首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   8402篇
  免费   444篇
  国内免费   59篇
耳鼻咽喉   44篇
儿科学   199篇
妇产科学   181篇
基础医学   862篇
口腔科学   129篇
临床医学   1018篇
内科学   1486篇
皮肤病学   65篇
神经病学   907篇
特种医学   268篇
外科学   837篇
综合类   172篇
一般理论   11篇
预防医学   1107篇
眼科学   143篇
药学   850篇
中国医学   9篇
肿瘤学   617篇
  2024年   27篇
  2023年   50篇
  2022年   82篇
  2021年   182篇
  2020年   119篇
  2019年   203篇
  2018年   193篇
  2017年   162篇
  2016年   193篇
  2015年   203篇
  2014年   276篇
  2013年   393篇
  2012年   602篇
  2011年   605篇
  2010年   320篇
  2009年   298篇
  2008年   519篇
  2007年   594篇
  2006年   590篇
  2005年   625篇
  2004年   577篇
  2003年   507篇
  2002年   472篇
  2001年   119篇
  2000年   92篇
  1999年   124篇
  1998年   111篇
  1997年   96篇
  1996年   76篇
  1995年   57篇
  1994年   44篇
  1993年   52篇
  1992年   39篇
  1991年   20篇
  1990年   28篇
  1989年   13篇
  1988年   26篇
  1987年   24篇
  1986年   25篇
  1985年   19篇
  1984年   21篇
  1983年   20篇
  1982年   19篇
  1981年   17篇
  1980年   10篇
  1979年   9篇
  1978年   6篇
  1977年   6篇
  1975年   8篇
  1973年   5篇
排序方式: 共有8905条查询结果,搜索用时 15 毫秒
991.
BackgroundThis paper summarizes a new report presenting the best available research about the impact of the liability environment on maternity care, and policy options for improving this environment. Improved understanding of these matters can help to transcend polarized discourse and guide policy intervention.MethodsWe used a best available evidence approach and drew on more recent empirical legal studies and health services research about maternity care and liability when available, and considered other studies when unavailable.FindingsThe best available research does not support a series of widely held beliefs about maternity care and liability, including the economic impact of liability insurance premiums on maternity care clinicians, the existence of extensive defensive maternity care practice, and the impact of limiting the size of awards for non-economic damages in a malpractice lawsuit. In the practice of an average maternity caregiver, negligent injury of mothers and newborns seems to occur more frequently than any claim and far more frequently than a payout or trial. Many important gaps in knowledge relating to maternity care and liability remain. Some improvement strategies are likely to be more effective than others.ConclusionsEmpirical research does not support many widely held beliefs about maternity care and liability. The liability system does not currently serve well childbearing women and newborns, maternity care clinicians, or those who pay for maternity care. A number of promising strategies might lead to a higher functioning liability system, whereas others are unlikely to contribute to needed improvements.  相似文献   
992.
The study hypothesis was that fasting glucose, insulin, fructosamine, C-reactive protein, and interleukin-6 decrease and adiponectin increases with daily flaxseed consumption in overweight or obese individuals with pre-diabetes. In this randomized, cross-over study overweight or obese men and postmenopausal women (n = 25) with pre-diabetes consumed 0, 13, or 26 g ground flaxseed for 12 weeks. Glucose, insulin, homeostatic model assessment (HOMA-IR), and normalized percent of α-linolenic fatty acid (ALA) were significantly different by treatment (multiple analysis of variance, P = .036, P = .013, P = .008, P = .024 respectively). Paired t tests showed glucose decreased on the 13 g intervention compared to the 0 g period [13g = −2.10 ± 1.66 mg/L (mean ± SEM), 0 g = 9.22 ± 4.44 mg/L, P = .036]. Insulin decreased on the 13 g intervention but not the 26 g (P = .021) and 0 g (P = .013) periods (13 g = −2.12 ± 1.00 mU/L, 26 g = 0.67 ± 0.84 mU/L, 0g = 1.20 ± 1.16 mU/L). HOMA-IR decreased on the 13 g period but not on the 26 g (P = .012) and 0 g (P = .008) periods (13g = −0.71 ± 0.31, 26g = 0.27 ± 0.24, 0g = 0.51 ± 0.35). The α-linolenic fatty acid decrease for the 0 g period was different than the 13 g (P = .024) and 26 g (P = .000) periods (13 g = 0.20 ± 0.04, 26g = 0.35 ± 0.07, 0g = −0.01 ± 0.07). Fructosamine, high sensitivity C-reactive protein, adiponectin, and high-sensitivity interleukin-6 had no significant differences. Flaxseed intake decreased glucose and insulin and improved insulin sensitivity as part of a habitual diet in overweight or obese individuals with pre-diabetes.  相似文献   
