全文获取类型
收费全文 | 15134篇 |
免费 | 936篇 |
国内免费 | 269篇 |
专业分类
耳鼻咽喉 | 306篇 |
儿科学 | 195篇 |
妇产科学 | 200篇 |
基础医学 | 2371篇 |
口腔科学 | 243篇 |
临床医学 | 1502篇 |
内科学 | 2916篇 |
皮肤病学 | 676篇 |
神经病学 | 1170篇 |
特种医学 | 1105篇 |
外科学 | 1876篇 |
综合类 | 76篇 |
一般理论 | 2篇 |
预防医学 | 500篇 |
眼科学 | 403篇 |
药学 | 1199篇 |
中国医学 | 186篇 |
肿瘤学 | 1413篇 |
出版年
2024年 | 11篇 |
2023年 | 126篇 |
2022年 | 381篇 |
2021年 | 539篇 |
2020年 | 324篇 |
2019年 | 444篇 |
2018年 | 503篇 |
2017年 | 404篇 |
2016年 | 622篇 |
2015年 | 881篇 |
2014年 | 988篇 |
2013年 | 1085篇 |
2012年 | 1491篇 |
2011年 | 1355篇 |
2010年 | 927篇 |
2009年 | 732篇 |
2008年 | 810篇 |
2007年 | 802篇 |
2006年 | 701篇 |
2005年 | 639篇 |
2004年 | 469篇 |
2003年 | 399篇 |
2002年 | 372篇 |
2001年 | 133篇 |
2000年 | 87篇 |
1999年 | 96篇 |
1998年 | 140篇 |
1997年 | 125篇 |
1996年 | 103篇 |
1995年 | 92篇 |
1994年 | 64篇 |
1993年 | 69篇 |
1992年 | 39篇 |
1991年 | 45篇 |
1990年 | 43篇 |
1989年 | 35篇 |
1988年 | 46篇 |
1987年 | 26篇 |
1986年 | 22篇 |
1985年 | 18篇 |
1984年 | 26篇 |
1983年 | 14篇 |
1982年 | 17篇 |
1981年 | 16篇 |
1980年 | 13篇 |
1979年 | 10篇 |
1978年 | 11篇 |
1977年 | 6篇 |
1973年 | 5篇 |
1967年 | 5篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
Depletion of glutathione in the substantia nigra is one of the earliest changes observed in Parkinson's disease (PD), and could initiate dopaminergic neuronal degeneration. Nevertheless, we have previously demonstrated that mesencephalic dopaminergic neurons in primary monolayer cultures are more resistant to the toxicity of glutathione depletion than nondopaminergic neurons. To extend this finding to a system that more closely resembles the in vivo situation, we characterized the effects of glutathione depletion on reaggregate cultures derived from ventral mesencephalic and their striatal target neurons, as well as supporting elements including glia. Dopaminergic neurons were found to be more resistant to the toxicity of buthionine-(S,R)-sulfoximine, an inhibitor of glutathione synthesis, than other nigrostriatal neurons, while striatal target cells exhibited an intermediate susceptibility when examined after 48 h. Glutathione depletion, however, decreased the intracellular content of catecholamines after 48 h and eventually led to the loss of dopaminergic neurons after 7 days. Our data indicate that the intrinsic resistance of dopaminergic neurons to the toxicity of glutathione depletion occurs in a variety of experimental paradigms, and suggest that global glutathione depletion alone is unlikely to account for the selective loss of dopaminergic neurons in PD. Rather, it is more likely that either the selective loss of glutathione from dopaminergic neurons, or the combination of glutathione loss with other insults contributes to the preferential death of dopaminergic neurons in PD. 相似文献
82.
