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   6094篇
  免费   385篇
  国内免费   126篇
耳鼻咽喉   103篇
儿科学   128篇
妇产科学   64篇
基础医学   947篇
口腔科学   152篇
临床医学   594篇
内科学   1283篇
皮肤病学   132篇
神经病学   474篇
特种医学   485篇
外科学   772篇
综合类   114篇
预防医学   273篇
眼科学   62篇
药学   507篇
中国医学   79篇
肿瘤学   436篇
  2024年   4篇
  2023年   60篇
  2022年   180篇
  2021年   263篇
  2020年   128篇
  2019年   129篇
  2018年   168篇
  2017年   162篇
  2016年   228篇
  2015年   362篇
  2014年   406篇
  2013年   447篇
  2012年   585篇
  2011年   554篇
  2010年   320篇
  2009年   301篇
  2008年   348篇
  2007年   344篇
  2006年   261篇
  2005年   176篇
  2004年   127篇
  2003年   105篇
  2002年   92篇
  2001年   101篇
  2000年   78篇
  1999年   57篇
  1998年   101篇
  1997年   70篇
  1996年   66篇
  1995年   57篇
  1994年   49篇
  1993年   49篇
  1992年   22篇
  1991年   7篇
  1990年   17篇
  1989年   22篇
  1988年   25篇
  1987年   16篇
  1986年   21篇
  1985年   17篇
  1984年   9篇
  1983年   12篇
  1982年   9篇
  1981年   4篇
  1980年   8篇
  1979年   4篇
  1978年   6篇
  1977年   6篇
  1976年   12篇
  1975年   9篇
排序方式: 共有6605条查询结果,搜索用时 15 毫秒
71.
72.
We report the sonographic appearance of a rare case of neuritis ossificans of the median nerve at the wrist, which appeared as a hyperechoic lesion around the nerve. Diagnosis was confirmed with magnetic resonance imaging (MRI).  相似文献   
73.
74.
A solitary adrenal gland spanning the midline has been alternatively described as “Horseshoe” or “Butterfly” and is a rare congenital abnormality almost exclusively associated with neonates. There have been 65 reported cases in fetuses and infants, based on ultrasound and autopsy findings. Horseshoe adrenal gland is associated with several congenital anomalies, such as asplenia (52 %), neural tube defects (37 %), renal abnormalities (29 %), and diaphragmatic defects (1 %). Recently, Feldman and colleagues [2] reported the first case of an adult male with horseshoe adrenal gland and posterior midline diaphragmatic anomaly found incidentally with CT imaging. We present a second case of asymptomatic adult horseshoe adrenal gland with posterior midline diaphragmatic hernia in a 51-year-old woman discovered on CT imaging. In our patient these abnormalities were also associated with a 9th thoracic butterfly vertebrae and a unilateral region of underdevelopment of the paraspinal musculature at the level of the diaphragmatic defect. To our knowledge, this is the first time this abnormality has been documented with MRI.  相似文献   
75.
AJ  Fay  T  McMahon  C  Im  C  Bair-Marshall  KJ  Niesner  H  Li  A  Nelson  SM  Voglmaier  Y-H  Fu  LJ  Ptáček 《Neurogenetics》2021,22(3):171-185

Paroxysmal kinesigenic dyskinesia is an episodic movement disorder caused by dominant mutations in the proline-rich transmembrane protein PRRT2, with onset in childhood and typically with improvement or resolution by middle age. Mutations in the same gene may also cause benign infantile seizures, which begin in the first year of life and typically remit by the age of 2 years. Many details of PRRT2 function at the synapse, and the effects of mutations on neuronal excitability in the pathophysiology of epilepsy and dyskinesia, have emerged through the work of several groups over the last decade. However, the age dependence of the phenotypes has not been explored in detail in transgenic models. Here, we report our findings in heterozygous and homozygous Prrt2 knockout mice that recapitulate the age dependence of dyskinesia seen in the human disease. We show that Prrt2 deletion reduces the levels of synaptic proteins in a dose-dependent manner that is most pronounced at postnatal day 5 (P5), attenuates at P60, and disappears by P180. In a test for foot slippage while crossing a balance beam, transient loss of coordination was most pronounced at P60 and less prominent at age extremes. Slower traverse time was noted in homozygous knockout mice only, consistent with the ataxia seen in rare individuals with biallelic loss of function mutations in Prrt2. We thus identify three age-dependent phenotypic windows in the mouse model, which recapitulate the pattern seen in humans with PRRT2-related diseases.

  相似文献   
76.
PurposeTo compare image quality in selective intracoronary contrast-injected computed tomography angiography (Selective-CTA) with that in conventional intravenous contrast-injected CTA (IV-CTA).Materials and MethodsSix pigs (35 to 40 kg) underwent both IV-CTA using an intravenous injection (60 mL) and Selective-CTA using an intracoronary injection (20 mL) through a guide-wire during/after percutaneous coronary intervention. Images of the common coronary artery were acquired. Scans were performed using a combined machine comprising an invasive coronary angiography suite and a 320-channel multi-slice CT scanner. Quantitative image quality parameters of CT attenuation, image noise, signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), mean lumen diameter (MLD), and mean lumen area (MLA) were measured and compared. Qualitative analysis was performed using intraclass correlation coefficient (ICC), which was calculated for analysis of interobserver agreement.ResultsQuantitative image quality, determined by assessing the uniformity of CT attenuation (399.06 vs. 330.21, p<0.001), image noise (24.93 vs. 18.43, p<0.001), SNR (16.43 vs. 18.52, p=0.005), and CNR (11.56 vs. 13.46, p=0.002), differed significantly between IV-CTA and Selective-CTA. MLD and MLA showed no significant difference overall (2.38 vs. 2.44, p=0.068, 4.72 vs. 4.95, p=0.078). The density of contrast agent was significantly lower for selective-CTA (13.13 mg/mL) than for IV-CTA (400 mg/mL). Agreement between observers was acceptable (ICC=0.79±0.08).ConclusionOur feasibility study in swine showed that compared to IV-CTA, Selective-CTA provides better image quality and requires less iodine contrast medium.  相似文献   
77.
