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   95篇
  免费   24篇
  国内免费   1篇
农学   4篇
基础科学   2篇
  1篇
综合类   23篇
水产渔业   3篇
畜牧兽医   80篇
植物保护   7篇
  2023年   1篇
  2020年   4篇
  2019年   1篇
  2018年   8篇
  2017年   5篇
  2016年   6篇
  2015年   7篇
  2014年   1篇
  2013年   4篇
  2012年   3篇
  2011年   6篇
  2010年   7篇
  2009年   6篇
  2008年   5篇
  2007年   11篇
  2006年   2篇
  2005年   3篇
  2004年   1篇
  2003年   1篇
  2001年   3篇
  2000年   1篇
  1999年   1篇
  1998年   8篇
  1997年   5篇
  1996年   7篇
  1995年   2篇
  1994年   1篇
  1993年   3篇
  1992年   4篇
  1991年   1篇
  1990年   1篇
  1988年   1篇
排序方式: 共有120条查询结果,搜索用时 15 毫秒
81.
The aim of this study was to evaluate the effects of thyroxine administration on morphometric parameters, expression of vascular endothelial growth factor (VEGF) and vascularization in the uterus and placenta and reproductive parameters in gilts at 70 days of gestation. At 150 days of age, i.e., before first heat, 20 gilts were randomly divided into two experimental groups: treated (n = 10) and control (n = 10). The treated group received a daily dose of 400 μg of l ‐thyroxine (T4) in their diet until slaughter and the control group received only typical meals. Before artificial insemination, blood was collected to determine plasma total T4. The gilts were inseminated in the second oestrus and slaughtered at 70 days of gestation. The foetal thyroid follicular epithelium height, number, size and weight of foetuses; foetal myogenesis, corpora lutea number, embryonic mortality rate, uterine weight, placental weight and placental fluid volume were measured. Histomorphometric and immunohistochemical analysis of uterus and placenta were determined. The averages of all variables were compared by the Student’s t‐test. The gilts treated with thyroxine showed significant increase of plasma total T4. At 70 days of gestation, the heights of the trophoblastic epithelium, endometrial epithelium and endometrial gland epithelium were significantly higher in the group treated with T4. The expression of cytoplasmatic and nuclear VEGF in trophoblastic cells and the number of blood vessels per field in endometrial stroma were significantly higher in the gilts treated with T4. No other significant differences between groups were obtained with respect to other parameters (p > 0.05). We conclude that oral administration of T4 up to 70 days of pregnancy in gilts affects the morphometric parameters, the expression of placental VEGF and the uterine vascularization but does not affect reproductive parameters in gilts during early gestation.  相似文献   
82.
长沙市1997~2010年土地利用总体规划实施可持续利用评价   总被引:1,自引:0,他引:1  
以长沙市为例,运用生态足迹的方法对长沙市上轮土地利用总体规划的可持续利用情况进行了全面评价,为更好地修编新一轮土地利用总体规划提供依据,同时提出保持土地可持续利用应采取的措施。  相似文献   
83.
84.
AIM: To investigate, in a pilot study, a possible genetic component to type 2 diabetes mellitus (T2D) in Burmese cats in New Zealand by analysing pedigree data.

METHODS: Pedigrees were obtained for 305 Burmese cats living in New Zealand; diabetes was diagnosed in 19 of these due to presence of polyuria and polydipsia, persistent concentrations of glucose in plasma >16?mmol/L and glucosuria prior to insulin treatment. Pedigrees were also submitted for 16 cats with no clinical signs of T2D. The remaining 270 cats were unobserved relatives of these individuals. Inbreeding coefficients and heritability were calculated, and a single major locus model segregation analysis was conducted using pedigree analysis software.

RESULTS: Nineteen cats were diagnosed with T2D. Males (n = 14) and females (n = 5) were both affected, suggesting that the gene or genes causing diabetes are autosomal rather than sex-linked. Examination of the pedigree revealed few signs of fully penetrant dominant gene action: diabetes was ostensibly rarely seen in sequential generations and nearly always skipped at least one and often more generations; apparently unaffected offspring of apparently unaffected parents sometimes produced affected progeny. The mean relatedness of the affected animals within the core pedigree (16 diabetic cats) was 0.049, and mean inbreeding 0.033. Based on 100,000 permutations of the trait values, the expected relatedness of a random sample of 16 animals taken from the phenotyped animals would be 0.013 (SD 0.007) (permutation p = 0.0009). The observed inbreeding was also significant (permutation p= 0.02).

Heritability was estimated to be 9 (95% CI = 0–57)% assuming all animals with unknown status were unaffected. The best fitting genetic model was a major gene model with dominant expression with the risk allele frequency at 15% with 60% penetrance.

