全文获取类型
收费全文 | 5132篇 |
免费 | 339篇 |
国内免费 | 16篇 |
专业分类
耳鼻咽喉 | 44篇 |
儿科学 | 101篇 |
妇产科学 | 62篇 |
基础医学 | 777篇 |
口腔科学 | 43篇 |
临床医学 | 505篇 |
内科学 | 1296篇 |
皮肤病学 | 36篇 |
神经病学 | 512篇 |
特种医学 | 277篇 |
外科学 | 839篇 |
综合类 | 15篇 |
一般理论 | 6篇 |
预防医学 | 285篇 |
眼科学 | 41篇 |
药学 | 312篇 |
中国医学 | 3篇 |
肿瘤学 | 333篇 |
出版年
2023年 | 44篇 |
2022年 | 86篇 |
2021年 | 220篇 |
2020年 | 98篇 |
2019年 | 160篇 |
2018年 | 199篇 |
2017年 | 133篇 |
2016年 | 146篇 |
2015年 | 156篇 |
2014年 | 226篇 |
2013年 | 286篇 |
2012年 | 420篇 |
2011年 | 428篇 |
2010年 | 220篇 |
2009年 | 199篇 |
2008年 | 296篇 |
2007年 | 292篇 |
2006年 | 239篇 |
2005年 | 222篇 |
2004年 | 163篇 |
2003年 | 171篇 |
2002年 | 130篇 |
2001年 | 73篇 |
2000年 | 70篇 |
1999年 | 62篇 |
1998年 | 30篇 |
1997年 | 18篇 |
1996年 | 19篇 |
1995年 | 31篇 |
1994年 | 17篇 |
1993年 | 17篇 |
1992年 | 56篇 |
1991年 | 48篇 |
1990年 | 63篇 |
1989年 | 50篇 |
1988年 | 40篇 |
1987年 | 36篇 |
1986年 | 35篇 |
1985年 | 36篇 |
1984年 | 23篇 |
1983年 | 24篇 |
1980年 | 16篇 |
1979年 | 21篇 |
1978年 | 15篇 |
1977年 | 14篇 |
1976年 | 11篇 |
1975年 | 13篇 |
1974年 | 14篇 |
1968年 | 11篇 |
1967年 | 12篇 |
排序方式: 共有5487条查询结果,搜索用时 15 毫秒
11.
12.
The purpose of this study was to evaluate the merits of the end expiratory lung volume as an indirect ventilatory index of bronchial obstruction and to show an application of continuous monitoring of lung volume in asthmatic patients. The accuracy of the external measurements (IS) of functional residual capacity (FRC) was controlled by comparing them with the helium measurements (DS) obtained during nine methacholine tests (IS = 0.06 + 1.065 DS in litres: R2 = 0.99). Seven asthmatics (18-48 yr) were monitored by measuring rib cage and abdominal perimeter variations. This was done in basal condition, after methacholine-induced bronchoconstriction and after bronchodilation by either salbutamol or oxytropium bromide inhalation. All the subjects were investigated on two separate days and were their own control. Bronchoconstriction produced a significant increase (p less than 0.01) of tidal volume (VT: + 67%), external minute ventilation (VE: + 58%), mean inspiratory flow (VT/TI: + 78%) and FRC (+ 26.5%) while frequency (f) and fractional inspiratory time (TI/TT) fluctuated non significantly. In the group of seven tested subjects, there was a significant correlation (p less than 0.01) between forced expiratory volume in one second (FEV1) and VE, FEV1 and VT/TI, FEV1 and FRC. However, the individual regression line showed a significant relationship only between FEV1 and FRC (R2 = 0.80 +/- 0.04). We therefore conclude that the variation of the end expiratory level can be chosen as an indirect index of bronchoconstriction.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
13.
