全文获取类型
收费全文 | 1521296篇 |
免费 | 93255篇 |
国内免费 | 4298篇 |
专业分类
耳鼻咽喉 | 18196篇 |
儿科学 | 50327篇 |
妇产科学 | 39602篇 |
基础医学 | 214735篇 |
口腔科学 | 37663篇 |
临床医学 | 142472篇 |
内科学 | 289938篇 |
皮肤病学 | 27445篇 |
神经病学 | 128100篇 |
特种医学 | 57034篇 |
外国民族医学 | 366篇 |
外科学 | 213282篇 |
综合类 | 31293篇 |
现状与发展 | 1篇 |
一般理论 | 480篇 |
预防医学 | 131520篇 |
眼科学 | 31988篇 |
药学 | 108562篇 |
36篇 | |
中国医学 | 3844篇 |
肿瘤学 | 91965篇 |
出版年
2021年 | 11671篇 |
2019年 | 12554篇 |
2018年 | 36936篇 |
2017年 | 28580篇 |
2016年 | 31712篇 |
2015年 | 16384篇 |
2014年 | 21970篇 |
2013年 | 33321篇 |
2012年 | 51537篇 |
2011年 | 67168篇 |
2010年 | 44832篇 |
2009年 | 36077篇 |
2008年 | 61416篇 |
2007年 | 65921篇 |
2006年 | 46308篇 |
2005年 | 46158篇 |
2004年 | 45317篇 |
2003年 | 44029篇 |
2002年 | 41036篇 |
2001年 | 61232篇 |
2000年 | 63027篇 |
1999年 | 52579篇 |
1998年 | 14868篇 |
1997年 | 13534篇 |
1996年 | 13245篇 |
1995年 | 12607篇 |
1994年 | 11770篇 |
1993年 | 11035篇 |
1992年 | 41689篇 |
1991年 | 40940篇 |
1990年 | 39642篇 |
1989年 | 37489篇 |
1988年 | 34715篇 |
1987年 | 33808篇 |
1986年 | 32256篇 |
1985年 | 30744篇 |
1984年 | 23128篇 |
1983年 | 19671篇 |
1982年 | 11848篇 |
1979年 | 20878篇 |
1978年 | 14887篇 |
1977年 | 12126篇 |
1976年 | 11921篇 |
1975年 | 12157篇 |
1974年 | 14863篇 |
1973年 | 14506篇 |
1972年 | 13398篇 |
1971年 | 12456篇 |
1970年 | 11533篇 |
1969年 | 10465篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
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
72.
Conrad M. Tobert Sarah L. Mott Kenneth G. Nepple 《Journal of the Academy of Nutrition and Dietetics》2018,118(1):125-131
Background
Malnutrition is a significant problem for hospitalized patients. However, the true prevalence of reported malnutrition diagnosis in real-world clinical practice is largely unknown. Using a large collaborative multi-institutional database, the rate of malnutrition diagnosis was assessed and used to assess institutional variables associated with higher rates of malnutrition diagnosis.Objective
The aim of this study was to define the prevalence of malnutrition diagnosis reported among inpatient hospitalizations.Design
The University Health System Consortium (Vizient) database was retrospectively reviewed for reported rates of malnutrition diagnosis.Participants/setting
All adult inpatient hospitalization at 105 member institutions during fiscal years 2014 and 2015 were evaluated.Main outcome measures
Malnutrition diagnosis based on the presence of an International Classification of Diseases-Ninth Revision diagnosis code.Statistical analysis
Hospital volume and publicly available hospital rankings and patient satisfaction scores were obtained. Multiple regression analysis was performed to assess the association between these variables and reported rates of malnutrition.Results
A total of 5,896,792 hospitalizations were identified from 105 institutions during the 2-year period. It was found that 292,754 patients (5.0%) had a malnutrition diagnosis during their hospital stay. By institution, median rate of malnutrition diagnosis during hospitalization was 4.0%, whereas the rate of severe malnutrition diagnosis was 0.9%. There was a statistically significant increase in malnutrition diagnosis from 4.0% to 4.9% between 2014 and 2015 (P<0.01). Institutional factors associated with increased diagnosis of malnutrition were higher hospital volume, hospital ranking, and patient satisfaction scores (P<0.01).Conclusions
Missing a malnutrition diagnosis appears to be a universal issue because the rate of malnutrition diagnosis was consistently low across academic medical centers. Institutional variables were associated with the prevalence of malnutrition diagnosis, which suggests that institutional culture influences malnutrition diagnosis. Quality improvement efforts aimed at improved structure and process appear to be needed to improve the identification of malnutrition. 相似文献73.
74.
