全文获取类型
收费全文 | 76034篇 |
免费 | 5596篇 |
国内免费 | 163篇 |
专业分类
耳鼻咽喉 | 607篇 |
儿科学 | 2822篇 |
妇产科学 | 2503篇 |
基础医学 | 9257篇 |
口腔科学 | 1024篇 |
临床医学 | 13286篇 |
内科学 | 13693篇 |
皮肤病学 | 1136篇 |
神经病学 | 6983篇 |
特种医学 | 1378篇 |
外国民族医学 | 33篇 |
外科学 | 6523篇 |
综合类 | 971篇 |
一般理论 | 129篇 |
预防医学 | 10662篇 |
眼科学 | 875篇 |
药学 | 4275篇 |
1篇 | |
中国医学 | 106篇 |
肿瘤学 | 5529篇 |
出版年
2023年 | 451篇 |
2022年 | 653篇 |
2021年 | 1471篇 |
2020年 | 1059篇 |
2019年 | 1759篇 |
2018年 | 1963篇 |
2017年 | 1360篇 |
2016年 | 1596篇 |
2015年 | 1714篇 |
2014年 | 2305篇 |
2013年 | 3717篇 |
2012年 | 5272篇 |
2011年 | 5536篇 |
2010年 | 2976篇 |
2009年 | 2755篇 |
2008年 | 4956篇 |
2007年 | 5523篇 |
2006年 | 5345篇 |
2005年 | 5148篇 |
2004年 | 4962篇 |
2003年 | 4701篇 |
2002年 | 4434篇 |
2001年 | 611篇 |
2000年 | 459篇 |
1999年 | 605篇 |
1998年 | 1000篇 |
1997年 | 766篇 |
1996年 | 691篇 |
1995年 | 599篇 |
1994年 | 569篇 |
1993年 | 562篇 |
1992年 | 391篇 |
1991年 | 338篇 |
1990年 | 318篇 |
1989年 | 281篇 |
1988年 | 271篇 |
1987年 | 262篇 |
1986年 | 247篇 |
1985年 | 288篇 |
1984年 | 296篇 |
1983年 | 305篇 |
1982年 | 383篇 |
1981年 | 361篇 |
1980年 | 304篇 |
1979年 | 174篇 |
1978年 | 163篇 |
1977年 | 177篇 |
1976年 | 160篇 |
1975年 | 136篇 |
1974年 | 123篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
Tinghu Kang Yang Li Jiandong Guo Xingwen Ma Fatema Akhter Hiramoni Md Zahir Ahmed Mary C. Jobe Oli Ahmed 《International Journal of Mental Health Promotion, The》2022,24(2):207-217
The aim of the study was to explore the relationship between college graduates’ dual self-consciousness, job search
clarity and perceived stress, and reveal the mediating role of perceived stress between dual self-consciousness and
job search clarity. In this study, 467 college graduates were investigated using the Dual Self-Consciousness Scale,
Job Search Clarity Scale, and Perceived Stress Scale. After controlling for gender, age, and region, the results
revealed that: (1) private self-consciousness has a significant positive predictive effect on job search clarity; (2)
perceived stress has a significant negative predictive effect on job search clarity; (3) perceived stress plays partial
mediation effects between private self-consciousness and job search clarity; (4) perceived stress plays complete
mediation effects between public self-consciousness and job search clarity; (5) perceived stress has suppressing
effects between public self-consciousness and job search clarity. 相似文献
32.
33.
Reem Haj-Ali BDS DDS MS ; Mary Walker DDS PhD ; Karen Williams PhD ; Yong Wang PhD ; Paulette Spencer DDS PhD 《Journal of prosthodontics》2006,15(2):82-88
PURPOSE: The purpose of this study was to compare the dentin/adhesive interfacial characteristics when bonding to noncarious as well as caries-affected dentin. MATERIALS AND METHODS: Seven extracted, unerupted, third molars were sectioned into halves. Artificial caries was created on one-half of each tooth, leaving the other half as a control. Dentin surfaces were treated with UNO adhesive according to the manufacturer's instructions for the wet-bonding technique and under environmental conditions present in the oral cavity. Dentin/adhesive interface sections of each half-tooth were stained with Goldner's trichrome, a classic bone stain, and examined using light microscopy. The width of exposed collagen was measured directly from photomicrographs, and adhesive penetration was analyzed qualitatively. RESULTS: The degree and extent to which the adhesive encapsulated the demineralized dentin matrix were reflected in the color difference in the stained sections with the noncarious dentin sections showing a degree of collagen encapsulation superior to that of the caries-affected dentin sections. The overall mean widths of exposed collagen were significantly (p < or = .05) greater at the caries-affected dentin/adhesive interface, 8.6 (1.7) microm, as compared with those at the noncarious dentin/adhesive interface, 6.0 (1.5) microm. CONCLUSIONS: The morphologic characteristics of the caries-affected dentin/interface suggest an increase in the exposed collagen zone and a decrease in the quality of the adhesive infiltration when compared with noncarious dentin. The evidence suggests that dentin substrate characteristics have a significant effect on the dentin/adhesive interface structure. 相似文献
34.