993.
Differential locational access to fast-food retailing between neighbourhoods of varying socioeconomic status has been suggested as a contextual explanation for the social distribution of diet-related mortality and morbidity. This New Zealand study examines whether neighbourhood access to fast-food outlets is associated with individual diet-related health outcomes. Travel distances to the closest fast-food outlet (multinational and locally operated) were calculated for all neighbourhoods and appended to a national health survey. Residents in neighbourhoods with the furthest access to a multinational fast-food outlet were more likely to eat the recommended intake of vegetables but also be overweight. There was no association with fruit consumption. Access to locally operated fast-food outlets was not associated with the consumption of the recommended fruit and vegetables or being overweight. Better neighbourhood access to fast-food retailing is unlikely to be a key contextual driver for inequalities in diet-related health outcomes in New Zealand.  相似文献   
994.
The protective role of two apple polyphenol extracts, Douglas‐FB (FB) and Douglas‐EF (EF), on gastric mucosal damage following aspirin ingestion was investigated in healthy rats. Polyphenol content of the apple extracts varied, with the EF extract having 20% w/w polyphenols and a high proportion of flavanols as epicatechin and procyanidin, whereas the FB extract comprised 12% w/w polyphenols, which were mostly flavonols as quercetin glycosides. Male Sprague–Dawley rats were allocated to control, FB and EF groups and fed the experimental diet during the 10‐day trial. Control treatment rats received 1 mL of deionised water, whereas apple polyphenol treatment group rats, FB and EF received a concentration of 10?2 m polyphenols in 1 mL deionised water daily via oral gavage. At the end of 10‐day feeding period, rats were fasted overnight, and the following morning, aspirin (200 mg/kg) was given by oral gavage. Four hours after aspirin administration, the animals were euthanised, and samples taken for analysis. Both apple polyphenol extracts significantly reduced the ulcer area, ulcer lesion index and gastric injury score. The glutathione in gastric mucosa was increased significantly in rats given FB apple extract. Despite their different polyphenol compositions, FB and EF apple extracts assisted in protecting the gastric mucosa following acute aspirin administration in rats. Copyright © 2014 John Wiley & Sons, Ltd.  相似文献   
995.
996.
Existing theories (e.g., acculturative stress theory) cannot adequately explain why mental disorders in immigrants are less prevalent than in non-immigrants. In this paper, the culture-gene co-evolutionary theory of mental disorders was utilized to generate a novel hypothesis that connection to heritage culture reduces the risk for mental disorders in immigrant children. Four groups of children aged 2–17 years were identified from the 2007 United States National Survey of Children’s Health: 1.5th generation immigrant children (n = 1378), 2nd generation immigrant children (n = 4194), foreign adoptees (n = 270), and non-immigrant children (n = 54,877). The 1.5th generation immigrant children’s connection to their heritage culture is stronger than or similar to the 2nd generation immigrants, while the foreign adoptees have little connection to their birth culture. Controlling for age, sex, family type and SES, the odds for having ADD/ADHD, Conduct Disorder, Anxiety Disorder, and Depression diagnosis were the lowest for the 1.5th generation immigrant children, followed by the 2nd generation immigrant children and the foreign adoptees. The foreign adoptees and non-adopted children were similar in the odds of having these disorders. Connection to heritage culture might be the underlying mechanism that explained recent immigrants’ lower rates of mental disorders.  相似文献   
997.
Objectives: Data related to the cost effectiveness of surgical interventions and catheter ablation is sparse. This model-based analysis assessed the clinical and economic trade-offs involved in using catheter ablation or the Cox maze procedure in treating patients with atrial fibrillation.

