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   2034篇
  免费   135篇
  国内免费   45篇
耳鼻咽喉   16篇
儿科学   95篇
妇产科学   26篇
基础医学   141篇
口腔科学   42篇
临床医学   284篇
内科学   325篇
皮肤病学   44篇
神经病学   63篇
特种医学   288篇
外科学   292篇
综合类   205篇
预防医学   139篇
眼科学   16篇
药学   117篇
  2篇
中国医学   32篇
肿瘤学   87篇
  2022年   30篇
  2021年   32篇
  2020年   30篇
  2018年   21篇
  2017年   22篇
  2016年   18篇
  2015年   33篇
  2014年   48篇
  2013年   74篇
  2012年   77篇
  2011年   84篇
  2010年   90篇
  2009年   104篇
  2008年   68篇
  2007年   78篇
  2006年   80篇
  2005年   53篇
  2004年   48篇
  2003年   50篇
  2002年   46篇
  2001年   37篇
  2000年   27篇
  1999年   29篇
  1998年   83篇
  1997年   74篇
  1996年   72篇
  1995年   68篇
  1994年   41篇
  1993年   50篇
  1991年   19篇
  1990年   14篇
  1989年   30篇
  1988年   42篇
  1987年   39篇
  1986年   29篇
  1985年   33篇
  1984年   19篇
  1983年   24篇
  1982年   16篇
  1980年   16篇
  1977年   15篇
  1976年   14篇
  1963年   17篇
  1960年   14篇
  1959年   22篇
  1958年   29篇
  1957年   19篇
  1956年   30篇
  1955年   42篇
  1954年   35篇
排序方式: 共有2214条查询结果,搜索用时 0 毫秒
61.
郑武  笪琴  张薇  汤恒  彭国平 《实用预防医学》2018,25(11):1325-1328
目的 分析湖北省接受艾滋病HAART患者CD4+T淋巴细胞变化趋势及影响因素。 方法 筛选2012年1月1日以后接受HAART的成年患者,利用一般线性模型、重复测量方差分析来分析患者的基线、治疗后6、12个月的CD4+T淋巴细胞计数情况及影响因素。 结果 1 843例研究对象基线CD4+T淋巴细胞计数均值为(218.94±143.96)个/μl,接受HAART后6个月为(334.31±188.62)个/μl,12个月后为(382.79±204.44)个/μl,差异有统计学意义(F=6 856.98,P=0.000)。影响HAART治疗后CD4+T淋巴细胞计数上升的主要因素是:性别、开始治疗年龄、WHO临床分期、初始治疗方案、基线CD4+T淋巴细胞计数。受性别、基线CD4+T淋巴细胞计数、开始治疗年龄、初始治疗方案等影响,治疗后CD4+T淋巴细胞计数随时间推移呈线性上升趋势;其中,女性、开始治疗年龄越小、基线CD4+T淋巴细胞计数越高、初始治疗方案含二线药物的患者上升较快。受WHO临床分期因素影响,治疗后CD4+T淋巴细胞计数随时间推移上升趋势符合二次方曲线方程,WHO临床分期越靠前,上升速度较快。 结论 湖北省艾滋病患者接受HAART后CD4+T淋巴细胞计数上升受多种因素影响,建议针对不同的患者及早开展HAART,提高抗病毒治疗的效果和患者生命质量。  相似文献   
62.
The purpose of this study was to develop a technique to evaluate the implant-abutment gap of an external hexagon implant system as a function of radius. Six implants of 3.75 mm in diameter (Conexao Sistema de Protese Ltda, Sao Paulo, Brazil) and their respective abutments were screw connected and torqued to 20 N cm(-1). The implants were mounted in epoxy assuring an implant long-axis position perpendicular to the vertical axis. Each implant was grounded through its thickness parallel to implant long-axis at six different distance interval. Implant-abutment gap distances were recorded along the implant-abutment region for each section. Individual measurements were related to their radial position through trigonometric inferences. A sixth degree polynomial line fit approach determined radial adaptation patterns for each implant. Micrographs along implant sections showed a approximately 300 mum length implant-abutment engagement region. All implants presented communication between external and internal regions through connection gaps and inaccurate implant-abutment alignment. Average gap distances were not significantly different between implants (P > 0.086). Polynomial lines showed implant-abutment gap values below 10 mum from 0 mum to approximately 250 mum of the implant-abutment engagement region. Gap distances significantly increased from approximately 250 mum to the outer radius of the implant-abutment engagement region. The technique described provided a broader scenario of the implant-abutment gap adaptation compared with previous work concerning implant-abutment gap determination, and should be considered for better understanding mechanical aspects or biological effects of implant-abutment adaptation on peri-implant tissues.  相似文献   
63.
