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   1304篇
  免费   122篇
  国内免费   59篇
  2024年   6篇
  2023年   41篇
  2022年   61篇
  2021年   83篇
  2020年   60篇
  2019年   83篇
  2018年   70篇
  2017年   66篇
  2016年   68篇
  2015年   65篇
  2014年   102篇
  2013年   121篇
  2012年   58篇
  2011年   80篇
  2010年   41篇
  2009年   43篇
  2008年   62篇
  2007年   54篇
  2006年   35篇
  2005年   37篇
  2004年   29篇
  2003年   27篇
  2002年   15篇
  2001年   18篇
  2000年   16篇
  1999年   10篇
  1998年   10篇
  1997年   7篇
  1996年   6篇
  1995年   12篇
  1994年   14篇
  1993年   10篇
  1992年   5篇
  1991年   2篇
  1990年   7篇
  1989年   6篇
  1988年   6篇
  1987年   2篇
  1986年   6篇
  1985年   8篇
  1984年   11篇
  1983年   1篇
  1982年   1篇
  1981年   2篇
  1979年   3篇
  1978年   5篇
  1977年   4篇
  1975年   4篇
  1974年   2篇
排序方式: 共有1485条查询结果,搜索用时 16 毫秒
991.
BackgroundOral cancer, a leading cancer-site in India, is often detected at advanced stages. We evaluated the time intervals from first symptom to help-seeking and diagnosis among oral cancer patients.MethodologyIn this cross-sectional study, we recruited 226 consecutive oral cancer patients (mean age ( ± SD) 51.9 years ( ± 10.9); 81.9% men; 70.3% advanced stage) registered for diagnosis and treatment, between 2019 and 2021 at a cancer care centre in South India. We used WHO framework and previously standardized tools to record time intervals (appraisal, help-seeking and diagnostic) and baseline characteristics. We utilized multivariable logistic regression models to test the associations between ‘prolonged (i.e., over 1 month) time intervals’) and patient-level factors to estimate odds ratios (ORs) with 95% confidence intervals (CIs).ResultsOver a half of patients presented with prolonged appraisal (60%) and help-seeking intervals (57%), and a third (34%) reported prolonged diagnostic interval. Patients with no formal education, no routine healthcare visits, no self-reported risk factors, and those who did not perceive initial symptoms to be serious were 2–4 times more likely to have prolonged appraisal and help-seeking than the rest. High travel costs and self-decision for visiting healthcare facility prolonged help-seeking. Diagnostic interval was prolonged only among women OR= 2.7 (95% CI: 1.2–6.1)) and in patients whose first doctor’s opinion was ‘nothing to worry’ OR (=7.3 (95% CI: 2.6–20.5)). ‘Correct knowledge of cancer’ shortened appraisal and help-seeking intervals and ‘incorrect knowledge and negative beliefs’ prolonged diagnostic interval.ConclusionOur findings highlight that interventions targeting sociocultural and economic determinants, symptom awareness, sensitizing persons at risk (especially women) and primary care providers might reduce overall time to diagnosis. Further, patients without any known risk factors for oral cancer might be at-risk for prolonged appraisal interval. These might help inform ‘pull’ strategies for cancer control in India and similar settings.  相似文献   
992.
The delivery of drugs to the brain is complicated by the multiple factors including low blood–brain barrier (BBB) passive permeability, active BBB efflux systems, and plasma protein binding. Thus, a detailed understanding of the transport of the new potent substances through the membranes is vitally important and their physico-chemical characteristics should be analyzed at first. This work presents an evaluation of drug likeness of eight 7-O-arylpiperazinylcoumarin derivatives with high affinity towards serotoninergic receptors 5-HT1A and 5-HT2A with particular analysis of the requirements for the CNS chemotherapeutics. The binding constants to human serum albumin (HSA) were determined at physiological pH using fluorescence spectroscopy, and then their mode of action was explained by analysis of theoretical HSA complexes. Dynamic simulation of systems allowed for reliable evaluation of the interaction strength. The analyzed coumarins were able to pass BBB, and they present good drug likeness properties. They showed high affinities to HSA (log KQ = 5.3–6.0 which corresponds to −8.12 to −7.15 kcalmol−1 of Gibbs free energy). The changes of the emission intensity upon binding to HSA were scrutinized showing the different mode of action for 4-phenylpiperazinylcoumarins. The values of computed Gibbs free energy and determined on the basis of experimentally obtained binding constants log KQ coincide suggesting a good quality of the theoretical model. Overall the 8-acetyl-7-O-arylpiperazinyl-4-methylcoumarin derivatives represent valuable lead compounds to be further tested in various preclinical assays as a possible chemotherapeutics against CNS diseases. Studied coumarins can be metabolized by cytochrome P450 to aldehydes and hydroxy derivatives. The existence of other binding sites inside HSA than Sudlow’s site 1 was postulated. The longer aliphatic linker between coumarin and piperazine moieties favored binding to HSA in other than Sudlow site 1 pocket.  相似文献   
993.
