全文获取类型
收费全文 | 1676871篇 |
免费 | 126143篇 |
国内免费 | 2983篇 |
专业分类
耳鼻咽喉 | 24419篇 |
儿科学 | 46070篇 |
妇产科学 | 45269篇 |
基础医学 | 240460篇 |
口腔科学 | 50868篇 |
临床医学 | 146337篇 |
内科学 | 322950篇 |
皮肤病学 | 34229篇 |
神经病学 | 132183篇 |
特种医学 | 66578篇 |
外国民族医学 | 246篇 |
外科学 | 268368篇 |
综合类 | 39783篇 |
现状与发展 | 3篇 |
一般理论 | 475篇 |
预防医学 | 121599篇 |
眼科学 | 39506篇 |
药学 | 128472篇 |
3篇 | |
中国医学 | 3445篇 |
肿瘤学 | 94734篇 |
出版年
2018年 | 15218篇 |
2016年 | 13255篇 |
2015年 | 15368篇 |
2014年 | 21491篇 |
2013年 | 32095篇 |
2012年 | 43695篇 |
2011年 | 45711篇 |
2010年 | 26923篇 |
2009年 | 25525篇 |
2008年 | 44000篇 |
2007年 | 47005篇 |
2006年 | 47663篇 |
2005年 | 46212篇 |
2004年 | 45085篇 |
2003年 | 43427篇 |
2002年 | 42225篇 |
2001年 | 82911篇 |
2000年 | 85376篇 |
1999年 | 71650篇 |
1998年 | 18693篇 |
1997年 | 16765篇 |
1996年 | 16766篇 |
1995年 | 15754篇 |
1994年 | 14799篇 |
1993年 | 13740篇 |
1992年 | 57347篇 |
1991年 | 55447篇 |
1990年 | 54086篇 |
1989年 | 52653篇 |
1988年 | 48666篇 |
1987年 | 47604篇 |
1986年 | 44711篇 |
1985年 | 43112篇 |
1984年 | 32022篇 |
1983年 | 27289篇 |
1982年 | 15671篇 |
1981年 | 14063篇 |
1979年 | 30563篇 |
1978年 | 21280篇 |
1977年 | 18111篇 |
1976年 | 16187篇 |
1975年 | 17734篇 |
1974年 | 21827篇 |
1973年 | 20790篇 |
1972年 | 19747篇 |
1971年 | 18541篇 |
1970年 | 17676篇 |
1969年 | 17029篇 |
1968年 | 15330篇 |
1967年 | 14043篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
J Vandevoorde S Verbanck D Schuermans J Kartounian W Vincken 《The European respiratory journal》2006,27(2):378-383
The purpose of this study was to determine fixed cut-off points for forced expiratory volume in one second (FEV(1))/FEV(6) and FEV(6) as an alternative for FEV(1)/forced vital capacity (FVC) and FVC in the detection of obstructive and restrictive spirometric patterns, respectively. For the study, a total of 11,676 spirometric examinations, which took place on Caucasian subjects aged between 20-80 yrs, were analysed. Receiver-operator characteristic curves were used to determine the FEV(1)/FEV(6) ratio and FEV(6) value that corresponded to the optimal combination of sensitivity and specificity, compared with the commonly used fixed cut-off term for FEV(1)/FVC and FVC. The data from the current study indicate that FEV(1)/ FEV(6) <73% and FEV(6) <82% predicted can be used as a valid alternative for the FEV(1)/FVC <70% and FVC <80% pred cut-off points for the detection of obstruction and restriction, respectively. The statistical analysis demonstrated very good, overall, agreement between the two categorisation schemes. For the spirometric diagnosis of airway obstruction (prevalence of 45.9%), FEV(1)/FEV(6) sensitivity and specificity were 94.4 and 93.3%, respectively; the positive and negative predictive values were 92.2 and 95.2%, respectively. For the spirometric detection of a restrictive pattern (prevalence of 14.9%), FEV(6) sensitivity and specificity were 95.9 and 98.6%, respectively; the positive and negative predictive values were 92.2 and 99.3%, respectively. This study demonstrates that forced expiratory volume in one second/forced expiratory volume in six seconds <73% and forced expiratory volume in six seconds <82% predicted, can be used as valid alternatives to forced expiratory volume in one second/forced vital capacity <70% and forced vital capacity <80% predicted, as fixed cut-off terms for the detection of an obstructive or restrictive spirometric pattern in adults. 相似文献
32.
Published data devoted to making and characterization of the properties of polymeric wound dressings with proteolytic action
are reviewed. These data are indicative of individual dependence of the physicochemical properties, activity, and stability
of each particular enzyme on the type of polymer matrix and the method of immobilization. In order to obtain wound dressings,
which are active in physiological medium and retain their activity upon sterilization, it is necessary to optimize the composition
and characteristics of a polymer matrix and the enzyme included into its structure.
