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   651篇
  免费   33篇
  国内免费   2篇
耳鼻咽喉   9篇
儿科学   10篇
妇产科学   22篇
基础医学   67篇
口腔科学   30篇
临床医学   77篇
内科学   132篇
皮肤病学   6篇
神经病学   41篇
特种医学   24篇
外科学   61篇
综合类   12篇
一般理论   2篇
预防医学   34篇
眼科学   53篇
药学   78篇
中国医学   5篇
肿瘤学   23篇
  2024年   2篇
  2023年   7篇
  2022年   17篇
  2021年   43篇
  2020年   26篇
  2019年   29篇
  2018年   49篇
  2017年   24篇
  2016年   30篇
  2015年   31篇
  2014年   42篇
  2013年   44篇
  2012年   48篇
  2011年   66篇
  2010年   39篇
  2009年   27篇
  2008年   51篇
  2007年   51篇
  2006年   27篇
  2005年   10篇
  2004年   7篇
  2003年   4篇
  2002年   2篇
  2000年   2篇
  1997年   1篇
  1996年   1篇
  1995年   1篇
  1985年   1篇
  1978年   1篇
  1975年   2篇
  1969年   1篇
排序方式: 共有686条查询结果,搜索用时 296 毫秒
1.
2.
Portilla-Fernández  Eliana  Hwang  Shih-Jen  Wilson  Rory  Maddock  Jane  Hill  W. David  Teumer  Alexander  Mishra  Pashupati P.  Brody  Jennifer A.  Joehanes  Roby  Ligthart  Symen  Ghanbari  Mohsen  Kavousi  Maryam  Roks  Anton J. M.  Danser  A. H. Jan  Levy  Daniel  Peters  Annette  Ghasemi  Sahar  Schminke  Ulf  Dörr  Marcus  Grabe  Hans J.  Lehtimäki  Terho  Kähönen  Mika  Hurme  Mikko A.  Bartz  Traci M.  Sotoodehnia  Nona  Bis  Joshua C.  Thiery  Joachim  Koenig  Wolfgang  Ong  Ken K.  Bell  Jordana T.  Meisinger  Christine  Wardlaw  Joanna M.  Starr  John M.  Seissler  Jochen  Then  Cornelia  Rathmann  Wolfgang  Ikram  M. Arfan  Psaty  Bruce M.  Raitakari  Olli T.  Völzke  Henry  Deary  Ian J.  Wong  Andrew  Waldenberger  Melanie  O’Donnell  Christopher J.  Dehghan  Abbas 《European journal of epidemiology》2021,36(11):1143-1155

Common carotid intima-media thickness (cIMT) is an index of subclinical atherosclerosis that is associated with ischemic stroke and coronary artery disease (CAD). We undertook a cross-sectional epigenome-wide association study (EWAS) of measures of cIMT in 6400 individuals. Mendelian randomization analysis was applied to investigate the potential causal role of DNA methylation in the link between atherosclerotic cardiovascular risk factors and cIMT or clinical cardiovascular disease. The CpG site cg05575921 was associated with cIMT (beta?=??0.0264, p value?=?3.5?×?10–8) in the discovery panel and was replicated in replication panel (beta?=??0.07, p value?=?0.005). This CpG is located at chr5:81649347 in the intron 3 of the aryl hydrocarbon receptor repressor gene (AHRR). Our results indicate that DNA methylation at cg05575921 might be in the pathway between smoking, cIMT and stroke. Moreover, in a region-based analysis, 34 differentially methylated regions (DMRs) were identified of which a DMR upstream of ALOX12 showed the strongest association with cIMT (p value?=?1.4?×?10–13). In conclusion, our study suggests that DNA methylation may play a role in the link between cardiovascular risk factors, cIMT and clinical cardiovascular disease.

