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   38283篇
  免费   4260篇
  国内免费   2987篇
耳鼻咽喉   426篇
儿科学   348篇
妇产科学   303篇
基础医学   3715篇
口腔科学   615篇
临床医学   4833篇
内科学   4933篇
皮肤病学   464篇
神经病学   1702篇
特种医学   1651篇
外国民族医学   11篇
外科学   4760篇
综合类   8052篇
现状与发展   14篇
一般理论   2篇
预防医学   2997篇
眼科学   870篇
药学   4290篇
  34篇
中国医学   2696篇
肿瘤学   2814篇
  2024年   208篇
  2023年   853篇
  2022年   2013篇
  2021年   2438篇
  2020年   1930篇
  2019年   1446篇
  2018年   1466篇
  2017年   1446篇
  2016年   1281篇
  2015年   1958篇
  2014年   2320篇
  2013年   2412篇
  2012年   3211篇
  2011年   3480篇
  2010年   2518篇
  2009年   2042篇
  2008年   2241篇
  2007年   2199篇
  2006年   1933篇
  2005年   1783篇
  2004年   1163篇
  2003年   964篇
  2002年   821篇
  2001年   626篇
  2000年   564篇
  1999年   527篇
  1998年   256篇
  1997年   260篇
  1996年   214篇
  1995年   187篇
  1994年   156篇
  1993年   77篇
  1992年   90篇
  1991年   86篇
  1990年   81篇
  1989年   58篇
  1988年   54篇
  1987年   35篇
  1986年   28篇
  1985年   11篇
  1984年   17篇
  1982年   11篇
  1981年   10篇
  1979年   6篇
  1978年   11篇
  1977年   5篇
  1975年   4篇
  1974年   4篇
  1973年   4篇
  1972年   7篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
101.
BackgroundThe selective pressure imposed by chemotherapy creates a barrier to tumor eradication and an opportunity for metastasis and recurrence. As a newly discovered stemness marker of pancreatic ductal adenocarcinoma (PDAC), the impact of CD9 on tumor progression and patient''s prognosis remain controversial.MethodsA total of 179 and 211 PDAC patients who underwent surgical resection with or without neoadjuvant chemotherapy, respectively, were recruited for immunohistochemical analyses of CD9 expression in both tumor and stromal areas prior to statistical analyses to determine the prognostic impact and predictive accuracy of CD9.ResultsThe relationship between CD9 and prognostic indicators was not significant in the non‐neoadjuvant group. Nevertheless, CD9 expression in both tumor (T‐CD9) and stromal areas (S‐CD9) was significantly correlated with the clinicopathological features in the neoadjuvant group. High levels of T‐CD9 were significantly associated with worse OS (p = 0.005) and RFS (p = 0.007), while positive S‐CD9 showed the opposite results (OS: p = 0.024; RFS: p = 0.008). Cox regression analyses identified CD9 in both areas as an independent prognostic factor. The T&S‐CD9 risk‐level system was used to stratify patients with different survival levels. The combination of T&S‐CD9 risk level and TNM stage were accurate predictors of OS (C‐index: 0.676; AIC: 512.51) and RFS (C‐index: 0.680; AIC: 519.53). The calibration curve of the nomogram composed of the combined parameters showed excellent predictive consistency for 1‐year RFS. These results were verified using a validation cohort.ConclusionNeoadjuvant chemotherapy endows CD9 with a significant prognostic value that differs between tumor and stromal areas in patients with pancreatic cancer.  相似文献   
102.
BackgroundThe spread of COVID‐19 worldwide caused by the severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) has necessitated efficient, sensitive diagnostic methods to identify infected people. We report on the development of a rapid 15‐minute time‐resolved fluorescent (TRF) lateral flow immunochromatographic assay for the quantitative detection of the SARS‐CoV‐2 spike protein receptor‐binding domain (S1‐RBD).ObjectivesOur objective was to develop an efficient method of detecting SARS‐CoV‐2 within 15 min of sample collection.MethodsWe constructed and evaluated a portable, disposable lateral flow device, which detected the S1‐RBD protein directly in nasopharyngeal swab samples. The device emits a fluorescent signal in the presence of S1‐RBD, which can be captured by an automated TRF instrument.ResultsThe TRF lateral flow assay signal was linear from 0 to 20 ng/ml and demonstrated high accuracy and reproducibility. When evaluated with clinical nasopharyngeal swabs, the assay was performed at >80% sensitivity, >84% specificity, and > 82% accuracy for detection of the S1‐RBD antigen.ConclusionThe new S1‐RBD antigen test is a rapid (15 min), sensitive, and specific assay that requires minimal sample preparation. Critically, the assay correlated closely with PCR‐based methodology in nasopharyngeal swab samples, showing that the detected S1‐RBD antigen levels correlate with SARS‐CoV‐2 virus load. Therefore, the new TRF lateral flow test for S1‐RBD has potential application in point‐of‐care settings.  相似文献   
103.
104.
