全文获取类型
收费全文 | 692篇 |
免费 | 48篇 |
专业分类
耳鼻咽喉 | 7篇 |
儿科学 | 10篇 |
妇产科学 | 9篇 |
基础医学 | 90篇 |
口腔科学 | 13篇 |
临床医学 | 113篇 |
内科学 | 82篇 |
皮肤病学 | 12篇 |
神经病学 | 35篇 |
特种医学 | 45篇 |
外科学 | 166篇 |
综合类 | 3篇 |
预防医学 | 43篇 |
眼科学 | 5篇 |
药学 | 28篇 |
肿瘤学 | 79篇 |
出版年
2021年 | 20篇 |
2020年 | 8篇 |
2019年 | 14篇 |
2018年 | 25篇 |
2017年 | 13篇 |
2016年 | 17篇 |
2015年 | 20篇 |
2014年 | 17篇 |
2013年 | 30篇 |
2012年 | 46篇 |
2011年 | 46篇 |
2010年 | 31篇 |
2009年 | 14篇 |
2008年 | 31篇 |
2007年 | 29篇 |
2006年 | 22篇 |
2005年 | 28篇 |
2004年 | 35篇 |
2003年 | 29篇 |
2002年 | 29篇 |
2001年 | 11篇 |
2000年 | 10篇 |
1999年 | 11篇 |
1997年 | 3篇 |
1995年 | 6篇 |
1994年 | 5篇 |
1993年 | 2篇 |
1992年 | 7篇 |
1991年 | 17篇 |
1990年 | 11篇 |
1989年 | 9篇 |
1988年 | 16篇 |
1987年 | 19篇 |
1986年 | 13篇 |
1985年 | 11篇 |
1984年 | 4篇 |
1983年 | 5篇 |
1980年 | 5篇 |
1979年 | 9篇 |
1978年 | 10篇 |
1977年 | 2篇 |
1976年 | 2篇 |
1975年 | 3篇 |
1974年 | 8篇 |
1973年 | 5篇 |
1972年 | 7篇 |
1971年 | 7篇 |
1970年 | 2篇 |
1969年 | 4篇 |
1968年 | 2篇 |
排序方式: 共有740条查询结果,搜索用时 15 毫秒
1.
R Lalloo N G Myburgh M J Smith G C Solanki 《Suid-Afrikaanse tydskrif vir geneeskunde》2004,94(8):639-642
OBJECTIVES: The first democratic government elected in South Africa in 1994 inherited huge inequities in health status and health provision across all sections of the population. This study set out to assess the impact of the new government's commitment to address these inequities and implement policies to improve population health in general and address inequalities in health care in particular. DESIGN: A 1998 household survey assessed many aspects of health delivery, including their own perceived and actual access to health care among different segments of South African society. RESULTS: Race was the main predictor of perceived changes in access to health care, with black, coloured-and Indian respondents significantly more likely to feel that access had improved since 1994, compared with white respondents. Socio-economic status (SES) was the main predictor of actual access to health care, with low and middle SES classes significantly less likely to access care when ill. CONCLUSIONS: One-third of respondents perceived health care access to have improved between 1994 and 1998, and this response was partially determined along racial lines. About one-quarter reported an inability to access health care when they required it, and this response was partially determined along socio-economic lines. This set of contrasting responses suggests that at a political level perceptions are largely influenced by race, but at the operational level actual access is influenced by SES. 相似文献
2.
A retrospective comparison of pyeloureterostomy and external ureteroneocystostomy as methods of reconstructing the urinary tract in 128 renal transplants is presented. There was one urological complication in 52 pyeloureterostomies (1.9%) compared with 4 in the 76 ureteroneocystostomies (5.3%). 6/0 Polydioxanone (PDS) is preferred to Prolene for the anastomosis because of possible calculus formation on the latter. Wound sepsis is commoner in pyeloureterostomies undergoing concomitant nephrectomy, despite prophylactic antibiotics, though this is not statistically significant and the overall sepsis rate is higher for ureteroneocystostomy. Nephrectomy was avoided in 17 selected cases by simply ligating the recipient ureter where the pre-transplant urine output was low. Two of these patients developed hydronephrosis in the isolated kidney and required later nephrectomy. 相似文献
3.
4.