Bo Feng Angela C. Doran Li Di Mark A. West Sarah M. Osgood Jessica Y. Mancuso Christopher L. Shaffer Larry Tremaine Jennifer Liras 《Journal of pharmaceutical sciences》2018,107(8):2225-2235
Four P-glycoprotein (P-gp) and breast cancer resistance protein (BCRP) substrates with human cerebrospinal fluid (CSF) concentrations and preclinical neuropharmacokinetics were used to assess in vitro–in vivo extrapolation of brain penetration in preclinical species and the ability to predict human brain penetration. Unbound brain (Cb,u), unbound plasma (Cp,u), and CSF compound concentrations (CCSF) were measured in rats and nonhuman primates (NHPs), and the unbound partition coefficients (Cb,u/Cp,u and CCSF/Cp,u) were used to assess brain penetration. The results indicated that for P-gp and BCRP dual substrates, brain penetration was severally impaired in all species. In comparison, for P-gp substrates that are weak or non-BCRP substrates, improved brain penetration was observed in NHPs and humans than in rats. Overall, NHP appears to be more predictive of human brain penetration for P-gp substrates with weak or no interaction with BCRP than rat. Although CCSF does not quantitatively correspond to Cb,u for efflux transporter substrates, it is mostly within 3-fold higher of Cb,u in rat and NHP, suggesting that CCSF can be used as a surrogate for Cb,u. Taken together, a holistic approach including both in vitro transporter and in vivo neuropharmacokinetics data enables a better estimation of human brain penetration of P-gp/BCRP substrates. 相似文献
75.
Verônica M. Couto Maria J. Prieto Daniela E. Igartúa Daniela A. Feas Lígia N.M. Ribeiro Camila M.G. Silva Simone R. Castro Viviane A. Guilherme Darlene D. Dantzger Daisy Machado Silvia del V. Alonso Eneida de Paula 《Journal of pharmaceutical sciences》2018,107(9):2411-2419
Administration of local anesthetics is one of the most effective pain control techniques for postoperative analgesia. However, anesthetic agents easily diffuse into the injection site, limiting the time of anesthesia. One approach to prolong analgesia is to entrap local anesthetic agents in nanostructured carriers (e.g., liposomes). Here, we report that using an ammonium sulphate gradient was the best strategy to improve the encapsulation (62.6%) of dibucaine (DBC) into liposomes. Light scattering and nanotracking analyses were used to characterize vesicle properties, such as, size, polydispersity, zeta potentials, and number. In vitro kinetic experiments revealed the sustained release of DBC (50% in 7 h) from the liposomes. In addition, in vitro (3T3 cells in culture) and in vivo (zebrafish) toxicity assays revealed that ionic-gradient liposomes were able to reduce DBC cyto/cardiotoxicity and morphological changes in zebrafish larvae. Moreover, the anesthesia time attained after infiltrative administration in mice was longer with encapsulated DBC (27 h) than that with free DBC (11 h), at 320 μM (0.012%), confirming it as a promising long-acting liposome formulation for parenteral drug administration of DBC. 相似文献
76.
Nandita Perumal Daniel E. Roth Johnna Perdrizet Aluísio J. D. Barros Iná S. Santos Alicia Matijasevich Diego G. Bassani 《Emerging themes in epidemiology》2018,15(1):3
Background
Postmenstrual and/or gestational age-corrected age (CA) is required to apply child growth standards to children born preterm (< 37 weeks gestational age). Yet, CA is rarely used in epidemiologic studies in low- and middle-income countries (LMICs), which may bias population estimates of childhood undernutrition. To evaluate the effect of accounting for GA in the application of growth standards, we used GA-specific standards at birth (INTERGROWTH-21st newborn size standards) in conjunction with CA for preterm-born children in the application of World Health Organization Child Growth Standards postnatally (referred to as ‘CA’ strategy) versus postnatal age for all children, to estimate mean length-for-age (LAZ) and weight-for-age (WAZ) z scores at 0, 3, 12, 24, and 48-months of age in the 2004 Pelotas (Brazil) Birth Cohort.Results
At birth (n = 4066), mean LAZ was higher and the prevalence of stunting (LAZ < ?2) was lower using CA versus postnatal age (mean ± SD): ? 0.36 ± 1.19 versus ? 0.67 ± 1.32; and 8.3 versus 11.6%, respectively. Odds ratio (OR) and population attributable risk (PAR) of stunting due to preterm birth were attenuated and changed inferences using CA versus postnatal age at birth [OR, 95% confidence interval (CI): 1.32 (95% CI 0.95, 1.82) vs 14.7 (95% CI 11.7, 18.4); PAR 3.1 vs 42.9%]; differences in inferences persisted at 3-months. At 12, 24, and 48-months, preterm birth was associated with stunting, but ORs/PARs remained attenuated using CA compared to postnatal age. Findings were similar for weight-for-age z scores.Conclusions
Population-based epidemiologic studies in LMICs in which GA is unused or unavailable may overestimate the prevalence of early childhood undernutrition and inflate the fraction of undernutrition attributable to preterm birth.77.
