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   1705篇
  免费   234篇
  国内免费   38篇
林业   19篇
农学   5篇
基础科学   1篇
  14篇
综合类   150篇
农作物   9篇
水产渔业   137篇
畜牧兽医   1605篇
园艺   3篇
植物保护   34篇
  2024年   6篇
  2023年   42篇
  2022年   43篇
  2021年   86篇
  2020年   111篇
  2019年   123篇
  2018年   67篇
  2017年   75篇
  2016年   87篇
  2015年   83篇
  2014年   95篇
  2013年   122篇
  2012年   82篇
  2011年   95篇
  2010年   79篇
  2009年   86篇
  2008年   54篇
  2007年   74篇
  2006年   60篇
  2005年   60篇
  2004年   53篇
  2003年   38篇
  2002年   31篇
  2001年   44篇
  2000年   32篇
  1999年   41篇
  1998年   34篇
  1997年   17篇
  1996年   20篇
  1995年   19篇
  1994年   16篇
  1993年   15篇
  1992年   9篇
  1991年   7篇
  1990年   9篇
  1989年   14篇
  1988年   6篇
  1987年   7篇
  1986年   7篇
  1985年   5篇
  1984年   5篇
  1983年   3篇
  1982年   2篇
  1979年   4篇
  1978年   2篇
  1976年   1篇
  1975年   1篇
  1974年   1篇
  1973年   1篇
  1956年   1篇
排序方式: 共有1977条查询结果,搜索用时 718 毫秒
171.
针对牙齿组织形态学研究的难点,选择适宜固定液,用EDTA-2Na进行脱钙,完成了牙齿组织石蜡切片的制作。通过确定染色程序及各种染料的最佳作用时间,分别利用Masson三色染色法、传统的苏木精和伊红(HE)染色法对牙齿组织切片进行了染色观察。染色结果表明,与HE染色法相比,Masson三色染色更能使牙齿的各主要成分以不同颜色显现出来,色彩对比鲜明,亮丽润眼,为牙齿组织生理及病理组织形态学研究奠定了基础。针对机体中硬组织的相似特性,该试验方法可以在骨骼、软骨等硬组织的形态学研究中参考、改进并推广使用。  相似文献   
172.
173.
基因芯片技术检测5种马病毒   总被引:8,自引:0,他引:8  
通过分子克隆技术获得马疱疹病毒1型(Equineherpesvirus1,EHV1)、马动脉炎病毒(Equinearteritisvirus,EAV)、马流感病毒(Equineinfluenzavirus,EIV)、马传染性贫血病毒(Equineinfectiousanaemiavirus,EIAV)和东部马脑脊髓炎病毒(East-ernequineencephalomyelitisvirus,EEEV)等5种病毒各一段高度保守的特异性基因片段,用芯片点样仪逐点分配到处理过的玻片上,制备成检测芯片。提取样品中的RNA,进行反转录和荧光标记后滴加到芯片上进行特异性杂交,对杂交结果进行扫描检测和计算机软件分析。结果显示,制备的基因芯片可同时检测和鉴别上述5种病毒,可检测到阳性杂交信号的最高稀释度为10-6的病毒液,约25个病毒DNA拷贝,但其它病毒材料未见红色荧光信号,证明了本方法的特异性。在进口马的隔离检疫期间,采集马鼻肺炎、马动脉炎中和抗体阳性但病毒分离阴性马匹的白细胞悬液,分别在EHV1和EAV位点处可检测到阳性杂交信号。证明基因芯片技术不但快速、准确和敏感,而且可同时进行多种病毒的检测。  相似文献   
174.
采用Danscher氏组织学技术测定了口服不同剂量亚硒酸钠中毒奶山羊的心脏、肝脏、脾脏、肺脏、肾脏和大脑硒含量与分布状态;探讨了各组织器官局部病变程度与硒分布密度之间的内在联系。结果表明,中毒羊各组织器官,尤其是发生病理变化的局部组织均蓄积不同密度的反应产物;各组织局部病变程度与硒的分布密度有关,Danscher组织化学技术将组织硒含量与病理变化程度联系起来,为研究动物中毒病的一个实用手段。  相似文献   
175.
Olivier M.  Lepage  DMV  MSc  Renée  Léveillé  DMV  Luc  Breton  DMV  MSc  Marcel  Marcoux  DMV  MSc 《Veterinary radiology & ultrasound》1995,36(5):384-386
An 11-month-old Thoroughbred colt was presented with a hard swelling at the proximal third of the right 4th metatarsal bone. A medial dislocation of the deep digital flexor tendon ( flexor digitorum profundus ) was also observed on the same leg. On the plantaroproximal-plantarodistal projection of the calcaneus, there was flattening and shortening of the sustentaculum tali. The smooth bony proliferation at the proximal third of the right 4th metatarus was compatible with a chronic splint bone fracture. This report describes a medial deep digital flexor dislocation associated with hypoplasia of the sustentaculum tali .  相似文献   
176.
