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   67777篇
  免费   5796篇
  国内免费   1322篇
耳鼻咽喉   301篇
儿科学   1120篇
妇产科学   947篇
基础医学   6257篇
口腔科学   385篇
临床医学   6629篇
内科学   8703篇
皮肤病学   528篇
神经病学   1593篇
特种医学   3278篇
外国民族医学   24篇
外科学   6194篇
综合类   9468篇
现状与发展   3篇
一般理论   2篇
预防医学   4275篇
眼科学   771篇
药学   5564篇
  35篇
中国医学   2271篇
肿瘤学   16547篇
  2024年   92篇
  2023年   1055篇
  2022年   2002篇
  2021年   2958篇
  2020年   2420篇
  2019年   2793篇
  2018年   2806篇
  2017年   2653篇
  2016年   2397篇
  2015年   2495篇
  2014年   5918篇
  2013年   5286篇
  2012年   4243篇
  2011年   4577篇
  2010年   3828篇
  2009年   3692篇
  2008年   3600篇
  2007年   3060篇
  2006年   2525篇
  2005年   2084篇
  2004年   1837篇
  2003年   1619篇
  2002年   1236篇
  2001年   1218篇
  2000年   1079篇
  1999年   900篇
  1998年   732篇
  1997年   664篇
  1996年   584篇
  1995年   545篇
  1994年   504篇
  1993年   357篇
  1992年   318篇
  1991年   250篇
  1990年   221篇
  1989年   227篇
  1988年   179篇
  1987年   148篇
  1986年   118篇
  1985年   219篇
  1984年   231篇
  1983年   164篇
  1982年   203篇
  1981年   162篇
  1980年   164篇
  1979年   119篇
  1978年   96篇
  1977年   67篇
  1976年   63篇
  1974年   53篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
《Cancer radiothérapie》2022,26(4):611-615
In order to provide more convenient irradiation regimens for patient comfort, radiation facility organization and health expenses, new hypofractionated protocols have been evaluated. Moderately (dose/fraction: 2.3 to 3 Gy), then ultra (dose/fraction: 5.2 to 6.1 Gy) hypofractionated irradiations were first validated. The current question is: is it possible to go forward using extreme hypofractionated regimens (EHR) based on 1 to 3 fractions. Different irradiation techniques are under investigation. However, brachytherapy remains the smartest way to deliver a high dose in a small volume. We report prospective and retrospective study results which evaluated EHR for breast and prostate brachytherapy. While oncological outcome and toxicity profile appear extremely encouraging for low-risk breast cancer after a 1 to 4 fractions (6.25 to 20 Gy/fraction), the use of a single fraction of 19 to 23 Gy appears debatable for prostate cancer. Brachytherapy represents an emblematic example of EHR but longer follow-up and more mature results are awaited in order to specify the right indications and refine the EQD2 calculation method including new biological and technical factors.  相似文献   
2.
3.
4.
ObjectiveEach pulmonary segment is an anatomical and functional unit. However, it is fundamentally difficult to precisely distinguish every pulmonary segment using the conventional pulmonary intersegmental planes from computed tomography images. Building arteriopulmonary segments is likely to be an effective way to identify pulmonary segments.MethodsThe thoracic computed tomography images of 40 patients were collected. The anatomic structures of interest were extracted in the transverse, sagittal, and coronal planes using the semi-automated segmentation tools provided by Amira software. The intrapulmonary vessels were subsequently segmented and reconstructed. The distributions of the pulmonary arteries, veins, and bronchi were observed. In patients with pulmonary masses, the mass was also reconstructed.ResultsThe three-dimensional reconstructed images showed the branches of the pulmonary artery ramified up to their eighth order covering the entire lung as well as evident intersegmental gaps without pulmonary arteries. The segmental artery was closely accompanied by the segmental bronchi in 486 pulmonary segments (90% of total number of segments). The size and spatial location of the pulmonary mass within a pulmonary segment were also clearly visible.ConclusionsDemarcation of arteriopulmonary segments can be used to precisely distinguish every pulmonary segment and provide its detailed anatomical structure before pulmonary segmentectomy.  相似文献   
5.
