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   4343973篇
  免费   349434篇
  国内免费   14147篇
耳鼻咽喉   61208篇
儿科学   139860篇
妇产科学   115042篇
基础医学   665970篇
口腔科学   118466篇
临床医学   392831篇
内科学   786708篇
皮肤病学   110680篇
神经病学   361513篇
特种医学   168133篇
外国民族医学   616篇
外科学   666472篇
综合类   119820篇
现状与发展   23篇
一般理论   2619篇
预防医学   364494篇
眼科学   101901篇
药学   306440篇
  21篇
中国医学   11522篇
肿瘤学   213215篇
  2021年   52921篇
  2020年   37233篇
  2019年   61693篇
  2018年   78815篇
  2017年   59365篇
  2016年   65413篇
  2015年   78499篇
  2014年   113592篇
  2013年   180617篇
  2012年   135242篇
  2011年   141676篇
  2010年   131449篇
  2009年   131335篇
  2008年   125510篇
  2007年   133976篇
  2006年   141460篇
  2005年   136359篇
  2004年   135557篇
  2003年   124885篇
  2002年   113544篇
  2001年   152864篇
  2000年   147341篇
  1999年   135322篇
  1998年   64869篇
  1997年   60789篇
  1996年   58876篇
  1995年   59490篇
  1994年   53655篇
  1993年   49866篇
  1992年   97637篇
  1991年   94423篇
  1990年   90693篇
  1989年   88263篇
  1988年   81360篇
  1987年   79855篇
  1986年   75143篇
  1985年   74085篇
  1984年   62246篇
  1983年   55785篇
  1982年   45935篇
  1981年   42966篇
  1980年   40331篇
  1979年   53629篇
  1978年   44278篇
  1977年   39003篇
  1976年   36370篇
  1975年   36565篇
  1974年   39956篇
  1973年   38227篇
  1972年   35937篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
71.
72.
Journal of Neuro-Oncology - Adjuvant radiation is often used in patients with low grade gliomas with high-risk characteristics with a recommended dose of 45–54 Gy. We used the...  相似文献   
73.
The authors define molecular imaging, according to the Society of Nuclear Medicine and Molecular Imaging, as the visualization, characterization, and measurement of biological processes at the molecular and cellular levels in humans and other living systems. Although practiced for many years clinically in nuclear medicine, expansion to other imaging modalities began roughly 25 years ago and has accelerated since. That acceleration derives from the continual appearance of new and highly relevant animal models of human disease, increasingly sensitive imaging devices, high-throughput methods to discover and optimize affinity agents to key cellular targets, new ways to manipulate genetic material, and expanded use of cloud computing. Greater interest by scientists in allied fields, such as chemistry, biomedical engineering, and immunology, as well as increased attention by the pharmaceutical industry, have likewise contributed to the boom in activity in recent years. Whereas researchers and clinicians have applied molecular imaging to a variety of physiologic processes and disease states, here, the authors focus on oncology, arguably where it has made its greatest impact. The main purpose of imaging in oncology is early detection to enable interception if not prevention of full-blown disease, such as the appearance of metastases. Because biochemical changes occur before changes in anatomy, molecular imaging—particularly when combined with liquid biopsy for screening purposes—promises especially early localization of disease for optimum management. Here, the authors introduce the ways and indications in which molecular imaging can be undertaken, the tools used and under development, and near-term challenges and opportunities in oncology.  相似文献   
74.
The use of radiation for primary liver cancers has historically been limited because of the risk of radiation-induced liver disease. Treatment fields have become more conformal because of several technical advances, and this has allowed for dose escalation. Stereotactic body radiation therapy (SBRT), also known as stereotactic ablative radiotherapy, is now able to safely treat liver tumors to ablative doses while sparing functional liver parenchyma by using highly conformal therapy. Several retrospective and small prospective studies have examined the use of SBRT for liver cancers; however, there is a lack of well-powered randomized studies to definitively guide management in these settings. Recent advances in systemic therapy for primary liver cancers have improved outcomes; however, the optimal selection criteria for SBRT as a local therapy remain unclear among other liver-directed options such as radiofrequency ablation, transarterial chemoembolization, and radioembolization.  相似文献   
75.
