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   18167篇
  免费   1415篇
  国内免费   1270篇
耳鼻咽喉   76篇
儿科学   365篇
妇产科学   136篇
基础医学   2994篇
口腔科学   69篇
临床医学   1213篇
内科学   5508篇
皮肤病学   189篇
神经病学   489篇
特种医学   235篇
外科学   1353篇
综合类   2389篇
现状与发展   3篇
预防医学   1400篇
眼科学   70篇
药学   1576篇
  9篇
中国医学   1629篇
肿瘤学   1149篇
  2024年   46篇
  2023年   455篇
  2022年   749篇
  2021年   1109篇
  2020年   1058篇
  2019年   764篇
  2018年   641篇
  2017年   796篇
  2016年   810篇
  2015年   846篇
  2014年   1355篇
  2013年   1362篇
  2012年   1038篇
  2011年   1266篇
  2010年   853篇
  2009年   745篇
  2008年   825篇
  2007年   852篇
  2006年   751篇
  2005年   584篇
  2004年   434篇
  2003年   471篇
  2002年   347篇
  2001年   324篇
  2000年   301篇
  1999年   266篇
  1998年   195篇
  1997年   169篇
  1996年   171篇
  1995年   143篇
  1994年   152篇
  1993年   108篇
  1992年   93篇
  1991年   81篇
  1990年   73篇
  1989年   102篇
  1988年   94篇
  1987年   62篇
  1986年   67篇
  1985年   54篇
  1984年   62篇
  1983年   25篇
  1982年   37篇
  1981年   25篇
  1980年   22篇
  1979年   17篇
  1978年   12篇
  1977年   15篇
  1976年   11篇
  1974年   4篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
ABSTRACT. Serum concentrations of sulphasalazine and sulphapyridine were measured during the first week of life in 15 children whose mothers had been on sulphasalazine during pregnancy. The serum concentrations of sulphapyridine and sulphasalazine were similar in the children and their mothers at delivery. The elimination rate of the drugs in the newborn children was slow but the concentrations were not so high that a bilirubin displacing effect could be expected. In eight mothers who were breast-feeding and taking sulphasalazine, analyses were done of mothers'serum, breast-milk and serum from their children. The results showed that the amount of sulphasalazine and sulphapyridine transferred to the child via the breast-milk is negligible with regard to the risk of kernicterus. It is concluded that a woman in need of sulphasalazine treatment can continue the medication throughout pregnancy and lactation without risk of development of kernicterus in her child. Only term infants without haemolytic disease were included in the study. Thus our conclusion is not necessarily valid for the prematurely born child or the child with haemolytic disease.  相似文献   
52.
目的 观察共刺激分子阻断剂CD80单克隆抗体(CD80mAb)在协同未成熟树突细胞(imDC)诱导同种异体大鼠胰十二指肠移植免疫耐受中的作用。方法 建立糖尿病大鼠胰十二指肠移植动物模型;4E5杂交瘤细胞株BABIMC小鼠腹腔注射,抽取腹水,分离纯化后获得CD80mAb;分离供体大鼠骨髓来源DC细胞前体,经GM—CSF、IL-4体外刺激后。再加入IL-10共培养,鉴定为imDC;移植前7d,将2×10^6imDC经静脉途径注射至受体体内,同时分别给予生理盐水1ml、CD80mAb5mg连续14d。结果 四组受体大鼠移植后中位生存时间分别为12.7d、32.4d、50.2d、92.0d,实验组存活时间明显延长;组织学观察发现移植后7dCD80mAb+imDC组移植物形态尚完整,淋巴细胞浸润减少;混合淋巴细胞反应证实移植后7dCD80mAb+imDC组供受体间呈低反应性。结论 共刺激分子阻断剂CD80mAb能够协同imDC诱导受体T细胞对移植物的免疫耐受,降低宿主对移植物的急、慢性排斥反应,延长移植物的存活时间。  相似文献   
53.
54.
Advanced age has been associated with a wide range of defects in both the innate and adaptive immune systems including diminished specific antibody responses that increase the risk of invasive pneumococcal disease (IPD) and limit the effectiveness of vaccines. However, the elderly are a heterogeneous group and measures of overall frailty may be a better indicator of disease susceptibility (or vaccine response) than chronological age alone.  相似文献   
55.
Massive immune hemolysis due to passenger lymphocyte-derived anti-D has not been reported in renal transplantation. A 50-year-old (B-positive) male received a dual deceased-donor kidney transplant (B-negative) for diabetic renal failure. Two weeks post-transplant, the patient developed severe hemolytic anemia. The donor anti-D titer was 1:8. The recipient anti-D titer (zero pre-transplant) increased from 1:4 to 1:16 over 4 days. Rapid hemolysis caused severe anemia, minimum Hb = 4.2 g/dL, while selectively lysing the patient's autologous red cells during this time. The hemolytic anemia did not impair the allografts and subsided without monoclonal B-cell pharmacotherapy or apheresis. The anti-D titer decreased to barely detectable levels at four months and had cleared when checked 2 years post-transplant. Transfusion support subsided after two months. If complications of anemia can be avoided, the deleterious effects of hemolysis may be well tolerated by renal allografts using antigen negative transfusion alone.  相似文献   
56.
