全文获取类型
收费全文 | 2577篇 |
免费 | 136篇 |
国内免费 | 8篇 |
专业分类
耳鼻咽喉 | 56篇 |
儿科学 | 110篇 |
妇产科学 | 51篇 |
基础医学 | 227篇 |
口腔科学 | 55篇 |
临床医学 | 250篇 |
内科学 | 500篇 |
皮肤病学 | 23篇 |
神经病学 | 204篇 |
特种医学 | 69篇 |
外国民族医学 | 7篇 |
外科学 | 533篇 |
综合类 | 37篇 |
一般理论 | 2篇 |
预防医学 | 179篇 |
眼科学 | 54篇 |
药学 | 188篇 |
中国医学 | 2篇 |
肿瘤学 | 174篇 |
出版年
2023年 | 21篇 |
2022年 | 42篇 |
2021年 | 81篇 |
2020年 | 58篇 |
2019年 | 71篇 |
2018年 | 90篇 |
2017年 | 74篇 |
2016年 | 69篇 |
2015年 | 65篇 |
2014年 | 100篇 |
2013年 | 125篇 |
2012年 | 232篇 |
2011年 | 222篇 |
2010年 | 110篇 |
2009年 | 87篇 |
2008年 | 162篇 |
2007年 | 172篇 |
2006年 | 148篇 |
2005年 | 121篇 |
2004年 | 135篇 |
2003年 | 96篇 |
2002年 | 99篇 |
2001年 | 36篇 |
2000年 | 25篇 |
1999年 | 27篇 |
1998年 | 16篇 |
1997年 | 4篇 |
1996年 | 21篇 |
1995年 | 13篇 |
1994年 | 7篇 |
1993年 | 6篇 |
1992年 | 23篇 |
1991年 | 19篇 |
1990年 | 12篇 |
1989年 | 12篇 |
1988年 | 20篇 |
1987年 | 14篇 |
1986年 | 9篇 |
1985年 | 7篇 |
1984年 | 6篇 |
1983年 | 6篇 |
1982年 | 6篇 |
1981年 | 5篇 |
1979年 | 9篇 |
1977年 | 3篇 |
1975年 | 8篇 |
1972年 | 3篇 |
1971年 | 3篇 |
1968年 | 4篇 |
1965年 | 3篇 |
排序方式: 共有2721条查询结果,搜索用时 15 毫秒
11.
Plotkowski MC Costa AO Morandi V Barbosa HS Nader HB de Bentzmann S Puchelle E 《Journal of medical microbiology》2001,50(2):183-190
Tight junctions seal polarised surface epithelial respiratory cells so as to prevent the passage of bacteria and toxins through the epithelial sheet. Disruption of tight junctions, which may occur during injury and repair processes of airway epithelium, favours potential bacterial interaction with receptors from cell basolateral membranes. Earlier studies reported that non-polarised and untight epithelial respiratory cells are highly susceptible to Pseudomonas aeruginosa adherence and internalisation. As heparan sulphate proteoglycans (HSP) from cell basolateral membranes in epithelial cells without tight junctions may become accessible to bacterial ligands, the present study investigated their role as potential receptors for non-piliate P. aeruginosa ligands. Treatment of cells with heparitinase I and II significantly reduced (51.2% and 51.7%, respectively) P. aeruginosa adherence to epithelial respiratory cells without tight junctions. The internalisation of bacteria was not affected by treatment with heparitinases. Treatment of the bacteria with heparin and heparan sulphate also significantly reduced their adherence to respiratory cells (34.3% and 43.7%, respectively). Treatment of cells with other enzymes (trypsin, lipase and chondroitinase ABC) or treatment of bacteria with chondroitin-4-sulphate did not modify the adherence to respiratory cells significantly. Both affinity chromatography and Western blotting assays showed the interaction of different P. aeruginosa outer-membrane proteins (OMPs) with heparin. Several bacterial strains showed differences in their profile of heparin-binding OMPs, but all exhibited low mol. wt (< 30 kDa) reactive proteins. Reactivity of whole bacterial cells with heparin was also observed by transmission electron microscopy. These results suggest that HSP are potential receptors for P. aeruginosa adherence to non-polarised and untight epithelial respiratory cells. 相似文献
12.
