全文获取类型
收费全文 | 3702篇 |
免费 | 260篇 |
国内免费 | 14篇 |
专业分类
耳鼻咽喉 | 54篇 |
儿科学 | 192篇 |
妇产科学 | 48篇 |
基础医学 | 443篇 |
口腔科学 | 95篇 |
临床医学 | 328篇 |
内科学 | 683篇 |
皮肤病学 | 37篇 |
神经病学 | 273篇 |
特种医学 | 309篇 |
外科学 | 671篇 |
综合类 | 54篇 |
一般理论 | 5篇 |
预防医学 | 245篇 |
眼科学 | 67篇 |
药学 | 158篇 |
中国医学 | 1篇 |
肿瘤学 | 313篇 |
出版年
2021年 | 44篇 |
2020年 | 27篇 |
2019年 | 45篇 |
2018年 | 40篇 |
2016年 | 34篇 |
2015年 | 48篇 |
2014年 | 64篇 |
2013年 | 110篇 |
2012年 | 130篇 |
2011年 | 144篇 |
2010年 | 101篇 |
2009年 | 81篇 |
2008年 | 132篇 |
2007年 | 147篇 |
2006年 | 119篇 |
2005年 | 133篇 |
2004年 | 131篇 |
2003年 | 127篇 |
2002年 | 120篇 |
2001年 | 104篇 |
2000年 | 146篇 |
1999年 | 91篇 |
1998年 | 69篇 |
1997年 | 63篇 |
1996年 | 55篇 |
1995年 | 48篇 |
1994年 | 45篇 |
1993年 | 33篇 |
1992年 | 97篇 |
1991年 | 93篇 |
1990年 | 81篇 |
1989年 | 108篇 |
1988年 | 99篇 |
1987年 | 98篇 |
1986年 | 91篇 |
1985年 | 100篇 |
1984年 | 56篇 |
1983年 | 66篇 |
1982年 | 34篇 |
1981年 | 29篇 |
1980年 | 41篇 |
1979年 | 56篇 |
1978年 | 38篇 |
1977年 | 60篇 |
1976年 | 37篇 |
1975年 | 47篇 |
1974年 | 43篇 |
1973年 | 32篇 |
1972年 | 35篇 |
1970年 | 26篇 |
排序方式: 共有3976条查询结果,搜索用时 31 毫秒
91.
Congenital varicella in term infants: risk reconsidered 总被引:3,自引:0,他引:3
J D Meyers 《The Journal of infectious diseases》1974,129(2):215-217
92.
José T Ortiz-Pérez Sheridan N Meyers Daniel C Lee Preeti Kansal Francis J Klocke Thomas A Holly Charles J Davidson Robert O Bonow Edwin Wu 《European heart journal》2007,28(14):1750-1758
AIMS: Global angiographic scores have been developed to determine the extent of myocardium jeopardized by significant coronary stenosis. We adapted these scores to quantify the anatomic area at risk during acute myocardial infarction. We used contrast-enhanced magnetic resonance (CMR) infarct imaging to measure the portion of myocardium that developed necrosis within the so defined angiographic area at risk. METHODS AND RESULTS: In 83 subjects presenting for primary percutaneous intervention, the myocardium at risk was estimated angiographically using the Myocardial Jeopardy Index (BARI) and a modified version of the Alberta Provincial Project for Outcome Assessment in Coronary Heart Disease (APPROACH) scores. CMR was performed within a week to measure infarct size, infarct endocardial surface area (infarct-ESA), and infarct transmurality. As infarct transmurality increased, the infarct size closely approximated the myocardium at risk by angiography. In 35 subjects with transmural infarcts, the area at risk by BARI and APPROACH scores matched the infarct size (r = 0.90 and r = 0.92, P < 0.001). Additionally, BARI and APPROACH scores matched the infarct-ESA in all subjects independently of collateral flow and time to reperfusion (r = 0.90 and r = 0.87, P < 0.001). The presence of early reperfusion, collaterals, or both was associated with a progressive decrease in infarct transmurality (P < 0.001 for trend) with no difference in the infarct-ESA. CONCLUSION: The myocardium at risk of infarction can be determined angiographically as validated in subjects with transmural myocardial infarcts. Salvage provided by early reperfusion or collaterals occurs by limiting infarct transmurality, thereby the extent of endocardial infarct involved also allows estimation of the myocardium at risk in patients presenting with STEMI. 相似文献
93.
In vivo bicarbonate secretion by human esophagus. 总被引:7,自引:0,他引:7
The capacity of the human esophagus to secrete bicarbonate was studied in vivo in 10 healthy subjects. A 10-cm segment of the lower esophagus was isolated between two balloons, and the segment was perfused with an unbuffered isotonic saline solution (pH 7) for 30 minutes. The perfusate was collected, pooled, and analyzed for bicarbonate using a sensitive back-titration method. Measurements of aspirate amylase and salivary amylase and bicarbonate permitted correction of perfusate bicarbonate values for contamination by swallowed saliva. The esophagus of all 10 subjects were found to secrete bicarbonate in amounts ranging from 10 to 274 microEq/30 min (average, 78 microEq/30 min); based on in vitro studies, these amounts of bicarbonate were shown to be capable of neutralizing enough residual acid from an episode of reflux to increase pH from 2.5 almost to neutrality (pH 6-7). These findings document the presence within the human esophagus of an additional mechanism for defense against (acid) reflux damage, namely, through enhanced luminal acid clearance by the secretion of bicarbonate ions. 相似文献
94.