自1979年以来,采用全结肠直肠切除、回肠代结肠、分期重建直肠及肛门功能的手术方式,治疗慢性溃疡性结肠炎及结肠息肉症20例。手术方式有四种类型,分两期完成。第一期手术都同时行回肠造瘘,两期手术间隔时间平均9.7个月,已完成两期手术的16例,均未发生严重并发症。这种术式既完全切除了病变肠段,又保留了肛门控制排便的功能,保证了较好的生活质量。但尚存在的问题是夜间污粪。3例作了回肠造袋的患者污粪现象较轻,回肠储存袋的作用尚须进一步研究。  相似文献   
57.
Treatment of rat heart grafts with PUVA, the combination of the photosensitizer 8-methoxypsoralen and longwave ultraviolet light, leads to a prolonged transplant survival in allogeneic recipients. A PUVA treatment of the recipient rats, performed for 7 consecutive days after transplantation, prolonged graft survival even more effectively. This may be due to the systemic immunomodulatory effects of PUVA in the recipient. One of the mediators is urocanic acid, which is transformed by ultraviolet light in the skin from its trans- to the cis-isomer, which, in turn, acts as a mediator on the immune system. An injection of cisurocanic acid into graft recipients for 7 consecutive days after transplantation resulted in prolonged graft survival; in 40% of the rats, permanent graft acceptance was observed. The significance of these results for clinical organ transplantation is discussed.  相似文献   
58.
We have devised assays to detect both circulating alloantibodies to platelets (indirect assay) and platelet-association IgG and IgM (direct assay) using a flow cytometric technique. A variety of patients with immune thrombocytopenia were studied. Employment of a confocal lens in the flow cytometer increased the discrimination power of the instrument. Patients with autoimmune thrombocytopenia (idiopathic thrombocytic purpura [ITP], systemic lupus erythematosus (SLE), lymphoma, leukemia, and drug-induced thrombocytopenia showed a significant increase in platelet-associated antibody. Circulating antibodies to platelets (alloantibodies) were demonstrated in cases of platelet refractoriness and neonatal isoimmune purpura. Day-today precision of the assays ranged from 3% to 6% (coefficient of variation). No interference was shown in the presence of hemoglobin (5 g/L), triglycerides (10 g/L), or polyclonal and monoclonal immunoglobulinemia (50 g/L: IgG, IgA, IgM). The sensitivity of the direct assay was 500 attograms of IgG or IgM platelet.  相似文献   
59.
目的 观察方格星虫提取物对y射线损伤雄性小鼠免疫器官及生殖器官的保护作用.方法 将50只雄性小鼠随机分为正常对照组、模型组及低[0.5g/(kg·d)]、中[1.0g/(kg·d)]、高[2.0g/(kg·d)]3个剂量方格星虫提取物组,每天灌胃给药1次,给药剂量为2.0 mL/kg,灌胃2周后,除正常对照组外,各组均以剂量率为0.83 Gy/h的60Co γ射线进行1次全身照射,照射剂量为5 Gy.于辐照前1 d,辐照后第3天、第14天测定小鼠体重、外周血白细胞数,辐照后第14天测定小鼠胸腺指数、脾指数、骨髓有核细胞计数、睾丸重量指数、精子总数及精子畸形率.结果 方格星虫提取物可使辐照后第3天3个剂量组小鼠外周血白细胞数明显高于模型组(P<0.05),辐照后第14天3个剂量组小鼠的胸腺指数及脾指数明显高于模型组(P<0.05),低、中剂量组小鼠的骨髓有核细胞数显著高于模型组(P<0.05),高剂量组小鼠骨髓有核细胞数显著高于模型组(P<0.01),中、高剂量组睾丸重量指数、精子总数明显高于模型组(P<0.05),中、高剂量组的精子畸形率显著低于模型组(P<0.01).结论 方格星虫提取物对辐射损伤小鼠的免疫器官及生殖器官具有一定的保护作用.  相似文献   
60.
褪黑素对结肠黏膜上皮细胞氧化应激的影响   总被引:3,自引:1,他引:2  
目的 探讨褪黑素对大鼠结肠黏膜上皮细胞氧化应激的影响。方法 在分离培养正常大鼠结肠黏膜上皮细胞基础上,利用FeSO4 H2O2产生*OH攻击制备结肠黏膜细胞氧化损伤模型,同时预先加入褪黑素并观察损伤减轻程度。实验设正常对照组、模型对照组、5-氨基水杨酸给药组(0.1mmol/L),褪黑素给药组(0.01、0.1、l.0mmol/L)。培养一定时间后,取上清测乳酸脱氢酶(LDH)、丙二醛(MDA)、谷胱甘肽过氧化物酶(GSHPx)、过氧化氢酶(CAT)、超氧化物歧化酶(SOD)、一氧化氮(NO)和黏液含量。结果 模型组大鼠结肠黏膜上皮细胞:MDA、LDH和NO水平增高,CAT、GSHPX、SOD和黏液含量减少。不同剂量褪黑素呈剂量依赖性的减少LDH释放,抑制MDA和NO的形成,恢复黏液、CAT、GSHPX及SOD水平。结论 褪黑素对大鼠结肠黏膜氧化损伤具有保护作用。  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