__________
Translated from Khimiko-Farmatsevticheskii Zhurnal, Vol. 40, No. 8, pp. 24–28, August, 2006. 相似文献
33.
Ohne Zusammenfassung 相似文献
34.
F Pitta T Troosters V S Probst M A Spruit M Decramer R Gosselink 《The European respiratory journal》2006,27(5):1040-1055
Accurate assessment of the amount and intensity of physical activity in daily life is considered very important due to the close relationship between physical activity level, health, disability and mortality. For this reason, assessment of physical activity in daily life has gained interest in recent years, especially in sedentary populations, such as patients with chronic obstructive pulmonary disease (COPD). The present article aims to compare and discuss the two kinds of instruments more commonly used to quantify the amount of physical activity performed by COPD patients in daily life: subjective methods (questionnaires, diaries) and motion sensors (electronic or mechanical methods). Their characteristics are summarised and evidence of their validity, reliability and sensitivity is discussed, when available. Subjective methods have practical value mainly in providing the patients' view on their performance in activities of daily living and functional status. However, care must be taken when using subjective methods to accurately quantify the amount of daily physical activity performed. More accurate information is likely to be available with motion sensors rather than questionnaires. The selection of which motion sensor to use for quantification of physical activity in daily life should depend mainly on the purpose of its use. 相似文献
35.
C T Gan G P McCann J T Marcus S A van Wolferen J W Twisk A Boonstra P E Postmus A Vonk-Noordegraaf 《The European respiratory journal》2006,28(6):1190-1194
The aim of the current study was to investigate whether alterations in N-terminal pro brain natriuretic peptide (NT-proBNP) reflect changes in right ventricular structure and function in pulmonary hypertension patients during treatment. The study consisted of 30 pulmonary hypertension patients; 15 newly diagnosed and 15 on long-term treatment. NT-proBNP, right heart catheterisation and cardiac magnetic resonance imaging measurements were performed, at baseline and follow-up. There were no significant differences between newly diagnosed patients and those on treatment at baseline or follow-up with respect to NT-proBNP, haemodynamics and right ventricular parameters. Relative changes in NT-proBNP during treatment were correlated to the relative changes in right ventricular end-diastolic volume index (r = 0.59), right ventricular mass index (r = 0.62) and right ventricular ejection fraction (r = -0.81). N-terminal pro brain natriuretic peptide measurements reflect changes in magnetic resonance imaging-measured right ventricular structure and function in pulmonary hypertension patients. An increase in N-terminal pro brain natriuretic peptide over time reflects right ventricular dilatation concomitant to hypertrophy and deterioration of systolic function. 相似文献
36.
37.
Antony E. Shrimpton Robert L. Schelper Reinhold P. Linke John Hardy Richard Crook Dennis W. Dickson Takashi Ishizawa Richard L. Davis 《Neuropathology》2007,27(3):228-232
Over 100 mutations in the presenilin‐1 gene (PSEN1) have been shown to result in familial early onset Alzheimer disease (EOAD), but only a relatively few give rise to plaques with an appearance like cotton wool (CWP) and/or spastic paraparesis (SP). A family with EOAD, seizures and CWP was investigated by neuropathological study and DNA sequencing of the PSEN1 gene. Aβ was identified in leptomeningeal vessels and in cerebral plaques. A single point mutation, p.L420R (g.1508T > G) that gives rise to a missense mutation in the eighth transmembrane (TM8) domain of PS1 was identified in two affected members of the family. p.L420R (g.1508T > G) is the mutation responsible for EOAD, seizures and CWP without SP in this family. 相似文献
38.
39.
T. Svara M. Gombac M. Vrecl P. Juntes R. Kostanjsek A. Pogacnik M. Pogacnik 《Transboundary and Emerging Diseases》2006,53(1):26-29
Clinicopathological and electron microscopical findings of eight cases of enzootic nasal adenocarcinoma of sheep, diagnosed solely in one big flock in Slovenia between years 2001 and 2003 are described. All affected sheep were female, their mean age was 4.5 ± 1.5 years and they either belonged to the Istrian pramenka breed (five sheep) or were crossbreeds (three sheep). Tumours that arose from the ethmoid area of the nasal cavity were unilateral in six cases (75%) and bilateral in two cases (25%). All tumours were classified as adenocarcinomas by histopathological examination and they displayed either a combination of tubular and papillary growth or less often solely tubular proliferation. No metastases were detected in regional lymph nodes, brain or other organs. Electron microscopical studies performed on the reprocessed paraffin‐embedded tissues revealed the presence of the virus‐like particles with an average diameter between 70 and 90 nm. 相似文献
40.