全文获取类型
收费全文 | 6469篇 |
免费 | 475篇 |
国内免费 | 16篇 |
专业分类
耳鼻咽喉 | 82篇 |
儿科学 | 137篇 |
妇产科学 | 181篇 |
基础医学 | 893篇 |
口腔科学 | 216篇 |
临床医学 | 805篇 |
内科学 | 1125篇 |
皮肤病学 | 117篇 |
神经病学 | 694篇 |
特种医学 | 272篇 |
外科学 | 690篇 |
综合类 | 63篇 |
一般理论 | 3篇 |
预防医学 | 722篇 |
眼科学 | 85篇 |
药学 | 541篇 |
中国医学 | 4篇 |
肿瘤学 | 330篇 |
出版年
2021年 | 93篇 |
2020年 | 55篇 |
2019年 | 94篇 |
2018年 | 110篇 |
2017年 | 84篇 |
2016年 | 79篇 |
2015年 | 93篇 |
2014年 | 147篇 |
2013年 | 235篇 |
2012年 | 307篇 |
2011年 | 365篇 |
2010年 | 174篇 |
2009年 | 149篇 |
2008年 | 264篇 |
2007年 | 305篇 |
2006年 | 258篇 |
2005年 | 243篇 |
2004年 | 216篇 |
2003年 | 236篇 |
2002年 | 221篇 |
2001年 | 231篇 |
2000年 | 246篇 |
1999年 | 179篇 |
1998年 | 95篇 |
1997年 | 78篇 |
1996年 | 63篇 |
1995年 | 60篇 |
1994年 | 60篇 |
1993年 | 58篇 |
1992年 | 152篇 |
1991年 | 151篇 |
1990年 | 146篇 |
1989年 | 140篇 |
1988年 | 146篇 |
1987年 | 137篇 |
1986年 | 116篇 |
1985年 | 119篇 |
1984年 | 81篇 |
1983年 | 65篇 |
1982年 | 62篇 |
1981年 | 55篇 |
1979年 | 80篇 |
1978年 | 63篇 |
1977年 | 53篇 |
1976年 | 59篇 |
1975年 | 51篇 |
1973年 | 53篇 |
1972年 | 50篇 |
1971年 | 43篇 |
1970年 | 54篇 |
排序方式: 共有6960条查询结果,搜索用时 15 毫秒
51.
Riegel Barbara Carlson Beverly Glaser Dale Romero Tomas 《Quality of life research》2003,12(6):689-698
Hispanics are a growing ethnic minority in the United States and one at significant risk for heart failure. Health-related quality of life (HRQL) is poor in individuals with heart failure, especially during and immediately following hospitalization. No prior research into the HRQL of Hispanics with heart failure was located. A sample of 80 individuals with heart failure, evenly divided by primary language and matched on functional status using the New York Heart Association classification system and age, was studied for 6 months following hospital discharge. Data on HRQL were collected using Spanish and English versions of the Minnesota Living with Heart Failure Questionnaire. Scores improved over time in both groups but significantly more so in the Hispanics when compared to the non-Hispanics. Group differences in HRQL could not be explained by demographics, clinical characteristics, treatment received, perceived support, or instrument response characteristics. Further exploration of this naturally occurring phenomenon may provide insight into how HRQL can be improved in the general heart failure population. 相似文献
52.
Reny De Leeuw Elizangela Bertoli John E Schmidt Charles R Carlson 《Oral surgery, oral medicine, oral pathology, oral radiology, and endodontics》2005,99(5):558-568
OBJECTIVE: There is a high comorbidity between symptoms of post-traumatic stress disorder (PTSD) and chronic pain incidence. The objective of this investigation was to determine the prevalence of PTSD symptoms in chronic orofacial pain patients. STUDY DESIGN: The study included 1478 adult patients (mean age 36.4 +/- 12.7 years) with primary diagnoses of masticatory/cervical muscle pain or temporomandibular joint pain. Patients completed a battery of psychometric questionnaires including a screening for PTSD symptoms. The sample was divided into a PTSD-positive group (n=218, 15%) a PTSD-negative group (n=551, 37%), and a no-stressor group (n=709, 48%) according to stressor incidence and symptom severity. RESULTS: The current prevalence of PTSD symptomatology was considerably higher than that reported in surveys from the general population. Patients in the PTSD-positive symptom group reported significantly higher psychological distress, sleep dysfunction, and pain severity compared to patients in the other groups. Psychological distress as measured by the SCL-90-R reached clinically significant levels only in those patients with PTSD symptomatology. CONCLUSIONS: The results of this study performed at a tertiary care center suggest that TMD patients without PTSD symptomatology show low levels of psychological distress, if any. Clinically significant levels of psychological distress are likely indicators for PTSD. PTSD screening should be included as part of a routine psychometric test battery in TMD patients. 相似文献
53.
54.
55.
