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   26591篇
  免费   3136篇
  国内免费   1999篇
耳鼻咽喉   172篇
儿科学   309篇
妇产科学   243篇
基础医学   2963篇
口腔科学   627篇
临床医学   3766篇
内科学   3557篇
皮肤病学   297篇
神经病学   1304篇
特种医学   933篇
外国民族医学   23篇
外科学   2589篇
综合类   4797篇
现状与发展   5篇
一般理论   3篇
预防医学   2181篇
眼科学   660篇
药学   2924篇
  47篇
中国医学   2183篇
肿瘤学   2143篇
  2024年   160篇
  2023年   655篇
  2022年   1541篇
  2021年   1811篇
  2020年   1401篇
  2019年   1135篇
  2018年   1114篇
  2017年   1087篇
  2016年   1014篇
  2015年   1462篇
  2014年   1658篇
  2013年   1578篇
  2012年   1985篇
  2011年   2209篇
  2010年   1463篇
  2009年   1261篇
  2008年   1398篇
  2007年   1287篇
  2006年   1207篇
  2005年   1140篇
  2004年   711篇
  2003年   686篇
  2002年   569篇
  2001年   410篇
  2000年   422篇
  1999年   446篇
  1998年   261篇
  1997年   273篇
  1996年   170篇
  1995年   177篇
  1994年   151篇
  1993年   91篇
  1992年   107篇
  1991年   87篇
  1990年   100篇
  1989年   73篇
  1988年   91篇
  1987年   54篇
  1986年   48篇
  1985年   32篇
  1984年   13篇
  1983年   15篇
  1981年   13篇
  1979年   19篇
  1977年   10篇
  1975年   11篇
  1974年   10篇
  1973年   15篇
  1969年   14篇
  1966年   9篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
991.
The prevalence of nasopharyngeal cancer (NPC) is high in the southern area of China and some other districts in the world. The pathogenesis of NPC is unclear. It is reported that some microRNAs (miR) are involved in the progression of NPC. This study aims to investigate the role of miR-21 in the induction of immune tolerance of NPC. In this study, NPC tissue was collected from patients with NPC. Assessment of miR was performed with real time quantitative RT-PCR. Western blotting was used to assess proteins of interleukin 10 and nuclear factor I-A (NFI-A). Immune cells were analyzed by flow cytometry. The results showed that NPC cell line C666-1 and surgically removed NPC tissue expressed miR-21, which was upregulated by the presence of the Toll-like receptor 3 ligand, Poly I: C. Exposure to miR-21 increased the expression of NFI-A and interleukin (IL)-10 in naive B cells. High frequency of IL-10+ B cells was detected in the NPC tissue. The NPC- or miR-21-primed B cells suppressed cytotoxic CD8+ T cell activities. We conclude that NPC-derived miR-21 induces IL-10+ B cells; the latter is capable of suppressing CD8+ T-cell activities. miR-21 may be a potential target in the treatment of NPC.  相似文献   
992.
目的 研究肿瘤标志物在良恶性胸腹水的临床鉴别价值.方法 169例恶性胸腹水患者设为恶性腹水组,146例良性胸腹水设为良性组,比较两组胸腹水癌胚抗原(CEA)、甲胎蛋白(AFP)、糖类抗原(CA) 125、CA19-9水平,并对各肿瘤标志物对良恶性胸腹水的诊断进行方法学评价.结果 恶性组的CEA为(139.7-±56.4) ng/mL、AFP为(189.2±45.2) ng/mL、CA125为(314.7±86.2) U/mL、CA19-9为(158.5±24.2) U/mL,浓度均高于良性组,差异有统计学意义(均P<0.05);ROC曲线分析CEA、AFP、CA125以及CA19-9曲线下面积分别为0.811、0.547、0.715和0.769,其对应的诊断切点分别为5.6 ng/mL、63.7 ng/mL、38.9 U/mL和30.4 U/mL;AFP因ROC曲线下面积过低不适于恶性胸腹水的诊断.三种肿瘤标志物单独检测方法学评价的各项指标均以CEA最好,灵敏度为75.7%,特异度为88.6%,联合检测以CEA、CA125以及CA19-9的联合检测效果较好,灵敏度为80.5%,特异度为94.0%.结论 肿瘤标志物联合检测对胸腹水的性质鉴别方面有重要的临床应用价值.  相似文献   
993.
