全文获取类型
收费全文 | 7184篇 |
免费 | 416篇 |
国内免费 | 30篇 |
专业分类
耳鼻咽喉 | 73篇 |
儿科学 | 153篇 |
妇产科学 | 173篇 |
基础医学 | 1219篇 |
口腔科学 | 748篇 |
临床医学 | 445篇 |
内科学 | 1323篇 |
皮肤病学 | 155篇 |
神经病学 | 529篇 |
特种医学 | 550篇 |
外科学 | 576篇 |
综合类 | 61篇 |
一般理论 | 1篇 |
预防医学 | 693篇 |
眼科学 | 63篇 |
药学 | 520篇 |
1篇 | |
中国医学 | 57篇 |
肿瘤学 | 290篇 |
出版年
2024年 | 7篇 |
2023年 | 55篇 |
2022年 | 134篇 |
2021年 | 182篇 |
2020年 | 128篇 |
2019年 | 178篇 |
2018年 | 238篇 |
2017年 | 167篇 |
2016年 | 188篇 |
2015年 | 210篇 |
2014年 | 318篇 |
2013年 | 349篇 |
2012年 | 489篇 |
2011年 | 566篇 |
2010年 | 298篇 |
2009年 | 254篇 |
2008年 | 393篇 |
2007年 | 427篇 |
2006年 | 315篇 |
2005年 | 329篇 |
2004年 | 258篇 |
2003年 | 235篇 |
2002年 | 172篇 |
2001年 | 133篇 |
2000年 | 124篇 |
1999年 | 124篇 |
1998年 | 120篇 |
1997年 | 110篇 |
1996年 | 93篇 |
1995年 | 78篇 |
1994年 | 53篇 |
1993年 | 72篇 |
1992年 | 56篇 |
1991年 | 46篇 |
1990年 | 61篇 |
1989年 | 73篇 |
1988年 | 64篇 |
1987年 | 55篇 |
1986年 | 62篇 |
1985年 | 79篇 |
1984年 | 42篇 |
1983年 | 32篇 |
1982年 | 36篇 |
1981年 | 36篇 |
1980年 | 41篇 |
1979年 | 16篇 |
1978年 | 18篇 |
1977年 | 27篇 |
1976年 | 23篇 |
1975年 | 23篇 |
排序方式: 共有7630条查询结果,搜索用时 46 毫秒
51.
Objective: To identify factors that influence a woman's decision to breast-feed.
Methodology: Five hundred and fifty-six women were recruited from the maternity wards of two Perth hospitals. Data were collected from a self-administered questionnaire completed by participants prior to discharge. Logistic regression analysis was used to determine factors influencing the initiation of breast-feeding.
Results: At discharge from hospital 83.8% of women were breast-feeding, including 6% who were giving complementary formula feeds. After controlling for potentially confounding demographic and biomedical factors, the father's reported preference for breast-feeding was found to be the most important factor influencing a woman's decision to breast-feed (OR 10.18).
Conclusion: Fathers participate in and influence the choice of infant feeding method and should be included in breast-feeding discussions. 相似文献
Methodology: Five hundred and fifty-six women were recruited from the maternity wards of two Perth hospitals. Data were collected from a self-administered questionnaire completed by participants prior to discharge. Logistic regression analysis was used to determine factors influencing the initiation of breast-feeding.
Results: At discharge from hospital 83.8% of women were breast-feeding, including 6% who were giving complementary formula feeds. After controlling for potentially confounding demographic and biomedical factors, the father's reported preference for breast-feeding was found to be the most important factor influencing a woman's decision to breast-feed (OR 10.18).
Conclusion: Fathers participate in and influence the choice of infant feeding method and should be included in breast-feeding discussions. 相似文献
52.
