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   476篇
  免费   22篇
  国内免费   38篇
林业   6篇
农学   8篇
基础科学   2篇
  13篇
综合类   124篇
农作物   9篇
水产渔业   12篇
畜牧兽医   271篇
园艺   91篇
  2023年   9篇
  2022年   7篇
  2021年   15篇
  2020年   17篇
  2019年   26篇
  2018年   15篇
  2017年   21篇
  2016年   28篇
  2015年   19篇
  2014年   25篇
  2013年   25篇
  2012年   34篇
  2011年   34篇
  2010年   30篇
  2009年   37篇
  2008年   18篇
  2007年   51篇
  2006年   18篇
  2005年   9篇
  2004年   25篇
  2003年   14篇
  2002年   16篇
  2001年   7篇
  2000年   7篇
  1999年   5篇
  1998年   14篇
  1997年   3篇
  1994年   1篇
  1992年   3篇
  1991年   1篇
  1990年   1篇
  1956年   1篇
排序方式: 共有536条查询结果,搜索用时 15 毫秒
31.
郭琼林 《水产学报》2000,24(4):349-353
草鱼淋巴细胞表面扫描电镜结构特征为有孔穴且较为光滑、具短小细锥状突起;中华鳖淋巴细胞、胸腺细胞表面扫描电镜结构特征为凹凸不平、较为光滑;它们均以表面凹凸不平特征的占大多数。E花环试验的光镜和扫描电镜观察显示:草鱼淋巴细胞E花环形成不明显,而中华鳖淋巴细胞、胸腺细胞的成花率分别为25%-34%和36%-47%,能形成花环的淋巴细胞、胸腺细胞以表面结构特征凹凸不平(类似哺乳动物T淋巴细胞)的为主。草鱼、中华鳖血液淋巴细胞和中华鳖胸腺细胞与抗人CD2单克隆抗体交叉反应的免疫组化检测显示中华鳖血液淋巴细胞和胸腺细胞的CD2阳性率分别为24%和33%。草鱼血液淋巴细胞CD2阳性反应不明显。  相似文献   
32.
33.
Streptococcus agalactiae is a Gram‐positive facultative intracellular bacterium that leads to severe economic loss of tilapia worldwide. Previous studies demonstrated that CD40 contributes to host protection against intracellular injection. In this study, CD40 was characterized from Nile tilapia (Oreochromis niloticus), named OnCD40. Sequence analysis showed that open reading frame of OnCD40 was 933 bp, containing a single peptide, a transmembrane domain and four cysteine‐rich domains. The qRT‐PCR revealed that OnCD40 was expressed in all examined tissues with the most abundant ones in spleen and thymus. After S. agalactiae stimulation, the expression of OnCD40 was significantly induced in most of the detected organs. Moreover, OnCD40‐overexpressing fish elicited significant protection against subsequent S. agalactiae challenge; approximately 10000‐fold fewer bacteria were detected in spleen of OnCD40‐overexpressing fish in comparison with control fish. Thus, CD40 had protecting function in Nile tilapia against intracellular pathogens.  相似文献   
34.
Abstract— Epidermotropic cutaneous T-cell lymphoma was diagnosed in six Syrian hamsters (Mesocricetus auratus) with a generalised dermatosis characterised by pruritus, alopecia and exfoliative erythroderma. Plaques and nodules were evident in one animal. Clinical and histopathological findings were suggestive of mycosis fungoides and electron microscopical investigations in one case were supportive. Immuno-histochemical stains for CD3 antigen were strongly positive in all cases. Résumé— Un lyphome T cutané a été diagnostiqué chez six hamsters de Sibérie (Mesocricetus auratus) avec une dermatose généralisée, caractérisée par un prurit, une alopécle et une érythrodermie exfoliative. Des plaques et des nodules ont été observées sur un animal. Les données cliniques et histopathologiques étaient évocatrices d'un mycosis fungoïdes et les examens en microscopie électronique étaient compatibles dans un cas. Les marquages immuno-histochimiques de l'antigène CD3 étaient très positifs dans tous les cas. Zusammenfassung— Bei sechs Syrischen Goldhamstern (Mesocricetus auratus) wurde ein epidermotropes kutanes T-Zell-Lymphom mit einer generalisierten Dermatose diagnostiziert, die durch Pruritus, Alopezie und eine exfoliative Erythrodermie gekennzeichnet war. Bei einem Tier traten auch Plagues und Knoten auf. Die klinischen und histopathologischen Befunde deuteten auf Mycosis fungoides hin. Elektronenmikroskopische Untersuchungen unterstützten diesen Verdacht in einem Fall. Immunhistochemische Färbungen auf CD3-Antigen waren bei alien Fallen stark positiv. Resumen En un grupo de seis hamsters de siria, (Mesocricetus auratus), se diagnosticó limfoma epidermotrópico cutáneo de linfocitos T, presentando una dermatosis generalizada de tipo pruriginoso, acompañada de alopecia y eritroderma exfoliativo. Las placas y nódulos fueron evidentes en uno de los animales. Los estudios clinicos e histopatológicos indicaron una micosis fungoide, y las investigaciones de microscopía, en uno de los caseos, pareció indicar lo mismo. La tintura inmuno-histoquimica para el antígeno CD3 resultó claramente positiva en todod los casos.  相似文献   
35.
