全文获取类型
收费全文 | 5549篇 |
免费 | 233篇 |
国内免费 | 13篇 |
专业分类
林业 | 401篇 |
农学 | 233篇 |
基础科学 | 39篇 |
660篇 | |
综合类 | 579篇 |
农作物 | 211篇 |
水产渔业 | 218篇 |
畜牧兽医 | 3033篇 |
园艺 | 45篇 |
植物保护 | 376篇 |
出版年
2019年 | 45篇 |
2018年 | 68篇 |
2017年 | 102篇 |
2016年 | 87篇 |
2015年 | 58篇 |
2014年 | 82篇 |
2013年 | 205篇 |
2012年 | 157篇 |
2011年 | 178篇 |
2010年 | 112篇 |
2009年 | 123篇 |
2008年 | 220篇 |
2007年 | 214篇 |
2006年 | 183篇 |
2005年 | 206篇 |
2004年 | 180篇 |
2003年 | 185篇 |
2002年 | 174篇 |
2001年 | 205篇 |
2000年 | 199篇 |
1999年 | 185篇 |
1998年 | 54篇 |
1997年 | 73篇 |
1996年 | 66篇 |
1995年 | 57篇 |
1994年 | 47篇 |
1993年 | 63篇 |
1992年 | 127篇 |
1991年 | 136篇 |
1990年 | 135篇 |
1989年 | 138篇 |
1988年 | 108篇 |
1987年 | 122篇 |
1986年 | 103篇 |
1985年 | 97篇 |
1984年 | 93篇 |
1983年 | 67篇 |
1982年 | 39篇 |
1979年 | 81篇 |
1978年 | 63篇 |
1977年 | 73篇 |
1976年 | 46篇 |
1975年 | 69篇 |
1974年 | 85篇 |
1973年 | 74篇 |
1972年 | 75篇 |
1971年 | 56篇 |
1970年 | 70篇 |
1969年 | 51篇 |
1968年 | 44篇 |
排序方式: 共有5795条查询结果,搜索用时 109 毫秒
21.
The effects of sufficient milk intake as well as of 32 hours of fasting after birth, administration of actinomycin D (intraperitoneal application of 1 mg/kg five weight), and fasting in combination with actinomycin D on the development of body and liver weights, crude protein levels in homogenate and supernatant of liver, kidneys, and M. semitendinosus as well as on the activities of certain tissue enzymes were analysed with four groups of piglets (n = 4). Fasting, administration of actinomycin, and fasting in combination with actinomycin D resulted in rapid reduction in body and liver weights, while the crude protein levels in those tissues were not affected with significance. GOT and fructose-1,6-diphosphatase activities in supernatant from liver tended to decline under fasting conditions. The ATPase activity in the homogenate of the above tissues did not change in response to differentiated treatment. 相似文献
22.
23.
24.
In a consecutive and non-selected study of 54 kidney transplanted dogs, 12 cases of intussusception of the small intestine developed in 8 dogs. The patogenesis is still unknown. It has been postulated that the time of the operation (4--7 hours) and the segmental termination of the post-operative atony in the intestine are essential factors in this fatal complication. The last 16 dogs in this material were peroperatively treated with antikolinergics (Mestinon NFN), which was continued until normal function of the intestine. In these dogs there were no evidence of intussusception. The value of this profylaxis is open to discussion and it is essential to solve the problem of intussusception through a "blind" and controlled trial. 相似文献
25.
With ileum cannulated sows were tested the apparent precaecal and faecal digestibility of crude nutrients from raw and thermically treated fodder sugar beets of size "Rosamona". Two samples from two different harvest years, differing extremely in the content of disaccharides were tested. The crude nutrient digestibility affected stronger by content of sucrose then by treatment. Fodder sugar beets with contents of disaccharide lower then 400 g/kg DM showed low precaecal and faecal digestibilities. A longer cooling phase decreased the feed value of steamed beets through the microbial attack in the formation of precaecal indigestible sugar alcohols (mannitol). 相似文献
26.
An account is given of various techniques of blood sampling in the context of certain mustelids, including cardiopuncture, amputation of tail tip, talon cutting, incision of the ear vein, puncture of the jugular or femoral vein, and catheterisation of the abdominal aorta. Reference is made to details of use of all techniques, characteristics, advantages and potential setbacks, and preferable use of some of the tested methods to collect blood from mustela and martes species. Blood collection from the abdominal aorta may be helpful in obtaining no-haemolysis and no-additive plasma for biochemical multi-screening. Biochemical, pharmacological, and toxicological follow-up checks may be feasible under certain conditions following surgical exposure of the external jugular vein. The use of "Fimomed" (n-butylcyano-acrylate), a tissue adhesive, may help to reduce effort in terms of time and material and consequently, rationalise veterinary hygiene action as a whole, provided that the conditions for its application are observed. The skin adhesive is properly applicable to skin lesions of mustelids. A combination of suturing with adhesive should be used to close laparotomy wounds for better mechanical strength of the abdominal wall. Possible applications of "Fimomed" should be tested with other species as well. 相似文献
27.
28.
29.
H. Neubauer L. D. Sprague R. Zacharia H. Tomaso S. Al Dahouk R. Wernery U. Wernery H. C. Scholz 《Zoonoses and public health》2005,52(5):201-205
Burkholderia mallei causes glanders or farcy in solipeds, a disease that must be reported to the OIE (Office International des Epizooties, Paris, France). The number of reported outbreaks has increased steadily during the last decade. Serodiagnosis is hampered by the considerable number of false‐positives and ‐negatives of the internationally prescribed tests. The major problem leading to low sensitivity and specificity of complement fixation test (CFT) and enzyme‐linked immunosorbent assay (ELISA) has been linked to the test antigens currently used, i.e. crude preparations of whole cells. Future perspectives for the development and evaluation of serological test kits using well‐characterized single antigens are discussed in the light of recent molecular research on B. mallei and the closely related saprozoonotic agent B. pseudomallei. 相似文献
30.
A mathematical model has been developed for the risk assessment of the spread of genes conferring herbicide resistance in plant populations. The model combines an age-and-stage-structured population dynamic model, a population genetic model and a model of spatial spread. This is achieved by embedding a local matrix population model into a cellular automaton model with raster cells as spatial units. The dynamics of each cell is determined by both its local dynamics and the interaction with neighbouring cells. The model is applied to the evaluation of management strategies to delay or even to prevent long-term evolution of resistance in an annual grass weed. The results show that the appearance and spread of resistant genes is a highly non-linear process exhibiting threshold phenomena, which occur for a wide range of parameters. The properties of the seed survival curve constitute the `genetic memory' of the system and thus determine its long-term dynamics. It is possible to delay the evolution of resistance by suspension of treatment, reduction in herbicide application rate and introducing fallow periods. Spatial spread from an infested plot is inhibited by leaving untreated strips between adjacent fields. 相似文献