全文获取类型
收费全文 | 81610篇 |
免费 | 9597篇 |
国内免费 | 399篇 |
专业分类
耳鼻咽喉 | 696篇 |
儿科学 | 1991篇 |
妇产科学 | 3131篇 |
基础医学 | 7973篇 |
口腔科学 | 1662篇 |
临床医学 | 21372篇 |
内科学 | 16389篇 |
皮肤病学 | 864篇 |
神经病学 | 5582篇 |
特种医学 | 2092篇 |
外国民族医学 | 2篇 |
外科学 | 10699篇 |
综合类 | 1045篇 |
现状与发展 | 1篇 |
一般理论 | 103篇 |
预防医学 | 6865篇 |
眼科学 | 1868篇 |
药学 | 4481篇 |
中国医学 | 140篇 |
肿瘤学 | 4650篇 |
出版年
2023年 | 1026篇 |
2022年 | 465篇 |
2021年 | 1373篇 |
2020年 | 1321篇 |
2019年 | 1201篇 |
2018年 | 2302篇 |
2017年 | 2164篇 |
2016年 | 2353篇 |
2015年 | 2583篇 |
2014年 | 3255篇 |
2013年 | 4520篇 |
2012年 | 4179篇 |
2011年 | 4776篇 |
2010年 | 3368篇 |
2009年 | 3493篇 |
2008年 | 4635篇 |
2007年 | 4718篇 |
2006年 | 4553篇 |
2005年 | 4548篇 |
2004年 | 4241篇 |
2003年 | 3801篇 |
2002年 | 3712篇 |
2001年 | 1194篇 |
2000年 | 893篇 |
1999年 | 1135篇 |
1998年 | 1311篇 |
1997年 | 1293篇 |
1996年 | 1124篇 |
1995年 | 1049篇 |
1994年 | 871篇 |
1993年 | 762篇 |
1992年 | 779篇 |
1991年 | 743篇 |
1990年 | 650篇 |
1989年 | 617篇 |
1988年 | 532篇 |
1987年 | 502篇 |
1986年 | 478篇 |
1985年 | 560篇 |
1984年 | 533篇 |
1983年 | 490篇 |
1982年 | 609篇 |
1981年 | 531篇 |
1980年 | 535篇 |
1979年 | 376篇 |
1978年 | 378篇 |
1977年 | 385篇 |
1976年 | 326篇 |
1975年 | 324篇 |
1974年 | 276篇 |
排序方式: 共有10000条查询结果,搜索用时 406 毫秒
991.
Margrét Gudnadottir RN MS Christine Ceci RN PhD Marit Kirkevold RN EdD Kristín Björnsdóttir RN EdD 《Health & social care in the community》2021,29(4):1091-1099
Studies of families caring for persons with dementia living at home often reflect feelings of being forgotten and abandoned by the authorities to shoulder the responsibility for care-giving. This has increased interest in how formal services can better support these families. This article analyses how health and social care professionals envision the needs of families of persons with dementia living in the community. It also describes the contributions of the formal care system to these families. The study design was qualitative. It involved interviews with professionals (N = 20), field observations from the settings where they worked, and public documents addressing care-giving for people with dementia. Data were analysed using the framework method. The findings reflected how those providing services to persons experiencing cognitive changes mainly understood the services as specialised. They focused on the diagnosis and treatment of the individual with dementia. They considered other aspects of care, such as attending to practical issues of daily life, to be a private matter, for which the family was responsible. In later stages of dementia, specialised day programs become available, offering rehabilitation to motivate positive daily living—for both the person experiencing dementia and family-centred supporters. Professionals in the field described primary care, community-based healthcare and home care services as poorly equipped to support these families. Participants acknowledged that families were often under a lot of stress and might need more support earlier in the illness. However, they saw themselves as powerless. Towards the end of the data collection, services were being re-designed to emphasise the role of primary care. In light of its holistic and family-centred approach, primary care may be well placed to integrate relational understanding of living with dementia and specialised knowledge of dementia treatment. 相似文献
992.
