全文获取类型
收费全文 | 2027篇 |
免费 | 63篇 |
国内免费 | 28篇 |
专业分类
林业 | 203篇 |
农学 | 144篇 |
基础科学 | 19篇 |
470篇 | |
综合类 | 290篇 |
农作物 | 204篇 |
水产渔业 | 86篇 |
畜牧兽医 | 510篇 |
园艺 | 84篇 |
植物保护 | 108篇 |
出版年
2023年 | 14篇 |
2022年 | 54篇 |
2021年 | 86篇 |
2020年 | 80篇 |
2019年 | 96篇 |
2018年 | 82篇 |
2017年 | 99篇 |
2016年 | 108篇 |
2015年 | 121篇 |
2014年 | 112篇 |
2013年 | 188篇 |
2012年 | 138篇 |
2011年 | 134篇 |
2010年 | 132篇 |
2009年 | 115篇 |
2008年 | 124篇 |
2007年 | 97篇 |
2006年 | 67篇 |
2005年 | 38篇 |
2004年 | 28篇 |
2003年 | 22篇 |
2002年 | 17篇 |
2001年 | 25篇 |
2000年 | 6篇 |
1999年 | 17篇 |
1998年 | 4篇 |
1997年 | 5篇 |
1996年 | 5篇 |
1995年 | 6篇 |
1993年 | 4篇 |
1992年 | 8篇 |
1991年 | 4篇 |
1990年 | 5篇 |
1989年 | 8篇 |
1988年 | 7篇 |
1987年 | 6篇 |
1985年 | 3篇 |
1984年 | 3篇 |
1983年 | 3篇 |
1981年 | 3篇 |
1974年 | 2篇 |
1972年 | 2篇 |
1971年 | 2篇 |
1970年 | 2篇 |
1966年 | 2篇 |
1964年 | 2篇 |
1959年 | 2篇 |
1936年 | 2篇 |
1928年 | 2篇 |
1857年 | 2篇 |
排序方式: 共有2118条查询结果,搜索用时 20 毫秒
971.
Romain Javard Swan Specchi Jér?me Benamou Catherine Lapointe Jean-Baptiste Deffontaines Jér?me Planté Marc-André d’Anjou 《The Canadian veterinary journal. La revue veterinaire canadienne》2014,55(11):1096-1099
This report describes an ileocecocolic volvulus in a German shepherd dog with risk factors of previous abdominal surgeries and concurrent chronic enteropathy. Contrast-enhanced computed tomography (CT) with multiplanar reformatting was more sensitive than abdominal radiographs or ultrasound to obtain a diagnosis, because of the presence of a “whirl-sign” on CT. A combination of colopexy and cecopexy was succesfully used to treat the patient’s condition. 相似文献
972.
G. A. Larionov O. G. Bushueva N. G. Dobrovol’skaya Z. P. Kiryukhina S. F. Krasnov L. F. Litvin R. R. Murataev 《Eurasian Soil Science》2010,43(4):453-458
The rates of the soil loss were studied in a wide range of flow velocities from 0.41 to 1.64 m/s. The results confirmed the
main implications of the hydrophysical model: (1) the rate of the soil loss in the region of flow velocities exceeding the
threshold value by 1.2–1.5 times and more is proportional to the cubic flow velocity; (2) the detachment of particles in the
pre-threshold region is probable in nature, and the relationship between the soil loss and flow velocity is S-shaped. On this
basis, a procedure was developed for the experimental determination of the soil erosion parameters: the erodibility, the threshold
flow velocity, and the coefficient characterizing the variance of the particles’ resistance to detachment. 相似文献
973.
