全文获取类型
收费全文 | 741篇 |
免费 | 47篇 |
国内免费 | 12篇 |
专业分类
耳鼻咽喉 | 1篇 |
儿科学 | 3篇 |
妇产科学 | 3篇 |
基础医学 | 112篇 |
口腔科学 | 2篇 |
临床医学 | 31篇 |
内科学 | 90篇 |
皮肤病学 | 11篇 |
神经病学 | 40篇 |
特种医学 | 26篇 |
外国民族医学 | 1篇 |
外科学 | 52篇 |
综合类 | 51篇 |
预防医学 | 16篇 |
眼科学 | 6篇 |
药学 | 82篇 |
中国医学 | 33篇 |
肿瘤学 | 240篇 |
出版年
2023年 | 8篇 |
2022年 | 12篇 |
2021年 | 12篇 |
2020年 | 20篇 |
2019年 | 9篇 |
2018年 | 21篇 |
2017年 | 13篇 |
2016年 | 16篇 |
2015年 | 16篇 |
2014年 | 23篇 |
2013年 | 61篇 |
2012年 | 26篇 |
2011年 | 41篇 |
2010年 | 36篇 |
2009年 | 30篇 |
2008年 | 39篇 |
2007年 | 35篇 |
2006年 | 36篇 |
2005年 | 20篇 |
2004年 | 29篇 |
2003年 | 19篇 |
2002年 | 23篇 |
2001年 | 18篇 |
2000年 | 11篇 |
1999年 | 12篇 |
1998年 | 12篇 |
1997年 | 12篇 |
1996年 | 8篇 |
1995年 | 5篇 |
1994年 | 8篇 |
1993年 | 6篇 |
1992年 | 5篇 |
1991年 | 6篇 |
1990年 | 6篇 |
1988年 | 14篇 |
1987年 | 8篇 |
1986年 | 4篇 |
1985年 | 12篇 |
1984年 | 23篇 |
1983年 | 10篇 |
1982年 | 22篇 |
1981年 | 6篇 |
1980年 | 16篇 |
1979年 | 6篇 |
1978年 | 4篇 |
1977年 | 3篇 |
1975年 | 5篇 |
1973年 | 2篇 |
1972年 | 4篇 |
1970年 | 2篇 |
排序方式: 共有800条查询结果,搜索用时 15 毫秒
1.
AimsIn response to the COVID-19 pandemic, guidelines on reduced fractionation for patients treated with curative-intent radiotherapy were published, aimed at reducing the number of hospital attendances and potential exposure of vulnerable patients to minimise the risk of COVID-19 infection. We describe the changes that took place in the management of patients with stage I–III lung cancer from April to October 2020.Materials and methodsLung Radiotherapy during the COVID-19 Pandemic (COVID-RT Lung) is a prospective multicentre UK cohort study. The inclusion criteria were: patients with stage I–III lung cancer referred for and/or treated with radical radiotherapy between 2nd April and 2nd October 2020. Patients who had had a change in their management and those who continued with standard management were included. Data on demographics, COVID-19 diagnosis, diagnostic work-up, radiotherapy and systemic treatment were collected and reported as counts and percentages. Patient characteristics associated with a change in treatment were analysed using multivariable binary logistic regression.ResultsIn total, 1553 patients were included (median age 72 years, 49% female); 93 (12%) had a change to their diagnostic investigation and 528 (34%) had a change to their treatment from their centre's standard of care as a result of the COVID-19 pandemic. Age ≥70 years, male gender and stage III disease were associated with a change in treatment on multivariable analysis. Patients who had their treatment changed had a median of 15 fractions of radiotherapy compared with a median of 20 fractions in those who did not have their treatment changed. Low rates of COVID-19 infection were seen during or after radiotherapy, with only 21 patients (1.4%) developing the disease.ConclusionsThe COVID-19 pandemic resulted in changes to patient treatment in line with national recommendations. The main change was an increase in hypofractionation. Further work is ongoing to analyse the impact of these changes on patient outcomes. 相似文献
2.