Daniel Fagret Jean-Eric Wolf Paul Pilichowski Jean-Paul Mathieu Claude Pernin Marcel Apparu Charles Arvieux Pierre Cuchet Michel Vidal Michel Comet 《European journal of nuclear medicine and molecular imaging》1988,14(12):624-627
The myocardial uptake of fatty acids labeled with radioactive iodine and injected i.v. can only be evaluated with SPECT if their oxidation kinetics is slow enough. For this reason, we evaluated different iodomethylated fatty acids in mice and dogs to determine which of them shows the highest myocardial uptake and the slowest oxidation. The most suitable was found to be 16-iodo-3-methyl hexadecanoic acid (mono ) since its myocardial fixation was the same as that of the reference, i.e. 16-iodo-9-hexadecenoic acid (IHA), whereas it was degraded more slowly. Thirty min after injection of mono into dogs, the decrease in myocardial activity with respect to the maximum was two fold less than after IHA injection. The myocardial uptake of the two dimethylated fatty acids studied, i.e. 16-iodo-2,2-methyl hexadecanoic acid and 16-iodo-3,3-methyl hexadecanoic acid, was less than that of IHA in mice and dogs. In the latter, the myocardial uptake was so small that we were unable to study the time course of its activity. Consequently, these dimethylated fatty acids are not suitable for the study of the myocardial uptake of fatty acids in man. 相似文献
14.
15.
Cytosine methylation was studied at the level of the euchromatin/heterochromatin transition genomic region of the Arabidopsis chromosome 5 left arm. It has been shown using a monoclonal antibody against 5-methylcytosines that the density of DNA methylation
increases from the euchromatin towards the heterochromatin. YACs mapped along this region were characterized for their repeated
sequences content. Some of them, corresponding to euchromatin, euchromatin/heterochromatin border and heterochromatin regions,
were used as probes for a Southern blot analysis of methylation. This revealed that the degree of mCmCGG and GATmC methylation
increases significantly from the euchromatin towards the heterochromatin. Moreover, an analysis of cytosine methylation levels
(% of 5-methylcytosine) of different DNA fragments, inside the same genomic region, was performed using PCR and/or Southern
blot approaches. There is a gradual increase of methylation along the genomic region analyzed: CpG methylation in the euchromatic
fraction, CpG and CpNpG methylation at the euchromatin/heterochromatin transition and an additional asymmetrical methylation
in the repeated-heterochromatic fraction. The most methylated repeated family at CpG, CpNpG and asymmetrical sites is the
5S ribosomal DNA, highly methylated even though it is transcribed.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
16.
Goullé JP Lhermitte M Bartholi M Boyer JC Capolaghi B Charlier C Danel V Desch G Feuillu A Flouvat B Mathieu D Nisse P Sadeg N Szymanowicz A;Groupe de travail pluridisciplinaire SFBC-SFTA-STC < Toxicologie et biologie clinique > 《Annales de biologie clinique》2003,61(4):421-433
The members of the joint group "Toxicology and Clinical Biology" of the French Society of Clinical Biology (SFBC), the French Society of Analytical Toxicology (SFTA), and the Society of Clinical Toxicology (STC), suggest guidelines to meet the requirements of clinical biologists who are not specialized in toxicology. Based on good laboratory practice they propose a number of guidelines. Three synthetic tables have been established. They are not only toxicity biomarkers and metabolic disorders associated with the main severe intoxications, but also clinical signs that are observed during these intoxications, finally biological sampling as a precautionary measure. The table also takes into account approximately fifty xenobiotics: main clinical signs emergency, identification or quantification of the suspected product, useful biological markers, therapeutic, quantitations necessary to take into consideration patient care, and poison antidotes, are described. Recommendations regarding medical and forensic techniques are also proposed by the group. It is also necessary to collect and store biological samples when the individual patients are in charge. These samples will be analyzed or not depending on the individual case history. 相似文献
17.
To-Nga Dao Jean Mathieu Jean-Pierrs Bouchard Marc De Braekeleer 《Clinical genetics》1992,42(5):234-239
Myotonic dystrophy (MD) is an autosomal dominant disorder that has a high prevalence in Saguenay-Lac-St-Jean. A case-control study, based on a population register, of 373 MD patients who married in this region between 1855 and 1971 was conducted to determine whether their fertility was affected by the disorder. Six demographic parameters, that is the number of children, the age at marriage, the ages at the time of birth of the first and the last child, the interval between the marriage and the birth of the first child, and the interval between consecutive births, were analyzed. The mean number of children born to MD and control individuals was not different (P > 0.05). However, MD males had more children than MD females although they have started delaying their marriage since 1921. Fertility fell significantly in both the MD and control groups during the period of observation. This change reflects the decline in fertility of French Canadians in general during this period, but mainly after 1940. 相似文献
18.
