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   4643篇
  免费   247篇
  国内免费   182篇
耳鼻咽喉   358篇
儿科学   29篇
妇产科学   26篇
基础医学   770篇
口腔科学   78篇
临床医学   122篇
内科学   388篇
皮肤病学   248篇
神经病学   371篇
特种医学   66篇
外科学   615篇
综合类   852篇
预防医学   144篇
眼科学   159篇
药学   671篇
中国医学   143篇
肿瘤学   32篇
  2023年   15篇
  2022年   18篇
  2021年   46篇
  2020年   54篇
  2019年   54篇
  2018年   56篇
  2017年   74篇
  2016年   87篇
  2015年   97篇
  2014年   142篇
  2013年   188篇
  2012年   174篇
  2011年   172篇
  2010年   149篇
  2009年   153篇
  2008年   184篇
  2007年   195篇
  2006年   234篇
  2005年   189篇
  2004年   201篇
  2003年   195篇
  2002年   183篇
  2001年   164篇
  2000年   147篇
  1999年   125篇
  1998年   111篇
  1997年   127篇
  1996年   118篇
  1995年   99篇
  1994年   99篇
  1993年   83篇
  1992年   101篇
  1991年   94篇
  1990年   92篇
  1989年   81篇
  1988年   74篇
  1987年   73篇
  1986年   58篇
  1985年   89篇
  1984年   85篇
  1983年   73篇
  1982年   53篇
  1981年   53篇
  1980年   37篇
  1979年   35篇
  1978年   38篇
  1977年   26篇
  1976年   22篇
  1974年   12篇
  1973年   15篇
排序方式: 共有5072条查询结果,搜索用时 15 毫秒
81.
IHA和Slide诊断旋毛虫病的研究   总被引:1,自引:0,他引:1  
目的 :检测感染旋毛虫病豚鼠血清 ,寻求新的诊断旋毛虫病的方法。方法 :采用间接红细胞凝集试验(IHA)和玻片法环蚴沉淀试验 (Slide)。结果 :阳性率分别为 10 0 %和 97.1%。用此两种血清学方法检测正常豚鼠、血吸虫病兔、肺吸虫病大白鼠、蛔虫病人和鞭虫病人血清 ,除 1例肺吸虫病大白鼠血清IHA出现阳性反应外 ,其它血清两种方法均为阴性反应。结论 :提示两种免疫血清学方法对旋毛虫病特异性抗体的检测均具有较好的敏感性和特异性  相似文献   
82.
目的:建立一种炎性胸膜腔积液(简称胸液)的动物模型。方法:选择40只豚鼠分为8组,第1-7组为试验组,第8组为对照组,试验组每只左胸膜腔内注入1%角叉菜胶(carrageenan)0.8-1.0ml,分批处死观察。结果:胸液于1天内已经出现,2-3天积液量最多,胸液中中性粒细胞计数及病理切片中胸膜、肺的炎性改变亦达高峰,以后胸液逐渐吸收,第7天开始出现胸膜纤维化与粘连,第10天时明显,14天呈现胸膜包裹。结论:角叉菜胶是一比较理想的胸膜腔致炎剂;该动物模型的建立,为胸液的进一步研究提供了有用的工具。  相似文献   
83.
Pig organ xenotransplantation offers a solution to the shortage of deceased human organs for transplantation. The pathobiological response to a pig xenograft is complex, involving antibody, complement, coagulation, inflammatory, and cellular responses. To overcome these barriers, genetic manipulation of the organ‐source pigs has largely been directed to two major aims—(a) deletion of expression of the known carbohydrate xenoantigens against which humans have natural (preformed) antibodies, and (b) transgenic expression of human protective proteins, for example, complement‐ and coagulation‐regulatory proteins. Conventional (FDA‐approved) immunosuppressive therapy is unsuccessful in preventing an adaptive immune response to pig cells, but blockade of the CD40:CD154 costimulation pathway is successful. Survival of genetically engineered pig kidneys in immunosuppressed nonhuman primates can now be measured in months. Non‐immunological aspects, for example, pig renal function, a hypovolemia syndrome, and rapid growth of the pig kidney after transplantation, are briefly discussed. We suggest that patients on the wait‐list for a deceased human kidney graft who are unlikely to receive one due to long waiting times are those for whom kidney xenotransplantation might first be considered. The potential risk of infection, public attitudes to xenotransplantation, and ethical, regulatory, and financial aspects are briefly addressed.  相似文献   
84.