OBJECTIVE:To determine the range of motion and stability of the human cadaveric cervical spine after the implantation of a novel artificial disc and vertebra system by comparing an intact group and a fusion group.METHODS:Biomechanical tests were conducted on 18 human cadaveric cervical specimens. The range of motion and the stability index range of motion were measured to study the function and stability of the artificial disc and vertebra system of the intact group compared with the fusion group.RESULTS:In all cases, the artificial disc and vertebra system maintained intervertebral motion and reestablished vertebral height at the operative level. After its implantation, there was no significant difference in the range of motion (ROM) of C3–7 in all directions in the non-fusion group compared with the intact group (p>0.05), but significant differences were detected in flexion, extension and axial rotation compared with the fusion group (p<0.05). The ROM of adjacent segments (C3−4, C6−7) of the non-fusion group decreased significantly in some directions compared with the fusion group (p<0.05). Significant differences in the C4-6 ROM in some directions were detected between the non-fusion group and the intact group. In the fusion group, the C4−6 ROM in all directions decreased significantly compared with the intact and non-fusion groups (p<0.01). The stability index ROM (SI-ROM) of some directions was negative in the non-fusion group, and a significant difference in SI-ROM was only found in the C4−6 segment of the non-fusion group compared with the fusion group.CONCLUSION:An artificial disc and vertebra system could restore vertebral height and preserve the dynamic function of the surgical area and could theoretically reduce the risk of adjacent segment degeneration compared with the anterior fusion procedure. However, our results should be considered with caution because of the low power of the study. The use of a larger sample should be considered in future studies.  相似文献   
994.
The present study was to examine the distribution of lymphatic vessels in the penis of normal adult males, which could provide an anatomical basis for improvement of incisions in penile lengthening surgery, and may also help to prevent postoperative refractory edema. Thirteen normal adult male volunteers were recruited for this study. Contrast agent was injected subcutaneously in the foreskin of the penis, and after two minutes magnetic resonance lymphangiography (MRL) was performed. The acquired magnetic resonance images were analyzed to determine the changes in the number and diameter of lymphatic vessels in different parts of the penis. Maximum intensity projections (MIP) and materializes interactive medical image control system (MIMICS) were applied to analyze the overall distribution of lymphatic vessels in the penis. Magnetic resonance imaging (MRI) showed that the lymphatic vessels were in conspicuous contrast with surrounding tissues and could be clearly identified. Penile lymphatic vessels were clearly visible in the root of the penis. At the junction of the penis and the abdominal wall, all lymphatic vessels were found to be concentrated in the dorsal part of the penis. MIP two‐dimensional reconstruction showed that the overall distribution of relatively large lymphatic vessels in the dorsal and ventral parts of the penis could be seen clearly on bilateral 45° position, but not inside the abdominal wall because some of lymphatic vessels were overlapped by other tissues in the abdomen. MIMICS three‐dimensional reconstruction was able to reveal the overall spatial distribution of lymphatic vessels in the penis from any angle. The reconstruction results showed that there were 1–2 main lymphatic vessels on the root of dorsal penis, which coursed along the cavernous to the first physiological curvature of the penis. Lymphatic vessels merged on both sides of the ventral penis. At the root of the penis, lymphatic vessels gradually coursed to the dorsal surface of the penis and folded at the abdominal wall to the outside, and finally merged into the inguinal lymph nodes. The changes in distribution, number and diameter of the lymphatic vessels in the penis were observed by MRI. MIP and MIMICS reconstructions directly revealed the anatomical features of penile lymphatic vessels such as spatial distribution, overall alignment, and the relations to adjacent structures, drainage and reflux. The study will provide the anatomical basis for penile surgery, penile lymphatic reflux disorders caused by trauma or lymphatic vessels obstruction, and lymph node metastasis in penile cancer. Anat Rec, 298:1465–1471, 2015. © 2014 Wiley Periodicals, Inc.  相似文献   
995.
996.
