全文获取类型
收费全文 | 725篇 |
免费 | 43篇 |
国内免费 | 46篇 |
专业分类
耳鼻咽喉 | 2篇 |
儿科学 | 65篇 |
妇产科学 | 20篇 |
基础医学 | 71篇 |
口腔科学 | 37篇 |
临床医学 | 98篇 |
内科学 | 188篇 |
皮肤病学 | 11篇 |
神经病学 | 21篇 |
特种医学 | 132篇 |
外科学 | 29篇 |
综合类 | 15篇 |
预防医学 | 39篇 |
眼科学 | 4篇 |
药学 | 53篇 |
1篇 | |
肿瘤学 | 28篇 |
出版年
2023年 | 5篇 |
2022年 | 5篇 |
2021年 | 5篇 |
2020年 | 2篇 |
2019年 | 6篇 |
2018年 | 12篇 |
2017年 | 12篇 |
2016年 | 12篇 |
2015年 | 18篇 |
2014年 | 25篇 |
2013年 | 31篇 |
2012年 | 11篇 |
2011年 | 15篇 |
2010年 | 27篇 |
2009年 | 23篇 |
2008年 | 7篇 |
2007年 | 46篇 |
2006年 | 24篇 |
2005年 | 11篇 |
2004年 | 8篇 |
2003年 | 4篇 |
2002年 | 10篇 |
2001年 | 6篇 |
2000年 | 7篇 |
1999年 | 15篇 |
1998年 | 44篇 |
1997年 | 53篇 |
1996年 | 54篇 |
1995年 | 45篇 |
1994年 | 30篇 |
1993年 | 30篇 |
1992年 | 5篇 |
1991年 | 14篇 |
1990年 | 9篇 |
1989年 | 17篇 |
1988年 | 27篇 |
1987年 | 24篇 |
1986年 | 15篇 |
1985年 | 18篇 |
1984年 | 7篇 |
1983年 | 12篇 |
1982年 | 9篇 |
1981年 | 9篇 |
1980年 | 12篇 |
1979年 | 3篇 |
1978年 | 5篇 |
1977年 | 10篇 |
1976年 | 4篇 |
1975年 | 4篇 |
1970年 | 3篇 |
排序方式: 共有814条查询结果,搜索用时 31 毫秒
51.
Understanding diet and energy balance as risk factors for breast, colon,
and other cancers requires information on the contribution of each factor
and of interactions among factors to cancer risk. Rodent models for breast
cancer provide extensive data on effects of dietary fat and calories,
energy balance, body weight gain, and physical activity on tumor
development. Analyses of the combined data from many studies have shown
clearly that quality and quantity of dietary fat and energy balance
contribute independently to increased mammary gland tumorigenesis. These
findings were seen in female rats fed diets high in fat (35-40% of
calories) compared to rats fed control diets, with approximately 10% of
calories as fat (Fay and Freedman, 1997, Breast Cancer Res. Treat. 46,
215-223). The methods used permit comparison of experimental and
epidemiological data, and they may be useful in extrapolating between
species and developing public health recommendations. In addition to the
contributions of lifetime-diet composition, intake, energy balance, and
physical activity to cancer risk, there are questions about the timing and
duration of alterations in these factors and about the "dose-response"
characteristics of cancer risk to the factors. Endocrine mechanisms may be
significant in mammary gland tumor risk, but experimental and
epidemiological data indicate that cancers at other sites, such as colon
and liver, also are influenced by the factors listed. Other diet and
lifestyle factors that influence energy, or specifically fat, metabolism
may also affect risk for cancers that are promoted by increased intake of
fat and calories. Studies of separate and interactive effects of dietary
fat, black tea, weight gain, and mammary gland tumorigenesis (Rogers, et
al, 1998, Carcinogenesis 19, 1269-1273) have been analyzed. Using
adjustment of carcinogenesis endpoints for body weight, tumor burden, and
latency, they were found to be related to weight gain within treatment
groups in 2 of 3 experiments.
相似文献
52.
John J. Treanor Brandon Essink Steven Hull Steven Reed Ruvim Izikson Peter Patriarca Karen L. Goldenthal Robert Kohberger Lisa M. Dunkle 《Vaccine》2013
Background
Expression of recombinant hemagglutinin (rHA) in insect cells represents a technology with proven efficacy in seasonal influenza and with the potential for a rapid response to the emergence of new, pandemic strains. We evaluated the safety and immunogenicity of rHA vaccine (H5/Indonesia/5/05) produced in SF+ insect cells using a baculovirus expression vector system (BEVS). The rHA vaccine was tested with and without the adjuvant glucopyranosyl lipid A/stable emulsion (GLA/SE).Methods
Healthy adults 18–49 were randomized to two IM doses on Days 0 and 21 of placebo; unadjuvanted rHA 135 μg or 45 μg, or rHA 45 μg, 15 μg, 7.5 μg or 3.8 μg with GLA/SE. A pioneer group was monitored through Day 42 before randomizing remaining subjects. H5-specific antibody was determined by hemagglutination inhibition (HAI) and microneutralization (MN) on Days 0, 21 and 42.Results
392 subjects were randomized, of whom 380 (97%) received two doses and 386 (98%) completed 12 months of follow-up. Injection site pain and tenderness were seen in 50–70% of rHA + GLA/SE recipients and 4–9% of rHA alone and placebo recipients, but most complaints were mild to moderate in intensity. After two doses, the proportions of subjects with HAI titers ≥1:40 were 32% and 15% in the unadjuvanted 135 μg and 45 μg groups, and 82%, 75%, 66%, and 72% in those receiving 45 μg, 15 μg, 7.5 μg, or 3.8 μg with GLA/SE. The geometric mean titers (GMTs) of HAI antibody on Day 42 were 128, 95, 69, and 72 in the 45 μg, 15 μg, 7.5 μg, or 3.8 μg with GLA/SE groups, respectively.Conclusions
rHA GLA/SE was well tolerated and immunogenic in healthy adults, and GLA/SE substantially improved the serum antibody response. rHA expressed using BEVS recombinant DNA platform technology represents a promising strategy for pandemic control. 相似文献53.
