全文获取类型
收费全文 | 1055篇 |
免费 | 59篇 |
专业分类
林业 | 45篇 |
农学 | 25篇 |
基础科学 | 8篇 |
178篇 | |
综合类 | 107篇 |
农作物 | 61篇 |
水产渔业 | 49篇 |
畜牧兽医 | 541篇 |
园艺 | 39篇 |
植物保护 | 61篇 |
出版年
2023年 | 4篇 |
2022年 | 5篇 |
2021年 | 19篇 |
2020年 | 18篇 |
2019年 | 25篇 |
2018年 | 15篇 |
2017年 | 12篇 |
2016年 | 21篇 |
2015年 | 22篇 |
2014年 | 22篇 |
2013年 | 53篇 |
2012年 | 54篇 |
2011年 | 63篇 |
2010年 | 34篇 |
2009年 | 42篇 |
2008年 | 73篇 |
2007年 | 63篇 |
2006年 | 82篇 |
2005年 | 77篇 |
2004年 | 68篇 |
2003年 | 65篇 |
2002年 | 73篇 |
2001年 | 16篇 |
2000年 | 5篇 |
1999年 | 13篇 |
1998年 | 7篇 |
1997年 | 11篇 |
1996年 | 15篇 |
1995年 | 6篇 |
1994年 | 10篇 |
1993年 | 6篇 |
1992年 | 5篇 |
1991年 | 6篇 |
1990年 | 5篇 |
1989年 | 8篇 |
1988年 | 5篇 |
1987年 | 7篇 |
1986年 | 5篇 |
1985年 | 5篇 |
1984年 | 4篇 |
1983年 | 7篇 |
1982年 | 4篇 |
1981年 | 4篇 |
1980年 | 3篇 |
1979年 | 4篇 |
1977年 | 5篇 |
1976年 | 7篇 |
1975年 | 6篇 |
1974年 | 5篇 |
1969年 | 3篇 |
排序方式: 共有1114条查询结果,搜索用时 0 毫秒
161.
Matthew Capitanio Dawn M Zimmerman Michael Douglass Terry Dew 《Journal of zoo and wildlife medicine》2008,39(2):270-273
A 16-yr-old, castrated male lion-tailed macaque (Macaca silenus) presented with acute bilateral pelvic limb paralysis. Cisternal and lumbar myelograms demonstrated right-sided spinal cord compression at T13-L1. During an extradural hemilaminectomy, chronically ruptured disk material was removed at T13-L1, with moderate venous dilatation observed cranially. The macaque fully recovered from clinical signs within 2 mo. 相似文献
162.
Iazbik MC Gómez Ochoa P Westendorf N Charske J Couto CG 《Journal of veterinary internal medicine / American College of Veterinary Internal Medicine》2007,21(6):1181-1184
BACKGROUND: Collection of 50 mL of blood (standard unit) in cats is a common procedure. There are several studies on the health status of donors, but to our knowledge there are no reports on the effects of blood collection on the feline donor. HYPOTHESIS: Collection of a standard unit of blood from cats does not significantly change arterial blood pressure (BP), mean arterial pressure (MAP), systolic arterial pressure (SAP), diastolic arterial pressure (DAP), PCV, and heart rate (HR) in healthy blood donor cats. ANIMALS: Twenty-six healthy blood donor cats (6 spayed females and 20 castrated males). METHODS: An oscillometric method was used to measure MAP, SAP, DAP, and to quantify HR before and after blood collection; PCV was obtained before and immediately after blood collection. RESULTS: Despite a significant decrease (P < .05) in all variables (ie, BP, PCV, HR) after blood collection, no adverse events were observed. CONCLUSIONS AND CLINICAL IMPORTANCE: The collection of a unit of blood for transfusion from healthy donor cats weighing more than 5 kg appears to be safe, but this procedure leads to a decrease in arterial BP, PCV, and HR. 相似文献
163.
Potato (Solanum tuberosum L.) cvs. AC Brador and Shepody grownin vitro exhibit plantlets with a short, rosette-type growth habit, and restricts multi plication rates. In contrast, Russet Burbank develops into plantlets with adequate internode lengthin vitro. Cool-white fluorescent lamps provided irradiation for wooden boxes fitted with yellow plexiglass filters. The resultant irradiation lacked wavelengths from 380 to 525 nm. A box fitted with clear plexiglass was the control. Internode length of plantlets was ca.1.0 cm for all three cultivars when grown in boxes with yellow filters, and was 0.5 cm when clear filters were used. The number of nodes, haulm area, stem length, haulm fresh and dry weight of cvs. AC Brador and Shepody were significantly greater in boxes with yellow filters. Potato cvs. AC Belmont, Eramosa, Hunter, Huron, Mirton Pearl, Raritan and York all have a short growth habitin vitro and stem length was increased by the use of a yellow filter. The incidence of intumescences or oedemas on leaves of potato plantletsin vitro was reduced from 60 to seven percent for AC Brador and from 70 to 10% for Shepody with the use of yellow filters. Blue-green light is therefore putatively involved in the occurrence of intumescences on potato tissuesin vitro. 相似文献
164.
165.