Jane Dimmitt Champion PhD FNP CS ; Pat Kelly PhD FNP ; Rochelle N. Shain PhD ; Jeanna M. Piper MD 《The Journal of rural health》2004,20(3):279-285
CONTEXT: There is a need for community-based, culturally sensitive, cognitive-behavioral interventions to reduce sexual risk behavior among minority adolescents. Studies of adolescent risk and protective behaviors have focused on identifying modifiable psychosocial variables that predict differential outcomes for subsequent intervention efforts. Research has been scarce in studies of rural minority adolescent women. PURPOSE: To examine the protective and risk behaviors of these rural Mexican-American adolescent women and their relationship to physical or sexual abuse. METHODS: Mexican-American adolescent women aged 14-19 years were recruited through a rural health clinic and administered a self-report assessment for protective and risk behavior and sexual, physical, and psychological abuse. FINDINGS: Rural minority adolescent women endured high levels of psychological distress and many risk behaviors yet experienced few protective behaviors. Barriers to health care included access and confidentiality. Physically or sexually abused adolescents endured relatively greater risk and fewer protective behaviors than nonabused. CONCLUSIONS: Rural Mexican-American adolescent women may benefit from confidential identification and assessment of abuse history and risk and protective behaviors so that appropriate psychological treatment can accompany accessible medical treatment. The prevalence of risk behaviors and abuse among these women presents a need for development of behavioral interventions for risk reduction and promotion of health protective behaviors. 相似文献
83.
Vascular endothelial growth factor gene polymorphisms and risk of primary lung cancer. 总被引:17,自引:0,他引:17
Su Jeong Lee Sin Yeob Lee Hyo-Sung Jeon Sun Ha Park Jin Sung Jang Ga Young Lee Ji Woong Son Chang Ho Kim Won Kee Lee Sin Kam Rang Woon Park Tae-In Park Young Mo Kang In-San Kim Tae Hoon Jung Jae Yong Park 《Cancer epidemiology, biomarkers & prevention》2005,14(3):571-575
Angiogenesis is an essential process in the development, growth, and metastasis of malignant tumors including lung cancer. DNA sequence variations in the vascular endothelial growth factor (VEGF) gene may lead to altered VEGF production and/or activity, thereby causing interindividual differences in the susceptibility to lung cancer via their actions on the pathways of tumor angiogenesis. To test this hypothesis, we investigated the potential association between three VEGF polymorphisms (-460T > C, +405C > G, and 936C > T)/haplotypes and the risk of lung cancer in a Korean population. VEGF genotypes were determined in 432 lung cancer patients and 432 healthy controls that were frequency matched for age and sex. VEGF haplotypes were predicted using Bayesian algorithm in the phase program. Compared with the combined +405 CC and CG genotype, the +405 GG genotype found associated with a significantly decreased risk of small cell carcinoma [SCC; adjusted odds ratio (OR), 0.36; 95% confidence interval (95% CI), 0.17-0.78]. The 936 CT genotype and the combined 936 CT and TT genotype were also associated with a significantly decreased risk of SCC compared with the 936 CC genotype (adjusted OR, 0.47; 95% CI, 0.26-0.85 and adjusted OR, 0.44; 95% CI, 0.24-0.80, respectively). Haplotype CGT was associated with a significantly decreased risk of SCC (adjusted OR, 0.39; 95% CI, 0.18-0.87), whereas haplotype TCC conferred a significantly increased risk of SCC (adjusted OR, 1.63; 95% CI, 1.14-2.33). None of the VEGF polymorphisms studied significantly influenced the susceptibility to lung cancer except SCC. However, haplotypes TCT and TGT were significantly associated with the risk of overall lung cancer, respectively (adjusted OR, 0.38; 95% CI, 0.25-0.60 and adjusted OR, 3.94; 95% CI, 2.00-7.76, respectively). These effects of haplotypes TCT and TGT on lung cancer risk were observed in three major histologic types of lung cancer. These results suggest that the VEGF gene may be contribute to an inherited predisposition to lung cancer. 相似文献
84.
85.
Abrupt visual loss during anti-vascular endothelial growth factor treatment for type 3 neovascularization 下载免费PDF全文
AIM: To investigate the incidence of abrupt visual loss and its associated factors, during anti-vascular endothelial growth factor (VEGF) treatment for type 3 neovascularization.
