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   23149篇
  免费   2354篇
  国内免费   1163篇
耳鼻咽喉   168篇
儿科学   287篇
妇产科学   315篇
基础医学   4424篇
口腔科学   479篇
临床医学   1789篇
内科学   4523篇
皮肤病学   566篇
神经病学   1227篇
特种医学   442篇
外国民族医学   12篇
外科学   3004篇
综合类   3077篇
现状与发展   5篇
预防医学   888篇
眼科学   342篇
药学   2124篇
  3篇
中国医学   341篇
肿瘤学   2650篇
  2024年   29篇
  2023年   489篇
  2022年   671篇
  2021年   1716篇
  2020年   1175篇
  2019年   1437篇
  2018年   1272篇
  2017年   1010篇
  2016年   819篇
  2015年   961篇
  2014年   1402篇
  2013年   1279篇
  2012年   1288篇
  2011年   1458篇
  2010年   1246篇
  2009年   1301篇
  2008年   1227篇
  2007年   1131篇
  2006年   1010篇
  2005年   821篇
  2004年   679篇
  2003年   546篇
  2002年   345篇
  2001年   371篇
  2000年   282篇
  1999年   246篇
  1998年   254篇
  1997年   217篇
  1996年   145篇
  1995年   168篇
  1994年   146篇
  1993年   118篇
  1992年   110篇
  1991年   94篇
  1990年   70篇
  1989年   77篇
  1988年   72篇
  1987年   61篇
  1986年   60篇
  1985年   106篇
  1984年   108篇
  1983年   77篇
  1982年   85篇
  1981年   90篇
  1980年   85篇
  1979年   59篇
  1978年   69篇
  1977年   32篇
  1976年   47篇
  1975年   32篇
排序方式: 共有10000条查询结果,搜索用时 78 毫秒
31.
目的探讨膝关节骨软骨损伤评估、治疗方法以及疗效。方法2010 年 1 月—2016 年 1 月,收治 17 例膝关节骨软骨损伤患者。男 2 例,女 15 例;年龄 15~33 岁,平均 19.3 岁。致伤原因:扭伤 14 例,膝关节过伸、内翻暴力致伤 3 例。骨软骨骨折部位:髌骨 8 例,股骨外髁 4 例,股骨内髁 1 例,胫骨平台 4 例。新鲜骨折 15 例,陈旧性骨折 2 例。术前膝关节 Lysholm 评分为(31.6±2.3)分。14 例骨软骨骨折切开复位后,根据骨质情况分别选择可吸收棒(9 例)、可吸收软骨钉(3 例)或可吸收缝线(2 例)固定;3 例骨块位于胫骨内侧平台边缘非负重区直接取出。结果术后 1 例发生切口脂肪液化,再次清创后愈合;其余患者切口均Ⅰ期愈合。患者均获随访,随访时间 6 个月~2 年,平均 13 个月。14 例行内固定患者中,13 例骨折愈合良好,1 例髌骨骨软骨骨折未愈合;3 例非负重区骨软骨取出患者,随访期间未见膝关节内侧关节间隙变窄及创伤性关节炎发生。术后 1 年,膝关节 Lysholm 评分为(91.3±1.1)分,较术前明显改善(t=7.136,P=0.001)。 结论对于膝关节骨软骨损伤,骨软骨骨块带有全层松质骨时可选择切开复位内固定,带点状松质骨时可直接取出。  相似文献   
32.
33.
34.
35.
36.
In order to evaluate the in vivo effect of inhaled formulations, it is a gold standard to create a lung metastasis model by intravenously injecting cancer cells into an animal. Because the cancer grows from the blood vessel side, there is a possibility of underestimating the effect of an inhaled formulation administered to the lung epithelium side. In addition, the metastasis model has disadvantages in terms of preparation time and expense. The present study aimed to establish a new method to evaluate the effect of an inhaled small interfering RNA (siRNA) formulation that is more correct, more rapid, and less expensive. We investigated whether siRNA can suppress gene expression of plasmid DNA (pDNA) by serial pulmonary administration of siRNA and pDNA powders prepared by spray-freeze-drying. We revealed that formulations of dry siRNA powder significantly suppressed gene expression of pDNA powder compared with a control group with no siRNA. Naked siRNA inhalation powder with no vector showed the suppression of gene expression equivalent to that of an siRNA-polyethyleneimine complex without damaging tissues. These results show that the present method is suitable for evaluating the gene-silencing effect of inhaled siRNA powders.  相似文献   
37.
