全文获取类型
收费全文 | 2913361篇 |
免费 | 218760篇 |
国内免费 | 5421篇 |
专业分类
耳鼻咽喉 | 42943篇 |
儿科学 | 88448篇 |
妇产科学 | 78395篇 |
基础医学 | 409657篇 |
口腔科学 | 84182篇 |
临床医学 | 262490篇 |
内科学 | 562382篇 |
皮肤病学 | 58861篇 |
神经病学 | 243585篇 |
特种医学 | 116086篇 |
外国民族医学 | 1042篇 |
外科学 | 440524篇 |
综合类 | 72566篇 |
现状与发展 | 3篇 |
一般理论 | 1168篇 |
预防医学 | 233918篇 |
眼科学 | 69581篇 |
药学 | 216371篇 |
67篇 | |
中国医学 | 5377篇 |
肿瘤学 | 149896篇 |
出版年
2018年 | 28702篇 |
2016年 | 24662篇 |
2015年 | 27883篇 |
2014年 | 40240篇 |
2013年 | 61408篇 |
2012年 | 82671篇 |
2011年 | 87156篇 |
2010年 | 51300篇 |
2009年 | 49047篇 |
2008年 | 82701篇 |
2007年 | 88601篇 |
2006年 | 89207篇 |
2005年 | 87082篇 |
2004年 | 84284篇 |
2003年 | 81393篇 |
2002年 | 80128篇 |
2001年 | 129995篇 |
2000年 | 134482篇 |
1999年 | 113881篇 |
1998年 | 33471篇 |
1997年 | 30551篇 |
1996年 | 30124篇 |
1995年 | 29127篇 |
1994年 | 27443篇 |
1993年 | 25567篇 |
1992年 | 93013篇 |
1991年 | 89773篇 |
1990年 | 86888篇 |
1989年 | 83706篇 |
1988年 | 78013篇 |
1987年 | 77022篇 |
1986年 | 72863篇 |
1985年 | 69939篇 |
1984年 | 53439篇 |
1983年 | 45713篇 |
1982年 | 28236篇 |
1981年 | 25242篇 |
1980年 | 23762篇 |
1979年 | 51270篇 |
1978年 | 36321篇 |
1977年 | 30596篇 |
1976年 | 28596篇 |
1975年 | 30329篇 |
1974年 | 37520篇 |
1973年 | 35866篇 |
1972年 | 33635篇 |
1971年 | 31076篇 |
1970年 | 29400篇 |
1969年 | 27647篇 |
1968年 | 25148篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
Lisa Daniels Rachael W. Taylor Sheila M. Williams Rosalind S. Gibson Samir Samman Benjamin J. Wheeler Barry J. Taylor Elizabeth A. Fleming Nicola K. Hartley Anne-Louise M. Heath 《Journal of the Academy of Nutrition and Dietetics》2018,118(6):1006-1016.e1
Background
Little is known about zinc intakes and status during complementary feeding. This is particularly true for baby-led approaches, which encourage infants to feed themselves from the start of complementary feeding, although self-feeding may restrict the intake of zinc-rich foods.Objective
To determine the zinc intakes, sources, and biochemical zinc status of infants following Baby-Led Introduction to SolidS (BLISS), a modified version of Baby-Led Weaning (BLW), compared with traditional spoon-feeding.Design
Secondary analysis of the BLISS randomized controlled trial.Participants/setting
Between 2012 and 2014, 206 community-based participants from Dunedin, New Zealand were randomized to a Control or BLISS group.Intervention
BLISS participants received eight study visits (antenatal to 9 months) providing education and support regarding BLISS (ie, infant self-feeding from 6 months with modifications to address concerns about iron, choking, and growth).Main outcome measures
Dietary zinc intakes at 7 and 12 months (weighed 3-day diet records) and zinc status at 12 months (plasma zinc concentration).Statistical analyses performed
Regression analyses were used to investigate differences in dietary intakes and zinc status by group, adjusted for maternal education and parity and infant age and sex.Results
There were no significant differences in zinc intakes between BLISS and Control infants at 7 (median: 3.5 vs 3.5 mg/day; P=0.42) or 12 (4.4 vs 4.4 mg/day; P=0.86) months. Complementary food groups contributing the most zinc at 7 months were “vegetables” for Control infants, and “breads and cereals” for BLISS infants, then “dairy” for both groups at 12 months. There was no significant difference in mean±standard deviation plasma zinc concentration between the Control (62.8±9.8 μg/dL [9.6±1.5 μmol/L]) and BLISS (62.8±10.5 μg/dL [9.6±1.6 μmol/L]) groups (P=0.75).Conclusions
BLISS infants achieved similar zinc intake and status to Control infants. However, the BLISS intervention was modified to increase iron intake, which may have improved zinc intake, so these results should not be generalized to infants following unmodified BLW. 相似文献102.