Methods: A deterministic model was developed to project 1 year and lifetime health-related outcomes, costs, quality-adjusted life years (QALYs) and cost effectiveness of each treatment in patients with atrial fibrillation. Using previously unpublished Inova Heart and Vascular Institute (IHVI) data for patients undergoing either procedure, 1 year cost and clinical efficacy inputs were estimated. This data was supplemented with published literature and used to estimate costs, utilities, mortality and likelihood of patient improvement. Results were reported as cost-effectiveness ratios in $/QALY. Sensitivity analyses were conducted to assess the robustness of results.

Results: Patients initially treated with a Cox maze procedure were estimated to have higher costs than those treated with catheter ablation, both after 1 year and over the lifetime. However, patients undergoing the Cox maze procedure also had lower rates of 1 year mortality than catheter ablation patients (3.5% vs. 8.5%) and the highest rate of improvement following treatment, resulting in higher QALYs (12.4 vs. 10.2). Compared to catheter ablation, the lifetime incremental cost-effectiveness ratio for the Cox maze surgical procedure was $12,794 per QALY gained. Without quality adjustment, the ratio was $11,315. Results were most sensitive to the likelihood of improvement following each intervention and the cost of the initial procedure.

Conclusions: At a societal willingness to pay of $100,000/QALY, Cox maze procedure was found to both increase overall and quality-adjusted survival and constitute an effective use of resources in patients with atrial fibrillation.  相似文献   

998.
We examined the association of income inequality measured at the metropolitan area (MA) and county levels with individual self-rated health. Individual-level data were drawn from 259,762 respondents to the March Current Population Survey in 1996 and 1998. Income inequality and average income were calculated from 1990 census data, the former using Gini coefficients. Multi-level logistic regression models were used. Controlling for sex, age, race, and individual-level household income, respondents living in high, medium-high, and medium-low income inequality MAs had odds ratios of fair/poor self-rated health of 1.20 (95% confidence interval 1.04-1.38), 1.07 (0.95-1.21), and 1.02 (0.91-1.15), respectively, compared to people living in the MAs with the lowest income inequality. However, we found only a small association of MA-level income inequality with fair/poor health when controlling further for average MA household income: odds ratios were 1.10 (0.95-1.28), 1.01 (0.89-1.14), and 1.00 (0.89-1.12), respectively. Likewise, we found only a small association of county-level income inequality with self-rated health although only 40.7% of the sample had an identified county on CPS data. Regarding the association of state-level income inequality with fair/poor health, we found the association to be considerably stronger among non-metropolitan (i.e. rural) compared to metropolitan residents.  相似文献   
999.
OBJECTIVES: To examine the self-reported influences on intern prescribing practice. DESIGN: Qualitative interviews with a cross-sectional cohort. PARTICIPANTS AND SETTING: Ten interns practising in two urban teaching hospitals in New South Wales, Australia. RESULTS: The interns identified a number of factors that improve their confidence and perceived competence and allow them to extend their existing skills. These were approachable, available and up-to-date teachers (most often registrars and subspecialty nurses and pharmacists); timely, relevant and practical teaching (such as interactive bedside teaching); concise and widely accepted resources (such as prescribing pocket guides); and a constructive manner on the part of senior staff for dealing with prescribing errors. Interns also identified influences that are detrimental to confidence, conflict with their perceptions of appropriate prescribing and inhibit learning and skills acquisition. These were unapproachable, physically and mentally remote teachers (most often consultants); theoretical, inconsistent and irrelevant teaching (such as grand rounds or didactic education sessions); inconsistent and inaccessible resources; and a confrontational and accusatory way of dealing with prescribing errors. The added pressures of time, hospital hierarchies and the indirect influence of drug company promotion also impeded acquisition of good prescribing habits. CONCLUSIONS: At a critical time in skills development, interns encounter many forces that can potentially impact on prescribing practices in both positive and negative ways. Our data contribute to the understanding of the multifaceted learning environment of interns and may be useful in providing a foundation for prescriber education programmes tailored to the specific needs of junior doctors.  相似文献   
1000.

Background

Afatinib is approved in the US, Europe, and several other regions for first-line treatment for epidermal growth factor receptor mutation-positive (EGFRm+) non-small-cell lung cancer (NSCLC).

Patients and Methods

Treatment-naive patients with advanced EGFRm+ NSCLC were randomized to afatinib (40 mg/d) versus cisplatin/pemetrexed (LUX-Lung 3 [LL3]) or cisplatin/gemcitabine (LUX-Lung 6 [LL6]), or versus gefitinib (250 mg/d; LUX-Lung 7 [LL7]). We report subgroup analyses according to age, including 65 years or older versus younger than 65 years (preplanned; LL3/LL6) and additional cutoffs up to 75 years and older (exploratory; LL7). Progression-free survival (PFS), overall survival (OS), and adverse events (AEs) were evaluated.

Results

Among the 134 of 345 (39%) and 86 of 364 (24%) patients aged 65 years and older in LL3 and LL6, median PFS was improved with afatinib versus chemotherapy (LL3: hazard ratio [HR], 0.64 [95% confidence interval (CI), 0.39-1.03]; LL6: HR, 0.16 [95% CI, 0.07-0.39]). Afatinib significantly improved OS versus chemotherapy in elderly patients with Del19+ NSCLC in LL3 (HR, 0.39 [95% CI, 0.19-0.80]). Among the 40 of 319 patients (13%) aged 75 years or older in LL7, median PFS (HR, 0.69 [95% CI, 0.33-1.44]) favored afatinib, consistent with the overall population. Afatinib-associated AEs in older patients were consistent with the overall populations.

Conclusions

Subgroup analyses of the LL3, LL6, and LL7 trials show that afatinib is an effective and tolerable treatment for patients with EGFRm+ NSCLC, independent of age.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号