MicroRNAs (miRNAs) play crucial roles in various biological processes, including migration, proliferation, differentiation, cell cycling, and apoptosis. Epithelial-mesenchymal transition (EMT) has been shown to be related to the capability of migration and invasion in many tumor cells. In this study, we used wound-healing assay and transwell invasion to analysis the capability of migration and invasion in non–small-cell lung carcinoma (NSCLC), respectively. The expression of ubiquitin-specific protease-9-X-linked (USP9X) and miR-212 messenger RNA (mRNA) was determined by quantitative real-time polymerase chain reaction and Western blot analysis was used to determine the E-cadherin and vimentin expression. Our results showed that miR-212 mimic inhibited cell migration and invasion, while miR-212 inhibitor increased cell migration and invasion. There was no significant difference between WP1130 and miR-212 mimic combined with WP1130 groups. Moreover, WP1130 inhibited the capability of the migration and invasion of NSCLC cells. Western blot analysis displayed that miR-212 mimic upregulated E-cadherin expression and downregulated vimentin expression, while miR-212 inhibitor downregulated E-cadherin and upregulated vimentin expression. These data showed that miR-212 regulated NSCLC cell invasion and migration by regulating USP9X expression. Taken together, these findings indicated that miR-212 regulated NSCLC cells migration and invasion through targeting USP9X involved in EMT.  相似文献   
994.
The gut associated lymphoid tissue has effective mechanisms in place to maintain tolerance to food antigens. These can be exploited to induce antigen-specific tolerance for the prevention and treatment of autoimmune diseases and severe allergies and to prevent serious immune responses in protein replacement therapies for genetic diseases. An oral tolerance approach for the prevention of peanut allergy in infants proved highly efficacious and advances in treatment of peanut allergy have brought forth an oral immunotherapy drug that is currently awaiting FDA approval. Several other protein antigens made in plant cells are in clinical development. Plant cell-made proteins are protected in the stomach from acids and enzymes after their oral delivery because of bioencapsulation within plant cell wall, but are released to the immune system upon digestion by gut microbes. Utilization of fusion protein technologies facilitates their delivery to the immune system, oral tolerance induction at low antigen doses, resulting in efficient induction of FoxP3+ and latency-associated peptide (LAP)+ regulatory T cells that express immune suppressive cytokines such as IL-10. LAP and IL-10 expression represent potential biomarkers for plant-based oral tolerance. Efficacy studies in hemophilia dogs support clinical development of oral delivery of bioencapsulated antigens to prevent anti-drug antibody formation. Production of clinical grade materials in cGMP facilities, stability of antigens in lyophilized plant cells for several years when stored at ambient temperature, efficacy of oral delivery of human doses in large animal models and lack of toxicity augur well for clinical advancement of this novel drug delivery concept.  相似文献   
995.
The clinical applications of therapeutic enzymes are often limited due to their immunogenicity. B-cell epitope removal is an effective approach to solve this obstacle. The identification of hot spot epitopic residues is a critical step in the removal of protein B-cell epitope. Hereof, computational approaches are a suitable alternative to costly and labor-intensive experimental approaches. Arginine deiminase, a Mycoplasma arginine-catabolizing enzyme, is in the clinical trial for treating arginine auxotrophic cancers, especially hepatocellular carcinomas and melanomas through depleting plasma arginine and causing cell starvation. In this study, arginine deiminase from Mycoplasma hominis (MhADI) was computationally analyzed for recognizing and locating its immune-reactive regions. The 3D structure of the bioactive form of MhADI was modeled. The B-cell epitope mapping of protein was performed using various servers with different algorithms. Six segments: 31–40, 48–55, 131–140, 196–206, 294–314, and 331–344 were predicted to be the consensus immunogenic regions. The modification of epitopic hot spot residue was performed to reduce immune-reactiveness. The hot spot residue was selected considering a high B-cell epitope score, convexity index, surface accessibility, flexibility, and hydrophilicity. The structure stability of native and mutant proteins was evaluated through molecular dynamics simulation. The E304L mutein was suggested as a lower antigenic and stable enzyme derivative.  相似文献   
996.
