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   688篇
  免费   26篇
  国内免费   47篇
耳鼻咽喉   2篇
儿科学   38篇
妇产科学   3篇
基础医学   61篇
口腔科学   11篇
临床医学   95篇
内科学   211篇
皮肤病学   20篇
神经病学   23篇
特种医学   145篇
外科学   24篇
综合类   24篇
预防医学   7篇
眼科学   5篇
药学   55篇
中国医学   3篇
肿瘤学   34篇
  2023年   2篇
  2021年   4篇
  2020年   3篇
  2019年   2篇
  2018年   4篇
  2017年   7篇
  2016年   4篇
  2015年   20篇
  2014年   16篇
  2013年   19篇
  2012年   8篇
  2011年   9篇
  2010年   29篇
  2009年   26篇
  2008年   11篇
  2007年   45篇
  2006年   12篇
  2005年   8篇
  2004年   8篇
  2003年   4篇
  2002年   18篇
  2001年   17篇
  2000年   7篇
  1999年   9篇
  1998年   45篇
  1997年   47篇
  1996年   55篇
  1995年   30篇
  1994年   31篇
  1993年   20篇
  1992年   9篇
  1991年   11篇
  1990年   8篇
  1989年   33篇
  1988年   27篇
  1987年   23篇
  1986年   22篇
  1985年   16篇
  1984年   14篇
  1983年   6篇
  1982年   15篇
  1981年   11篇
  1980年   14篇
  1979年   4篇
  1978年   5篇
  1977年   5篇
  1976年   6篇
  1975年   7篇
  1931年   1篇
  1925年   1篇
排序方式: 共有761条查询结果,搜索用时 15 毫秒
11.
背景目前已开展了对重性精神病患者进提供连续性服务的研究。目的探讨基层对有抑郁症风险患者提供连续性服务的水平,并与对心力衰竭患者的服务水平进行对比。方法采用抑郁症风险患者与心力衰竭患者对比的探索性研究。采用患者问卷评估服务的持续性,包含如下内容:(1)联系的服务提供者数(个人连续性);(2)诊所内服务提供者之间的合作(团队连续性)(6个项目,分数1~5分);(3)诊所外全科医师与服务提供者之间的合作(跨界连续性)(4个项目,分数1~5分)。结果大多数抑郁症风险患者在过去1年中寻遍整个服务提供界联系了几个服务提供者,曾遇到过高水平团队连续性服务及低水平跨界连续性服务。在诊所中可接触到的不同服务提供者要明显多于心力衰竭患者服务提供者(P<0.01)。抑郁症风险患者的服务提供者之间的合作更好一些,每项平均得分4.3分,心力衰竭患者得分为4.0分(P=0.03)。然而,跨界连续性服务方面正好相反:抑郁症风险患者每项平均得分3.5分,心力衰竭患者得分为4.0分(P=0.01)。结论抑郁症风险患者与心力衰竭患者之间的探索性对比显示:体验服务连续性方面的差距不大。对此还应行进一步分析。  相似文献   
12.
Dopaminergic hyperfunction and N-methyl-D-aspartate receptor (NMDAR) hypofunction have both been implicated in psychosis. Dopamine-releasing drugs and NMDAR antagonists replicate symptoms associated with psychosis in healthy humans and exacerbate symptoms in patients with schizophrenia. Though hippocampal dysfunction contributes to psychosis, the impact of NMDAR hypofunction on hippocampal plasticity remains poorly understood. Here, we used an NMDAR antagonist rodent model of psychosis to investigate hippocampal long-term potentiation (LTP). We found that single systemic NMDAR antagonism results in a region-specific, presynaptic LTP at hippocampal CA1-subiculum synapses that is induced by activation of D1/D5 dopamine receptors and modulated by L-type voltage-gated Ca2+ channels. Thereby, our findings may provide a cellular mechanism how NMDAR antagonism can lead to an enhanced hippocampal output causing activation of the hippocampus-ventral tegmental area-loop and overdrive of the dopamine system.  相似文献   
13.
