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   4349篇
  免费   246篇
  国内免费   37篇
耳鼻咽喉   67篇
儿科学   96篇
妇产科学   53篇
基础医学   592篇
口腔科学   111篇
临床医学   497篇
内科学   829篇
皮肤病学   34篇
神经病学   354篇
特种医学   183篇
外科学   807篇
综合类   71篇
一般理论   2篇
预防医学   278篇
眼科学   79篇
药学   332篇
中国医学   11篇
肿瘤学   236篇
  2022年   36篇
  2021年   62篇
  2019年   45篇
  2018年   66篇
  2017年   46篇
  2016年   55篇
  2015年   78篇
  2014年   106篇
  2013年   166篇
  2012年   199篇
  2011年   199篇
  2010年   105篇
  2009年   124篇
  2008年   181篇
  2007年   196篇
  2006年   184篇
  2005年   224篇
  2004年   189篇
  2003年   171篇
  2002年   165篇
  2001年   165篇
  2000年   144篇
  1999年   138篇
  1998年   53篇
  1997年   42篇
  1996年   39篇
  1995年   37篇
  1993年   29篇
  1992年   102篇
  1991年   80篇
  1990年   82篇
  1989年   80篇
  1988年   74篇
  1987年   75篇
  1986年   49篇
  1985年   65篇
  1984年   50篇
  1983年   33篇
  1982年   37篇
  1981年   35篇
  1980年   34篇
  1979年   38篇
  1978年   35篇
  1976年   32篇
  1975年   28篇
  1974年   32篇
  1973年   33篇
  1972年   31篇
  1971年   36篇
  1970年   28篇
排序方式: 共有4632条查询结果,搜索用时 15 毫秒
101.
Human herpesvirus type 6-(HHV-6) has been associated with morbidity after liver transplantation.ObjectiveThe aim of this study was to determine the HHV-6 seroprevalence among donorrecipient pairs, analyze the incidence of early active infection, its clinical manifestation, interaction with CMV, and the related morbidity in the first year after kidney transplantation.Methods46 donor-recipient pairs had IgG evaluated by ELISA before transplantation: HHV-6-(Pambio – USA) and CMV-(Roche – USA). A frozen whole blood sample collected weekly (from the 1st to the 6th week) was retrospectively tested for HHV-6 viral load (VL) determination by real time quantitative PCR (qPCR, Nanogen – Italy). Patients were preemptively surveyed for CMV by pp65 antigenemia (Ag, APAAP, immunohistochemistry, Biotest – Germany) from the 4th to the 12th week after transplantation. Active infection was defined as qPCR-HHV6+ (viral-load/mL-VL) and Ag+ (+cells/100.000 granulocytes), for HHV-6 and CMV, respectively. DCMV was defined as simultaneous positive antigenemia and suggestive signs/symptoms. Concerning +qPCR-HHV6, associated factors, clinical manifestation, interaction with CMV and morbidity were searched.ResultsPre-transplant HHV-6 seroprevalence was significantly higher among kidney recipients compared to their donors (82.6×54.8%; p = 0.005 [3.9 (1.4–10.4)]). Active infection by this virus occurred in 26.1% (12/46), with no association with previous IgG (p = 0.412). Median VL was 125 copies/mL (53–11.264), and the median Ag was 21 +cells (2–740). There was no association between HHV-6 and CMV activation after transplantation (p = 0.441), neither concerning DCMV (p = 0.596). Median highest Ag+ and days of ganciclovir treatment were similar between qPCR-HHV6 + or ? (p = 0.206 and p = 0.124, respectively). qPCR-HHV6+ was associated with higher incidence of bacterial (p = 0.009) and fungal (p = 0.001) infections, and higher number (p = 0.001) of hospital admission and longer duration of hospitalization over the first 6 and 12 months post-transplantation (p = 0.033 and p = 0.001).ConclusionLatent HHV-6 infection is more common among recipients than donors before transplantation. Early active infection by this pathogen after transplantation does not increase DCMV incidence or severity during the first 3 months of follow-up. However, early HHV-6 replication is associated with other infections and hospitalizations in the first year.  相似文献   
102.
