全文获取类型
收费全文 | 5386篇 |
免费 | 443篇 |
国内免费 | 20篇 |
专业分类
耳鼻咽喉 | 30篇 |
儿科学 | 108篇 |
妇产科学 | 151篇 |
基础医学 | 730篇 |
口腔科学 | 243篇 |
临床医学 | 498篇 |
内科学 | 1353篇 |
皮肤病学 | 119篇 |
神经病学 | 420篇 |
特种医学 | 160篇 |
外科学 | 615篇 |
综合类 | 69篇 |
一般理论 | 3篇 |
预防医学 | 714篇 |
眼科学 | 71篇 |
药学 | 303篇 |
中国医学 | 57篇 |
肿瘤学 | 205篇 |
出版年
2023年 | 34篇 |
2022年 | 98篇 |
2021年 | 140篇 |
2020年 | 74篇 |
2019年 | 114篇 |
2018年 | 136篇 |
2017年 | 108篇 |
2016年 | 99篇 |
2015年 | 119篇 |
2014年 | 165篇 |
2013年 | 235篇 |
2012年 | 369篇 |
2011年 | 396篇 |
2010年 | 179篇 |
2009年 | 183篇 |
2008年 | 301篇 |
2007年 | 304篇 |
2006年 | 288篇 |
2005年 | 267篇 |
2004年 | 223篇 |
2003年 | 218篇 |
2002年 | 222篇 |
2001年 | 129篇 |
2000年 | 121篇 |
1999年 | 110篇 |
1998年 | 36篇 |
1997年 | 32篇 |
1996年 | 37篇 |
1995年 | 38篇 |
1994年 | 36篇 |
1993年 | 25篇 |
1992年 | 78篇 |
1991年 | 83篇 |
1990年 | 80篇 |
1989年 | 57篇 |
1988年 | 60篇 |
1987年 | 56篇 |
1986年 | 52篇 |
1985年 | 67篇 |
1984年 | 46篇 |
1983年 | 38篇 |
1981年 | 21篇 |
1980年 | 27篇 |
1979年 | 41篇 |
1978年 | 26篇 |
1977年 | 24篇 |
1976年 | 33篇 |
1975年 | 23篇 |
1974年 | 32篇 |
1969年 | 17篇 |
排序方式: 共有5849条查询结果,搜索用时 11 毫秒
91.
Social interactions in rodents are rewarding and motivating and social isolation is aversive. Accumulating evidence suggests that disruption of the social environment in adolescence has long-term effects on social interactions, on anxiety-like behavior and on stress reactivity. In previous work we showed that adolescent isolation produced increased reactivity to acute and to repeated stress in female rats, whereas lower corticosterone responses to acute stress and decreased anxiety-related behavior were noted in isolated males. These results indicate a sex specific impact on the effects of social stress in adolescence. However, little is known about whether social isolation impacts behaviors related to affect and whether it does so differently in male and female rats. The present study investigated the impact of adolescent social isolation from day 30-50 of age in male and female Sprague Dawley rats on behavior in the forced swim test at the end of adolescence and in adulthood and on behavior in the sucrose preference test in adulthood. Adult female rats that were isolated in adolescence exhibited increased climbing on the first and second day of the forced swim test and showed an increased preference for sucrose compared to adult females that were group-housed in adolescence. There were no effects in male rats. The results indicate that social isolation in adolescence produces a stable and active behavioral phenotype in adult female rats. 相似文献
92.
Antigen-induced inhibition of human in vitro spontaneous IgE synthesis. I. Factors and kinetic studies. 下载免费PDF全文
V Urea I Moneo M Cuevas I Reymundo M Luz Diez Gomez E Alvarez Cuesta A Bootello 《Clinical and experimental immunology》1985,59(3):687-694
Peripheral blood mononuclear cells from patients with hypersensitivity to L. perenne and D. pteronyssinus were incubated with specific antigen. They were then cultured for 7 days in the absence of antigen and the IgE contained in the supernatants was determined using an enzyme immunoassay (ELISA). Pre-incubation of the cells with antigen produced an inhibitory effect on the spontaneous IgE synthesis in most of the cases (101 of the 134 individual studied). This inhibition was more pronounced and more frequent in those cultures with an elevated spontaneous production of IgE (3,000-10,000 pg/ml). This effect depended on the dose of antigen and the duration of cell exposure. Both spontaneous IgE production kinetics and antigen-mediated inhibition were studied. A study of the IgE content of the cell pellets indicated that the antigen did not induce inhibition of the IgE release. We therefore believe that the inhibition observed must be due to some kind of IgE synthesis suppression. 相似文献
93.