Rainer Burghard Ralf Pallacks Nader Gordjani Jekabs U. Leititis Bernhard J. Hackelöer Matthias Brandis 《Pediatric nephrology (Berlin, Germany)》1987,1(4):574-580
Protein content and protein composition were studied in amniotic fluid obtained from 171 healthy pregnant women between the 16th and 38th week of gestation, using microgradient gel electrophoresis to separate proteins according to their molecular size into albumin (68 KD), proteins of low molecular weight (LMW proteins, <68 KD), and proteins of high molecular weight (HMW proteins, >68 KD). Additionally -1-microglobulin (-1-MG, 33 KD) and -2-microglobulin (-2-MG, 11,8 KD) were analysed as micromolecular marker proteins. Concentrations of LMW proteins were 0.15–0.22 g/l, of -1-MG 28.4–34.5 mg/l, and of -2-MG 7.2–11.6 mg/l during the second trimester of gestation, and thereafter decreased progressively to 0.03 g/l, 14.1 mg/l and 2.4 mg/l respectively near term. The same developmental trends were confirmed by calculating the protein/creatinine ratios in amniotic fluid. The concentrations of LMW proteins found in the first postnatal urine of 73 healthy infants born prematurely or at term were similar to those in amniotic fluid of corresponding fetal age. Concentrations of albumin and HMW proteins in postnatal urine were about 5% and 15% respectively when compared with amniotic fluid concentrations. No strong correlation existed between gestational age and either of the analysed proteins which would allow accurate assessment of fetal maturation by protein analysis in amniotic fluid. It is concluded that fetal urinary excretion is the major determinant of the microprotein content of amniotic fluid. Microproteins seem to reflect an increasing tubular reabsorption capacity, which accelerates rapidly after the second trimester of gestation. 相似文献
13.
Polyorchidism is usually diagnosed incidentally when the patient undergoes imaging or surgery for some other reason. Although we are facing lack of evidence in different steps of diagnostic and therapeutic workup of these patients, this disorder is usually considered benign, not requiring any intervention. We report the case of a man complaining of a palpable mass in his scrotum. We evaluated the patient using ultrasound, MRI and serum tumour marker level measurement. The patient was finally diagnosed with polyorchidism (three testes). For the management, we recommended annual physical examination, US examination and serum tumour marker level measurement. 相似文献
14.
15.
Dimitrios Moris Brian I. Shaw Cecilia Ong Ashton Connor Mariya L. Samoylova Samuel J. Kesseli Nader Abraham Jared Gloria Robin Schmitz Zachary W. Fitch Bryan M. Clary Andrew S. Barbas 《肝胆外科与营养》2021,10(3):315
BackgroundSelection of the optimal treatment modality for primary liver cancers remains complex, balancing patient condition, liver function, and extent of disease. In individuals with preserved liver function, liver resection remains the primary approach for treatment with curative intent but may be associated with significant mortality. The purpose of this study was to establish a simple scoring system based on Model for End-stage Liver Disease (MELD) and extent of resection to guide risk assessment for liver resections.MethodsThe 2005–2015 NSQIP database was queried for patients undergoing liver resection for primary liver malignancy. We first developed a model that incorporated the extent of resection (1 point for major hepatectomy) and a MELD-Na score category of low (MELD-Na =6, 1 point), medium (MELD-Na =7–10, 2 points) or high (MELD-Na >10, 3 points) with a score range of 1–4, called the Hepatic Resection Risk Score (HeRS). We tested the predictive value of this model on the dataset using logistic regression. We next developed an optimal multivariable model using backwards sequential selection of variables under logistic regression. We performed K-fold cross validation on both models. Receiver operating characteristics were plotted and the optimal sensitivity and specificity for each model were calculated to obtain positive and negative predictive values.ResultsA total of 4,510 patients were included. HeRS was associated with increased odds of 30-day mortality [HeRS =2: OR =3.23 (1.16–8.99), P=0.025; HeRS =3: OR =6.54 (2.39–17.90), P<0.001; HeRS =4: OR =13.69 (4.90–38.22), P<0.001]. The AUC for this model was 0.66. The AUC for the optimal multivariable model was higher at 0.76. Under K-fold cross validation, the positive predictive value (PPV) and negative predictive value (NPV) of these two models were similar at PPV =6.4% and NPV =97.7% for the HeRS only model and PPV =8.4% and NPV =98.1% for the optimal multivariable model.ConclusionsThe HeRS offers a simple heuristic for estimating 30-day mortality after resection of primary liver malignancy. More complicated models offer better performance but at the expense of being more difficult to integrate into clinical practice. 相似文献
16.