OBJECTIVE: Most neonatologists include an apnea-free period in the criteria for the discharge of preterm infants. However, the length of time one should wait after the cessation of apnea before sending an infant home without a monitor is debated. We undertook this study in an attempt to define a minimal and safe observation period between the time of the last apnea episode and discharge. METHODS: We reasoned that in infants with idiopathic apnea of prematurity, the intervals between days on which apnea occurs gradually increase until some point at which clinically significant apnea ceases. Therefore, knowledge about the intervals between days on which apnea occurred just before the last apnea would provide a reasonable estimate of the minimal safe observation interval between the last apnea and discharge. We reviewed the charts of 266 infants born in 1993 and 1994 at =32 weeks' gestational age or weighing =1500 g at birth from two institutions to determine the intervals between the day on which the last apnea occurred and the previous two days on which apnea occurred. One hundred seventy-five infants were excluded because they never experienced apnea, or data about the last apnea was missing, or they were on xanthines during the period encompassing the last 3 apnea days, or they weighed <1500 g or were <34 weeks' postmenstrual age at the time of the last apnea. Of the 91 remaining infants, gestational age at birth, birth weight, 1- and 5-minute Apgar scores, and discharge weight were not different between the two institutions. For each infant we determined the longest of the intervals between the 2 days on which apnea occurred previous to the day of the last apnea (MAXINT for maximum interval). The infants were then ordered by MAXINT and, starting at the longest MAXINT, the medical records of each infant were carefully examined for other conditions known to be associated with apnea (eg, recovering from anesthesia, sepsis, chronic lung disease, and so forth). The minimal safe observation period was then defined as the longest MAXINT in which there was at least 1 infant with no other explanation for the apnea other than prematurity. RESULTS: The median duration of the intervals between the 2 days on which apnea occurred previous to the day on which the last apnea occurred were 3. 0 and 2.0 days and the median duration of the MAXINT was 4.0 days. On careful examination of the charts, it was determined that each of 13 infants with a MAXINT preceding the day on which the last apnea occurred of greater than 8 days had some other condition that might result in apnea, including residual lung disease, sepsis, surgery, and so forth. In contrast, among the group of infants with a MAXINT of =8 days, at least 1 infant at each MAXINT (eg, 1 to 8) had significant apnea with no other explanation other than prematurity. CONCLUSIONS: We conclude that otherwise healthy preterm infants continue to have apneas separated by as many as 8 days before the last apnea before discharge. Conversely, infants with longer apnea intervals often have identifiable risk factors other than apnea of prematurity. 相似文献
53.
54.
Carlos Alberto Temes de Quadros Cesar Gomes Victora Juvenal Soares Dias da Costa 《Pan American journal of public health》2004,16(4):223-232
OBJECTIVE: To determine the coverage and focus of cervical cancer screening (Pap smears) in a population-based sample in Brazil. METHODS: Cross-sectional cluster survey covering 1730 women aged 20 years or older with a history of sexual activity. Information was collected on social, demographic and behavioral variables, knowledge of and use of the Pap test. RESULTS: Of women aged 25-59 years, who are the target population of the national cervical cancer screening program, 78.7% had had at least one Pap test in their lifetime, and 68.8% had had a Pap test in the last 3 years. Statistics for focus of the program showed that of the 637 women who reported having a Pap test in the last year, only 20.6% actually required one. The remainder were either outside the age range or had had another test less than 30 months previously. Prevalence of not having been tested in the previous 3 years was highest among black (41.7%) and low-income women (64.3%), and among those at greatest risk for cervical cancer (62.3% for women with three or more risk factors). Focus was inversely related to socioeconomic status. CONCLUSION: Coverage rates were similar to those reported in other national studies, but this is the first report to examine the focus of the national program. We show that 8 of every 10 Pap tests were not necessary. Coverage levels remain unacceptably low among women of low socioeconomic status and those at greatest risk for cervical cancer. 相似文献
55.
56.
M Sala J Perez P Soloff S Ucelli di Nemi E Caverzasi J C Soares P Brambilla 《European neuropsychopharmacology》2004,14(5):393-405
The hippocampus plays a main role in regulating stress response in humans, but is itself highly sensitive to neurotoxic effects of repeated stressful episodes. Hippocampal atrophy related to experimental stress has been reported in laboratory studies in animals. Several controlled brain imaging studies have also shown hippocampal abnormalities in psychiatric disorders, including posttraumatic stress disorder (PTSD), major depressive disorder (MDD), and borderline personality disorder (BPD). This paper reviews the physiological role of the hippocampus in stress circuitry and the effects of stress on cognitive functions mediated by the hippocampus. We also review brain imaging studies investigating hippocampus in PTSD, MDD, and BPD. This literature suggests that individuals with PTSD, MDD, and BPD may suffer hippocampal atrophy as a result of stressors associated with these disorders. Prospective, longitudinal studies will be needed in high-risk offspring and first-episode subjects to explore the relationship between stress and hippocampal atrophy in these neuropsychiatric illnesses. 相似文献
57.
Ana Luísa Soares de Miranda Bruno Cesar Antunes Joo Carlos Minozzo Sabrina de Almeida Lima Ana Flvia Machado Botelho Marco Túlio Gomes Campos Carlos Delfin Chvez-Olrtegui Benito Soto-Blanco 《Toxins》2022,14(5)
Bites of brown spiders (Loxosceles spp.) are responsible for dermonecrotic lesions and potentially systemic envenoming that can lead to death. The only effective therapy is the use of the antivenom, usually produced in horses. However, little is known about the consequences of the systematic use of the Loxosceles venom and adjuvants and of the bleedings on antivenom-producing horses. Thus, the aim of this study was to evaluate the clinical changes in horses in their first immunization protocol for Loxosceles antivenom production. Eleven healthy horses, never immunized, were evaluated in three different periods: T0 (before immunization); T1 (after their first venom immunization); and T2 (after their first bleeding). Horses were clinically evaluated, sampled for blood, and underwent electrocardiographic (ECG) recordings. Several suppurated subcutaneous abscesses occurred due to the use of Freund’s adjuvants and thrombophlebitis due to systematic venipunctures for the bleeding procedures. ECG showed arrhythmias in few horses in T2, such as an increase in T and R waves. In summary, the immunization protocol impacted on horses’ health, especially after bleeding for antivenom procurement. 相似文献
58.
