首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   2125篇
  免费   126篇
林业   193篇
农学   70篇
基础科学   21篇
  600篇
综合类   81篇
农作物   122篇
水产渔业   279篇
畜牧兽医   675篇
园艺   61篇
植物保护   149篇
  2024年   5篇
  2023年   25篇
  2022年   46篇
  2021年   95篇
  2020年   72篇
  2019年   100篇
  2018年   71篇
  2017年   80篇
  2016年   85篇
  2015年   64篇
  2014年   103篇
  2013年   128篇
  2012年   184篇
  2011年   176篇
  2010年   101篇
  2009年   97篇
  2008年   138篇
  2007年   132篇
  2006年   108篇
  2005年   115篇
  2004年   96篇
  2003年   79篇
  2002年   65篇
  2001年   14篇
  2000年   11篇
  1999年   7篇
  1998年   7篇
  1997年   9篇
  1996年   5篇
  1995年   4篇
  1994年   4篇
  1993年   4篇
  1992年   3篇
  1991年   2篇
  1990年   2篇
  1989年   3篇
  1988年   2篇
  1986年   2篇
  1983年   1篇
  1978年   1篇
  1977年   1篇
  1963年   1篇
  1954年   1篇
  1944年   1篇
  1939年   1篇
排序方式: 共有2251条查询结果,搜索用时 15 毫秒
991.
This report describes a case of postanesthetic brachial triceps myonecrosis affecting only the left forelimb of a horse. A fatal unilateral postanesthetic myonecrosis has not been previously reported in the horse. This article describes the factors in the horse’s history, the anesthetic protocol, and the treatment that may have led to this condition.  相似文献   
992.
During the first 3 months of 2006, a study was performed on four dairy cattle herds with a history of clinical paratuberculosis, to evaluate different enzyme-linked immunosorbent assays (ELISAs). Serum samples obtained from 326 animals were analysed using four ELISAs to detect antibodies to Mycobacterium avium subsp. paratuberculosis (MAP). Kappa (kappa) concordance coefficients in pairwise comparisons of the ELISA outcomes ranged up to 0.22 (linear kappa) and 0.25 (quadratic kappa). When the borderline positives obtained were considered as negatives, kappa values remained low (kappa up to 0.19). Having performed the serological tests, faecal samples were then obtained from 55 animals (including all animals testing positive in two or more ELISAs) from the same herds. Faecal culture and faecal polymerase chain reaction (PCR) for the detection of MAP were negative in all cases. The results indicate that neither the currently available serum ELISAs nor faecal culture and PCR are effective for the early detection of MAP in dairy cattle.  相似文献   
993.
In this report, we describe a case of retrobulbar abscessation in a dog that was initially diagnosed as masticatory myositis and treated with immunosuppressive doses of corticosteroids. Secondary bacterial infection of the central nervous system (CNS) occurred and was definitively diagnosed by the analysis and culture of the cerebrospinal fluid. This is the first time that retrobulbar infection has been definitively shown to result in secondary bacterial infection of the CNS in the dog and highlights the importance of ruling out infectious causes of retrobulbar disease before assuming and treating for an immune-mediated etiology.  相似文献   
994.
995.
996.
997.
Cellular membrane fusion is thought to proceed through intermediates including docking of apposed lipid bilayers, merging of proximal leaflets to form a hemifusion diaphragm, and fusion pore opening. A membrane-bridging four-helix complex of soluble N-ethylmaleimide-sensitive factor attachment protein receptors (SNAREs) mediates fusion. However, how assembly of the SNARE complex generates docking and other fusion intermediates is unknown. Using a cell-free reaction, we identified intermediates visually and then arrested the SNARE fusion machinery when fusion was about to begin. Partial and directional assembly of SNAREs tightly docked bilayers, but efficient fusion and an extended form of hemifusion required assembly beyond the core complex to the membrane-connecting linkers. We propose that straining of lipids at the edges of an extended docking zone initiates fusion.  相似文献   
998.
The minimal processing industry for fruit and vegetables needs appropriate selection of raw materials and operation of improved sustainable strategies for reducing losses and providing high quality and safe commodities. The most important target for keeping overall quality of these commodities is a decrease in microbial spoilage flora as these cause both decay and safety problems. Every step in the production chain will influence microbial load and the implementation of an accurate disinfection program should be the main concern of commercial processing. The only step that reduces microbial load throughout the production chain is washing disinfection, and the keys are proper handling and optimizing existing techniques or a combination of them. Chlorine is a common efficient sanitation agent but there is the risk of undesirable by-products upon reaction with organic matter and this may lead to new regulatory restrictions in the future. Moreover, its efficacy is poor for some products. Consequently the minimal processing industry wants safer alternatives. Several antimicrobial washing solutions, O3, UV–C radiation, intense light pulses, super high O2, N2O and noble gases, alone or in combination, are presently considered promising treatments. However, change from use of conventional to innovative sanitizers requires knowledge of the benefits and restrictions as well as a practical outlook. This review addresses some recent results obtained with these eco-innovative sanitizers on fresh-cut plant commodities.  相似文献   
999.
This study was conducted to evaluate the efficacy of β-glucan and selenium supplements to the diet on increasing survival of hybrid striped bass Morone chrysops X M. saxatilis exposed to Streptococcus iniae. A 2 × 2 × 2 factorial design was employed by including purified casein/gelatin-based diets and practical menhaden fish meal-based diets with supplement! of either β-glucan from barley at 0 and 0.1 % of diet or sodium selenite at 0 or 0.2 mg/kg diet or a combination of these supplements. All diets were formulated to meet the nutritional needs of hybrid striped bass with the exception of selenium. The purified and practical basal diets contained 0.03 and 1.03 mg Se/kg, respectively, and the diets supplemented with sodium selenite had an additional 0.07 mg Se/kg on average. Juvenile hybrid striped bass initially averaging 2.44 ± 0.17 g/fish were fed the eight experimental diets in triplicate 110-L recirculating aquaria for 6 wk, after which they were immersed in a bath of S. iniae at 6.2 × 106 CFU/mL for 2 h and monitored for 21 d. Weighi gain and feed efficiency were significantly (P < 0.05) affected by diet type and selenium supplementation, with fish fed practical diets and those supplemented with selenium having the greatest values. Supplementation of β-glucan to the purified or practical type diets did not significantly affect survival of fish after experimental infection. The most notable difference (P < 0.0001) was in the comparison of diet type; the survival rate of fish fed the practical diets was 75% compared to 35% for those fed the purified diets. Dietary supplementation of β-glucan did not enhance disease resistance in the present study. Fish fed menhaden fish meal-based diets were significantly more resistant to 5. iniae in comparison to the those fed the purified diets. Thus, nutritional influences on disease resistance of hybrid striped bass were evident in this study and warrant further investigation.  相似文献   
1000.
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号