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   272篇
  免费   18篇
林业   19篇
农学   17篇
  58篇
综合类   9篇
农作物   12篇
水产渔业   23篇
畜牧兽医   131篇
园艺   2篇
植物保护   19篇
  2023年   5篇
  2022年   4篇
  2021年   11篇
  2020年   10篇
  2019年   13篇
  2018年   10篇
  2017年   16篇
  2016年   10篇
  2015年   9篇
  2014年   11篇
  2013年   13篇
  2012年   17篇
  2011年   23篇
  2010年   15篇
  2009年   9篇
  2008年   26篇
  2007年   18篇
  2006年   16篇
  2005年   7篇
  2004年   12篇
  2003年   6篇
  2002年   11篇
  2001年   2篇
  2000年   3篇
  1999年   1篇
  1997年   3篇
  1992年   2篇
  1990年   1篇
  1989年   2篇
  1988年   1篇
  1987年   1篇
  1985年   1篇
  1980年   1篇
排序方式: 共有290条查询结果,搜索用时 15 毫秒
1.
An attempt was made to evaluate gluten structural changes in refined and whole wheat pasta from hard white winter wheat to elucidate the impact of whole wheat components on the formation and structure of the gluten network in pasta. Attenuated total reflectance–FTIR spectroscopy was used to track gluten secondary structure through most of the major steps in pasta processing: raw material, mixing, drying, and cooking. Protein solubility, accessible thiols, and SDS‐PAGE data were also collected to provide additional information on the nature of protein interactions and network composition. Few secondary structural differences were observed between refined and whole wheat flours from hard white wheat. However, mixing induced a significant shift to β‐sheet structures in refined dough that was not equally matched by whole wheat dough. Drying under both high temperature, short time (HT) and low temperature, long time (LT) conditions resulted in a reversion to structural distributions similar to those for flour in both pastas. However, greater protein denaturation in HT samples was indicated by lower protein solubility also in the presence of denaturants and disulfide reducing agents. Cooking generated a substantial increase in β‐sheet structures for both pasta systems. This structure was greatest in refined and LT samples. Thiol accessibility data indicate the presence of a highly aggregated, compact gluten network in refined pasta, mostly driven by hydrophobic association. Conversely, the network in whole wheat pasta was more loosely associated and dependent on disulfide bonding, both of which fit well with the secondary structural data.  相似文献   
2.
3.
The presence of illicit drugs and their metabolites in surface waters has to be considered a new type of hazard, still unknown, for the aquatic ecosystem, due to the potent pharmacological activities of all the illicit drugs. Our research was therefore aimed at evaluating the impact of illicit drugs on the aquatic fauna, till now still undervalued. To this aim, we verified the ability of the European eel (Anguilla anguilla), a well-known biomonitor of environmental contamination, to bioaccumulate cocaine, one of the most abundant illicit drugs found in surface waters. Silver eels were exposed to a nominal cocaine concentration of 20?ng/l for 1?month; at the same time, control, carrier, and post-exposure recovery groups were made. Brains, gills, liver, kidney, muscle, gonads, spleen, digestive tract, and sections of dorsal skin were assayed by high-pressure liquid chromatography. Cocaine was found in the tissues of the treated eels and, at low concentrations, in almost all tissues of post-exposure recovery eels. These results indicate that cocaine is able to accumulate into the eel tissues; its presence suggests potential risks for eels since cocaine could affect their physiology and contribute to their decline, and for humans consuming contaminated fish.  相似文献   
4.
The cytochrome P450 (P450) superfamily represents a group of relevant enzymes in the field of drug metabolism and several exogenous or constitutional factors contribute to regulate its expression. Cattle represent an important source of animal-derived food-products and studies concerning the P450 expression are needed for the extrapolation of pharmacotoxicological data from one species to another and for the evaluation of the consumer's risk associated with the consumption of harmful residues found in foodstuffs. In the present study, possible breed-, gender- and species-differences in P4503A (the P450 subfamily more expressed in the human liver) expression were studied in vitro in Piedmontese (PDM) and Limousin (LIM) meat cattle breeds of both sexes and in domestic Ruminants (cattle, sheep and goats). Cytochrome P450 and P4503A contents as well as CYP3A-dependent drug metabolising enzymes (DME) were measured in liver microsomes. Significant lower levels of P450 (P < 0.001) and P4503A (P < 0.05) contents were observed in PDM vs. LIM of both sexes; the P4503A-dependent DME activities were significantly (P values ranging from 0.05 up to 0.001) higher in PDM cattle, particularly in males. A gender-effect in DME activities was noticed (P < 0.05) only in PDM male cattle. With regards to the species, the expression of both P4503A apoprotein and some of the related DME activities were more pronounced in sheep (P < 0.01 vs. cattle) and in goats (P < 0.05 vs. sheep; P < 0.01 vs. cattle) than in cattle. The significant differences in P4503A expression observed in LIM and PDM cattle are consistent with previously published data on strain- and breed-differences pointed out in rats and men. As far as a possible sex-effect is concerned, no clear-cut evidence is likely to be drawn. Finally, P4503A expression was more relevant in small ruminants.  相似文献   
5.
