全文获取类型
收费全文 | 18339篇 |
免费 | 1471篇 |
国内免费 | 44篇 |
专业分类
耳鼻咽喉 | 194篇 |
儿科学 | 594篇 |
妇产科学 | 370篇 |
基础医学 | 2850篇 |
口腔科学 | 427篇 |
临床医学 | 1871篇 |
内科学 | 4001篇 |
皮肤病学 | 302篇 |
神经病学 | 1592篇 |
特种医学 | 521篇 |
外国民族医学 | 2篇 |
外科学 | 2372篇 |
综合类 | 133篇 |
一般理论 | 9篇 |
预防医学 | 1520篇 |
眼科学 | 365篇 |
药学 | 1413篇 |
中国医学 | 20篇 |
肿瘤学 | 1298篇 |
出版年
2023年 | 124篇 |
2022年 | 217篇 |
2021年 | 385篇 |
2020年 | 288篇 |
2019年 | 373篇 |
2018年 | 410篇 |
2017年 | 359篇 |
2016年 | 423篇 |
2015年 | 395篇 |
2014年 | 583篇 |
2013年 | 725篇 |
2012年 | 1022篇 |
2011年 | 983篇 |
2010年 | 546篇 |
2009年 | 545篇 |
2008年 | 794篇 |
2007年 | 853篇 |
2006年 | 796篇 |
2005年 | 716篇 |
2004年 | 797篇 |
2003年 | 690篇 |
2002年 | 654篇 |
2001年 | 445篇 |
2000年 | 489篇 |
1999年 | 434篇 |
1998年 | 208篇 |
1997年 | 168篇 |
1996年 | 178篇 |
1995年 | 159篇 |
1994年 | 157篇 |
1993年 | 151篇 |
1992年 | 316篇 |
1991年 | 345篇 |
1990年 | 338篇 |
1989年 | 347篇 |
1988年 | 274篇 |
1987年 | 291篇 |
1986年 | 246篇 |
1985年 | 303篇 |
1984年 | 204篇 |
1983年 | 172篇 |
1982年 | 134篇 |
1981年 | 112篇 |
1980年 | 94篇 |
1979年 | 174篇 |
1978年 | 127篇 |
1977年 | 115篇 |
1975年 | 102篇 |
1974年 | 127篇 |
1973年 | 109篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
11.
12.
Nutrition labels in bar graph format deemed most useful for consumer purchase decisions using adaptive conjoint analysis 总被引:1,自引:1,他引:0
C J Geiger B W Wyse C R Parent R G Hansen 《Journal of the American Dietetic Association》1991,91(7):800-807
This study estimated the effects of changing multiple levels and combinations of nutrition information format, load, expression, and order on consumers' perceptions of label usefulness in purchase decisions using adaptive conjoint analysis. A shopping mall intercept survey, which was administered by a marketing research firm, assessed consumer preferences for 12 label alternatives produced on Campbell's soup cans to portray nutrition information realistically; 252 of 258 respondents completed the computer interactive interview. Consumers significantly preferred the bar graph format to the bar graph/nutrient density and traditional label formats. Consumers considered the bar graph/nutrient density format to be as useful as the traditional label format. There was a highly significant difference among the three levels of information load; the most information load was preferred regardless of nutrient importance. Consumers significantly preferred nutrition information stated in absolute numbers and percentages vs in absolute numbers only in traditional, or in percentages only expressions. There was a significant difference between consumer preferences for the two types of information order. The findings indicate that consumers clearly preferred the nutrition label that displayed all nutrient values using a bar graph format, offered the most information load, and expressed nutrient values using both absolute numbers and percentages. Consumers also preferred nutrition information rearranged in an order that grouped nutrients that should be consumed in adequate amounts on the top, calories in the middle, and nutrients that should be consumed in lesser amounts on the bottom of the label. 相似文献
13.
Antigenic evidence for simultaneous expression of two different lipooligosaccharides by some strains of Haemophilus influenzae type b. 总被引:8,自引:5,他引:3
下载免费PDF全文
![点击此处可从《Infection and immunity》网站下载免费的PDF全文](/ch/ext_images/free.gif)
C C Patrick S E Pelzel E E Miller E Haanes-Fritz J D Radolf P A Gulig G H McCracken Jr E J Hansen 《Infection and immunity》1989,57(7):1971-1978
Isolates of Haemophilus influenzae type b (Hib) can be divided into three antigenic groups based on their reactivities with a set of two monoclonal antibodies (MAbs) directed against epitopes in the oligosaccharide region of Hib lipooligosaccharide (LOS) (P. A. Gulig, C. C. Patrick, L. Hermanstorfer, G. H. McCracken, Jr., and E. J. Hansen, Infect. Immun. 55:513-520, 1987). Approximately 24% of Hib strains react with both of these LOS-specific MAbs. Immunoprecipitation experiments involving several of these strains indicated that the epitopes recognized by these MAbs resided in two different LOS molecules, both of which were synthesized by these particular Hib strains. In addition, Western blot (immunoblot) analysis of proteinase K-treated cell extracts of these strains that had been subjected to sodium dodecyl sulfate-polyacrylamide gradient gel electrophoresis revealed two different LOS staining patterns when they were probed independently with the two MAbs. Colony blot radioimmunoassay of hundreds of colonies of one of these Hib strains showed that each colony bound both MAbs. Immune electron microscopy confirmed that individual cells of this same Hib strain expressed both types of LOS molecule at the same time. An antibody accessibility radioimmunoassay was used to show that different Hib strains of this type varied in the relative amounts of each of the two MAbs that they could bind to their cell surfaces. These findings indicate that some Hib strains can synthesize two antigenically distinct LOS molecules simultaneously. 相似文献
14.
