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   506篇
  免费   56篇
  国内免费   20篇
林业   11篇
农学   25篇
基础科学   14篇
  3篇
综合类   118篇
农作物   18篇
水产渔业   5篇
畜牧兽医   293篇
园艺   89篇
植物保护   6篇
  2024年   4篇
  2023年   4篇
  2022年   18篇
  2021年   36篇
  2020年   30篇
  2019年   32篇
  2018年   20篇
  2017年   36篇
  2016年   23篇
  2015年   31篇
  2014年   40篇
  2013年   27篇
  2012年   23篇
  2011年   30篇
  2010年   16篇
  2009年   23篇
  2008年   19篇
  2007年   32篇
  2006年   14篇
  2005年   19篇
  2004年   10篇
  2003年   7篇
  2002年   10篇
  2001年   13篇
  2000年   7篇
  1999年   2篇
  1998年   3篇
  1997年   6篇
  1996年   4篇
  1995年   8篇
  1994年   5篇
  1993年   3篇
  1992年   5篇
  1991年   3篇
  1989年   2篇
  1988年   2篇
  1987年   2篇
  1986年   3篇
  1985年   1篇
  1983年   3篇
  1981年   2篇
  1980年   3篇
  1979年   1篇
排序方式: 共有582条查询结果,搜索用时 62 毫秒
61.
Abnormal pulmonary radiopacities were identified in 13 racing horses in which a diagnosis of exercise-induced pulmonary hemorrhage (EIPH) had been confirmed. The lesions were in the caudal lung lobe in all horses; seven were on the right and three on the left, and the laterality for three could not be determined. In ten horses the opacities, which were large and peripherally located, obliterated the thoracophrenic angle. They merged with the silhouette of the diaphragm and had a circular or ovoid surface directed toward the hilum. The intensity of opacification of the consolidated areas varied, and they often were not sharply marginated. Dorsal displacement of the pulmonary arteries was noted in the region of the radiopacity in seven horses. Varying volumes of pleural effusion were observed in nine horses. Serial radiographic examinations were performed in seven horses. The pulmonary radiopacities cleared within ten days in two horses. In the remaining five horses, gradual resolution, characterized by a reduction in lesion size with improved margination, occurred during several months. The central region of the radiopaque lesion commonly had a patchy appearance, suggesting cavitation. Normal pulmonary vascular and interstitial markings were evident following complete resolution of these lesions. The cause of these abnormal pulmonary opacities has not been determined. Pathologic-radiologic correlations will be required to improve understanding of the pathophysiology of EIPH in the racing horse.  相似文献   
62.
Paraffin blocks and mineral oil were used as a model to determine the effect of dependency versus nondependency on radiographic visualization of lung lesions in lateral thoracic radiographs. It was concluded that the increased opacity of the material surrounding the lesion, not contact between the heart and the lesion, was responsible for the inability to detect lung disease in the dependent lung. The results were tested in dogs with pneumonia in the right middle lung lobe. When the dog was in right lateral recumbency, the dependent right lung was increased in opacity and decreased in volume and the pulmonary lesion was difficult to detect. When the dog was in left lateral recumbency, the nondependent right lung was increased in volume and decreased in opacity and the pulmonary disease was clearly visible. A single recumbent lateral radiograph must not be used to assess a dog with suspected lung disease because lesions in the dependent lung lobes may not be detected.  相似文献   
63.
The inhalation of grain dust by grain workers is responsible for a large number of pulmonary pathophysiologies. These problems may be acute or chronic and may be mediated by the chronic activation of the immune system. Constant inflammatory states in the lung may eventually lead to tissue damage and respiratory deficit. This study was designed to measure the changes in the relative number of inflammatory cells in peripheral blood, bronchoalveolar spaces, and lung interstitium that occur in response to intratracheally instilled airborne spring wheat dust in rats. It was found that 6h after instillation with dust, neutrophils were present in greater numbers in the blood and bronchoalveolar spaces than in lung interstitium. After 24h, there appeared to be a larger number of neutrophils in the lung interstitium in dust-instilled animals than in saline-instilled controls. These results indicate that intratracheal instillation of grain dust initiates an acute inflammatory reaction, and that there is an initial influx of neutrophils into the air spaces of the lung followed by transit of these cells into the lung interstitium.  相似文献   
64.
