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   192篇
  免费   13篇
林业   5篇
基础科学   1篇
  28篇
综合类   4篇
农作物   4篇
水产渔业   9篇
畜牧兽医   138篇
园艺   12篇
植物保护   4篇
  2022年   2篇
  2021年   3篇
  2020年   1篇
  2019年   5篇
  2018年   4篇
  2017年   5篇
  2016年   4篇
  2015年   8篇
  2014年   7篇
  2013年   11篇
  2012年   15篇
  2011年   18篇
  2010年   5篇
  2009年   7篇
  2008年   15篇
  2007年   12篇
  2006年   14篇
  2005年   7篇
  2004年   9篇
  2003年   16篇
  2002年   4篇
  2001年   5篇
  2000年   6篇
  1999年   3篇
  1998年   1篇
  1997年   1篇
  1996年   2篇
  1995年   1篇
  1992年   2篇
  1991年   5篇
  1990年   3篇
  1989年   1篇
  1988年   1篇
  1983年   1篇
  1970年   1篇
排序方式: 共有205条查询结果,搜索用时 62 毫秒
101.
The purpose of this study was to determine steroid hormone concentration profiles in healthy intact and neutered male and female dogs. Seventeen intact female dogs, 20 intact male dogs, 30 spayed female dogs, and 30 castrated male dogs were used in this study. Serum samples were collected before and 1h after cosyntropin administration, and serum concentrations were determined for cortisol, progesterone, 17-OH progesterone (17-OHP), dehydroepiandrosterone sulfate (DHEAS), androstenedione, testosterone, and estradiol. Intact male dogs had greater concentrations of DHEAS, androstenedione, and testosterone. Intact female dogs had greater concentrations of progesterone. There was no significant difference in estradiol concentration among the four groups. Intact male dogs had lower concentrations of cortisol post-stimulation. DHEAS and testosterone did not increase in response to ACTH in intact males, and estradiol concentrations did not increase in response to ACTH in any group. Results from this study will enhance interpretation of suspected adrenal and/or gonadal disorders of dogs. Because estradiol concentrations were similar in all groups of dogs, measuring estradiol may not be a useful diagnostic test. Cortisol concentrations for intact male dogs with hyperadrenocorticism may be lower than those of female or neutered dogs.  相似文献   
102.
Objective: To compare incidence of postoperative complications and survival of horses that had surgery for enterolithiasis of the ascending (AC) or descending (DC) colon. Study design: Case series Animals: Horses (n=236) that had celiotomy for AC (n=97) or DC (n=139) enterolithiasis. Methods: Medical records (1999–2005) were reviewed for signalment, presenting clinical signs, surgical findings, postoperative complications, and short‐term survival until discharge. Information on performance and survival ≥1 year was obtained by telephone or mailed questionnaire. Results: Number of postoperative complications did not differ between groups (P=.76). The most frequently identified short‐term complications for all horses were incisional problems, gastric ulceration, ileus, diarrhea, fever, and anorexia. Horses with DC enteroliths had a significantly higher incidence of anorexia (P=.04) and fever (P=.01). The most common complications after hospital discharge were incisional problems, laminitis, weight loss, and colic. Although more DC horses were euthanatized intraoperatively (P=.02), no differences were detected for horses that survived until discharge (P=.18) or ≥1 year after discharge (P=.47). Conclusions: Number or type of postsurgical complications or survival after surgery was not influenced by enterolith location and horses have a favorable prognosis for long‐term survival after enterolith removal, regardless of site of obstruction in the colon. Clinical Relevance: Incidence of postoperative complications and survival are not affected by the site of enterolith obstruction in the colon.  相似文献   
103.
The automated analysis of total white blood cell count and white blood cell differentials is routine in research and clinical diagnosis in mammalian species. In contrast, in avian haematology these parameters are still estimated by conventional microscopic procedures due to technical difficulties associated with the morphological peculiarities of avian erythrocytes and thrombocytes. Both cell types are nucleated and fairly resistant to cell lysis, a prerequisite for automated leukocyte quantification and differentiation by commercial instruments. By using an anti-CD45 monoclonal antibody in combination with selected subset specific markers we have established a simple (no-lyse no-wash single-step one-tube) flow cytometry based technique for high precision chicken blood cell quantification. EDTA-blood samples are diluted, spiked with fluorescence beads and incubated with a mixture of fluorochrome conjugated chicken leukocyte specific antibodies. We demonstrate that total leukocyte numbers as well as thrombocyte, monocyte, T-cell, B-cell and heterophilic granulocyte numbers can be determined by flow cytometry in a single step without prior cell lysis, cell separation or cell washing steps. Importantly, we also show that blood samples can be fixed prior to cell staining which enables shipping of samples making the technology widely available. Comparison of this technique with conventional microscopy revealed superior precision. By comparing leukocyte differentials of two chicken populations and during immune system development after hatch we demonstrate that large sample numbers can be analysed within hours. This technique will help to overcome previous restrictions in immune status analysis in chickens in experimental systems, during vaccine testing and health status monitoring in chicken flocks. Advances in avian genomics should facilitate the development of appropriate tools for other avian species in the future which will make this technique broadly applicable.  相似文献   
104.
