全文获取类型
收费全文 | 33282篇 |
免费 | 2372篇 |
国内免费 | 55篇 |
专业分类
耳鼻咽喉 | 304篇 |
儿科学 | 1190篇 |
妇产科学 | 972篇 |
基础医学 | 4282篇 |
口腔科学 | 436篇 |
临床医学 | 4365篇 |
内科学 | 5992篇 |
皮肤病学 | 473篇 |
神经病学 | 3560篇 |
特种医学 | 603篇 |
外国民族医学 | 4篇 |
外科学 | 2977篇 |
综合类 | 329篇 |
一般理论 | 45篇 |
预防医学 | 4634篇 |
眼科学 | 507篇 |
药学 | 2216篇 |
中国医学 | 23篇 |
肿瘤学 | 2797篇 |
出版年
2024年 | 78篇 |
2023年 | 293篇 |
2022年 | 518篇 |
2021年 | 1121篇 |
2020年 | 683篇 |
2019年 | 1038篇 |
2018年 | 1159篇 |
2017年 | 833篇 |
2016年 | 980篇 |
2015年 | 1008篇 |
2014年 | 1336篇 |
2013年 | 1874篇 |
2012年 | 2739篇 |
2011年 | 2967篇 |
2010年 | 1551篇 |
2009年 | 1300篇 |
2008年 | 2380篇 |
2007年 | 2378篇 |
2006年 | 2182篇 |
2005年 | 2049篇 |
2004年 | 1830篇 |
2003年 | 1578篇 |
2002年 | 1596篇 |
2001年 | 207篇 |
2000年 | 172篇 |
1999年 | 204篇 |
1998年 | 307篇 |
1997年 | 238篇 |
1996年 | 169篇 |
1995年 | 179篇 |
1994年 | 135篇 |
1993年 | 119篇 |
1992年 | 71篇 |
1991年 | 47篇 |
1990年 | 51篇 |
1989年 | 45篇 |
1988年 | 44篇 |
1987年 | 36篇 |
1986年 | 33篇 |
1985年 | 16篇 |
1984年 | 19篇 |
1983年 | 29篇 |
1982年 | 24篇 |
1981年 | 18篇 |
1980年 | 11篇 |
1977年 | 6篇 |
1976年 | 6篇 |
1974年 | 6篇 |
1973年 | 7篇 |
1942年 | 4篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
Lisa Lighthall Haubert Sara J. Mulroy Philip S. Requejo Somboon Maneekobkunwong JoAnne K. Gronley Jeffery W. Rankin 《The journal of spinal cord medicine》2020,43(5):594-606
Objective: Shoulder pain after spinal cord injury (SCI) is attributed to increased mobility demands on the arms and negatively impacts independence and quality of life. Repetitive superior and posterior shoulder joint forces produced during traditional wheelchair (WC) locomotion can result in subacromial impingement if unopposed, as with muscular fatigue or weakness. ROWHEELS® (RW), geared rear wheels that produce forward WC movement with backward rim pulling, could alter these forces. Design: Cross sectional. Setting: Research laboratory at a rehabilitation hospital. Participants: Ten manual WC users with paraplegia. Outcome measures: Propulsion characteristics and right upper extremity/trunk kinematics and shoulder muscle activity were collected during ergometer propulsion: (1) self-selected free speed reverse propulsion with RW, (2) matched-speed reverse (rSW), and (3) forward propulsion (fSW) with instrumented Smartwheels (SW). Inverse dynamics using right-side SW rim kinetics and kinematics compared shoulder kinetics during rSW and fSW. Results: Free propulsion velocity, cycle distance and cadence were similar during RW, rSW and fSW. Overall shoulder motion was similar except that peak shoulder extension was significantly reduced in both RW and rSW versus fSW. Anteriorly and inferiorly directed SW rim forces were decreased during rSW versus fSW propulsion, but posteriorly and superiorly directed rim forces were significantly greater. Superior and posterior shoulder joint forces and flexor, adductor, and external rotation moments were significantly less during rSW, without a significant difference in net shoulder forces and moments. Traditional propulsive-phase muscle activity was significantly reduced and recovery-phase muscle activity was increased during reverse propulsion. Conclusion: These results suggest that reverse propulsion may redirect shoulder demands and prevent subacromial impingement, thereby preventing injury and preserving independent mobility for individuals with paraplegia. 相似文献
2.
