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   499篇
  免费   63篇
  国内免费   64篇
农学   8篇
  1篇
综合类   120篇
农作物   4篇
水产渔业   80篇
畜牧兽医   413篇
  2023年   9篇
  2022年   9篇
  2021年   29篇
  2020年   21篇
  2019年   25篇
  2018年   15篇
  2017年   26篇
  2016年   24篇
  2015年   30篇
  2014年   35篇
  2013年   33篇
  2012年   40篇
  2011年   36篇
  2010年   41篇
  2009年   39篇
  2008年   30篇
  2007年   31篇
  2006年   27篇
  2005年   23篇
  2004年   14篇
  2003年   13篇
  2002年   13篇
  2001年   15篇
  2000年   9篇
  1999年   8篇
  1998年   6篇
  1997年   4篇
  1996年   2篇
  1993年   3篇
  1992年   7篇
  1991年   2篇
  1990年   1篇
  1989年   1篇
  1988年   4篇
  1987年   1篇
排序方式: 共有626条查询结果,搜索用时 15 毫秒
1.
This report presents a new case of mucormycosis encountered in penguin characterized by morphological variation of hyphae and presence of sporangia with numerous sporangiospores. A 4.5-year-old Magellanic penguin (Spheniscus magellanicus) died after exhibiting anorexia, poor nutritional condition and dyspnea. Multiple nodular lesions were observed in the thoracic and abdominal regions. Histopathologically, hyphae of various sizes were seen in the lungs, air sac and nodular lesions. Myriad sporangiospores and several sporangia were observed in/around the bronchi or parabronchi. The very narrow and short hyphae in the nodules were not consistent with the characteristics of Mucorales. However, for most hyphae, including those in the nodules, sporangiospores and sporangia, immunohistochemistry revealed Mucorales-positive reactions. In addition, these fungi were identified as Rhizomucor pusillus by gene analysis.  相似文献   
2.
This study investigated the correlation between KIT gene expression determined by immunohistochemistry and real‐time polymerase chain reaction (RT‐PCR) and the rate of tumour recurrence and tumour‐related deaths in dogs affected with mast cell tumour (MCT). Kaplan–Meier curves were constructed to compare tumour recurrence and tumour‐related death between patients. The log‐rank test was used to check for significant differences between curves. KIT‐I, KIT‐II and KIT‐III staining patterns were observed in 9 (11.11%), 50 (61.73%) and 22 (27.16%) tumours, respectively. Tumour recurrence rates and tumour‐related deaths were not associated with KIT staining patterns (P = 0278, P > 0.05), KIT (P = 0.289, P > 0.05) or KIT ligand (P = 0.106, P > 0.05) gene expression. Despite the lack of association between KIT staining pattern and patient survival time, the results suggest a correlation between aberrant KIT localization and increased proliferative activity of MCTs. RT‐PCR seems to be a sensible method for quantitative detection of KIT gene expression in canine MCT, although expressions levels are not correlated with prognosis.  相似文献   
3.
We examined whether mutation of the platelet‐derived growth factor receptor protein tyrosine kinase (PDGFR)‐α and PDGFR‐β genes contributes to their overexpression in canine vascular tumours. Genomic sequences of trans‐ or juxtamembrane regions of PDGFR‐α and PDGFR‐β were analysed with immunohistochemical staining and polymerase chain reaction‐direct sequencing using DNA from paraffin‐embedded neoplastic tissues of 27 hemangiosarcomas (HSAs) and 20 hemangiomas (HAs). Immunohistochemically, 75% of the HA cases were positive for PDGFR‐α and almost most of the HA cases were negative for PDGFR‐β. Of the HSA cases, 55.6% were negative for PDGFR‐α and 63% were strongly positive for PDGFR‐β. Among the HA cases, 1 missense mutation was detected in PDGFR‐α exon 18 and 1 in PDGFR‐β exon 17. Two HSA cases had missense mutations in exon 14 and 1 in exon 17 of PDGFR‐β. Thus, genomic mutation of trans‐ or juxtamembrane regions of PDGFRs was not the main mechanism driving the activation of receptors in HSA and HA.  相似文献   
4.
