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   225798篇
  免费   12324篇
  国内免费   6343篇
耳鼻咽喉   2802篇
儿科学   8348篇
妇产科学   2987篇
基础医学   16798篇
口腔科学   4186篇
临床医学   27008篇
内科学   41683篇
皮肤病学   3050篇
神经病学   10843篇
特种医学   12364篇
外国民族医学   22篇
外科学   33171篇
综合类   20596篇
现状与发展   25篇
预防医学   16344篇
眼科学   4423篇
药学   24096篇
  86篇
中国医学   4543篇
肿瘤学   11090篇
  2023年   1956篇
  2022年   3946篇
  2021年   9178篇
  2020年   5532篇
  2019年   11383篇
  2018年   5994篇
  2017年   5029篇
  2016年   7066篇
  2015年   9994篇
  2014年   18228篇
  2013年   15869篇
  2012年   19337篇
  2011年   16222篇
  2010年   14733篇
  2009年   14307篇
  2008年   12848篇
  2007年   12970篇
  2006年   10896篇
  2005年   7202篇
  2004年   3602篇
  2003年   3200篇
  2002年   2564篇
  2001年   2053篇
  2000年   1828篇
  1999年   1200篇
  1998年   1528篇
  1997年   1359篇
  1996年   1145篇
  1995年   1213篇
  1994年   1170篇
  1993年   894篇
  1992年   1107篇
  1991年   995篇
  1990年   1045篇
  1989年   1022篇
  1988年   941篇
  1987年   835篇
  1986年   673篇
  1985年   1584篇
  1984年   1736篇
  1983年   1253篇
  1982年   1338篇
  1981年   1325篇
  1980年   1149篇
  1979年   984篇
  1978年   756篇
  1977年   759篇
  1976年   664篇
  1974年   455篇
  1973年   433篇
排序方式: 共有10000条查询结果,搜索用时 16 毫秒
21.
【目的】 在“中国科技期刊卓越行动计划”实施三周年之际,有必要对我国科技期刊2035年迈入“世界第一方阵”目标的具体任务进行重新审视和预判,以进一步明确发展方向,动态调整推进思路。【方法】 采用国内外科技期刊、科技论文、科技期刊评价成果的系统性发展数据对科技期刊“世界第一方阵” 国家(或地区)在高水平科技期刊数量与质量层面的入围标准进行界定,在深入总结现有基础和优势的同时,对我国科技期刊综合实力与“世界第一方阵”国家(或地区)的现实差距进行逐一梳理和剖析,并对实现目标的可行性和推进思路进行研判和设计。【结果】 必须继续加强高水平英文科技期刊创办和培育力度、持续加大优秀中文科技期刊的建设强度、快速推进国内外科技期刊论文等质同效评价制度的建设与引导,并积极探索建立科学家和科研机构办好一流科技期刊的责任制度和贡献激励机制、创新发展编辑人才队伍培养与激励管理思路、深入实践灵活多样的期刊出版市场资本运作模式、稳步推进期刊出版市场机制和管理制度改革,为我国科技期刊事业的高质量发展提速增效。【结论】 虽然当前阶段目标任务艰巨,但迈入“世界第一方阵”未来可期。  相似文献   
22.
《Clinical breast cancer》2022,22(6):507-514
Breast cancer (BC) is a highly metastatic, pathological cancer that significantly affects women worldwide. The mortality rate of BC is related to its heterogeneity, aggressive phenotype, and metastasis. Recent studies have highlighted that the tumor microenvironment (TME) is critical for the interplay between metastasis mediators in BC. BC stem cells, tumor-derived exosomes, circulatory tumor cells (CTCs), and signaling pathways dynamically remodel the TME and promote metastasis. This review examines the cellular and molecular mechanisms governing the epithelial to mesenchymal transition (EMT) that facilitate metastasis. This review also discusses the role of cancer stem cells (CSCs), tumor-derived exosomes, and CTs in promoting BC metastasis. Furthermore, the review emphasizes major signaling pathways that mediate metastasis in BC. Finally, the interplay among CSCs, exosomes, and CTCs in mediating metastasis have been highlighted. Therefore, understanding the molecular cues that mediate the association of CSCs, exosomes, and CTCs in TME helps to optimize systemic therapy to target metastatic BC.  相似文献   
23.