54.
Background
Postal questionnaires are an economical and simple method of data collection for research purposes but are subject to non-response bias. Several studies have explored the effect of monetary and non-monetary incentives on response. Recent meta-analyses conclude that financial incentives are an effective way of increasing response rates. However, large surveys rarely have the resources to reward individual participants. Three previous papers report on the effectiveness of lottery incentives with contradictory results. This study aimed to determine the effect of including a lottery-style incentive on response rates to a postal health survey.Methods
Randomised controlled trial. Setting: North and West Birmingham. 8,645 patients aged 18 or over randomly selected from registers of eight general practices (family physician practices). Intervention: Inclusion of a flyer and letter with a health questionnaire informing patients that returned questionnaires would be entered into a lottery-style draw for £100 of gift vouchers. Control: Health questionnaire accompanied only by standard letter of explanation. Main outcome measures: Response rate and completion rate to questionnaire.Results
5,209 individuals responded with identical rates in both groups (62.1%). Practice, patient age, sex and Townsend score (a postcode based deprivation measure) were identified as predictive of response, with higher response related to older age, being female and living in an area with a lower Townsend score (less deprived).Conclusion
This RCT, using a large community based sample, found that the offer of entry into a lottery style draw for £100 of High Street vouchers has no effect on response rates to a postal health questionnaire. 相似文献55.
56.
57.
58.
59.
Lower extremity deep venous thrombosis: evaluation with ferumoxytol-enhanced MR imaging and dual-contrast mechanism--preliminary experience 总被引:2,自引:0,他引:2
Li W Salanitri J Tutton S Dunkle EE Schneider JR Caprini JA Pierchala LN Jacobs PM Edelman RR 《Radiology》2007,242(3):873-881
Institutional review board approval and informed consent were obtained for this HIPAA-compliant study, whose purpose was to prospectively evaluate the use of a dual-contrast mechanism in conjunction with an iron oxide blood pool contrast agent, ferumoxytol, to depict deep venous thrombosis (DVT). Nine patients with lower extremity DVT detected with duplex ultrasonography (US) were imaged with magnetic resonance (MR) imaging and ferumoxytol. Three techniques, including precontrast two-dimensional time-of-flight (TOF) imaging, ferumoxytol-enhanced bright-blood imaging, and ferumoxytol-enhanced dark-blood imaging, were applied. Image quality for precontrast and ferumoxytol-enhanced images was analyzed by using a four-point scale. Thrombus was depicted as a filling defect within the blood pool on bright-blood images and as bright tissue that appeared highly contrasted against a dark background on dark-blood images. Image quality of ferumoxytol-enhanced images was uniformly superior to that of precontrast TOF images (P = .007). Compared with precontrast TOF images, ferumoxytol-enhanced bright-blood images had higher contrast-to-noise ratios (CNRs) between thrombus and blood (P = .051), whereas ferumoxytol-enhanced dark-blood images showed significantly higher CNRs between thrombus and surrounding muscle (P = .008). Ferumoxytol-enhanced MR imaging can depict DVT with a dual-contrast mechanism and show the extent of thrombus. 相似文献
60.
Noelene K. Jeffers PhD CNM IBCLC Lucinda Canty PhD CNM FACNM Michelle Drew DNP MPH CNM FNP-C FACNM Nikia Grayson DNP MPH MA CNM FNP-C Jamarah Amani LM Ebony Marcelle DNP CNM FACNM Alexis Dunn Amore PhD CNM FACNM FAAN 《分娩》2023,50(2):267-272
Racial concordance has been identified as a potential strategy to improve the perinatal health of Black women and birthing people by mitigating implicit bias and improving mutual trust, healthy communication, and satisfaction. In a recent article published in BIRTH: Issues in Perinatal Care, Bogdan-Lovis et al. surveyed 200 Black women to determine whether they possessed a race and gender practitioner preference for their birth practitioner and examined whether race and gender concordance was associated with greater birth satisfaction and perceived respect, trust, practitioner competence, empathy, and use of inclusive communication. In this commentary, written by a group of Black midwives, we respond to the study and offer a vision for race-concordant care that encompasses cultural safety provided in a community-based setting. 相似文献