The purpose of the present study was to examine whether a history of responding under schedules that generate either high or low response rates could modify previously established cocaine self-administration. Eight experimentally naive rhesus monkeys were trained to respond on one of two levers under a fixed-interval (FI) 5-min schedule of intravenous cocaine (0.03 mg/kg per injection) presentation. When responding was stable a cocaine dose-response curve (saline, 0.01–0.3 mg/kg per injection) was determined. Following completion of the dose-response curves, the monkeys were randomly assigned to one of two groups (n=4/group) and trained to respond on the other lever under either a fixed-ratio (FR) 50 or inter-response times (IRT) > 30-s schedule of cocaine (0.03 mg/kg per injection) presentation. After 65 sessions responding was again maintained under the FI5-min schedule of 0.03 mg/kg per injection cocaine for 60 sessions, followed by redetermination of the cocaine dose-response curve. During the initial exposure to the FI schedule, the mean rate of responding was 4.02 (± 0.33) responses/min and the cocaine dose-response curve was characterized as an inverted-U shape function of dose, with peak responding at 0.03 mg/kg per injection. The FR50 schedule generated high rates (66.80 ± 5.6 responses/min), while response rates under the IRT > 30-s schedule were low (2.62 ± 0.2 responses/min). Following different behavioral histories, response rates under the FI5-min schedule were significantly higher for 60 sessions in FR-history monkeys compared to IRT-history subjects. Compared to the initial FI baselines, cocaine intake (mg/kg per session) was significantly higher following an FR-history and significantly lower following training under an IRT schedule, for 60 consecutive sessions. In addition, there was a significant effect of behavioral history on the cocaine dose-response curve, such that descending limb was shifted farther to the right in FR-history subjects compared to IRT-history monkeys. Results from the present study indicate that previously established drug-seeking behavior can be modified by training under different reinforcement schedules. Knowledge of such historical variables may be important in understanding the determinants of drug self-administration. 相似文献
17.
Nader Gordjani Rainer Burghard Dirk Müller Helga Mathäi Gunther Mergehenn Jekabs U. Leititis Matthias Brandis 《Pediatric nephrology (Berlin, Germany)》1995,9(4):419-422
The potential tubulotoxicity of tobramycin and cefotaxim were assessed in neonates by measuring the urinary level of adenosine deaminase binding protein (ABP) and urinary 1-microglobulin and 2-microglobulin. In a prospective study, 33 neonates who received tobramycin and cefotaxim for suspected neonatal sepsis were compared with 48 untreated newborns during the first 10 days of life. The urinary concentrations of ABP and its excretion rates, corrected for body weight and body surface area, were significantly increased from the 1st day of treatment. Urinary 1-microglobulin and 2-microglobulin were not elevated under tobramycin and cefotaxim during the first 2 days of treatment. We conclude that ABP may be a sensitive marker for the detection of proximal renal tubular injury during tobramycin and cefotaxim treatments of neonates. The increase in urinary ABP which occurs before an elevation of urinary 1-microglobulin and 2-microglobulin may reflect earlier structural than functional alterations. However, since none of the treated infants had signs of electrolyte disorders or glomerular dysfunction, the clinical relevance of ABP measurement should be reevaluated. 相似文献
18.
