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   383篇
  免费   20篇
  国内免费   1篇
林业   51篇
农学   9篇
基础科学   1篇
  89篇
综合类   34篇
农作物   23篇
水产渔业   16篇
畜牧兽医   131篇
园艺   17篇
植物保护   33篇
  2023年   1篇
  2022年   2篇
  2021年   9篇
  2020年   4篇
  2019年   12篇
  2018年   10篇
  2017年   11篇
  2016年   9篇
  2015年   8篇
  2014年   22篇
  2013年   13篇
  2012年   27篇
  2011年   33篇
  2010年   21篇
  2009年   24篇
  2008年   30篇
  2007年   32篇
  2006年   27篇
  2005年   23篇
  2004年   12篇
  2003年   15篇
  2002年   19篇
  2001年   2篇
  2000年   3篇
  1999年   5篇
  1998年   4篇
  1996年   2篇
  1995年   5篇
  1994年   3篇
  1993年   2篇
  1992年   1篇
  1991年   1篇
  1990年   1篇
  1989年   1篇
  1988年   2篇
  1985年   3篇
  1984年   1篇
  1983年   1篇
  1978年   2篇
  1955年   1篇
排序方式: 共有404条查询结果,搜索用时 15 毫秒
51.
Case history and presentationTwo non-human primates (Macaca fascicularis), weight 3.5 kg, enrolled in an experimental protocol received a 25 μg hour?1 transdermal fentanyl patch for postoperative analgesia. The following day both animals were clinically normal, but after a new induction of anaesthesia with ketamine, they developed severe and prolonged respiratory distress, profound coma and myosis.Management and follow-upAttempted reversal with naloxone was ineffective. After several hours of ventilation, both primates eventually died, 7 and 15 hours after ketamine injection, respectively. In both cases, the patch was discovered in the animal's cheek pouch. Subsequent fentanyl serum concentration measurements (8.29 and 14.80 μg L?1) confirmed fentanyl overdose.ConclusionsThis report of two fatal intoxications in non-human primates secondary to ingestion of a transdermal fentanyl patch demonstrates that this method of analgesia is inappropriate for non-human primates, because of their tendency to chew almost anything they can reach.  相似文献   
52.
Objective To determine whether predictable alveolar concentrations of sevoflurane are reliably produced in dogs when liquid sevoflurane is injected into closed circuit breathing systems, as calculated by Lowe's square‐root‐of‐time anaesthetic uptake model, and to confirm the validity of the model using soda lime and calcium hydroxide lime. Study design Prospective clinical study. Animals Eleven healthy dogs with a mean body mass of 34 ± 9 kg scheduled for pelvic limb orthopaedic surgery. Materials and methods Following pre‐anaesthetic medication, anaesthesia was induced with propofol and maintained with sevoflurane in a closed circle system. Epidural anaesthesia was performed with morphine and bupivacaine. Liquid sevoflurane was injected into the circuit by syringe, using dosages and time intervals derived from Lowe's square‐root‐of‐time anaesthetic uptake model. The target alveolar concentration chosen was 1.1 × MAC (2.6% end‐tidal sevoflurane). Either soda lime (group S; n = 6) or calcium hydroxide lime (Amsorb; group A; n = 5) were used for CO2 absorption. Sevoflurane concentration and the respiratory gas composition were measured with an infrared gas analyser. Results End‐tidal sevoflurane concentrations were close to the predicted value of 2.6% at 9 minutes (2.53 ± 0.1% group S; 2.60 ± 0.26% group A) and 16 minutes (2.55 ± 0.30 group S; 2.52 ± 0.28% group A) but declined thereafter to reach 50% (group S) and 64% (group A) of the predicted value at 121 minutes. There was a constant trend towards higher end‐tidal sevoflurane concentrations in group A but the difference was not statistically significant. Conclusions The square‐root‐of‐time model leads to significantly lower alveolar concentrations than expected, suggesting that the rate of sevoflurane uptake in dogs declines less rapidly than predicted. The use of Amsorb tends to reduce the deviation from predicted concentrations. Clinical relevance The model used in this study provided only an approximate guide to the volume of liquid sevoflurane required. Consequently, the definitive dose schedule must be based on measured anaesthetic concentrations and clinical monitoring.  相似文献   
53.
The labeling of products containing genetically modified organisms (GMO) is linked to their quantification since a threshold for the presence of fortuitous GMOs in food has been established. This threshold is calculated from a combination of two absolute quantification values: one for the specific GMO target and the second for an endogenous reference gene specific to the taxon. Thus, the development of reliable methods to quantify GMOs using endogenous reference genes in complex matrixes such as food and feed is needed. Plant identification can be difficult in the case of closely related taxa, which moreover are subject to introgression events. Based on the homology of beta-fructosidase sequences obtained from public databases, two couples of consensus primers were designed for the detection, quantification, and differentiation of four Solanaceae: potato (Solanum tuberosum), tomato (Solanum lycopersicum), pepper (Capsicum annuum), and eggplant (Solanum melongena). Sequence variability was studied first using lines and cultivars (intraspecies sequence variability), then using taxa involved in gene introgressions, and finally, using taxonomically close taxa (interspecies sequence variability). This study allowed us to design four highly specific TaqMan-MGB probes. A duplex real time PCR assay was developed for simultaneous quantification of tomato and potato. For eggplant and pepper, only simplex real time PCR tests were developed. The results demonstrated the high specificity and sensitivity of the assays. We therefore conclude that beta-fructosidase can be used as an endogenous reference gene for GMO analysis.  相似文献   
54.