OBJECTIVE: To explore the relationship between subjective mood, folate status and homocysteine in healthy individuals. DESIGN: Subjective mood assessments were completed twice daily over the course of one week using the Positive and Negative Affect Scale (PANAS). The PANAS is a validated scale which considers mood state on two distinct continua, one reflecting positive mood and the other negative mood, each requiring response to 10 adjectives on a Likert scale. A blood sample was taken on one occasion at the start of the week during which subjective mood was assessed and analysed for red-blood-cell (RBC) folate, serum folate and plasma homocysteine concentrations. SUBJECTS: Male volunteers aged 19-47 years (n = 58) were recruited from local industries. RESULTS: High concentrations of RBC folate were associated with less variability (lower standard deviation) in negative mood (P = 0.023). Subjective mood, however, was not related to serum folate or homocysteine. CONCLUSIONS: This study appears to be the first to uncover an association between long-term folate status and subjective mood (employing the PANAS) in healthy males. More research is needed to further explore the relationship between nutritional status and mood.  相似文献   
105.
A double-blind study was conducted to compare gastric ulcer healing time in nontreated dogs with that in dogs treated with either cimetidine or omeprazole. Single ulcers were created in the gastric antrum by use of a suction biopsy capsule. Each dog was given 25 mg of aspirin/kg of body weight orally for 20 days after ulcer induction. Five control dogs were given aspirin only (no anti-ulcer medication) during the 20-day study. Six dogs were given cimetidine at dosage of 10 mg/kg orally every 8 hours, and 6 dogs were given omeprazole orally at dosage of 2 mumol/kg (0.7 mg/kg) once daily. All dogs were examined endoscopically on days 5, 10, 15, and 20 and were given a score for the size of the mechanically created ulcer and a score for the degree of aspirin-induced gastritis. All dogs were euthanatized on day 21, and gastric lesions were examined histologically. Significant differences were not evident in ulcer healing scores or degree of aspirin-induced gastritis among treated and nontreated dogs on days 5, 10, 15, and 20. However, aspirin-induced gastritis was less severe in dogs of the omeprazole group than in dogs of the cimetidine or control group on each day observations were made. The effect of omeprazole given once daily was comparable with that of cimetidine given every 8 hours in lessening aspirin-induced gastritis.  相似文献   
106.
OBJECTIVE: To determine accuracy and precision of a point-of-care hemoglobinometer for measuring hemoglobin concentration and estimating PCV in horses. DESIGN: Prospective trial. ANIMALS: 55 horses. PROCEDURE: Blood samples were obtained from 43 horses examined at a veterinary teaching hospital. Hemoglobin concentration was measured with the hemoglobinometer and by means of the standard cyanmethemoglobin method; PCV was measured by centrifugation. Blood samples were also obtained from 12 healthy horses, and PCV of aliquots of these samples was altered to approximately 5 to 80% by removing or adding plasma. Hemoglobin concentration and PCV were then measured. RESULTS: For samples from the clinic patients, hemoglobin concentrations obtained with the hemoglobinometer were less than concentrations obtained with the cyanmethemoglobin method; however, there was a linear relationship between concentrations obtained with the 2 methods. Breed, sex, body weight, and duration of sample storage did not significantly affect the difference between hemoglobin concentrations obtained with the 2 methods. There was a significant linear relationship between PCV and hemoglobinometer hemoglobin concentration (PCV = [2.83 x hemoglobin concentration] - 0.62). For samples from the healthy horses, a substantial negative bias was evident with the hemoglobinometer when hemoglobin concentration exceeded 16 g/dL. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that this hemoglobinometer is reasonably accurate and precise when used to measure hemoglobin concentration in blood samples from horses with a hemoglobin concentration < 16 g/dL.  相似文献   
107.
