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   82篇
  免费   1篇
儿科学   9篇
基础医学   7篇
口腔科学   1篇
临床医学   8篇
内科学   22篇
皮肤病学   3篇
神经病学   5篇
外科学   5篇
综合类   1篇
药学   10篇
肿瘤学   12篇
  2017年   1篇
  2016年   1篇
  2012年   2篇
  2010年   5篇
  2009年   2篇
  2008年   1篇
  2006年   7篇
  2005年   1篇
  2004年   2篇
  2003年   2篇
  2002年   2篇
  1998年   5篇
  1997年   6篇
  1996年   3篇
  1995年   5篇
  1994年   5篇
  1993年   3篇
  1992年   1篇
  1987年   1篇
  1986年   3篇
  1985年   3篇
  1979年   3篇
  1977年   1篇
  1975年   1篇
  1973年   1篇
  1972年   1篇
  1970年   2篇
  1969年   1篇
  1965年   1篇
  1964年   2篇
  1963年   1篇
  1960年   1篇
  1958年   2篇
  1957年   2篇
  1955年   3篇
排序方式: 共有83条查询结果,搜索用时 15 毫秒
1.
Eight cultured cell lines were established from human smallcell lung cancers. Every cell line showed the morphologicaland biochemical characteristics of small cell cancer. Changesin cell characteristics were observed in many of these celllines when culture conditions were changed: "oat cell type"changed to "intermediate cell type" and vice versa when serum-freemedium was changed to serum-supplemented medium; a deficiencyof vitamin A in the medium caused a change to squamous cellsand vice versa; and a tumor promoter (teleocidin B) enhancedthe adherence of these cells to the surface of plastic culturedishes. These findings provide evidence that many small celllung cancer cell lines can change their morphology with changesin the environment of the cells.  相似文献   
2.
3.
Aim: The Center of Excellence for the Creation and Dissemination of a New Japanese Nursing Science at Chiba University School of Nursing is now in its third year of operation. This center aims to develop nursing science that is appropriate for Japanese culture and to internationally disseminate the importance of culturally based care. Our project seeks to systematically transform the art of nursing practise into a nursing science. Method: To date, multiple frameworks have been created through the qualitative meta‐synthesis of research on effective nursing care. To create a nursing science, these frameworks derived from meta‐synthesis must be verified and internalized in nursing practise. Results: After three years of research, the following findings are emerging: professional care relationships in nursing practise in Japan are characterized by the bidirectional process between the nurse and the client, in which both gradually undergo a transformation in order to establish a collaborative, therapeutic relationship; Japanese nurses emphasize the importance of understanding adolescent clients’ subjective understanding of their own life with self‐care, as well as social support; and the priority for community health nurses in Japan is to create support systems in the community, regardless of whether the intended client is an individual, a family, a specific group, or the community as a whole. Conclusions: Our future efforts will focus on verifying our findings through interdisciplinary and international comparative research and by integrating various frameworks in order to create a new Japanese nursing science.  相似文献   
4.
