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   6985篇
  免费   516篇
  国内免费   223篇
耳鼻咽喉   32篇
儿科学   57篇
妇产科学   129篇
基础医学   1489篇
口腔科学   209篇
临床医学   575篇
内科学   904篇
皮肤病学   141篇
神经病学   281篇
特种医学   116篇
外国民族医学   5篇
外科学   541篇
综合类   871篇
预防医学   500篇
眼科学   131篇
药学   1035篇
中国医学   204篇
肿瘤学   504篇
  2024年   9篇
  2023年   69篇
  2022年   100篇
  2021年   211篇
  2020年   183篇
  2019年   169篇
  2018年   173篇
  2017年   174篇
  2016年   206篇
  2015年   206篇
  2014年   408篇
  2013年   460篇
  2012年   494篇
  2011年   525篇
  2010年   435篇
  2009年   384篇
  2008年   364篇
  2007年   403篇
  2006年   306篇
  2005年   327篇
  2004年   253篇
  2003年   221篇
  2002年   195篇
  2001年   134篇
  2000年   132篇
  1999年   125篇
  1998年   100篇
  1997年   129篇
  1996年   101篇
  1995年   70篇
  1994年   71篇
  1993年   51篇
  1992年   59篇
  1991年   55篇
  1990年   32篇
  1989年   46篇
  1988年   28篇
  1987年   33篇
  1986年   22篇
  1985年   47篇
  1984年   41篇
  1983年   31篇
  1982年   39篇
  1981年   25篇
  1980年   21篇
  1979年   10篇
  1978年   17篇
  1977年   7篇
  1976年   8篇
  1975年   6篇
排序方式: 共有7724条查询结果,搜索用时 15 毫秒
991.
目的建立沙门氏菌实时荧光定量PCR的快速检测方法 ,探讨该方法的可行性和应用价值。方法根据沙门氏菌fimY基因序列设计引物和探针,采用基因重组技术构建用于沙门氏菌检测的定量标准品,建立实时荧光定量PCR检测沙门氏菌的方法。结果成功构建了沙门氏菌重组质粒标准品和沙门氏菌实时荧光定量PCR方法 ;通过特异性、敏感性、稳定性和重复性验证,结果表明具有较好的特异性、敏感性、稳定性和重复性;对模拟标本与分离培养对比,二者符合率为100%。结论沙门氏菌实时荧光定量PCR检测方法的建立,为食源性沙门氏菌污染的快速检测提供依据,可应用于食品卫生监管、商品检验检疫以及临床诊断等。  相似文献   
992.
目的:制备用于铜绿假单胞菌PAO1 quiP基因(PA1032)实时荧光定量PCR检测的质粒标准品pMD18-quiP。方法:通过PCR扩增出目的片断,纯化后连接至pMD18-T载体,转化宿主菌E.coli DH5α,获得阳性克隆,通过PCR扩增、双酶切鉴定和测序分析,确认重组质粒完整正确,大量抽提重组质粒,测定其拷贝浓度,10倍稀释成梯度标准品,并进行荧光定量PCR检测分析。结果:quiP基因目的片段成功重组至pMD18-T载体上,获得的重组质粒保持了目的片段的特异性和序列完整性。梯度浓度标准质粒的荧光定量PCR结果显示,循环阈值(Ct)与起始模板量的对数值之间有着良好的线性关系。结论:成功构建了quiP基因实时荧光定量PCR质粒标准品。  相似文献   
993.
994.
995.
996.
Inflammatory bowel disease is a chronic inflammatory disorder of the gastrointestinal tract associated with alterations and dysfunction of the intestinal microvasculature. The goal of this work was to develop a preclinical protocol for quantitative functional characterization of the colonic microvasculature in a murine colitis model. Experimental colitis was induced in mice by addition of dextran sodium sulfate to the drinking water. Histopathologic analysis revealed severe multifocal colitis. Dynamics of intravenously injected macromolecular dextran‐FITC and biotin‐BSA‐GdDTPA in the colonic microvasculature were imaged using fluorescent confocal endomicroscopy and MRI (9.4 T), respectively. Both MRI and fluorescent confocal endomicroscopy revealed a substantial increase in the permeability of the colonic microvasculature associated with colitis, resulting in extravascular accumulation of the macromolecular contrast agent in the lumen of the colon. MRI data were validated by immunohistochemical staining of the contrast agent and leakage of fluorescently labeled BSA‐FAM coinjected with the MRI contrast agent. Leakage of plasma proteins and deposition of a provisional matrix can support inflammation and stimulate remodeling of the colonic vasculature. Thus, the plasma protein leakage from the colonic microvasculature at the focal inflammatory patches could be quantified by MRI, providing a biomarker for assessment of disease progression. Magn Reson Med, 2011. © 2011 Wiley‐Liss, Inc.  相似文献   
997.
Understanding the nature of the caries lesion, disease activity, and the patient's caries risk are all used in determining the nature of dental care to be delivered. An examination should include a health and social history and clinical examination using appropriate technologies. This allows proper assessment and suggests a logical management intervention. Minimally invasive dentistry is a concept based on an assessment of a patient's caries risk and the application of the current therapies to prevent, control, and treat the disease. The history of the dental examination and the variety of current technologies are discussed.  相似文献   
998.
目的:探讨5-氨基乙酰丙酸(5-ALA)荧光膀胱镜的应用对非肌层浸润性膀胱癌术后早期复发率的影响。方法:将90例非肌层浸润性膀胱癌患者随机分为两组,每组45例,分别在白光膀胱镜和5-ALA荧光膀胱镜下行TURBt,术后6周所有患者均行5-ALA荧光膀胱镜检查以观察肿瘤复发情况,并对复发肿瘤行二次TURBt。结果:行二次TURBt后,90例患者中,25例(27.7%)发现有肿瘤发生,其中自光膀胱镜组18例(40%),荧光膀胱镜组7例(15.5%),两组间比较差异有统计学意义(P=0.05)。结论:5=ALA荧光膀胱镜对膀胱肿瘤的诊断和治疗具有较高价值,可以显著降低非肌层浸润性膀胱癌术后早期复发率。  相似文献   
999.
目的:研究5-氨基乙酰丙酸(5-ALA)诱导荧光光动力学对膀胱肿瘤的早期诊断价值。方法:对血尿患者行5-ALA诱导荧光膀胱镜检查及活组织检查,以5-ALA膀胱灌注,2h后采用D-light光源系统进行膀胱镜检,对荧光阳性区域及白光下肉眼可见异常但荧光阴性区域进行活检,活检后行经尿道膀胱肿瘤电切术。结果:31例患者中有4例荧光阴性且普通光肉眼观阴性者未活检。余27例患者共取活检96处,其中荧光阳性区域取活检89处(包括普通光肉眼观阴性区域35处),切缘取活检7处。病理检查结果显示:尿路上皮癌65处,阳性率为73.03%(65/89),非肿瘤性病变24例,假阳性率为27%(24/89),切缘活检7处为阴性。荧光下阳性而白光下阴性的肿瘤位点11处,切缘活检7处均为阴性。结论:5-ALA诱导荧光光动力学诊断对膀胱肿瘤有较高价值,能发现早期肿瘤,同时进行电切将更彻底。  相似文献   
1000.
What’s known on the subject? and What does the study add? So far we know that ERG rearrangements and PTEN deletions interact to induce prostate cancer in transgenic mice. The study confirms that an association also exists between the two genetic aberrations in human prostate cancer, as there is increased incidence of PTEN deletions in cases with ERG rearrangements.