为研究黑龙江垦区经济增长问题,首先对柯布-道格拉斯(CD)生产函数进行变形,具体将资本与劳动力投入细化到三种产业得到变形的生产函数,同时建立人工神经网络模型对新的生产函数进行模拟。为反映单个产业自身的投资累积效应,进一步引入自反馈环建立递归神经网络(RNN)模型。该模型可确定投资诸要素间关系,同时反映产业本身及产业结构间的内在联系。数值试验证明该变形生产函数及其RNN模型符合实际,且网络结构简单、算法易于实现、模拟及预测精度高,该算法还可广泛用于投资决策、投资产出预测等经济增长问题。  相似文献   
36.
A 9‐month‐old male Great Dane had progressive generalized nodular dermatopathy for several months. There were > 100 raised, alopecic, firm, painful nodules throughout the skin. Aspirates from several lesions yielded moderate numbers of irregularly round or polygonal to spindle‐shaped cells with mild to moderate anisocytosis and few inflammatory cells, and the cytologic interpretation was proliferation of mesenchymal or histiocytic cells. On histopathologic examination, nodules were composed of densely packed sheets of round to spindle‐shaped cells with mild anisokaryosis and low mitotic activity. Multifocal histiocytic sarcoma with a spindle‐cell pattern was diagnosed based on morphologic features and intense expression of CD18. Additional immunophenotypic analysis on frozen sections of tissue confirmed the diagnosis of histiocytic sarcoma; expression of CD18, CD45, CD1a, CD11b, and CD11c, limited expression of Thy‐1 (CD90) and CD80, and lack of expression of CD4, CD11d, and CD86 indicated that the cells were likely interstitial dendritic cells; a review of reactive and neoplastic dendritic cells is provided. Based on staging, internal organs were not affected. Sequential treatment with lomustine and doxorubicin failed to prevent progression of the cutaneous lesions, and the dog died 3 months after initial diagnosis. At necropsy, a focus of neoplastic cells was present in one lymph node, but except for skin other organs were not involved. The clinical presentation of histiocytic sarcoma may be unusual, and neoplastic cells may lack overt features of malignancy on cytologic and histopathologic examination. In some instances, immunophenotyping is required to differentiate histiocytic sarcoma from other histiocytic disorders.  相似文献   
37.
AIM: To investigate the effects of inflammatory cytokines on the expression of fatty acid transporter (FAT/CD36) in renal cells loaded by fatty acids. METHODS: Human mesangial cells (HMCs) and renal tubular epithelial HK-2 cells were treated with palmitate at concentrations of 0 mmol/L, 0.02 mmol/L, 0.04 mmol/L, 0.08 mmol/L, 0.16 mmol/L and 0.32 mmol/L for 24 h. The expression of FAT/CD36 at mRNA and protein levels was detected by real-time PCR and Western blotting,respectively. The renal cells were treated with palmitate at concentration of 0.04 mmol/L combined with TNF-α (25 μg/L) or IL-6 (20 μg/L) for 24 h. The effect of inflammatory cytokines on the mRNA and protein levels of FAT/CD36 in the renal cells was also investigated. Oil red O staining was used to determine the intracellular lipid droplet formation. The intracellular triglyceride (TG) and free fatty acid (FFA) were measured by enzymic assay and ELISA, respectively. RESULTS: Palmitate loading dose-dependently increased the expression of FAT/CD36 at mRNA and protein levels in both HMCs and HK-2 cells. The inflammatory cytokines further increased the expression of FAT/CD36 at mRNA and protein levels in both cells loaded by palmitate. Oil red O staining, TG detection and FFA assay showed that the inflammatory cytokines increased intracellular lipid levels in both HMCs and HK-2 cells. CONCLUSION: Inflammatory cytokines up-regulate the expression of FAT/CD36 in renal cells loaded by fatty acids and exacerbate the intracellular lipid accumulation.  相似文献   
38.
