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   20787篇
  免费   990篇
  国内免费   113篇
耳鼻咽喉   342篇
儿科学   326篇
妇产科学   177篇
基础医学   2543篇
口腔科学   461篇
临床医学   1307篇
内科学   5467篇
皮肤病学   383篇
神经病学   2044篇
特种医学   831篇
外科学   3182篇
综合类   94篇
预防医学   812篇
眼科学   462篇
药学   1365篇
中国医学   47篇
肿瘤学   2047篇
  2023年   96篇
  2021年   305篇
  2020年   168篇
  2019年   232篇
  2018年   302篇
  2017年   245篇
  2016年   289篇
  2015年   348篇
  2014年   458篇
  2013年   615篇
  2012年   913篇
  2011年   998篇
  2010年   542篇
  2009年   516篇
  2008年   944篇
  2007年   1047篇
  2006年   1125篇
  2005年   1114篇
  2004年   1085篇
  2003年   1031篇
  2002年   1092篇
  2001年   769篇
  2000年   803篇
  1999年   692篇
  1998年   283篇
  1997年   260篇
  1996年   225篇
  1995年   203篇
  1994年   169篇
  1993年   164篇
  1992年   441篇
  1991年   410篇
  1990年   364篇
  1989年   394篇
  1988年   360篇
  1987年   320篇
  1986年   282篇
  1985年   282篇
  1984年   218篇
  1983年   185篇
  1982年   103篇
  1981年   95篇
  1980年   83篇
  1979年   142篇
  1978年   115篇
  1977年   88篇
  1974年   92篇
  1973年   93篇
  1972年   87篇
  1971年   85篇
排序方式: 共有10000条查询结果,搜索用时 46 毫秒
1.
Irritable bowel syndrome (IBS) is an important health care concern. Alterations in the microbiota of the gut-brain axis may be linked to the pathophysiology of IBS. Some dietary intake could contribute to produce various metabolites including D-amino acids by the fermentation by the gut microbiota. D-amino acids are the enantiomeric counterparts of L-amino acids, in general, which could play key roles in cellular physiological processes against various oxidative stresses. Therefore, the presence of D-amino acids has been shown to be linked to the protection of several organs in the body. In particular, the gut microbiota could play significant roles in the stability of emotion via the action of D-amino acids. Here, we would like to shed light on the roles of D-amino acids, which could be used for the treatment of IBS.  相似文献   
2.
3.

Background

There were few studies assessed the postoperative sarcopenia in patients with cancers. The objective of present study was to assess whether postoperative development of sarcopenia could predict a poor prognosis in patients with adenocarcinoma of esophagogastric junction, (AEG) and upper gastric cancer (UGC).

Methods

Patients with AEG and UGC who were judged as non-sarcopenic before surgery were reassessed the presence of postoperative development of sarcopenia 6 months after surgery. Patients were divided into the development group or non-development group, and clinicopathological factors and prognosis between these two groups were analyzed.

Results

The 5-year overall survival rates were significantly poorer in the development group than non-development group (68.0% vs. 92.6%, P?=?0.0118). Multivariate analyses showed that postoperative development of sarcopenia was an independent prognostic factor for poor overall survival (P?=?0.0237).

Conclusions

Postoperative development of sarcopenia was associated with a poor prognosis in patients with AEG and UGC.  相似文献   
4.

Background

Myelin oligodendrocyte glycoprotein antibodies (MOG Abs) are frequently detected in pediatric acquired demyelinating syndrome (ADS), and MOG-Ab-positive ADS differs from multiple sclerosis (MS) and aquaporin-4 (AQP4)-Ab-positive neuromyelitis optica spectrum disorder (NMOSD) in terms of age distribution, therapeutic response, and prognosis.

Methods

Based on medical records, we retrospectively evaluated patients with MOG-Ab-positive NMOSD treated in the acute phase who were followed up in the chronic phase at our hospital from January 2011 to December 2017.