Joseph Biederman Haitao Gao Ann K Rogers Thomas J Spencer 《Neuropsychopharmacology》2006,60(10):1106-1110
BACKGROUND: The validity of parent reports regarding children's attention-deficit/hyperactivity disorder (ADHD) symptoms has been questioned. This study assessed whether parent reports were as sensitive as teacher reports to document change in ADHD symptoms during clinical trials with atomoxetine. METHODS: Data were compared from two randomized, double-blind, placebo-controlled clinical trials of atomoxetine using different versions (parent or teacher) of the same rating scale (Attention-Deficit/Hyperactivity Disorder Rating Scale-IV [parent or teacher] Version: Investigator Administered and Scored - ADHD RS). Exclusion criteria included history of bipolar disorder, psychosis, seizures, alcohol abuse, or positive drug screen. Patients (6-16 years old) were treated with atomoxetine (titrated to a maximum dose of 1.8 mg/kg/day) administered once daily for up to 7 weeks. Parent and teacher ratings were compared using an analysis of covariance (ANCOVA) model. RESULTS: The analysis (n = 318) showed that treatment effects (mean change, baseline to endpoint) were similar between parent and teacher ratings (total, p = .762; inattention, p = .519; hyperactive/impulsive, p = .955). Effect sizes also were similar based on total scores (parent ratings = .69; teacher ratings = .63). CONCLUSIONS: Parent reports are as sensitive as teacher reports in assessing the efficacy of long-acting pharmacologic treatment for ADHD in children during clinical trials using the nonstimulant atomoxetine. 相似文献
35.
Jonathan Halford Gandis Mazeika Susan Slifer Marcy Speer Ann M Saunders Warren J Strittmatter Joel C Morgenlander 《Movement disorders》2006,21(4):540-542
Ninety-seven inpatients with tardive dyskinesia (average AIMS score = 13), the majority of whom were schizophrenic, were studied. Forty patients were Caucasian, and 57 were African-American. The APOE genotypes of these patients were compared to previously published genotypes of controls and with previously published studies of APOE genotypes in patients with schizophrenia. There were no significant differences in APOE allele frequencies comparing the African-American tardive dyskinesia population and the African-American control groups. In contrast, significant (< 0.05) P values were obtained comparing the Caucasian tardive dyskinesia population to the Caucasian controls, when comparing allele frequencies and genotypic frequencies. This study suggests that Caucasians bearing an APOE2 allele are at increased risk of developing tardive dyskinesia, whereas African-Americans are not. APOE genotype-specific risks of both tardive dyskinesia and Alzheimer's disease that vary across populations could be due to recruitment of patients or controls or could be due to modifying effects of differing genetic or environmental backgrounds. The mechanism by which the APOE2 allele increases risk of tardive dyskinesia is not known. Further information about the mechanisms of increased risk of tardive dyskinesia could result in stratification of prescribing practices weighing the costs of medications against the relative risk of side effects. 相似文献
36.
Andrea DiMartini Nancy Day Mary Amanda Dew Lubna Javed Mary Grace Fitzgerald Ashok Jain John J Fung Paulo Fontes 《Liver transplantation》2006,12(5):813-820
For patients who receive a liver transplant (LTX) for alcoholic liver disease (ALD), investigators are focusing beyond survival to determine specific alcohol use outcomes. Studies suggest the use of alcohol ranges from 8 to 22% for the first post-transplant year with cumulative rates reaching 30 to 40% by 5 years following transplantation. Yet while investigators are interested in determining specific rates of alcohol use and predictors of use, only three studies since 1990 have been prospective. In 1998, we began a prospective study of post-LTX alcohol consumption in ALD recipients using multiple repeated measures of alcohol use. After 5 years of follow-up, we found that 22% had used any alcohol by the first year and 42% had a drink by 5 years. By 5 years, 26% drank at a heavier use (binge) pattern and 20% drank in a frequent pattern. In a univariate model, predictors of alcohol use included pre-transplant length of sobriety, a diagnosis of alcohol dependence, a history of other substance use, and prior alcohol rehabilitation. 相似文献
37.