Lisa I. Iezzoni Amy J. Wint Alexy Arauz Boudreau Cheri A. Blauwet Karen A. Kuhlthau 《Disability and health journal》2018,11(3):405-411
Background
Few U.S. studies have explored how children experience a parent's mobility disability and its effects on their daily lives.Objective
We aimed to engage youth ages 13–17 who had at least one parent with mobility disability in describing their perceptions of their parent's disability and its consequences for their daily and family life.Methods
Participants videoed and photographed their experiences following general guidelines from the researchers about topics of interest. Participants made their own choices about what they submitted. We used conventional content analysis to identify broad themes.Results
The mean (standard deviation) age of the 10 participants was 15.2 (1.9) years; 5 were male; 9 participants were white. All 5 girls submitted multiple self-focused (selfie) videos made in their bedrooms; the 5 boys submitted more diverse data files. Several broad themes or topics emerged including: the effects of timing and trajectory of the parent's disability; perceptions of early maturity and responsibility; fears and frustrations relating to the parent's disability; support and emerging resilience; and sense of social justice. Participants generally felt their parents' disability made them become – compared to their peers – more mature, responsible, capable of performing household tasks, and aware of disability civil rights.Conclusions
Participants raised many issues that health care providers should be aware of when youth have parents with mobility disability. A parent's mobility disability may be associated with resilience but also may pose challenges for youth. More research is needed to understand better adolescents' experiences and how clinicians might best assist these youth. 相似文献3.
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4.
Lindsey Haynes-Maslow Lauri Andress Stephanie Jilcott Pitts Isabel Osborne Barbara Baquero Lisa Bailey-Davis Carmen Byker-Shanks Bailey Houghtaling Jane Kolodinsky Brian K. Lo Emily H. Morgan Emily Piltch Elaine Prewitt Rebecca A. Seguin Alice S. Ammerman 《Journal of the Academy of Nutrition and Dietetics》2018,118(9):1664-1672
Background
In 2016, the US Department of Agriculture (USDA)’s Supplemental Nutrition Assistance Program (SNAP) Retailer Rule proposed several changes for SNAP-authorized retailers, including: requiring retailers to have at least 85% of their food sales come from items that are not cooked or heated on site before or after purchase; requiring stores to stock seven varieties of qualifying foods from four staple food groups; requiring stores to carry perishable foods in three of the four staple groups; requiring stores to carry six units of qualifying foods at all times (depth of stock); disqualifying multiple ingredient foods and accessory foods from counting toward depth of stock requirements.Objectives
To better understand arguments used to support or oppose the USDA’s proposed rule that all SNAP-authorized retailers carry more nutritious foods.Design
We conducted a qualitative content analysis of a random sample of public comments posted to the US Federal Register (a publicly available database) in response to the USDA’s proposed rule.Participants/setting
A random sample of 20% of all public comments submitted by individuals and organizations to the US Federal Register were analyzed (n=303) for this study.Results
Three main themes were discussed: 1) arguments used in opposition to the rule; 2) arguments used in support of the rule; and 3) facilitators to assist stores in implementing the rule. Some of the subthemes included focusing on definitions used in the rule, reduced food access caused by stores leaving the SNAP program, lack of space and equipment for healthy foods, and the potential for increasing healthy food access.Conclusions
Nutrition and dietetics practitioners may be tasked with working with stores to implement healthy changes. Nutrition and dietetics practitioners must understand the role that the USDA has in food policy. In addition, understanding how federal food policy influences the environments in which dietetics professionals’ clients are making food choices is important. 相似文献5.
