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   415篇
  免费   14篇
  国内免费   1篇
林业   25篇
农学   4篇
基础科学   1篇
  120篇
综合类   17篇
农作物   37篇
水产渔业   16篇
畜牧兽医   181篇
园艺   10篇
植物保护   19篇
  2024年   2篇
  2023年   4篇
  2022年   9篇
  2021年   17篇
  2020年   12篇
  2019年   28篇
  2018年   18篇
  2017年   12篇
  2016年   17篇
  2015年   13篇
  2014年   17篇
  2013年   24篇
  2012年   32篇
  2011年   35篇
  2010年   14篇
  2009年   15篇
  2008年   31篇
  2007年   24篇
  2006年   23篇
  2005年   20篇
  2004年   26篇
  2003年   15篇
  2002年   15篇
  2001年   1篇
  1996年   1篇
  1993年   2篇
  1991年   1篇
  1988年   1篇
  1984年   1篇
排序方式: 共有430条查询结果,搜索用时 15 毫秒
101.
Bread wheat (BW) and durum wheat (DW) are both strongly affected by Septoria tritici blotch caused by the hemibiotrophic fungus Zymoseptoria tritici. However, only the BW-Z. tritici pathosystem has been well studied so far. Here, we compared compatible interactions between Z. tritici and both BW and DW species at the cytological, biochemical and molecular levels. Fungal infection process investigations showed close spore germination and leaf penetration features in both interactions, although differences in the patterns of these events were observed. During the necrotrophic phase, disease severity and sporulation levels were associated in both interactions with increases of the two cell-wall degrading enzyme activities endo-β-1,4-xylanase and endo-β-1,3-glucanase as well as protease. An analysis of plant defense responses during the first five days post inoculation revealed inductions of GLUC, Chi4, POX and PAL and a repression of LOX gene expressions in both wheat species, although differences in kinetics and levels of induction or repression were observed. In addition, peroxidase, catalase, glucanase, phenylalanine ammonia-lyase and lipoxygenase activities were induced in both wheat species, while only weak accumulations of hydrogen peroxide and polyphenols were detected at the fungal penetration sites. Our study revealed overall a similarity in Z. tritici infection process and triggered wheat defense pathways on both pathosystems.  相似文献   
102.
Five species of invasive Aedes mosquitoes have recently become established in Europe: Ae. albopictus, Ae. aegypti, Ae. japonicus japonicus, Ae. koreicus and Ae. atropalpus. These mosquitoes are a serious nuisance for people and are also competent vectors for several exotic pathogens such as dengue and chikungunya viruses. As they are a growing public health concern, methods to control these mosquitoes need to be implemented to reduce their biting and their potential for disease transmission. There is a crucial need to evaluate methods as part of an integrated invasive mosquito species control strategy in different European countries, taking into account local Aedes infestations and European regulations. This review presents the control methods available or in development against invasive Aedes mosquitoes, with a particular focus on those that can be implemented in Europe. These control methods are divided into five categories: environmental (source reduction), mechanical (trapping), biological (e.g. copepods, Bacillus thuringiensis var. israelensis, Wolbachia), chemical (insect growth regulators, pyrethroids) and genetic (sterile insect technique and genetically modified mosquitoes). We discuss the effectiveness, ecological impact, sustainability and stage of development of each control method. © 2015 Society of Chemical Industry  相似文献   
103.
104.
The present work describes the effect of nutritive level on horse carcass traits and on meat quality. Eighteen male Italian Heavy Draught Horse (IHDH) breed foals were employed in the study. Soon after foaling they were randomly subdivided into three groups according to three nutritive level classes: 150%, 180% and 200% of maintenance requirements. Live weight, hot carcass weight and dressing percentage of each animal were recorded. After slaughtering, meat samples were collected from Longissimus dorsi muscle. The right half carcass of each animal was then divided into cuts. Each one was subdivided into lean, fat and bones. Live weight, carcass weight and dressing percentage were not affected by nutritive level (P > 0.05). Horses fed with the lower nutritive level showed a higher incidence of lean and a lower incidence of fat (P < 0.01). Moreover, fatty acid profile was not affected by nutritive level (P > 0.05). Probably the tendency of IHDH foals to concentrate adipogenesis in the subcutaneous district could explain the lack of influence of nutritive level on meat quality parameters and its influence on carcass and cut composition, which tend to be richer in fat.  相似文献   
105.
Xanthomonas arboricola pv. juglandis is the causal agent of walnut blight, one of the most important and widespread diseases of Persian (English) walnut (Juglans regiaL.), causing severe damage to leaves, twigs and nuts. To investigate the genomic variability of X. arboricolapv. juglandis, 66 isolates obtained from different countries (England, France, Italy, The Netherlands, Romania, Spain, USA, and New Zealand) were analysed using the Amplified Fragment Length Polymorphism (AFLP) technique. EcoRI and MseI were used as restriction endonucleases. Primers with a core sequence including endonuclease recognition sites and a 3prime-terminal cytosine selective base for MseI primer, or no selective base for EcoRI primer, were used. Data were analysed by means of a multiple correspondence analysis. A total of 76 amplified polymorphic DNA fragments were used to compute relationships among isolates. The AFLP profiles of X. arboricola pv. juglandis isolates appeared to be reliably distinguishable from X. arboricola pv. pruni and X. arboricola pv. corylina, and from other Xanthomonas species, i.e. X. campestris pv. campestris, X. fragariae, X. hortorum, X. axonopodis pv. vesicatoria. Though this pathogen is associated with one single host genus, a high level of genomic diversity was found. This diversity might be partly explained by the geographic origin. Nevertheless, isolates with different patterns were collected within one country, and similar molecular patterns were found in isolates collected at different sites. However, genetic diversity might be influenced by exchanging vegetative material from different countries. Mixing of X. arboricola pv. juglandis isolates might have partly concealed the influence of the geographic location from which the bacteria were isolated.  相似文献   
106.
An enriched diet with antioxidants, such as vitamin E, vitamin C, β-carotene and phenolic compounds, has always been suggested to improve oxidative stress, preventing related diseases. In this respect, marine natural product (MNP), such as COX inhibitors, marine steroids, molecules interfering with factors involved in the modulation of gene expression (such as NF-κB), macrolides, many antioxidant agents, thermogenic substances and even substances that could help the immune system and that result in the protection of cartilage, have been recently gaining attention. The marine world represents a reserve of bioactive ingredients, with considerable potential as functional food. Substances, such as chitin, chitosan, n-3 oils, carotenoids, vitamins, minerals and bioactive peptides, can provide several health benefits, such as the reduction of cardiovascular diseases, anti-inflammatory and anticarcinogenic activities. In addition, new marine bioactive substances with potential anti-inflammatory, antioxidant and thermogenic capacity may provide health benefits and performance improvement, especially in those who practice physical activity, because of their increased free radical and Reacting Oxygen Species (ROS) production during exercise, and, particularly, in athletes. The aim of this review is to examine the potential pharmacological properties and application of many marine bioactive substances in sports.  相似文献   
107.
Phytochemical investigation of Helleborus niger L. (Ranunculaceae) leaf methanol extract allowed to isolate a phenolic glucoside derivative and two flavonoid glycosides characterized as phenyllactic acid 2-O-β-d-glucopyranoside (1), quercetin 3-O-2-(E-caffeoyl)-α-l-arabinopyranosyl-(1 → 2)-β-d-glucopyranoside-7-O-β-d-glucopyranoside (2), and kaempferol 3-O-α-l-arabinopyranosyl-(1 → 2)-β-d-galactopyranoside-7-O-β-d-glucopyranoside (3), respectively. Compounds 1 and 2 were isolated for the first time and their structural characterization was obtained on the basis of extensive NMR spectral studies.  相似文献   
108.