55.
ObjectiveTo evaluate the effect of local anaesthesia of the mesovarium on end-tidal isoflurane (Fe′iso) concentration and vital parameters during canine ovariohysterectomy.Study designProspective, randomized, blinded study.AnimalsTwenty client-owned dogs undergoing elective ovariohysterectomy. Mean age 1.7 (±0.53, SD) years and mean body weight 21 kg (±5.9, SD).MethodsPre-medication was with intravenous acepromazine (0.02 mg kg−1) and methadone (0.1 mg kg−1). Anaesthesia was induced with propofol and maintained with isoflurane in oxygen. One group (n = 10) received local infiltration of the mesovarium with 0.5 mL lidocaine 2% and one group (n = 10) with 0.5 mL NaCl 0.9%. Heart (HR) and respiratory rates (fr), invasive mean arterial blood pressure (MAP) and Fe′isowere recorded. The Fe′iso was adjusted according to changes in HR, RR and MAP. Time points used for comparison were T1 (after induction of anaesthesia before surgery), T2 (after lidocaine infiltration of the mesovarium) and T3 (surgical manipulation of the ovaries). Data were analysed using a mixed model for repeated measurement anova and the Tukey adjustment. Results are presented as mean ± SD; p < 0.05 was considered significant.ResultsIn both groups, HR and fr remained stable at the three time points. Mean values ranged from 84 to 94 beats minute−1 and from 10 to 14 breaths minute−1. The Fe′iso was significantly lower at T3 compared to T1 and mean values ranged from 0.95% to 1.24%. The mean arterial blood pressure was significantly higher at T3 compared to T1 and mean values ranged from 58 to 96 mm Hg. At none of the time points were there significant differences between the two groups for HR, fr, MAP or Fe′iso.ConclusionNeither an isoflurane sparing effect nor a difference in autonomic response to surgery was demonstrated following local anaesthesia of the mesovarium.Clinical relevanceThere appeared to be minimal benefit from local anaesthesia of the mesovarium during this study.  相似文献   
56.
57.
58.
Pythium group F is a ubiquitous, though minor, pathogen in several soilless and soil cultures; investigations were carried out to analyze different regions of the DNA and better understand the nature of this group. Fourty-two isolates were obtained from a variety of plants (cucumber, lettuce, tomato) grown in soil or soilless cultures collected in various countries (Canada, Denmark, France, Norway, Sweden and United Kingdom). All Pythium group F isolates displayed amplified ITS1-5,8S-ITS2 ribosomal DNA region (rDNA) of similar length, whereas polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) revealed that, among the seven enzymes used, polymorphism was only identified with Hin6I. After cloning of ITS1-5,8S-ITS2 rDNA region from Pythium group F isolates that displayed restriction polymorphism patterns with Hin6I, comparisons of sequence and restriction mapping data showed a slight variation consisting in a single base change. Inter Simple Sequence Repeat (ISSR)-PCR method was also used to obtain data related to the entire genome and not only to a single DNA region. It identified repeated motifs in the genome of Pythium group F isolates. Two primers (CAC)5 and (CCA)5 detected polymorphism, and isolates were classified among 11 molecular clusters. The genetic diversity of this group was not correlated with the geographical locations or the host plants from which the isolates originated. Polymorphism of Pythium group F isolates pointed out by ISSR is discussed  相似文献   
59.
The ‘earthy’ and ‘muddy’ off‐flavours in pond‐reared fish are due to the presence of geosmin or 2‐methylisoborneol in the flesh of the fish. Similar off‐flavours have been reported in fish raised in recirculating aquaculture systems (RAS); however, little information is available regarding the cause of these off‐flavours. Our hypothesis was that earthy and muddy off‐flavour compounds, found previously in pond‐raised fish, are also responsible for off‐flavours in fish raised in RAS. In this preliminary study, we examined water, biofilms in RAS and fillets from cultured arctic charr known to have off‐flavours and requiring depuration using instrumental [solid‐phase microextraction procedure and gas chromatograph‐mass spectrometry (GC‐MS)] and human sensory analyses. Geosmin was present in the samples taken from the biofilter and on the side walls of the tanks. Two‐methylisoborneol was only found in low levels in the samples. The GC‐MS results indicated the presence of geosmin in the fillets (705 ng kg?1), but lower levels were found in the water (30.5 ng L?1). Sensory analyses also detected an earthy flavour (i.e., geosmin presence) in the fillets, and, therefore, it appears that geosmin is the main compound responsible for the off‐flavour in RAS. Further studies are being performed to identify the microorganisms responsible for geosmin production in RAS.  相似文献   
60.
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