OBJECTIVE

To investigate the interaction between, and significance of, ERG gene rearrangements and PTEN genomic deletions in relation to the development and progression of prostate cancer (PCA).

PATIENTS AND METHODS

We interrogated an initial cohort of 220 men with localized PCA using fluorescence in situ hybridization for ERG rearrangements and PTEN genomic deletions.

RESULTS

The incidences of ERG rearrangements and PTEN deletions in PCA were significantly higher than in high‐grade prostatic intra‐epithelial neoplasia (HGPIN) and benign prostate tissue (P < 0.001). ERG rearrangements and PTEN deletions were detected in 41.9 and 42.6% of patients’ tumours, respectively. ERG rearrangements were never detected in benign prostate tissue, while PTEN aberrations were present at a basal level of 4.6%. PTEN hemizygous deletions showed higher frequency than homozygous deletions within each diagnostic category from benign prostate tissue to HGPIN and PCA (P ≤ 0.001). Furthermore, in 29 patients where all three tissues were available, PTEN genomic aberrations in PCA were significantly different from those in benign tissue (P = 0.005) and HGPIN (P = 0.02), reflecting the accumulation of genomic aberrations in the early stages of disease progression. Within this cohort, 71.4% of homozygous and 44.2% of hemizygous PTEN deletions occurred simultaneously with ERG rearrangements (P ≈ 0). Stratified according to Gleason score (GS), hemizygous PTEN deletions across various GS groups were observed at a higher frequency than homozygous deletions. However, PTEN homozygous deletions showed positive trends with higher GS, increasing in poorly differentiated PCA (GS 8–10) in comparison to moderately and well differentiated tumours (GS 6 and 7).

CONCLUSION

We show significant association between ERG gene rearrangements and PTEN genomic aberrations in subset of PCA. Our analysis also provides further support for the observation that homozygous PTEN deletions can occur within the subset of HGPIN lesions, and shows accumulating genetic aberrations with disease progression, evidenced by higher detection in PCA than in HGPIN and more PTEN homozygous deletions in GS 8–10 than in 6–7.  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