全文获取类型
收费全文 | 40986篇 |
免费 | 3471篇 |
国内免费 | 1230篇 |
专业分类
耳鼻咽喉 | 51篇 |
儿科学 | 1344篇 |
妇产科学 | 201篇 |
基础医学 | 2552篇 |
口腔科学 | 62篇 |
临床医学 | 5647篇 |
内科学 | 13071篇 |
皮肤病学 | 77篇 |
神经病学 | 480篇 |
特种医学 | 1850篇 |
外国民族医学 | 7篇 |
外科学 | 2859篇 |
综合类 | 8430篇 |
现状与发展 | 2篇 |
预防医学 | 2148篇 |
眼科学 | 26篇 |
药学 | 4101篇 |
45篇 | |
中国医学 | 1831篇 |
肿瘤学 | 903篇 |
出版年
2024年 | 157篇 |
2023年 | 695篇 |
2022年 | 1325篇 |
2021年 | 1890篇 |
2020年 | 1901篇 |
2019年 | 1613篇 |
2018年 | 1585篇 |
2017年 | 1689篇 |
2016年 | 1754篇 |
2015年 | 1687篇 |
2014年 | 3024篇 |
2013年 | 3247篇 |
2012年 | 2598篇 |
2011年 | 2652篇 |
2010年 | 2141篇 |
2009年 | 1926篇 |
2008年 | 1796篇 |
2007年 | 1794篇 |
2006年 | 1621篇 |
2005年 | 1418篇 |
2004年 | 1172篇 |
2003年 | 1021篇 |
2002年 | 834篇 |
2001年 | 743篇 |
2000年 | 641篇 |
1999年 | 553篇 |
1998年 | 455篇 |
1997年 | 451篇 |
1996年 | 455篇 |
1995年 | 365篇 |
1994年 | 335篇 |
1993年 | 258篇 |
1992年 | 254篇 |
1991年 | 202篇 |
1990年 | 195篇 |
1989年 | 157篇 |
1988年 | 142篇 |
1987年 | 129篇 |
1986年 | 112篇 |
1985年 | 150篇 |
1984年 | 133篇 |
1983年 | 69篇 |
1982年 | 71篇 |
1981年 | 58篇 |
1980年 | 55篇 |
1979年 | 40篇 |
1978年 | 29篇 |
1977年 | 27篇 |
1976年 | 23篇 |
1975年 | 15篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
21.
COPD机械通气病人下呼吸道感染致病菌分布特点 总被引:1,自引:0,他引:1
①目的 探讨慢性阻塞性肺病(COPD)病人机械通气后下呼吸道感染致病菌的特点。②方法 取32例COPD并发呼吸衰竭行机械通气病人下呼吸道分泌物做痰细菌学培养,同时做药物敏感试验。③结果 32例病人共分离出菌株76株,阳性率71.7%,其中混合感染10例次。其中革兰阴性杆菌(GNB)58株,占76.3%;阳性球菌10株,占13.2%;真菌8株,占10.5%。常见致病菌以铜绿假单胞菌、鲍曼不动杆菌和肺炎杆菌为主,GNB中铜绿假单胞菌和不动杆菌的耐药率高。④结论 COPD应用机械通气病人下呼吸道感染以革兰阴性杆菌为主,耐药性高。 相似文献
22.
Steven Elia Peter Liu Carol Chrusciel Alan Hilgenberg Charrisios Skourtis Demetrios Lappas 《Journal canadien d'anesthésie》1989,36(1):2-8
Global coronary blood flow and metabolism were measured in seven patients on the first postoperative day following coronary
revascularization to test the hypothesis that tracheal extubation produces adverse haemodynamic responses akin to those observed
during tracheal intubation. Regional coronary flow and metabolic measurements were made in five of the seven patients. Extubation
from a continuous positive airway pressure (CPAP) of 5 cm H2O was associated with a statistically significant rise in cardiac index from 3.44 ± 0.23 L · min-1 · m-2 to 3.73 ± 0.15L·min-1 ·m-2 related to an increase in stroke index, without significant changes in heart rate, mean arterial and pulmonary capillary
wedge pressure. Consequently the changes in myocardial oxygen consumption (8.52 ± 0.55 to 8.85 ± 0.93 ml · min-1) and coronary blood flow (172 ± 18 to 179 ± 17 ml·min-1) were less prominent than those reported during intubation, where substantial rises in myocardial oxygen consumption and
coronary flow occurred. Two patients experienced cardiac lactate production but there were no changes in systemic or coronary
haemodynamics, nor were there clinical or electrocardiographic signs of ischaemia. We conclude that extubation does not appear
to be associated with adverse systemic or coronary haemodynamic responses in patients following coronary bypass grafting.
However, the revascularized myocardium may remain vulnerable to anaerobic metabolism in the immediate postoperative period.