The veterinary profession, from acceptance to veterinary college to retirement, has experienced extensive organizational change in the past 3 decades. This paper is an attempt to understand the context and complexity of national workforce planning in veterinary medicine in Canada. It identifies the obvious practical and ethical considerations, exposing inherent problems in guiding the future of the profession. The discourse concludes there is a structural deficiency in veterinary education program capacity in Canada (practical fact) and Canadian youth may have increasingly difficult access to tertiary education (ethical concern). Adaptation, rather than planning, characterizes current practices in which migration of foreign-trained veterinarians mitigates the structural deficiency in training capacity. Due to the pervasive adoption of neo-liberal marketing principles in tertiary education, a nationally self-sufficient Canadian veterinary college infrastructure is an unlikely future possibility. Our current system, reliant on migration of internationally trained professionals, raises questions of global justice and individual rights. Strategic solutions require reflection on veterinary professional identity, broad discussion, and a commitment to a rigorous concept of professional responsibilities, global citizenship, and the public good. 相似文献
166.
167.
168.
Despite the high incidence of superficial digital flexor tendon (SDFT) injury in racehorses, the pathobiology of the condition is not clearly defined. The SDFT improves locomotor efficiency by storing elastic energy, but as a result it has low mechanical safety margins. As with the Achilles tendon in humans, rupture during athletic activity often follows accumulation of exercise and age-induced degenerative change that is not repaired by tenocytes. There is limited understanding of tenocyte biology and pathology, including responses to high mechanical strains and core temperatures during exercise. Unfortunately, much of the current information on SDFT pathology is derived from studies of collagenase-induced injury, which is a controversial model. Following rupture the overlapping phases of reactive inflammation, proliferation, remodelling and maturation do not necessarily reconstitute normal structure and function, resulting in long-term persistence of scar tissue and high re-injury rates. Tissue engineering approaches are likely to be applicable to SDFT lesions, but will require significant advances in cell biology research. 相似文献
169.
Clemens M. Altaner Elena N. Tokareva Janet C. T. Wong Adrian I. Hapca J. Paul McLean Michael C. Jarvis 《Wood Science and Technology》2009,43(3-4):279-290
As the severity of compression wood influences the mechanical and chemical properties of wood it is desirable to be able to measure compression wood severity. However, so far no satisfactory method has been reported in the literature. Here we describe how scanning FTIR micro-spectroscopy can be employed to achieve CW severity measurements on increment cores of Norway spruce (Picea abies (L. Karst.) and Sitka spruce (Picea sitchensis (Bong.) Carrière). Radial wood strips were converted into sawdust by a process that maintained their spatial orientation. Samples prepared in this way were scanned with an FTIR-microscope in reflective mode and from the spectra obtained a CW-indicator was calculated representing aromatic and carboxyl signals. This FTIR CW-indicator correlated well with alternative CW identification techniques (namely microfibril angle, transmitted light and immunolabelling of beta 1–4 galactan), which have been used to validate the method. Repeatability of the measurements was good and no systematic difference between spruce species was found. The achievable resolution of the measurements was of sub-mm order. The CW indicator described offers the opportunity to correlate CW severity with mechanical wood properties in spruce. 相似文献
170.
Onions are cured in order to form a complete, dry, outer skin which reduces water loss and suppresses incidence of disease, and can promote a darker skin finish. Currently in the UK, standard curing practises for onions involves heating at 28 °C for six weeks (65–75% RH), however, reducing curing temperatures may help to reduce energy usage. There is little empirical data on the effects of curing temperature on flavonol concentration in the skin of brown onions and on flavonol and anthocyanin concentration in the skin of red onions. Therefore, the aim of this study was to elucidate the compounds responsible for the change in onion skin colour when cured at different temperatures.Brown cvs. Sherpa and Wellington, and red onions cv. Red Baron, were cured at 20, 24 or 28 °C for six weeks. Replicated skin samples were analysed immediately after curing and after seven months cold storage at 1 ± 0.5 °C. Measurement of objective colour showed that skin of cvs. Sherpa and Wellington was darker and had a lower hue angle (H°) immediately after being cured at 28 °C compared to 20 °C. In contrast, skin of cv. Red Baron had a higher H° but no change in lightness (L*) when cured at 28 °C compared to 20 °C. Fructose, sucrose and glucose concentrations were analysed as they are thought to play a role in regulating the synthesis of flavonols and anthocyanins, both coloured compounds found in onion skin; however no significant correlations were found between colour data and sugar concentrations. Flavonols were measured in the skin of all cvs. and anthocyanins in the skin of cv. Red Baron. Quercetin glucoside and anthocyanin concentrations in the skin of onions cv. Red Baron immediately after curing were higher in those cured at 20 °C. Total flavonols and total anthocyanins were negatively correlated with H° in the skin of onions cv. Red Baron, but there was no similar correlation between total flavonols and H° for onion cvs. Sherpa and Wellington. This suggests that anthocyanins and flavonols may play a major role in varying skin colour of red onions cv. Red Baron cured at different temperatures; however, the difference between curing temperatures may not have been sufficient to represent a correlation between darkening of cvs. Sherpa and Wellington and flavonol concentration. Further investigation is therefore required to fully elucidate the compounds responsible for colour changes observed in brown onions. 相似文献