目的 探讨合成一种西地那非类似物的新方法.方法 设计以WG 001-01-08和五硫化二磷为原料,经过硫化得到目标化合物(一种西地那非类似物)的合成路线,并以收率和杂质为指标考察反应试剂、反应温度、加料顺序对反应的影响.结果 成功制备了目标化合物,收率为90%;较佳反应条件为以4-甲基吡啶为溶剂,120℃反应4h,先加WG001-01-08后加五硫化二磷.结论 新方法收率较高,杂质少,反应条件温和,适合工业化生产.  相似文献   
64.
目的:比较自体外周血干细胞移植(APBSCT)与自体骨髓移植治疗CR1期急性髓性白血病(AML)的临床疗效。方法:用APBSCT治疗AML患者27例,用非净化自体骨髓移植(ABMT)治疗AML患者13例,用净化自体骨髓移植(PABMT)治疗AML患者25例。结果:(1)APBSCT组造血重建校其他两组显著加快;(2)APBSCT组的3年无病生存率(DFS)和复发率(RR)分别为51.%和42.2%,与ABMT组的46.2%、46.7%相当,但与净化ABMT组的72.9%、23.7%相比差异有显著性意义。(3)三组的移植相关死亡率(TRM)差异无显著性意义,死亡的主要原因为感染和内脏出血。结论:APBSCT治疗CR1期AML,其造血重建显著快于ABMT,其疗效与ABMT相当,而显著低于PABMT。  相似文献   
65.
The efficacy of immunomagnetic beads to purge human myeloma cells from bone marrow ex vivo was evaluated. The optimal conditions for purging were studied first by using three myeloma cell lines: RPMI-8226, SKO- 007, and SKMM-2. Myeloma cells labeled with the vital fluorescent dye Hoechst 33342 were admixed with normal bone marrow cells, and two monoclonal antibodies reactive with the myeloma cells (PCA-1 and BL-3) were added alone or in combination with the cells. Magnetic beads coated with goat antimouse immunoglobulin G were then added, and the tumor cells to which beads were attached were separated from the mixture with a magnet. The efficacy of tumor cell removal was dependent on the bead-to-tumor ratio; a ratio of more than 500 was optimal in the presence of excess normal marrow cells. The combination of monoclonal antibodies PCA-1 and BL-3 increased the tumor cell removal as compared with either antibody alone. Two cycles of treatment were more effective than one cycle was. Under optimal conditions, 2.3 to 4 logs of tumor cells could be removed from the mixture containing 10% myeloma cells without a significant loss of normal hematopoietic progenitors as measured by CFU-GM, CFU-GEM, and BFU-E. When the efficacy of this procedure was tested on fresh bone marrow from patients with multiple myeloma (MM) by using the combination of PCA-1, BL-3, and J-5, 1.6 to 2.5 logs of tumor cells could be removed by one cycle of treatment, even from marrows containing less than 10% myeloma cells. These observations support the use of monoclonal antibody combinations and immunobeads as a reliable and nontoxic method to eliminate contaminating myeloma cells ex vivo in preparation for autologous bone marrow transplantation in patients with MM.  相似文献   
66.