姜杰  劳逸 《湛江医学院学报》1996,14(4):311-311,314
对70例肺癌患者随机分为两组,用改进麻醉及插管方法与常规方法作了对经研究,结果表明:在改进法组中,患者剧烈咳嗽,支气管痉挛和咯血等并发症明显减少,并对两组并发症的治疗作了讨论。  相似文献   
65.
An outbreak of pulmonary adenomatosis (OPA) occurred in sheep in Patagonia, Argentina's southernmost region. On the affected farm, nine animals died over a 6-month period with pulmonary lesions of OPA. In all cases, the histology of the lungs was characterized by proliferation of cuboideal and prismatic cells lining the alveoli. Inflammatory exudates and accumulation of alveolar macrophages were marked in most cases, but in six of the cases there was no excess fluid in the airways. The presence of the Jaagsiekte retrovirus was demonstrated in the lungs by immunocytochemistry and PCR. To the best of our knowledge, this is the first report of OPA in Patagonia.  相似文献   
66.
藏猪肺组织与高原低氧适应性的初步研究   总被引:1,自引:0,他引:1  
利用光镜和计算机图像分析系统观察了6月龄藏猪和三元杂交(长白×约克×杜洛克)生长肥育猪(简称白猪)的肺组织结构和肺动脉血管结构特性,并就藏猪的肺组织结构特点与高原低氧适应性进行了探讨。结果表明:(1)藏猪与白猪单位面积肺泡数(MAN)差异不显著(P>0.05),但藏猪肺泡膈厚度(MAST)明显大于白猪,差异显著(P<0.05),肺泡膈内毛细血管丰富;(2)藏猪的肺动脉大多为肌性动脉和弹性动脉,白猪的大多为部分肌性动脉,弹性动脉仅占23.1%;(3)藏猪肺动脉管径小、管壁厚,肺动脉中膜基层占血管外径的百分率(MT)高。由此可见,藏猪的肺动脉平滑肌含量丰富,该结果可为藏猪和引进外来猪种对高原低氧适应性结构机理和解决平原地区的动物引进高原并适应高海拔的低氧环境及保持正常的生产能力提供理论依据。  相似文献   
67.
Relmβ亦称发现于炎症带2(found in inflammatory zone2,FIZZ2),是一种富含半胱氨酸的分泌蛋白。目前的研究表明,Relmβ在许多方面发挥着非常重要的作用,包括胰岛素抵抗,抵制肠腔寄生线虫的感染,预测胃肠道肿瘤的发生,促进小鼠结肠炎和回肠炎模型中的炎症反应,诱导肺部纤维化、缺氧肺血管的重建,促进气道重塑等。通过对Relmβ分子的结构、表达分布、生物学功能的研究进展进行归纳,为Relmβ分子在生物学和医学方面更深入的研究提供参考。  相似文献   
68.
研究药用植物蒲公英内生真菌PG23多糖对肺癌A549细胞的抑制作用。蒲公英内生真菌PG23通过培养,乙醇沉淀获得粗多糖、苯酚-硫酸法测定多糖含量,采用MTT法测定PG23多糖对肺癌A549细胞的抑制率,并计算半抑制浓度(IC50)。结果表明,PG23发酵液中多糖得率为2.754%,多糖含量为26.82%;对A549肺癌细胞的抑制率以第1天为最高;抑制率不与多糖浓度成比例,最佳作用浓度为14.42μg/mL,抑制率为87.63%(P<0.01),IC50为1.073mg/mL(24h)。PG23发酵液多糖对肺癌A549细胞具有较强的抑制能力。  相似文献   
69.
70.
The association of cryptorchidism, functional Sertoli cell tumors, and spermatic cord torsion has been rarely reported in the literature. Two dogs were admitted for bilateral skin alopecia and weight loss. Both animals were cryptorchid and displayed a pendulous preputial sheath, prostate hypertrophy, and increased levels of circulating oestrogen. Transabdominal palpation and ultrasonography revealed the presence of neoplastic retained gonads. During surgery, spermatic cord torsion was also detected in the enlarged neoplastic testes of both dogs. Histologic examination confirmed the presence of Sertoli cell tumors that were primarily responsible for the feminizing syndrome. Complete remission of all symptoms occurred within 3 months after orchiectomy.  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