14.
15.
Plasma levels of plasminogen activator inhibitor type-1 (PAI-1), beta- thromboglobulin (beta TG), and fibrinopeptide A (FPA) were followed over 24 hours in 30 patients treated with alteplase for acute myocardial infarction. Samples were taken at baseline (T Oh), after 90 minutes (under alteplase, no heparin, T 1.5h), after 120 minutes (under alteplase and heparin, T 2h), 30 minutes after thrombolytic therapy (T 3.5h), as well as 12 hours (T 12h) and 24 hours (T 24h) after baseline. PAI-1 antigen levels (55 +/- 9 ng/mL at T Oh, mean +/- SEM) decreased to 35 +/- 5 (T 1.5h) and 40 +/- 6 (T 2h) ng/mL under alteplase, before increasing to 84 +/- 22 (T 3.5h), 130 +/- 30 (T 12h), and 64 +/- 7 (T 24h) ng/mL after therapy, P less than .001. A high baseline PAI-1 activity (18 +/- 3 ng/mL) decreased to 2.0 +/- 0.4 (T 1.5h) and 1.7 +/- 0.2 (T 2h) under alteplase and increased to 32 +/- 5 (T 12h) and 19 +/- 3 (T 24h) ng/mL after therapy (P less than .0001). beta TG levels (339 +/- 105 ng/mL at T Oh) decreased to 203 +/- 48 (T 2h), 154 +/- 51 (T 3.5h), 187 +/- 40 (T 12h), and 142 +/- 32 (T 24h) ng/mL under heparin (P less than .01). FPA levels (34 +/- 9 ng/mL at T Oh) increased to 85 +/- 15 ng/mL under alteplase alone (T 1.5h) and normalized under heparin (11 +/- 4, 6 +/- 2, 4 +/- 2, and 3 +/- 1 ng/mL at T 2h, T 3.5h, T 12h, and T 24h, respectively). A high level of FPA at T 3.5h correlated with reocclusion (33 +/- 12 ng/mL, n = 4 v 2.9 +/- 0.5 ng/mL, n = 21, P less than .005). We conclude that plasma levels of PAI- 1 antigen as well as activity markedly increase after alteplase therapy of acute myocardial infarction. The high activity of PAI-1 and decreasing beta TG levels suggest that platelets do not contribute significantly to this phenomenon. The marked increase of FPA levels under recombinant tissue-type plasminogen activator alone and its normalization under heparin emphasize the important role of concomitant anticoagulation in controlling further intravasal fibrin generation under alteplase.  相似文献   
16.
Previous studies found that bone marrow (BM) allografts from DLA- identical littermates resulted in survival of two thirds of recipient dogs after otherwise lethal doses of 450 to 600 cGy of total body irradiation (TBI) because of successful allografts or autologous recovery after rejection of the allografts. The current study asked whether survival could be further improved by treating allograft recipients with recombinant canine granulocyte colony-stimulating factor (G-CSF), stem cell factor (SCF), or G-CSF/SCF. Of 21 dogs, 14 (67%) receiving allografts but no growth factors survived, 10 with successful allografts (including 5 mixed chimeras) and 4 with autologous recovery; whereas 7 animals died, 5 from infections during BM aplasia and 2 from acute graft-versus-host disease. By comparison, 30 of 34 dogs (88%) receiving hematopoietic growth factors in addition to the BM graft survived, 17 with successful allografts (including 10 mixed chimeras) and 13 with autologous recovery; whereas 4 died, all with infection related to BM aplasia after rejection of the allograft. Survival was similar for recipients of G-CSF, SCF, or the combination of G-CSF and SCF. Logistic regression analyses, which accounted for possible effects of TBI dose, showed a trend for improved survival in dogs receiving growth factors (P = .09), no change in allogeneic engraftment (P = .74), and a slight increase in autologous recovery (P = .22). In agreement with previous data, we found that grafts of BM from DLA-identical littermates improved survival of recipient dogs exposed to low but otherwise lethal doses of TBI. A further improvement in survival could be achieved by additional treatment with G-CSF, SCF, or G-CSF/SCF. Results suggest that treatment by hematopoietic growth factors along with BM grafts should be considered for victims of radiation accidents.  相似文献   
17.
