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   23946篇
  免费   1176篇
  国内免费   122篇
耳鼻咽喉   326篇
儿科学   365篇
妇产科学   498篇
基础医学   3020篇
口腔科学   672篇
临床医学   1767篇
内科学   6481篇
皮肤病学   262篇
神经病学   1823篇
特种医学   746篇
外科学   4134篇
综合类   103篇
一般理论   1篇
预防医学   737篇
眼科学   351篇
药学   1611篇
中国医学   45篇
肿瘤学   2302篇
  2022年   172篇
  2021年   402篇
  2020年   229篇
  2019年   260篇
  2018年   390篇
  2017年   301篇
  2016年   360篇
  2015年   375篇
  2014年   529篇
  2013年   656篇
  2012年   1015篇
  2011年   1120篇
  2010年   610篇
  2009年   545篇
  2008年   1060篇
  2007年   1146篇
  2006年   1074篇
  2005年   1014篇
  2004年   1032篇
  2003年   1006篇
  2002年   1059篇
  2001年   901篇
  2000年   932篇
  1999年   802篇
  1998年   295篇
  1997年   221篇
  1996年   208篇
  1995年   185篇
  1994年   164篇
  1993年   144篇
  1992年   602篇
  1991年   629篇
  1990年   534篇
  1989年   545篇
  1988年   525篇
  1987年   503篇
  1986年   430篇
  1985年   433篇
  1984年   318篇
  1983年   241篇
  1979年   233篇
  1978年   137篇
  1977年   138篇
  1974年   129篇
  1973年   123篇
  1972年   137篇
  1971年   127篇
  1970年   115篇
  1969年   137篇
  1967年   131篇
排序方式: 共有10000条查询结果,搜索用时 234 毫秒
991.
Although patients with major depressive disorder typically have a reduced hippocampal volume, particularly in the cornu ammonis 1 (CA1), animal studies suggest that depressive mood is related to the dentate gyrus (DG). In this study, our objective was to clarify which hippocampal subregions are functionally associated with depressive mood in humans. We conducted a functional MRI (fMRI) study on 27 cognitively intact volunteers. Subjects performed a modified version of a delayed matching‐to‐sample task in an MRI scanner to investigate pattern separation‐related activity during each phase of encoding, delay, and retrieval. In each trial, subjects learned a pair of sample cues. Functional MR images were acquired at a high spatial resolution, focusing on the hippocampus. Subjects also completed the Beck Depression Inventory (BDI), a questionnaire about depressive mood. Depending on the similarity between sample cues, activity in the DG/CA3 and medial CA1 in the anterior hippocampus changed only during encoding. Furthermore, the DG/CA3 region was more active during successful encoding trials compared to false trials. Activity in the DG/CA3 and lateral CA1 was negatively correlated with BDI scores. These results suggest that the DG/CA3 is the core region for pattern separation during the encoding phase and interacts with the medial CA1, depending on the similarity of the stimuli, to achieve effective encoding. Impaired activity in the DG/CA3, as well as in the lateral CA1, was found to be associated with depressive symptoms, even at a subclinical level. © 2013 Wiley Periodicals, Inc.  相似文献   
992.
993.
HIV-associated salivary gland disease refers to the pathology in head and neck lesions such as ranula, salivary gland swelling, xerostomia, and benign lymphoepithelial cysts in the parotid gland. Here, we present a unique case of the ranula patient with HIV infection treated with OK-423 sclerotherapy. Case report: The patient was a 42-year-old Japanese male with a few months history of oral floor swelling. Computed tomography (CT) showed a low-density area limited within the right floor of the mouth. Magnetic resonance imaging (MRI) revealed a distinct T2-high intensity area localized on the same location. The puncture fluid was bloody mucus, and the cytology was no malignancy. We diagnosed a simple ranula. He was, however, found to be HIV-antibody positive at the examination before treatment by chance. He was referred to the department of infectious diseases and definitively diagnosed HIV infection by western blot. We chose OK-432 sclerotherapy because of its minimally invasive and the risk of HIV infecting medical staff. Two times OK-432 injection made the lesion disappear. Conclusion: The case indicated that OK-432 sclerotherapy could be effective for ranula related to HIV.  相似文献   
994.
995.
996.