  相似文献   
3.
Background: Tobacco use is a significant predisposing factor to many diseases. Protection motivation theory is a well-suited theory, since fear can motivate individuals to change their unhealthy behaviors. Objective: This study was conducted to examine the associations between the constructs of this theory with intention and tobacco use behavior. Method: The present cross-sectional study was conducted in Noshahr, Iran. The participants were 440 high school boys selected using a stratified random sampling in 2016. A questionnaire about tobacco use based on protection motivation theory was developed and its validity and reliability were assessed. The questionnaire included the demographic information, the constructs of theory, and tobacco use behavior. Structural equation modeling was used to test the associations between the constructs with intention and tobacco use. Results: The variables of perceived vulnerability (β = 0/137, P < 0.001), fear (β = 0/149, P < 0.001), self-efficacy (β = 0/249, P < 0.001), perceived intrinsic reward (β = ?0.285, P < 0.001), threat appraisal (β = ?0.25, P < 0.001), and coping appraisal (β = 0.358, P < 0.001) had direct effect and are significant with intention. Moreover, perceived vulnerability (β = ?0.158, P < 0.001), fear (β = ?0.172, P < 0.001), self-efficacy (β = ?0.288, P < 0.001), perceived intrinsic reward (β = 0.329, P < 0.001), threat appraisal (β = 0.265, P < 0.001), and coping appraisal (β = ?0.379, P < 0.001) affected tobacco use indirectly through intention and were significantly associated with behavior. Also, intention had direct effect and is significant with tobacco use (β = ?1.156, P < 0.001). Conclusions: The protection motivation theory provides a useful framework for investigating factors of tobacco use among male students. Future tobacco prevention interventions should focus on increasing the vulnerability and fear, decreasing intrinsic reward, and improving self-efficacy to reduce tobacco use.  相似文献   
4.
5.
This paper provides significant ethnobotanical information on pharmaceutical plant uses, where some degree of acculturation exists, so that there is urgency in recording such data. The aim of this work is to catalogue, document, and make known the uses of plants for folk medicine in Dehloran and Abdanan districts, Ilam Province, Iran. An analysis was made of the species used, parts of the plant employed, preparation methods, administration means, and the ailments treated in relation to pathological groups. A folk botanical survey was carried out from February 2007 to October 2009. The information was collected from 81 persons (60% men and 40% women) in 20 villages. The informants reported data on 122 species, belonging to 49 botanical families, were claimed as medicinal. This work is focused on human medicinal plant uses, which represent 95% of the pharmaceutical uses. The most commonly represented families were Asteraceae (37.5%), Lamiaceae (20.8%), Rosaceae (18.7%), Fabaceae (16.7%) and Apiaceae (14.6%). Some of the uses were found to be new when compared with published literature on ethnomedicine of Iran. The folk knowledge about medicinal plant use is still alive in the studied region, and a number of scarcely reported plant uses has been detected, some of them with promising phytotherapeutical applications. The results of the study reveal that some of species play an important role in primary healthcare system of these tribal communities.  相似文献   
6.
7.
In this work we proposed a model for in vitro interaction of fenitrothion (FEN) with calf thymus-DNA by combination of multispectroscopic and two dimensional molecular modeling (ONIOM) methods. The circular dichroism results showed that FEN changes the conformation of B-DNA and caused some changes to C-DNA form. The FT-IR results confirmed a partial intercalation between FEN and edges of all base pairs. The competitive fluorescence, using methylene blue as fluorescence probe, in the presence of increasing amounts of FEN, revealed that FEN is able to release the non-intercalated methylene blue from the DNA. The weak chemical shift and peak broadening of 1H NMR spectrum of FEN in the presence of DNA confirmed a non-intercalation mode. The 31P NMR showed that FEN interacts more with DNA via its –NO2 moiety. The ONIOM, based on the hybridization of QM/MM (DFT, 6.31++G (d,p)/UFF) methodology, was also performed by Gaussian 2003 package. The results revealed that the interaction is base sequence dependent, and FEN interacts more with AT base sequences.  相似文献   
8.
Vitrectomy and endoresection is an alternative to enucleation for the treatment of large malignant choroidal melanoma. We report a rare case of extensive recurrence of choroidal malignant melanoma with extraocular extension 11 years after surgical endoresection without adjuvant treatment.  相似文献   
9.
Indoleamine 2,3-dioxygenase (IDO), an enzyme responsible for tryptophan catabolism, is thought to be required to prevent the rejection of the allogenic fetus by maternal T cells and to protect against intra- and extra-cellular pathogens. Consequently, we studied the expression of IDO in the endometrium of female Balb/c mice during the oestrous cycle. At each phase, the endometrium was peeled away and the relative expression of IDO mRNA was detected by semi-quantitative RT-PCR. The presence of IDO protein was confirmed in each phase by Western blotting and immunohistochemistry. Our results showed that IDO is expressed in the endometrium of cycling mice during all the phases of oestrous cycle. The expression of IDO was highest at the oestrus and lowest at the dioestrus. By means of Western blotting and immunohistochemistry, we obtained evidence that IDO protein is synthesised in the endometrium of cycling mice throughout the oestrous cycle. In accordance with RT-PCR results, IDO protein was predominant at the oestrus phase. IDO protein was mainly localised in the glandular and luminal epithelial cells. Our results support the concept of IDO providing a mechanism of innate immunity to protect from ascending infections of the female reproductive tract. In addition, considering the fact that mating only occurs during the oestrus phase, the high expression of IDO in this phase is likely to be a mechanism that induces immunological tolerance of the fetus.  相似文献   
10.

Introduction

REM sleep deprivation (SD) decreases tolerance of the rat heart to ischemia-reperfusion (IR) injury; the underlying mechanisms, however, are unknown. This study aimed at determining whether changes in iNOS, Bax, and Bcl-2 gene expression are involved in this detrimental effect.

Method

SD was induced by flowerpot technique for a period of 4 days. This method is simple and able to induce sleep fragmentation which occurs as one of the sleep disorder symptoms in clinical conditions. The hearts of control and SD rats were perfused in Langendorff apparatus and subjected to 30 min ischemia, followed by 90 min reperfusion. The hemodynamic parameters (left ventricular developed pressure (LVDP), and ± dp/dt), NOx (nitrite + nitrate) level, infarct size, and mRNA expression of iNOS, Bax, and Bcl-2 were measured after IR.

Results

SD rats had lower recovery of post-ischemic LVDP (32.8 ± 2.5 vs. 51.5 ± 2.1 mmHg; P < 0.05), + dp/dt (1555 ± 66 vs. 1119.5 ± 87 mmHg/s; P < 0.05) and ? dp/dt (1437 ± 65 vs. 888 ± 162 mmHg/s; P < 0.05). SD rats also had higher NOx levels (41.4 ± 3.1 vs. 22.4 ± 3.6 μmol/L; P < 0.05) and infarct size (64.3 ± 2.3 vs. 38.3 ± 1.6%; P < 0.05) after IR, which along with LVDP, ± dp/dt restored to near normal status in the presence of aminoguanidine, a selective iNOS inhibitor. Following IR, expression of iNOS and Bax increased and Bcl-2 decreased (502, 372, and 54%, respectively) in SD rats; whereas in the presence of aminoguanidine, expression of iNOS and Bax significantly decreased and Bcl-2 increased (165, 168, and 19%, respectively).

Conclusion

Higher expression of iNOS and subsequent increase in apoptosis in the hearts after IR may contribute to less tolerance to myocardial IR injury in SD rats.
  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