全文获取类型
收费全文 | 1736篇 |
免费 | 105篇 |
国内免费 | 2篇 |
专业分类
林业 | 69篇 |
农学 | 38篇 |
基础科学 | 3篇 |
139篇 | |
综合类 | 367篇 |
农作物 | 54篇 |
水产渔业 | 84篇 |
畜牧兽医 | 984篇 |
园艺 | 23篇 |
植物保护 | 82篇 |
出版年
2023年 | 11篇 |
2021年 | 37篇 |
2020年 | 37篇 |
2019年 | 41篇 |
2018年 | 28篇 |
2017年 | 34篇 |
2016年 | 23篇 |
2015年 | 32篇 |
2014年 | 41篇 |
2013年 | 58篇 |
2012年 | 86篇 |
2011年 | 101篇 |
2010年 | 40篇 |
2009年 | 40篇 |
2008年 | 83篇 |
2007年 | 88篇 |
2006年 | 56篇 |
2005年 | 63篇 |
2004年 | 54篇 |
2003年 | 53篇 |
2002年 | 61篇 |
2001年 | 37篇 |
2000年 | 53篇 |
1999年 | 42篇 |
1997年 | 14篇 |
1996年 | 13篇 |
1992年 | 21篇 |
1991年 | 22篇 |
1990年 | 35篇 |
1989年 | 29篇 |
1988年 | 15篇 |
1987年 | 22篇 |
1986年 | 23篇 |
1985年 | 24篇 |
1984年 | 23篇 |
1983年 | 22篇 |
1982年 | 11篇 |
1981年 | 10篇 |
1980年 | 10篇 |
1979年 | 12篇 |
1978年 | 15篇 |
1977年 | 13篇 |
1975年 | 13篇 |
1974年 | 25篇 |
1973年 | 18篇 |
1972年 | 26篇 |
1971年 | 17篇 |
1970年 | 15篇 |
1969年 | 11篇 |
1966年 | 11篇 |
排序方式: 共有1843条查询结果,搜索用时 15 毫秒
71.
本论文研究了饲料加工的两个关键参数(调质温度和时间)对育肥猪颗粒饲料淀粉糊化度和维生素沉积的影响。日粮配方为含30%干酒糟及其可溶物的玉米-豆粕型基础日粮。整个试验中配方保持不变。本试验采用2×3双因子设计,调质温度分别为77℃和88℃,调质时间分别15秒、30秒和60秒。此外,本试验还设置一个对照组,对照组饲料不采用调质制粒工艺,而是采用粉料饲喂。因此,本试验共有7个处理组。采集调质后制粒前(热干粉)、制粒后冷却前(热制粒)、以及制粒冷却后(冷制粒)的样品,并分析这三种样品的总淀粉率、淀粉糊化 相似文献
72.
Perception of Teaching and Assessing Technical Proficiency in American College of Veterinary Surgeons Small Animal Surgery Residency Programs 下载免费PDF全文
73.
74.
75.
Serge MORAND Frédéric BORDES Hsuan‐Wien CHEN Julien CLAUDE Jean‐François COSSON Maxime GALAN Gábor Á CZIRJÁK Alex D GREENWOOD Alice LATINNE Johan MICHAUX Alexis RIBAS 《Integrative zoology》2015,10(5):409-423
We summarize the current knowledge on parasitism‐related invasion processes of the globally invasive Rattus lineages, originating from Asia, and how these invasions have impacted the local epidemiology of rodent‐borne diseases. Parasites play an important role in the invasion processes and successes of their hosts through multiple biological mechanisms such as “parasite release,” “immunocompetence advantage,” “biotic resistance” and “novel weapon.” Parasites may also greatly increase the impact of invasions by spillover of parasites and other pathogens, introduced with invasive hosts, into new hosts, potentially leading to novel emerging diseases. Another potential impact is the ability of the invader to amplify local parasites by spillback. In both cases, local fauna and humans may be exposed to new health risks, which may decrease biodiversity and potentially cause increases in human morbidity and mortality. Here we review the current knowledge on these processes and propose some research priorities. 相似文献
76.