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
6.
Lisa Ying Fuyu Song Shein-Chung Chow Xiaodong Li 《Journal of biopharmaceutical statistics》2018,28(5):840-856
In recent years, multi-regional clinical trials (MRCT) that conduct clinical trials simultaneously in Asian Pacific region, Europe, and the United States have become very popular for global pharmaceutical development. The main purpose of multi-regional clinical trials is to shorten the time for pharmaceutical development and regulatory submission, and approval around the world. In practice, however, clinical results observed from some regions (sub-population) may not be consistent with the results from other regions and/or all regions combined (entire population). The inconsistency observed may be due to ethnic differences in different regions, differences in medical practice, time points of assessment, or by random chance due to small sample size for the region. Some regional regulatory agencies require consistency evaluation between local country results and overall results. However, the challenge is there is no detailed guidance on the definition of ‘consistency’ and methodology to evaluate it. Therefore, the questions are: how to evaluate consistency and what statistical methods are appropriate to be used for consistency evaluation? In this article, several statistical tests for consistency (similarity) between clinical results observed from a specific sub-population and the entire population are proposed. These methods are compared through extensive simulation. As most published articles discussed consistency evaluation for superiority situations, we have discussed consistency evaluation for non-inferiority situation in this article through a simulated example concerning consistency in some countries. Recommendations of the statistical methods to be used for consistency evaluation are given. Other aspects that should be considered for consistency evaluation are also provided. 相似文献
7.
8.
9.
10.
Lisa P. Spees Paul L. Martin Joanne Kurtzberg Andre Stokhuyzen Lauren McGill Vinod K. Prasad Timothy A. Driscoll Suhag H. Parikh Kristin M. Page Richard Vinesett Christopher Severyn Anthony D. Sung Alan D. Proia Kirsten Jenkins Mehreen Arshad William J. Steinbach Patrick C. Seed Matthew S. Kelly 《Biology of blood and marrow transplantation》2019,25(4):756-763
Infections and graft-versus-host disease (GVHD) have historically resulted in high mortality among children undergoing umbilical cord blood transplantation (UCBT). However, recent advances in clinical practice have likely improved outcomes of these patients. We conducted a retrospective cohort study of children (<18years of age) undergoing UCBT at Duke University between January 1, 1995 and December 31, 2014. We compared 2-year all-cause and cause-specific mortality during 3 time periods based on year of transplantation (1995 to 2001, 2002 to 2007, and 2008 to 2014). We used multivariable Cox regression to identify demographic and UCBT characteristics that were associated with all-cause mortality, transplantation-related mortality, and death from invasive aspergillosis after adjustment for time period. During the 20-year study period 824 children underwent UCBT. Two-year all-cause mortality declined from 48% in 1995 to 2001 to 30% in 2008 to 2014 (P?=?.0002). White race and nonmalignant UCBT indications were associated with lower mortality. Black children tended to have a higher risk of death for which GVHD (18% versus 11%; P?=?.06) or graft failure (9% versus 3%; P?=?.01) were contributory than white children. Comparing 2008 to 2014 with 1995 to 2001, more than half (59%) of the reduced mortality was attributable to a reduction in infectious mortality, with 45% specifically related to reduced mortality from invasive aspergillosis. Antifungal prophylaxis with voriconazole was associated with lower mortality from invasive aspergillosis than low-dose amphotericin B lipid complex (hazard ratio, .09; 95% confidence interval, .01 to .76). With the decline in mortality from invasive aspergillosis, adenovirus and cytomegalovirus have become the most frequentinfectious causes of death in children after UCBT. Advances in clinical practice over the past 20years improved survival of children after UCBT. Reduced mortality from infections, particularly invasive aspergillosis, accounted for the largest improvement in survival and was associated with use of voriconazole for antifungal prophylaxis. 相似文献