Healthcare systems are increasingly recognised as complex, in which a range of non-linear and emergent behaviours occur. China’s healthcare system is no exception. The hugeness of China, and the variation in conditions in different jurisdictions present very substantial challenges to reformers, and militate against adopting one-size-fits-all policy solutions. As a consequence, approaches to change management in China have frequently emphasised the importance of sub-national experimentation, innovation, and learning. Multiple mechanisms exist within the government structure to allow and encourage flexible implementation of policies, and tailoring of reforms to context. These limit the risk of large-scale policy failures and play a role in exploring new reform directions and potentially systemically-useful practices. They have helped in managing the huge transition that China has undergone from the 1970s onwards. China has historically made use of a number of mechanisms to encourage learning from innovative and emergent policy practices. Policy evaluation is increasingly becoming a tool used to probe emergent practices and inform iterative policy making/refining. This paper examines the case of a central policy research institute whose mandate includes evaluating reforms and providing feedback to the health ministry. Evaluation approaches being used are evolving as Chinese research agencies become increasingly professionalised, and in response to the increasing complexity of reforms. The paper argues that learning from widespread innovation and experimentation is challenging, but necessary for stewardship of large, and rapidly-changing systems. 相似文献
78.
Ho Young Kim Ju Young Kim Hwa Yeon Park Ji Hye Jun Hye Yeon Koo In Young Cho Jinah Han Yuliya Pak Hyun Jung Baek Ju Yeon Lee Sung Hee Chang Jung Hun Lee Ji Soo Choe Sun-kyung Yang Kyung Chul Kim Jeong Ha Park Seul Ki Paik 《Globalization and health》2018,14(1):120
Background
With the significant growth of migration and expatriation, facilitated by increased global mobility, the number of Koreans living abroad as of 2016 is approximately 7.4 million (15% of the Korean population). Healthcare utilization or health problems, especially among expatriates in developing countries, have not been well researched despite the various health risks these individuals are exposed to. Consequently, we identified the health utilization patterns and healthcare needs among Korean expatriates in Vietnam, Cambodia, and Uzbekistan.Methods
This cross-sectional survey examined 429 Korean expatriates living in Vietnam (n?=?208), Cambodia (n?=?60), and Uzbekistan (n?=?161) who had access to the Internet and were living abroad for at least 6?months. A 67-item questionnaire was used, and feedback was received via an online survey program. Stepwise logistic regression analyses were performed to evaluate factors associated with unmet healthcare needs and preferences of certain type of telemedicine.Results
We found that 45.5% (195/429) of respondents had used medical services in their country of stay. Among those who visited health institutions >?3 times, the most popular choice was general hospitals (39.4%, 15/38); however, they initially visited Korean doctors’ or local doctors’ offices. The most essential criteria for healthcare service facilities was a “skilled professional” (39.3%, 169/429), 42% wanted a health program for chronic disease management, and 30% wanted specialized internal medicine. A substantial number wanted to access telemedicine services and were willing to pay for this service. They were particularly interested in experts’ second opinion (61.5%, 264/429) and quick, 24-h medical consultations (60.8%, 261/429). Having unmet healthcare needs and being younger was strongly associated with all types of telemedicine networks.Conclusions
Nearly half of the expatriates in developing countries had unmet healthcare needs. Telemedicine is one potential solution to meet these needs, especially in developing countries.79.
Background
Ukraine, one of the largest states formed on the rubble of the Soviet Union, is widely perceived as a country that has lost its opportunities. Being devastated by corruption, it shows incapable to modernize and enter the economic path of sustainable growth. Similarly in the health care system no deeper reform efforts have been taken in the entire post-soviet period, leaving the system in bonds of ineffective solutions taken out of the Soviet era.Main body
The recent geopolitical and economic crisis seem to favor the introduction of radical solutions that might lead to a rapid change in the organizational paradigm of the economic system, as well as in health care in Ukraine. In this paper we aim to highlight the key features of the ongoing health reform in Ukraine, identify basic challenges for it, and assess rationality and feasibility of the reform. We found that the projected scope and schedule of changes in the Ukrainian health system give promising prognosis regarding its final effect.Conclusions
The final success of health reform in Ukraine is dependent on a number of factors, including the financial foundation arising of economic stability of the country, balance assurance between public and private spending for health and ability to eliminate the long-lasting practices, particularly when they are connected with activities of lobbying groups occupying particular positions in the health system. A consequence of actions taken by the political decision-makers in the longer perspective are also to highly determine the reform’s chances for success.80.