Veterinary public health (VPH) issues have received increased attention over the last few years as a result of the rising threat of emerging zoonoses (i.e., those due to globalized trade in animal and animal products and to changes in livestock production systems and the environment). The international dimension of VPH is gradually becoming recognized, and there is a growing need for veterinarians with experience in this field. In order to familiarize (future) veterinarians with the international dimension of VPH, the Department of Public Health and Food Safety of the Faculty of Veterinary Medicine, Utrecht University, has been organizing a course in Veterinary Public Health and Animal Production for over the last 10 years. This course has been intended for Dutch as well as foreign final-year veterinary students and recent veterinary graduates. By bringing together participants from different countries, the course reinforces the international dimension of the issues addressed through the exchange of experiences by the participants themselves. The present article provides information about this course on Veterinary Public Health (VPH): it discusses logistics, didactical approaches, the course program, and the use of information and communication technology (ICT). Special attention is given to the intercultural aspects of higher education, all of which play an important role in the efficient exchange of knowledge between lecturers and students. International courses are an important tool to enable participants to interact in a multicultural environment and address issues that demand international cooperation and a global public health focus.  相似文献   
6.
We evaluated stillbirth risk factors in two commercial swine farms of the Rio Grande do Sul State (south of Brazil). The study was conducted during 1 month in Farm A and during 2 months in Farm B, both during 1999. Data for all farrowings that occurred during the study period were recorded (101 for Farm A and 373 for Farm B), without interference in the farm management. In Farm A, 39% of all litters born during the period of interest had stillborn piglets and the stillborn risk for piglets was 12%. In Farm B, 25% of all litters had stillborn piglets whereas the stillborn risk was 2%. Variables considered as potential risk factors for stillbirths were: parity (1, 2–3, 4+); breed (purebred or crossbred); sow body-condition (normal or fat); use of oxytocin during parturition (yes or no); obstetric intervention through vaginal palpation (yes or no); farrowing duration (<4 or ≥4 h); mummified fetuses (yes or no); total litter size (<12 or ≥12 piglets); and litter birth weight (<11 or ≥11 kg). All stillborn piglets had their classification validated by necropsy. In multivariable logistic-regressions, the cases were the litters having at least one stillborn piglet. In Farm A, litters having at least 12 pigs and in which oxytocin was used during the parturition had 20.8-times-higher odds of stillborn occurrence. In Farm B, litters from sows having parity ≥4 had 2.2-times-higher odds of stillborn occurrence than litters from parity 2 to 3 females, litters having ≥12 pigs had 2.0-times-higher odds of a stillborn piglet than smaller litters and farrowings in which vaginal palpation was performed had 8.0-times-higher odds. Farrowing room management to minimize stillborn risk should target higher-parity females, large litters and optimization of practices of obstetric interventions.  相似文献   
7.
A 6-year-old, intact female, Labrador Retriever/Terrier cross was presented to the University Veterinary Hospital, University College Dublin with a 3-week history of therapy-resistant cervical pain and intermittent fever. Physical examination findings included marked cervical pain resulting in neck extension and vocalization. Examination of the CSF revealed mild pleocytosis (total nucleated cells = 0.009 x 10(9)/L, reference interval <0.005 x 10(9)/L). Cytocentrifuged preparations of the CSF were of low cellularity, containing predominantly macrophages and occasional small lymphocytes. Several small- to medium-sized fragments of a slightly granular, amorphous, eosinophilic substance were observed. The majority of mononuclear cells were located within this material, in small groups of 3-13 cells. The amorphous foamy material stained positive with Luxol fast blue, suggestive of myelin-like material. The dog was euthanized and postmortem examination revealed intervertebral disk protrusion between C2 and C3. Hematoxylin- and Luxol fast blue-stained histopathologic sections of brain and spinal cord revealed only mild hemorrhage. The extracellular material in the CSF of this dog may have been caused by myelin degeneration or leakage of phospholipids from damaged cells. Because no histologic evidence of demyelination was observed with the disk extrusion, the myelin-like material in this case was thought to be the product of phospholipid breakdown from damaged cellular membranes. Three cases of dogs with spinal cord disease and myelin-like material in the CSF have been reported previously. The clinical significance of this finding is still unknown.  相似文献   
8.
Veterinary Research Communications - Russo, V., Martelli, M., Mauro, A., Di Giacinto, O., Nardinocchi, D. and Berardinelli, P., 2007. Nuclear remodelling in growing oocytes of sheep. Veterinary...  相似文献   
9.
Biofilm-forming ability is increasingly being recognized as an important virulence factor in several Staphylococcus species. This study evaluated the biofilm-forming ability of sixty canine derived clinical isolates of S. pseudintermedius, using three phenotypic methods, microtiter plate test (MtP), Congo red agar method (CRA) and tube adherence test, and the presence and impact of biofilm-associated genes (icaA and icaD). The results showed that icaA and icaD genes were detected concomitantly in 55 (91.7%) of 60 isolates. A majority (88.3%) of the strains screened had matching results by the tube adherence test, MtP and PCR analysis. Better agreement (95%) was found between the PCR-based analysis and the CRA. Results of the icaA and icaD gene PCRs showed good agreement with CRA results, with a kappa of 0.7. Comparing the phenotypic methods, the statistical analysis showed that the agreement among the phenotypical tests using categorical data was generally good. Considering two classes (biofilm producer and biofilm non-producer), the percentage of matching results between the CRA method and the tube adherence test and between the CRA method and the MtP was 93.3%. A concordance of 100% was revealed between the MtP and the tube adherence test. The results indicate a high prevalence of the ica genes within S. pseudintermedius isolates, and their presence is associated with in vitro formation of a biofilm. A combination of phenotypic and genotypic tests is recommended for investigating biofilm formation in S. pseudintermedius.  相似文献   
10.
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