Laura A. Smith Ciara H. O’Flanagan Laura W. Bowers Emma H. Allott Stephen D. Hursting 《Journal of the Academy of Nutrition and Dietetics》2018,118(4):652-667
Prevalence of obesity, an established risk factor for many cancers, has increased dramatically over the past 50 years in the United States and across the globe. Relative to normoweight cancer patients, obese cancer patients often have poorer prognoses, resistance to chemotherapies, and are more likely to develop distant metastases. Recent progress on elucidating the mechanisms underlying the obesity?cancer connection suggests that obesity exerts pleomorphic effects on pathways related to tumor development and progression and, thus, there are multiple opportunities for primary prevention and treatment of obesity-related cancers. Obesity-associated alterations, including systemic metabolism, adipose inflammation, growth factor signaling, and angiogenesis, are emerging as primary drivers of obesity-associated cancer development and progression. These obesity-associated host factors interact with the intrinsic molecular characteristics of cancer cells, facilitating several of the hallmarks of cancer. Each is considered in the context of potential preventive and therapeutic strategies to reduce the burden of obesity-related cancers. In addition, this review focuses on emerging mechanisms behind the obesity?cancer link, as well as relevant dietary interventions, including calorie restriction, intermittent fasting, low-fat diet, and ketogenic diet, that are being implemented in preclinical and clinical trials, with the ultimate goal of reducing incidence and progression of obesity-related cancers. 相似文献
103.
104.
Camila L.P. Oliveira Stephanie Mattingly Ralf Schirrmacher Michael B. Sawyer Eugene J. Fine Carla M. Prado 《Journal of the Academy of Nutrition and Dietetics》2018,118(4):668-688
The predominant use of glucose anaerobically by cancer cells (Warburg effect) may be the most important characteristic the majority of these cells have in common and, therefore, a potential metabolic pathway to be targeted during cancer treatment. Because this effect relates to fuel oxidation, dietary manipulation has been hypothesized as an important strategy during cancer treatment. As such, the concept of a ketogenic diet (KD) in cancer emerged as a metabolic therapy (ie, targeting cancer cell metabolism) rather than a dietary approach. The therapeutic mechanisms of action of this high-fat, moderate-to-low protein, and very-low-carbohydrate diet may potentially influence cancer treatment and prognosis. Considering the lack of a dietetics-focused narrative review on this topic, we compiled the evidence related to the use of this diet in humans with diverse cancer types and stages, also focusing on the nutrition and health perspective. The use of KD in cancer shows potentially promising, but inconsistent, results. The limited number of studies and differences in study design and characteristics contribute to overall poor quality evidence, limiting the ability to draw evidence-based conclusions. However, the potential positive influences a KD may have on cancer treatment justify the need for well-designed clinical trials to better elucidate the mechanisms by which this dietary approach affects nutritional status, cancer prognosis, and overall health. The role of registered dietitian nutritionists is demonstrated to be crucial in planning and implementing KD protocols in oncology research settings, while also ensuring patients’ adherence and optimal nutritional status. 相似文献
105.
106.
Joseph J. Knapik Krista G. Austin Emily K. Farina Harris R. Lieberman 《Journal of the Academy of Nutrition and Dietetics》2018,118(8):1370-1388
Background
Dietary supplement (DS) use is prevalent among the US Armed Forces personnel, but representative cross-service comparisons and characteristics of personnel using DSs are limited.Objective
Examine DS use and characteristics associated with use in a representative sample of US Armed Forces personnel (Army, Navy, Air Force, Marine Corps, and Coast Guard) using data from the 2011 Department of Defense Survey of Health-Related Behaviors.Design and participants
A stratified random sample of service members (SMs) was contacted and asked to complete a questionnaire assessing personal characteristics and DS use.Results
Overall, 69% of the 39,877 SMs reported using DSs ≥1 time per week. The most commonly used DSs were multivitamin or multiminerals (50%), antioxidants (34%), individual vitamins or minerals (33%), bodybuilding supplements (27%), fish oils (26%), herbals (16%), and weight-loss supplements (16%). Multiple logistic regression indicated overall DS use was higher among women, those with higher educational levels, Marine Corps SMs, officers, those with higher body mass index, those engaged in greater physical activity and weight training, and people in weight control programs. DS use was lower when peer groups or leadership discouraged substance abuse.Conclusions
DS use was considerably higher in the US Armed Forces compared with civilian populations, although many demographic and lifestyle factors associated with use were similar. Some categories of DSs extensively used by SMs such as bodybuilding supplements have been associated with adverse events. Discouraging substance abuse through peer groups and leadership actions may reduce use of unnecessary or dangerous DSs. 相似文献107.
