previously sequenced from the same isolate. The cleavage site of a putative signal peptide was identified and conforms the (-3, -1) rule for signal peptidases. The existence of dimeric and trimeric forms of the p33/35 antigen is hypothesised from Western blot profiles. KUL-a4 appeared specific for the T. orientalis/sergenti/buffeli group. It did not recognise in indirect fluorescence antibody test (IFAT), intraerythrocytic bodies of Anaplasma marginale or piroplasms and schizonts of T. mutans, T. parva and T. annulata, whereas cattle antisera raised to these species showed cross-reactivity in IFAT. It however, appeared weakly cross-reactive in Western blot and ELISA, with the 34kDa piroplasm antigen of one T. annulata (Gharb) isolate. The present study indicates that the isolated antigen belongs to the p33/34 antigen family described within the T. sergenti/orientalis/buffeli group, and documents the group-specificity of one of its epitopes. 相似文献
2.
Bruno Huber 《Forstwissenschaftliches Centralblatt》1949,68(7-8):456-468
Ohne ZusammenfassungMit 7 Abbildungen 相似文献
3.
4.
Journal of Pest Science - 相似文献
5.
6.
Cristina E. Almeida-Naranjo Patricio J. Espinoza-Montero Marcelo I. Muñoz-Rodríguez Cristina A. Villamar-Ayala 《Water, air, and soil pollution》2017,228(7):253
Hydraulic retention time (HRT) influence improving sludge flocculation with adding the polyelectrolytes (non-ionic, anionic, and cationic) was studied on an activated sludge (AS) system fed with synthetic domestic wastewater (SDW), dairy industry wastewater (DIW), and caramel industry wastewater (CIW). The sludge volumetric index, food/microorganism ratio (F/M), and mixed liquor volatile suspended solids at different HRTs (6, 8 and 10 h) were monitored on an experimental model. Results showed that both SDW and IW had the best sludge flocculation conditions at 8 h and 100 mL of non-ionic polyelectrolyte (0.2 mg L?1). In addition, this phenomenon reached the organic matter removal efficiencies of 95.9, 95.7, and 94.2% for SDW, DIW, and CIW, respectively. Therefore, optimum HRT increased the organic matter removal efficiencies by 10%, sludge concentration by 37% (22–55%), and F/M ratio by 70%. Moreover, the polyelectrolytes used in AS improved the sludge flocculation by 2.9 times. 相似文献
7.
Stacy N. Galleher Matthew R. Gilg Kelly J. Smith 《Fish physiology and biochemistry》2010,36(3):731-740
Fundulus heteroclitus and F. grandis are resident salt marsh fishes that overlap in distribution over a narrow range in northeastern Florida. The objective of
the present study was to examine whether the limits of the species’ ranges could be explained by differences in thermal tolerance.
Two populations of each species were collected and then spawned in the laboratory, and 9-day-old larvae were used for critical
thermal maxima trials. Mean LOE temperatures of larvae ranged from 43.04 to 43.65°C and showed little difference between species.
Therefore, differences in high temperatures experienced cannot account for the differences of the distributions of the two
species. Condition-specific competition may play a greater role in determining the observed range of the two species. 相似文献
8.
This paper presents empirical evidence on the impact of socio-economic factors on the adoption of agroforestry practices in
Cameroon. The analysis uses primary farm-level data collected from June to December 1996. Three major provinces of the country
were covered, namely Centre, Southwest and Northwest Several agroforestry technologies have been promoted among farmers in
the zone, including alley farming, improved fallow, live fencing, cut-and-carry fodder and apiculture. The status of adoption
of each agroforestry practice is described and factors that affect adoption identified. These are gender of farmer, household
family size, level of education, farmer’s experience, membership within farmers’ associations, contact with research and extension,
security of land tenure, agroecological zone, distance of the village from nearest town, village accessibility and income
from livestock. Research findings indicate that since factors affecting farmers’ adoption of agroforestry practices differ
across techniques, generalisation is to be avoided. 相似文献
9.
10.
Silvia P. Turner Tanja Maria Hess Kibby Treiber Erica B. Mello Bruno G. Souza Fernando Q. Almeida 《Journal of Equine Veterinary Science》2011,31(11):645-649
Diets high in concentrates and soluble carbohydrates are associated with reduced insulin sensitivity in horses. Exercise training could protect against diet-induced insulin resistance. The objective of this study was to determine the intensity of exercise training required to affect insulin sensitivity in stabled horses fed a diet high in concentrates but moderate in soluble carbohydrates. In all, 31 stabled horses underwent three different exercise regimens: turnout, light exercise, and moderate exercise, while being fed a diet containing 60% concentrate. Blood was sampled monthly and analyzed for insulin. Insulin sensitivity was assessed using basal insulin concentrations and calculated insulin sensitivity (reciprocal of the square root of insulin) and compared across months by analysis of variance with repeated measures. Insulin sensitivity (reciprocal of the square root of insulin) was higher during periods of moderate and light physical activity as compared with turnout. These results indicate that turnout alone may not be adequate to improve insulin sensitivity in horses fed high amounts of concentrate. 相似文献