全文获取类型
| 收费全文 | 3932篇 |
| 免费 | 845篇 |
| 国内免费 | 61篇 |
专业分类
| 林业 | 469篇 |
| 农学 | 346篇 |
| 基础科学 | 279篇 |
| 592篇 | |
| 综合类 | 1948篇 |
| 农作物 | 211篇 |
| 水产渔业 | 176篇 |
| 畜牧兽医 | 532篇 |
| 园艺 | 133篇 |
| 植物保护 | 152篇 |
出版年
| 2025年 | 45篇 |
| 2024年 | 85篇 |
| 2023年 | 80篇 |
| 2022年 | 93篇 |
| 2021年 | 134篇 |
| 2020年 | 127篇 |
| 2019年 | 155篇 |
| 2018年 | 89篇 |
| 2017年 | 164篇 |
| 2016年 | 196篇 |
| 2015年 | 148篇 |
| 2014年 | 278篇 |
| 2013年 | 240篇 |
| 2012年 | 397篇 |
| 2011年 | 369篇 |
| 2010年 | 291篇 |
| 2009年 | 279篇 |
| 2008年 | 219篇 |
| 2007年 | 264篇 |
| 2006年 | 177篇 |
| 2005年 | 159篇 |
| 2004年 | 122篇 |
| 2003年 | 107篇 |
| 2002年 | 81篇 |
| 2001年 | 72篇 |
| 2000年 | 68篇 |
| 1999年 | 57篇 |
| 1998年 | 38篇 |
| 1997年 | 26篇 |
| 1996年 | 48篇 |
| 1995年 | 33篇 |
| 1994年 | 34篇 |
| 1993年 | 30篇 |
| 1992年 | 39篇 |
| 1991年 | 26篇 |
| 1990年 | 16篇 |
| 1989年 | 11篇 |
| 1988年 | 11篇 |
| 1987年 | 13篇 |
| 1986年 | 3篇 |
| 1985年 | 5篇 |
| 1984年 | 1篇 |
| 1983年 | 1篇 |
| 1981年 | 1篇 |
| 1979年 | 1篇 |
| 1977年 | 3篇 |
| 1962年 | 1篇 |
| 1956年 | 1篇 |
排序方式： 共有4838条查询结果，搜索用时 15 毫秒
1.
Peter Howgate 《Journal Of Aquatic Food Product Technology》2013,22(1):2-15
Procedures for sensory evaluation of fish often give the appearance of being empirical, that is, having been developed from practice without any contribution of underlying theory. The fundamental principles of sensory evaluation lie in psychophysics, a branch of psychology. Some textbooks of sensory evaluation have sections on psychophysics, but they are based on what might be called classical psychophysics which is summarized by the Weber/Fechner laws. Contemporary psychophysics has theories and practices which have wider applications in sensory evaluation of foods than classical psychophysics and can be applied to the advantage in the sensory analysis of fish. Three examples from the author's own experience will be presented in this discussion paper: use of the Theory of Signal Detection in evaluating taints; use of similarity ranking methods and multidimensional scaling for grouping fish by sensory properties; and application of current ideas of scaling to the measurement of freshness. 相似文献
2.
Takeyuki OZAWA Kumiko MUKUDA Masaru FUJITA Jiro NISHITANI 《Animal Science Journal》2009,80(2):212-219
A consumer questionnaire conducted with the purpose of ascertaining the acceptability of goat milk and related products in Japan was carried out on 345 guarantees of Nippon Veterinary and Life Science University in December 2006. 275 effective responses (79%) representing middle class urban households were returned. The results revealed that (1) 30% of respondents have experienced drinking goat milk and only 10% are aware of the current retail situation of goat milk and related products; (2) over 70% of goat milk drinkers raised goats by hand at some point in their past and their first experience drinking goat milk was in infancy; (3) those with experience in drinking goat milk expressed a vague evaluation and minimal understanding of drinking goat milk; (4) respondents who were inexperienced goat milk drinkers expressed a strong desire to taste and a weak desire to purchase goat milk; (5) respondents expressed low recognition regarding retailed goat milk products, but those who had already purchased goat milk products expressed a high evaluation and strong desire to purchase these products again; and (6) recognition of goat milk characteristics is low, but those with high recognition also rate goat milk highly. Goats are perceived as being 'mild and familiar.' It is necessary for those who manage goat husbandry to present goat milk and related product tasting opportunities to consumers. The key point is to make the functional differences between cow and goat milk clear and present the advantages of goat milk at the fore of this promotion. Goat milk should not be promoted merely as a drink that is similar to cow milk, but must be positioned as a functional drink or health food in order to expand the Japanese goat milk market. 相似文献
3.