ABSTRACT Xylella fastidiosa causes Pierce's disease, a serious disease of grape, citrus variegated chlorosis, almond and oleander leaf scorches, and many other similar diseases. Although the complete genome sequences of several strains of this organism are now available, the function of most genes in this organism, especially those conferring virulence, is lacking. Attachment of X. fastidiosa to xylem vessels and insect vectors may be required for virulence and transmission; therefore, we disrupted fimA and fimF, genes encoding the major fimbrial protein FimA and a homolog of the fimbrial adhesin MrkD, to determine their role in the attachment process. Disruption of the fimA and fimF genes in Temecula1 and STL grape strains of X. fastidiosa was obtained by homologous recombination using plasmids pFAK and pFFK, respectively. These vectors contained a kanamycin resistance gene cloned into either the fimA or fimF genes of X. fastidiosa grape strains Temecula1 or STL. Efficiency of transformation was sufficiently high ( approximately 600 transformants per mug of pFFK DNA) to enable selection of rare recombination events. Polymerase chain reaction and Southern blot analyses of the mutants indicated that a double crossover event had occurred exclusively within the fimA and fimF genes, replacing the chromosomal gene with the disrupted gene and abolishing production of the corresponding proteins, FimA or FimF. Scanning electron microscopy revealed that fimbriae size and number, cell aggregation, and cell size were reduced for the FimA or FimF mutants of X. fastidiosa when compared with the parental strain. FimA or FimF mutants of X. fastidiosa remained pathogenic to grapevines, with bacterial populations slightly reduced compared with those of the wild-type X. fastidiosa cells. These mutants maintained their resistance to kanamycin in planta for at least 6 months in the greenhouse.  相似文献   
108.
Feil H  Feil WS  Purcell AH 《Phytopathology》2003,93(2):244-251
ABSTRACT The effects of date of inoculation on the development of Pierce's disease (PD) were evaluated in California grapevines during 1997 through 2000 at four locations. Some vines that had been inoculated either by using blue-green sharpshooters (Graphocephala atropunctata) as vectors or mechanically by needle puncture with the PD causal bacterium Xylella fastidiosa became infected during each month and at each location where infection was attempted. Vines inoculated on the earliest inoculation dates (April to May) developed more extensive and severe PD symptoms, and only 54% of these vines recovered from PD after the following winter, compared with vines that had been inoculated during June through August, of which 88% recovered from PD after the following winter. For the 1999 inoculations, the number of vines infected at a central California site (Parlier) was higher than the number of vines infected at a north coastal site (Hopland). For the best-fitting regression equation, percent recovery of vines infected with X. fastidiosa increased significantly with date of inoculation (r(2) = 0.737) at all sites excluding Hopland. The Hopland site had the highest percentage of vines that recovered from PD (100%). At most sites, only early infection (April and May) resulted in chronic disease unless the vines were inoculated at the bases instead of the distal tips of canes. Vines inoculated early in the growing season (April and May) have less chance to recover from Pierce's disease than vines inoculated later (July and August).  相似文献   
109.
110.
OBJECTIVE: To evaluate the tensile strength and wound morphology of the equine linea alba at intervals over 6 months after ventral median celiotomy. STUDY DESIGN: Linea alba tensile strength and wound morphology were determined at 2, 4, 8, 16, and 24 weeks postoperatively. Linea alba samples from 3 unoperated horses were used as controls. ANIMALS: Eighteen adult horses, weighing 400 to 500 kg, 4 to 15 years old. METHODS: Tensile strength and thickness of incised linea alba samples collected at 2, 4, 8, 16, and 24 weeks after ventral median celiotomy were compared with control linea alba samples. Additional samples were subjectively evaluated for wound morphology, notably collagen morphology. RESULTS: Control linea alba had a mean (+/-SEM) tensile strength of 484.9 +/- 58.3 N and was significantly (P < or = .05) stronger than at 2 weeks (87.7 +/- 61.4 N) after surgery. The tensile strength of 4-week (305.8 +/- 61.7 N), 8-week (465.4 +/- 56.5 N), and 16-week (477.8 +/- 57.2 N) samples were not significantly different from control linea alba. At 24 weeks, the tensile strength (721.0 +/- 57.9 N) was significantly stronger than control. The 2-, 4-, and 8-week samples were significantly thicker than controls, whereas the 16- and 24-week samples were not different from controls. On microscopy, control samples were characterized by dense mature collagen bundles. At 2 weeks, samples consisted primarily of granulation tissue, whereas at 4 weeks, samples had immature collagen fibers that were not formed into bundles, and at 8, 16, and 24 weeks, all samples had abundant mature collagen fibers formed into bundles. CONCLUSIONS: At 8 weeks, incised and sutured equine linea alba had a tensile strength comparable with non-incised linea alba and was characterized by mature collagen. CLINICAL RELEVANCE: Based on tensile strength and wound morphology, horses that have had an uncomplicated recovery after ventral median celiotomy should be able to return to controlled exercise as early as 60 days after surgery.  相似文献   
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