Hussan Zeb RN BSN MSPH Ahtisham Younas RN BSN MN Israr Ahmed RN BSN Anwar Ali MBBS FCPS MRCP 《Health & social care in the community》2021,29(5):e174-e183
Self-care enables patients in improving quality of life and reducing hospital admissions. Research explored the experiences of patients about breathlessness, sleep problems and complication management in chronic obstructive pulmonary disease (COPD). However, the self-care experiences and the role of the family in self-care are underexplored. This study aimed to understand the self-care experiences of patients with COPD and explore the role of the family in self-care. An interpretive phenomenological inquiry was used, and 13 patients were interviewed in 2019 from two hospitals in Pakistan. The inclusion criteria were patients above 30 years of age at any stage of COPD, who received a confirmed diagnosis of COPD and were receiving the treatment, and engaged in self-care at their homes or communities. The interviews lasted for 35–60 min. Ricoeur's interpretation theory was used for data analysis comprising steps explanation, naive understanding and in-depth understanding. Self-care emerged as a complex individual and familial endeavour affected by personal, social and economic factors. Poverty was one of the core determinants of self-care. Patients emphasised the spiritual, cultural and traditional approaches to self-care. Future research is warranted to develop better understanding of spiritual and cultural self-care and how these dimensions of self-care affect patients’ self-care behaviours. 相似文献
993.
The cardiovascular and respiratory effect of whole cobra venom and a purified cobra venom fraction were compared in dogs and cats. Both the crude venom and the fraction affected the respiration of dogs markedly and that of cats to a lesser degree. At lethal doses respiratory failure occurred. Cobra venom greatly lowered the blood pressure and decreased the heart rate of dogs and cats. Lethal doses of the fraction produced minimal hypotension and minimal bradycardia in dogs; sublethal and lethal doses produced a similar bradycardiac response in cats. 相似文献
994.
995.
STUDY OBJECTIVES: Pharmacologic enhancement of daytime sleep may help sustain optimal cognitive performance. At effective doses, zolpidem induces sleep but also impairs performance. Combining melatonin with low-dose zolpidem may promote daytime sleep without exacerbating performance impairments seen with high-dose zolpidem alone. DESIGN AND METHODS: Following an 8-hour undisturbed nighttime sleep period, 80 subjects (50 men, 30 women) were administered oral zolpidem 0, 5, 10, or 20 mg at 10:00 am (n = 20 per group) and then oral melatonin 0 or 5 mg at 10:30 am (thus, n = 10 per drug combination) in a double-blind randomized fashion. Subjects napped from 10:00 am to 11:30 am, at which time they were awakened and cognitive tests administered (Restricted Reminding, Paired-Associates, and Psychomotor Vigilance). A second nap ensued from 12:45 pm to 4:00 pm, followed immediately by further testing. RESULTS: Melatonin 5 mg plus zolpidem 0 mg enhanced daytime sleep (P < .05) with no memory or performance impairment (P > .05). Zolpidem 20 mg plus melatonin 0 mg also enhanced daytime sleep (albeit nonsignificantly), but memory and vigilance were impaired (P < .05). Melatonin's sleep-promoting effects were not evident until the second nap. CONCLUSIONS: No advantages to administering melatonin plus zolpidem "cocktails" were evident. Unlike zolpidem, melatonin 5 mg alone improved daytime sleep without impairing memory and vigilance. Functional coupling of sleep-inducing and memory-impairing effects may be specific to benzodiazepine-receptor agonists such as zolpidem, suggesting potential advantages to using melatonin in the operational environment. That melatonin's sleep-promoting effects were delayed for several hours presents a practical consideration that may limit melatonin's usefulness when daytime sleep periods cannot be reliably anticipated or planned in advance. 相似文献
996.
