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   3591篇
  免费   235篇
  国内免费   105篇
  2024年   6篇
  2023年   42篇
  2022年   34篇
  2021年   93篇
  2020年   97篇
  2019年   98篇
  2018年   120篇
  2017年   69篇
  2016年   93篇
  2015年   100篇
  2014年   187篇
  2013年   382篇
  2012年   122篇
  2011年   172篇
  2010年   132篇
  2009年   168篇
  2008年   175篇
  2007年   201篇
  2006年   174篇
  2005年   150篇
  2004年   156篇
  2003年   148篇
  2002年   115篇
  2001年   103篇
  2000年   102篇
  1999年   103篇
  1998年   87篇
  1997年   60篇
  1996年   61篇
  1995年   66篇
  1994年   56篇
  1993年   37篇
  1992年   22篇
  1991年   19篇
  1990年   18篇
  1989年   17篇
  1988年   18篇
  1987年   13篇
  1986年   13篇
  1985年   23篇
  1984年   18篇
  1983年   7篇
  1982年   17篇
  1981年   14篇
  1980年   4篇
  1979年   9篇
  1978年   3篇
  1977年   2篇
  1976年   2篇
  1973年   1篇
排序方式: 共有3931条查询结果,搜索用时 656 毫秒
81.
We have developed a model for evaluating the integral intercellular interactions in the “endotheliocyte‐neutrophil” system and have shown the high variability of adhesion contacts in different donors associated with different expression profiles of neutrophils. Two methods (forсe spectroscopy‐spectroscopy and scanning ion‐conductance microscopy) showed a decrease in the rigidity of the membrane‐cytoskeletal complex of neutrophils under the influence of Staphylococcus aureus 2879 M. Adding this strain to the “endotheliocyte‐neutrophil” system caused a statistically significant decrease in the adhesion force and adhesion work, which indicates a change in the expression profile and physicochemical properties of membranes of both types of interacting cells (neutrophils and endotheliocytes).  相似文献   
82.
作为一种无支架的组织工程技术,组织工程细胞片不仅可以避免支架材料带来的不利影响,而且可通过组装进一步形成更为复杂的三维功能化组织,因而在生物医学领域备受关注。细胞片的构建主要是基于敏感性材料所构建的培养基底,通过改变温度、酶、光、离子、氧化还原pH、糖等刺激因素,调节基底对细胞的粘附行为使细胞发生自然脱附,从而获取细胞片。近年来,随着研究的深入进行,特别是各种新型的敏感性培养基底的不断发展,各种简单高效的细胞片构建技术不断涌现,得到的各种具有优良性能的细胞片极大地扩展了其应用的广度和深度。文中对组织工程细胞片的各种构建方法进行了阐述,对其存在的问题及发展前景进行了分析和展望。  相似文献   
83.
ObjectivesSalivary gland regeneration is closely related to the parasympathetic nerve; however, the mechanism behind this relationship is still unclear. The aim of this study was to evaluate the relationship between the parasympathetic nerve and morphological differences during salivary gland regeneration.Materials and MethodsWe used a duct ligation/deligation‐induced submandibular gland regeneration model of Sprague‐Dawley (SD) rats. The regenerated submandibular gland with or without chorda lingual (CL) innervation was detected by haematoxylin–eosin staining, real‐time PCR (RT‐PCR), immunohistochemistry and Western blotting. We counted the number of Ki67‐positive cells to reveal the proliferation process that occurs during gland regeneration. Finally, we examined the expression of the following markers: aquaporin 5, cytokeratin 7, neural cell adhesion molecule (NCAM) and polysialyltransferases.ResultsIntact parasympathetic innervation promoted submandibular gland regeneration. The process of gland regeneration was significantly repressed by cutting off the CL nerve. During gland regeneration, Ki67‐positive cells were mainly found in the ductal structures. Moreover, the expression of NCAM and polysialyltransferases‐1 (PST) expression in the innervation group was significantly increased during early regeneration and decreased in the late stages. In the denervated submandibular glands, the expression of NCAM decreased during regeneration.ConclusionsOur findings revealed that the regeneration of submandibular glands with intact parasympathetic innervation was associated with duct cell proliferation and the increased expression of PST and NCAM.  相似文献   
84.