Castañeda-Bueno M Cervantes-Pérez LG Vázquez N Uribe N Kantesaria S Morla L Bobadilla NA Doucet A Alessi DR Gamba G 《Proceedings of the National Academy of Sciences of the United States of America》2012,109(20):7929-7934
Pseudohypoaldosteronism type II is a salt-sensitive form of hypertension with hyperkalemia in humans caused by mutations in the with-no-lysine kinase 4 (WNK4). Several studies have shown that WNK4 modulates the activity of the renal Na(+)Cl(-) cotransporter, NCC. Because the renal consequences of WNK4 carrying pseudoaldosteronism type II mutations resemble the response to intravascular volume depletion (promotion of salt reabsorption without K(+) secretion), a condition that is associated with high angiotensin II (AngII) levels, it has been proposed that AngII signaling might affect WNK4 modulation of the NCC. In Xenopus laevis oocytes, WNK4 is required for modulation of NCC activity by AngII. To demonstrate that WNK4 is required in the AngII-mediated regulation of NCC in vivo, we used a total WNK4-knockout mouse strain (WNK4(-/-)). WNK4 mRNA and protein expression were absent in WNK4(-/-) mice, which exhibited a mild Gitelman-like syndrome, with normal blood pressure, increased plasma renin activity, and reduced NCC expression and phosphorylation at T-58. Immunohistochemistry revealed normal morphology of the distal convoluted tubule with reduced NCC expression. Low-salt diet or infusion of AngII for 4 d induced phosphorylation of STE20/SPS1-related proline/alanine-rich kinase (SPAK) and of NCC at S-383 and T-58, respectively, in WNK4(+/+) but not WNK4(-/-) mice. Thus, the absence of WNK4 in vivo precludes NCC and SPAK phosphorylation promoted by a low-salt diet or AngII infusion, suggesting that AngII action on the NCC occurs via a WNK4-SPAK-dependent signaling pathway. Additionally, stimulation of aldosterone secretion by AngII, but not by a high-K(+) diet, was impaired in WNK4(-/-) mice. 相似文献
94.
Pasiakos SM Mettel JB West K Lofgren IE Fernandez ML Koo SI Rodriguez NR 《Metabolism: clinical and experimental》2008,57(4):458-464
The number of contemporary diet plans promoting high protein intakes for weight management has increased dramatically. Complementing this dietary approach with increased physical activity has proven to be beneficial. Recent studies have suggested that protein intakes in excess of the current Recommended Dietary Allowance (0.8 g/kg) may be of metabolic benefit during weight loss. This investigation assessed changes in resting energy expenditure and substrate oxidation in overweight and obese premenopausal women in response to a weight loss intervention that combined a high-protein, reduced-calorie diet with increased physical activity. Thirty-nine overweight and obese premenopausal women (age, 30.9 +/- 1.5 years; body mass index, 30.2 +/- 0.5 kg/m2) participated in a 10-week weight loss program in which they ate a reduced-calorie diet for which protein provided 30% of total energy and approximated 1.4 g/kg. Subjects incrementally increased physical activity (ie, steps walking) throughout the diet intervention period. Resting energy expenditure, substrate oxidation, and body composition were assessed before (PRE) and after (POST) the 10-week weight loss program. Subjects experienced a 5% decrease in body weight, with significant decreases in both fat mass (PRE, 35.5 +/- 1.2 kg; POST, 32.4 +/- 1.1 kg; P < .0001) and fat-free mass (PRE, 44.6 +/- 0.7 kg; POST, 43.6 +/- 0.7 kg; P < .0001). Changes in body weight or body composition did not alter resting energy expenditure. Protein oxidation increased (PRE, 18% +/- 1%; POST, 20% +/- 1%; P < .05) and fat oxidation decreased (PRE, 37% +/- 3%; POST, 30% +/- 3%; P < .05) after the 10-week intervention. These findings illustrate that a weight loss intervention combining consumption of a high-protein, reduced-calorie diet with increased physical activity promotes weight loss without negatively impacting resting energy expenditure in this population of women. 相似文献
95.