袁胜男  张新庄  刘婧  范小雪  曹亮  王振中  肖伟 《中草药》2023,54(10):3197-3204
目的 探讨杏贝止咳颗粒对豚鼠感染后咳嗽(post-infectious cough,PIC)的治疗作用。方法 除对照组外,将3~4周龄SPF级雄性Hartley豚鼠采用鼻滴脂多糖、烟熏、辣椒素雾化激发来构建PIC豚鼠模型。造模成功后分为模型组及杏贝止咳颗粒低、中、高剂量(0.93、1.86、3.72 g/kg)组、阿斯美(21.62 mg/kg)组和苏黄止咳胶囊(313.88 mg/kg)组,末次给药后24 h,通过辣椒素雾化诱咳测定咳嗽次数及潜伏期,采用ELISA法检测血清、肺泡灌洗液和肺组织中P物质(substance P,SP)、降钙素相关基因肽(calcitonin gene related peptide,CGRP)、神经肽A(neurokinin A,NKA)、神经肽B(neurokinin B,NKB)、神经生长因子(nerve growth factor,NGF)、前列腺素E2(prostaglandin E2,PGE2)和缓激肽(bradykinin,BK)含量,血液分析仪测定肺泡灌洗液中白细胞分类,并用苏木素-伊红(HE)染色法观察肺组织病理变化。结果 与对照组比较...  相似文献   
85.
哮喘豚鼠初级传入神经元ERK的表达及NGF的调节作用   总被引:7,自引:2,他引:7  
目的 探讨细胞外信号调节蛋白激酶 (ERK)在哮喘豚鼠初级传入神经元 (C7 T5脊神经节 )的表达及神经生长因子 (NGF)对ERK的调节作用。方法 利用免疫组织化学结合显微图像分析 ,研究哮喘豚鼠C7 T5脊神经节活化的ERK免疫反应变化。结果 与对照组相比 ,哮喘组豚鼠活化ERK免疫反应在C7 T5脊神经节神经元核内明显上调 (P <0 .0 1) ,其阳性细胞比率明显高于对照组。Anti NGF组豚鼠活化ERK免疫反应在C7 T5脊神经节神经元的核中明显低于哮喘组 (P <0 .0 1)。结论 C7 T5脊神经节神经元活化的ERK可能参与哮喘的发病过程 ,NGF可上调哮喘豚鼠C7 T5脊神经节神经元活化的ERK表达  相似文献   
86.
During preparation of cells for experimentation a considerable amount of bound substance is lost. Our aim was to develop a protocol which retained lectin binding to an extent similar to living cells. This procedure would use fixation procedures suited for fluorescent lectin conjugates and gold-conjugates to be visualized by light- and electron microscopy, respectively. We tested glutaraldehyde and paraformaldehyde in different concentrations before and after lectin binding, different buffers and divalent cations, as additives, to determine the effects on preservation of lectin binding. Lectin binding was visualized and semiquantitatively evaluated by image analysis in the light microscope after silver enhancement of lectin-gold conjugates and by using tetramethyl rhodaminyl isothiocyanate (TRITC)-conjugated lectins. Preservation of lectin binding was best visualized with fluorescent lectin conjugates, whereas during silver enhancement procedures of gold-conjugated lectins, a considerable amount of bound lectins was lost. In general, lectin binding to living cells followed by fixation is superior to fixation before lectin binding. Unfavourable combinations of fixatives and buffers can cause a loss of more than 90% bound lectin. In our experiments with freshly isolated guinea pig cardiomyocytes, lectin binding was best when we used Na-cacodylate buffer with glutaraldehyde fixation (0.1%) after binding of lectins to the living cells.  相似文献   
87.
88.
89.
The ontogeny of lymphocytes expressing J chain in the cytoplasm (J+) was studied in pig foetuses by the immunofluorescent technique. Peripheral blood lymphocytes were the first J+ cells in prenatal life. The spleen and lymph nodes contained J+ cells in the last days of gestation. J+ cells were found in the lamina propria of the gut and some glands of conventional but not of germ-free piglets. J chain was not detected on or in cell membranes at any developmental stage.  相似文献   
90.
Rapid and reliable assessment of hepatic graft viability is important for successful orthotopic liver transplantation (OLTx). OLTx was performed in 11 pairs of pigs via a venovenous bypass. Six of these grafts were transplanted immediately (group A), while the other five were preserved in University of Wisconsin (UW) solution for 24 h and then transplanted (group B). All grafts were flushed with 300 ml of chilled (4°C) Ringer's lactate solution before reperfusion of the graft, when 20 ml of effluent from the graft was collected and the concentrations of ammonia, lactic acid, GOT, and LDH were measured. Four of the six pigs in group A survived longer than 3 days, while the other two pigs died of causes other than graft dysfunction. All five pigs in group B died either of hemoperitoneum or hemodynamic instability due to liver failure. The histology of postperfusion biopsies in group A showed minimal pathological changes, while the grafts in group B revealed moderate to severe ischemic injuries. Ammonia and lactic acid in the effluent of group B were significantly higher than those of group A (1511±216 vs 417±333 g/dl and 114.1±12.2 vs 91.4±12.2 mg/dl, respectively; P<0.05 in both cases). Before reperfusion, the rate of total adenine nucleotides in all of the substances in the graft, which were measured using high performance liquid chromatography (HPLC), inversely correlated with the ammonia levels in the effluent. We conclude that an analysis of the effluent, (i.e. the levels of ammonia and lactic acid), flushed from a hepatic graft before reperfusion could serve as a predictor of hepatic graft viability.  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