BackgroundThis study aimed to determine if sleep disturbances may mediate the relationship between panic symptoms and depression in patients with panic disorder (PD).MethodsElectronic medical records were retrospectively reviewed for 110 consecutive patients with diagnosed PD in an outpatient clinic between October 2018 and December 2019. Measurements include the PD Severity Scale, Beck Depression Inventory-II (BDI-II) and Insomnia Severity Index (ISI). Statistical analyses were performed to assess any potential relationship between PD, insomnia and depression.ResultsOf the PD patients, 88 (80%) and 89 (80.9%) had comorbid depression (BDI-II ≥ 14) and insomnia (Korean version of the ISI ≥ 8), respectively. In a mediation model using insomnia as the mediating variable, the total effect of panic symptom severity on depression was significant (t = 7.23, P < 0.001). There were significant effects of panic symptoms on insomnia (t = 4.62, P < 0.001) and of insomnia on depression (t = 6.69, P < 0.001). The main effect of panic symptom severity on depression was also significant, after controlling for the effect of insomnia (t = 5.10, P < 0.001), suggesting partial mediation.ConclusionBoth depressive symptoms and insomnia are common in patients with PD and depression was partially mediated by insomnia in these patients. These results suggest that an intervention for insomnia in patients with PD might help prevent the development of depression.  相似文献   
78.
Objective:This study investigated the usefulness of quantitative parameters [longitudinal relaxation (T1), transverse relaxation (T2), and proton density (PD)] obtained with synthetic magnetic resonance imaging (MRI) in assessing the progression of temporomandibular joint (TMJ) disorders.Methods:For individual TMJ disorder diagnoses, the presence of disc displacement in MRI and the osseous change in cone-beam CT were investigated. Joints were classified into three stages: (1) silent stage, no disc displacement or osseous change; (2) incipient stage, presence of disc displacement and absence of osseous change; and (3) progressed stage, both disc displacement and osseous change. In synthetic MRI, the T1, T2, and PD values of the condyle bone marrow were measured simultaneously. The median T1, T2, and PD values were analyzed according to disc displacement, osseous changes, and joint stage.Results:Significant differences were observed in the T1 and PD values of joints with disc displacement or condylar osseous change compared to normal joints. The T1 and PD values also differed between the silent and progressed stages. The PD value differed between the silent and incipient groups, while the T2 value did not differ significantly among the three groups.Conclusion:The PD and T1 values of condylar bone marrow obtained from synthetic MRI can be used as sensitive indicators of TMJ disorder progression. The PD value of the bone marrow showed potential as a useful biomarker for recognizing the initial stages of TMJ disorders. Synthetic MRI is useful for the simultaneous acquisition of effective MRI parameters for evaluating TMJ disorders.  相似文献   
79.
Compared with ST elevation myocardial infarction (STEMI), long-term outcomes are known to be worse in patients with unstable angina/non-STEMI (UA/NSTEMI), which might be related to the worse health status of patients with UA/STEMI. In patients with UA/NSTEMI and STEMI underwent percutaneous coronary intervention (PCI), angina-specific and general health-related quality-of-life (HRQOL) was investigated at baseline and at 30 days after PCI. Patients with UA/NSTEMI were older and had higher frequencies in female, diabetes and hypertension. After PCI, both angina-specific and general HRQOL scores were improved, but improvement was much more frequent in angina-related HRQOL of patients with UA/NSTEMI than those with STEMI (44.2% vs 36.8%, P < 0.001). Improvement was less common in general HRQOL. At 30-days after PCI, angina-specific HRQOL of the patients with UA/NSTEMI was comparable to those with STEMI (56.1 ± 18.6 vs 56.6 ± 18.7, P = 0.521), but general HRQOL was significantly lower (0.86 ± 0.21 vs 0.89 ± 0.17, P = 0.001) after adjusting baseline characteristics (P < 0.001). In conclusion, the general health status of those with UA/NSTEMI was not good even after optimal PCI. In addition to angina-specific therapy, comprehensive supportive care would be needed to improve the general health status of acute coronary syndrome survivors.  相似文献   
80.
The association of body mass index, smoking, and blood pressure, which are related to the three well-established risk factors of renal cell carcinoma, and survival in patients with renal cell carcinoma is not much studied. Our objective was to evaluate this association. A cohort of 1,036 patients with low stage (pT1 and pT2) renal cell carcinoma who underwent radical or partial nephrectomy were enrolled. We retrospectively reviewed medical records and collected survival data. The body mass index, smoking status, and blood pressure at the time of surgery were recorded. Patients were grouped according to their obesity grade, smoking status, and hypertension stage. Survival analysis showed a significant decrease in overall (P = 0.001) and cancer-specific survival (P < 0.001) with being underweight, with no differences of smoking status or perioperative blood pressure. On multivariate analysis, perioperative blood pressure ≥ 160/100 mmHg (HR, 2.642; 95% CI, 1.221-5.720) and being underweight (HR, 4.320; 95% CI, 1.557-11.984) were independent predictors of overall and cancer-specific mortality, respectively. Therefore, it is concluded that being underweight and perioperative blood pressure ≥ 160/100 mmHg negatively affect cancer-specific and overall survival, respectively, while smoking status does not influence survivals in patients with renal cell carcinoma.  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