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   363篇
  免费   28篇
  国内免费   5篇
耳鼻咽喉   1篇
儿科学   27篇
妇产科学   3篇
基础医学   34篇
口腔科学   30篇
临床医学   42篇
内科学   72篇
皮肤病学   5篇
神经病学   15篇
特种医学   61篇
外科学   31篇
综合类   28篇
预防医学   18篇
药学   6篇
中国医学   4篇
肿瘤学   19篇
  2021年   9篇
  2020年   4篇
  2019年   3篇
  2018年   4篇
  2017年   6篇
  2016年   6篇
  2015年   9篇
  2014年   6篇
  2013年   17篇
  2012年   17篇
  2011年   13篇
  2010年   25篇
  2009年   12篇
  2008年   9篇
  2007年   6篇
  2006年   9篇
  2005年   8篇
  2004年   3篇
  2003年   3篇
  2002年   2篇
  2001年   2篇
  2000年   6篇
  1999年   3篇
  1998年   23篇
  1997年   15篇
  1996年   19篇
  1995年   8篇
  1994年   13篇
  1993年   10篇
  1992年   3篇
  1991年   8篇
  1990年   6篇
  1989年   11篇
  1988年   12篇
  1987年   15篇
  1986年   10篇
  1985年   6篇
  1984年   6篇
  1983年   3篇
  1982年   8篇
  1981年   2篇
  1980年   5篇
  1977年   3篇
  1976年   7篇
  1975年   2篇
  1971年   2篇
  1963年   2篇
  1958年   2篇
  1957年   4篇
  1955年   2篇
排序方式: 共有396条查询结果,搜索用时 21 毫秒
91.
目的 研究2种种植系统修复治疗后口腔健康相关生活质量(OHRQoL)的差异,为临床种植系统的选择和治疗效果的评估提供参考。方法 临床收集门诊且符合纳入标准的种植义齿修复患者100例,其中50例A组行安多健(Anthogry)种植系统修复,50例B组行士卓曼(Straumann)种植系统修复。采用口腔健康影响程度量表(OHIP-14)中文版作为测量方法研究2种种植系统修复6个月后患者OHRQoL的得分情况,比较两种种植系统修复后患者的OHRQoL的差异。结果 A组:"生理性疼痛"得分最高(P50=3.00),其次为"心理不适,心理障碍"(P50=2.00);"吃什么东西都不舒服"最常给牙列缺损患者带来负面影响。B组:"生理性疼痛"、"心理不适"、"生理障碍"三者得分最高(P50=2.00),其次为"心理障碍"(P50=1.5);"对自己的饮食很不满意"最常给牙列缺损患者带来负面影响。治疗后Anthogry与Straumann量表总得分差异无统计学意义(P>0.05)。结论 2种种植系统均能改善患者口腔健康状况,患者对两种系统的整体主观感受并无明显差异。  相似文献   
92.
Lithium augments GM-CSA generation in canine cyclic hematopoiesis   总被引:1,自引:0,他引:1  
Hammond  WP; Rodger  ER; Dale  DC 《Blood》1987,69(1):117-123
Cyclic hematopoiesis in gray collie dogs can be cured by lithium treatment. We examined the mechanism of lithium's effect by developing an assay for the canine equivalent of GM-CSF (called GM-CSA). Phytohemagglutinin (PHA)-stimulated canine blood mononuclear cells produce GM-CSA in a dose-dependent manner; this GM-CSA stimulates more neutrophil-containing colonies than does endotoxin-treated dog serum. Production of GM-CSA by PHA-stimulated normal dog cells was not altered by lithium. However, cells from gray collies during their neutrophilic period increased their GM-CSA when lithium (2 mEq/L) was added to low doses of PHA, whereas neutropenic gray collie cells did not. These data suggest that lithium could modulate cyclic hematopoiesis by increasing intramedullary GM-CSA at the time when marrow neutrophilic progenitor cells are at their nadir.  相似文献   
93.
