全文获取类型
收费全文 | 867篇 |
免费 | 44篇 |
国内免费 | 26篇 |
专业分类
耳鼻咽喉 | 8篇 |
儿科学 | 22篇 |
妇产科学 | 7篇 |
基础医学 | 77篇 |
口腔科学 | 9篇 |
临床医学 | 94篇 |
内科学 | 178篇 |
皮肤病学 | 4篇 |
神经病学 | 56篇 |
特种医学 | 110篇 |
外科学 | 127篇 |
综合类 | 17篇 |
预防医学 | 102篇 |
眼科学 | 63篇 |
药学 | 44篇 |
肿瘤学 | 19篇 |
出版年
2022年 | 7篇 |
2021年 | 13篇 |
2020年 | 4篇 |
2019年 | 5篇 |
2018年 | 7篇 |
2017年 | 8篇 |
2016年 | 9篇 |
2015年 | 13篇 |
2014年 | 13篇 |
2013年 | 18篇 |
2012年 | 26篇 |
2011年 | 28篇 |
2010年 | 25篇 |
2009年 | 15篇 |
2008年 | 26篇 |
2007年 | 35篇 |
2006年 | 48篇 |
2005年 | 33篇 |
2004年 | 20篇 |
2003年 | 19篇 |
2002年 | 22篇 |
2001年 | 28篇 |
2000年 | 22篇 |
1999年 | 24篇 |
1998年 | 22篇 |
1997年 | 11篇 |
1996年 | 22篇 |
1995年 | 18篇 |
1994年 | 22篇 |
1993年 | 11篇 |
1992年 | 19篇 |
1991年 | 29篇 |
1990年 | 25篇 |
1989年 | 37篇 |
1988年 | 30篇 |
1987年 | 28篇 |
1986年 | 32篇 |
1985年 | 26篇 |
1984年 | 11篇 |
1983年 | 15篇 |
1982年 | 7篇 |
1981年 | 9篇 |
1980年 | 8篇 |
1979年 | 9篇 |
1978年 | 13篇 |
1977年 | 8篇 |
1976年 | 5篇 |
1975年 | 10篇 |
1972年 | 6篇 |
1971年 | 4篇 |
排序方式: 共有937条查询结果,搜索用时 15 毫秒
1.
2.
Benyam Kinde Harrison W. Gabel Caitlin S. Gilbert Eric C. Griffith Michael E. Greenberg 《Proceedings of the National Academy of Sciences of the United States of America》2015,112(22):6800-6806
DNA methylation at CpG dinucleotides is an important epigenetic regulator common to virtually all mammalian cell types, but recent evidence indicates that during early postnatal development neuronal genomes also accumulate uniquely high levels of two alternative forms of methylation, non-CpG methylation and hydroxymethylation. Here we discuss the distinct landscape of DNA methylation in neurons, how it is established, and how it might affect the binding and function of protein readers of DNA methylation. We review studies of one critical reader of DNA methylation in the brain, the Rett syndrome protein methyl CpG-binding protein 2 (MeCP2), and discuss how differential binding affinity of MeCP2 for non-CpG and hydroxymethylation may affect the function of this methyl-binding protein in the nervous system. 相似文献
3.
A convenience sample of hospital workers, those receiving influenza vaccine and those not receiving vaccine, were asked to complete questionnaires delineating the occurrence of symptoms (e.g., fever, headache, extreme tiredness, dry cough, sore throat, runny nose, stuffy nose, muscle aches) and absenteeism in the 7-day period post-vaccination if vaccinated. Those unvaccinated completed the questionnaire in a self-selected 7 consecutive day period during the study conducted from November 2004 to February 2005. Those receiving either Fluzone or FluMist reported significantly fewer symptoms and related absenteeism than the unvaccinated group (p < .05). Administration of influenza vaccine did not result in higher rates of post-vaccination symptoms as compared to an unvaccinated group. Further, vaccinated employees did not experience higher absenteeism rates as a result of receiving either influenza vaccine. However, for those reporting absenteeism as a result of symptoms, mean absenteeism days were highest in the FluMist group (4.5 days) compared to the unvaccinated group (2.1 days) and the Fluzone group (1.9 days). 相似文献
4.
5.
6.
A greenstick intercondylar fracture of the distal humerus occurred in a 14-year-old boy. The minimal displacement and stability of the injury allowed early range of motion with healing in an anatomic position and restoration of the preinjury arc of motion. 相似文献
7.
Lymphatic vessels are important in draining excess fluid from the abdominal space and preventing ascites. In sheep, diaphragmatic lymph vessels draining the abdominal space run to the caudal mediastinal lymph node and efferent vessels from the node drain into veins in the neck. To estimate the lymph flow response to excess intraperitoneal fluid in sheep, we cannulated a caudal mediastinal node efferent lymphatic in 5 sheep. After the sheep recovered from the surgery, the lymph flow (QL) was 154 +/- 161 (SD) microliters/min and the lymph protein concentration (CL) was 3.7 +/- 9 g/dl. Lymph flow decreased linearly with increases in lymphatic outflow pressure greater than 6 cmH2O. From this linear QL vs. outflow pressure relationship, we estimated the effective pressure driving lymph flow as the outflow pressure at which QL = 0. At baseline, the driving pressure was 24.7 +/- 14.0 cmH2O. After we infused Ringers solution (10% body weight) into the abdominal space, QL increased significantly to 7.0 +/- 4.1 times baseline and CL decreased significantly to 0.7 +/- 0.6 g/dl. Although the abdominal pressure increased significantly from 10.6 +/- 2.8 cmH2O to 15.8 +/- 2.1 cmH2O, we found no increase in lymphatic driving pressure. 相似文献
8.
9.
Mirjam Gross-Jendroska Christina J Flaxel Steve D Schwartz Frank G Holz Fred W Fitzke Veit-Peter Gabel Alan C Bird 《Clinical & experimental ophthalmology》1998,26(4):311-317
Purpose: To flatten pigment epithelial detachments (PED) cue to age-related macular degeneration in an attempt to visualize the underlying choroidal neovascularization by fluorescein angiography (FA) and reveal a treatment target. Methods: Nine patients with PED received intravitreal gas injections via the pars plana and postured face down. Fluorescein angiograms were obtained before and after gas injection. In two patients, retinal scotopic sensitivity was also measured. Results: Eight patients demonstrated change in the shape and size of the PED following gas injection. Four patients showed a better delineation of underlying structures on FA. Three patients had focal laser treatment to the newly visible choroidal neovascular complex, but this was successful in only one patient with flattening of the PED. Conclusion: Pigment epithelial detachments can be modified by intravitreal gas injection in some patients, but this treatment did not have a major impact on overall outcome or management. 相似文献
10.
The synthesis of boron-containing 1,3,5-triazines and 1,2,4-triazines is described. Derivatives of 1,3,5-triazine containing the o-carborane cluster have been obtained by reacting the corresponding propargyl derivatives with B(10)H(14). Derivatives of 1,2,4-triazine containing the B(12)H(12)(2-) cluster have been obtained by nucleophilic substitution of ethylsulfone derivatives with B(12)H(11)SH(2-). They have been isolated in their ring-protonated form. Reaction of RNH(2)-B(8)H(11)NH-R with stericly demanding heterocycles failed, either for steric or for solubility reasons. 相似文献