6.
AimLung metastases are a negative prognostic factor in Ewing sarcoma, however, the incidence and significance of sub-centimetre pulmonary nodules at diagnosis is unclear. The aims of this study were to (1): determine the incidence of indeterminate pulmonary nodules (IPNs) in patients diagnosed with Ewing sarcoma (2); establish the impact of IPNs on overall and metastasis-free survival and (3) identify patient, oncological and radiological factors that correlate with poorer prognosis in patients that present with IPNs on their staging chest CT.Materials & methodsBetween 2008 and 2016, 173 patients with a first presentation of Ewing sarcoma of bone were retrospectively identified from an institutional database. Staging and follow-up chest CTs for all patients with IPN were reviewed by a senior radiologist. Clinical and radiologic course were examined to determine overall- and metastasis-free survival for IPN patients and to identify demographic, oncological or nodule-specific features that predict which IPN represent true lung metastases.ResultsFollowing radiologic re-review, IPN were found in 8.7% of patients. Overall survival for IPN patients was comparable to those with a normal staging chest CT (2-year overall survival of 73.3% [95% CI 43.6–89] and 89.4% [95% CI 81.6–94], respectively; p = 0.34) and was significantly better than for patients with clear metastases (46.0% [95% CI 31.9–59]; p < 0.0001). Similarly, there was no difference in metastasis-free survival between ‘No Metastases’ and ‘IPN’ patients (p = 0.16). Lung metastases developed in 40% of IPN patients at a median 9.6 months. Reduction of nodule size on neoadjuvant chemotherapy was associated with worse overall survival in IPN patients (p = 0.0084).ConclusionIPN are not uncommon in patients diagnosed with Ewing sarcoma. In this study, we were unable to detect a difference in overall- or metastasis-free survival between patients with IPN at diagnosis and patients with normal staging chest CTs.  相似文献   
7.
The COVID-19 pandemic caused by the SARS-CoV-2 virus has significantly disrupted and burdened the diagnostic workup and delivery of care, including transfusion, to cancer patients across the globe. Furthermore, cancer patients suffering from solid tumors or hematologic malignancies were more prone to the infection and had higher morbidity and mortality than the rest of the population. Major signaling pathways have been identified at the intersection of SARS-CoV-2 and cancer cells, often leading to tumor progression or alteration of the tumor response to therapy. The reactivation of oncogenic viruses has also been alluded to in the context and following COVID-19. Paradoxically, certain tumors responded better following the profound infection-induced immune modulation. Unveiling the mechanisms of the virus-tumor cell interactions will lead to a better understanding of the pathophysiology of both cancer progression and virus propagation. It would be challenging to monitor, through the different cancer registries, retrospectively, the response of patients who have been previously exposed to the virus in contrast to those who have not contracted the infection.  相似文献   
8.
Background: Thyrosin kinase inhibitors (TKIs) is approved for the first line treatment of non-small cell lung cancer (NSCLC) patients with  epidermal growth factor receptor (EGFR) mutation. This study performed to assess clinical effectiveness and safety of Erlova (generic form of Erlotinib). Methods: Somatic mutations of EGFR gene were studied in tumor tissue by polymerase chain reaction (PCR) and bi-directional sequencing in 513 chemonaive and histologically verified lung adenocarcinoma Iranian patients. Patients  with EGFR mutation received Erlova at 150 mg/day  as first line treatment. Primary endpoint was progression free survival (PFS). Results: About 21% (n=109) cases had EGFR mutation. Most EGFR mutations were  occurred at exon 19. Among them, sixty nine patients treated with Erlova. Median PFS was 11.4 months and objective response rate (ORR) was about  88%. Most frequent treatment related adverse events was  skin rash. Conclusion: Our findings showed Erlova had remarkable effectiveness. In  mutation-positive patients with EGFR, Erlova can be used  safely instead of  other tyrosine-kinase inhibitors.  相似文献   
9.
10.
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