TP53 is the most frequently mutated gene in head and neck squamous cell carcinoma (HNSCC). Patients with HPV-negative TP53 mutant HNSCC have the worst prognosis, necessitating additional agents for treatment. Since mutant p53 causes sustained activation of the PI3K/AKT/mTOR signaling pathway, we investigated the effect of rapalogs RAD001 and CCI-779 on HPV-negative mutTP53 HNSCC cell lines and xenografts. Rapalogs significantly reduced cell viability and colony formation. Interestingly, rapalogs-induced autophagy with no effect on apoptosis. Pretreatment with autophagy inhibitors, 3-methyladenine (3-MA) and ULK-101 rescued the cell viability by inhibiting rapalog-induced autophagy, suggesting that both RAD001 and CCI-779 induce non-apoptotic autophagy-dependent cell death (ADCD). Moreover, rapalogs upregulated the levels of ULK1 and pULK1 S555 with concomitant downregulation of the mTORC1 pathway. However, pretreatment of cells with rapalogs prevented the ULK-101-mediated inhibition of ULK1 to sustained autophagy, suggesting that rapalogs induce ADCD through the activation of ULK1. To further translate our in vitro studies, we investigated the effect of RAD001 in HPV-negative mutTP53 (HN31 and FaDu) tumor cell xenograft model in nude mice. Mice treated with RAD001 exhibited a significant tumor volume reduction without induction of apoptosis, and with a concomitant increase in autophagy. Further, treatment with RAD001 was associated with a considerable increase in pULK1 S555 and ULK1 levels through the inhibition of mTORC1. 3-MA reversed the effect of RAD001 on FaDu tumor growth suggesting that RAD001 promotes ACDC in HPV-negative mutTP53 xenograft. This is the first report demonstrating that rapalogs promote non-apoptotic ADCD in HPV-negative mutTP53 HNSCC via the ULK1 pathway. Further studies are required to establish the promising role of rapalogs in preventing the regrowth of HPV-negative mutTP53 HNSCC.  相似文献   
76.
PurposeAnaerobic infections are common yet life-threatening. They are being recovered from all sites of the body, including the cardiovascular system. This study was aimed to determine the retrospective analysis on the isolation of anaerobes in cardiovascular samples received for a decade-long duration. It helps in knowing the frequency of isolation of anaerobic causes of cardiovascular infection.MethodsAll cardiovascular samples from the department of Cardio-thoracic vascular surgery from January 2010 to December 2020 were studied.ResultsOf 601 samples received, predominant samples were vegetations and valvular tissues of 258, followed by 98 samples of pericardial tissues, 92 samples of embolus, 90 samples of blood and post-operative collections, and 63 excised aneurysms and vascular grafts. Of the total, 15 samples grew anaerobes where Clostridium species were the predominant isolates. Clostridioides difficile was isolated in 2 samples.ConclusionsAnaerobes in cardiovascular samples are uncommon yet form a significant cause of morbidity and mortality. Most infections are from the contiguous spread, penetrating trauma, and hematogenous causing endocarditis or valvular infections. These conditions and samples form the seat of infectious focus and clinical suspicion towards the anaerobic cause of these conditions, especially in conventional routine culture-negative samples. Timely diagnosis of anaerobic infections plays a vital role in the good prognostic outcome of patients undergoing cardiothoracic and vascular surgery.  相似文献   
77.
Biomedical Engineering - The possible use of the vortex effect in medical transfusion–infusion solution heaters was studied. A design for a device is presented, along with the trial results....  相似文献   
78.
79.
Hormone receptor (HR)-positive and human epidermal growth factor receptor 2 (HER2)-negative breast cancer is defined by the presence of the estrogen receptor and/or the progesterone receptor and the absence of HER2 gene amplification. HR-positive/HER2-negative breast cancer accounts for 65%–70% of all breast cancers, and incidence increases with increasing age. Treatment varies by stage, and endocrine therapy is the mainstay of treatment in both early stage and late-stage disease. Combinations with cyclin-dependent kinase 4/6 inhibitors have reduced distant recurrence in the early stage setting and improved overall survival in the metastatic setting. Chemotherapy is used based on stage and tumor biology in the early stage setting and after endocrine resistance for advanced disease. New therapies, including novel endocrine agents and antibody-drug conjugates, are now changing the treatment landscape. With the availability of new treatment options, it is important to define the optimal sequence of treatment to maximize clinical benefit while minimizing toxicity. In this review, the authors first discuss the pathologic and molecular features of HR-positive/HER2-negative breast cancer and mechanisms of endocrine resistance. Then, they discuss current and emerging therapies for both early stage and metastatic HR-positive/HER2-negative breast cancer, including treatment algorithms based on current data.  相似文献   
80.
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