Delayed cerebral ischemia remains a severe potential complication of aneurysmal subarachnoid hemorrhage (SAH) possibly leading to death and disability. We evaluated a semiquantitative and visual analysis of perfusion computed tomography (PCT) as a predictor of clinically relevant vasospasm (CRV) in patients with aneurysmal SAH. Thirty-eight patients with aneurysmal SAH were analyzed yielding 145 PCT scans. PCT, clinical examination, and transcranial Doppler ultrasound (TCD) were performed on days 3, 7, 10, and 14 after hemorrhage. Cerebral blood flow, cerebral blood volume, and time to peak (TTP) were analyzed semiquantitatively using six regions of interest, and visually for signs of cerebral hypoperfusion. CRV was defined as secondary cerebral infarction (CI) seen on cranial computed tomography scans and/or delayed neurological deterioration (DND). CI occurred in 13 (34.2 %) and DND in 11 patients (28.9 %). With TCD as pretest, TTP had a sensitivity of 90 % and a specificity of 72 % (cutoff value, 0.963) as predictor for CI. TTP’s sensitivity as predictor for DND was 90 % with a specificity of 61.1 % (cutoff value, 0.983). Visual analysis of TTP showed a negative predictive value of 100 % with a positive predictive value of 52 %. TTP is a sensitive and specific perfusion parameter in predicting CI in patients with SAH. Its use in the clinical setting may optimize the early treatment of patients at risk for vasospasm before the onset of clinical deterioration, especially when applying TCD as pretest. Further investigation in a larger patient population is required.  相似文献   
103.
104.
105.
106.
Intestinal types of adenocarcinoma of the inner nose and colorectal adenocarcinoma present a stupendous similarity of morphological and immunohistochemical features. The previously unpublished observation of a synchronous manifestation of both adenocarcinoma enabled us to compare the tumors using molecular and immunohistochemical methods. Polymerase chain reaction was performed in order to investigate microsatellite instability. Mutation of p53 and K-ras was examined by direct DNA sequencing. Chromosomal imbalances were investigated by comparative genomic hybridization. Histology and immunohistochemical reactions were nearly identical. PCR results revealed no microsatellite instability or loss of heterozygosity in any of the tumors. A p53 mutation in exon 5 could be detected in the colon tumor but not in the sinonasal carcinoma, while a K-ras mutation was only present in the tumor of the inner nose. The comparative genomic hybridization method revealed different chromosomal imbalances in the different tumors. Thus, the molecular pathologic data proved the presence of 2 independent primary adenocarcinomas of the intestinal type.  相似文献   
107.
108.
Smoking is much more common among persons with behavioral health conditions (mental illnesses and/or substance use disorders). Persons with these disorders are more likely to die from smoking-related causes than any other reason. Studies have shown that stopping smoking can improve mental health function, as well as improve outcomes for substance use disorders. Yet, for a variety of reasons, smoking cessation has not been integrated into the treatment of behavioral health conditions, and in many instances tobacco use was not only condoned but encouraged. Beginning in 2007, the Smoking Cessation Leadership Center (SCLC) began engaging relevant agencies in an attempt to stimulate more vigorous smoking cessation activities. Partners included the federal Substance Abuse and Mental Health Services Administration, advocacy organizations such as the National Alliance on Mental Illness and Community Anti-Drug Coalitions of America, and clinical groups such as the American Psychiatric Nurses Association, the American Psychiatric Association, American Psychological Association, National Council on Behavioral Health, and National Association of State Mental Health Program Directors. A signature program featured 16 individual state summits involving agencies and groups from multiple sectors, all aiming to lower smoking rates in behavioral health populations. These activities mark an evolving culture change within behavioral health.  相似文献   
109.
Early access to care is essential to improve survival rates for childhood cancer. This study evaluates the determinants of delays in childhood cancer care in low- and middle-income countries (LMICs) through a systematic review of the literature. We proposed a novel Three-Delay framework specific to childhood cancer in LMICs by summarizing 43 determinants and 24 risk factors of delayed cancer care from 95 studies. Traditional medicine, household income, lack of transportation, rural population, parental education, and travel distance influenced most domains of our framework. Our novel framework can be used as a policy tool toward improving cancer care and outcomes for children in LMICs.  相似文献   
110.
Neurosurgical Review - Indications for surgery of pineal cysts without ventriculomegaly are still under debate. In view of the limited data for pineal cyst resection in the absence of...  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