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   409974篇
  免费   55643篇
  国内免费   22919篇
耳鼻咽喉   7111篇
儿科学   7616篇
妇产科学   5372篇
基础医学   35405篇
口腔科学   5698篇
临床医学   63960篇
内科学   84752篇
皮肤病学   9713篇
神经病学   29288篇
特种医学   15682篇
外国民族医学   198篇
外科学   65157篇
综合类   44408篇
现状与发展   146篇
一般理论   27篇
预防医学   22749篇
眼科学   11444篇
药学   29067篇
  299篇
中国医学   15616篇
肿瘤学   34828篇
  2024年   1584篇
  2023年   8802篇
  2022年   12475篇
  2021年   16971篇
  2020年   16436篇
  2019年   11276篇
  2018年   16780篇
  2017年   15630篇
  2016年   16249篇
  2015年   20352篇
  2014年   30101篇
  2013年   27881篇
  2012年   24001篇
  2011年   26807篇
  2010年   23213篇
  2009年   24067篇
  2008年   18973篇
  2007年   17247篇
  2006年   19948篇
  2005年   17490篇
  2004年   11116篇
  2003年   9508篇
  2002年   8366篇
  2001年   9464篇
  2000年   9414篇
  1999年   10367篇
  1998年   8360篇
  1997年   8196篇
  1996年   7029篇
  1995年   6709篇
  1994年   4825篇
  1993年   3516篇
  1992年   3579篇
  1991年   3237篇
  1990年   2616篇
  1989年   2504篇
  1988年   2143篇
  1987年   1839篇
  1986年   1628篇
  1985年   1318篇
  1984年   891篇
  1983年   731篇
  1982年   626篇
  1981年   524篇
  1980年   440篇
  1979年   396篇
  1978年   328篇
  1977年   396篇
  1975年   277篇
  1972年   302篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
11.
目的 探讨右美托咪定联合综合体温保护对腔镜手术治疗老年恶性肿瘤患者苏醒期质量及免疫功能的影响。方法 选择择期行腔镜手术治疗的老年恶性肿瘤患者90例,随机均分为3组:对照组(C组)、体温保护组(T组)和体温保护联合右美托咪定组(T-D组),每组30例。C组常规体温保护,T组和T-D组综合体温保护;T-D组麻醉诱导前10 min泵注右美托咪定0.5 μg/kg。记录3组患者麻醉诱导开始时(T0)、手术开始30 min(T1)、60 min(T2)、90 min(T3)、120 min(T4)以及手术结束时(T5)的鼻咽温度;于T0、术后2 h(T6)、24 h(T7)和48 h(T8)时抽取静脉血标本,测定T淋巴细胞亚群(CD3+、CD4+和CD8+)和自然杀伤细胞(NK cell)水平;记录患者术中麻醉药物用量及苏醒期质量指标。结果 与T0比较,C组T2~T5时点鼻咽温度均明显降低(P < 0.05);与C组比较,T组和T-D组T2~T5时点鼻咽温度明显升高(P < 0.05)。与T0时点比较,C组、T组和T-D组T6、T7和T8时点CD3+和NK cell活性均明显降低(P < 0.05);C组在T6、T7和T8时点,T组和T-D组在T6和T7时点,CD4+活性均明显降低(P < 0.05)。与C组比较,T组和T-D组T6和T7时点CD3+细胞活性均明显升高(P < 0.05);T组在T7时点,T-D组在T6和T7时点,CD4+细胞活性均明显升高(P < 0.05);T组在T7时点,T-D组在T6、T7和T8时点,NK cell活性均明显升高(P < 0.05)。结论 采用体温保护措施联合右美托咪定能够维持老年恶性肿瘤患者的体温稳定,减少围手术期意外低体温(IPH)的发生,并有效提高患者苏醒期质量,减轻免疫抑制程度,加速患者早期恢复。  相似文献   
12.
宫腔积液指宫腔内液体积存(积水、积血或积脓),是绝经后女性常见体征之一,常于超声检查时发现。持续宫腔积液患者,需宫腔镜检查寻找病因。本文报道1例以宫腔积液为首发症状,经宫腔镜检查确诊为胃型宫颈腺癌的患者。通过病例回顾并文献复习,以期为更多绝经后宫腔积液及宫颈病变的诊断提供参考,避免漏诊及误诊。1病例资料患者67岁,女,主因"绝经18年,不规则阴道出血2月"于2020年5月就诊于首都医科大学附属北京妇产医院妇科微创中心。  相似文献   
13.
14.
15.
16.
Bone mineral density (BMD) is a highly heritable predictor of osteoporotic fracture. GWAS have identified hundreds of loci influencing BMD, but few have been functionally analyzed. In this study, we show that SNPs within a BMD locus on chromosome 14q32.32 alter splicing and expression of PAR-1a/microtubule affinity regulating kinase 3 (MARK3), a conserved serine/threonine kinase known to regulate bioenergetics, cell division, and polarity. Mice lacking Mark3 either globally or selectively in osteoblasts have increased bone mass at maturity. RNA profiling from Mark3-deficient osteoblasts suggested changes in the expression of components of the Notch signaling pathway. Mark3-deficient osteoblasts exhibited greater matrix mineralization compared with controls that was accompanied by reduced Jag1/Hes1 expression and diminished downstream JNK signaling. Overexpression of Jag1 in Mark3-deficient osteoblasts both in vitro and in vivo normalized mineralization capacity and bone mass, respectively. Together, these findings reveal a mechanism whereby genetically regulated alterations in Mark3 expression perturb cell signaling in osteoblasts to influence bone mass.  相似文献   
17.