Pour savoir si comme ľintubation, ľextubation de la trachée provoque des perturbations hémodynamiques, on a mesuré le métabolisme
et la circulation coronarienne globale chez sept patients, au lendemain ďun pontage aorto-coronarien. On a aussi calculé les
valeurs régionales de ces mêmes variables pour cinq ďentre eux. Ľindex cardiaque de 3.44 ± 0.23 L · min-1 · m-2 sous pression positive en respiration spontanée (CPAP) de 5 cm. H2O s’est élevé à 3.73 ± 0.15 L · min-1 · m-2 post-extubation avec une augmentation significative du volume ďéjection. La fréquence cardiaque et les pressions artérielles
moyennes et capillaires pulmonaires n’ont pas changé. Ainsi ľaugmentation de la consommation ďoxygène du myocarde de 8.52
± 0.55 à 8.85 ± 0.93 ml · min-1 et celle du flot coronarien de 172 ± 18 à 179 ± 17 ml · min-1 ont été moindres que celles, importantes, déjà observées lors de ľintubation. On a noté chez deux patients une production
de lactate par le myocarde, sans changement de ľhémodynamic systémique et coronarienne non plus que de signe clinique ou électrocardiographique
ďischémie. Donc, après un pontage coronarien, ľextubation ne semble pas causer ďeffet néfaste sur les circulations systémique
et coronarienne, toutefois, le myocarde revascularisé peut demeurer sensible au métabolisme anaérobique. 相似文献
23.
Summary— To investigate if the functional alterations observed in resistance arteries of spontaneously hypertensive rats (SHRs) were also present at the coronary level, in vitro experiments were performed in mesenteric resistance arteries (MRA) and in right (RIC) and left interventricular coronary (LIC) arteries taken from 15–25-week-old SHR and age-matched Wistar Kyoto rats WKYs. Using a passive extension protocol, internal diameters corresponding to 100 mmHg intraluminal pressure (D100) were determined and vessels were set up to a normalized internal diameter (0.9 D100). SHR mesenteric resistance arteries had a significantly smaller diameter compared to WKY arteries, whereas both types of SHR coronary arteries had a greater diameter compared to those of WKY rats. In arteries in the absence of contracting agonist, nitro-L-arginine (NOLA, 100 μM) induced a progressive rise in basal tone, which could be reversed by subsequent addition of L-arginine (100 μM) but not D-arginine (100 μM). When expressed as percent of maximal contractions induced by agonists (noradrenaline, NA [10 μM] in MRA; serotonin, 5-HT [10 μM], in RIC and LIC), these contractions were significantly stronger in WKY compared to SHR coronary and mesenteric resistance arteries. In NA-precontracted MRA and 5HT-precontracted coronary arteries in the presence of indomethacin (10 μM), the magnitude of acetylcholine-induced maximal relaxations (expressed as percent of maximal contractions induced by agonists) was greater in WKY compared to SHR arteries. After a 30-min incubation period, NOLA (100 μM) completely inhibited relaxations induced by acetylcholine (0.01–10 μM) in all types of precontracted arteries. Subsequent additions of sodium nitroprusside, (SNP, 10 μM) induced complete relaxations in all preparations. These results show that a basal release of NO or NO-like compound by endothelial cells is present in isolated mesenteric resistance and coronary arteries of WKY rats and SHRs. The contribution of endothelium-derived relaxing factor-nitric oxide (EDRF-NO) to arterial tone was lower in MRA compared to coronary arteries in both strains and in SHR compared to WKY arteries. In the SHR preparations, the impaired relaxation induced by acetylcholine appeared to be due to a functional alteration of the endothelium in the presence of normal reactivity of the smooth muscle cells. 相似文献
24.
熵代表无序的水平,作者使用通气的熵变(ECV)指示肺通气的不均匀性,ECV定义为当前泡潮气量趋近于零时每摩尔被吸入气体从不均匀通气到均匀通气的熵变的极限。本文从熵的基本公式民地出ECV的计算方程。用几个数学模型肺将ECV同其他7个洗出指标进行了比较。8个指标中,只有ECV仅取决于通气分布,其他7个指标不仅取决于通气分布,还同潮气量和死腔的大小有关。这影响了它们评价肺通气不均匀性的效果,ECV的另一 相似文献
25.
松龄血脉康抑制肺动脉高压的实验研究 总被引:1,自引:0,他引:1
为观察松龄血脉康胶囊对肺动脉高压大鼠肺动脉压的影响,取100只健康Wistar大鼠,其中60只背部注射野百合碱monocrotaline,MCT80mg/kg复制出肺动脉高压模型。再将其分为两组,各30只,其中一组以标准饲料喂养,另一组加用松龄血脉康胶囊1.5g·kg-1·d-1。其余40只健康大鼠做为正常对照组,在实验当天、7天、14天、21天、28天、35天从各组中随机抽取5只行右心导管测肺动脉压。结果:注射MCT后肺高压组28天时达高峰,但加用松龄血脉康组上升幅度明显小于未用药组。结论:松龄血脉康有显著抑制大鼠肺动脉高压发展的作用 相似文献
26.
完全性肺静脉异位引流的手术治疗经验 总被引:15,自引:1,他引:14
为评估影响完全性肺静脉异位引流(TAPVD)手术纠治的因素,本组纳入了28例在中度低温体外循环和15例在深低温停循环下手术纠治者。结果手术死亡4例,死亡率9.3%。随访32例,2例肺静脉回流梗阻分别于术后5个月和2年3个月死亡。结论认为,TAPVD必须早期手术防止肺血管阻塞性病变;术后定期随访;改进手术方法,防止心房内补片粘连所致肺静脉回流梗阻。 相似文献
27.
