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   2780篇
  免费   122篇
  国内免费   12篇
耳鼻咽喉   29篇
儿科学   65篇
妇产科学   25篇
基础医学   254篇
口腔科学   71篇
临床医学   201篇
内科学   827篇
皮肤病学   36篇
神经病学   130篇
特种医学   196篇
外科学   465篇
综合类   21篇
一般理论   2篇
预防医学   62篇
眼科学   45篇
药学   201篇
中国医学   4篇
肿瘤学   280篇
  2023年   22篇
  2022年   47篇
  2021年   88篇
  2020年   59篇
  2019年   59篇
  2018年   86篇
  2017年   59篇
  2016年   64篇
  2015年   49篇
  2014年   77篇
  2013年   109篇
  2012年   134篇
  2011年   151篇
  2010年   89篇
  2009年   66篇
  2008年   111篇
  2007年   130篇
  2006年   126篇
  2005年   137篇
  2004年   122篇
  2003年   124篇
  2002年   115篇
  2001年   81篇
  2000年   79篇
  1999年   56篇
  1998年   33篇
  1997年   16篇
  1996年   21篇
  1995年   20篇
  1994年   16篇
  1993年   12篇
  1992年   35篇
  1991年   26篇
  1990年   38篇
  1989年   47篇
  1988年   42篇
  1987年   29篇
  1986年   34篇
  1985年   29篇
  1984年   25篇
  1983年   22篇
  1979年   16篇
  1978年   13篇
  1977年   12篇
  1974年   20篇
  1973年   16篇
  1972年   22篇
  1971年   29篇
  1970年   21篇
  1969年   12篇
排序方式: 共有2914条查询结果,搜索用时 15 毫秒
101.
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   
102.
103.
104.
Incidence of Urolithiasis in Northeast Thailand   总被引:3,自引:0,他引:3  
Background :
Urolithiasis is a major health problem in the northeast part of Thailand. In this study, we examined the prevalence of renal stone disease and differences of urinary components between stone formers and healthy control subjects in northeastern rural areas of Thailand.
Methods :
We selected 3 villages in the rural areas of Khon Kaen province in northeast Thailand. Three hundred and sixty-seven persons were asked questions relating to urolithiasis and were examined by abdominal ultrasound (US). We collected a spot urine sample from stone formers and healthy control subjects from each village.
Results :
Abnormal findings by US were detected in 39 individuals (10.6%), and included 31 individuals with renal calculi (8.4%), 16 with hydronephrosis (4.4%), and 1 individual with a renal cyst (0.3%). This yielded a disease rate of urinary stones in this study of 16.9%. The male/female ratio was 2/1 and the average age of the individuals examined was 40.3 + 13.9 years. However, there was no significant difference between the urinary parameters of stone formers and the healthy control subjects. Conclusion: There was a high incidence of renal stone disease in the northeast part of Thailand, but the tendency for hypocitraturia was only found in stone formers.  相似文献   
105.
A 21-year-old Japanese man without known diabetes mellitus had abdominal pain. The diagnosis was ketoacidosis and hypertriglyceridemia-induced acute pancreatitis. He had polydipsia and polyuria and had habitually drunk several soft drinks every day for two years. After hospitalization, despite adequate liquid intake, dehydration remained with hypotonic polyuria. Further examinations revealed the coexistence of central diabetes insipidus (CDI), possibly caused by lymphocytic infundibulo-neurohypophysitis, based on anti-rabphilin-3A antibody positivity. Although CDI had been undiagnosed for two years, over-consumption of sugar-rich soft drinks to ease thirst caused ketoacidosis, hypertriglyceridemia, and acute pancreatitis. There are no previous reports of this three-part combination of symptoms caused by CDI.  相似文献   
106.
To evaluate the diagnostic value of dual-phase cone beam CT during hepatic arteriography (CBCTHA) for hepatocellular carcinoma (HCC).Thirty seven patients with unresectable HCC underwent the dual-phase CBCTHA prior to transarterial chemoembolization (TACE). Three blinded observers independently reviewed and compared the first phase CBCTHA images alone and the dual phase CBCTHA images. Diagnostic accuracy was evaluated by the alternative free-response receiver operating characteristic method (Area under the curve: Az value). Sensitivities were analyzed with the paired t test. The analysis was performed for overall HCCs, HCCs up to 1 cm and those larger than 1 cm.For all HCCs and HCCs up to 1 cm, Az value and sensitivity showed no significant difference between the first-phase CBCTHA alone and the dual-phase CBCTHA (Az: 0.81 vs 0.88, P = .07, 0.79 and 0.85, P = .14, sensitivity: 0.61 and 0.73, P = .11, 0.41 and 0.52, P = .33, respectively). For HCCs larger than 1 cm, the mean Az value and sensitivity for the dual-phase CBCTHA were significantly higher than those for the first phase CBCTHA alone (Az: 0.96 vs 0.92, P = .008, sensitivity: 0.85 vs 0.75, P = .013, respectively).The diagnostic accuracy of the dual-phase CBCTHA was superior to that of the first phase CBCTHA alone in the diagnosis of HCC larger than 1 cm.  相似文献   
107.
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   
108.
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   
109.
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   
110.
IntroductionChronic Eustachian tube dysfunction can cause several symptoms and middle ear conditions that can impact patient quality of life. It is estimated to be relatively frequent, affecting approximately 5% of adults. The diagnostic tools for this condition are still inadequate. In 2012, McCoul et al. published a questionnaire for the evaluation of Eustachian tube dysfunction named ETDQ-7. They established its replicability and validity. The cutoff point for the diagnosis of chronic Eustachian tube dysfunction was equal to or greater than 14.5, with 100% sensitivity and 100% specificity.ObjectiveTo translate, adapt and validate the ETDQ-7 questionnaire to Brazilian Portuguese.MethodsWe translated the questionnaire into Brazilian Portuguese and applied it to 50 patients, 20 of whom had chronic Eustachian tube dysfunction, and 30 controls.ResultsThe results obtained with the North-American questionnaire were confirmed in its Brazilian version. The cut-off point for the diagnosis of chronic Eustachian tube dysfunction was ≥14, also exhibiting high sensitivity and specificity, very similar to that of ETDQ-7.ConclusionIt is recommended that ETDQ-7 be used to complement the clinical history of patients with chronic Eustachian tube dysfunction; it can also be used as an important tool for diagnosis, patient follow-up and treatment management.  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