Bang  A; Speck  ER; Blanchette  VS; Freedman  J; Semple  JW 《Blood》1996,88(8):2959-2966
Leukoreduced allogeneic platelet transfusions have been previously shown to initially stimulate an in vitro cellular cytotoxicity and subsequently Induce the formation of immunoglobulin G (IgG) antidonor alloantibodies. To further characterize these responses and determine if they are related, recipient BALB/c H-2d mice were treated with aminoguanidine (AMG), a selective inhibitor of inducible nitric oxide synthase (iNOS), and transfused weekly with 2 x 10(8) C57BL/6 H2b platelets. In control, non-AMG-treated mice, transfusion significantly (P < .01) increased serum levels of interferon-gamma (IFN-gamma) by day 1 posttransfusion (PT). IFN-gamma returned to pretransfusion levels by day 3 PT, and its production was not affected by AMG treatment. Serum interleukin-4 (IL-4), on the other hand, was undetectable before and during the transfusion protocol. By day 3 PT, recipient spleen cells could mediate in vitro anti-P815 (auto), anti-EL4 (allo), and anti-R1.1 (third-party MHC) cytotoxicity, and these responses were maximal by day 7 PT. Concurrently, a significant reduction in the vitro ability of recipient splenocytes to respond to Concanavalin A (ConA) was observed; this was not seen with lipopolysaccharide (LPS) stimulation. Elevated levels of NO2- were found in the ConA culture supernatants from transfused mice at day 3 PT. Serum antidonor alloantibodies were detected by the fifth platelet transfusion. AMG treatment of recipient mice significantly inhibited the transfusion. Induced cytotoxicity and ConA-stimulated NO2- production, and restored ConA-induced proliferation to normal levels. AMG appeared to selectively inhibit platelet-induced alloantibody production in that it did not affect antibody production induced by transfusions with 10(5) allogeneic leukocytes or by immunization with a foreign protein antigen, human gamma globulin, in adjuvant therapy. These results indicate that an in vivo AMG-sensitive mechanism is essential for recipients to initiate a humoral IgG immune response against allogeneic platelets.  相似文献   
94.
An abnormal increase in numbers of CCGG sites methylated in the 5' region of the human calcitonin (CT) gene occurred in tumor cell DNA samples from 90% (17 of 19) of patients with non-Hodgkin's T and B cell lymphoid neoplasms and in 95% (21 of 22) of tumor cell DNA samples from patients with acute nonlymphocytic leukemia (ANLL). The changes were not seen in patients with chronic myelogenous leukemia (0 of 9). The abnormal methylation patterns appear to be a property only of transformed or malignant cells since they were not found in DNA from nonneoplastic adult tissues including sperm, early myeloid progenitor cells, benign lymphoid hyperplasia, peripheral lymphocytes stimulated to divide, or early myeloid progenitor cells (obtained by immunoaffinity using anti-My-10 antibody), but they did appear after Epstein-Barr virus transformation of lymphocytes. Moreover, during the course of therapy in patients with ANLL, the hypermethylation pattern reflects the presence of the leukemic clone even in normal-appearing granulocytes derived from this clone. The increased methylation of the CT gene may then provide an important molecular marker for biologic events in human cell transformation or tumor progression and may prove clinically useful in monitoring patients with lymphoid and acute myelogenous neoplasms.  相似文献   
95.
Precursor B-cell acute lymphoblastic leukemias (B-ALLs) have been shown to be oligoclonal at the Ig heavy-chain (IgH) gene level in up to 40% of cases by Southern blot hybridization. In contrast, oligoclonality as deduced from diversity of T-cell receptor (TcR)-delta gene rearrangements of the immature types (ie, V delta 2-D delta 3, D delta 2-D delta 3) has not been reported, so far. We detected oligoclonality characterized by the coexistence of different junctional regions of identical V delta 2-D delta 3 rearrangements in four childhood precursor B-ALLs. No variation was found in the IgH gene status. Therefore, we define these populations as subclones. Two leukemias displayed the variants in an unequal proportion. In the other two leukemias, for which similar quantities of the coexisting rearrangements were detected, single cell-nuclei polymerase chain reaction (PCR) showed two separate leukemic populations. Subclone formation could not be demonstrated by Southern blot hybridization, but was detectable after PCR amplification of the V delta 2-D delta 3 rearrangement and separation by polyacrylamide gel electrophoresis. The variants arose independently from each other, as deduced from their individual sequences. Using subclone-specific oligonucleotides for hybridization to amplified DNA obtained at diagnosis and during follow- up from bone marrow samples, we demonstrate, (1) specificity of all subclone-deduced probes, (2) that one residual leukemic cell can be detected in 10(4) to 10(5) normal mononuclear cells in a semiquantitative assay, and (3) that none of the subclones persisted after induction therapy. We propose that in a leukemic cell population, TcR-delta gene diversity arises after rearrangements of the IgH genes resulting in apparent clonality at the IgH gene level. However, cells are oligoclonal, if the TcR-delta gene rearrangements are considered. As various subclones may respond differently to chemotherapy, they may hamper the detection of minimal residual disease. Therefore, we use all subclone-specific oligonucleotides for hybridization to amplified DNA from follow-up samples.  相似文献   
96.