Surface treatment is known as a very efficient measure by which to modulate the surface properties of biomaterials in terms of grain structure, topography, roughness and chemistry to determine the osseointegration of implants. In this work, a two-step method of surface modification was employed to impart high osteogenic activity and biomineralization capacity on a Ti–25Nb–3Mo–2Sn–3Zr alloy (a type of β-titanium named TLM). The preliminary surface mechanical attrition treatment (SMAT) refined the average grain size from 170 ± 19 μm to 74 ± 8 nm in the TLM surface layer and promoted the surface to be much rougher and more hydrophilic. The subsequent Ca-ion implantation did not change the surface roughness and topography obviously, but enhanced the surface wettability of the SMAT-treated TLM alloy. The in vitro evaluations of the adhesion, proliferation, osteogenic genes (RUNX2, ALP, BMP-2, OPN, OCN and COL-I) and protein (ALP, OPN, OCN and COL-I) expressions, as well as extracellular matrix (ECM) mineralization of mesenchymal stem cells (MSCs) revealed that the initial SMAT-treated sample significantly enhanced the adhesion and osteogenic functions of MSCs compared to an untreated TLM sample, and the subsequent introduction of Ca ions onto the SMAT-derived nanograined sample further promotes the MSC adhesion, proliferation, osteo-differentiation and ECM mineralization due to the adsorption of more proteins such as laminin (Ln), fibronectin (Fn) and vitronectin (Vn) on the surface, as well as the increase in extracellular Ca concentrations. In addition, the biomineralization capacity of the samples was also evaluated by soaking them in simulated bodily fluid (SBF) at 37 °C for 28 days, and the results showed that the Ca-ion implanted sample significantly boosted the deposition of Ca and P containing minerals on its surface, which was associated with the generation of more Ti–OH groups on the surface after ion implantation. The combination of the SMAT technique and Ca-ion implantation thus endowed the TLM alloy with outstanding osteogenic and biomineralization properties, providing a potential means for its future use in the orthopedic field.

Combination of the SMAT technique and Ca-ion implantation produced a β-titanium alloy with a bioactive surface layer, which was proved to effectively promote the osteogenic activity of MSCs and Ca–P mineral deposition in vitro.  相似文献   
105.
目的 建立虚拟组织切片的体视学模型,并以软件系统作为实现手段,模拟虚拟切片过程,为体视学的理论提供一个客观实证工具.方法 以数学手段描述组织切片可能出现的二维形态特征,模拟切片过程,将所得到的数据进行数值分析,与经验公式进行了拟合比较.结果 基于此算法可实现虚拟随机模拟切片,经拟合优度检验数据分布的均匀性检验通过率达94.5%以上.独立性检验通过率达92%以上.且均符合正态性要求.经线性和曲线拟合能够得到与经验公式相一致的体视学参数相关关系.结论 本文所述算法具有可行性,可以反映数值模拟结果的正确性.  相似文献   
106.
107.
108.
Therapeutic nanoparticles are designed to enhance efficacy, real-time monitoring, targeting accuracy, biocompatibility, biodegradability, safety, and the synergy of diagnosis and treatment of diseases by leveraging the unique physicochemical and biological properties of well-developed bio-nanomaterials. Recently, bio-inspired metal nanoclusters (NCs) consisting of several to roughly dozens of atoms (<2 nm) have attracted increasing research interest, owing to their ultrafine size, tunable fluorescent capability, good biocompatibility, variable metallic composition, and extensive surface bio-functionalization. Hybrid core–shell nanostructures that effectively incorporate unique fluorescent inorganic moieties with various biomolecules, such as proteins (enzymes, antigens, and antibodies), DNA, and specific cells, create fluorescently visualized molecular nanoparticle. The resultant nanoparticles possess combinatorial properties and synergistic efficacy, such as simplicity, active bio-responsiveness, improved applicability, and low cost, for combination therapy, such as accurate targeting, bioimaging, and enhanced therapeutic and biocatalytic effects. In contrast to larger nanoparticles, bio-inspired metal NCs allow rapid renal clearance and better pharmacokinetics in biological systems. Notably, advances in nanoscience, interfacial chemistry, and biotechnologies have further spurred researchers to explore bio-inspired metal NCs for therapeutic purposes. The current review presents a comprehensive and timely overview of various metal NCs for various therapeutic applications, with a special emphasis on the design rationale behind the use of biomolecules/cells as the main scaffolds. In the different hybrid platform, we summarize the current challenges and emerging perspectives, which are expected to offer in-depth insight into the rational design of bio-inspired metal NCs for personalized treatment and clinical translation.Key words: Metal nanoclusters, Biomolecule, Nanoparticles, Hybrid system, Synergistic properties, Fluorescence, Bioprobe, Therapy  相似文献   
109.
张菁菁  陈浩 《安徽医药》2013,34(7):1023-1025
目的探讨早期护理干预在长春瑞滨治疗非小细胞肺癌所致静脉炎防治中的应用效果。方法将近年收治的采用长春瑞滨治疗的非小细胞肺癌患者,分为试验组和对照组,每组各40例,对照组采用常规护理措施,试验组采用早期护理干预措施,比较两组患者静脉炎的发生率及其程度。结果试验组静脉炎的发生率为7.5%,对照组为32.5%。与对照组相比较,试验组静脉炎的发生率降低,严重程度减轻。结论对采用长春瑞滨治疗的非小细胞肺癌患者进行有效的早期护理干预有助于降低静脉炎的发生率,促进患者的康复。  相似文献   
110.
目的:探索黄芩道地药材的历史分布区域,发展过程及道地产区变迁的原因.方法:考证历代地方志和现在文献研究.结果:气候变迁没有对黄芩的生长和分布起主导因素,而各省份的年平均气温、年降水量和年太阳辐射量对其生长和分布起主导作用.结论:河北省的气候最适合黄芩生长,可认为是最优越的产区,与传统经验相一致.黄芩的历代分布区域从长江以北的省区由南向北迁移.  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