全文获取类型
收费全文 | 2707篇 |
免费 | 159篇 |
国内免费 | 24篇 |
专业分类
耳鼻咽喉 | 30篇 |
儿科学 | 58篇 |
妇产科学 | 17篇 |
基础医学 | 331篇 |
口腔科学 | 39篇 |
临床医学 | 175篇 |
内科学 | 772篇 |
皮肤病学 | 53篇 |
神经病学 | 206篇 |
特种医学 | 165篇 |
外科学 | 486篇 |
综合类 | 22篇 |
预防医学 | 76篇 |
眼科学 | 14篇 |
药学 | 128篇 |
中国医学 | 18篇 |
肿瘤学 | 300篇 |
出版年
2023年 | 14篇 |
2022年 | 62篇 |
2021年 | 84篇 |
2020年 | 61篇 |
2019年 | 82篇 |
2018年 | 92篇 |
2017年 | 68篇 |
2016年 | 68篇 |
2015年 | 67篇 |
2014年 | 110篇 |
2013年 | 132篇 |
2012年 | 202篇 |
2011年 | 218篇 |
2010年 | 146篇 |
2009年 | 116篇 |
2008年 | 168篇 |
2007年 | 186篇 |
2006年 | 183篇 |
2005年 | 161篇 |
2004年 | 130篇 |
2003年 | 155篇 |
2002年 | 128篇 |
2001年 | 18篇 |
2000年 | 19篇 |
1999年 | 18篇 |
1998年 | 22篇 |
1997年 | 28篇 |
1996年 | 15篇 |
1995年 | 22篇 |
1994年 | 14篇 |
1993年 | 12篇 |
1992年 | 13篇 |
1991年 | 5篇 |
1990年 | 4篇 |
1989年 | 8篇 |
1986年 | 2篇 |
1985年 | 2篇 |
1984年 | 5篇 |
1983年 | 3篇 |
1982年 | 5篇 |
1981年 | 5篇 |
1980年 | 5篇 |
1978年 | 4篇 |
1977年 | 2篇 |
1976年 | 3篇 |
1975年 | 2篇 |
1974年 | 2篇 |
1968年 | 2篇 |
1963年 | 2篇 |
1929年 | 2篇 |
排序方式: 共有2890条查询结果,搜索用时 31 毫秒
61.
Shunsuke Koseki Takamasa Noda Satoshi Yokoyama Yoshihiko Kunisato Daisuke Ito Haruna Suyama Taro Matsuda Yuji Sugimura Naoko Ishihara Yu Shimizu Kanako Nakazawa Sumiko Yoshida Kunimasa Arima Shin-ichi Suzuki 《Journal of affective disorders》2013
Background
Recently, neurobiological studies of the cognitive model of depression have become vastly more important, and a growing number of such studies are being reported. However, the relationship between the proportion of positive and negative automatic thought and activity in the prefrontal and temporal cortices has not yet been explored. We examined the relationship between brain activity and the proportion of positive and negative automatic thought in patients with major depressive disorder (MDD), using multi-channel near-infrared spectroscopy (NIRS).Methods
We recruited 75 individuals with MDD (36 females; mean age=39.23±12.49). They completed the Hamilton Rating Scale for Depression, Automatic Thoughts Questionnaire-Revised, Japanese version of the National Adult Reading Test, and the State-Trait Anxiety Inventory. Brain activation was measured by 52-channel NIRS.Results
We found that activation in the vicinity of the right superior temporal gyrus is related to a deviation to negative of the proportion of positive and negative thoughts in individuals with MDD. Left dorsolateral prefrontal cortex activity was higher in the group with comparatively frequent positive thought.Limitations
Our participants were patients taking antidepressant medication, which is known to influence brain activity. Second, the poor spatial resolution of NIRS increases the difficulty of identifying the measurement position.Conclusions
We found that activation of the prefrontal and temporal cortices is related to the proportion of automatic thoughts in the cognitive model of depression. 相似文献62.