An immunoglobulin M (IgM)-positive cell line, Ms 28, apparently spontaneously transformed by Epstein-Barr virus (EBV) was established from peripheral blood cells of a patient with immature myeloblastic leukemia. It has been characterized according to phenotype, cytochemistry, and membrane antigen pattern. The cell line expresses lymphoid markers like CD 19, CD 22, and CD 30 and synthesizes and secretes IgM. Monocyte markers CD 11c, CD 14, and CD 15 are absent. Neither interleukin-1 (IL-1), nor tumor necrosis factor (TNF-alpha) are produced. But Ms 28 cells show strong phagocytic activity and engulf Latex particles and sheep RBCs (SRBCs) that need not to be opsonized. The phagocytic activity can be inhibited by chloroquine. Both phagocytosis and EBV nuclear-antigen (EBNA) expression can be observed in one and the same cell. Ms 28 cells might be useful to study immunologic activities like antigen processing and presentation.  相似文献   
18.
Conventional high‐grade osteosarcoma is the most common primary bone sarcoma, with relatively high incidence in young people. In this study we found that expression of Aven correlates inversely with metastasis‐free survival in osteosarcoma patients and is increased in metastases compared to primary tumours. Aven is an adaptor protein that has been implicated in anti‐apoptotic signalling and serves as an oncoprotein in acute lymphoblastic leukaemia. In osteosarcoma cells, silencing Aven triggered G2 cell‐cycle arrest; Chk1 protein levels were attenuated and ATR–Chk1 DNA damage response signalling in response to chemotherapy was abolished in Aven‐depleted osteosarcoma cells, while ATM, Chk2 and p53 activation remained intact. Osteosarcoma is notoriously difficult to treat with standard chemotherapy, and we examined whether pharmacological inhibition of the Aven‐controlled ATR–Chk1 response could sensitize osteosarcoma cells to genotoxic compounds. Indeed, pharmacological inhibitors targeting Chk1/Chk2 or those selective for Chk1 synergized with standard chemotherapy in 2D cultures. Likewise, in 3D extracellular matrix‐embedded cultures, Chk1 inhibition led to effective sensitization to chemotherapy. Together, these findings implicate Aven in ATR–Chk1 signalling and point towards Chk1 inhibition as a strategy to sensitize human osteosarcomas to chemotherapy. Copyright © 2015 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.  相似文献   
19.
目的:探索可早期预测严重败血症病人死亡的临床和实验室指标或系统模型。方法:对ICU连续收治的26例严重败血症病人行前瞻性观察28天,分析其死亡的相关临床和实验室指标。结果:共有14人(54%)死亡,多死于第1周内(74%)。根据循环中的细胞间粘附分子-1水平能早期预测其脏器衰竭和死亡。一些临床指标水平在死亡病人与生存病人之间差别较大,其中包括血总胆红素、pH值、红细胞压积、氧合指数、动静脉血氧差、四项SIRS指标和一些血流动力学指标等。结论:综合上述指标可以尝试建立起了一个能够早期评估病人死亡可能性的积分系统。  相似文献   
20.
背景和目的:最近的研究结果表明,对其他一线药物和注射类药物(如卡那霉素、卷曲霉素)等耐药是影响耐多药结核病(MDR-TB)患者治疗效果的独立危险因素.本研究旨在明确耐其他一线药物和注射类药物对韩国不合并人免疫缺陷病毒(HIV)感染的MDR-TB患者临床疗效的影响.方法:采用回顾性队列研究分析1996年1月至2005年12月首尔国家大学附属医院治疗的211例MDR-TB患者治疗效果,排除7例丢失和7例迁出,对197例患者进行了最终分析.  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