Mary Ann Richardson Helen M Chao Laura L Read James D Clelland Raymond F Suckow 《American journal of medical genetics. Part B, Neuropsychiatric genetics》2006,(2):195-197
Phenylketonuria (PKU), an inborn error of phenylalanine metabolism, has been shown to be a risk factor for tardive dyskinesia (TD). In male psychiatric patients there was a significant relationship between TD and measures of plasma phenylalanine following ingestion of a standardized phenylalanine dose that was indicative of higher brain availability of phenylalanine in patients with TD. In addition, a medical food formulation consisting of branched chain amino acids, which compete with phenylalanine for transport across the blood-brain barrier, has been demonstrated to be an efficacious treatment for TD. Cumulatively these findings suggested that TD was related to phenylalanine metabolism and thus that sequence variants in the gene for phenylalanine hydroxylase (PAH), the rate-limiting enzyme in the catabolism of phenylalanine, could be associated with TD susceptibility. Genetic screening of PAH in a group of 123 psychiatric patients revealed ten sequence polymorphisms and two mutations, but none appeared to be a significant risk factor for TD. 相似文献
38.
Kalaichelvi Ganesalingam Ann Sanson Vicki Anderson Keith Owen Yeates 《Journal of the International Neuropsychological Society》2006,12(5):609-621
This study examined the impact of childhood traumatic brain injury (TBI) on self-regulation and social and behavioral functioning, and the role of self-regulation as a predictor of children's social and behavioral functioning. Participants included 65 children with moderate to severe TBI and 65 children without TBI, all between 6 and 11 years of age. Self-regulation and social and behavioral functioning were assessed 2 to 5 years following injury. Children with TBI displayed deficits in self-regulation and social and behavioral functioning, after controlling for socioeconomic status (SES), although the magnitude of the deficits was not related to injury severity. Self-regulation accounted for significant variance in children's social and behavioral functioning, after controlling for SES and group membership. Self-regulation may be an important determinant of children's social and behavioral functioning following TBI. 相似文献
39.
Lipid peroxidation, occupational stress and aging in workers of a prehospital emergency service. 总被引:2,自引:0,他引:2
Angela Casado Nieves De Lucas Encarnación López-Fernández Alberto Sánchez José-Antonio Jimenez 《European journal of emergency medicine》2006,13(3):165-171
BACKGROUND: Stressful conditions lead to formation of excessive free radicals, and lipid peroxidation is one of the major outcomes of free radical-mediated injury that directly damages membranes and generates a number of secondary products. OBJECTIVES: To determine the levels of malondialdehyde, an end product of lipid peroxidation, according to demographic and occupational variables in workers of a prehospital emergency service and to analyse the relationship between malondialdehyde levels and burnout. MATERIAL AND METHODS: One hundred and eleven healthy workers of a prehospital emergency service and eighty aged-matched healthy individuals of both sexes as a control group were surveyed. Malondialdehyde levels were measured by the Bull and Marnett method. To measure burnout, the Maslach Burnout Inventory was used. RESULTS: Professional category is associated with lipid peroxidation and burnout levels (Malondialdehyde levels were: physicians 338.10+/-14.47, nurses 329.17+/-12.62 and technicians 296.74+/-14.28; burnout levels were: physicians 41.29+/-3.59, nurses 37.38+/-6.05 and technicians 35.33+/-5.87). Working at night and in the evening increased malondialdehyde and burnout levels. Malondialdehyde levels increase with age. No significant variations with respect to sex were detected. Significant variations in malondialdehyde levels were detected between singles (303.13+/-12.74) and married people (344.43+/-13.43) but not with respect to divorcees (326.44+/-11.74). Significant differences were detected in erythrocyte malondialdehyde levels between smokers (341.37+/-17.09) and nonsmokers (302.21+/-12.38), but not for alcohol consumption. CONCLUSIONS: These findings suggest a positive correlation between malondialdehyde, a biomarker of lipid peroxidation and occupational stress, as estimated by elements of the Maslach Burnout Inventory, and oxidative stress. 相似文献
40.