全文获取类型
收费全文 | 38771篇 |
免费 | 2512篇 |
国内免费 | 97篇 |
专业分类
耳鼻咽喉 | 448篇 |
儿科学 | 1434篇 |
妇产科学 | 948篇 |
基础医学 | 4731篇 |
口腔科学 | 462篇 |
临床医学 | 6453篇 |
内科学 | 6716篇 |
皮肤病学 | 401篇 |
神经病学 | 3723篇 |
特种医学 | 799篇 |
外国民族医学 | 1篇 |
外科学 | 3574篇 |
综合类 | 362篇 |
一般理论 | 49篇 |
预防医学 | 5501篇 |
眼科学 | 403篇 |
药学 | 2362篇 |
中国医学 | 44篇 |
肿瘤学 | 2969篇 |
出版年
2024年 | 30篇 |
2023年 | 323篇 |
2022年 | 449篇 |
2021年 | 847篇 |
2020年 | 602篇 |
2019年 | 938篇 |
2018年 | 1092篇 |
2017年 | 812篇 |
2016年 | 851篇 |
2015年 | 945篇 |
2014年 | 1328篇 |
2013年 | 2093篇 |
2012年 | 3033篇 |
2011年 | 3214篇 |
2010年 | 1711篇 |
2009年 | 1550篇 |
2008年 | 2784篇 |
2007年 | 2792篇 |
2006年 | 2732篇 |
2005年 | 2686篇 |
2004年 | 2473篇 |
2003年 | 2196篇 |
2002年 | 2107篇 |
2001年 | 236篇 |
2000年 | 199篇 |
1999年 | 266篇 |
1998年 | 434篇 |
1997年 | 337篇 |
1996年 | 260篇 |
1995年 | 209篇 |
1994年 | 216篇 |
1993年 | 208篇 |
1992年 | 128篇 |
1991年 | 115篇 |
1990年 | 92篇 |
1989年 | 99篇 |
1988年 | 90篇 |
1987年 | 79篇 |
1986年 | 83篇 |
1985年 | 82篇 |
1984年 | 99篇 |
1983年 | 76篇 |
1982年 | 90篇 |
1981年 | 99篇 |
1980年 | 70篇 |
1979年 | 41篇 |
1978年 | 31篇 |
1977年 | 38篇 |
1976年 | 21篇 |
1975年 | 24篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
Kathryn E Merkel Karen L Schmidt Rachel M Levenstein Jessie M VanSwearingen Barbara C Bentley 《Otolaryngology--head and neck surgery》2007,137(1):100-104
OBJECTIVES: Positive affect in individuals with a facial movement disorder may promote lip corner movement (zygomaticus major) during smiling. We investigated whether a positive affect marker (orbicularis oculi activity) observed in an initial clinic visit of individuals with facial movement disorder (N = 28) predicted increased lip corner movement at a subsequent visit. STUDY DESIGN AND SETTING: In this clinical outcomes study, lip corner movement was assessed with the use of automated facial analysis. Asymmetry of movement was compared in individuals who smiled with or without the positive affect marker at an initial clinic visit. RESULTS: The positive affect marker at the initial visit was associated with a reduction in the asymmetry of the lip corner movement at the second visit. CONCLUSION: Positive affect predicts improved facial movement outcomes in patients with facial movement disorders. SIGNIFICANCE: Positive emotion in facial movement patients may be an important factor in recovery of facial movement during therapy. 相似文献
72.
Comorbidities in head and neck cancer: agreement between self-report and chart review. 总被引:1,自引:1,他引:0
Shraddha S Mukerji Sonia A Duffy Karen E Fowler Mumtaz Khan David L Ronis Jeffrey E Terrell 《Otolaryngology--head and neck surgery》2007,136(4):536-542
OBJECTIVES: To determine the accuracy of self-reported comorbidities compared with medical record review and the clinical and sociodemographic characteristics associated with accuracy of self-reported comorbidities. STUDY DESIGN: We conducted a prospective study of 458 newly diagnosed head and neck cancer patients using self-administered questionnaire and medical chart review data. Overall and itemwise consistency between self-report and chart review was evaluated. Social, clinical, and demographic characteristics of consistent versus inconsistent responders were analyzed. RESULTS: Seventy-four percent of patients had at least one comorbidity. There was good overall consistency between self-report and chart review (kappa = 0.50). Compared with consistent responders, inconsistent responders were found to be older (P < 0.05), have lower sleep (P < 0.05) and physical activity scores (P < 0.05), be more depressed (P < 0.05), and have more severe comorbidities (P < 0.05). CONCLUSIONS AND SIGNIFICANCE: Self-report may be considered as an alternative to chart review for comorbidity assessment in head and neck cancer patients. Younger patients, those with good general health, fewer depressive symptoms, and mild comorbidities, are more likely to give responses consistent with chart review. 相似文献
73.
Manjula K. Gupta Karen Seifarth Sharad D. Deodhar O. P. Schumacher 《Journal of clinical laboratory analysis》1987,1(1):124-128
A sensitive, simultaneous sandwich enzyme immunoassay for TSH was evaluated especially for its ability to distinguish hyperthyroid patients from the euthyroid population. A total of 140 patient samples was analzyed by this assay as well as with a two-step sandwich radioimmunoassay. The diagnostic sensitivity of the thyrotropin assay was 92.5% and the specificity was 88%. False negatives by thyrotropin assay included two patients with Graves' disease who were being treated with propranolol at the time of testing and one patient who was considered hyperthyroid while receiving synthroid. Twelve patients with elevated free thyroxine index levels were considered euthyroid and 50% of these had thyrotropin values that were undetectable; most were elderly patients with nonthyroidal illnesses. Although the thyrotropin enzyme immunoassay had good sensitivity and precision for the detection of hyperthyroidism, our data suggest the limitation of a single thyrotropin determination in establishing the euthyroid state, especially in elderly patients with associated nonthyroidal illnesses and hyperthyroxinemia. 相似文献
74.
