全文获取类型
收费全文 | 480篇 |
免费 | 45篇 |
专业分类
林业 | 11篇 |
农学 | 7篇 |
基础科学 | 3篇 |
56篇 | |
综合类 | 30篇 |
农作物 | 11篇 |
水产渔业 | 37篇 |
畜牧兽医 | 347篇 |
园艺 | 8篇 |
植物保护 | 15篇 |
出版年
2024年 | 3篇 |
2023年 | 18篇 |
2022年 | 12篇 |
2021年 | 22篇 |
2020年 | 14篇 |
2019年 | 23篇 |
2018年 | 21篇 |
2017年 | 21篇 |
2016年 | 12篇 |
2015年 | 16篇 |
2014年 | 27篇 |
2013年 | 13篇 |
2012年 | 31篇 |
2011年 | 34篇 |
2010年 | 18篇 |
2009年 | 13篇 |
2008年 | 24篇 |
2007年 | 20篇 |
2006年 | 20篇 |
2005年 | 37篇 |
2004年 | 33篇 |
2003年 | 35篇 |
2002年 | 39篇 |
2001年 | 4篇 |
2000年 | 2篇 |
1998年 | 1篇 |
1997年 | 3篇 |
1996年 | 3篇 |
1995年 | 1篇 |
1994年 | 2篇 |
1993年 | 1篇 |
1983年 | 1篇 |
1888年 | 1篇 |
排序方式: 共有525条查询结果,搜索用时 15 毫秒
101.
Sue Aenishaenslin Kate Convery Basil Gua Mia Spain Lee Tunstall 《Small-Scale Forestry》2007,6(2):141-155
Private native forests in Australia perform a dual production and conservation role, providing an important source of timber,
and complementing formal conservation reserves. A comparison of policies for private native forests in New South Wales, Queensland,
Victoria and Tasmania illustrates the scope for timber harvesting, the provision for environmental values, and initiatives
for responsible and sustainable forest management. The sustainable management of Australia’s forests requires initiatives
by both government and landowners to accommodate changes in community attitudes, new management strategies, integrated catchment
management principles and both commercial and non-commercial opportunities for forest use. Of all of the Australian states,
New South Wales has the most restrictive laws in terms of forest management and harvesting. Queensland and Victorian legislation
have a more commercial focus, while Tasmania has a balance of both environmental and commercial objectives. The duty of care
for private native forests is a responsibility that falls to the landholder, and while this should be enforced by legislation,
the private provision of community benefits requires both recognition and reward. The presence or absence of incentives potentially
determines the effectiveness of forest codes of practice. 相似文献
102.
OBJECTIVE: To compare therapeutic feeding programme coverage for severely malnourished children achieved by a community-based therapeutic care (CTC) programme and a therapeutic feeding centre (TFC) programme operating in neighbouring districts in Malawi. DESIGN: Two surveys were implemented simultaneously one in each of the two programme areas. Each survey used a stratified design with strata defined using the centric systematic area sample method. Thirty 100 km2 quadrats were sampled. The community or communities located closest to the centre of each quadrat were sampled using a case-finding approach. Cases were defined as children aged under 5 years with = 70% of the weight-for-height median or bilateral pitting oedema. Receipt of treatment was ascertained by the child's presence in a therapeutic feeding programme or by documentary evidence. Coverage in each quadrat was estimated in two ways, a period estimate that provides an estimation of coverage for the recent period preceding the survey and a point estimate that provides an estimation of coverage at the exact point in time of the survey. RESULTS: Overall the period coverage was 24.55% (95% confidence interval (CI) = 17.8-31.4%) in the TFC programme and 73.64% (95% CI = 66.0-81.3%) in the CTC programme. The point coverage was 20.04% (95% CI = 13.8-26.3%) in the TFC programme and 59.95% (95% CI = 51.4-68.5%) in the CTC programme. CONCLUSIONS: In this context, CTC gave substantially higher programme coverage than a TFC programme. Given effective treatment, this enabled higher impact of CTC on severe malnutrition in this population. 相似文献
103.
104.
Objective: To determine whether in healthy horses and those with colic, exposure of peritoneal fluid to room air affects values obtained on biochemical analysis. Study Design: Prospective study. Animals: Adult horses with a primary complaint of acute abdominal pain (n=29) and 12 healthy horses. Methods: Peritoneal fluid was aseptically collected under aerobic and anaerobic conditions. After collection, pH, PCO2, PO2, HCO3?, Na+, ionized Ca2+, K+, lactate, and glucose were immediately measured using a commercial blood gas analyzer. Biochemical variables were compared between aerobically and anaerobically obtained samples using a paired t‐test. Results: In healthy horses, peritoneal fluid samples collected under anaerobic conditions had higher PCO2 and ionized Ca2+ and lower PO2, HCO3?, and pH compared with samples exposed to air. No differences were observed for K+, Na+, glucose, and lactate. In horses with colic, samples collected anaerobically had higher PCO2, ionized Ca2+, Na+, and glucose and lower PO2, HCO3?, and pH value compared with samples exposed to air. No differences were observed for K+ and lactate. Conclusion: Exposure of peritoneal fluid to room air had a significant effect on pH, PCO2, PO2, and variables associated or dependent on changes in pH such as HCO3? and ionized Ca2+. Interpretation of biochemical analysis of peritoneal fluid may be influenced by sample collection method. 相似文献
105.
106.
Hill KE Scott-Moncrieff JC Koshko MA Glickman LT Glickman NW Nelson RW Blevins WE Oliver JW 《Journal of the American Veterinary Medical Association》2005,226(4):556-561
OBJECTIVE: To evaluate adrenal sex hormone concentrations in response to ACTH stimulation in healthy dogs, dogs with adrenal tumors, and dogs with pituitary-dependent hyperadrenocorticism (PDH). DESIGN: Prospective study. ANIMALS: 11 healthy control dogs, 9 dogs with adrenal-dependent hyperadrenocorticism (adenocarcinoma [ACA] or other tumor); 11 dogs with PDH, and 6 dogs with noncortisol-secreting adrenal tumors (ATs). PROCEDURE: Hyperadrenocorticism was diagnosed on the basis of clinical signs; physical examination findings; and results of ACTH stimulation test, low-dose dexamethasone suppression test, or both. Dogs with noncortisol-secreting ATs did not have hyperadrenocorticism but had ultrasonographic evidence of an AT. Concentrations of cortisol, androstenedione, estradiol, progesterone, testosterone, and 17-hydroxyprogesterone were measured before and 1 hour after i.m. administration of 0.25 mg of synthetic ACTH. RESULTS: All dogs with ACA, 10 dogs with PDH, and 4 dogs with ATs had 1 or more sex hormone concentrations greater than the reference range after ACTH stimulation. The absolute difference for progesterone, 17-hydroxyprogesterone, and testosterone concentrations (value obtained after ACTH administration minus value obtained before ACTH administration) was significantly greater for dogs with ACA, compared with the other 3 groups. The absolute difference for androstenedione was significantly greater for dogs with ACA, compared with dogs with AT and healthy control dogs. CONCLUSIONS AND CLINICAL RELEVANCE: Dogs with ACA secrete increased concentrations of adrenal sex hormones, compared with dogs with PDH, noncortisol-secreting ATs, and healthy dogs. Dogs with noncortisol-secreting ATs also have increased concentrations of sex hormones. There is great interdog variability in sex hormone concentrations in dogs with ACA after stimulation with ACTH. 相似文献
107.
108.
109.
110.