食管癌三维适形后程加速超分割放射治疗的疗效分析 总被引:3,自引:0,他引:3
目的评价三维适形后程加速超分割放射治疗食管癌的疗效及放疗反应、并发症。方法2002年2月至2004年5月,71例食管鳞癌随机分成两组,三维适形后程加速超分割组36例,食管病变上下外约4cm,前后、左右外约0.5~1cm作为PTV1,每次2GY,每周5次,DT40GY后,病变上下外约2cm,前后、左右外约0.5~1cm作为PTV2,每日2次,每次1.5GY,间隔4~6小时,总疗程6周,总剂量67GY/38次。非三维适形后程加速超分割组35例,时间、剂量、分割方式同适形组。所有病例均采用8MV-X外照射。结果1、2、3年的生存率和原发肿瘤的局控率,与非适形后程加速超分割比较,适形组明显提高,分别为88.9%、75%、63.9%比68.6%、51.4%、40%和86.1%、72.2%、58.3%比65.7%、48.5%、34.3%。适形组的急性放射反应明显低于非适形后程加速超分割组,两组有显著差别。结论本研究的初步结果表明食管癌适形后程加速超分割放射治疗的疗效优于非适形后程加速超分割组。 相似文献
3.
J. Byström R. C. Garcia† L. Håkansson M. Karawajczyk L. Moberg J. Soukka‡ P. Venge 《Clinical and experimental allergy》2002,32(7):1082-1091
BACKGROUND: Eosinophil cationic protein (ECP) is an eosinophil-derived protein, which has been shown to be present in circulating neutrophils. OBJECTIVE: To establish whether ECP is produced or internalized by peripheral blood neutrophils. METHODS: This was done using microscopy, flow cytometry, fractionation of cells and RT-PCR techniques. RESULTS: No ECP mRNA was detected after extensive cell purification to eliminate all traces of contaminating eosinophils. Examination of immunostained neutrophils by light, confocal, electron microscopy together with cell fraction experiments, established that ECP is present intracellularly and is mostly associated to cell granules. Uptake studies by flow cytometry and by using both cold and radiolabelled ECP showed that it is internalized by neutrophils and stored in some proportion in their primary granules. Upon stimulation with serum-treated Sephadex particles, the internalized ECP was partially released from cells. CONCLUSION: ECP is not produced but can be internalized by circulating neutrophils, which take it from the environment and partially store it in their primary granules. 相似文献
4.
1992年10月以来,对21例类风湿性关节炎共进行了71人次血浆成分分离治疗(PF),平均1-2周内进行3.6人次,并在治疗前后进行总体评估。结果示:疗程完成后,全部病例的体力活动和实验室指标均有不同程度改善,3例活动受限者治疗后均能自由行走。平均每次分离血浆5731±129ml,其中IC,IgG,IgG,IgA,均有统计学意义的减少。血沉从80.21±34.00mm/h降到51.40±31.28mm/h,8例类风湿因于阳性的患者中,5例阴转,作者认为PF正在成为一种实用的技术,并可能是治疗类风湿关节炎最好的方法之一。 相似文献
5.
食管癌加速超分割放疗的临床研究 总被引:2,自引:0,他引:2
目的:评价加速超分割放射治疗食管癌的疗效。方法:食管鳞癌98例随机分为常规组和加速超分割组。常规组:180~200cGy/次,5次/周,总量6000~7000cGy/6~7周;加速超分割组:150cGy/次,2次/日,间隔6小时,总量5400cGy/35周。两组病人均采用60Co远距离外照射。结果:常规组1,3,5年生存率分别为46%(23/50)、20%(10/50)、12%(6/50);加速超分割组1,3,5年生存率分别为708%(34/48)、396%(19/48)、292%(14/48),加速超分割组明显优于常规组(P<005),而两组放疗反应和并发症无明显差异。结论:加速超分割放疗能明显提高食管癌病人的生存率,但不增加放疗反应及并发症。 相似文献
6.
A major allergen of Parietaria officinalis, a species responsible for a large number of respiratory allergies in Mediterranean areas, has been identified and characterized. This allergen (Pol) was found in the fraction which precipitates between 70 and 100% ammonium sulphate saturation. Pol showed a molecular weight of 15,000 daltons as determined by SDS-PAGE and HPLC. The pI of Pol was in the pH region 4-6, IEF showing four major bands. Two major bands were shown by CIE, CRIE and immunoblotting; major contaminants or aggregates were also revealed by the latter technique and by HPLC. Pol showed an allergic specific activity 2 times higher than the crude extract; moreover it was shown to be a major allergen since it inhibited 29 out of 30 sera from allergic patients sensitive to P. officinalis. 相似文献
7.