GJ Ruiz-Delgado D Gómez-Almaguer LC Tarín-Arzaga OG Cantú-Rodriguez CA Urdaneta U Rodríguez-Morales J Calderón-Garcia O Fernández-Vargas M Montes-Montiel M Sánchez-Cárdenas GJ Ruiz-Argüelles 《Hematology (Amsterdam, Netherlands)》2012,17(4):193-197
Rituximab (R) has changed the prognosis of patients with non-Hodgkin's lymphoma (NHL) in developed countries, but its role has not been analyzed in underprivileged circumstances. One hundred and two patients with NHL treated in a developing country were analyzed: 28 patients with follicular lymphoma (FL) and 74 with diffuse large B-cell lymphoma (DLCL). Patients were treated upfront with either cyclophosphamide, doxorubicin, vincristine, and prednisone (CHOP) or R-CHOP; the decision to employ R depending solely on the ability of patients to defray it. In DLCL, 42 were given CHOP and 32 R-CHOP, whereas in FL, 19 were given CHOP and 9 R-CHOP. The impact of the addition of R was found to be clearer in FL than in DLCL. In patients with DLCL, the overall survival (OS) was 87% at 80 months for those treated with R-CHOP and 84% at 145 months for those treated with CHOP (not significant). In patients with FL, the OS was 89% at 88 months for those treated with R-CHOP and 71% at 92 months for those treated with CHOP (P = 0··05). In a multivariate analysis, other variables which were identified to be associated with the OS were IPI and number of cycles in DLCL. It is concluded that R produced a mild positive impact in the OS of patients with FL, but not in those with DLCL. Since the addition of R results in a 36-fold increase in treatment costs, these observations may be important to decide therapeutic approaches in NHL patients living in underprivileged circumstances. 相似文献
96.
JAK2V617F monitoring in polycythemia vera and essential thrombocythemia: Clinical usefulness for predicting myelofibrotic transformation and thrombotic events 下载免费PDF全文
Alberto Alvarez‐Larrán Beatriz Bellosillo Arturo Pereira Ana Kerguelen Juan Carlos Hernández‐Boluda Luz Martínez‐Avilés Concepción Fernández‐Rodríguez Montse Gómez Luis Lombardía Anna Angona Águeda Ancochea Alicia Senín Raquel Longarón Blanca Navarro María Collado Carlos Besses 《American journal of hematology》2014,89(5):517-523
The JAK2V617F allele burden has been identified as a risk factor for vascular events and myelofibrotic transformation in polycythemia vera (PV) and essential thrombocythemia (ET). However, all previous studies have evaluated a single time point JAK2V617F measurement. Therefore, the frequency and the clinical significance of changes in the JAK2V617F mutant load occurring during the disease evolution remain unknown. In the present study, JAK2V617F monitoring was performed during the follow‐up of 347 patients (PV = 163, ET = 184). According to their JAK2V617F evolutionary patterns, patients were stratified as stable < 50% (n = 261), stable ≥50% (n = 52), progressive increase (n = 24) and unexplained decrease (n = 10). After a 2,453 person‐years follow‐up, a total of 59 thrombotic events, 16 major hemorrhages, and 27 cases of myelofibrotic transformations were registered. At multivariate analyses, patients with a persistently high (≥50%) or unsteady JAK2V617F load during follow‐up had an increased risk of myelofibrotic transformation (Incidence rate ratio [IRR]: 20.7, 95% CI: 6.5–65.4; P < 0.001) and a trend for a higher incidence of thrombosis (IRR: 1.7, 1–3.3; P = 0.05) than patients with a stable allele burden below 50%. In conclusion, JAK2V617F monitoring could be useful in patients with PV and ET for predicting disease's complications, especially myelofibrotic transformation. Am. J. Hematol. 89:517–523, 2014. © 2014 Wiley Periodicals, Inc. 相似文献
97.
