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   6622篇
  免费   540篇
  国内免费   98篇
耳鼻咽喉   49篇
儿科学   134篇
妇产科学   95篇
基础医学   763篇
口腔科学   241篇
临床医学   406篇
内科学   1000篇
皮肤病学   44篇
神经病学   444篇
特种医学   232篇
外国民族医学   2篇
外科学   603篇
综合类   406篇
预防医学   861篇
眼科学   462篇
药学   983篇
  1篇
中国医学   185篇
肿瘤学   349篇
  2023年   81篇
  2022年   118篇
  2021年   285篇
  2020年   190篇
  2019年   273篇
  2018年   230篇
  2017年   226篇
  2016年   222篇
  2015年   214篇
  2014年   380篇
  2013年   610篇
  2012年   276篇
  2011年   354篇
  2010年   273篇
  2009年   293篇
  2008年   324篇
  2007年   303篇
  2006年   260篇
  2005年   219篇
  2004年   218篇
  2003年   178篇
  2002年   145篇
  2001年   105篇
  2000年   104篇
  1999年   96篇
  1998年   83篇
  1997年   81篇
  1996年   84篇
  1995年   90篇
  1994年   62篇
  1993年   84篇
  1992年   57篇
  1991年   47篇
  1990年   56篇
  1989年   53篇
  1988年   69篇
  1987年   55篇
  1986年   38篇
  1985年   65篇
  1984年   54篇
  1983年   42篇
  1982年   50篇
  1981年   49篇
  1980年   30篇
  1979年   38篇
  1978年   24篇
  1977年   15篇
  1976年   12篇
  1975年   12篇
  1974年   10篇
排序方式: 共有7260条查询结果,搜索用时 36 毫秒
1.
Concentrations of 18 metals and elements (MEs) in the gills, skin, muscle and liver of Carasobarbus luteus and Cyprinus carpio from the Atatürk Reservoir in Turkey were investigated. The results revealed that variations in the ME contents between fish species can be attributed to different diets. The highest contents of most MEs were recorded in the gills. Gender had no significant effect on the contents of most MEs in the tissues of fish species investigated. The relations between MEs in tissues and fish size were not clear and consistent. Health risk assessment methods indicated that consumption of the studied fish species is safe. It was estimated that daily consumption of 140 g of C. carpio or 170 g of C. luteus would not be expected to cause any health risks. Furthermore, it was found that fish species would provide significant benefits in terms of intake of essential MEs.  相似文献   
2.
A 25-year-old, emaciated man without medical treatment was found to have died suddenly at home by his mother. At autopsy, there were no injuries to his body, but significant circulatory insufficiency was observed. Electron microscopy revealed abnormal mitochondria in cells of the cardiac conduction system. The conduction system was filled with mitochondrial size abnormalities and mitochondrial cristae abnormalities. No notable abnormal findings were observed in other organs. Genetic examination of the blood revealed the mitochondrial pathogenetic variant m.3243A>G. Epileptic seizures, diabetic ketoacidosis, and hyperosmolar hyperglycemic state were unlikely to be the cause of sudden death. The cause of death was diagnosed as arrhythmia possibly induced by the failure of the cardiac conduction system due to mitochondrial disease. This is a rare case of sudden death caused by an accumulation of abnormal mitochondria in the cardiac conduction system.  相似文献   
3.
4.