Nader N. Boushra 《Journal canadien d'anesthésie》1996,43(6):599-616
Purpose
Sleep apnoea syndrome (SAS) is a relatively common, potentially fatal, disorder. Patients with SAS exhibit repetitive, often prolonged episodes of apnoea during sleep, with serious nocturnal and diurnal physiologic derangements. Several anecdotal reports and clinical studies have documented anaesthetic-related occurrence of fatal and near-fatal respiratory complications in these patients. The purpose of this article is to outline the potential problems encountered in anaesthetic management of adult SAS patients, and to suggest a practical approach for anaesthesia both for incidental and specific procedures.Principal findings
SASs have many implications for the anaesthetist. First, SAS patients are exquisitely sensitive to all central depressant drugs, with upper airway obstruction or respiratory arrest occurring even with minimal doses. Thus sedative and opioid premedication should be omitted as should the intra and postoperative use of opioids be limited or avoided. All anaesthetic drugs should be administered by titration to desired effect, preferably using short-acting drugs. When feasible, continuous regional anaesthesia using a catheter is the technique of choice. Where possible nonopioid analgesics or local anaesthetics should be used for postoperative analgesia. Perioperative monitoring for apnoea, desaturation, and dysrhythmias is essential. Secondly, SAS patients have a potentially difficult airway. Awake intubation is the safest approach to airway control. Extubation should only be tried in the fully conscious patient with intact upper airway function and under controlled situations. Thirdly, the cardiorespiratory complications of SAS and the presence of associated diseases can adversely influence anaesthetic management.Conclusion
Perioperative risks attending SAS patients emphasize the importance of their detection, perioperative evaluation and planning. 相似文献19.
The development of scales to measure knowledge and preference for diet and physical activity behavior in 4- to 8-year-old children 总被引:2,自引:0,他引:2
K J Calfas J F Sallis P R Nader 《Journal of developmental and behavioral pediatrics : JDBP》1991,12(3):185-190
Although there is a sizable literature on determinants of health-related habits in adults, relatively little attention has been paid to influences on health habits in children. The purpose of this study was to (a) develop practical, reliable, and valid measures of knowledge of and preference for cardiovascular disease-related diet and exercise behaviors in children, and (b) assess parental influences on children's knowledge and preference. Eighty-one 4- to 8-year-old children from diverse ethnic backgrounds and their parent or legal guardian participated. Children were presented with 15 attractive photo-pairs of foods. One photograph was of a "healthful" food or activity, and the other was "unhealthful." They were asked to identify which food/activity of the pair they preferred, and which one they thought was more healthy. Children were retested after 1 week to determine test-retest reliability. Validity of the preference tests was determined by giving the child actual choices of the same activity and food pairs. Validity of knowledge tests was determined by testing children after an educational intervention session. The alpha coefficients, test-retest reliabilities, and validity data generally indicated that food preference and knowledge tests had adequate psychometric properties, but the physical activity scales did not. Very few parental influences on health-related behavior were detected. 相似文献
20.
Michal Laniado-Schwartzman Nader G. Abraham 《Pediatric nephrology (Berlin, Germany)》1992,6(5):490-498
In addition to cyclooxygenase and lipoxygenase, arachidonic acid (AA) is metabolized by the cytochrome P-450 monooxygenase system. The kidney is one of the major extrahepatic tissues that display cytochrome P-450 enzyme activities, in particular the cortex, specifically the proximal tubule demonstrate the highest concentration. AA is metabolized by the renal cytochrome P-450 epoxygenase and /-1 hydroxylases to epoxyeicosatrienoic acids and /-1 alcohols (20- and 19-mono-hydroxyeicosatetraenoic acids), respectively. These metabolites possess a broad spectrum of biological and renal effects which include: vasodilation, vasoconstriction, inhibition and stimulation of Na+–K+-ATPase, inhibition of ion transport mechanisms, natriuresis, inhibition of renin release and stimulation of cell growth. These metabolites are endogenous constituents of the kidney and are present in urine with increasing concentration under pathological conditions such as pregnancy-induced hypertension. The cytochrome P-450-dependent metabolism of AA is specifically localized to the proximal tubule and exhibits developmental changes, i.e., renal production of metabolites is very low in the fetus, newborn and up to 3 weeks of age, after which a remarkable increase in enzyme activities is observed. These characteristics call attention to the importance of this enzyme system in producing cellular mediators for regulating renal function in normal and diseased states. 相似文献