15.
R Hansen G A MacKinlay W G Manson 《Archives of disease in childhood》2006,91(6):541-2; author reply 542
16.
The Monk Duopleet femoral interlocking uncemented two-component endoprosthesis consists of a polyethylene cup covered by a metal cap and an Austin-Moore type stem. Seventy-two patients (average age, 71 years) were treated by this arthroplasty: 27 for subcapital femoral neck fracture, 36 for osteoarthritis, and nine as an exchange operation. Three patients died following operation. After a mean follow-up time of 50 months, 47 patients were reexamined clinically and radiographically. Because of loosening, four patients had the prosthesis removed. Twenty-six patients were classified as excellent, 12 as good, six as fair, and three as poor. There were no cases of acetabular intrusion. The Monk Duopleet prosthesis may solve the problem of the loosening that had been associated with femoral component alone. The long-term results are promising and appear to be better than the results of the standard Moore prosthesis. The Monk Duopleet prosthesis is an alternative to other two-component endoprostheses for the treatment of subcapital hip fractures and in the group of patients suffering from osteoarthritis, where an arthroplasty with a cemented prosthesis may be considered hazardous because of age or general disease. 相似文献
17.
Diana H. Yu BA ; Kimberly A. Mace PhD ; Scott L. Hansen MD ; Nancy Boudreau PhD ; David M. Young MD 《Wound repair and regeneration》2007,15(5):628-635
Insulin-like growth factor-1 (Igf-1), a critical mediator of tissue repair, is significantly decreased in diabetic wounds. Furthermore, decreased levels of hypoxia-inducible factor 1-alpha (Hif-1alpha) and its target genes are also associated with impaired wound healing in diabetic mice. The aim of our study was to examine whether the reduced levels of Igf-1 are responsible for the reduction in Hif-1alpha protein synthesis and activity in diabetic wounds. We provide evidence that Igf-1 regulates Hif-1alpha protein synthesis and activity during wound repair. In addition, Igf-1 stimulated phosphytidylinositol 3-kinase activity in diabetic fibroblasts, which, in turn, increased activation of the translational regulatory protein, p70 S6 kinase. Moreover, improved healing of diabetic wounds by addition of recombinant IGF-1 protein was associated with an increase in Hif-1alpha protein synthesis and function in vivo. 相似文献
18.
19.
Anne?Helene?Garde ?se?Marie?Hansen Johnni?Hansen 《International archives of occupational and environmental health》2009,82(10):1219-1228
Background
Sleep problems are common effects of shift work. The aim of the present study was to evaluate how different types of shift affect sleep and sleepiness, and to relate sleepiness to urinary 6-sulfatoxymelatonin. 相似文献20.
OBJECTIVE: Based on recent safety and efficacy data, combined with the known pharmacokinetic parameters of aminoglycosides in the newborn, once-daily gentamicin should be preferable to the many other dosing regimens currently in use. Although there are growing data to support its use in term newborns, experience with preterm infants is more limited. In our Neonatal Intensive Care Unit, we experienced difficulties regarding complicated dosing regimens, actual dosing errors, and the tendency to check trough and peak levels around the third dose for infants receiving only a 48 hour course. Therefore, we conducted a quality improvement initiative in which we developed and tested a clinical practice guideline for the use of once-daily gentamicin for preterm and term infants that we hoped would yield trough and peak levels in our target range. METHODS: We combined a review of the published English language literature with pharmacokinetic analysis of our own data prior to initiation of this new regimen to design the following dosing regimen: <35 weeks gestation: 3 mg/kg q 24 hours, > or =35 weeks gestation: 4 mg/kg q 24 hours. Our goal serum levels were a trough < or =2 microg/ml and a peak between 6 and 12 microg/ml. We collected and analyzed trough and peak levels from all infants receiving this dosing regimen in the first week of life for at least 72 hours between 3/1/99 and 12/31/00. RESULTS: In total, 214 babies met our inclusion criteria, 75 of whom were <35 weeks gestation. 100% of babies of all gestational ages had a nontoxic trough level. For infants <35 weeks gestation, 79% had a therapeutic peak level, with a mean value of 6.8 microg/ml. For infants of at least 35 weeks gestation, 93% had a therapeutic peak level, with a mean value of 8.4 microg/ml. 92% of nontherapeutic peaks were too low. CONCLUSION: This study of once-daily gentamicin represents the largest sample size of pre-term infants published to date. The proposed regimen is simple and yields a high proportion of desirable levels. We recommend it for use in preterm and term newborns. 相似文献