Circulating tumor cells (CTCs) in the blood of cancer patients are of high clinical relevance. Since detection and isolation of CTCs often rely on cell dimensions, knowledge of their size is key. We analyzed the median CTC size in a large cohort of breast (BC), prostate (PC), colorectal (CRC), and bladder (BLC) cancer patients. Images of patient‐derived CTCs acquired on cartridges of the FDA‐cleared CellSearch® method were retrospectively collected and automatically re‐analyzed using the accept software package. The median CTC diameter (μm) was computed per tumor type. The size differences between the different tumor types and references (tumor cell lines and leukocytes) were nonparametrically tested. A total of 1962 CellSearch® cartridges containing 71 612 CTCs were included. In BC, the median computed diameter (CD) of patient‐derived CTCs was 12.4 μm vs 18.4 μm for cultured cell line cells. For PC, CDs were 10.3 μm for CTCs vs 20.7 μm for cultured cell line cells. CDs for CTCs of CRC and BLC were 7.5 μm and 8.6 μm, respectively. Finally, leukocytes were 9.4 μm. CTC size differed statistically significantly between the four tumor types and between CTCs and the reference data. CTC size differences between tumor types are striking and CTCs are smaller than cell line tumor cells, whose size is often used as reference when developing CTC analysis methods. Based on our data, we suggest that the size of CTCs matters and should be kept in mind when designing and optimizing size‐based isolation methods.

Abbreviations

ACCEPT
Automated CTC Classification, Enumeration, and PhenoTyping software
BC
breast cancer
BLC
bladder cancer
CD
computed diameter
CEL
cultured tumor cell (cell line)
CK
cytokeratin
CRC
colorectal cancer
CTC‐L
circulating tumor cells derived from cerebrospinal fluid (liquor)
CTCs
circulating tumor cells
DAPI
4′6‐diamidino‐2‐phenylindole
EMT
epithelial–mesenchymal transition
EpCAM
epithelial cell adhesion molecule
IQR
interquartile range
KW test
Kruskal–Wallis test
MWU test
Mann–Whitney U test
NCR
nucleus/cytoplasm ratio
P2A
perimeter to area
PC
prostate cancer
TIF
tagged Image Format files
TXT
text file
μm
micrometer
µm2
square micrometers
  相似文献   
5.
《Clinical neurophysiology》2021,132(2):315-322
ObjectivePrevious studies have demonstrated voluntary movement alterations as well as motor cortex excitability and plasticity changes in patients with mild cognitive impairment (MCI). To investigate the pathophysiology of movement abnormalities in MCI, we tested possible relationships between movement abnormalities and primary motor cortex alterations in patients.MethodsFourteen amnestic MCI (aMCI) patients and 16 healthy controls were studied. Cognitive assessment was performed using clinical scales. Finger tapping was recorded by a motion analysis system. Transcranial magnetic stimulation was used to test the input/output curve of motor evoked potentials, intracortical inhibition, and short-latency afferent inhibition. Primary motor cortex plasticity was probed by theta burst stimulation. We investigated correlations between movement abnormalities, clinical scores, and cortical neurophysiological parameters.ResultsMCI patients showed less rhythmic movement but no other movement abnormalities. Cortical excitability measures were normal in patients, whereas plasticity was reduced. Movement rhythm abnormalities correlated with frontal dysfunction scores.ConclusionOur study in MCI patients demonstrated abnormal voluntary movement and plasticity changes, with no correlation between the two. Altered rhythm correlated with frontal dysfunction.SignificanceOur results contribute to the understanding of pathophysiological mechanisms of motor impairment in MCI.  相似文献   
6.
7.
Elevated serum uric acid (SUA) levels have been associated with several cardiovascular risk factors and the progression of coronary artery disease. In the setting of acute myocardial infarction, increasing evidence suggests that high SUA levels could be related to adverse outcomes. Interestingly elevated SUA levels have been linked to endothelial dysfunction, inflammation and oxidative stress. The aim of this review is to discuss the potential negative effects of SUA in patients with ST-segment elevation myocardial infarction undergoing primary percutaneous coronary intervention, analyzing the possible underlying pathophysiological mechanisms.  相似文献   
8.