Alveolar macrophages (AMs) constitute the first line of defence in the lung of all species, playing a crucial role in the regulation of immune responses to inhaled pathogens. A detailed understanding of the function and phenotype of AMs is a necessary pre-requisite to both elucidating their role in preventing opportunistic bacterial colonisation of the lower respiratory tract and developing appropriate preventative strategies. The purpose of the study was to characterise this important innate immune cell at the tissue level by making functional and phenotypic comparisons with peritoneal macrophages (PMs). We hypothesised that the tissue of origin determines a unique phenotype of AMs, which may constitute an appropriate therapeutic target for certain equine respiratory diseases. Macrophages isolated from the lung and the peritoneal cavity of 9 horses were stimulated with various toll like receptor (TLR) ligands and the production of nitrite, tumour necrosis factor alpha (TNFα), interleukin (IL) 10 and indoleamine 2,3-dioxygenase (IDO) were measured by the Griess reaction and enzyme linked immunosorbent assay (ELISA) and/or quantitative polymerase chain reaction, respectively. Cells were also compared on the basis of phagocytic-capacity and the expression of several cell surface markers. AMs, but not PMs, demonstrated increased TNFα release following stimulation with LPS, polyinosinic polycytidylic acid (Poly IC) and heat-killed Salmonella typhinurium and increased TNFα and IDO mRNA expression when stimulated with LPS. AMs showed high expression of the specific macrophage markers cluster of differentiation (CD) 14, CD163 and TLR4, whereas PMs showed high expression of TLR4 only. AMs, but not PMs, demonstrated efficient phagocytic activity. Our results demonstrate that AMs are more active than PMs when stimulated with various pro-inflammatory ligands, thus supporting the importance of the local microenvironment in the activation status of the macrophage. This information provides a valuable knowledge base on which to improve our understanding of the role of macrophages and their microenvironment in equine innate immunity.  相似文献   
39.
CD36 is a scavenger receptor involved in lipid uptake and inflammation. Recently, non-cell-bound CD36 (sCD36) was identified in plasma and suggested to be a marker of lipid accumulation in the vessel wall. Marine n-3 polyunsaturated fatty acids (PUFA) may have cardioprotective effects. This study evaluated the effect of marine n-3 PUFA on sCD36 levels in overweight subjects. Fifty overweight subjects were randomized to 1.1 g of n-3 PUFA or 2 g of olive oil daily for six weeks. Neutrophils were isolated at baseline and after six weeks of treatment while an adipose tissue biopsy was obtained at baseline. The content of n-3 PUFA in adipose tissue and neutrophils was analyzed by gas chromatography, while plasma levels of sCD36 were determined using an enzyme-linked immunosorbent assay (ELISA). After six weeks of supplement plasma sCD36 did not differ between supplements (P = 0.18). There was no significant correlation between plasma sCD36 levels and n-3 PUFA in neutrophils at baseline (r = −0.02, P = 0.88), after six weeks supplement (r = −0.03, P = 0.85) or in adipose tissue (r = 0.14, P = 0.34). This study therefore does not provide evidence for a cardioprotective effect of n-3 PUFA acting through a CD36-dependent mechanism.  相似文献   
40.
Minimally invasive techniques used to evaluate canine peripheral lymphadenopathy (PLN), including fine needle aspiration biopsy with cytological evaluation (FNAB‐C) and flow cytometry (FC), have benefits and limitations. The cell block (CB) method is an alternate processing technique in which fine needle aspirate biopsy samples are concentrated, fixed, and embedded in paraffin for routine histological processing/staining. Utilizing three observers, we determined the diagnostic value of the CB in evaluating canine PLN across six categories (non‐diagnostic, reactive, inflammatory/infectious, probable lymphoma and lymphoma, metastatic neoplasia) and correlated findings to immunophenotypic and clonal antigen receptor rearrangement results in canine nodal lymphoma. Eighty‐five paired FNAB‐C and CB samples were evaluated from canine patients presenting to the University of Minnesota Veterinary Oncology or Internal Medicine services. Diagnostic quality samples were obtained in 55/85 (65%) CB and 81/85 (95%) FNAB‐C samples, respectively, and nodal pathology impacted CB diagnostic yield. Overall percent agreement between diagnostic‐quality FNAB‐C and CB samples was 86%, but increased to 95% if the categories of lymphoma and probable lymphoma were combined. There was 100% agreement for both the diagnoses of metastatic neoplasia and reactive lymph nodes and 92% agreement for the diagnosis of lymphoma/probable lymphoma. Using immunohistochemistry (IHC), CB samples correctly immunophenotyped 22/23 (96%) cases of B‐cell lymphoma, but only 1/6 (17%) cases of T‐cell lymphoma. IHC was not completed on nine cases of lymphoproliferative disease because of insufficient cellularity. When the CB method (CBM) yielded diagnostic quality samples there was good to excellent agreement with FNAB‐C samples and CB samples were suitable for some IHC tests.  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