摘要 目的:探讨慢性阻塞性肺疾病(COPD)稳定期患者血清血管黏附蛋白-1(VAP-1)、巨噬细胞刺激蛋白(MSP)、基质细胞衍生因子-1(SDF-1)水平与肺功能、炎性因子及生活质量的关系。方法:选取我院2018年9月~2020年9月收治的COPD稳定期患者116例作为COPD组,选取同期于我院体检的健康志愿者100例作为对照组。比较两组血清VAP-1、MSP、SDF-1水平以及肺功能指标[第1秒用力呼气容积(FEV1)、用力肺活量(FVC)、FEV1/FVC、最大呼气流速(PEF)]、炎症因子[白介素-6(IL-6)、白介素-17(IL-17)、白介素-22(IL-22)、肿瘤坏死因子-α(TNF-α)]水平。根据COPD稳定期患者的严重程度,分成轻度组(n=53)、中度组(n=34)、重度组(n=29),比较三组上述各指标水平。采用COPD评估测试表(CAT)评估三组生活质量并进行比较,经Pearson线性相关分析血清VAP-1、MSP、SDF-1水平与肺功能、炎性因子及CAT评分的相关性。结果:COPD组血清VAP-1、MSP、SDF-1、IL-6、IL-17、IL-22及TNF-α水平均高于对照组,而FEV1、FVC、FEV1/FVC以及PEF低于对照组(P<0.05)。轻度组血清VAP-1、MSP、SDF-1、IL-6、IL-17、IL-22、TNF-α水平及CAT评分较中度、重度组明显降低,且中度组低于重度组,而轻度组FEV1、FVC、FEV1/FVC、PEF较中度、重度组增高,且中度组高于重度组(P<0.05)。Pearson线性相关分析提示,血清VAP-1、MSP、SDF-1水平与FEV1、FVC、FEV1/FVC、PEF呈负相关,三者与血清IL-6、IL-17、IL-22、TNF-α水平及CAT评分呈正相关(P<0.05)。结论:COPD稳定期患者的血清VAP-1、MSP、SDF-1水平明显上调,且三者与患者的肺功能、炎症因子及生活质量密切相关,临床有望通过测定血清VAP-1、MSP、SDF-1水平,评估COPD稳定期患者病情进展情况。  相似文献   
85.
摘要 目的:探究胸腔积液中肺腺癌细胞表皮生长因子受体(epidermalgrowthfactorreceptor,EGFR)突变状态与DNA含量的相关性,以期探究EGFR突变状态是否同肿瘤的恶性程度存在一定关联。方法:选择2015年1月至2020年1月于我院接受EGFR基因检测以及基因定量分析的591例肺腺癌患者为研究对象,按照其是否出现EGFR基因突变将其分为突变组(335例)与非突变组(256例),两组患者的胸腔积液均使用激光图像细胞仪开展DNA含量以及非整倍体峰检测,并开展组间差异性比较。结果:(1)将591例患者按照年龄、性别及是否吸烟等临床特征进行分组对比显示,性别(P=0.034)与吸烟(P=0.007)同肺腺癌患者胸腔积液细胞出现EGFR突变具有一定关联,而年龄因素与是否出现突变无明显相关性(P>0.05);(2)突变组患者的最大DNA指数(DI)、大于5C细胞的平均DI以及大于9C细胞的平均DI均明显高于非突变组,组间差异明显(P<0.05);(3)开展DNA非整倍体细胞峰比较显示突变组在单峰、双峰占比中明显高于非突变组,而无峰占比明显低于非突变组(P<0.05),多峰占比方面两组差异不大(P>0.05)。结论:经研究显示,同未出现EGFR突变的肺腺癌患者相比较,发生EGFR突变的肺腺癌患者明显DI值更高,非整倍体细胞以及非整倍体峰值也呈现异常升高态,这提示EGFR发生突变的肺腺癌患者恶变洗吧的侵袭性更强。  相似文献   
86.
摘要 目的:对比宫腔镜下冷刀分离术与电切术治疗宫腔粘连(IUA)的疗效及对宫腔形态恢复和血清白细胞介素的影响。方法:回顾性分析2019年4月~2021年2月期间来我院接受治疗的83例IUA患者的临床资料。根据手术方式的不同将患者分为A组(宫腔镜下电切术,40例)和B组(宫腔镜下冷刀分离术,43例),对比两组手术时间及住院时间、宫腔形态恢复情况和血清白细胞介素变化,观察两组术后并发症发生率、月经改善率和宫腔再粘连发生率。结果:B组手术时间、住院时间短于A组(P<0.05)。B组总有效率、内膜创面上皮化愈合满意率均高于A组(P<0.05)。两组血清白细胞介素-6(IL-6)、白细胞介素-8(IL-8)水平升高,但B组低于A组(P<0.05)。两组血清白细胞介素-4(IL-4)、白细胞介素-10(IL-10)降低,但B组高于A组(P<0.05)。两组术后并发症发生率组间对比无统计学差异(P>0.05)。B组月经改善率高于A组,宫腔再粘连发生率低于A组(P<0.05)。结论:与宫腔镜下电切术治疗IUA相比,宫腔镜下冷刀分离术治疗IUA手术时间、住院时间更短,宫腔形态恢复和月经改善情况更好,机体炎性反应更轻微,同时宫腔再粘连发生率更低,疗效更优。  相似文献   
87.
