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   112篇
  免费   12篇
林业   1篇
综合类   3篇
农作物   11篇
畜牧兽医   107篇
园艺   2篇
  2021年   2篇
  2020年   3篇
  2019年   3篇
  2018年   4篇
  2017年   3篇
  2016年   3篇
  2015年   4篇
  2014年   3篇
  2013年   12篇
  2012年   5篇
  2011年   4篇
  2010年   13篇
  2009年   11篇
  2008年   1篇
  2007年   2篇
  2006年   1篇
  2005年   1篇
  2001年   2篇
  1999年   2篇
  1998年   5篇
  1997年   4篇
  1996年   5篇
  1995年   1篇
  1994年   3篇
  1993年   7篇
  1992年   4篇
  1991年   5篇
  1990年   3篇
  1989年   7篇
  1988年   1篇
排序方式: 共有124条查询结果,搜索用时 15 毫秒
81.
The aim of present study was to evaluate frozen canine semen with ACP-106 (Powder Coconut Water) using an in vitro sperm--oocyte interaction assay (SOIA). Ten ejaculates from five stud dogs were diluted in ACP-106 containing 20% egg yolk, submitted to cooling in a thermal box for 40 min and in a refrigerator for 30 min. After this period, a second dilution was performed using ACP-106 containing 20% egg yolk and 12% glycerol. Samples were thawed at 38 degrees C for 1 min. Post-thaw motility was evaluated by light microscopy and by using a computer aided semen analysis (CASA). Plasma membrane integrity and sperm morphology/acrosomal status were evaluated by fluorescent probes (C-FDA/PI) and Bengal Rose respectively. Moreover, frozen-thawed semen was analysed by a SOIA. Subjective post-thaw motility was 52.0 +/- 14.8% and it was significant higher than the total motility estimated by CASA (23.0 +/- 14.8%) because this system considered the egg yolk debris as immotile spermatozoa. Although normal sperm rate and acrosomal integrity evaluated by Bengal Rose stain was 89.6 +/- 3.1% and 94.3 +/- 3.1%, respectively, post-thaw percentage of intact plasma membrane was only 35.1 +/- 14.3%. Regarding SOIA, the percentage of interacted oocytes (bound, penetrated and bound and/or penetrated) was 75.3%. Using regression analysis, it was found significant relations between some CASA patterns and data for SOIA. In conclusion, the freezing-thawing procedure using ACP-106 was efficient for maintain the in vitro fertility potential of dog spermatozoa.  相似文献   
82.
Our aim was to evaluate the effects of fish oil feeding on sperm classical parameters, level of reactive oxygen spices (ROS), spermatozoa death incidence and in vitro fertilization (IVF) rate in rams. We randomly assigned nine rams, into two experimental groups (isoenergetic and isonitrogenous rations with constant level of vitamin E supplement): control (CTR; n = 5) and fish oil (FO; n = 4, 35 g/day/ram). Diets were fed for 70 days during the physiological breeding season. After a 21‐day dietary adaptation period, semen was collected weekly from each ram by an artificial vagina. Sperm classical parameters were determined by the computer‐assisted sperm analyzer system (CASA), and it was prepared for IVF process by swim‐up technique. These evaluations were performed during the first and last weeks of sampling. Intracellular ROS level and spermatozoa death incidence were detected by flow cytometry on a weekly basis after adaptation. Data were analysed with SPSS 15. The volume, concentration (3.6 and 2.7 × 109/ml) and sperm progressive motility (60 and 48%) were significantly improved in the FO group compared with the CTR (p < 0.05). A comparison of two‐cell stage embryos following IVF in the two groups showed a significantly higher fertilization rate in the FO group (56%) compared with the CTR (49%). Superoxide anion (O2?) rate was significantly lower (p < 0.05) at the third week of sampling in the FO. Although the H2O2 rate was numerically lower in the FO group compared with the CTR, this difference was not significant. In addition, apoptosis showed a significant difference in the third week of sampling (15 and 30% for FO and CTR, respectively; p < 0.05). Overall, adding fish oil to the ram diet not only improved sperm quality and IVF results, it also could reduce oxygen‐free radicals and the incidence of spermatozoa death.  相似文献   
83.