Qian Zhang Yunmei Song Stephen W. Page Sanjay Garg 《Journal of pharmaceutical sciences》2018,107(2):587-594
The transdermal delivery of 2 fluorescent probes with similar molecular weight but different lipophilicity, into and through the skin from 2 commercially available transdermal bases, pluronic lecithin organogel, and Lipoderm® has been evaluated. First, in vitro penetration of fluorescein sodium and fluorescein (free acid) through porcine skin was evaluated. Retention and depth distribution profiles in skin were obtained by tape stripping and then followed by optical sectioning using multiphoton microscopy. The results showed that Lipoderm® led to an enhanced penetration of the hydrophilic compound, fluorescein sodium. For the lipophilic compound fluorescein (free acid), Lipoderm® performed similar to pluronic lecithin organogel base, where minimal drug was detected in either receptor phase. The skin retention and depth distribution results also showed that the hydrophilic fluorescein sodium had high skin retention with Lipoderm®, whereas fluorescein (free acid) had very low penetration and retention with increasing skin depth. Moreover, optical sectioning by multiphoton microscopy revealed an uneven distribution of probes across the skin in the x-y plane for both transdermal bases. This work showed that a hydrophilic compound has significantly increased skin penetration and retention when formulated with Lipoderm®, and the skin retention of the probe was the main determinant of its skin flux. 相似文献
108.
109.
Ronald T. Toth Samantha E. Pace Brittney J. Mills Sangeeta B. Joshi Reza Esfandiary C. Russell Middaugh David D. Weis David B. Volkin 《Journal of pharmaceutical sciences》2018,107(4):1009-1019
Antibodies are molecules that exhibit diverse conformational changes on different timescales, and there is ongoing interest to better understand the relationship between antibody conformational dynamics and storage stability. Physical stability data for an IgG4 monoclonal antibody (mAb-D) were gathered through traditional forced degradation (temperature and stirring stresses) and accelerated stability studies, in the presence of different additives and solution conditions, as measured by differential scanning calorimetry, size exclusion chromatography, and microflow imaging. The results were correlated with hydrogen exchange mass spectrometry (HX-MS) data gathered for mAb-D in the same formulations. Certain parameters of the HX-MS data, including hydrogen exchange in specific peptide segments in the CH2 domain, were found to correlate with stabilization and destabilization of additives on mAb-D during thermal stress. No such correlations between mAb physical stability and HX-MS readouts were observed under agitation stress. These results demonstrate that HX-MS can be set up as a streamlined methodology (using minimal material and focusing on key peptide segments at key time points) to screen excipients for their ability to physically stabilize mAbs. However, useful correlations between HX-MS and either accelerated or real-time stability studies will be dependent on a particular mAb's degradation pathway(s) and the type of stresses used. 相似文献
110.
Lisa A. McConnachie Loren M. Kinman Josefin Koehn John C. Kraft Sarah Lane Wonsok Lee Ann C. Collier Rodney J.Y. Ho 《Journal of pharmaceutical sciences》2018,107(7):1787-1790
Daily oral antiretroviral therapy regimens produce limited drug exposure in tissues where residual HIV persists and suffer from poor patient adherence and disparate drug kinetics, which all negatively impact outcomes. To address this, we developed a tissue- and cell-targeted long-acting 4-in-1 nanosuspension composed of lopinavir (LPV), ritonavir, tenofovir (TFV), and lamivudine (3TC). In 4 macaques dosed subcutaneously, drug levels over 5 weeks in plasma, lymph node mononuclear cells (LNMCs), and peripheral blood mononuclear cells (PBMCs) were analyzed by liquid chromatography–tandem mass spectrometry. Plasma and PBMC levels of the active drugs (LPV, TFV, and 3TC) were sustained for 5 weeks; PBMC exposures to LPV, ritonavir, and 3TC were 12-, 16-, 42-fold higher than those in plasma. Apparent T1/2z of LPV, TFV, and 3TC were 219.1, 63.1, and 136.3 h in plasma; 1045.7, 105.9, and 127.7 h in PBMCs. At day 8, LPV, TFV, and 3TC levels in LNMCs were 4.1-, 5.0-, and 1.9-fold higher than in those in PBMCs and much higher than in plasma. Therefore, 1 dose of a 4-drug nanosuspension exhibited persistent drug levels in LNMCs, PBMCs, and plasma for 5 weeks. With interspecies scaling and dose adjustment, this 4-in-1 HIV drug-combination could be a long-acting treatment with the potential to target residual virus in tissues and improve patient adherence. 相似文献