ObjectiveThis study aimed to compare how children with overweight or obesity and their parents perceive the obesity-related terms used by healthcare professionals and investigate the factors associated with these perceptions.MethodsChildren and adolescents aged 8–16 years with overweight or obesity (n = 192) and their parents participated in the cross-sectional study by responding to a 5-point Likert-scale questionnaire on 10 obesity-related terms, including “chubby,” “weight problem,” “weight,” “overweight,” “BMI,” “obese,” “heavy,” “fleshy,” “fat,” and “severely obese.”ResultsFor both children and parents, “chubby” was the most desirable term (mean ± standard deviation: 3.50 ± 1.12 and 2.95 ± 0.83, respectively), and “severely obese” was the least acceptable term (2.83 ± 1.17 and 2.02 ± 1.02, respectively). Although the parents preferred all the terms less than the children did (p < 0.001), “weight problem” was considered most motivating for a child to lose weight (3.93 ± 0.94). Among children, older age and a larger self-perceived body size were associated with a more positive response towards obesity-related terms, whereas having internalized or externalized problems were negatively associated with these terms. Parents with a history of cardiovascular disease considered “severely obese” (β = ?0.419, [95% CI: ?0.739, ?0.099]) and “fat” (β = ?0.457, [95% CI: ?0.750, ?0.164]) less desirable.ConclusionsChildren and adolescents had a higher preference for obesity-related terms than their parents and preferred that healthcare professionals use euphemistic terms such as “chubby,” or neutral terms such as “weight problem.” Children with larger self-perceived body sizes or older age had a higher preference for obesity-related words. The terms used by healthcare professionals to describe excess weight must be motivating and respectful for all family members participating in the treatment.  相似文献   
9.
目的:探讨基于肿瘤浸润深度及大小的TTS评分系统对可切除胃癌患者预后判断的价值。方法:选择行根治性切除的234例胃癌患者为研究对象。根据肿瘤浸润深度(T分期)和肿瘤大小构建TTS评分系统,分为TTS 0级、1级、2级,代表肿瘤侵袭性逐渐升高。通过Cox多因素模型分析TTS评分系统作为预后判断工具的可行性。结果:T1-T4期患者肿瘤的平均大小分别为(3.3±2.7)cm、(4.1±3.1)cm、(6.6±3.1)cm、(9.4±4.9)cm。单因素分析显示,肿瘤浸润深度与肿瘤大小、淋巴结转移、TNM分期、淋巴浸润和血管浸润显著相关(P<0.01)。ROC曲线显示,45 mm为肿瘤大小的最佳界值,可有效区分患者是否存在淋巴结转移,曲线下面积(area under curve,AUC)为0.762。综合肿瘤大小的临界值和肿瘤浸润深度,构建TTS评分系统,TTS 0级、TTS 1级和TTS 2级的患者5年生存率分别为95.6%、83.3%和70.2%,两两比较后发现,不同TTS状态患者的生存率之间均存在显著差异(P<0.01)。Cox多因素分析发现,TTS评分是影响患者预后的独立性危险因素(P<0.05)。结论:本研究根据肿瘤浸润深度和大小构建了TTS评分系统,并证明了TTS评分与胃癌患者的预后密切相关。  相似文献   
10.
BackgroundIt is shown that tumour volume distributions can yield information on two aspects of cancer research: tumour induction and tumour control.Materials and methodsFrom the hypothesis that the intrinsic distribution of breast cancer volumes follows an exponential distribution, firstly the probability density function of tumour growth time was deduced via a mathematical transformation of the probability density functions of tumour volumes. In a second step, the distribution of tumour volumes was used to model the variation of the clonogenic cell number between patients in order to determine tumour control probabilities for radiotherapy patients.ResultsDistribution of lag times, i.e. the time from the appearance of the first fully malignant cell until a clinically observable cancer, can be used to deduce the probability of tumour induction as a function of patient age. The integration of the volume variation with a Poisson-TCP model results in a logistic function which explains population-averaged survival data of radiotherapy patients.ConclusionsThe inclusion of tumour volume distributions into the TCP formalism enables a direct link to be deduced between a cohort TCP model (logistic) and a TCP model for individual patients (Poisson). The TCP model can be applied to non-uniform tumour dose distributions.  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