全文获取类型
收费全文 | 99625篇 |
免费 | 7083篇 |
国内免费 | 321篇 |
专业分类
耳鼻咽喉 | 1274篇 |
儿科学 | 2534篇 |
妇产科学 | 2306篇 |
基础医学 | 12437篇 |
口腔科学 | 2061篇 |
临床医学 | 9740篇 |
内科学 | 21742篇 |
皮肤病学 | 1065篇 |
神经病学 | 8652篇 |
特种医学 | 3357篇 |
外国民族医学 | 3篇 |
外科学 | 16223篇 |
综合类 | 1401篇 |
现状与发展 | 1篇 |
一般理论 | 75篇 |
预防医学 | 7883篇 |
眼科学 | 2649篇 |
药学 | 6340篇 |
中国医学 | 142篇 |
肿瘤学 | 7144篇 |
出版年
2023年 | 401篇 |
2022年 | 692篇 |
2021年 | 1646篇 |
2020年 | 880篇 |
2019年 | 1586篇 |
2018年 | 1903篇 |
2017年 | 1399篇 |
2016年 | 1552篇 |
2015年 | 1834篇 |
2014年 | 2726篇 |
2013年 | 4318篇 |
2012年 | 6185篇 |
2011年 | 6454篇 |
2010年 | 3618篇 |
2009年 | 3343篇 |
2008年 | 6123篇 |
2007年 | 6815篇 |
2006年 | 6512篇 |
2005年 | 6661篇 |
2004年 | 6495篇 |
2003年 | 6113篇 |
2002年 | 6103篇 |
2001年 | 782篇 |
2000年 | 538篇 |
1999年 | 764篇 |
1998年 | 1281篇 |
1997年 | 1137篇 |
1996年 | 960篇 |
1995年 | 964篇 |
1994年 | 844篇 |
1993年 | 741篇 |
1992年 | 562篇 |
1991年 | 510篇 |
1990年 | 445篇 |
1989年 | 461篇 |
1988年 | 433篇 |
1987年 | 449篇 |
1986年 | 443篇 |
1985年 | 496篇 |
1984年 | 706篇 |
1983年 | 754篇 |
1982年 | 977篇 |
1981年 | 915篇 |
1980年 | 866篇 |
1979年 | 447篇 |
1978年 | 529篇 |
1977年 | 579篇 |
1976年 | 490篇 |
1975年 | 428篇 |
1974年 | 339篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
32.
Jennifer Tuboku-Metzger Blakely Ronda L Sinkowitz-Cochran William R Jarvis 《Infection control and hospital epidemiology》2006,27(8):873-875
A 19-item survey instrument was designed and mailed by the Infectious Diseases Society of America to its membership to determine the media preferred by infectious diseases physicians for continuing medical education on general topics and on antimicrobial resistance. The objective of the survey was to offer the developers of educational programs knowledge on which to base more-effective ways to deliver educational materials to physicians in this specialty. 相似文献
33.
Maren T Scheuner William C Whitworth Henraya McGruder Paula W Yoon Muin J Khoury 《Genetics in medicine》2006,8(8):525-531
PURPOSE: We examined the performance of a familial risk assessment method that stratifies risk for early-onset coronary heart disease by considering the number of relatives with coronary disease, degree of relationship, lineage, and age at diagnosis. METHODS: By using data from the HealthStyles 2003 survey, we assessed the associations between familial risk and early-onset coronary heart disease, diabetes, hypercholesterolemia, hypertension, and obesity. By using area under the curve statistics, we evaluated the discriminatory ability of various risk assessment models. RESULTS: Of 4,035 respondents, 60% were female and 72% were white, with a mean age of 48.8 years. After adjustment for demographics, strong and moderate risk were significantly associated with approximately a five- and twofold risk of early-onset coronary disease, respectively. After adjustment for demographics and personal history of cardiovascular disease, strong familial risk was also significantly associated with diabetes, hypercholesterolemia, hypertension, and obesity. A risk assessment model that included familial risk, demographics, and personal history of diabetes, hypercholesterolemia, hypertension, and obesity was most optimal with an area under the curve statistic of 87.2% CONCLUSIONS: Familial risk assessment can stratify risk for early-onset coronary heart disease. Several conditions associated with increased familial risk can be prevented. These results have important implications for risk assessment and risk-reducing interventions. 相似文献
34.
Cardiovascular calcification in end-stage renal disease. 总被引:13,自引:1,他引:12
Cardiovascular diseases are common in patients with end-stage renal disease (ESRD) and cardiovascular morbidity and mortality among dialysis patients are substantially higher than in the general population. The reasons for this high incidence are multiple. They include traditional factors such as hypertension, diabetes, dyslipidaemia, sodium overload, and elevated homocysteine levels as well as disturbances of mineral metabolism, specifically abnormalities in phosphorus and calcium homeostasis. This review will describe the specific cardiovascular complications related to calcifications in ESRD, the implications of the abnormalities of mineral metabolism in its pathogenesis and the current imaging techniques available for the detection of cardiovascular calcifications. Excess of calcium load contributes to the development of cardiac calcifications; therefore, alternative strategies to diminish exogenous calcium load should be considered in patients with ESRD. 相似文献
35.
Predictors of clustering of tuberculosis in Greater Vancouver: a molecular epidemiologic study 总被引:3,自引:0,他引:3
下载免费PDF全文
![点击此处可从《Canadian Medical Association journal》网站下载免费的PDF全文](/ch/ext_images/free.gif)
36.
