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   718篇
  免费   41篇
  国内免费   5篇
耳鼻咽喉   9篇
儿科学   14篇
妇产科学   12篇
基础医学   77篇
口腔科学   26篇
临床医学   59篇
内科学   168篇
皮肤病学   24篇
神经病学   40篇
特种医学   38篇
外科学   114篇
综合类   2篇
预防医学   20篇
眼科学   25篇
药学   55篇
中国医学   2篇
肿瘤学   79篇
  2024年   1篇
  2023年   5篇
  2022年   16篇
  2021年   33篇
  2020年   29篇
  2019年   17篇
  2018年   30篇
  2017年   21篇
  2016年   24篇
  2015年   21篇
  2014年   35篇
  2013年   35篇
  2012年   39篇
  2011年   49篇
  2010年   27篇
  2009年   21篇
  2008年   39篇
  2007年   43篇
  2006年   40篇
  2005年   55篇
  2004年   38篇
  2003年   45篇
  2002年   31篇
  2001年   6篇
  2000年   4篇
  1999年   4篇
  1998年   12篇
  1997年   6篇
  1996年   6篇
  1995年   5篇
  1994年   2篇
  1993年   4篇
  1992年   2篇
  1991年   1篇
  1990年   3篇
  1989年   5篇
  1988年   1篇
  1987年   1篇
  1986年   1篇
  1985年   1篇
  1984年   1篇
  1983年   1篇
  1982年   1篇
  1981年   1篇
  1973年   1篇
  1971年   1篇
排序方式: 共有764条查询结果,搜索用时 406 毫秒
31.
We retrospectively investigated clinical outcomes and prognostic factors of 131 patients with transplant-ineligible newly diagnosed multiple myeloma (NDMM) who received melphalan and prednisolone (MP) as first-line therapy from 2006 to 2013. Eighty-one patients received salvage therapies incorporating bortezomib, lenalidomide, and/or thalidomide. The overall response rate to MP was 54.2 %, including 9.2 % of better than very good partial response. With a median follow-up period of 30.2 months, median overall survival (OS) and median time to next treatment (TNT) were 54.4 and 19.0 months, respectively. Univariate analysis revealed that performance status and serum calcium level significantly associated with both OS and TNT, and multivariate analysis revealed that the higher serum calcium level had a significantly unfavorable impact on OS and TNT. Importantly, staging informed by the international staging system (ISS) was not predictive for OS or TNT in the analyzed cohort. Our study revealed that, in the context of first-line MP therapy for NDMM, the salvage therapy incorporating novel agents produced a survival period of >30 months after the initiation of second-line therapy, suggesting that the predictive value of ISS for OS and TNT may be limited in the era of novel agents.  相似文献   
32.
33.
The reproducibility of neurite orientation dispersion and density imaging (NODDI) metrics in the human brain has not been explored across different magnetic resonance (MR) scanners from different vendors. This study aimed to evaluate the scan–rescan and inter-vendor reproducibility of NODDI metrics in white and gray matter of healthy subjects using two 3-T MR scanners from two vendors. Ten healthy subjects (7 males; mean age 30 ± 7 years, range 23–37 years) were included in the study. Whole-brain diffusion-weighted imaging was performed with b-values of 1000 and 2000 s/mm2 using two 3-T MR scanners from two different vendors. Automatic extraction of the region of interest was performed to obtain NODDI metrics for whole and localized areas of white and gray matter. The coefficient of variation (CoV) and intraclass correlation coefficient (ICC) were calculated to assess the scan–rescan and inter-vendor reproducibilities of NODDI metrics. The scan–rescan and inter-vendor reproducibility of NODDI metrics (intracellular volume fraction and orientation dispersion index) were comparable with those of diffusion tensor imaging (DTI) metrics. However, the inter-vendor reproducibilities of NODDI (CoV = 2.3–14%) were lower than the scan–rescan reproducibility (CoV: scanner A = 0.8–3.8%; scanner B = 0.8–2.6%). Compared with the finding of DTI metrics, the reproducibility of NODDI metrics was lower in white matter and higher in gray matter. The lower inter-vendor reproducibility of NODDI in some brain regions indicates that data acquired from different MRI scanners should be carefully interpreted.  相似文献   
34.
The aim of this study was to examine the applicability of the linear-quadratic (LQ) model to single and fractionated irradiation in EMT6 cells. First, the α/β ratio of the cells was determined from single-dose experiments, and a biologically effective dose (BED) for 20 Gy in 10 fractions (fr) was calculated. Fractional doses yielding the same BED were calculated for 1-, 2-, 3-, 4-, 5-, 7-, 15- and 20-fraction irradiation using LQ formalism, and then irradiation with these schedules was actually given. Cell survival was determined by a standard colony assay. Differences in cell survival between pairs of groups were compared by t-test. The α/β ratio of the cells was 3.18 Gy, and 20 Gy in 10 fr corresponded to a BED3.18 of 32.6 Gy. The effects of 7-, 15- and 20-fraction irradiation with a BED3.18 of 32.6 Gy were similar to those of the 10-fraction irradiation, while the effects of 1- to 5-fraction irradiation were lower. In this cell line, the LQ model was considered applicable to 7- to 20-fraction irradiation or doses per fraction of 2.57 Gy or smaller. The LQ model might be applicable in the dose range below the α/β ratio.  相似文献   
35.