Jansen Jacob G.; van Teijlingen Corrie M. M.; MOHN Georges R.; van Zeeland Albert A.; Vrieling Harry 《Mutagenesis》1994,9(5):417-421
Spectra of N-ethyl-N-nitrosourea (ENU)-induced mutations differwidely among various in vitro and in vivo mutational systems.To investigate possible reasons for these differences, a mutationalsystem is needed in which the same target gene is used for comparisonin the same type of cells in vitro and in vivo. In the presentstudy, this was achieved by analysing at the molecular level35 hprt mutant rat fibroblast clones obtained from cell populationsexposed in vitro to ENU and comparing the mutational spectrumwith the previously determined spectrum of ENU-induced hprtmutants in the same target cells exposed in vivo. Twenty-eightmutants contained a single base pair alteration in the hprtcoding sequence. Most of these changes were found at AT basepairs (19/28), the AT to TA transversion being the most frequentkind of mutation (12/19), which is probably caused by O2-ethylthymine.Transversions at AT base pairs showed all mutated T's to belocated in the nontranscribed strand of the hprt gene, suggestinga strand specific fixation of mutations induced by O2-ethylthymine,which appears to be a general feature of ENU- and ENNG-inducedhprt mutations in mammalian cells. GC to AT transitions, probablycaused by O6-ethylguanine, were detected at a lower frequency(7/28). This in vitro mutational spectrum was very similar tothat of the same target cells exposed in vivo to ENU. A comparisonof the mutational spectra in AGT-proficient and AGT-deficientrodent cells exposed to ethylating agents showed that in contrastto the situation in AGT-proficient rat fibroblasts, GC to ATbase pair changes (and not AT to TA) are the predominant mutationsin AGT-deficient hamster cells.
4To whom correspondence should be addressed 相似文献
5.
G. M. Randleff-Rasmussen M. M. J. Oosthuizen J. A. Myburgh 《Transplant international》1989,2(4):181-186
Various methods of determining cyclosporin (CyA) levels in patients after kidney transplantation were compared. These included
polyclonal antibody (pcAb-), specific and nonspecific monoclonal antibody (S- and NmcAb-) radioimmunoassays (RIA), and high
performance liquid chromatography (HPLC). The results obtained by the various methods when compared showed some correlation
but did not correspond. A probable explanation for part of this noncorrespondence is the presence of monoclonally crossreactive
metabolites (CyA-M). Another reason was that the concentration of CyA in the standards supplied with the RIA kits was found
to be higher than stated. 相似文献
6.
Sander D Borgsteede Corrie Graafland-Riedstra Luc Deliens Anneke L Francke Jacques ThM van Eijk Dick L Willems 《The British journal of general practice》2006,56(522):20-26
BACKGROUND: Most patients prefer to die at home, where a GP provides end-of-life care. A few previous studies have been directed at the GPs' values on good end-of-life care, yet no study combined values of patients and their own GP. AIM: To explore the aspects valued by both patients and GPs in end-of-life care at home, and to reflect upon the results in the context of future developments in primary care. DESIGN OF STUDY: Interviews with patients and their own GP. SETTING: Primary care in the Netherlands. METHOD: Qualitative, semi-structured interviews with 20 GPs and 30 of their patients with a life expectancy of less than 6 months, and cancer, heart failure or chronic obstructive pulmonary disease as underlying disease. RESULTS: Patients and GPs had comparable perceptions of good end-of-life care. Patients and GPs identified four core items that they valued in end-of-life care: availability of the GP for home visits and after office-hours, medical competence and cooperation with other professionals, attention and continuity of care. CONCLUSIONS: Future developments in the organisation of primary care such as the restriction of time for home visits, more part-time jobs and GP cooperatives responsible for care after office hours, may threaten valued aspects in end-of-life care. 相似文献
7.