William A. Kennedy II Ralph Buttyan Eduardo Garcia-Montes Carl A. Olsson Ihor S. Sawczuk 《Urology》1997,49(6):973-980
Objectives. Acute unilateral ureteral obstruction (UUO) results in ipsilateral hydronephrosis characterized by a decrease in epidermal growth factor (EGF) mRNA expression and EGF protein levels in the distal renal tubules. UUO results in programmed cell death with increases in the characteristic markers of apoptosis. To suppress the apoptotic response during UUO, recombinant EGF was administered during renal obstruction and the ensuing molecular and histologic changes were studied.Methods. Mature Sprague-Dawley rats underwent left ureteral obstruction and the kidneys were harvested at 24, 48, and 72 hours. Markers of apoptosis included DNA laddering pattern on agarose gel electrophoresis, in situ gap labeling of fragmented DNA for quantitative apoptotic body determination, polyadenylated mRNA expression of SGP-2, and in situ hybridization for sulfated glycoprotein-2 (SGP-2) mRNA. Studies were repeated in rats following administration of 10, 20, and 40 μg of subcutaneous recombinant EGF on a daily basis after UUO.Results. Subcutaneous injection of EGF into unilaterally obstructed rats promotes renal tubular epithelial cell regeneration, as demonstrated by increased cortical mitotic activity. Systemic EGF supplementation in these unilaterally obstructed rats also resulted in a decrease in the intensity of the DNA laddering pattern associated with renal tubular apoptosis. An in situ labeling procedure to identify apoptotic nuclei in the ureterally obstructed kidneys revealed a 50% reduction in apoptosis after EGF administration. Northern blot analysis and in situ hybridization for SGP-2 mRNA or clusterin gene product also revealed a decreased expression in the obstructed and EGF-treated renal parenchyma.Conclusions. These data suggest that EGF, apart from its known role as a mitogenic substance for renal tubular epithelial cells, is also a critical in vivo renal cell survival factor for the developmentally mature kidney. 相似文献
37.
38.
Monolayer cultures of normal human bone cells contain multiple subpopulations of alkaline phosphatase positive cells 总被引:5,自引:0,他引:5
Toshikatsu Matsuyama K. -H. William Lau Jon E. Wergedal 《Calcified tissue international》1990,47(5):276-283
Summary Cytochemical staining of normal human bone cells in monolayer cultures for alkaline phosphatase (ALP) indicated that the cultures
contained mixed-cell populations. Time course evaluations of the cytochemical staining revealed, in addition to the ALP-negative
cell population, at least two subpopulations of ALP-positive human bone cells with different levels of ALP. A cytochemical
method has been developed which separates the ALP-positive cells into high and intermediate ALP subpopulations. In this method,
human bone cells were stained for ALP using an azo-dye method and incubating at 4°C for 10 and 30 minutes, respectively. We
defined the cell population that stained positively for ALP at 10 minutes as strong ALP-positive cells, and both strong and
intermediate cells were stained at 30 minutes. The intermediate cells were determined from the difference between the values
at the two time points. The intra- and interassay variations of the assay, with the same investigator in blinded investigations,
were both less than 10% and the interobserver variation was approximately 25%. Analysis of the distribution of ALP levels
in cells with a laser densitometer confirmed the presence of at least three cell subpopulations. 1,25(OH)2D3 treatment increased the proportions of both ALP-positive cell populations, whereas TGF-beta treatment increased only the
intermediate ALP-positive cell population. On the contrary, fluoride increased the proportion of the strong ALP cells, and
IGF-1 had no effect on the proportions of either ALP-positive subpopulation. When the ALP-specific activity was compared with
the percentage of each ALP-positive subpopulations for the cells treated with effectors, the ALP-specific activity correlated
with the total ALP-positive and with the strong ALP-positive populations but not with the intermediate ALP-positive subpopulation.
In summary, this study represents the first evidence that normal human bone cells in monolayer cultures contained at least
two subpopulations of ALP-positive cells, and that bone cell effectors could have differential effects on each cell population. 相似文献
39.
Aaron H. Burstein Pharm.D. William G. Reiss Pharm.D. Eric Kantor B.A. Gail D. Anderson Ph.D. 《Pharmacotherapy》1998,18(6):1271-1276
Study Objective . To characterize cytochrome P450 (CYP) 3A4 activity in premenopausal and postmenopausal women by evaluating the urinary 6-β-hydroxycortisokcortisol ratio. Design . Prospective study. Subjects . Thirteen premenopausal and 13 postmenopausal women who were healthy and not receiving drugs known to affect CYP3A4 activity. Interventions . Beginning on day 2 of menses, premenopausal women collected first morning urine samples every other day for a complete menstrual cycle. Postmenopausal women collected first morning urine every other day for 28 days. Measurements and Main Results . Mean weekly 6-β-hydroxycortisol:cortisol ratios did not differ during the phase (week) of the menstrual cycle. Daily ratios did not differ in postmenopausal women. No difference between premenopausal and postmenopausal women was found on comparing overall median ratios. Conclusion . Cytochrome P450 3A4 activity as measured by 6-β-hydroxy cortisol:cortisol ratio did not differ by week of menstrual cycle, suggesting no menstrual cycle-related changes. Menopause does not appear to be associated with differences in CYP3A4 activity, compared with premenopause. 相似文献
40.
William Plummer 《The British journal of general practice》2002,52(482):766-767