36.
37.
Cytotoxic T-lymphocyte-associated antigen 4 (CTLA4) is a coinhibitory receptor that plays an essential role in maintaining immune system homeostasis by suppressing T-cell activation. We report a sporadic case of CTLA4 haploinsufficiency in a patient with Epstein–Barr virus-positive diffuse large B-cell lymphoma and subsequent benign lymphadenopathy. A missense mutation in exon 2 of the CTLA4 gene (c.251T>C, p.V84A) was found in the patient’s peripheral blood and buccal cell DNA, but not in her parents’ DNA. CTLA4 expression decreased in the peripheral regulatory T cells upon stimulation, whereas CTLA4 and PD-1-positive T cell subsets increased, possibly to compensate for the defective CTLA4 function. This case suggests that some adult lymphoma patients with no remarkable medical history have primary immune disorder. As immune-targeted therapies are now widely used for the treatment of malignancies, it is increasingly important to recognize the underlying primary immune disorders to properly manage the disease and avoid unexpected complications of immunotherapies.  相似文献   
38.
Rationale:McCune–Albright syndrome (MAS) is a rare disorder characterized by clinical findings, which includes fibrous dysplasia (FD). FD is a benign tumor that leads to increased rates of bone fracture. In some MAS cases with FD, facial deformities, severe pain, and orbital neuropathies are complicated. Aneurysmal bone cyst (ABC) is a benign bone tumor and rare complication of FD.Patient concerns:A 9-year-old boy was admitted to our hospital because of acute visual disturbance.Diagnosis and interventions:The patient was clinically diagnosed as ABC complicated with MAS, and he underwent surgery.Outcomes:After the surgery, his sight became normal. Recurrence of ABC and visual disturbance was not observed in 3 years. Genetic analysis of a tissue sample from the ABC lesion by next-generation sequencing revealed a somatic activating GNAS mutation.Lessons:To the best of our knowledge, this is the first case report of MAS causing optic neuropathy complicated with ABC. ABC complicated with MAS is extremely rare, but it should be considered as a possible diagnosis in patients with acute visual loss and facial swelling. In addition, our case had OAS, which is an uncommon syndrome and a rare complication in ABC with MAS, and rapid decompression of the ABC was effective in improving the patient''s eyesight.  相似文献   
39.
Neuropeptide Y (NPY) is one of a number of neuropeptides with powerful orexigenic effects. Intracerebroventricular administration of NPY induces increases in food intake and alters feeding rate. Besides it role in feeding behavior, NPY also has significant effects on neuronal systems related to other spontaneous behaviors such as rearing and grooming. In the present study, we examined the direct effects of NPY on mesencephalic V neurons (Mes V), which are important sensory neurons involved in oral motor reflexes and rhythmical jaw movements, as well as masticatory proprioception. Coronal brain slices were prepared from neonatal Sprague-Dawley rats (P3-17) and whole-cell patch clamp recordings were obtained from Mes V neurons. Bath application of NPY depolarized the membrane potential and induced inward current in most neurons. Application of NPY shortened the duration of the afterhyperpolarization following an action potential, and increased the mean spike frequency during repetitive discharge. In those neurons which exhibited rhythmical burst discharge in response to maintained current injection, the bursting frequency was also increased. These effects were mediated predominately by both Y1 and Y5 receptors.  相似文献   
40.
Neurocognitive and psychiatric disorders have significant consequences for quality of life in patients with Parkinson's disease (PD). In the current study, we evaluated microstructural white matter (WM) alterations associated with neurocognitive and psychiatric disorders in PD using neurite orientation dispersion and density imaging (NODDI) and linked independent component analysis (LICA). The indices of NODDI were compared between 20 and 19 patients with PD with and without neurocognitive and psychiatric disorders, respectively, and 25 healthy controls using tract-based spatial statistics and tract-of-interest analyses. LICA was applied to model inter-subject variability across measures. A widespread reduction in axonal density (indexed by intracellular volume fraction [ICVF]) was demonstrated in PD patients with and without neurocognitive and psychiatric disorders, as compared with healthy controls. Compared with patients without neurocognitive and psychiatric disorders, patients with neurocognitive and psychiatric disorders exhibited more extensive (posterior predominant) decreases in axonal density. Using LICA, ICVF demonstrated the highest contribution (59% weight) to the main effects of diagnosis that reflected widespread decreases in axonal density. These findings suggest that axonal loss is a major factor underlying WM pathology related to neurocognitive and psychiatric disorders in PD, whereas patients with neurocognitive and psychiatric disorders had broader axonal pathology, as compared with those without. LICA suggested that the ICVF can be used as a useful biomarker of microstructural changes in the WM related to neurocognitive and psychiatric disorders in PD.  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