77.
de Azevedo Pereira R Valencia-Jiménez A Magalhães CP Prates MV Melo JA de Lima LM de Sales MP Tempel Nakasu EY da Silva MC Grossi-de-Sá MF 《Journal of agricultural and food chemistry》2007,55(26):10714-10719
The coffee berry borer, Hypothenemus hampei (Ferrari), is an important devastating coffee pest worldwide. Both trypsin and chymotrypsin enzyme activities from H. hampei larval midgut can be inactivated by proteinaceous enzyme-inhibitors. A serine proteinase inhibitor belonging to the Bowman-Birk class was purified from a wild accession of Phaseolus coccineus L. seeds. The inhibitor (PcBBI1) is a cysteine-rich protein that is heat-stable at alkaline pH. MALDI-TOF/MS analysis showed that PcBBI1 occurs in seeds as a monomer (8689 Da) or dimer (17,378 Da). Using in vitro inhibition assays, it was found that PcBBI1 has a high inhibitory activity against H. hampei trypsin-like enzymes, bovine pancreatic chymotrypsin, and trypsin. According to this, PcBBI1 could be a promising tool to make genetically modified coffee with resistance to coffee berry borer. 相似文献
78.
Bryszewska MA Ambroziak W Langford NJ Baxter MJ Colyer A Lewis DJ 《Plant foods for human nutrition (Dordrecht, Netherlands)》2007,62(3):121-126
The potential of selenium-enriched rye/wheat sourdough bread as a route for supplementing dietary selenium intakes is reported.
In addition to their normal diets, 24 female volunteers (24 to 25 years old) were fed either selenium-enriched bread or non-enriched
bread each day (68.02 and 0.84 μg selenium day−1 respectively) for 4 weeks. The chemical form of the selenium in the bread had been characterised using HPLC-ICP-MS, which
showed that 42% of the extractable selenium was present as selenomethionine. Plasma selenium levels and plasma platelet glutathione
peroxidase (GPx1) activity were measured in the volunteers’ blood over a 6-week period. A statistically significant difference
(p = 0.001) was observed in the mean percentage change data, calculated from the plasma selenium level measurements for the
enriched and control group, over the duration of the study. A comparable difference was not observed for the platelet GPx1
activity (p = 0.756), over the same period. Two weeks after cessation of the feeding stage, i.e., at t = 6 weeks, the mean percentage change value for the selenium plasma levels in the enriched group was still significantly
elevated, suggesting that the absorbed selenium had been incorporated into the body’s selenium reserves, and was then being
slowly released back into the volunteers’ blood. 相似文献
79.
Cameon M. Ohmes Elizabeth G. Davis Laurie A. Beard Karie A. Vander Werf Alex W. Bianco Urs Giger 《The Canadian veterinary journal. La revue veterinaire canadienne》2014,55(2):147-151
Two Quarter horses with weight loss had glucosuria, euglycemia, and a mild metabolic acidosis suggesting a proximal renal tubular defect. Further testing revealed transient generalized aminoaciduria, lactic aciduria, and glucosuria, indicating Fanconi syndrome. Both horses recovered with supportive therapy. This is the first report of acquired Fanconi syndrome in horses. 相似文献
80.
Steffan Edward Octávio Oliveira Cíntia Carol de Melo Costa João Batista Freire de Souza Jr João Paulo Araújo Fernandes de Queiroz Alex Sandro Campos Maia Leonardo Lelis de Macedo Costa 《Tropical animal health and production》2014,46(8):1413-1417
The amount of short-wave solar radiation willingly tolerated by lactating Holstein cows on pasture was determined in an equatorial semi-arid environment. The study was carried out on a dairy farm located in Limoeiro do Norte, CE, northeastern Brazil. The observed behaviours were as follows: grazing, under the sun, under the shade, standing, lying, ruminating, idling and wallowing in the water. The behaviours were recorded using instantaneous scan sampling at regular intervals of 15 min from 0600 to 1800 hours over 5 days. On all sampling days, the meteorological variables, including local short-wave solar radiation (R S-W, W m?2), were recorded. The R S-W data were divided into five levels. The sun exposure was more frequent under low (100 %) and moderately low (97 %) levels, when R S-W remained below 500 W m?2. The grazing was more intense under low (100 %) and moderately low (93 %) levels. Above 500 W m?2, the grazing time significantly decreased (11 %). The cows avoided grazing under high (0 %) and very high (0 %) levels, when R S-W exceeded 700 W m?2. The ruminating behaviour was more frequent under high (33 %) and very high (37 %) levels, in which the highest averages of R S-W were recorded (815 and 958 W m?2, respectively). The standing posture was more frequent under low (100 %) and moderately low (97 %) levels. Therefore, the critical R S-W level that motivates cows to stop grazing and seek shade was in the interval between 500 and 700 W m?2. 相似文献