Madörin Maya van Hoogevest Peter Hilfiker Rolf Langwost Birgit Kresbach Gerhard M. Ehrat Markus Leuenberger Hans 《Pharmaceutical research》1997,14(12):1706-1712
Purpose. The applicability of Asymmetrical Flow Field-Flow Fractionation (Asymmetrical Flow FFF) as an alternative tool to examine the distribution of a lipophilic drug (N-Benzoyl-staurosporine) within human plasma protein fractions was investigated with respect to high separation speed and loss of material on surfaces due to adsorption.
Methods. Field-Flow Fractionation is defined as a group of pseudo-chromatographic separation methods, where compounds are separated under the influence of an externally applied force based on differences in their physicochemical properties. This method was used to separate human plasma in its protein fractions. The drug distribution in the fractions was investigated by monitoring the fractionated eluate for drug content by fluorescence spectroscopy.
Results. Human plasma was separated into human serum albumin (HSA), high density lipoprotein (HDL), 2-macroglobulin and low density lipoprotein (LDL) fractions in less than ten minutes. Calibration of the system and identification of the individual fractions was performed using commercially available protein reference standards. The influence of membrane type and carrier solution composition on the absolute recovery of N-Benzoyl-staurosporine and fluorescein-isothio-cyanate-albumin (FITC-albumin) was found to be quite significant. Both factors were optimized during the course of the investigations. N-Benzoyl-staurosporine was found to be enriched in the fraction containing HSA.
Conclusions. If experimental conditions are thoroughly selected and controlled to suppress drug and plasma protein adsorption at the separation membrane, Asymmetrical Flow FFF shows high recoveries and fast separation of human plasma proteins, and can be a reliable tool to characterize drug / plasma protein interactions. For analytical purposes it has the potential to rival established technologies like ultracentrifugation in terms of ease-of-use, precision, and separation time. 相似文献
8.
目的比较不同分割放射治疗骨转移癌患者的时间效应,评价不同分割放疗的止病疗效。材料与方法对1992年5月~1997年5月我院收治的123例骨转移癌患者分别给予常规分割组、超分割组及大剂量低分割组不同的放射治疗,观察各组姑息止痛的放疗有效率.结果放疗1周时,止痛有效率为5.41%、10.3%及65.2%;放疗结束时为70.3%、77.3%与77.3%;放疗结束后3个月为65.0%、67.6%及74.2%.经统计学分析发现放疗1周时大剂量低分割组止痛有效率与其它组比较有明显差异。结论大剂量低分割放疗止痛率高,疗效出现早,而放疗结束时及结束后3月3组止病率无差异。故在骨转移癌的放疗中可考虑采用先大剂量低分割放疗后继常规或超分割的放疗方式。 相似文献
9.
S L Tucker H D Thames 《International journal of radiation oncology, biology, physics》1983,9(9):1373-1383
Total radiation dose often can be increased without subsequent increases in the severity of tissue injury by using reduced doses per fraction. The flexure dose, df, is defined as the largest fractional dose for which further fractionation produces no significant change in the total dose required to reach a specified effect level. Thus, df is clinically relevant in that it represents the limit of effective dose fractionation. For those tissues in which injury reflects depletion of a critical proportion of target cells, the flexure dose is a measure of the extent of the initial, nearly linear portion of the dose-survival curve. More generally, the flexure dose is a measure of the extent of the initial, nearly linear portion of a dose-response curve in organized tissue, whatever its relationship to clonogenic target cells might be. Several quantitative expressions for df are derived. The characteristic common to these is that each defines the flexure dose as a multiple of the ratio alpha/beta of the parameters of the linear-quadratic model of cell survival or dose response, where the multiple is a measure of experimental or statistical resolution. These multiples tend to fall within a limited range, thereby defining the "region of flexure" via the inequality 0.05 (alpha/beta) less than or equal to df less than or equal to 0.15 (alpha/beta). Estimates of the region of flexure are presented for a variety of normal and neoplastic tissues. 相似文献
10.