75.
Changes in depression during and following pregnancy 总被引:1,自引:0,他引:1
David M. Fergusson L. John Horwood Karen Thorpe† 《Paediatric and perinatal epidemiology》1996,10(3):279-293
Summary. .Rates of depression were studied in a sample of over 9000 women who were participants in the Avon Longitudinal Study of Pregnancy and Childhood. Assessments of depression were made at 18 and 32 weeks gestation, and at 8 and 32 weeks postpartum. Changes in depressive status across time were modelled using latent Markov modelling methods. This analysis showed that when classification errors were taken into account there was relatively high stability in diagnostic status during pregnancy and after pregnancy. However, the transition from late pregnancy to the early postnatal period showed evidence of increased instability and remission of depression. The net effects of this were that rates of depression tended to decline following childbirth. The implications of these results for a series of issues including measurement errors in depression reports and the prevalence of depression before and after childbirth are discussed. 相似文献
76.
John F. Teare Roger W. Peterson Karen Authier Linda Schroeder Daniel L. Daly 《Child & youth care forum》1998,27(2):125-138
The purpose of this study was to examine the correlates of post-shelter maternal family satisfaction in a group of youth who
were reunified with their families following a shelter stay. Findings indicated that higher ratings of family satisfaction
were related to greater maternal problem solving skill and less family conflict. 相似文献
77.
Karen J. Chandross David C. Spray Rick I. Cohen Nalin M. Kumar Marian Kremer Rolf Dermietzel John A. Kessler 《Molecular and cellular neurosciences》1996,7(6):479-500
Schwann cell responses to nerve injury are stimulated, in part, by inflammatory cytokines. This study compares changes in the phenotype of cultured Schwann cells after exposure to the cytokine tumor necrosis factor (TNF)-α or the mitogen neu differentiation factor (NDF)-β. TNFα inhibited proliferation in a dose-dependent manner without altering Schwann cell survival. TNFα also reduced both gap junctional conductance and Lucifer yellow dye coupling between Schwann cells. Moreover, both P0and glial fibrillary acidic protein (GFAP) immunoreactivity were reduced. By contrast, NDFβ initially had little effect on cell division although it reduced junctional coupling within 8 h. However, by 48 h, NDFβ stimulated proliferation with a concomitant increase in coupling. Dividing Schwann cells (BrdU+) were preferentially dye coupled compared to nondividing cells, indicating an association between proliferation and coupling. Moreover, cultured Schwann cells expressed connexin46 mRNA and protein, and changes in the levels of the protein correlated with the degree of proliferation and coupling. The data thus provide evidence for cytokine-induced modulation of Schwann cell antigenic phenotype, proliferation, and gap junction properties. These observations suggest that enhanced gap junctional communication among Schwann cells after nerve injury could help to coordinate cellular responses to the injury, and that TNFα may be a signal which terminates proliferation as well as junctional communication. 相似文献
78.
79.
Stocker Karen J.; Howard Wayne R.; Statham Joanne; Proudlock Raymond J. 《Mutagenesis》1996,11(5):493-496
Fluoranthene is a ubiquitous environmental pollutant. Althoughfluoranthene is mutagenic in bacterial and mammalian in vitrocell systems following metabolic activation by rat liver fraction,information on in vivo mutagenicity is lacking and studies ontumour initiating activity in mice are equivocal. In the presentstudy, the potential genetic hazard to man was assessed usingthe mouse bone marrow micronucleus and rat liver unscheduledDNA synthesis test systems. Fluoranthene did not show any evidenceof genotoxicity in either of the in vivo assays following acuteoral administration at levels of up to 2000 mg/kg b.w.
1To whom correspondence should be addressed 相似文献
80.
Stephen Hunter Terry Gramlich Karen Abbott Vijay Varma 《Genes, chromosomes & cancer》1993,8(3):172-177
Carcinoma of the esophagus shows a strong male predominance and other epidemiologic differences from cancers arising at other sites. In this study, the prevalence of Y chromosome loss in 29 carcinomas of the esophagus and 53 carcinomas arising elsewhere in the aerodigestive tract was assessed by in situ hybridization of formalin-fixed paraffin-embedded tissue sections. Absence of the Y chromosome was defined as (1) negative staining for Y in neoplastic cells with positive staining for Y in immediately adjacent nonneoplastic epithelial and stromal cells, (2) positive staining of neoplastic cells with control probes for chromosomes X and 17, and (3) similar results at different stringencies and levels of protein digestion. According to these criteria, absence of the Y chromosome was observed in 13 of 14 (93%) adenocarcinomas of the esophagus, 8 of 13 (62%) squamous cell carcinomas of the esophagus, and 5 of 53 (9%) carcinomas arising in other sites. For the neoplasms examined, Y chromosome deletion was strongly and selectively associated with carcinomas, particularly adenocarcinomas, of the esophagus (P < .0001). These findings suggest that Y chromosome loss may be pathogenetically significant in these neoplasms. © 1993 Wiley-Liss, Inc. 相似文献