Hepatocellular carcinoma (HCC) is one of the most common metastatic tumours. Tumour growth and metastasis depend on the induction of cell proliferation and migration by various mediators. Here, we report that the A Disintegrin and Metalloproteinase (ADAM) 8 is highly expressed in murine HCC tissues as well as in murine and human hepatoma cell lines Hepa1-6 and HepG2, respectively. To establish a dose-dependent role of different ADAM8 expression levels for HCC progression, ADAM8 expression was either reduced via shRNA- or siRNA-mediated knockdown or increased by using a retroviral overexpression vector. These two complementary approaches revealed that ADAM8 expression levels correlated positively with proliferation, clonogenicity, migration and matrix invasion and negatively with apoptosis of hepatoma cells. Furthermore, the analysis of pro-migratory and proliferative signalling pathways revealed that ADAM8 expression level was positively associated with expression of β1 integrin as well as with the activation of focal adhesion kinase (FAK), mitogen-activated protein kinase (MAPK), Src kinase and Rho A GTPase. Finally, up-regulation of promigatory signalling and cell migration was also seen with a proteolytically inactive ADAM8 mutant. These findings reveal that ADAM8 is critically up-regulated in hepatoma cells contributes to cell proliferation and survival and furthermore induces pro-migratory signalling pathways independently of its proteolytic activity. By this, ADAM8 can promote cell functions most relevant for HCC growth and metastasis.  相似文献   
88.
89.
Overexpression of breast cancer resistance protein (BCRP) plays a crucial role in the acquired multidrug resistance (MDR) in breast cancer. The elucidation of molecular events that confer BCRP-mediated MDR is of major therapeutic importance in breast cancer. Epithelial cell adhesion molecule (EpCAM) has been implicated in tumor progression and drug resistance in various types of cancers, including breast cancer. However, the role of EpCAM in BCRP-mediated MDR in breast cancer remains unknown. In the present study, we revealed that EpCAM expression was upregulated in BCRP-overexpressing breast cancer MCF-7/MX cells, and EpCAM knockdown using siRNA reduced BCRP expression and increased the sensitivity of MCF-7/MX cells to mitoxantrone (MX). The epithelial–mesenchymal transition (EMT) promoted BCRP-mediated MDR in breast cancer cells, and EpCAM knockdown partially suppressed EMT progression in MCF-7/MX cells. In addition, Wnt/β-catenin signaling was activated in MCF-7/MX cells, and the inhibition of this signaling attenuated EpCAM and BCRP expression and partially reversed EMT. Together, this study illustrates that EpCAM upregulation by Wnt/β-catenin signaling induces partial EMT to promote BCRP-mediated MDR resistance in breast cancer cells. EpCAM may be a potential therapeutic target for overcoming BCRP-mediated resistance in human breast cancer.  相似文献   
90.
IntroductionProstate and breast cancer are the most prevalent primary malignant human tumors globally. Prostatectomy and breast conservative surgery remain the most common definitive treatment option for the >500,000 men and women newly diagnosed with localized prostate and breast cancer each year only in the US. Morphological examination is the mainstay of diagnosis but margin under-sampling of the excised cancer tissue may lead to local recurrence. In despite of the progress of non-invasive optical imaging, there is still a clinical need for targeted optical imaging probes that could rapidly and globally visualize cancerous tissues.MethodsElevated expression of junctional adhesion molecule-A (JAM-A) on tumor cells and its multiple pro-tumorigenic activity make the JAM-A a candidate for molecular imaging. Near-infrared imaging probe, which employed anti-JAM-A monoclonal antibody (mAb) phthalocyanine dye IR700 conjugates (JAM-A mAb/IR700), was synthesized and used to identify and visualize heterotopic human prostate and breast tumor mouse xenografts in vivo.ResultsThe intravenously injected JAM-A mAb/IR700 conjugates enabled the non-invasive detection of prostate and breast cancerous tissue by fluorescence imaging. A single dose of JAM-A mAb/IR700 reduced number of mitotic cancer cells in vivo, indicating theranostic ability of this imaging agent. The JAM-A mAb/IR700 conjugates allowed us to image a specific receptor expression in prostate and breast tumors without post-image processing.ConclusionThis agent demonstrates promise as a method to image the extent of prostate and breast cancer in vivo and could assist with real-time visualization of extracapsular extension of cancerous tissue.  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