Alexandre de Matos Soeiro Bruno Biselli Tatiana C.A.T. Leal Aline Siqueira Bossa Maria Cristina Csar Srgio Jallad Priscila Gherardi Goldstein Patrícia Oliveira Guimares Carlos Vicente Serrano Jr Cesar Higa Nomura Dbora Nakamura Carlos Eduardo Rochitte Paulo Rogrio Soares Múcio Tavares de Oliveira Jr. 《Arquivos brasileiros de cardiologia》2022,118(5):894
BackgroundCoronary tomography angiography (CTA) has been mainly used for chest pain evaluation in low-risk patients, and few data exist regarding patients at intermediate risk.ObjectiveTo evaluate the performance of serial measures of sensitive troponin and CTA in intermediate-risk patients.MethodsA total of 100 patients with chest pain, TIMI risk scores of 3 or 4, and negative troponin were prospectively included. All patients underwent CTA and those with coronary stenosis ≥ 50% were referred to invasive coronary angiography. Patients with coronary lesions <50% were discharged and contacted 30 days later by a telephone call to assess clinical outcomes. Outcomes were hospitalization, death, and myocardial infarction at 30 days. The comparison between methods was performed by Kappa agreement test. The performance of troponin measures and CTA for detecting significant coronary lesions and clinical outcomes was calculated. Results were considered statistically significant when p < 0.05.ResultsCoronary stenosis ≥ 50% on CTA was found in 38% of patients and significant coronary lesions on coronary angiography were found in 31 patients. Two clinical events were observed. Kappa agreement analysis showed low agreement between troponin measures and CTA in the detection of significant coronary lesions (kappa = 0.022, p = 0.78). The performance of CTA for detecting significant coronary lesions on coronary angiography or for predicting clinical events at 30 days was better than sensitive troponin measures (accuracy of 91% versus 60%).ConclusionCTA performed better than sensitive troponin measures in the detection of significant coronary disease in patients with chest pain and intermediate risk for cardiovascular events. 相似文献
59.
The placenta forms a selective barrier that is able to transport nutrients that are of critical use to the fetus. Delivery of essential fatty acids to the fetus is dependent upon transplacental transport and provides the backbone for the biosynthesis of biological membranes, myelin and various signalling molecules. The primary objective of this research was to elucidate the expression patterns of genes that regulate fatty acid transport across the placenta. Several fatty acid transport regulatory genes have been identified in the rat including; cytoplasmic heart fatty acid binding protein (hFABP), plasma membrane fatty acid binding protein (FABPpm), fatty acid translocase (FAT) and fatty acid transport protein (FATP). In this study, we have elucidated temporal and spatial expression patterns for these genes in the rat placenta and in cell culture models of the rat placenta by Northern blot, RT-PCR, Western blot and/or by in situ hybridization analyses. Expression of hFABP was specific to the labyrinth zone, the main barrier and site of transplacental transport in the rat placenta. In addition, the levels of hFABP expression increased with gestational age, suggesting a growing requirement for fatty acid transport with advancing stages of pregnancy. FABPpm, FAT and FATP are expressed in both the junctional and labyrinth zones of the rat placenta. FAT was predominantly localized to the labyrinth zone by in situ hybridization analysis. The placental cell expression patterns of the genes involved in fatty acid transport were supported by our observations of HRP-1 (labyrinth zone) and Rcho-1 (junctional zone) trophoblast cell culture models. Given their cell surface location, we predict that FABPpm, FAT and FATP potentially participate in placental fatty acid uptake. The predominant expression of hFABP and FAT in the labyrinth zone of the chorioallantoic placenta implicates hFABP and FAT in the transplacental movement of fatty acids from maternal to fetal compartments. 相似文献
60.
Rennan Garcias Moreira Julia Maria SaraivaDuarte Alexandre Costa Pereira Martha SosaMacias Carlos GalavizHernandez Meddly Lesley Santolalla Wagner C. S. Magalhes Camila Zolini Thiago Peixoto Leal Zsolt Balzs Adrin Llerena Robert H. Gilman Jos Geraldo Mill Victor Borda Heinner Guio Timothy D. OConnor Eduardo TarazonaSantos Fernanda RodriguesSoares 《CTS Clinical and Translational Science》2022,15(6):1400