The influence of aeration and temperature on the structure of bacterial complexes in high-moor peat soil 总被引:1,自引:0,他引:1
O. S. Kukharenko N. S. Pavlova T. G. Dobrovol’skaya A. V. Golovchenko T. N. Pochatkova G. M. Zenova D. G. Zvyagintsev 《Eurasian Soil Science》2010,43(5):573-579
The number and taxonomic structure of the heterotrophic block of aerobic and facultative anaerobic bacteria were studied in
monoliths from a high-moor peat (stored at room temperature and in a refrigerator) and in the peat horizons mixed in laboratory
vessels. The monitoring lasted for a year. In the T0 horizon, spirilla predominated at room and low temperatures; in the T1
and T2 horizons, bacilli were the dominants. The continuous mixing of the peat layers increased the oxygen concentration and
the peat decomposition; hence, the shares of actinomycetes and bacilli (bacteria of the hydrolytic complex) increased. In
the peat studied, the bacilli were in the active state; i.e., vegetative cells predominated, whose amount ranged from 65 to
90%. The representatives of the main species of bacilli (the facultative anaerobic forms prevailed) hydrolyzed starch, pectin,
and carboxymethylcellulose. Thus, precisely sporiferous bacteria can actively participate in the decomposition of plant polysaccharides
in high-moor peat soils that are characterized by low temperatures and an oxygen deficit. The development of actinomycetes
is inhibited by low temperatures; they can develop only under elevated temperature and better aeration. 相似文献
974.
T. G. Dobrovol’skaya M. V. Gorlenko A. L. Stepanov S. A. Nesterov A. V. Tiunov 《Moscow University Soil Science Bulletin》2010,65(3):128-132
A field experiment showed that long-term addition of easily accessible carbon (sucrose) into soil leads to an abrupt reduction
in the number of cellulose-degrading bacteria but to an increase in the functional diversity of the soil microbial community
along with an increase in carbon dioxide emission, nitrogen fixation, and denitrification. The exclusion of ectomycorrhizal
spruce roots did not affect the number of hydrolytic bacteria but stimulated nitrogen fixation and decreased the intensity
of basal respiration and denitrification activity of the soil. 相似文献
975.
976.
Ryuichi TATSUMI Kei MITSUHASHI Ken ASHIDA Atsushi HARUNO Akihito HATTORI Yoshihide IKEUCHI Ronald E. ALLEN 《Animal Science Journal》2004,75(4):345-351
It has previously been shown that mechanical stretch induces activation of cultured quiescent satellite cells by rapid release of hepatocyte growth factor (HGF) from its extracellular association with satellite cells and its subsequent presentation to the c‐met receptor. The present study provides evidence that the stretch activation activity varies according to the origin of satellite cells from back and leg skeletal muscles in vitro. Satellite cells were isolated from three muscle groups, back (BK), upper hind limb (UL) and lower hind limb (LL) muscles, of adult male rats and stretch activation activities were compared. In response to stretch, lower hind limb satellite cells showed significantly greater response than upper hind limb and back muscles (LL > UL > BK). Immunoblots of stretched culture media revealed a higher HGF‐releasing capacity of lower hind limb satellite cells than back muscle satellite cells. In addition, lower hind limb satellite cells exhibited a greater activation activity in response to exogenous HGF added to culture media than compared to satellite cells from back and upper hind limb (LL > UL > BK). The increased ability to release HGF and the increased cellular responsiveness might account for higher stretch activation activities of lower hind limb satellite cells. Electrophoretic analysis of myosin heavy chain isoforms verified a higher content of slow muscle fibers in lower limb muscles (LL > UL > BK), suggesting a difference in stretch‐induced activation activity between satellite cells associated with fast and slow muscle fibers. 相似文献
977.
On crossing Simmental cows with Holstein bulls, preslaughter weight, raw hide weight, carcass weight, and dressing percentage increased compared with the indices of Simmental bulls. Meatiness and muscling of the thigh were higher. 相似文献
978.
The paper shows results of the investigation of quantitative parameters of changes in common and readily decomposable organic matter in the sod-podzolic sandy loam soil under long-term use of straw of cereals and legumes as fertilizer for two 5-field grain-row crop rotations. 相似文献
979.
A. P. Batudaev V. M. Korshunov B. B. Tsybikov N. N. Mal’tsev 《Russian Agricultural Sciences》2010,36(6):449-451
A high effectiveness of fallows occupied by yellow sweetclover, which provide a spring wheat yield at the level of a clean fallow, is revealed in field crop rotations under conditions of the steppe zone. 相似文献
980.