1962~1986年25年间,经尸检病理确诊的29例新生儿肺出血,以早产儿和低出生体重儿为主,生后一周内发病者27例。本组20例有窒息史,口鼻有血性分泌物流出者17例。本文描述了新生儿肺出血的临床表现和病理特征,以及对新生儿肺出血的病因作了讨论。 相似文献
28.
Dennis J. Murphy 《Drug development research》1994,32(4):237-246
The known effects of drugs from a variety of pharmacologic/therapeutic classes on the respiratory system and worldwide regulatory requirements support the need for conducting respiratory evaluations in safety pharmacology. The objective of these studies is to evaluate the potential for drugs to cause secondary pharmacologic or toxicologic effects that influence respiratory function. Changes in respiratory function can result either from alterations in the pumping apparatus that controls the pattern of pulmonary ventilation or from changes in the mechanical properties of the lung that determine the transpulmonary pressures (work) required for lung inflation and deflation. Defects in the pumping apparatus are classified as hypo- or hyperventilation syndromes and are evaluated by examining ventilatory parameters in a conscious animal model. The ventilatory parameters include respiratory rate, tidal volume, minute volume, peak (or mean) inspiratory flow, peak (or mean) expiratory flow, and fractional inspiratory time. Defects in mechanical properties of the lung are classified as obstructive or restrictive disorders and can be evaluated in animal models by performing flow-volume and pressure-volume maneuvers, respectively. The parameters used to detect airway obstruction include peak expiratory flow, forced expiratory flow at 25 and 75% of forced vital capacity, and a timed forced expiratory volume, while the parameters used to detect lung restriction include total lung capacity, inspiratory capacity, functional residual capacity, and compliance. Measurement of dynamic lung resistance and compliance, obtained continuously during tidal breathing, is an alternative method for evaluating obstructive and restrictive disorders, respectively, and is used when the response to drug treatment is expected to be immediate (within minutes post-dose). The species used in the safety pharmacology studies conducted in our laboratory are the same as those used in toxicology studies since pharmacokinetic and toxicologic/pathologic data are available in these species. These data can be used to help select test measurement intervals and doses and to aid in the interpretation of functional change. The techniques and procedures for measuring respiratory function parameters are well established in guinea pigs, rats, and dogs. 相似文献
29.
Abstract Several methods have been used to predict successful weaning and extubation among chronic obstructive pulmonary disease (COPD) patients. The objective of this study is to determine whether carbon dioxide recruitment threshold (PCO2 RT) can be used as adjunct to conventional weaning parameters to predict early weaning and successful extubation. Twelve COPD patients who were ready to be extubated based on conventional weaning parameters were divided into group A ( n = 7) and group B ( n = 5). Group A were those patients with better weaning parameters and hence a higher probability of successful extubation as compared to group B. Carbon dioxide apnoeic threshold (PCO2 AT) was obtained by hyperventilating the patient using an increment of two breaths per min until apnoea occurs. At this point, the PCO2 AT or the PaCO2 during said apnoeic period was recorded. A dead space of 150 cc is then added to the circuit until the patient starts to breathe as evidenced by the sensitivity trigger indicator. The PCO2 obtained at this period is termed PCO2 RT. After weaning for 30 min on a T-tube, another arterial blood gas is determined and this is called the PCO2 SB or the CO2 level after 30 min on spontaneous breathing. If the PCO2 SB-PCO2 RT difference is high with a sensitivity of 85.71% and specificity of 100% vs sensitivity of 57.14% and specificity of 60% using the conventional weaning parameters. Thus an increase in PCO2 SB at 30 min T-tube is indicative of impending respiratory pump failure and that other causes of failure to wean must be investigated. 相似文献
30.
T. Urano Y. Shibayama K. Fukunishi K. Nariyama N. Ohsawa 《Virchows Archiv : an international journal of pathology》1996,427(6):607-612
We examined the effect of interruption of pulmonary arterial flow and inadequate ventilation on the development of pulmonary infarction in rats. Pulmonary arterial flow was blocked by the injection of agar into the inferior vena cava and inadequate ventilation was produced by obstructing the left main bronchus with a polypropylene tip. Histological and angiographic examination of the lung demonstrated that: pulmonary artery embolism alone does not induce pulmonary infarction; obstruction of a bronchus does not induce significant changes, but that pulmonary infarction develops when pulmonary artery embolism and obstruction of a bronchus occur simultaneously. It has been thought that pulmonary infarction is caused by acute obstruction of a pulmonary artery, however, the alveolar walls are supplied with oxygen by both the pulmonary circulation and by ventilation. Interruption of pulmonary arterial flow alone is probably not sufficient to induce pulmonary infarction, which is probably caused by deficiency of oxygen supply to the alveolar walls by a synergy between interruption of pulmonary arterial flow and inadequate ventilation. 相似文献