Unipolar Characteristics of CFAEs. Background: The noncontact mapping (NCM) system possesses the merit of global endocardial recording for unipolar and activation mapping. Objective: We aimed to evaluate the unipolar electrogram characteristics and activation pattern over the bipolar complex fractionated atrial electrogram (CFAE) sites during atrial fibrillation (AF). Methods: Twenty patients (age 55 ± 11 years old, 15 males) who underwent NCM and ablation of AF (paroxysmal/persistent = 13/7) were included. Both contact bipolar (32–300 Hz) and NCM virtual unipolar electrograms (0.5–300 Hz) were simultaneously recorded along with the activation pattern (total 223 sites, 11 ± 4 sites/patient). A CFAE was defined as a mean bipolar cycle length of ≤ 120 ms with an intervening isoelectric interval of more than 50 ms (Group 1A, n = 63, rapid repetitive CFAEs) or continuous fractionated activity (Group 1B, n = 59, continuous fractionated CFAEs), measured over a 7.2‐second duration. Group 2 consisted of those with a bipolar cycle length of more than 120 ms (n = 101). Results: The Group 1A CFAE sites exhibited a shorter unipolar electrogram cycle length (129 ± 11 vs 164 ± 20 ms, P < 0.001), and higher percentage of an S‐wave predominant pattern (QS or rS wave, 63 ± 13% vs 35 ± 13%, P < 0.001) than the Group 2 non‐CFAE sites. There was a linear correlation between the bipolar and unipolar cycle lengths (P < 0.001, R = 0.87). Most of the Group 1A CFAEs were located over arrhythmogenic pulmonary vein ostia or nonpulmonary vein ectopy with repetitive activations from those ectopies (62%) or the pivot points of the turning wavefronts (21%), whereas the Group 1B CFAEs exhibited a passive activation (44%) or slow conduction (31%). Conclusions: The bipolar repetitive and continuous fractionated CFAEs represented different activation patterns. The former was associated with an S wave predominant unipolar morphology which may represent an important focus for maintaining AF. (J Cardiovasc Electrophysiol, Vol. 21, pp. 640‐648, June 2010)  相似文献   
5.
Aim: Hydrogen peroxide (H2O2) is produced during liver transplantation. Ischemia/reperfusion induces oxidation and causes intracellular Ca^2+ overload, which harms liver cells. Our goal was to determine the precise mechanisms of these processes. Methods: Hepatocytes were extracted from rats. Intracellular Ca^2+ concentrations ([Ca^2+]i), inner mitochondrial membrane potentials and NAD(P)H levels were measured using fluorescence imaging. Phospholipase C (PLC) activity was detected using exogenous PIP2. ATP concentrations were measured using the luciferin-luciferase method. Patch-clamp recordings were performed to evaluate membrane currents.
Results: H2O2 increased intracellular Ca^2+ concentrations ([Ca^2+]i) across two kinetic phases. A low concentration (400 μmol/L) of H2O2 induced a sustained elevation of [Ca^2+]i that was reversed by removing extracellular Ca^2+. H2O2 increased membrane currents consistent with intracellular ATP concentrations. The non-selective ATP-sensitive cation channel blocker amiloride inhibited HRO2-induced membrane current increases and [Ca^2+]i elevation. A high concentration (1 mmol/L) of H2O2 induced an additional transient elevation of [Ca^2+]i, which was abolished by the specific PLC blocker U73122 but was not eliminated by removal of extracellular Ca^2+. PLC activity was increased by 1 mmol/L H2O2but not by 400 μmol/L H2O2.
Conclusions: H2O2 mobilizes Ca^2+ through two distinct mechanisms. In one, 400 μmol/L H2O2-induced sustained [Ca^2+]i elevation is mediated via a Ca^2+ influx mechanism, under which H2O2 impairs mitochondrial function via oxidative stress, reduces intracellular ATP production, and in turn opens ATP-sensitive, non-specific cation channels, leading to Ca^2+ influx. In contrast, 1 mmol/L H2O2-induced transient elevation of [Ca^2+]i is mediated via activation of the PLC signaling pathway and subsequently, by mobilization of Ca^2+ from intracellular Ca^2+ stores.  相似文献   
6.
