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   440580篇
  免费   31194篇
  国内免费   7425篇
耳鼻咽喉   5559篇
儿科学   8876篇
妇产科学   10913篇
基础医学   60904篇
口腔科学   12858篇
临床医学   38517篇
内科学   87162篇
皮肤病学   9216篇
神经病学   30429篇
特种医学   16200篇
外国民族医学   123篇
外科学   66854篇
综合类   21397篇
现状与发展   18篇
一般理论   66篇
预防医学   21252篇
眼科学   11160篇
药学   37827篇
  72篇
中国医学   5758篇
肿瘤学   34038篇
  2021年   5430篇
  2020年   4179篇
  2019年   5021篇
  2018年   6804篇
  2017年   5399篇
  2016年   5477篇
  2015年   7046篇
  2014年   9505篇
  2013年   10511篇
  2012年   14627篇
  2011年   15672篇
  2010年   9353篇
  2009年   8224篇
  2008年   12747篇
  2007年   13643篇
  2006年   13691篇
  2005年   12629篇
  2004年   10936篇
  2003年   10636篇
  2002年   9933篇
  2001年   29646篇
  2000年   30280篇
  1999年   25358篇
  1998年   6167篇
  1997年   5344篇
  1996年   4641篇
  1995年   4340篇
  1994年   3853篇
  1993年   3314篇
  1992年   16555篇
  1991年   15254篇
  1990年   14542篇
  1989年   14277篇
  1988年   12848篇
  1987年   12251篇
  1986年   11278篇
  1985年   10443篇
  1984年   6986篇
  1983年   5642篇
  1982年   2731篇
  1979年   5505篇
  1978年   3345篇
  1977年   2963篇
  1975年   2636篇
  1974年   3064篇
  1973年   2863篇
  1972年   2828篇
  1971年   2773篇
  1970年   2509篇
  1969年   2543篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
91.
Hepatic myelopathy is a complication seen in patients with chronic liver failure with physiologic or iatrogenic portosystemic shunting. The main symptom is progressive lower limb dyskinesia. The role of the brain motor control center in hepatic myelopathy is unknown. This study aimed to investigate the gray matter changes in patients with hepatic myelopathy secondary to transjugular intrahepatic portosystemic shunt and to examine their clinical relevance. This was a cross-sectional study. Twenty-three liver failure patients with hepatic myelopathy(hepatic myelopathy group), 23 liver failure patients without hepatic myelopathy(non-hepatic myelopathy group) after transjugular intrahepatic portosystemic shunt, and 23 demographically matched healthy volunteers were enrolled from March 2014 to November 2016 at Xijing Hospital, Air Force Military Medical University(Fourth Military Medical University), China. High-resolution magnetization-prepared rapid gradient-echo brain imaging was acquired. Group differences in regional gray matter were assessed using voxel-based morphometry analysis. The relationship between aberrant gray matter and motor characteristics was investigated. Results demonstrated that compared with the non-hepatic myelopathy group, gray matter volume abnormalities were asymmetric, with decreased volume in the left insula(P = 0.003), left thalamus(P = 0.029), left superior frontal gyrus(P = 0.006), and right middle cingulate cortex(P = 0.021), and increased volume in the right caudate nucleus(P = 0.017), corrected with open-source software. The volume of the right caudate nucleus in the hepatic myelopathy group negatively correlated with the lower limb clinical rating of the Fugl-Meyer Assessment(r = –0.53, P = 0.01). Compared with healthy controls, patients with and without hepatic myelopathy exhibited overall increased gray matter volume in both thalami, and decreased gray matter volume in both putamen, as well as in the globus pallidus, cerebellum, and vermis. The gray matter abnormalities we found predominantly involved motor-related regions, and may be associated with motor dysfunction. An enlarged right caudate nucleus might help to predict weak lower limb motor performance in patients with preclinical hepatic myelopathy after transjugular intrahepatic portosystemic shunt. This study was approved by the Ethics Committee of Xijing Hospital, Air Force Military Medical University(Fourth Military Medical University), China(approval No. 20140227-6) on February 27, 2014.  相似文献   
92.
Objectives:To review the experience of 2 tertiary centers in Saudi Arabia with intracranial hypertension (IH) in the pediatric population.Methods:We retrospectively reviewed and analyzed pediatric patients diagnosed with IH from June 2002 to May 2017 in 2 institutes.Results:We identified 53 patients (30 females and 23 males) with a mean age of 7 years at the time of presentation. Among them, 41 patients were younger than 12 years, and 12 were older. Obese and overweight patients constituted 27.00% (n = 14) of all cases, 8 (66.7%) of whom were older than 12 years. The most common presenting feature was papilledema followed by headache. Vitamin D deficiency, which constituted the most common associated condition, was identified in 12 (22.6%) patients. Acetazolamide was the treatment option in 98.11% of patients, and only 5.7% underwent surgical interventions. The length of follow-up ranged from 6 months to 8 years.Conclusion:Intracranial hypertension is rare in children and commonly seen in overweight females older than 12 years similar to adults. Patients younger than 12 years tend to develop secondary IH. More studies are needed to characterize the clinical presentation and guide the management plan.