Oxidative metabolism of the human eosinophil   总被引:14,自引:1,他引:14  
We have compared the oxidative metabolism of human eosinophils (80%-90% purity) to that of neutrophils. Hexose monophosphate (HMP) shunt activity of eosinophils was higher than that of neutrophils under either resting or phagocytizing conditions. Eosinophil HMP shunt activity also was stimulated by phorbol myristate acetate, a membrane- active agent. Eosinophils showed a marked incorporation of 125I into trichloroacetic acid-insoluble material under resting conditions, which increased markedly during phagocytosis. Eosinophils likewise showed a greater reduction of nitroblue tetrazolium dye during phagocytosis than did neutrophils. Measurement of other parameters of oxidative metabolism indicated that eosinophils generated superoxide anion following phagocytosis and also elicited a burst of chemiluminescence similar to that observed during phagocytosis by neutrophils. Measurement of NADPH oxidase activity demonstrated that this enzyme was 3-6 times more active in fractions isolated from eosinophils than in corresponding fractions isolated from neutrophils; this was observed over a range of substrate concentrations. The eosinophil enzyme sedimented differently than the neutrophil enzyme with differential centrifugation; neither showed sedimentation characteristics of peroxidase. These data indicate that eosinophils possess a similar, although in some ways more potent, oxidative burst than neutrophils and are consistent with a role for NADPH oxidase in the initiation of that burst.  相似文献   
67.
Chronic granulocytic leukaemia (CGL) cells which contained a high concentration of unsaturated folate binding protein were incubated in suspension culture for a period of 5 h. Cell samples were periodically assayed for binder and these demonstrated active synthesis which was inhibited by puromycin, cyclo heximide, N-ethylmaleimide, and by incubation at 4 degrees C, but not by actinomycin D. Folate binding activity could also be demonstrated in the culture medium and this increased with the duration of incubation. This release of binder was inhibited by culturing the cells at 4 degrees C and by the addition of N-ethylmaleimide, but not by actinomycin D, puromycin, or cycloheximide. When the pre- and post-culture cell lysates were saturated with tritiated folic acid ([3H]PteGlu) and subjected to chromatography on DEAE-agrarose, approximately half of the bound folate eluted with 0.001 M phosphate buffer at pH 6.0 and the other half eluted with 0.2 M buffer at pH 7.2. The culture medium and plasma from this patient with CGL was well as serum from two normal subjects saturated with [3H]PteGlu and similarly chromatographed contained primarily the acidic binder and much less of the binder eluting with the low molarity buffer. Since a folate binding protein immunochemically similar to the binder in CGL cells has been identified in the serum of non-leukaemic subjects, these experiments suggest that the source of circulating folate binding protein may be the immature granulocyte.  相似文献   
68.
目的:设计一种调节方便,升降安全的截石位手术床腿架。方法:将气弹簧结构应用于截石位腿架中,进行腿架的升降调节,取代原有的通过拧螺丝调节的方法,并将新型腿架应用于泌尿外科80例截石位手术中。结果:此新型腿架单人操作即可,升降调节时无需将患者腿部抬起,操作方便、节省人力,80例手术无1例发生腿部滑落,操作者使用后效果满意。结论:此新型专利解决了截石位腿架调整操作费力及存在安全隐患的问题,值得临床推广使用。  相似文献   
69.
目的研究B超引导下臂丛神经阻滞麻醉的临床效果及安全性。方法将本院行上肢手术的90例患者随机分为对照组(n=48)和B超引导组(n=42)。对照组以盲探的方法行臂丛神经阻滞麻醉,B超引导组在B型超声仪引导下行臂丛神经阻滞麻醉。比较两组的麻醉效果。结果B超引导组感觉阻滞起效时间、麻醉药物使用剂量均优于对照组,但麻醉操作时间长于对照组(P<0.05)。B超引导组不同臂丛神经的感觉阻滞完善率均高于对照组,并发症总发生率低于对照组(P<0.05)。结论与盲探法相比,B超引导下行臂丛神经阻滞麻醉的麻醉操作时间虽然有所延长,然而麻醉效果佳,能够缩短感觉阻滞起效时间、减少麻醉药物用量,且安全性好。  相似文献   
70.
笔者在标本解剖操作观察腋窝结构时发现1例左侧腋动脉与臂丛神经位置及走行出现变异,既往文献报道的变异多为腋动脉发出的分支与臂丛神经之间的位置与走行之间变异[1-3],本次解剖观察发现腋动脉与臂丛神经的内侧束、外侧束和后束之间的位置关系出现变异,与既往报道有所不同,现报告如下。  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