Burns  ER; Zucker-Franklin  D 《Blood》1982,60(4):1030-1037
The pathologic hallmarks of thrombotic thrombocytopenic purpura (TTP) include endothelial cell proliferation and subendothelial hyalin deposits in the microvasculature leading to symptomatic thrombotic occlusions. Plasma or sera from three consecutive patients with TTP were subjected to multiple analyses to determine whether they induce endothelial injury and/or platelet activation, two pathogenic mechanisms that may account for this disorder. Sera were utilized in a microcytotoxicity assay against cultured human umbilical vein endothelial cells (EC). These cells were assessed ultrastructurally and with immunofluorescence techniques to ascertain the nature of inflicted cell damage. Control plasmas were obtained from healthy volunteers as well as patients with immune complex disease and the adult hemolytic uremic syndrome. In the presence of TTP serum, cell kill of 3H-proline- labeled EC averaged 42% versus 8.6% for control sera. Cytotoxicity induced by an IgG fraction of TTP sera averaged 70% versus 16.8% for control IgG. Removal of IgG by immune precipitation diminished cytotoxicity by 70%. Using indirect immunofluorescence, IgG was detected on EC incubated with TTP serum but not on EC treated with control serum. Ultrastructural changes became apparent within 30 min after exposure of cultured EC to TTP serum. Virtually every cell developed numerous cytoplasmic inclusions rarely seen in EC in the presence of normal serum. Prolonged incubation with the TTP serum led to progressive cytolysis, terminating with complete cytoplasmic and nuclear degeneration. Plasma from all three patients with TTP caused spontaneous aggregation of normal washed platelets as monitored by aggregometry. No spontaneous aggregation occurred in response to control plasmas. These results indicate that the sera of the three TTP patients studied were able to mediate time-dependent immune destruction of human cultured endothelial cells and that their plasmas were capable of causing spontaneous aggregation of normal human platelets in vitro. It would seem likely that these mechanisms are also operative in vivo to produce the endothelial destruction as well as the thrombotic vascular occlusions seen in this disorder.  相似文献   
97.
Burka  ER; Ballas  SK; Sabesin  SM 《Blood》1975,45(1):21-27
Exposure of rabbit or human erythrocytes to concentrations of puromycin as low as 7 x 10(-4)M for 2 hr causes damage to the cell membrane, as evidenced by increased susceptibility of the cells to hyposmotic lysis, increased cell rigidity, and ultrastructural changes consistent with severe membrane damage. Puromycin causes a concentration-dependent internalization of the erythrocyte membrane, resulting in vacuolization of the cells, at concentrations between 7 x 10(-4) M and 10(-2) M. Since the erythrocyte does not synthesize protein, the data indicate that puromycin has a direct toxic effect on erythroid cell membranes which is unrelated to its action in inhibiting the synthesis of protein.  相似文献   
98.
目的 研究唇腭裂患者AF-BF距和AXB角.方法 选取20例替牙期及30例恒牙期唇腭裂患者拍摄头颅定位侧位X线片,测量其AF-BF距及AXB角与北京市同龄、同性别正常儿童、青少年的AF-BF距及AXB角值进行比较.结果 替牙期和恒牙期唇腭裂患者AF-BF距及AXB角值无性别差异(P > 0.05).新疆地区替牙期和恒牙期唇腭裂患者AF-BF距小于北京市正常儿童、青少年(P < 0.05),而AXB角值差异无统计学意义(P > 0.05).结论 AF-BF距可以作为评价唇腭裂患者上下颌骨间矢状关系的指标之一,但最好进行综合分析.  相似文献   
99.
不育患者精索静脉曲张手术前后精液质量变化的观察   总被引:1,自引:0,他引:1  
目的:观察不育患者精索静脉曲张手术前后精液质量的变化,探讨手术的价值。方法:按WHO标准常规分析110例不育伴精索静脉曲张患者手术前后的精液质量。结果:110例精索静脉曲张患者术后精子密度、(A+B)级精子比率、有效精子数、精子活动率、活动精子数、精子低渗肿胀比率、正常形态精子比率较术前明显提高,两组差别有显著性意义(P0.05)。结论:精索静脉曲张手术能改善精液的质量。  相似文献   
100.
本文论述了分子筛制氧机的工作原理、主要组成部分及作用.强调了应严格遵守规章制度,认真做好制氧机的维护保养,加强质量监控和管理.同时阐述了医院在选购制氧系统时要综合分析影响其能耗的因素,在保证氧气产量和纯度的前提下,尽量降低系统能耗,提高长期运行的经济效益.  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