Objective

To retrospectively analyse handwritten preanaesthetic records for completeness at two veterinary referral institutions: a university veterinary teaching hospital and a private veterinary referral hospital. To evaluate if emergency records were less complete compared with non-emergency records. Animal or Animal Population Two hundred and fifty preanaesthetic records at each referral institution.

Materials and Methods

Handwritten preanaesthetic records were analysed for completeness. Data was described as complete or incomplete. In order to be classified as complete information had to be present, legible and correct. Sections of the preanaesthetic record analysed included the date, anaesthetist, clinician, presenting problem, procedure, time food withheld, temperature, pulse rate (PR), respiratory rate (fR), American Society of Anesthesiologists-Physical Status Classification (ASA-PSC), premedication drug name, premedication drug dose, premedication route of administration, premedication time, effect of premedication, induction drug name, induction drug dose, induction time, induction quality, maintenance anaesthetic agent, endotracheal tube (ET) diameter, anaesthetic breathing system and monitoring equipment.

Results

At both referral institutions 250 records were analysed. Completeness of data was generally poor, however, several differences did exist. Completion rates were generally higher at the university veterinary teaching hospital. A mix of structured and unstructured (requiring free text) data fields were poorly complete. Emergency records were significantly less complete with respect to: Time food withheld (p = 0.006) and Temperature (p = 0.0275).

Conclusions

Differences observed may be due to anaesthetic record design, anaesthetic caseload, case discussion, education or quality assurance programmes. Clinical relevance Increased emphasis on education and implementation of quality assurance programmes should be considered in order to improve completeness of preanaesthetic records.  相似文献   
109.
110.
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