A strategy for the synthesis of peptides and oligomeric proteins designed to form transmembrane ion channels is described. A folding motif that exhibits a functional ionic pore encompasses amphipathic α-helices organized as a four-helix bundle around a central hydrophilic pore. The channel-forming activity of monomeric amphipathic peptides may be examined after reconstitution in lipid bilayers in which peptides self-assemble into conductive oligomers. The covalent attachment of channel-forming peptides to the lysine ε-amino groups of a template molecule (KKKPGKEKG) specifies oligomeric number and facilitates the study of ionic permeation and channel blockade. Here we describe detailed protocols for the total synthesis of peptides and template-assembled four-helix bundle proteins, exemplified with the sequence of M2δ (EKM-STAISVLLAQAVFLLLTSQR), considered involved in lining the pore of the nicotinic acetylcholine receptor channel. For comparison, the synthesis of a second four-helix bundle, T4CaIVS3 with the sequence of predicted transmembrane segment S3 (DPWNVFDFLIVIGSIIDVILSE) of the fourth repeat of the l -type voltage-gated calcium channel, is included. Peptides and proteins are synthesized step-wise by solid-phase methods, purified by reversed-phase HPLC, and homogeneity ascertained by analytical HPLC, capillary zone electrophoresis, SDS/PAGE, amino acid analysis and sequencing. Optimization of synthetic procedures for hydrophobic molecules include reducing resin substitution to avoid steric hindrance and aggregation of the final product. Protocols for the preparation of the samples prior to HPLC purification as well as the conditions and columns required for successful purification are presented. The methods developed are generally applicable for the chemical synthesis, purification and characterization of amphipathic peptides and template directed helical bundle proteins.  相似文献   
7.
To investigate the relationship of Epstein-Barr virus (EBV) and angioimmunoblastic lymphadenopathy with dysproteinemia, we performed DNA analysis using the polymerase chain reaction (PCR), Southern blot, in situ hybridization, and immunohistochemical analysis of lymph nodes in five patients who were followed up and biopsied more than once. In the course of the disease, nodal architecture diminished, cellular atypia worsened, and clear cells increased in number. In the DNA analysis of the receptor genes, the clonal population increased in number. EBV nucleic acid sequences were found by either PCR or in situ hybridization in all examined nodes. The number of EBV-positive cells varied widely among the cases and throughout the course of the disease in the same patients. The analysis of EBV terminal repeats or lymphocyte-determined membrane antigen genes showed polyclonal populations of EB-infected cells. EBV-positive cells possessed intermediate- to large-sized nuclei, and the cells with large nuclei, especially, expressed latent membrane protein of EBV. These large cells varied in number among the cases. Double-labelling immunohistochemistry/in situ hybridization studies demonstrated that most of the EBV-positive cells expressed B-cell antigen (CD20). The presence of EBV seems to be associated with the selective defects of the immune system, rather than with the direct pathogenesis of angioimmunoblastic lymphadenopathy.  相似文献   
8.
Abstract As a part of an epidemiologic survey of dementia in a community of aged persons, correlation between sleep complaints and physical illness and senility were studied. A total of 3302 randomly sampled aged individuals (aged 65 yean) were studied using a questionnaire. In this sample the prevalence of poor sleep and habitual snoring did not increase with age. The prevalence of excessive daytime sleepiness showed an increase with age. Male predominance of habitual snoring and female predominance of poor sleep were observed. Female predominance of excessive daytime sleepiness was noted among the aged 70 and over. Age-related excessive daytime sleepiness was significantly correlated with senility.  相似文献   
9.
A 66-year-old female with liver cirrhosis was treated by transcatheter arterial embolization (TAE) for a small hepatocellular carcinoma. She developed steatonecrosis with tenderness which occurred in the upper abdomen after TAE. The hepatic falciform artery from the middle hepatic artery was detected by arteriography. Necrosis in the upper abdomen was considered to be due to ischaemic changes caused by micromaterials for embolization of this artery, injuries of hepatic arterial endothelia slowly caused by carcinostatics, and chemotoxicity. It was considered that such complication as observed in this patient should be taken into consideration when performing TAE.  相似文献   
10.
1. The intravenous injection of I131-labeled heterologous anti-leukocyte and anti-bone marrow antibodies into rats resulted in a high specific in vivolocalization in the bone marrow, indicating the presence of localizing anti-body.

2. No in vivo localization in lungs was demonstrated, in possible contrastto the earlier concept of pulmonary emboli of clumped leukocytes sensitizedwith antibodies in experimental immunoleukopenia.

3. Heterologous anti-leukocyte and anti-bone marrow antibodies injectedintravenously disappeared from plasma and fixed to peripheral leukocytesand bone marrow cells within 1 hour.

Submitted on June 25, 1962 Accepted on December 24, 1962  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