稻草床栽草菇培养料优质发酵方法研究   总被引:1,自引:0,他引:1  
简易发酵、一次发酵和二次发酵稻草培养料床栽草菇的试验结果表明,二次发酵法栽培的草菇生物学效率达16.3%,显著高于一次发酵及简易发酵,且能较好地控制病虫害的发生,提高了草菇的产量和质量。  相似文献   
84.
Thyroid disorders usually associated with lipid abnormalities. Overt hypothyroidism is a state with thyroid hormone deficiency. Sub clinical hypothyroidism is defined as condition, in which thyroid stimulating hormone concentration elevated when serum thyroid hormones are at normal levels. Whether sub-clinical hypothyroidism associated with lipid alteration, it is the main concept behind this study. Although, in this study, we found cases with normal thyroxin and elevated thyroid stimulating hormone are common, but whether the sub-clinical hypothyroidism finally converted to overt hypothyroidism are not universally accepted. The findings also indicated subjects with sub-clinical hypothyroidism usually are accompanied with dyslipidemia and in general the total cholesterol level is higher among sub-clinical hypothyroid patients, with eventual risk of arthrosclerosis. This study indicated that there is not a common findings to support the benefit of thyroxin therapy in sub-clinical hypothyroidism. It is concluded that it seems sub-clinical hypothyroidism is a common thyroid abnormality which can be diagnosed by the medical diagnostic laboratory through thyroid function test and it is mainly accompanied with lipid disorder.  相似文献   
85.
Iodine is in the crucial parts of two hormones of T4 and T3 produced by the thyroid glands which are essential for all the aspects of human metabolisms. It is demonstrated that iodine deficiency can be considered as sole cause of many thyroid abnormalities including mental disorders. Iodine deficiency of sufficient degree to cause hypothyroidism during fetus life and early infancy will be accompanied with brain abnormality possibly to the stage of mental retardation. The iodine deficiency among subjects in their early stage of childhood is not as severe as those in their fetus or infancy. In adult subjects the sever iodine deficiency can be also associated with mental disorders due to the direct side effects of hypothyroidism occurred by lack of iodine. The clinical manifestation of iodine deficiency show itself with psychological disorders in adult subjects. The status of iodine within blood can be evaluated through measurement of urinary iodine level and the low urinary concentration is an indicative of hypothyroidism. Mental retardation and brain damage due to iodine deficiency can be prevented if iodine supplementation prescribed duly on time.  相似文献   
86.
Thyroid stimulating hormone receptor (TSHR) is a vital thyrocyte membrane protein in the thyroid gland. Thyroid Stimulating Hormone (TSH) which is a pituitary hormone is the main stimulator of thyroid gland to produce thyroid hormones, it binds with high affinity to the TSHR through weak bonds including hydrophobic, ionic, hydrogen bonds and trigger the initial steps in thyroid gland stimulation to produce the related hormones. This study was carried out at department of biochemistry of Golestan university of medical sciences. All the related articles related to TSHR modification happened due to mutations and any other alterations which affect the level of TSH-TSHR complex were studied and the main points were extracted out of the pile of information and were organized as present review. TSH-TSHR is the initial and vital step of a long process of thyroid hormone production within the thyroid gland. Any alteration on the TSH-TSHR affinity which may happen due to the direct effect of TSHR modification eventually lead to the serious adverse effects of either hypothyroidism or hyperthyroidism if the TSH-TSHR level are suppressed or elevated, respectively. The prime cause of the thyroid disorders relay on the possible modification on the biochemical structure of TSHR with subsequent alteration on the level of TSH-TSHR complex. TSHR mutation accompanied by biochemical modification, unable it to bind properly to TSH. In some other conditions such mutation leave a TSHR with either of higher affinity towards to TSH or even TSHR which can be activated in the absence of TSH. The structural modification of TSHR and alteration in the level of TSH-TSHR in the thyroid gland eventually lead to thyroid disorders either of hypothyroidism or hyperthyroidism.  相似文献   
87.