METHODS: This retrospective study included 137 eyes that were newly diagnosed with type 3 neovascularization. All eyes were treated with anti-VEGF therapy. Abrupt visual loss was defined as loss of 5 or more lines in best-corrected visual acuity (BCVA) in comparison to the previous visit. The incidence and timing of abrupt visual loss as well as the factors associated with it, were determined. In addition, the BCVA at the final follow-up was compared between the eyes with and those without abrupt visual loss.
RESULTS: The mean follow-up period was 42.4±18.9mo after diagnosis, and abrupt visual loss was noted in 22 eyes (16.1%) at a mean of 19.6±13.9mo. Abrupt visual loss was found to be associated with subretinal hemorrhage in 11 eyes (50.0%), development of or increase in the height of pigment epithelial detachment with fluid in 8 eyes (36.4%), and tears in the retinal pigment epithelium in 3 eyes (13.6%). The logarithm of minimum angle of resolution (logMAR) mean BCVA at the final follow-up was 2.07±0.67 (Snellen equivalents: 20/2349) and 1.00±0.55 (20/200) in eyes with and without abrupt visual loss, respectively. BCVA was significantly worse in the eyes with abrupt visual loss (P<0.001).
CONCLUSION: Abrupt visual loss is noted in 16.1% of patients with type 3 neovascularization and is associated with poor visual outcome. Additional studies are needed to determine how abrupt visual loss can be prevented. 相似文献
86.
87.
Seung-Jin Park Yea Eun Kang Jeong-Hwan Kim Jong-Lyul Park Seon-Kyu Kim Seung-Woo Baek In Sun Chu Shinae Yi Seong Eun Lee Young Joo Park Eun-Jae Chung Jin Man Kim Hye Mi Ko Je-Ryong Kim Seung-Nam Jung Ho-Ryun Won Jae Won Chang Bon Seok Koo Seon-Young Kim 《Clinical and experimental otorhinolaryngology》2022,15(2):183
88.
Comparative toxicity of silicon dioxide,silver and iron oxide nanoparticles after repeated oral administration to rats 下载免费PDF全文
Jun‐Won Yun Seung‐Hyun Kim Ji‐Ran You Woo Ho Kim Ja‐June Jang Seung‐Kee Min Hee Chan Kim Doo Hyun Chung Jayoung Jeong Byeong‐Cheol Kang Jeong‐Hwan Che 《Journal of applied toxicology : JAT》2015,35(6):681-693
Although silicon dioxide (SiO2), silver (Ag) and iron oxide (Fe2O3) nanoparticles are widely used in diverse applications from food to biomedicine, in vivo toxicities of these nanoparticles exposed via the oral route remain highly controversial. To examine the systemic toxicity of these nanoparticles, well‐dispersed nanoparticles were orally administered to Sprague–Dawley rats daily over a 13‐week period. Based on the results of an acute toxicity and a 14‐day repeated toxicity study, 975.9, 1030.5 and 1000 mg kg–1 were selected as the highest dose of the SiO2, Ag and Fe2O3 nanoparticles, respectively, for the 13‐week repeated oral toxicity study. The SiO2 and Fe2O3 nanoparticles did not induce dose‐related changes in a number of parameters associated with the systemic toxicity up to 975.9 and 1000 mg kg–1, respectively, whereas the Ag nanoparticles resulted in increases in serum alkaline phosphatase and calcium as well as lymphocyte infiltration in liver and kidney, raising the possibility of liver and kidney toxicity induced by the Ag nanoparticles. Compared with the SiO2 and Fe2O3 nanoparticles showing no systemic distribution in all tissues tested, the Ag concentration in sampled blood and organs in the Ag nanoparticle‐treated group significantly increased with a positive and/or dose‐related trend, meaning that the systemic toxicity of the Ag nanoparticles, including liver and kidney toxicity, might be explained by extensive systemic distribution of Ag originating from the Ag nanoparticles. Our current results suggest that further study is required to identify that Ag detected outside the gastrointestinal tract were indeed a nanoparticle form or ionized form. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
89.
Incorporation of high‐dose 131I‐metaiodobenzylguanidine treatment into killer immunoglobulin‐like receptor/HLA‐ligand mismatched haploidentical stem cell transplantation for children with neuroblastoma who failed tandem autologous stem cell transplantation 下载免费PDF全文
90.