Background

For almost 30 years, transanal endoscopic microsurgery (TEM) has been the mainstay treatment for large rectal lesions. With the advent of endoscopic submucosal dissection (ESD), flexible endoscopy has aimed at en bloc R0 resection of superficial lesions of the digestive tract. This systematic review and meta-analysis compared the safety and effectiveness of ESD and full-thickness rectal wall excision by TEM in the treatment of large nonpedunculated rectal lesions preoperatively assessed as noninvasive.

Methods

A systematic review of the literature published between 1984 and 2010 was conducted (Registration no. CRD42012001882). Data were integrated with those from the original databases requested from the study authors when needed. Pooled estimates of the proportions of patients with en bloc R0 resection, complications, recurrence, and need for further treatment in the ESD and TEM series were compared using random-effects single-arm meta-analysis.

Results

This review included 11 ESD and 10 TEM series (2,077 patients). The en bloc resection rate was 87.8 % (95 % confidence interval [CI] 84.3–90.6) for the ESD patients versus 98.7 % (95 % CI 97.4–99.3 %) for the TEM patients (P < 0.001). The R0 resection rate was 74.6 % (95 % CI 70.4–78.4 %) for the ESD patients versus 88.5 % (95 % CI 85.9–90.6 %) for the TEM patients (P < 0.001). The postoperative complications rate was 8.0 % (95 %, CI 5.4–11.8 %) for the ESD patients versus 8.4 % (95 % CI 5.2–13.4 %) for the TEM patients (P = 0.874). The recurrence rate was 2.6 % (95 % CI 1.3–5.2 %) for the ESD patients versus 5.2 % (95 % CI 4.0–6.9 %) for the TEM patients (P < 0.001). Nevertheless, the rate for the overall need of further abdominal treatment, defined as any type of surgery performed through an abdominal access, including both complications and pathology indications, was 8.4 % (95 % CI 4.9–13.9 %) for the ESD patients versus 1.8 % (95 % CI 0.8–3.7 %) for the TEM patients (P < 0.001).

Conclusions

The ESD procedure appears to be a safe technique, but TEM achieves a higher R0 resection rate when performed in full-thickness fashion, significantly reducing the need for further abdominal treatment.  相似文献   
997.
DJ-1 is a protein that is associated with Parkinson disease and cancer, and the reduction of DJ-1 function and expression is also thought to be a cause of diabetes and hypertension. However, little is known about the association between the plasma concentration of DJ-1 and risk of metabolic syndrome. We hypothesized that a lifestyle intervention would increase serum DJ-1 and that up-regulated DJ-1 functions will result in the prevention of metabolic syndrome. The objective of our study is to examine whether the level of serum DJ-1 is associated with the risk of metabolic syndrome. Therefore, to reveal the association between DJ-1 and metabolic syndrome, this study investigated lifestyle intervention in a control group (n = 37) and intervention group (n = 45). The results showed that body mass index, body fat ratio, waist-hip ratio, waist circumference, blood pressure, and plasma glucose level were improved in the intervention group, as compared with those in the control group. Furthermore, serum levels of DJ-1 were increased in the intervention group, when compared with those in the control group. These results suggest that serum DJ-1 is increased by lifestyle intervention and that increased serum DJ-1 prevents metabolic syndrome. Thus, the level of serum DJ-1 will become one of the indexes for the risk of metabolic syndrome.  相似文献   
998.
The purpose of this study was to retrospectively evaluate the incidence of delayed renal dysfunction after total body irradiation (TBI) in long-term survivors of TBI/hematopoietic stem cell transplantation (HSCT). Between 1989 and 2006, 24 pediatric patients underwent TBI as part of the conditioning regimen for HSCT at Chiba University Hospital. Nine patients who survived for more than 5 years were enrolled in this study. No patient had any evidence of renal dysfunction prior to the transplant according to their baseline creatinine levels. The median age at the time of diagnosis was 6 years old (range: 1–17 years old). The follow-up period ranged from 79–170 months (median: 140 months). Renal dysfunction was assessed using the estimated glomerular filtration rate (eGFR). The TBI dose ranged from 8–12 Gy delivered in 3–6 fractions over 2–3 d. The patients were treated with linear accelerators in the supine position, and the radiation was delivered to isocentric right–left and left–right fields via the extended distance technique. The kidneys and the liver were not shielded except in one patient with a left adrenal neuroblastoma. No patient required hemodialysis. The eGFR of four patients (44.4%) progressively decreased. The remaining patients did not demonstrate any eGFR deterioration. Only one patient developed hypertension. By evaluating the changes in eGFR, renal dysfunction among long-term survivors of TBI/HSCT could be detected. Our results suggested that the TBI schedule of 12 Gy in 6 fractions over three consecutive days affects renal function.  相似文献   
999.