Laryngeal squamous cell carcinoma is a common malignant tumor of otolaryngeal region. At present, effective treatment of laryngeal squamous cell carcinoma still depends on surgery and radiotherapy. In recent years, application of CO2 laser resection in the treatment of stage T1 glottic carcinoma can remove the tumor completely and reduce the injury of laryngeal tissues. But recurrence still happened in some postoperative patients. Here, we selected 131 patients to compare the therapeutic effects of CO2 laser resection and traditional split laryngeal surgery on the early laryngeal cancer, examined the expression of p27 and PTEN by immunohistochemistry in early laryngeal squamous cell carcinoma tissues in correlation to clinical outcome. After two years follow-up 14/85 (16.5%) of CO2 laser treatment group presented with local recurrence (recurrent group), while that of split laryngeal surgery group was 6/46 (13.0%). There was no statistical significance in recurrence rate between the two groups (P > 0.05). 10 of all the 111 (9.0%) non-recurrent patients did not follow the doctor’s advice to quit smoking after the operation, while 12 in the 20 (60.0%) recurrent patients did not; the difference between the two groups was statistically significant (P < 0.01). The positive rates of p27 were 80.2% (105/131) and 43.5% (57/131), and that of PTEN were 83.2% (109/131) and 48.9% (64/131) in the cancer adjacent tissues (negative surgical margin tissues) and in laryngeal carcinoma tissues, respectively (P < 0.001). The expression rates of p27 and PTEN in laryngeal carcinoma tissues of the recurrent group were 20.0% (4/20), 10.0% (2/20) and that in non recurrent group were 47.7% (53/111) and 55.9% (62/111), respectively, with a significant difference (P < 0.001). In addition, the expression of p27 and PTEN in tumor resected marginal tissues of the recurrence group was 50.0% (10/20), 40.0% (8/20) and that in non recurrence group was 85.6% (95/111) and 91.0% (101/111), respectively; the difference was also statistically significant between both groups (P < 0.001). In conclusion, there is no statistically significant difference in tumor recurrence rate between CO2 laser surgery and traditional split laryngeal surgery. Postoperative recurrence is closely related to resume smoking. The recurrence rate of p27 and/or PTEN-negative patients was higher than that of the positive ones,that should be followed up closely after treatment.  相似文献   
997.
种植体周围炎是种植义齿常见的并发症,是导致种植义齿失败的主要原因。种植体表面去污会影响种植体周围炎手术治疗的疗效,是种植体周围骨缺损重建前的必要处理步骤。由于良好的杀菌和去污能力,激光疗法和光动力学疗法在处理污染种植体表面上拥有良好的应用前景。本文就不同种植体表面去污的方法及其联合手术疗法治疗种植体周围炎的效果作一归纳总结。  相似文献   
998.
本研究旨在探讨高校科技期刊如何在了解自身需求的基础上,去认识、利用、开发数字化平台,从而更有效的促进期刊内容快速的传播、推进期刊编辑部的办公流程、获取与分享期刊信息与资源,从而整体提高高校学术期刊的学术水平和出版质量。  相似文献   
999.
目的探讨不同的超声引导方式对经皮颈内静脉穿刺血透导管置管术成功率和并发症及操作时间的影响。方法总结分析了2011年5月-2013年4月兰州军区兰州总医院336例经临床评估需行血液净化治疗的肾脏病患者,在彩色多普勒超声实时引导下行经皮颈内静脉穿刺血透导管置管术,对比观察了横切、纵切以及横切定位纵切进针三种不同的超声引导方式对穿刺成功率和并发症及操作时间的影响。结果 336例患者中穿刺成功335例,成功率为99.7%,其中有1例因血管纤细颈内静脉穿刺置管失败,改行股静脉置管。本研究中所有病例均未发现严重并发症。颈动脉损伤发生率为0.9%。结论横切定位纵切进针的方式是血透导管置管术的最佳超声引导方式,成功率相似,并发症少,操作时间短,值得进一步观察和推广。  相似文献   
1000.
目的研究结直肠癌手术患者术后病理中癌结节的检出与患者预后的关系,探讨更加详细、合理的分期方法。 方法收集2012年1月至2013年12月于安徽医科大学第一附属医院普外科行结直肠癌切除术的361例患者的临床及随访资料,采用Kaplan-Meier生存曲线比较生存差异,COX单因素和多因素分析影响结直肠癌患者预后的相关因素。 结果术后病理中癌结节检出与否和肿瘤的分化程度、肿瘤的浸润深度(T)、pTNM分期、CEA、CA19-9相关,差异具有统计学意义(均P<0.05);单因素分析癌结节阴性患者生存时间长于癌结节阳性患者,差异具有统计学意义(χ2=10.805,P<0.05);将N0、N1c、N1和N2的患者进行生存比较,发现N1c和N1的患者之间差异无统计学意义(χ2=0.580,P>0.05);随着癌结节数目的增加,患者的生存预后越差;当把癌结节当成转移淋巴结时,得到新的分期与第八版TNM分期的生存比较存在差异:当对癌结节数目、转移淋巴结数目和总检出淋巴结数目进行研究时发现,随着阳性结节比值(癌结节数+转移淋巴结数)/(癌结节数+病理检出淋巴结总数)的增加,患者的预后也随之变差(59.4 vs. 58.2 vs. 36.0 vs. 28.7,χ2=15.389;P=0.002)。 结论癌结节的状态是影响结直肠癌患者预后的重要因素,将癌结节及转移淋巴结均定义为阳性结节后,阳性结节比值越高的患者预后越差;阳性结节比值可作为评估结直肠癌患者TNM分期中的重要补充,为指导日后治疗提供更准确的依据。  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