Mediator release after nasal airway challenge with allergen 总被引:36,自引:0,他引:36
R M Naclerio H L Meier A Kagey-Sobotka N F Adkinson D A Meyers P S Norman L M Lichtenstein 《The American review of respiratory disease》1983,128(4):597-602
An in vivo model of human allergic disease has been developed in which nasal challenge with antigen leads to physiologic changes, together with a release of increased amounts of inflammatory mediators into nasal secretions obtained by washing the nose with saline. In 105 experiments involving 35 subjects, only allergic subjects consistently demonstrated an increase in the concentrations of the mast cell mediator, histamine, and the putative mast cell mediators, TAME-esterase and PGD2. The release of each mediator was significantly (p less than 0.001) related to the physiologic change (sneezing). The release of each mediator also correlated significantly with the release of the other 2 mediators (p less than 0.001). This system, for the first time, clearly relates an in vivo symptom and mediator release and thus should provide an excellent tool for the further study of the allergic response and nasal pathophysiology. 相似文献
95.
Dina Vojinovic Hieab HH Adams Sven J van der Lee Carla A Ibrahim-Verbaas Rutger Brouwer Mirjam CGN van den Hout Edwin Oole Jeroen van Rooij Andre Uitterlinden Albert Hofman Wilfred FJ van IJcken Annemieke Aartsma-Rus GertJan B van Ommen M Arfan Ikram Cornelia M van Duijn Najaf Amin 《European journal of human genetics : EJHG》2015,23(6):837-843
The aim of our study is to investigate whether single-nucleotide dystrophin gene (DMD) variants associate with variability in cognitive functions in healthy populations. The study included 1240 participants from the Erasmus Rucphen family (ERF) study and 1464 individuals from the Rotterdam Study (RS). The participants whose exomes were sequenced and who were assessed for various cognitive traits were included in the analysis. To determine the association between DMD variants and cognitive ability, linear (mixed) modeling with adjustment for age, sex and education was used. Moreover, Sequence Kernel Association Test (SKAT) was used to test the overall association of the rare genetic variants present in the DMD with cognitive traits. Although no DMD variant surpassed the prespecified significance threshold (P<1 × 10−4), rs147546024:A>G showed strong association (β=1.786, P-value=2.56 × 10−4) with block-design test in the ERF study, while another variant rs1800273:G>A showed suggestive association (β=−0.465, P-value=0.002) with Mini-Mental State Examination test in the RS. Both variants are highly conserved, although rs147546024:A>G is an intronic variant, whereas rs1800273:G>A is a missense variant in the DMD which has a predicted damaging effect on the protein. Further gene-based analysis of DMD revealed suggestive association (P-values=0.087 and 0.074) with general cognitive ability in both cohorts. In conclusion, both single variant and gene-based analyses suggest the existence of variants in the DMD which may affect cognitive functioning in the general populations. 相似文献
96.
STUDY OBJECTIVES: To determine the effects of different levels of positive end-expiratory pressure (PEEP) during partial liquid ventilation (PLV) on gas exchange, lung compliance, and end-expiratory lung volume (EELV). DESIGN: Prospective animal study. SETTING: Animal physiology research laboratory. SUBJECTS: Nine piglets. INTERVENTIONS: Animals underwent saline solution lavage to produce lung injury. Perflubron was instilled via the endotracheal tube in a volume estimated to represent functional residual capacity. The initial PEEP setting was 4 cm H(2)O, and stepwise changes in PEEP were made. At 30-min intervals, the PEEP was increased to 8, then 12, then decreased back down to 8, then 4 cm H(2)O. MEASUREMENTS AND RESULTS: After 30 min at each level of PEEP, arterial blood gases, aortic and central venous pressures, heart rates, dynamic lung compliance, and changes in EELV were recorded. Paired t tests with Bonferroni correction were used to evaluate the data. There were no differences in heart rate or mean BP at the different PEEP levels. CO(2) elimination and oxygenation improved directly with the PEEP level and mean airway pressure (Paw). Compliance did not change with increasing PEEP, but did increase when PEEP was lowered. EELV changes correlated directly with the level of PEEP. CONCLUSIONS: As previously reported during gas ventilation, oxygenation and CO(2) elimination vary directly with PEEP and proximal Paw during PLV. EELV also varies directly with PEEP. Dynamic lung compliance, however, improved only when PEEP was lowered, suggesting an alteration in the distribution of perflubron due to changes in pressure-volume relationships. 相似文献
97.