Purpose

To understand the influence of disease and treatment on the health-related quality of life (HRQOL) of children with brain tumors, compared to the HRQOL of children with other cancers, from the viewpoints of children and parents.

Methods

A total of 133 children aged 5–18 years and 165 parents of children aged 2–18 completed questionnaires of the Pediatric Quality of Life Inventory Cancer Module (Pain and Hurt, Nausea, Procedural Anxiety, Treatment Anxiety, Worry, Cognitive Problems, Perceived Physical Appearance, and Communication scales); higher scores indicate a better HRQOL. The Cancer Module scores, weighted by age and treatment status, were compared to those obtained in a previous study of children with other cancers (mostly leukemia).

Results

The weighted mean scores for Pain and Hurt (effect size d = 0.26) and Nausea (d = 0.23) from child reports and the scores for Nausea (d = 0.28) from parent reports were higher for children with brain tumors than scores for children with other cancers. The scores for Procedural Anxiety (d = ?0.22) and Treatment Anxiety (d = ?0.32) from parent reports were lower for parents of children with brain tumors than the scores for parents of children with other cancers. The child-reported Pain and Hurt score of the Cancer Module was higher (d = 0.29) and in less agreement (intraclass correlation coefficient = 0.43) with scores from the Brain Tumor Module, indicating that assessments completed with the Cancer Module misesteem pain and hurt problems in children with brain tumors.

Conclusions

The profiles of cancer-specific HRQOL in children with brain tumors differ from those of children with other cancers; we therefore suggest that these children receive specific psychological support.  相似文献   
1000.
Signal regulatory protein α (SIRPα) is expressed predominantly on type 2 conventional dendritic cells (cDC2s) and macrophages. We previously showed that mice systemically lacking SIRPα were resistant to experimental autoimmune encephalomyelitis (EAE). Here, we showed that deletion of SIRPα in CD11c+ cells of mice (SirpaΔDC mice) also markedly ameliorated the development of EAE. The frequency of cDCs and migratory DCs (mDCs), as well as that of Th17 cells, were significantly reduced in draining lymph nodes of SirpaΔDC mice at the onset of EAE. In addition, we found the marked reduction in the number of Th17 cells and DCs in the CNS of SirpaΔDC mice at the peak of EAE. Whereas inducible systemic ablation of SIRPα before the induction of EAE prevented disease development, that after EAE onset did not ameliorate the clinical signs of disease. We also found that EAE development was partially attenuated in mice with CD11c+ cell-specific ablation of CD47, a ligand of SIRPα. Collectively, our results suggest that SIRPα expressed on CD11c+ cells, such as cDC2s and mDCs, is indispensable for the development of EAE, being required for the priming of self-reactive Th17 cells in the periphery as well as for the inflammation in the CNS.  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