Dynamic CT features of hepatic abscesses 总被引:31,自引:0,他引:31
Forty hepatic abscesses were examined with dynamic computed tomography (CT). A "double target sign," consisting of a hypodense central area surrounded by first a hyperdense ring and then a hypodense zone, seems to be highly suggestive of abscess formation. In 12 cases, the hepatic parenchyma surrounding the lesion demonstrated transient hyperdensity after contrast injection, possibly due to localized hepatic venous obstruction secondary to acute hepatic inflammation. This is similar to the appearance of an arterioportal fistula. 相似文献
19.
P Girard M Mathieu G Simonneau P Petitpretz J Cerrina P Herve J Rosso D Musset J Mensch P Duroux 《Thorax》1987,42(7):481-486
The risk of early recurrence of pulmonary embolism in patients with venous thromboembolic disease treated by anticoagulants is not well established. To determine the risk linked to contemporary proximal deep venous thrombosis, a prospective study was organised to give clinical and scintigraphic surveillance to 50 patients with angiographically proved pulmonary embolism plus phlebographically proved proximal deep vein thrombosis during the first 15 days of anticoagulant treatment. Perfusion lung scans were performed initially and on days 3, 7, and 15. Only two patients had a recurrence of pulmonary embolism during this period; both episodes were revealed by new symptoms, and one recurrence was fatal. The systematic performance of angiography in four patients found to have new scintigraphic defects led to the diagnosis of "spurious scintigraphic recurrence" in three of them. It is concluded that (a) adjusted anticoagulant treatment showed an effectiveness of 96% for preventing early recurrence of pulmonary embolism in this group of supposed high risk patients, and (b) in patients with recent pulmonary embolism new defects on systematic perfusion lung scans are not specific indicators of recurrent pulmonary embolism. 相似文献
20.
Prince Kevin Danieles Marina Ybarra Andraea Van Hulst Tracie A. Barnett Marie-Ève Mathieu Lisa Kakinami Olivier Drouin Jean-Luc Bigras Mélanie Henderson 《Obesity research & clinical practice》2021,15(2):157-162
IntroductionAttrition in pediatric weight management programs is notoriously high. Greater understanding of its determinants is needed to inform retention strategies. We identified determinants of attrition in CIRCUIT, a healthy lifestyle intervention program for youth at risk of cardiovascular disease.MethodsA one-arm intervention study of children aged 4-18 years who initiated the CIRCUIT program in the first five years of its existence (N = 403). We defined attrition as attending the baseline visit but ceasing attendance prior to the 1-year follow-up. Potential determinants of dropout included the child’s age, sex, ethnicity, body mass index (BMI) z-score, family socio-demographic characteristics, and estimated driving time to the program, all measured at baseline. Associations were estimated bivariately, using chi-squared- and t-tests, and simultaneously in a multivariable logistic regression model.ResultsOf the 403 participants who started the program, 198 (49%) dropped out within 12 months of enrollment. Youth who dropped out were older (mean age 12.8y vs. 11.3y; p < 0.01), were less likely to live with both parents (62% vs. 71%; p = 0.05), and to have mothers who had completed high school (79% vs. 88%; p = 0.01). No group differences were observed for sex, ethnicity, baseline BMI z-score, fathers’ education, or driving time to the program. In multivariate models, only older age at initiation of the intervention (OR: 1.2; CI: 1.1,1.3) and lower maternal education (OR: 2.0; CI: 1.0,3.8) were associated with dropout.ConclusionImproved tailoring of interventions to older pediatric participants and to families of lower maternal education may help reduce attrition in CIRCUIT and similar lifestyle intervention programs. 相似文献