Structured Clinical Documentation to Improve Quality and Support Practice‐Based Research in Headache
下载免费PDF全文
![点击此处可从《Headache》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Steven Meyers MD Kelly Claire Simon ScD Stuart Bergman‐Bock MD Franco Campanella DO Revital Marcus MD Angela Mark MD Thomas Freedom MD Susan Rubin MD Irene Semenov DO Rebekah Lai BS Laura Hillman BBA Samuel Tideman MS Anna Pham BS Roberta Frigerio MD Demetrius M. Maraganore MD 《Headache》2018,58(8):1211-1218
98.
Monica Sethi Clark G. Owyang Chad Meyers Ram Parekh Kaushal H. Shah Alex F. Manini 《The American journal of emergency medicine》2018,36(4):625-629
Objective
Balanced resuscitative fluids (BF) have been associated with decreased incidence of hyperchloremic metabolic acidosis in sepsis. We hypothesized that higher proportions of BF during resuscitation would thus be associated with improved mortality in Emergency Department (ED) patients with sepsis.Methods
This was a retrospective chart review of adult ED patients who presented with sepsis to a large, urban teaching hospital over one year. The choice of resuscitation fluid in the first 2 days of hospitalization was defined as either normal saline (NS) or balanced fluids (BF; Lactated Ringer's or Isolyte). The primary study outcome was in-hospital mortality, which was analyzed with multivariable logistic regression based on the proportion of BF received during the initial ED resuscitation.Results
Of 149 patients screened, 33 were excluded, leaving 115 for analysis, of whom 18 died (16% overall mortality). Sixty-one (53%) patients received BF and NS, 6 (5%) patients received BF exclusively, while 48 (42%) patients received NS only. The mean number of liters administered was 5.4, and the mean percentage of BF administered was 29%. In univariate analysis, a higher proportion of BF was associated with lower odds of mortality (OR 0.973 [95% CI 0.961–0.986], p = 0.00003). This association held true in multivariable models controlling for comorbidities and admission lactate level.Conclusions
We found that the proportion of BF during the initial ED resuscitation in septic patients was associated with a significant reduction in mortality. This association provides the necessary rationale for future randomized clinical trials of BF resuscitation in sepsis. 相似文献99.
Patricia J. Coon Eugene R. Bleecker Donald T. Drinkwater Deborah A. Meyers Andrew P. Goldberg 《Metabolism: clinical and experimental》1989,38(12):1201-1209
The relationships of age, body composition, and physical conditioning status to glucose tolerance, insulin, and lipoprotein levels were examined in 77 healthy, nonsmoking white male volunteers, aged 46 to 73 years with no evidence of coronary artery or endocrine-metabolic disease. The men had a wide range of body fat (13% to 39%), indexed as waist-to-hip ratio (WHR, 0.84 to 1.08), and maximal aerobic capacity (VO2max, 17 to 48 mL/kg.min). Multiple regression analysis with age, VO2max, WHR, and percent body fat as independent variables demonstrated that fasting plasma insulin, triglyceride (TG), and high density lipoprotein cholesterol (HDL-C) levels were independently related to both percent body fat and WHR. In contrast, fasting plasma glucose levels and insulin responses during oral glucose tolerance tests (OGTT) correlated independently with percent body fat, and glucose responses to OGTT correlated only with WHR. Although fasting plasma TG and HDL-C correlated with glucose and insulin levels, in multiple regression analyses only percent body fat and WHR were the significant independent variables. Fasting total and low density lipoprotein cholesterol values were not related to these variables. To test the effects of weight loss and exercise training on these relationships, 20 obese men of comparable age, percent body fat, WHR, and VO2max were randomly assigned to weight loss or aerobic exercise training programs. A 12% +/- 3% loss in body weight (P less than .01, mean +/- SD) resulted in a 19% +/- 9% decline in body fat (P less than .01) with no change in fat free mass, WHR, or VO2max.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
100.
Viola M. Young William F. Meyers Marcia R. Moody Stephen C. Schimpff 《The American journal of medicine》1981,70(3):646-650
Corynebacterium species that are normally abundant on the skin and mucous membranes rarely cause infections and are susceptible to most antibiotics. The report in 1976 of four cases of sepsis at the National Institutes of Health caused by a hitherto undescribed Corynebacterium that is highly antibiotic resistant, but uniformly susceptible to vancomycin, alerted the medically oriented scientific community to the emergence of these organisms as a possible new cause of nosocomial infections. Although we have always performed antibiotic susceptibility tests on all microorganisms recovered from normally sterile body fluids, our first recovery of these organisms was in August 1977. Since then we have recovered 52 such strains from 39 patients, most frequently from the rectum, followed by the groin, blood, lesions and urine in order of predominance. Characterization by API 50 L strips revealed that most, but not all strains resemble the JK group of Riley et al. [1]. Cell wall studies and DNA base ratios further confirmed their status as corynebacteria. Hospital acquisition has been proved; cross infection between patients is the most likely mode of spread. Their recognition is necessary for optimal preventive and therapeutic care of patients with compromised host defenses. 相似文献