The incidence of abnormal morphology and nucleocytoplasmic ratios in 2-, 3- and 5-day human pre-embryos 总被引:3,自引:7,他引:3
N J Winston P R Braude S J Pickering M A George A Cant J Currie M H Johnson 《Human reproduction (Oxford, England)》1991,6(1):17-24
Human cleaving pre-embryos at 2 and 3 days and cavitated pre-embryos at 5 days post-insemination have been examined for cell number and the incidence of mononucleated cells. At least 60% of polynucleate or anucleate cells have been detected at all these stages and regardless of morphological grading at day 2. It is concluded that even by the time at which pre-embryo replacement would occur therapeutically, the majority of pre-embryos are unlikely to have full developmental potential. The possible origins of the abnormalities of nucleocytoplasmic ratios are discussed. 相似文献
997.
The Perception of Procedures Questionnaire: Psychometric Properties of a Brief Parent Report Measure of Procedural Distress 总被引:1,自引:3,他引:1
Kazak Anne E.; Penati Biancamaria; Waibel Mary Katherine; Blackall George F. 《Journal of pediatric psychology》1996,21(2):195-207
Reported the reliability and validity of the Perception of ProceduresQuestionnaire (PPQ), a 19-item parent-report measure developedto assess child and parent distress related to lumbar puncturesand bone marrow aspirates in the diagnosis and treatment ofchildhood cancer. PPQ data from 140 mothers and 96 fathers ofchildren and adolescents with leukemia in a first remissionwere analyzed separately. Factor analyses yielded five factorsfor mothers and fathers: Parent Satisfaction; Child Distress:During; Child Distress: Before; Parent Distress; and ParentInvolvement. Internal consistency (Cronbach's alpha) was highfor the total score and the five factor scores as were interraterreliabilities between mothers and fathers. Validity was determinedusing the Parenting Stress Index-Short Form, the Pediatric OncologyQuality of Life Scale, and parent and nurse ratings during procedures.Factors 2 and 3, assessing child distress, show strong associationswith the validation measures and support the distinction betweendistress before and during procedures. This developing scaleis recommended for use in the assessment and evaluation of childand parent procedure-related distress in pediatric oncology. 相似文献
998.
The development of statistical methodologies for quantitative trait locus (QTL) mapping in polyploids is complicated by complex polysomic inheritance. In this article, we propose a statistical method for mapping QTL in tetraploids undergoing bivalent formation at meiosis by using single-dose restriction fragments. Our method is based on a unified framework, one that uses chromosome bivalent pairing configuration and gametic recombination to discern different mechanisms of gamete formation. Our bivalent polyploid model can not only provide a simultaneous estimation of the linkage and chromosome pairing configuration-a cytological parameter of evolutionary and systematic interest-but also enhances the precision of estimating QTL effects and position by correctly characterizing gene segregation during polyploid meiosis. By using our method and a linkage map constructed in a previous study, we successfully identify several QTL affecting winter hardiness in bivalent tetraploid alfalfa. Moreover, our results reveal significant preferential chromosome pairing at meiosis in an F1 hybrid population, which indicates the importance of reassessing the traditional view of random chromosome segregation in alfalfa. 相似文献
999.
The effects of 4-aminopyridine (4-AP) were studied on isolated papillary muscles from the heart of reserpinized rabbits (at 37°C). The preparations were paced to contract at 0.67 Hz under isometric conditions and the muscle length was adjusted to 95 % of the length for optimum force production. Simultaneous recordings of isometric force and membrane potentials were performed. 4-AP (50 μM) increased peak force by approximately 20% of the control and prolonged the action potential by 20%. Higher concentrations of 4-AP (800 μ.M) resulted in further increments of force and action potential duration (60 and 70% of controls, respectively). Prolongation of the action potential and potentiation of the isometric force was still present one hour after withdrawal of the drug from the perfusate. The results are consistent with the view that 4-AP prolongs the action potential by inhibiting the late repolarizing potassium current. It is suggested that the calcium uptake by the ventricular cell during the prolonged action potential is increased and that this leads to the positive inotropic effect. 相似文献
1000.