首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   1885篇
  免费   128篇
  国内免费   13篇
耳鼻咽喉   7篇
儿科学   41篇
妇产科学   41篇
基础医学   320篇
口腔科学   66篇
临床医学   227篇
内科学   347篇
皮肤病学   25篇
神经病学   184篇
特种医学   116篇
外科学   146篇
综合类   13篇
预防医学   182篇
眼科学   22篇
药学   183篇
中国医学   9篇
肿瘤学   97篇
  2024年   1篇
  2023年   27篇
  2022年   59篇
  2021年   96篇
  2020年   62篇
  2019年   75篇
  2018年   100篇
  2017年   56篇
  2016年   74篇
  2015年   79篇
  2014年   108篇
  2013年   155篇
  2012年   180篇
  2011年   190篇
  2010年   101篇
  2009年   71篇
  2008年   103篇
  2007年   103篇
  2006年   102篇
  2005年   78篇
  2004年   58篇
  2003年   41篇
  2002年   34篇
  2001年   6篇
  2000年   6篇
  1999年   4篇
  1998年   7篇
  1997年   5篇
  1996年   7篇
  1995年   4篇
  1994年   1篇
  1993年   3篇
  1992年   4篇
  1991年   1篇
  1990年   1篇
  1988年   3篇
  1986年   3篇
  1985年   1篇
  1984年   5篇
  1983年   1篇
  1982年   2篇
  1981年   1篇
  1980年   1篇
  1978年   2篇
  1973年   1篇
  1956年   2篇
  1954年   2篇
排序方式: 共有2026条查询结果,搜索用时 31 毫秒
21.
Cuprizone [bis(cyclohexylidenehydrazide)]-induced toxic demyelination is an experimental animal model commonly used to study de- and remyelination in the central nervous system. In this model, mice are fed with the copper chelator cuprizone which leads to oligodendrocyte death with subsequent demyelination. The underlying mechanisms of cuprizone-induced oligodendrocyte death are still unknown, and appropriate in vitro investigations to study these mechanisms are not available. Thus, we studied cuprizone effects on rat primary glial cell cultures and on the neuroblastoma cell line SH-SY5Y. Treatment of cells with different concentrations of cuprizone failed to show effects on the proliferation and survival of SH-SY5Y cells, microglia, astrocytes, and oligodendrocyte precursor cells (OPC). In contrast, differentiated mature oligodendrocytes (OL) were found to be significantly affected by cuprizone treatment. This was accompanied by a reduced mitochondrial potential in cuprizone-treated OL. These results demonstrate that the main toxic target for cuprizone is mature OL, whilst other glial cells including OPC are not or only marginally affected. This explains the selective demyelination induced by cuprizone in vivo.  相似文献   
22.
23.
24.
25.
The actual nature of spindle cell carcinoma has been debated extensively because of its rarity. It carries a poor prognosis, even when early-stage disease is diagnosed and resected. In view of the rarity and the significance of the histological diagnosis, we report a patient with rapidly progressing spindle cell lung carcinoma with soft tissue metastasis. Diagnosis was confirmed by immunohistochemistry finding. Analysis of the TP53 gene mutations by polymerase chain reaction and DNA sequencing revealed insertion of single thymine resulting in frameshift mutation in the exon 8. Prognosis of spindle cell lung carcinoma might be determined by the sarcoma component of the tumor and, based on that, we wonder if this type of lung carcinoma could be followed-up and treated by strategies for soft tissue sarcomas, because of its rapid, sarcomatous type of growth, beside the properly lung carcinoma oncological treatment.  相似文献   
26.
27.

Aims/hypothesis

The self-administered Michigan Neuropathy Screening Instrument (MNSI) is used to diagnose diabetic peripheral neuropathy. We examined whether the MNSI might also provide information on risk of death and cardiovascular outcomes.

Methods

In this post hoc analysis of the Aliskiren Trial in Type 2 Diabetes Using Cardio-Renal Endpoints (ALTITUDE) trial, we divided 8463 participants with type 2 diabetes and chronic kidney disease (CKD) and/or cardiovascular disease (CVD) into independent training (n = 3252) and validation (n = 5211) sets. In the training set, we identified specific questions that were independently associated with a cardiovascular composite outcome (cardiovascular death, resuscitated cardiac arrest, non-fatal myocardial infarction/stroke, heart failure hospitalisation). We then evaluated the performance of these questions in the validation set.