Magnetic resonance imaging (MRI) was performed on gthe brain of 5 normal, anesthetized, neonatal (age 3-to-6 days) Quarter Horse foals. The objectives of the study were to develop a technique for imaging the brain of neonatal foals, and to ascertain their normal brain anatomy. Interavenous propofol was administered for induction and maintenance of general anesthesia. Using spin echo MR techniques, T1 weighted sagittal and transverse views, and spin density and T2 weighted transverse views were successfully made of each foal. MR images provided excellent visualization of many anatomic struictures of the brain and head. MRI of the bgrain is feasible for selected neonantal equine patients.  相似文献   
177.
African swine fever is a viral haemorrhagic disease of pigs which has been used as a model for the study of viral haemorrhagic diseases in man. The acute course of the disease is characterized by acute proliferative glomerulonephritis, with viral replication in mesangial cells and occasional focal necrosis of the renal tubular system; hyperplasia of the collecting ducts is associated with evident virus replication. Haemorrhages have been attributed to endothelial dysfunction, aggravated by virus replication in endothelial cells in the final stages of the disease. The renal interstitium displays intense oedema and an infiltrate largely composed of macrophages. Virus replication has also been observed in fibroblasts and in the smooth0muscle cells of arterioles and venules.In subacute-chronic forms of the disease, various types of glomerulonephritis are observed, ranging from mesangial proliferative glomerulonephritis to focal and segmental hyalinosis associated with immune-mediated phenomena. No striking changes are reported in the renal tubular system. Interstitial haemorrhages are associated with diapedesis due to immunologically mediated events. The interstitium has also been found to contain a lymphohistiocytic infiltrate with abundant plasma cells. No evidence has been reported of viral replication in any cell population.Abbreviations ASF African swine fever - ASFV African swine fever virus - C complement component - DNA deoxyribonucleic acid - HAD50 50% haemoadsorbing doses - Ig immunoglobulin - MPS mononuclear phagocytic system - PAS periodic acid-Schiff reagent  相似文献   
178.
A submental approach using a 5, 7.5 and 10 MHz mechanical sectorial transducers was used to evaluate the ultrasonographic appearance of the normal and abnormal canine, feline and equine tongue. Seven normal animals were used to characterize the in vivo normal ultrasonographic appearance of the oropharynx. Consistently seen anatomical landmarks included the lingual parenchyma, lingual artery, soft and hard palate interfaces, mandible, basihyoid bone and sublingual musculature. Seven fresh canine, feline and equine cadavers were dissected to confirm the ultrasonographic findings. Seven animals with signs of ptyalism, dysphagia, halitosis and visible lingual lesions were also studied. A foreign body and abscesses secondary to a penetrating wound were detected in a horse. Ultrasound guidance aided surgical dissection, removal of the foreign body and intraoperative drainage of the abscesses. Ultrasound provided valuable non-invasive documentation of the architecture, size and margins of six lingual neoplasms. Ultrasonographic monitoring of the response to the treatment of lingual lesions may be beneficial in the management of patients.  相似文献   
179.
Collagenase-induced lesions of the superficial digital flexor tendon were monitored using diagnostic ultrasound and subsequently compared with gross and microscopic findings. The postinjury sonograms demonstrated hypoechoic or anechoic areas corresponding to areas of hemorrhage and necrosis. The size of the lesion increased and the echogenicity decreased with increasing units of collagenase injected into the tendon. As postinjury time increased, echogenicity increased, which corresponded to fibrous-tissue invasion and collagen deposition. The extent of tendon injury produced correlated with the amount of collagenase injected into the tendon. Diagnostic ultrasound is useful in evaluating injury and healing in collagenase— induced tendinitis.  相似文献   
180.
C57B16 mice were immunized with either live, attenuated TC-83 strain VEE virus vaccine or formalin-inactivated VEE vaccine combined with Bordetella pertussis. The kinetics of specific donor and adoptively-immunized recipient anti-VEE neutralizing antibody responses were studied. Donor mice immunized with either live or inactivated VEE virus vaccine combined with potent adjuvants develop specific anti-VEE IgM and IgG responses as early as 7 days post-immunization. Anti-VEE IgM antibody responses comprise the majority of anti-VEE neutralizing antibody at this early time period. By 14 to 21 days post-immunization, anti-VEE IgG responses predominated. When adoptively-immunized recipients were studied, the anti-VEE IgM to IgG predominance seen in donors early after administration was reversed, and for each time-period studied, recipients' serum anti-VEE antibody class responses consisted principally of IgG rather than IgM antibody. Since T-cells cooperation with B-cells is critical in the IgM-IgG antibody shift, these studies support the critical role T-cells exert in adoptive transfer in a murine model of experimental VEE infection. Furthermore, immunization with either live or inactivated VEE vaccine coupled to a potent adjuvant induce comparable donor and adoptively-immunized recipient anti-VEE antibody class responses.  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