5.
6.
A 2-year-old Standardbred gelding was referred for a mass on the palmaromedial right front pastern which was accompanied by progressively worsening lameness. The mass was firm to palpation and covered by normal skin. Ultrasonographically, a smooth encapsulated mass was present, medial to the flexor tendons and palmar to the neurovascular bundle. Because of a poor prognosis for future athletic performance without surgical or chemotherapeutic intervention and economic constraints preventing further diagnostics and treatment, the horse was euthanised. Post-mortem magnetic resonance imaging, histopathology and immunohistochemistry revealed the mass to be a perivascular wall tumour, the first record of such a neoplasia in the horse.  相似文献   
7.
为比较2、35日龄滩羊皮肤毛囊的发育特点与血管内皮生长因子(vascular endothelial growth factor,VEGF)和血管内皮生长因子受体2(vascular endothelial growth factor receptor 2,VEGFR2)的分布特征,探究出生后滩羊被毛生长发育的变化特点,试验应用常规HE染色及改良Masson胶原纤维染色、Gomori银氨法染色、磷钨酸染色等特殊染色观察2与35日龄滩羊皮肤组织结构特点;应用免疫组织化学法结合免疫荧光染色法观察VEGF及VEGFR2在2与35日龄滩羊皮肤组织中的分布定位,并用IPP图像分析软件进行定量分析。结果显示:与2日龄滩羊皮肤组织比较,35日龄滩羊表皮与真皮间界限更加清晰,毛囊结构发育完整;毛囊密度显著降低(P<0.05);胶原纤维与弹性纤维含量增加,形成网格状分布。免疫组化及免疫荧光结果显示,VEGF及VEGFR2在滩羊皮肤表皮及毛囊外根鞘、皮脂腺上均有表达。统计表明,VEGF及VEGFR2在2日龄滩羊皮肤组织中的表达量均显著高于35日龄(P<0.05)。综合上述结果,滩羊毛囊发育过程中,胶原纤维和弹性纤维增加明显;VEGF与VEGFR2通路在毛囊角质形成中起直接调节作用。  相似文献   
8.
对原核表达的重组建鲤组织蛋白酶L(Cathepsin L,CAT L)蛋白进行尿素洗涤和Ni-NTA亲和层析纯化,该目的蛋白经300 mmol/L咪唑洗脱为单一峰,SDS-PAGE结合TSK-GEL G2000SWxl凝胶过滤高效液相色谱分析表明重组CAT L获得了高度纯化,分子量约28 k D,纯度超过95%。Z-Phe-Arg-MCA底物测活法显示该重组CAT L表现为半胱氨酸蛋白酶活性,能与其内源抑制因子Cystatin以1︰1的摩尔比结合,具有生物学活性。以纯化的重组CAT L蛋白免疫Balb/C小鼠获得抗血清,经ELISA法检测获得的CAT L抗血清效价高于1︰512000;Western blotting鉴定结果表明该抗体具有良好的特异性,能够识别原核表达的重组CAT L蛋白。免疫组织化学分析结果表明,该抗体还能识别建鲤小肠、肝胰脏、脾、背肌和心肌组织表达的内源性CAT L蛋白。因此可利用该抗体从蛋白水平检测CAT L在鱼类不同组织中的表达和分布情况。  相似文献   
9.
以父母代固始鸡为试验材料,用添加不同剂量的白细胞介素2(IL-2)佐剂的鸡志贺氏菌苗对试验鸡进行分组免疫,应用免疫组织化学技术,通过Owin图像处理系统对鸡十二指肠内分泌型免疫球蛋白A(SIgA)阳性细胞反其分泌物的分布和阳性面积进行系统分析.结果表明,SIgA阳性细胞主要分布于十二指肠肠黏膜的固有膜及肠腺腔中,在志贺菌组中添加IL-2能够提高SIgA细胞的分泌,从而提高动物体的免疫能力,且以IL-2的添加剂量在50μg时对增加志贺菌苗的免疫性效果最佳.  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