CONCLUSIONS: In this pilot study the increased inbreeding in the cases, lack of likely sampling bias, the increased frequency of T2D in Burmese, and small number of breed founders are consistent with the involvement of a major locus in diabetes in Burmese cats with a significant risk allele prevalence. However, low case numbers meant this could not be unambiguously confirmed. A genome-wide association study may be useful for investigating the genetic cause of T2D.  相似文献   
85.
家蚕新品种春华×秋实,经省级实验室联合鉴定,春期万蚕产茧量、万蚕茧层量、解舒丝长、解舒率比对照种菁松×皓月高7.6%、3.3%、11.6%、13.7%,净度高2.75分,出丝率略低,其余经济性状相仿.秋期饲养万蚕茧层量、解舒丝长、解舒率、出丝率比对照种秋丰×白玉提高6.9%、6.4%、16.3%、9.7%、4.1%,其他经济性状与对照相仿.两年农村生产鉴定结果,盒种产茧量比对照种高5.3%,产值高4.7%,50 kg桑产值高3.5%,茧丝长、解舒丝长、解舒率、干毛茧出丝率分别比对照种提高8.1%、13.0%、3.8%、2.9%.  相似文献   
86.
87.
克氏原螯虾原肌球蛋白的纯化及过敏原性分析   总被引:1,自引:0,他引:1  
以13份甲壳类动物过敏患者血清的Western—blotting分析,确定克氏原螯虾主要过敏原为36ku蛋白质.通过盐析、等电点沉淀及热处理等方法纯化该蛋白质,以兔抗拟穴青蟹原肌球蛋白(Tropo-myosin,TM)多克隆抗体的Western—blotting分析,确定该蛋白质为TM.同源性分析表明,克氏原螯虾TM与南美白对虾TM、拟穴青蟹的氨基酸序列相似性较高(〉90%).酶切位点预测显示,它分别有49个胰蛋白酶和6个胰凝乳蛋白酶的酶切位点.模拟胃肠液消化实验结果显示,纯化TM不易被胃蛋白酶降解,易于被胰蛋白酶和胰凝乳蛋白酶降解,进一步的Western—blotting和抑制性ELISA分析结果显示,其消化产物仍具有一定的免疫活性.采用蒸煮处理可降低TM的消化稳定性及免疫活性,且蒸煮处理时间越长,效果越显著.说明。TM为克氏原螯虾主要过敏原.与其他甲壳娄动物TM的序列相似件较高.  相似文献   
88.
The purpose of this study was to evaluate the effect of cooling ovarian tissue on pig pre-antral follicles. Ovaries were maintained in saline solution (0.9%) at 4 or 20 degrees C for 6, 12 or 18 h. After storage, pre-antral follicles were morphologically evaluated. While primordial follicles were not affected by the storage, the percentage of morphologically normal growing follicles was significantly reduced in ovarian tissue stored at 20 degrees C for 12 or 18 h. To test the viability of stored follicles, growing follicles isolated from ovaries stored at 4 degrees C for 18 h and at 20 degrees C for 6 h were cultured for 3 days. Follicles stored in either condition presented the same growth pattern in vitro as fresh follicles. We conclude that storage of pig ovaries at 4 degrees C for up to 18 h or at 20 degrees C for up to 6 h does not affect the morphology of growing follicles or their ability to grow in vitro.  相似文献   
89.
90.
SUMMARY Many of the nervous and muscular locomotor disorders that affect sheep throughout Australia are commonly referred to as ‘staggers’ syndromes. The range of clinical signs displayed by sheep suffering these disorders is sufficiently diverse to enable each syndrome to be graded into one of 5 progressive clinical groups. The first group, the limb paresis syndromes, includes the primary myopathies associated with the ingestion of Ixiolaena brevicompta, Malva parviflora, and Trachymene ochracea, as well as selenium and vitamin E disorders, Paroo virus staggers, congenital progressive muscular dystrophy, humpy back, hypocalcaemic muscle weakness, Tribulus terrestris staggers and tetanus . The second group is characterised by limb paresis with knuckling of the fetlocks, and includes the plant-associated toxicities of Romulea rosea, Stachys arvensis, Trachyandra divaricata, and Tribulus micrococcus, together with haloxon toxicity, enzootic ataxia (copper deficiency), and the probably genetic disorders of segmental axonopathy, neuroaxonal dystrophy, and degenerative thoracic myelopathy. Other locomotor disorders that fit more loosely into this group are listerial myelitis (post-dipping staggers), vitamin A deficiency, cervico-thoracic vertebral subluxation, Stypandra glauca toxicity, Ipomoea spp toxicity, ivermectin toxicity, and botulism . The third group, the falling syndromes, includes the probably genetic disorders of thalamic cerebellar neuropathy, cerebellar abiotrophy, and globoid cell leucodystrophy, together with Swainsona spp toxicity . The fourth group, the falling-with-tremors syndromes, includes the plant-associated toxicities of phalaris staggers, perennial rye grass staggers and nervous ergotism (Claviceps paspali) . The fifth group, the convulsive syndromes, includes the polioencephalomalacic entity nardoo fern (Marsilea drummondii) staggers, outbreaks of focal symmetrical encephalomalacia and the tunicaminyluracil toxicities known as annual ryegrass (Lolium rigidum) toxicity, annual beard grass (Polypogon monspeliensis) toxicity, blow away grass (Agrostis avenaceae) toxicity, and water damaged wheat (Triticum aestivum) toxicity . A dichotomous system is presented for the differential diagnosis of these groups of conditions .  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