Results

In the training set, three questions (‘Are your legs numb?’, ‘Have you ever had an open sore on your foot?’ and ‘Do your legs hurt when you walk?’) were significantly associated with the cardiovascular composite outcome. In the validation set, after multivariable adjustment for key covariates, one or more positive responses (n = 3079, 59.1%) was associated with a higher risk of the cardiovascular composite outcome (HR 1.54 [95% CI 1.28, 1.85], p < 0.001), heart failure hospitalisation (HR 1.74 [95% CI 1.29, 2.35], p < 0.001), myocardial infarction (HR 1.81 [95% CI 1.23, 2.69], p = 0.003), stroke (HR 1.75 [95% CI 1.20, 2.56], p = 0.003) and three-point major adverse cardiovascular events (MACE) (cardiovascular death, non-fatal myocardial infarction, non-fatal stroke) (HR 1.49 [95% CI 1.20, 1.85], p < 0.001) relative to no positive responses to all questions. Associations were stronger if participants answered positively to all three questions (n = 552, 11%). The addition of the total number of affirmative responses to existing models significantly improved Harrell’s C statistic for the cardiovascular composite outcome (0.70 vs 0.71, p = 0.010), continuous net reclassification improvement (+22% [+10%, +31%], p = 0.027) and integrated discrimination improvement (+0.9% [+0.4%, +2.1%], p = 0.007).

Conclusions/interpretation

We identified three questions from the MNSI that provide additional prognostic information for individuals with type 2 diabetes and CKD and/or CVD. If externally validated, these questions may be integrated into the clinical history to augment prediction of CV events in high-risk individuals with type 2 diabetes.
  相似文献   
28.
Purpose: The purpose of this study was to investigate in vivo antitumor activity of newly synthesized N-sulfonylpyrimidine derivatives 1-(p-toluenesulfonyl)cytosine (4H), 1-(p-toluenesulfonyl)cytosine hydrochloride (4H×HCl) and zinc(II) complex of 1-(p-toluenesulfonyl)cytosine (4K). Materials and methods: In order to do that we have used mouse anaplastic mammary carcinoma (AMCa). Tumor cells (106) in a volume of 0.02 ml were transplanted into the thigh of the right hind leg of CBA mice. All compounds were dissolved in distilled water immediately before injecting to animals. Results: Antitumor effect of these compounds depends on drug doses and time interval between tumor transplantation and drug application. Further the efficacy of these compounds depends on number of drug injections, i. e. whether drug was given in single or in multiple doses. Multiple doses of 400 mg/kg of 1-(p-toluenesulfonyl)cytosine (4H) showed good antitumor effect when applied on day 1, 3, 5, 7 and 9 after tumor transplantation. Still good but slightly lower antitumor effect was also achieved when that compound was given in a single dose (1,200 mg/kg) on day 1 after tumor transplantation. The longest period of tumor growth time was obtained after application of 1-(p-toluenesulfonyl)cytosine hydrochloride (4H×HCl) given as a single dose (300 mg/kg) on day 1 or on day 6 after tumor implantation. However, antitumor effect of zinc(II) complex of 1-(p-toluenesulfonyl)cytosine (4K) was very strong when 300 mg/kg was given on day 1 or day 6, while this effect was slightly lower when drug (200 mg/kg/inj) was given on day 1, 3, 5, 7 and 9 or on day 6, 8, 10, 12 and 14. Conclusion: In this work it has been found that N-1-sulfonylcytosine derivatives have strong antitumor activity against mouse mammary carcinoma which is a good reason for further research of these compounds both in experimental and preclinical studies.  相似文献   
29.
30.
Migraine shares a complex and poorly understood relationship with sleep. Patients consistently report poor sleep prior to migraine attacks and during them, identifying poor sleep as a migraine trigger. However, anecdotally, sleep is reported to serve a therapeutic role in terminating headache. Are the associations between migraine and sleep simply the result of various bidirectional relationships? A growing body of evidence suggests there may be a common underlying etiology as well. Our objective was to review studies of sleep and migraine from the last 2 decades utilizing validated subjective and objective measures of sleep and to explore potential mechanisms underlying this complex relationship by incorporating recent advances in neuroscience. We specifically focus on insomnia, obstructive sleep apnea, parasomnias, sleep related movement disorders, and REM sleep related disorders and their relationship to migraine. Parts of brainstem‐cortical networks involved in sleep physiology are unintentionally being identified as important factors in the common migraine pathway. Recent discoveries on anatomic localization (the hypothalamus as a key and early mediator in the pathophysiology of migraine), common mediating signaling molecules (such as serotonin and dopamine), and the discovery of a new CNS waste removal system, the glymphatic system, all point to a common pathophysiology manifesting in migraine and sleep problems.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号