Objectives: The study aimed to (1) elucidate the energetic adaptations of Huli people by comparing the three sub-populations in relation to their diversified natural and socioeconomic environment, based on energy expenditure and time allocation data; and (2) assess the applicability of a new index of physical exertion levels of activities (physical exertion index: PEI). Research design and methods: Married males and females (n = 43) were selected, including 14 from a hilly village, 13 from a flat swampy village and 16 migrants to a town. Continuous heart rate (HR) monitoring, in conjunction with minute-by-minute observation of activities, was undertaken. Total energy expenditure was assessed by flex-HR method and physical activity level (PAL) was calculated as multiples of basal metabolic rate. Observed activities were divided into 15 categories and the PEI was calculated for each: PEI= (mean HR of a categorized activity)/(flex HR) x 100. Results : No significant difference was found in PAL among the three sub-populations: 1.77, 1.92 and 1.81 for men and 1.78, 1.98 and 1.66 for women in hilly and flat villages, and a town, respectively. The comparison of the two village groups revealed that hilly terrain did not affect substantially the physical intensity of agricultural activities. On the other hand, the town migrants were engaged in sedentary paid jobs and these were less energy consuming than agricultural work. However, the different energy costs between paid jobs and agricultural work were offset by longer work time in the town group than in the two village groups (251 vs 50 or 70 min in males; 258 vs 152 or 138 min in females), resulting in similar PAL in the three groups. Conclusions: Despite contrasting natural and social environments, no significant difference was found in daily physical activity level among the three sub-populations (two villages and a town) of Huli-speaking people in Papua New Guinea Highlands. 相似文献
63.
Irona Khandaker Akira Suzuki Taro Kamigaki Kentaro Tohma Takashi Odagiri Takashi Okada Ayumu Ohno Kanako Otani Rumi Sawayama Kazuhisa Kawamura Michiko Okamoto Hitoshi Oshitani 《Virus genes》2013,47(3):456-466
Analyzing the evolutionary pattern of the influenza A(H1N1)pdm09 strain in different regions is important for understanding its diversification. We therefore conducted this study to elucidate the genetic variability and molecular evolution of the influenza A(H1N1)pdm09 strains that circulated during the 2009–2010 and 2010–2011 influenza seasons in Sendai, Japan. Nasopharyngeal swab specimens were collected from patients with influenza-like illnesses who visited outpatient clinics in Sendai City, Japan, from September 2009 to April 2011. A total of 75 isolates were selected from September 2009 to April 2011 to analyze the genetic changes in the entire hemagglutinin 1 (HA1) segment of the HA gene and the neuraminidase (NA) gene based on sequence analysis. Bayesian coalescent Markov chain Monte Carlo analyses of HA1 and NA gene sequences were performed for further analysis. High sequence identities were observed for HA1 and NA in influenza A(H1N1)pdm09, displaying 99.06 and 99.33 % nucleotide identities, respectively, with the A(H1N1)pdm09 vaccine strain A/California/07/2009. The substitution rates of nucleotides for HA1 in the 2009–2010 and 2010–2011 were 1.5 × 10?3 and 1.6 × 10?3 substitutions per site per year, respectively. Phylogenetic tree analysis demonstrated that Sendai isolates were clustered into global clade 7, which is characterized by an S203T mutation in the HA1 gene. Moreover, two distinct circulation clusters were present in the 2010–2011 season. Mutations were present in antigenic or receptor-binding domains of the HA1 segment, including A141V, S143G, S183P, S185T, and S203T. The Bayesian skyline plot model illustrated a steady rate for the maintenance of genetic diversity, followed by a slight increase in the later part of the 2010–2011 season. Selection analysis revealed that the HA1 (position 197) and NA (position 46) sites were under positive selection; however, no known mutation conferring resistance to NA inhibitors such as H275Y was observed. The effect on control of the influenza A(H1N1)pdm09 virus, including vaccine strain selection, requires continuous monitoring of the strain by genetic surveillance. 相似文献
64.
Wu Nan Huang Zhe Shen Yiqiu Park Jungkyu Phang Jason Makino Taro Gene Kim S. Cho Kyunghyun Heacock Laura Moy Linda Geras Krzysztof J. 《Journal of digital imaging》2021,34(6):1414-1423
Journal of Digital Imaging - Breast cancer is the most common cancer in women, and hundreds of thousands of unnecessary biopsies are done around the world at a tremendous cost. It is crucial to... 相似文献
65.