Park JW Taube C Swasey C Kodama T Joetham A Balhorn A Takeda K Miyahara N Allen CB Dakhama A Kim SH Dinarello CA Gelfand EW 《American journal of respiratory cell and molecular biology》2004,30(6):830-836
The role of an interleukin (IL)-1 receptor antagonist (IL-1Ra) on the development of airway hyperresponsiveness (AHR) and airway inflammation following acute O(3) exposure in mice was investigated. Exposure of C57/BL6 mice to O(3) at a concentration of 2.0 ppm or filtered air for 3 h resulted in increases in airway responsiveness to inhaled methacholine (MCh) 8 and 16 h after the exposure, and an increase in neutrophils in the bronchoalveolar lavage (BAL) fluid. IL-1beta expression, assessed by gene microarray, was increased 2-fold 4 h after O(3) exposure, and returned to baseline levels by 24 h. Levels of IL-1beta in lung homogenates were also increased 8 h after O(3) exposure. Administration of (human) IL-1Ra before and after O(3) exposure prevented development of AHR and decreased BAL fluid neutrophilia. Increases in chemokine levels in lung homogenates, tumor necrosis factor-alpha, MIP-2, and keratinocyte chemoattractant following O(3) exposure were prevented by IL-1Ra. Inhalation of dexamethasone, an inhibitor of IL-1 production, blocked the development of AHR, BAL fluid neutrophilia, and decreased levels of IL-1 following O(3) exposure. In summary, acute exposure to O(3) induces AHR, neutrophilic inflammation, epithelial damage, and IL-1. An IL-1Ra effectively prevents the development of altered airway function, inflammation, and structural damage. 相似文献
8.
Fahlman A Jackson S Terblanche J Fisher JA Vesely A Sasano H Myburgh KH 《Respiratory physiology & neurobiology》2002,133(3):185-270
We report the development and testing of a simple breathing circuit that maintains isocapnia in human subjects during hypoxic hyperpnea. In addition, the circuit permits rapid switching between two gas mixtures with different partial pressures of oxygen. Eleven volunteers breathed repeated cycles of exposure to air (2 min of 21% O(2), balance N(2)) and hypoxia (2 min of 8.3+/-0.1% O(2), balance N(2)). Hypoxia induced significant increases in minute ventilation, breathing frequency and tidal volume (P < 0.05) that were consistent over repeated cycles of hypoxia (P > 0.1, one-way ANOVA). The system successfully maintained isocapnia in all subjects, with an average change in end-tidal CO(2) of only -0.2 mmHg during hyperventilation in hypoxia (range 0.4 to -0.8 mmHg). This system may be suitable for repeated tests of the hypoxic ventilatory response (HVR) and may prove useful for exploring intra- and inter-individual variability of HVR in humans. 相似文献
9.
Panayiotidis MI Rancourt RC Allen CB Riddle SR Schneider BK Ahmad S White CW 《Antioxidants & redox signaling》2004,6(1):129-136
The effect of hyperoxia on levels of DNA damage and global DNA methylation was examined in lung epithelial-like A549 cells. DNA damage was assessed by the single-cell gel electrophoresis (comet assay) and DNA methylation status by the cytosine extension assays. Cells exposed to ionizing radiation (0, 1, 2, 4, or 8 Gy) showed increasing rates of percentage of DNA in the tail and tail length with increasing radiation dose. When cells were exposed to room air (normoxia) for 1 day and 95% O2 (hyperoxia) for 1, 2, 3, 4, and 5 days, data indicated that hyperoxia caused time-dependent increases in levels of (a) single strand breaks, (b) double strand breaks, and (c) 8-oxoguanine. Decreased DNA methylation also was observed at day 5 of hyperoxic exposure, suggesting that hyperoxia-induced DNA damage can influence patterns of DNA methylation in a lung-derived cell line. 相似文献
10.
This study investigates the possibility that the active enhancing properties of bone marrow (BM) cells may be related to Ia-like determinants on their surface membranes. Less chromium was released on a cell per cell basis from nucleated baboon BM cells used as targets in complement-dependent cytotoxicity than from labelled lymph node lymphocytes. On the other hand, BM cells stimulated allogeneic lymphocytes in culture more vigorously than lymph node lymphocytes. BM cells with lymphocyte-activating properties could be enriched by fractionation on a discontinous bovine serum albumin gradietnt. BM cells responded poorly to allogeneic cell stimulation in mixed culture. Platelet absorption studies of an alloantiserum supported the conclusion that nucleated BM cells, and particularly BM fractions collected from the less dense interfaces of a bovine serum albumin gradient, express relatively more lymphocyte-activating or Ia-like determinants than "serologically defined" determinants. 相似文献