Intracranial hypertension (IH) is rarely reported in children. It is characterized by increased intracranial pressure (ICP) without any evidence of underlying brain pathology, structural abnormalities, hydrocephalus, or any abnormal meningeal enhancement.1 The incidence of IH differs from region to region due to variations in the prevalence of obesity and other secondary causes. The annual incidence of IH in children is 0.9 per 100,000 in the United States,2 0.5 per 100,000 in Germany,3 0.6 per 100,000 in Nova Scotia and Prince Edward Island in Eastern Canada,4 and 1.2 per 100,000 in Croatia.5 A study carried out in Oman estimated the incidence of IH to be 1.9 per 100,000 in children below 15 years of age; with it being higher in female children.6 The present study aimed to review the clinical presentation, possible aetiological factors, diagnosis, management, and outcomes in children with IH in 2 tertiary institutes in Saudi Arabia.  相似文献   
93.
94.
ObjectiveTo compare the baseline clinical characteristics between patients with ROS1-positive and ALK-positive advanced non-small cell lung cancer (NSCLC), and the correlations of these subtypes with the distribution of metastases.MethodsWe compared the clinical characteristics and imaging features of patients with ROS1-positive and ALK-positive NSCLC using statistical methods.ResultsData for 232 patients were analyzed. Compared with ALK-positive NSCLC, ROS1-positive NSCLC was more likely to occur in women (71% vs 53%), and primary lesions ≤3 cm were more common in patients with ROS1-positive compared with ALK-positive NSCLC (58% vs 37%). There was no significant difference in the distribution of metastases between the two groups. Subgroup analysis within the ROS1-positive group showed that, compared with primary lesions >3 cm, primary lesions ≤3 cm were more likely to present as peripheral tumors (72% vs 43%) and more likely to exhibit non-solid density (44% vs 4%).ConclusionsAlthough ROS1-positive and ALK-positive NSCLCs show similar clinical features, the differences may help clinicians to identify patients requiring further genotyping at initial diagnosis.  相似文献   
95.
96.
Sirt5 is known to functionally regulate mitochondrial proteins by altering posttranslational modifications, including lysine desuccinylation. While roles for Sirt5 as either a tumor promoter or suppressor, or in chemoresistance, have been implicated in other cancers, the function of Sirt5 in cutaneous melanoma has not been well examined. Therefore, to determine whether Sirt5 is necessary for BrafV600E‐mediated melanoma formation and/or disease progression, we crossed a genetically engineered murine melanoma model (TyrCreERT2/+; BrafLSLV600E/+; Ptenflox/flox) to Sirt5?/? knockout animals. In addition, we tested for synergism with a selective BRAF (V600E) inhibitor in Sirt5?/? mouse melanoma cells. Taken together, this report demonstrates that, in these models, Sirt5 is dispensable for BrafV600E‐mediated cutaneous melanoma formation and growth in vivo, and does not improve sensitivity to a selective BRAF inhibitor.  相似文献   
97.
The European Academy of Dermatology and Venereology (EADV) Task Forces (TFs) on Quality of Life (QoL) and Patient Oriented Outcomes, Melanoma and Non‐Melanoma Skin Cancer (NMSC) present a review of the literature and position statement on health‐related (HR) QoL assessment in skin cancer patients. A literature search was carried out to identify publications since 1980 that included information about the impact of SC on QoL. Generic, dermatology‐specific, cancer‐specific, SC‐specific, facial SC‐specific, NMSC‐specific, basal cell carcinoma‐specific and melanoma‐specific QoL questionnaires have been used to assess HRQoL in SC patients. HRQoL was assessed in the context of creation and validation of the HRQoL instruments, clinical trials, comparison of QoL in SC and other cancers, other diseases or controls, HRQoL assessment after treatment, comorbidities, behaviour modification, predictors of QoL and survival, supportive care needs, coping strategies and fear of cancer recurrence. The most widely used instruments for HRQoL assessment in SC patients are the European Organisation for Research and Treatment of Cancer Core Questionnaire (EORTC QLQ‐C30), the Functional Assessment of Cancer Therapy‐Melanoma (FACT‐M), Skin Cancer Index (SCI), Short Form 36 Item Health Survey (SF‐36) and the Dermatology Life Quality Index (DLQI). The TFs recommend the use of the cancer‐specific EORTC QLQ‐C30, especially in late stages of disease, and the melanoma‐specific FACT‐M and SC‐specific SCI questionnaires. These instruments have been well validated and used in several studies. Other HRQoL instruments, also with good basic validation, are not currently recommended because the experience of their use is too limited. Dermatology‐specific HRQoL instruments can be used to assess the impact of skin‐related problems in SC. The TFs encourage further studies to validate HRQoL instruments for use in different stages of SC, in order to allow more detailed practical recommendations on HRQoL assessment in SC.  相似文献   
98.
99.

Background

Accounts of cognitive processes in judgment and decision-making are frequently based on a dual-process framework, which reflects two qualitatively different types of processing: intuitive (Type 1) and analytical (Type 2) processes.

Objective

The present study investigated the effects of bilateral transcranial direct current stimulation (tDCS) to the dorsolateral prefrontal cortex (DLPFC) on judgment and decision-making performance.

Methods

Participants received anodal tDCS stimulation to the right DLPFC, left DLPFC or sham. There were 3 tasks: vignettes measuring heuristic thinking, belief bias syllogisms, and the cognitive reflection test (CRT), a measure of the ability to inhibit automatic responses to reach a correct solution. Fifty-four participants (mean age?=?24.63?±?4.46 years; 29 females) were recruited.

Results

Results showed that anodal tDCS to the right DLPFC was associated with an increase in cognitive reflection performance (Type 2 processing) as compared to left DLPFC and to sham. Logic thinking was reduced following anodal tDCS to the left DLPFC.

Conclusion

These findings are broadly consistent with a dual process framework, and cannot be explained by differences in cognitive ability and thinking style. The results demonstrate the involvement of the right DLPFC in cognitive reflection, and suggest the possibility of improving cognitive performance through tDCS.  相似文献   
100.
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