Results

The patients comprised two boys and two girls aged 3–12 (median, 8) years. Peak MOG-Ab titers were 1:2048 to 1:32768 (median, 1:10240), and the relapse rate ranged from 0 to 1.25 times/year (median, 0.59 times/year); no sequelae were observed in any cases. Lesions other than those of optic neuritis were distributed at the cortex in one patient, subcortical white matter in four, deep white matter in three, and brainstem in one, all of which were disseminated lesions. No lesions were found in the corpus callosum, periventricular white matter, diencephalon, and regions adjacent to the third and fourth ventricles. The lesions tended to be asymptomatic, and two patients aged >5?years had well-demarcated lesions.

Conclusion

All the patients showed disseminated lesions in the subcortical region to deep white matter, which were different from those found in MS and AQP4-Ab-positive NMOSD and were consistent with the characteristics of brain lesions in MOG-Ab-positive ADS, including other disease types.  相似文献   
5.
Syphilis is a sexually transmitted disease caused by Treponema pallidum. Syphilitic aortitis might coexist in a dysfunctional aortic valve, but the etiology remains unclear, because microbiological diagnosis is difficult. A 62-year-old man with low-grade fever was diagnosed with aortitis and infective endocarditis, due to Treponema pallidum infection, using polymerase chain reaction analysis. This case suggests that syphilis might cause infective endocarditis.  相似文献   
6.
7.
8.
Cancer stem cells (CSCs) play a decisive role in the development and progression of cancer. To investigate CSCs in Epstein‐Barr virus (EBV)‐associated carcinoma (EBVaGC), we screened previously reported stem cell markers of gastric cancer in EBV‐infected gastric cancer cell lines (TMK1 and NUGC3) and identified CD44v6v9 double positive cells as candidate CSCs. CD44v6/v9+/+ cells were sorted from EBVaGC cell line (SNU719) cells and EBV‐infected TMK1 cells and these cell populations showed high spheroid‐forming ability and tumor formation in SCID mice compared with the respective CD44v6/v9?/? cells. Sphere‐forming ability was dependent on the nuclear factor‐κB (NF‐κB) signaling pathway, which was confirmed by decrease of sphere formation ability under BAY 11‐7082. Small interfering RNA knockdown of latent membrane protein 2A (LMP2A), one of the latent gene products of EBV infection, decreased spheroid formation in SNU719 cells. Transfection of the LMP2A gene increased the sphere‐forming ability of TMK1 cells, which was mediated through NF‐κB signaling. Together, these results indicate that CD44v6v9+/+ cells are CSCs in EBVaGC that are maintained through the LMP2A/NF‐κB pathway. Future studies should investigate CD44v6/v9+/+ cells in normal and neoplastic gastric epithelium to prevent and treat this specific subtype of gastric cancer infected with EBV.  相似文献   
9.
There is increasing evidence showing that clinicians employ different management strategies in their use of The Bethesda System for Reporting Thyroid Cytopathology (TBSRTC). In this meta-analysis, we investigated the differences in diagnosis frequency, resection rate (RR), and risk of malignancy (ROM) between Western (ie, American and European) and Asian cytopathology practices. We searched PubMed and Web of Science from January 2010 to January 2019. Proportion and 95% CIs were calculated using a random-effect model. We used independent sample t tests to compare frequencies, RR, and ROM between Western and Asian practices. We analyzed a total of 38 studies with 145,066 fine-needle aspirations. Compared with Asian practice, Western series had a significantly lower ROM in most of TBSRTC categories, whereas the RR was not statistically different. Focusing on indeterminate nodules, the RR in Western series was significantly higher (51.3% vs 37.6%; P = .048), whereas the ROM was significantly lower (25.4% vs 41.9%; P = .002) compared with those in Asian series. The addition of Asian cohorts increased ROM for most of diagnostic categories compared with the original TBSRTC. In conclusion, this study demonstrates a difference in Western and Asian thyroid cytology practice, especially regarding the indeterminate categories. Lower RR and higher ROM suggest that Asian clinicians adopt a more conservative approach, whereas immediate diagnostic surgery is favored in Western practice for indeterminate nodules. The addition of Asian series into a meta-analysis of TBSRTC altered ROM for several categories, which should be considered in future revisions of TBSRTC.  相似文献   
10.
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