BackgroundComminuted patellar fractures are not rare, and the ideal treatment method remains controversial. The present study was conducted to evaluate effects and compare complications of two different methods used to treat comminuted patellar fractures.MethodsFrom March 2010 to August 2016, 102 cases of 34-C2 or 34-C3 comminuted patellar fractures were treated at our hospital, wherein patients received two different treatments: titanium cable tension band with cerclage method (group A) and intrafragmentary screws with X-shaped plating technique (group B). At follow-ups, articular step-off, range of motion (ROM), Lysholm scores, time of union, and complications were recorded and analyzed. Radiographic and clinical data as well as rate of complications were statistically analyzed.ResultsIn total, 87 patients were included in the final analysis (n = 47 in group A and n = 40 in group B). No significant differences were noted in terms of cost of implant, age, gender, rate of 34-C3 fractures, rate of layered inferior pole fractures, postoperative articular step-off and union time. At 2-year follow-up, average Lysholm scores, ROM and rate of complications were (89.0 ± 4.5), (122°±12°) and (27.7%) in group A and (90.2 ± 3.9), (124°±11°) and (17.5%) in group B, respectively, with no significant differences (p > 0.05). The mean time of surgery in group B was shorter than that in group A with significant difference (p < 0.05).ConclusionsTreatment using the intrafragmentary screws and plate method for amenable comminuted patellar fractures achieved similar complication rate and favorable functional outcomes at the 2-year follow-up, which was comparable to the titanium cable tension band with cerclage method. Thus, the intrafragmentary screws and plate method is effective, safe and convenient for 34-C2/C3 comminuted patellar fractures, especially appropriate for patients with layered fragments.  相似文献   
18.
Near-infrared diffuse correlation spectroscopy/tomography (DCS/DCT) has recently emerged as a noninvasive measurement/imaging technology for tissue blood flow. In DCT studies, the high-dense collection of light temporal autocorrelation curves (g2(τ)) via fiber array are critical for image reconstruction of blood flow. Previously, the camera-based fiber array limits the field of view (FOV), precluding its applications on large-size human tissues. The line-shape fiber probe based on lens combination, which is predominantly used in current DCT studies, requires rotated-scanning over the surface of target tissue, substantially prolonging the measurement time and increasing the system instability. In this study, we design a noncontact optical probe for DCT based on collimating micro-lens fiber array, termed as FA-nc-DCT system. For each source/detector fiber, a single optical path was collimated by coupling with one micro-lens in the fiber array that is integrated in a square-shape base. Additionally, an 8×8 optical switch is used to share the hardware laser and detectors without spatial scanning. The FA-nc approach for the precise collection of g2(τ) curves was validated through a speed-varied phantom experiment and the human experiments of cuff occlusion, from which the expected value of the blood flow index (BFI) was obtained. Furthermore, the flow anomaly in the phantom and the ischemic muscle in human were accurately reconstructed from the FA-nc-DCT system, which is combined with the imaging framework based on the Nth-order linear algorithm that we recently created. Those outcomes demonstrated the great potential of FA-nc-DCT technology for fast and robust imaging of various diseases such as human breast cancers.  相似文献   
19.
20.
Over the last 40 years, the incidence and prevalence of gastroenteropancreatic neuroendocrine neoplasms (GEP-NENs) have continued to increase. Compared to other epithelial neoplasms in the same organ, GEP-NENs exhibit indolent biological behavior, resulting in more chances to undergo surgery. However, the role of surgery in high-grade or advanced GEP-NENs is still controversial. Surgery is associated with survival improvement of well-differentiated high-grade GEP-NENs, whereas poorly differentiated GEP-NENs that may benefit from resection require careful selection based on Ki67 and other tissue biomarkers. Additionally, surgery also plays an important role in locally advanced and metastatic disease. For locally advanced GEP-NENs, isolated major vascular involvement is no longer an absolute contraindication. In the setting of metastatic GEP-NENs, radical intended surgery is recommended for patients with low-grade and resectable metastases. For unresectable metastatic disease, a variety of surgical approaches, including cytoreduction of liver metastasis, liver transplantation, and surgery after neoadjuvant treatment, show survival benefits. Primary tumor resection in GEP-NENs with unresectable metastatic disease is associated with symptom control, prolonged survival, and improved sensitivity toward systemic therapies. Although there is no established neoadjuvant or adjuvant strategy, increasing attention has been given to this emerging research area. Some studies have reported that neoadjuvant therapy effectively reduces tumor burden, improves the effectiveness of subsequent surgery, and decreases surgical complications.  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