Sharon E. Jacob M.D. Alina Goldenberg M.D. M.A.S. Janice L. Pelletier M.D. Luz S. Fonacier M.D. Richard Usatine M.D. Nanette Silverberg M.D. 《Pediatric dermatology》2015,32(6):779-785
Nickel is the leading cause of allergic contact dermatitis (ACD) from early childhood through adolescence. Studies have shown that skin piercings and other nickel‐laden exposures can trigger the onset of nickel ACD in those who are susceptible. Nickel ACD causes a vast amount of cutaneous disease in children. Cases of nickel ACD in children have been reported in peer‐reviewed literature from 28 states. Common items that contain inciting nickel include jewelry, coins, zippers, belts, tools, toys, chair studs, cases for cell phones and tablets, and dental appliances. The diagnosis of nickel ACD has been routinely confirmed by patch testing in children older than 6 months suspected of ACD from nickel. Unlike in Europe, there are no mandatory restrictions legislated for nickel exposure in the United States. Denmark has demonstrated that regulation of the nickel content in metals can lower the risk of ACD and the associated health care–related costs that arise from excess nickel exposure. To further awareness, this article reviews the prominent role of nickel in pediatric skin disease in the United States. It discusses the need for a campaign by caretakers to reduce nickel‐related morbidity. Lastly, it promotes the model of European legislation as a successful intervention in the prevention of nickel ACD. 相似文献
98.
Silvia Goñi Esarte Antonio Arín Letamendía Juan José Vila Costas Francisco Javier Jiménez Pérez David Ruiz-Clavijo García Juan Carrascosa Gil María Luz Almendral López 《Gastroenterologia y hepatologia》2013
Esophageal lichen planus (ELP) is a rare condition with unknown prevalence that can sometimes be underestimated due to the subtle and nonspecific findings of diagnostic workup. Oral lesions rarely extend to the esophageal mucosa, but when they do, the most frequent symptoms are dysphagia and odynophagia. There is often a significant delay in diagnosis and inadequate treatment. We report the case of a 59-year-old woman diagnosed with ELP, successfully treated with rituximab, a chimeric monoclonal antibody that depletes CD20+B cells. To our knowledge, this is only the second report of this treatment in ELP. 相似文献
99.
100.
Tôrres Luísa Helena do Nascimento Silva Débora Dias da Neri Anita Liberalesso Hilgert Juliana Balbinot Hugo Fernando Neves Sousa Maria da Luz Rosário de 《Nutrition (Burbank, Los Angeles County, Calif.)》2013,29(1):152-157
ObjectivePoor oral status, represented by partial/complete tooth loss, may lead to changes in food choice, which may ultimately lead to underweight, overweight, or obesity. The aim of this study is to evaluate whether poor oral status is associated with underweight or overweight/obesity, regardless of physical activity.MethodsThis cross-sectional study is part of a major project, The Frailty in Brazilian Elderly Study, carried out in Campinas, Brazil (2008–2009). The sample was composed of 900 independent-living older adults. Complete data were available for 875 individuals including sociodemographic, self-reported amount of medications used and eating difficulty questionnaire, smoking habit, depressive symptoms, physical activity, oral examination, and anthropometric assessments according to the WHO criteria. Body mass index was used as an outcome. Multinomial logistic regression was adjusted for confounding variables.ResultsThe mean age of the sample was 72.7 y (±5.81) and the prevalence of edentulism was 47.7%. Edentate individuals not wearing dentures were more likely to be underweight [odds ratio (OR) = 3.94, 95% confidence interval (CI) 1.14–13.64] and overweight/obese (OR = 2.88, 95%CI 1.12–7.40). Males (OR = 0.56, 95%CI 0.36–0.85) and those not using medications (OR = 0.41 95%CI 0.24–0.70) were less likely to be overweight/obese. Individuals who smoke (OR = 2.62, 95%CI 1.26–5.44) were more likely to be underweight. Older individuals with family income between 3.1 and 5 minimum wage (OR = 1.69, 95%CI 1.00–2.87) were more likely to be overweight/obese.ConclusionTo our knowledge, this is one of the first studies associating poor oral health, represented by edentulism not rehabilitated with dentures, with unfavorable body mass, regardless of the two major confounders, physical activity and depression symptoms. 相似文献