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   4996篇
  免费   367篇
  国内免费   35篇
耳鼻咽喉   83篇
儿科学   124篇
妇产科学   92篇
基础医学   729篇
口腔科学   500篇
临床医学   505篇
内科学   991篇
皮肤病学   136篇
神经病学   447篇
特种医学   44篇
外科学   406篇
综合类   28篇
预防医学   569篇
眼科学   100篇
药学   417篇
中国医学   37篇
肿瘤学   190篇
  2024年   8篇
  2023年   68篇
  2022年   120篇
  2021年   281篇
  2020年   170篇
  2019年   212篇
  2018年   266篇
  2017年   161篇
  2016年   207篇
  2015年   224篇
  2014年   299篇
  2013年   291篇
  2012年   483篇
  2011年   547篇
  2010年   268篇
  2009年   200篇
  2008年   289篇
  2007年   340篇
  2006年   225篇
  2005年   200篇
  2004年   159篇
  2003年   107篇
  2002年   107篇
  2001年   23篇
  2000年   23篇
  1999年   13篇
  1998年   13篇
  1997年   5篇
  1996年   12篇
  1995年   5篇
  1994年   7篇
  1993年   4篇
  1992年   8篇
  1991年   3篇
  1990年   6篇
  1989年   3篇
  1988年   2篇
  1986年   5篇
  1985年   2篇
  1984年   4篇
  1982年   2篇
  1981年   3篇
  1980年   4篇
  1979年   4篇
  1977年   2篇
  1973年   2篇
  1969年   1篇
  1968年   3篇
  1967年   2篇
  1966年   1篇
排序方式: 共有5398条查询结果,搜索用时 484 毫秒
61.
Objective: This study aimed to investigate a flaxseed diet during different developmental periods, and its effect on the blood pressure of rats submitted to stress.

Methods: Fifty-six male rats (F1), born from 14 rats (F0), were divided into seven groups (n?=?8): flaxseed group (FG); flaxseed group gestation and lactation (FG-GL); flaxseed group weaning (FG-W); flaxseed group weaning and stress (FG-WS); flaxseed group stress (FG-S); flaxseed group gestation lactation and weaning (FG-GLW), and control Group (CG). Stress protocol was undertaken for 1 month. Blood pressure was analysed before and after the stress protocol. The left adrenal glands and serum corticosterone levels were analysed.

Results: Systolic blood pressure before stress was lower in all groups with flaxseed diet compared with the CG (p?=?.00001). After stress, CG showed higher blood pressure compared with FG, FG-GL, and FG-GLW (p?=?.004). The levels of corticosterone were lower in the FG between all groups (p?p?Conclusions: Results suggest a possible factor from a flaxseed diet against the effects of stress on a blood pressure in all periods of life but especially in the gestation and lactation periods.  相似文献   
62.
63.
BackgroundChromoblastomycosis is a skin infection caused by dematiaceous fungi that take the form of muriform cells in the tissue. It mainly manifests as verrucous plaques on the lower limbs of rural workers in tropical countries.ObjectivesThe primary objective of this review is to evaluate the accuracy of diagnostic methods for the identification of chromoblastomycosis, considering the histopathological examination as the reference test.MethodsMEDLINE, LILACS and Scielo databases were consulted using the terms “chromoblastomycosis” AND “diagnosis”. The eligibility criteria were: studies that evaluated the accuracy of tests for the diagnosis of chromoblastomycosis. Eleven studies were selected. Statistical analysis included the calculation of sensitivity and specificity of the diagnostic methods.ResultsConsidering the histopathological examination as the reference test, the culture showed a sensitivity (S) of 37.5% - 90.9% and a specificity (Sp) of 100%; while direct mycological examination showed S = 50% - 91.6% and Sp of 100% . Considering the culture as the reference test, the serology (precipitation techniques) showed S of 36% - 99%; and Sp of 80% - 100%; while the intradermal test showed S of 83.3% - 100% and Sp of 99.4% - 100%.Study limitationsThe small number of studies and very discrepant sensitivity results among them do not allow the calculation of summary measures through a meta-analysis.ConclusionsDirect mycological examination, culture, intradermal test and serology show sensitivity and specificity values ??for the diagnosis of chromoblastomycosis with no significant difference between the studies.  相似文献   
64.
Multiple locus variable number tandem repeats (VNTRs) analysis (MLVA) has become a reliable tool, able to establish genetic relationships for epidemiological surveillance and molecular subtyping of pathogens such as verotoxigenic Escherichia coli (VTEC). This emerging pathogen whose primary reservoir is the cattle causes severe disease in humans, such as hemorrhagic colitis and hemolytic uremic syndrome. With the aim of comparing a recently proposed MLVA assay with that used routinely in our laboratory, we analyzed a set of VTEC isolates (n = 72) obtained from meat using both assays. All samples could be typed by the new MLVA assay, and an increase in the number of distinct profiles (31–43) was observed. However, intraserotype resolution was not significantly enhanced; thus, the incorporation of more VNTR loci is still needed to achieve a greater discrimination among non-O157:H7 serotypes.  相似文献   
65.