miR-30c has been acknowledged as a tumor suppressor in various human cancers, such as ovarian cancer, gastric cancer, and prostate cancer. However, the role of miR-30c in glioblastoma (GBM) needs to be investigated. In our study, we found that the expression of miR-30c was significantly downregulated in GBM tissues and cell lines. We found that overexpression of miR-30c inhibited cellular proliferation of GBM cells in vitro and in vivo. More GBM cells were arrested in the G0 phase after miR-30c overexpression. Moreover, we showed that miR-30c overexpression suppressed the migration and invasion of GBM cells. Mechanistically, we found that SOX9 was a direct target of miR-30c in GBM cells. Overexpression of miR-30c inhibited the mRNA and protein levels of SOX9 in GBM cells. Moreover, there was a negative correlation between the expression of miR-30c and SOX9 in GBM tissues. Finally, we showed that restoration of SOX9 in GBM cells reversed the proliferation, migration, and invasion of GBM cells transfected with miR-30c mimic. Collectively, our results demonstrated that miR-30c suppressed the proliferation, migration, and invasion of GBM cells via targeting SOX9.  相似文献   
38.
MicroRNAs (miRNAs) have been found to be aberrantly expressed and exert essential roles in the tumorigenesis and progression of gastric cancer (GC). miR-301b-3p has been recognized as a cancer-related miRNA in lung cancer, bladder cancer and hepatocellular carcinoma. However, the function of miR-301b-3p in GC progression and its underlying mechanism have not been studied yet. In this study, we found that miR-301b-3p expression was up-regulated in GC tissues compared to adjacent noncancerous tissues. Furthermore, the elevated levels of miR-301b-3p were detected in GC cell lines (SGC-7901, AGS, MKN-45 and MGC-803) as compared with GES-1 cells. Interestingly, GC tissues from patients with tumor size ≥ 5 cm and advanced tumor stages showed obvious higher levels of miR-301b-3p compared to matched controls. Functionally, miR-301b-3p knockdown prominently inhibited cell proliferation, and induced cell cycle arrest at G1 phase and apoptosis in MGC-803 cells. Meanwhile, ectopic expression of miR-301b-3p conversely regulated these biological behaviors of MKN-45 cells. Next, we found that miR-301b-3p knockdown increased, whereas miR-301b-3p overexpression reduced the expression of zinc finger and BTB domain containing 4 (ZBTB4) in GC cells. Accordingly, luciferase reporter assay identified ZBTB4 as a direct target of miR-301b-3p. ZBTB4 overexpression markedly restrained the growth of MGC-803 cells. More importantly, ZBTB4 silencing partially reversed miR-301b-3p knockdown-induced tumor suppressive effects on MGC-803 cells. In conclusion, we firstly revealed that miR-301-3p was highly expressed in GC and contributed to tumor progression via attenuating ZBTB4, which might provide a novel molecular-targeted strategy for GC treatment.  相似文献   
39.
Recent studies have shown that intratumoral heterogeneity is prevalent in esophageal squamous cell cancer (ESCC) based on DNA sequencing and chromosome analysis in multiple regions from the same tumor. This study aimed to investigate the expression of ZNF750, EP300, MTOR and KMT2D and their intratumoral heterogeneity (ITH) in patients with ESCC. A total of 106 cases, who underwent esophagectomy from 2008 to 2010, with two foci from each case, were tested by immunohistochemistry(IHC) as well as 12 cases were tested by RNAscope in this study.We found that 58/106 (54.72%), 66/106 (62.26%), 75/106 (70.75%%) of ESCC showed high expression of ZNF750, EP300, MTOR, respectively by IHC, and 8/12 (66.67%), 10/12 (83.33%), 4/12 (33.33%) and 6/12 (50%) showed high expression of ZNF750, EP300, MTOR and KMT2D, respectively by RNAscope. Multivariate analysis showed that MTOR expression was an independent infavorable prognostic factor of overall survival (OS) (HR?=?1.921; P?=?0.000). This study also found that 44/106(4151%), 37/106 (34.91%), 39/106(36.79%) of ESCC showed heterogeneous expression of ZNF750, EP300 and MTOR respectively by IHC, 8/12(66.67%), 8/12(66.67%), 4/12(33.33%), 4/12(33.33%) of ZNF750, EP300, MTOR and KMT2D respectively by RNAscope, IHC and RNAscope could successfully detect a high prevalence of ITH. In conclusion, findings of this study showed that ZNF750, EP300, MTOR and KMT2D heterogeneously expressed in ESCC. High expression of ZNF750 related to a better outcome, while EP300 and MTOR related to a poor prognosis.  相似文献   
40.
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