Hypothyroidism is associated with mental and growth abnormality in children. The aim of this study was to determine the reference range of thyroid stimulating hormone (TSH). Thyroxin (T4) and triodothyronine (T3) of children in Northern Iran. The sample population for this study consists of subjects of 4 age groups up to 21 years. The subjects were selected randomly from people referred to Danesh Medical Diagnostic Laboratory in Gorgan Northern Iran. Thyroid hormone level were investigated with Radio immunoassay. The mean concentration for T4, T3, TSH for the sample population of 4 groups were as follow (113.5, 107.4, 102.9, 99.2 nmol L(-1)), (1.9, 1.7, 1.9, 1.6 nmol L(-1)) and (2.1,3.5, 2.9, 2.7 mIu L(-1)). The mean value of T3, TSH were higher for females but the mean value of T4 was slightly higher in males. The findings of this investigation indicated that there is an inverse age correlation in particular for T4 in all age groups. On the bases of the results from this study, we conclude that reference range, in all age groups and lower, upper limits of our reference range are not universally similar; therefore determination of reference range in each region is a critical need for clinical practice.  相似文献   
88.
New particle formation in a tropical marine boundary layer setting was characterized during NASA's Pacific Exploratory Mission-Tropics A program. It represents the clearest demonstration to date of aerosol nucleation and growth being linked to the natural marine sulfur cycle. This conclusion was based on real-time observations of dimethylsulfide, sulfur dioxide, sulfuric acid (gas), hydroxide, ozone, temperature, relative humidity, aerosol size and number distribution, and total aerosol surface area. Classic binary nucleation theory predicts no nucleation under the observed marine boundary layer conditions.  相似文献   
89.
Serological diagnosis of botulism in dairy cattle   总被引:1,自引:0,他引:1  
  相似文献   
90.
The flagellar beating of a spermatozoa's axoneme is caused by the varying activation and inactivation of dynein molecules. Dynein, axonemal, light chain 4 (DNAL 4 ) is a functional candidate gene for sperm motility as it encodes a small subunit of the dyneins. We resequenced the porcine DNAL 4 using three artificial insemination (AI ) boars each with high (>68%) or low (<60%) motility, and detected 23 SNP . These were then genotyped for 82 AI boars. Using spermatological records, significantly negative genetic correlations between ejaculate volume (VOL ) and the further spermatological parameters concentration (CONC ) (r  = ?.43), motility of undiluted semen (MOTUD ) (r  = ?.09), motility after 24 h (MOT 1) (r  = ?.17) and after 48 hr (MOT 2) (r  = ?.23) were estimated. Significantly positive correlations existed between CONC and MOT 1 (r  = .07) as well as MOT 2 (r  = .10), between MOTUD and MOT 1 (r  = .33), between MOTUD and MOT 2 (r  = .36), and finally between MOT 1 and MOT 2 (r  = .70). Significantly negatively correlated were all motility traits with the parameters abnormal acrosome (AA ) (MOTUD r  = ?.06; MOT 1 r  = ?.08, and MOT 2 r  = ?.1) and presence of cytoplasmic droplet (CD ) (MOTUD r  = ?.07; MOT 1 r  = ?.08; MOT 2 r  = ?.07). Association analyses (single marker regression model; SMR ) propose that SNP g.1007A>G, located in the second intron, reduces motility significantly (MOTUD ‐4.59%; MOT 1 ‐10.33%; MOT 2 ‐19.37%). According to the dominant‐recessive model (DRM ), genotype AA is always superior compared to genotypes AG and GG (i.e. MOTUD 67.67%, 64.16% and 53.91%; MOT 1 54.17%, 43.75% and 28.44%; MOT 2 44.12%, 24.91% and 4.97%). The average effect of gene substitution (g.1007A>G) on abnormal midpiece (AM ) was 0.71%, the genotypic values—as expressed by LS means—were 0.1 (AA ) and 0.81 (AG ).  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