Actinomycosis is a rare, indolent and invasive infection caused by Actinomyces species. Actinomycosis develops when there is disruption of the mucosal barrier, and invasion and systemic spread of the organism, which can lead to endogenous infection affecting numerous organs. It is known to spread in tissue through fascial planes and most often involves the cervicofacial (55%), abdominopelvic (20%) and thoracic (15%) soft tissue. Pulmonary actinomycosis is rare in patients under the age of five years, with the median reported age in the fifth decade. Clinical findings include chest wall mass (49%), cough (40%), pain (back, chest, shoulders) (36%), weight loss (19%), fever (19%), Draining sinuses (15%) and hemoptysis (9%). Chest x-ray findings in pulmonary actinomycosis are mostly nonspecific and can overlap with pulmonary tuberculosis, foreign body aspiration and malignancy. Endobronchial tissue aggregates may show sulphur granules, with yellow to white conglomerate areas of gram positive Actinomyces. Removal or biopsy of these large endobronchial masses must be done with care, because of the risk of bleeding and large airway obstruction. The cytology on bronchoalveolar lavage fluid may show Periodic acid–Schiff (PAS) positive stain, ZN negative and Gram-positive filamentous bacilli which is morphologically suggestive of Actinomycosis. Actinomyces spp is highly susceptible to beta lactam antibiotics, penicillin G, and amoxicillin. A minimum of 3–6 months is needed but up to 20 months of treatment may be needed. Early diagnosis and correct treatment can lead to a good prognosis with a low mortality.  相似文献   
24.
25.
PurposeTo test the following hypotheses: (a) balloon or stent assistance increases coil packing density (CPD) in the endovascular treatment of intracranial aneurysms, and (b) CPD correlates to ostium area (OA) and aneurysm volume (AV).Materials and MethodsThis retrospective study included 60 aneurysms (54 ruptured and 6 unruptured) treated with simple coiling (SC) (n = 18), balloon-assisted coiling (BAC) (n = 7), or stent-assisted coiling (SAC) (n = 35) at the authors’ institution between August 2017 and December 2019. AV and OA measurements were obtained from 3-dimensional digital subtraction angiography images using commercial software. Coil sizes were retrieved from patient files, and coil volume (CV) measurements were obtained from https://www.angiocalc.com/. Analysis of covariance, multivariate covariance analysis, and Pearson correlation analyses were performed.ResultsThe median value for AV, CV, CPD, and OA was 63.4 mm3 (range, 5.5–1,771.4 mm3), 23.13 mm3 (range, 2.03–296.95 mm3), 33.29% (range, 13.41%–81.02%), and 10.7 mm2 (range, 2.7–49.9 mm2), respectively. Multivariate analysis showed that the CPD values were not significantly different among the treatment groups, although OA significantly differed between the SC and SAC groups (P < .05). Pearson correlations showed that similar to AV, OA was negatively correlated with CPD (r = ?0.321, P < .05).ConclusionsThe CPD value in cerebral aneurysms treated with BAC or SAC did not differ from that in aneurysms treated with SC.  相似文献   
26.
PurposeTo evaluate the efficacy and safety of microwave (MW) ablation as first-line locoregional therapy (LRT) for bridging patients with hepatocellular carcinoma (HCC) to liver transplant.Materials and MethodsThis retrospective study evaluated 88 patients who received percutaneous MW ablation for 141 tumors as first-line LRT for HCC and who were listed for liver transplantation at a single medical center between 2011 and 2019. The overall survival (OS) rate statuses after liver transplant, waitlist retention, and disease progression were evaluated using the Kaplan-Meier techniques.ResultsAmong the 88 patients (72 men and 16 women; mean age, 60 years; Model for End-Stage Liver Disease score, 11.2) who were listed for transplant, the median waitlist time was 9.4 months (interquartile range, 5.5–18.9). Seventy-one (80.7%) patients received transplant after a median waitlist time of 8.5 months. Seventeen (19.3%) patients were removed from the waitlist; of these, 4 (4.5%) were removed because of tumors outside of the Milan criteria (HCC-specific dropout). No difference in tumor size or alpha-fetoprotein was observed in the transplanted versus nontransplanted patients at the time of ablation (2.1 vs 2.1 cm and 34.4 vs 34.7 ng/mL for transplanted vs nontransplanted, respectively; P > .05). Five (5.1%) of the 88 patients experienced adverse events after ablation; however, they all recovered. There were no cases of tract seeding. The local tumor progression (LTP) rate was 7.2%. The OS status after liver transplant at 5 years was 76.7%, and the disease-specific survival after LTP was 89.6%, with a median follow-up of 61 months for all patients.ConclusionsMW ablation appears to be safe and effective for bridging patients with HCC to liver transplant without waitlist removal from seeding, adverse events, or LTP.  相似文献   
27.
28.
《Vaccine》2022,40(52):7515-7519
The recent wave of COVID-19 cases has led to the potential need for booster doses. We surveyed 6,294 people and found that 87.6% reported willingness to take a booster dose, with vaccine efficacy rate being the most common reason cited to accept booster dose. Differences in acceptance rates were noted among those working in non-health related sectors, different ethnic groups as well as those who had taken viral vector vaccines.  相似文献   
29.
30.
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