Ceruloplasmin (Cp) determination could provide an objective measure of the health status of an animal and could be used as marker of animal health and welfare (Skinner, 2001) (Skinner, J. G., 2001. Special report. International standardization of acute phase proteins. Veterinary Clinical Pathology 30, 2-7.) but only manual methods have been reported to determine Cp concentrations in pigs (McCosker, 1961; Toussaint et al., 1995; Eckersall et al., 1996) (McCosker, P. J., 1961. Paraphenylenediamine oxidase activity and copper-levels in mammalian plasmas. Nature. 190, 887-889; Toussaint, M. J. M., Van Ederen, A. M., Gruys, E., 1995. Implication of clinical pathology in assessment of animal health and in animal production and meat inspection. Comparative Haematology International 5, 149-157; Eckersall, P. D., Saini, P. K., McComb, C., 1996. The acute phase response of acid soluble glycoprotein, alpha(1)-acid glycoprotein, ceruloplasmin, haptoglobin and C-reactive protein, in the pig. Veterinary Immunology and Immunopathology 51, 377-385). In the present study two automated methods based on the use of two different substrates for the determination of serum ceruloplasmin in pigs were developed, evaluated and compared. Both methods showed a good precision and detection limits, with no signs of inaccuracy and could be applied to biochemical autoanalyzers usually found in clinical laboratories using only minimal amounts of serum. Additionally the behaviour of Cp in experimental and clinical situations was studied showing an increase of around two fold after turpentine administration and significantly higher values in cases of pigs with inflammatory conditions when compared with healthy pigs. 相似文献
4.
林兰华 《东北林业大学学报》2000,28(2):85-87
给出了用于求解结构动力响应的基于不协调时间有限元方法的算法公式。以及采用三次Ｈｅｒｍｉｔｅ插值多项式逼近状态变量。应用时间不连续的Ｇａｌｅｒｋｉｎ方法推导出的一个单步递推断算法公式。同时给出了与Ｎｅｗｍａｋ的梯形法则、ＨＨＴ－α等几种算法的数值比较。 相似文献
5.
James Sedalia Peters David T. Damery Richard W. Wilkie 《Journal of Sustainable Forestry》2017,36(1):76-89
The article presents a material-geographic study of contemporary log home manufacturing in the Eastern Woodlands of North America. The study investigated relationships between log conversion (i.e., processing) methods and regional location. Manufacturers were grouped by their conversion methods, using hierarchical cluster analysis; and analyzed for spatial correlation, using standard deviational ellipses (SDEs). Tree species utilization, log treatment, horizontal surface type, and corner notch type were found to be spatially differentiating. These attributes were tested for their ability to predict manufacturers’ culture region using multinomial logistic regression (MLR) models. Tree species utilization was an independent variable in all of the predictive models, suggesting a correspondence between building culture and ecological regions. This is consistent with earlier research. The findings suggest that location drives tree species utilization and, thereby, building methods. Like the eco-region itself, log conversion methods vary on a north-south gradient. It is argued that construction knowledge is geo-contextual and that the replacement of scientific wood extraction with ecosystem management as the central paradigm in forestry calls for geo-contextual approaches to sustainability in the construction industry. 相似文献
6.
在计算机仿真试验中初始状态的设置非常重要 ,本文结合实例 ,提出了设置初始状态的几种方法 ,并探讨了各自的适用条件 相似文献
7.
乌兰县防沙治沙工程和"三北"防护林工程相结合,有效地遏制沙漠化,使局部生态环境得到改善,本文介绍了采用植物治沙的一些造林方法及一些建议。 相似文献
8.
9.
Coarse woody debris (CWD) has been recognized as one of the strongest indicators of forest biodiversity and its assessment has been emphasized in the development of new inventory methods. In this study, the most commonly referenced probability sampling methods were tested in a field area of 305.8 ha to gain comparative information on their performance and efficiency. Simple random sampling (SRS), systematic sampling and cluster sampling with fixed sized circular sample plots were tested, as well as strip sampling, transect relascope sampling and adaptive cluster sampling (ACS). Point relascope sampling and line intersect sampling were also tested for inventories of downed dead wood volumes. In addition, the amount of standing dead wood was assessed by means of traditional small angle relascope sampling. In general, the use of additional information in the inventory process has shown promising results. A new method for using data derived from airborne laser scanning (ALS) as a source of auxiliary information in the assessment of CWD volumes is presented, using probability proportional to size (PPS) sampling for the selection of the first-stage sample units in ACS (ACSPPS) and for the placement of fixed sized plots (PLOTPPS). The sampling methods were compared in terms of the cost-effectiveness. Point relascope sampling proved the most efficient sampling method for inventorying CWD volumes. PLOTPPS and ACSPPS were more efficient than the inventory of fixed sized plots (PLOTSRS) and ACS (ACSSRS) where sample units were selected with SRS. However, these methods could not achieve the same efficiency as relascope samplings. Nevertheless, the use of probability layers derived from ALS data gave promising results and offers new possibilities for inventorying CWD volumes more efficiently. 相似文献
10.
中国饮茶方式历经了由唐以前的生煮羹饮、唐代的煎茶、宋代的点茶到明清瀹饮法的漫漫演进,中国饮茶方式的历史演变也是中华茶文化发展进程的缩影,也是中华茶文化的精华所在。 相似文献