Isabella Wimmer Cornelia Scharler Taro Kadowaki Sophie Hillebrand Barbara ScheiberMojdehkar Shuichi Ueda Monika Bradl Thomas Berger Hans Lassmann Simon Hametner 《Brain pathology (Zurich, Switzerland)》2021,31(2):333
Iron accumulation in the CNS is associated with many neurological diseases via amplification of inflammation and neurodegeneration. However, experimental studies on iron overload are challenging, since rodents hardly accumulate brain iron in contrast to humans. Here, we studied LEWzizi rats, which present with elevated CNS iron loads, aiming to characterise choroid plexus, ependymal, CSF and CNS parenchymal iron loads in conjunction with altered blood iron parameters and, thus, signifying non‐classical entry sites for iron into the CNS. Non‐haem iron in formalin‐fixed paraffin‐embedded tissue was detected via DAB‐enhanced Turnbull Blue stainings. CSF iron levels were determined via atomic absorption spectroscopy. Ferroportin and aquaporin‐1 expression was visualised using immunohistochemistry. The analysis of red blood cell indices and serum/plasma parameters was based on automated measurements; the fragility of red blood cells was manually determined by the osmotic challenge. Compared with wild‐type animals, LEWzizi rats showed strongly increased iron accumulation in choroid plexus epithelial cells as well as in ependymal cells of the ventricle lining. Concurrently, red blood cell macrocytosis, low‐grade haemolysis and significant haemoglobin liberation from red blood cells were apparent in the peripheral blood of LEWzizi rats. Interestingly, elevated iron accumulation was also evident in kidney proximal tubules, which share similarities with the blood–CSF barrier. Our data underscore the importance of iron gateways into the CNS other than the classical route across microvessels in the CNS parenchyma. Our findings of pronounced choroid plexus iron overload in conjunction with peripheral iron overload and increased RBC fragility in LEWzizi rats may be seminal for future studies of human diseases, in which similar constellations are found. 相似文献
66.
67.
Takahiro Fuchigami Yutaka Sato Yuya Tomita Tetsuya Takano Shin‐ya Miyauchi Yukinori Tsuchiya Taro Saito Ken‐ichiro Kubo Kazunori Nakajima Mitsunori Fukuda Mitsuharu Hattori Shin‐ichi Hisanaga 《Genes to cells : devoted to molecular & cellular mechanisms》2013,18(5):410-424
Reelin‐Dab1 signaling is indispensable for proper positioning of neurons in mammalian brain. Reelin is a glycoprotein secreted from Cajal‐Reztuis cells in marginal zone of cerebral cortex, and its receptors are Apolipoprotein E receptor 2 (ApoER2) or very low density lipoprotein receptor (VLDLR) expressed on migrating neurons. When Reelin binds to ApoER2 or VLDLR, an adaptor protein Dab1 bound to the receptors undergoes Tyr phosphorylation that is essential for Reelin signaling. We reported previously that Cdk5‐p35 phosphorylates Dab1 at Ser400 and Ser491 and the phosphorylation regulates its binding to CIN85, which is an SH3‐containing multiadaptor protein involved in endocytic downregulation of receptor‐tyrosine kinases. However, the interaction of CIN85 with Dab1 has not been addressed in neurons. We examined here a possibility that CIN85 has a role in Reelin signaling. We found nonpho‐sphorylated Dab1‐mediated colocalization of CIN85 with ApoER2. The colocalization of CIN85 with ApoER2 was increased in neurons stimulated with Reelin repeats 3‐6, an active Reelin fragment. The stimulation recruited CIN85 to domains in plasma membrane where it colocalized with ApoER2 and Dab1 and then to EEA1‐labeled early endosomes in the cytoplasm. In addition, Tyr phosphorylation of Dab1 strengthened the binding to CIN85. These results suggest that CIN85 participates in Reelin signaling through the binding to Dab1. 相似文献
68.
69.
70.