997.
Introduction: Cancer represents one of the major causes of human deaths. Identification of proteins as biomarkers for early detection of cancer and therapeutic targets for cancer treatment are important issues in precision medicine. Secretome of cancer cells represents the collection of proteins secreted or shed from cancer cells. Proteomic profiling of the cancer cell secretome has been proven to be a convenient and efficient way to discover cancer biomarker and/or therapeutic targets.

Areas covered: There have been numerous reviews describing the history and application of secretome analysis in cancer biomarker/therapeutic target research. The present review focuses on the technological advancement for profiling low-molecular-mass proteins in secretome, the latest information regarding the new candidate biomarkers and molecular mechanisms discovered on the basis of cancer cell secretome analysis, as well as the previously discovered candidate biomarkers that enter into clinical trials.

Expert commentary: Current technologies for protein sample preparation/separation and MS-based protein identification have allowed in-depth analysis of cancer cell secretome. Future efforts should focus on the comprehensiveness of cancer cell secretome, meta-analysis of different secretome datasets and integrated analysis via combining other omics datasets, as well as the incorporation of MS-based biomarker verification pipeline into both preclinical studies and clinical trials.  相似文献   

998.
目的:对颏下岛状皮瓣修复口腔颌面部肿瘤术后缺损患者进行观察与探讨,为临床应用颏下岛状皮瓣修复治疗存在口腔颌面部肿瘤术后缺损情况的患者提供依据。方法:对2013年6月到2015年6月期间在医院接受颏下岛状皮瓣修复治疗的60例口腔颌面部肿瘤术后缺损患者进行临床回顾性研究,按照是否存在颈淋巴结转移分为两组进行研究比较。结果:研究组口腔颌面部肿瘤术后缺损患者的颏下岛状皮瓣存活率,术后复发率,术后6个月、1年、2年的生存率,术后并发症总发生率,总满意度与对照组口腔颌面部肿瘤术后缺损患者相比,组间差异不明显(P0.05),不具有统计学意义。结论:使用颏下岛状皮瓣修复治疗口腔颌面部肿瘤术后缺损患者的效果较好,大多数患者对于临床修复治疗效果比较满意。而且,对存在颈淋巴结转移的患者实施颈部淋巴结的清扫术及术后放疗对于临床疗效的影响不大,基本不影响皮瓣的存活,具有重要的临床应用价值。  相似文献   
999.
Ferroptosis is a newly recognized mechanism of regulated cell death. It was reported to be highly associated with immune therapy and chemotherapy. However, its mechanism of regulation in the tumor microenvironment (TME) and influence on oral squamous cell carcinoma (OSCC) therapy are unknown. We identified a ferroptosis-specific gene-expression signature, an FPscore, developed by a principal component analysis (PCA) algorithm to evaluate the ferroptosis regulation patterns of individual tumor. Multi-omics analysis of ferroptosis regulation patterns was conducted. Three distinct ferroptosis regulation subtypes, which linked to outcomes and the clinical relevance of each patient, were established. A high FPscore of patients with OSCC was associated with a favorable prognosis, a ferroptosis-related immune-activation phenotype, potential sensitivities to the chemotherapy and immunotherapy. Importantly, a high FPscore correlated with a low gene copy number burden and high immune checkpoint expressions. We validated the prognostic value of the FPscore using independent immunotherapy and pan-cancer cohorts. Comprehensive evaluation of individual tumors with distinct ferroptosis regulation patterns provides new mechanistic insights, which may be clinically relevant for the application of combination therapies in OSCC.  相似文献   
1000.
贻贝棘尾虫口器的结构   总被引:1,自引:0,他引:1  
利用半薄连续切片和超薄切片对贻尾虫口器的显微及亚显微结构进行了观察,澄清了口侧膜和口内膜的立体位置,它们均为纤毛膜,口侧膜发自内唇的边缘,由两排纤毛构成,口内膜发自口围右壁,紧贴口围顶壁向左伸展,由单排纤毛组成,在口内膜的腹侧发现一非纤毛厚膜,暂定名为吞噬辅助膜,它由两层质膜夹一纵行微管束层构成,至口围后部口围带内收之处,此膜再向腹侧延伸出第二个膜,共同构成括号状,至胞口处此膜与口内和口侧膜互相包卷而成一包卷体,共同进入胸咽,经分析认为此膜及其与两纤毛膜形成的包者体,对棘尾虫摄取的大固体食物起重要作用。  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