Parasitology Research - Phthalimide, 1,3-thiazole, and thiazolidinone cores are considered privileged scaffolds and represent an attractive starting point to design new bioactive compounds for...  相似文献   
66.
We evaluated the possible mechanisms underlying the oxidative stress induced by ethanol withdrawal. With this purpose, we verified the role of AT1 receptors in such response. Male Wistar rats were treated with ethanol 3%–9% (vol./vol.) for 21 days. Ethanol withdrawal was induced by abrupt discontinuation of the treatment. Experiments were performed 48 hours after ethanol discontinuation. Increased plasma levels of angiotensin II were detected after ethanol withdrawal. Losartan (10 mg/kg; p.o. gavage), a selective AT1 receptor antagonist, impeded the increase in blood pressure induced by ethanol withdrawal. Increased lipoperoxidation and superoxide anion (O2?) levels were detected in aortas after ethanol withdrawal, and losartan prevented these responses. Decreased hydrogen peroxide and nitrate/nitrite concentration were detected in aortas after ethanol withdrawal, and losartan prevented these effects. Nitrotyrosine immunostaining in the rat aorta was increased after ethanol withdrawal, and AT1 blockade impeded this response. Increased expression of PKCδ and p47phox was detected after ethanol withdrawal, and treatment with losartan prevented these responses. Our study provides novel evidence that ethanol withdrawal increases vascular oxidative stress and blood pressure through AT1-dependent mechanisms. These findings highlight the importance of angiotensin II in ethanol withdrawal–induced increase in blood pressure and vascular oxidative damage.  相似文献   
67.
68.
The past 2 decades have seen a considerable global increase in cardiovascular disease, with hypertension remaining by far the most common. More than one-third of adults in Africa are hypertensive; as in the urban populations of most developing countries. Being a condition that occurs with relatively few symptoms, hypertension remains underdetected in many countries; especially in developing countries where routine screening at any point of health care is grossly underutilized. Because hypertension is directly related to cardiovascular disease, this has led to hypertension being the leading cause of adverse cardiovascular outcomes, as a result of patients living, often unknowingly, with uncontrolled hypertension for prolonged periods of time. In Africa, hypertension is the leading cause of heart failure; whereas at global levels, hypertension is responsible for more than half of deaths from stroke, just less than half of deaths from coronary artery disease, and for more than one-tenth of all global deaths. In this review, we discuss the escalating occurrence of hypertension in developing countries, before exploring the strengths and weaknesses of different measures to control hypertension, and the challenges of adopting these measures in developing countries. On a broad level, these include steps to curb the ripple effect of urbanization on the health and disease profile of developing societies, and suggestions to improve loopholes in various aspects of health care delivery that affect surveillance and management of hypertension. Furthermore, we consider how the industrial sectors' contributions toward the burden of hypertension can also be the source of the solution.  相似文献   
69.
ObjectiveInfant sleep problems can affect the child's health. Maternal characteristics have been associated with the quality of infant sleep, but few studies have investigated the impact of intrauterine conditions. The aim of the study was to evaluate the association between adverse intrauterine environments (maternal smoking, hypertension, diabetes, and intrauterine growth restriction) and extrauterine factors on infant sleep in the first 6 months of life.MethodsProspective cohort study, including singleton and at-term infants. Mothers were interviewed after delivery and at 30 days, 3 months, and 6 months of life. Socioeconomic, breastfeeding, and sleep data were self-reported by mothers using semi-structured interviews. Maternal stress (Perceived Stress Scale) and postpartum depression symptoms (Edinburgh Postpartum Depression Scale) were assessed.ResultsThere was no statistically significant association between intrauterine environments and the sleep of infants of the 359 mother–child dyads investigated. Total infant sleep time decreased from approximately 13–11 h from 30 days to 6 months of age (p < 0.001) and the longest period of uninterrupted sleep increased from approximately 4–6 h during the same period (p < 0.001). Breastfed infants slept longer in 24-h periods in the first month, but they woke up more often throughout the night when compared to infants receiving formula. Mothers with depressive symptoms reported increased sleep latency time.ConclusionsAdverse intrauterine environments did not significantly affect sleep measures in the first 6 months of life. Maternal characteristics and practices, however, were associated with infant sleep, suggesting that environmental factors significantly contribute to sleep quality early in life.  相似文献   
70.
Journal of Autism and Developmental Disorders - Autism spectrum disorders (ASD) are associated with high services use, but European data on costs are scarce. Utilisation and annual costs of 385...  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