Variations in human corneal endothelial cell morphology and permeability to fluorescein with age 总被引:1,自引:0,他引:1
Fluorophotometry with topically applied fluorescein and endothelial cell photography were performed on 80 normal subjects (age 5-79 yr). Variations in endothelial cell morphology and function, flow of aqueous humor, and intraocular pressure were recorded. The mean endothelial cell size was 332.3 +/- 46.3 micron 2. A 28% increase in endothelial cell size was measured over the eight decades (r = 0.53, P less than 0.001). The coefficient of variation of cell size also increased with age (r = 0.41, P less than 0.001). The percentage of hexagonal endothelial cells decreased by 14% (r = -0.48, P less than 0.001), while the percentage of pentagonal and heptagonal cells increased by 50% (r = 0.44, P less than 0.001) and 40% (r = 0.33, P less than 0.002), respectively, with age. The mean endothelial permeability to fluorescein was 4.03 +/- 0.63 x 10(-4) cm min-1. A 23% increase in endothelial permeability with age was observed (r = 0.44, P less than 0.001). No change in central corneal thickness or endothelial pump rate was found. Flow of aqueous humor remained stable with age, despite a 25% increase in intraocular pressure (r = 0.50, P less than 0.001). Polarization of fluorescence of fluorescein in the corneal stroma decreased with age (r = -0.46, P less than 0.001). We conclude that with age the human corneal endothelium becomes morphologically less regular and may become more permeable to fluorescein. 相似文献
56.
Maternal melatonin communicates daylength information to the fetus in Siberian hamsters. Fetal sensitivity to melatonin declines near birth. In this report, we describe melatonin receptor distribution and a second messenger response to melatonin in Siberian hamsters during the perinatal period. The sites of high-affinity 2-[125I]iodomelatonin ([125I]MEL) binding were generally similar throughout the perinatal period. The non-hydrolyzable GTP analog, guanosine-5'-O-(3-thiotriphosphate) (100 microM) inhibited [125I]MEL binding at each age, suggesting the melatonin receptors are associated with guanine nucleotide binding proteins (G proteins). Furthermore, melatonin (10 nM) inhibited forskolin-stimulated cAMP accumulation in median eminence/pars tuberalis (ME/PT) explants as early as 4 days before birth, when sensitivity to melatonin in vivo is high. The cAMP regulatory system appeared disrupted on the day of birth, in that forskolin (10 microM) stimulation of cAMP accumulation was reduced, and melatonin did not inhibit cAMP accumulation stimulated by forskolin. A higher forskolin dose (100 microM) elevated cAMP levels more clearly on the day of birth, and melatonin inhibited forskolin-stimulated cAMP accumulation. These results suggest that the decreased physiological responsiveness to melatonin at the end of gestation may be due to alterations in the cAMP regulatory system. 相似文献
57.
Isolation and characterization of an olfactory mutant in Drosophila with a chemically specific defect. 总被引:9,自引:3,他引:6
下载免费PDF全文
![点击此处可从《Proceedings of the National Academy of Sciences of the United States of America》网站下载免费的PDF全文](/ch/ext_images/free.gif)
S L Helfand J R Carlson 《Proceedings of the National Academy of Sciences of the United States of America》1989,86(8):2908-2912
A Drosophila mutant was isolated and shown to exhibit defective response to the chemical odorant benzaldehyde in two distinctly different behavioral assays. The defect exhibited chemical specificity: response to three other chemicals was normal. The mutant also showed abnormalities in pigmentation and fertility. Genetic mapping and complementation analysis provide evidence that the olfactory, pigmentation, and fertility defects arise as a result of a lesion at the pentagon locus. The specificity of the olfactory defect suggests the possibility that the mutation may define a molecule required in reception, transduction, or processing of a specific subset of chemical information in the olfactory system. 相似文献
58.
59.
Abstract The purpose of this study was to determine the physical activity participation patterns of college students when defined by their Health Locus of Control orientation. One thousand thirty-three college-aged students completed the Wellness Activity Profile, a questionnaire that yielded data on Health Locus of Control and self-reported frequency of participation in physical activities. Discriminant analyses indicated that the combination of physical activities associated with internally and externally oriented students were different for both males and females. Participation in high caloric expenditure activities was more frequent among internal subjects (Male: bicycling, volleyball, other individual sports, and snorkel/scuba diving; Female: basketball, weight training, tennis, fast walking/jogging/running, and judo/karate), while low caloric expenditure activities were associated with an external orientation (Male: baseball/softball, sailing, fishing, golf, and other recreational sports; Female: track and field jumping and fishing). 相似文献
60.
The nucleophosmin-anaplastic lymphoma kinase fusion protein induces c-Myc expression in pediatric anaplastic large cell lymphomas 总被引:4,自引:0,他引:4
下载免费PDF全文
![点击此处可从《The American journal of pathology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Raetz EA Perkins SL Carlson MA Schooler KP Carroll WL Virshup DM 《The American journal of pathology》2002,161(3):875-883
The majority of pediatric anaplastic large cell lymphomas (ALCLs) carry the t(2;5)(p23;q35) chromosomal translocation that juxtaposes the dimerization domain of nucleophosmin with anaplastic lymphoma kinase (ALK). The nucleophosmin-ALK fusion induces constitutive, ligand-independent activation of the ALK tyrosine kinase leading to aberrant activation of cellular signaling pathways. To study the early consequences of ectopic ALK activation, a GyrB-ALK fusion was constructed that allowed regulated dimerization with the addition of coumermycin. Expression of the fusion protein caused a coumermycin-dependent increase in cellular tyrosine phosphorylation and c-Myc immunoreactivity, which was paralleled by a rise in c-myc RNA. To assess the clinical relevance of this observation, c-Myc expression was determined in pediatric ALK-positive and -negative lymphomas. Co-expression of c-Myc and ALK was seen in tumor cells in 15 of 15 (100%) ALK-positive ALCL samples, whereas no expression of either ALK or c-Myc was seen in six of six cases of ALK-negative T-cell lymphoma. C-Myc may be a downstream target of ALK signaling and its expression a defining characteristic of ALK-positive ALCLs. 相似文献