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   1633篇
  免费   160篇
  国内免费   4篇
耳鼻咽喉   22篇
儿科学   41篇
妇产科学   16篇
基础医学   232篇
口腔科学   12篇
临床医学   202篇
内科学   303篇
皮肤病学   25篇
神经病学   85篇
特种医学   44篇
外科学   247篇
综合类   21篇
一般理论   1篇
预防医学   150篇
眼科学   98篇
药学   132篇
中国医学   15篇
肿瘤学   151篇
  2024年   2篇
  2023年   30篇
  2022年   77篇
  2021年   113篇
  2020年   57篇
  2019年   72篇
  2018年   71篇
  2017年   41篇
  2016年   47篇
  2015年   58篇
  2014年   92篇
  2013年   107篇
  2012年   123篇
  2011年   100篇
  2010年   67篇
  2009年   62篇
  2008年   84篇
  2007年   77篇
  2006年   76篇
  2005年   73篇
  2004年   53篇
  2003年   50篇
  2002年   47篇
  2001年   31篇
  2000年   19篇
  1999年   18篇
  1998年   14篇
  1997年   7篇
  1996年   6篇
  1994年   6篇
  1993年   9篇
  1992年   14篇
  1991年   10篇
  1990年   12篇
  1989年   8篇
  1988年   11篇
  1987年   8篇
  1986年   9篇
  1985年   5篇
  1984年   5篇
  1983年   6篇
  1982年   2篇
  1981年   3篇
  1980年   2篇
  1979年   3篇
  1977年   1篇
  1976年   2篇
  1975年   2篇
  1974年   1篇
  1973年   2篇
排序方式: 共有1797条查询结果,搜索用时 15 毫秒
1.
Congenital rubella syndrome (CRS) results from maternal rubella virus infection in early pregnancy. Abnormal neuroimaging findings have been analyzed in a small number of CRS patients in the past; however, their clinical significance has been poorly addressed. Therefore, we have investigated the neuroimaging findings of 31 patients with CRS from previous studies. The most common finding was parenchymal calcification, which was observed in 18 of 31 patients (58.1%). A multivariable logistic regression model showed that it was associated with psychomotor or mental retardation (p = 0.018), suggesting that parenchymal calcification in CRS could be a prognostic factor.  相似文献   
2.
Genetic and epigenetic alterations importantly contribute to the pathogenesis of lung cancer. In the study, we measured the frequency and distribution of molecular abnormalities of EGFR as well as the aberrant promoter methylations of BRCA1, MGMT, MLH1, and RASSF1A in Vietnamese lung adenocarcinomas. We investigated the association between genetic and epigenetic alteration, and between each abnormality with clinicopathologic parameters. Somatic EGFR mutation that was found in 49/139 (35.3%) lung adenocarcinomas showed a significant association with young age, female gender, and non-smokers. EGFR overexpression was identified in 82 tumors (59.0%) and statistical relationships with EGFR or BRCA1 methylation but not EGFR mutation. In addition, EGFR, BRCA1, MGMT, MLH1, and RASSF1A methylations were found in 33 (23.7%), 41 (29.5%), 46 (33.1%), 28 (20.1%), and 41 (29.5%) cases of a total of 139 lung adenocarcinomas, respectively. The RASSF1A methylation was found to be linked to the smoking habit. Methylations in MGMT and RASSF1A were also found to correlate with metastasis status. Furthermore, the distribution of EGFR mutation and that of BRCA1, MGMT or RASSF1A methylation were significantly exclusive in lung adenocarcinomas. The main finding of our study demonstrate that epigenetic abnormalities might play a critical role for the lung tumorigenesis in patients with smoking history and metastasis, and partly affect the predictive value of EGFR mutations through blocking expression due to promoter EGFR hypermethylation. Mutually exclusive distribution of genetic and epigenetic alterations reflects differently biological characteristics in the etiology of lung adenocarcinomas.  相似文献   
3.
4.
5.
6.
A 40-year-old woman who ingested a 35% hydrogen peroxide solution presented to the emergency department with abdominal pain. Acute abdominal series showed gas in the portal vein system. The patient was admitted and treated conservatively. She was released after five days in the hospital with no major sequelae.  相似文献   
7.
Previous research has demonstrated that 2-item versions of subscales from the Chronic Pain Coping Inventory, Coping Strategy Questionnaire, and the Survey of Pain Attitudes appear adequately reliable and valid for use in studies with large sample sizes. It was suggested that use of the abbreviated scales might help to expand the testing and application of cognitive-behavioral models of pain to new settings and with new populations where assessment burden might be a key issue. This study explored the utility of these brief scales among veterans in a Veterans Affairs setting. Strong associations were found between the 2-item versions and their respective parent scales. In addition, the 2-item scales were found to be associated with other pain-related measures, supporting their predictive validity. The results of this study replicate previous findings and offer support for the use of the 2-item versions for both screening and research purposes in Veterans Affairs settings with a veteran population. PERSPECTIVE: This article presents the psychometric properties of brief versions of 3 commonly used pain coping and belief questionnaires in a unique population. These measures could be used clinically for initial screening purposes, as well as for treatment monitoring.  相似文献   
8.
n-Hexacosanol (hexa), a long chain fatty alcohol extracted from Hygrophila erecta, has proved to possess neurotrophic activities on cultured neurons, and to attenuate the degeneration of cholinergic neurons after injury. In the present study, we show that hexa has also interesting properties on macrophages, a cell type largely represented in the brain: when added to mice resident peritoneal macrophages, it provokes significant morphological changes, and increases their phagocytosis capacity. These results may indicate that some membrane properties involved in these different effects and in macrophage functions are affected by n-hexacosanol, but other sites of action could also be considered.  相似文献   
9.
BACKGROUND.: Mercuric chloride (HgCl2 induces a lymphoproliferative disorderand autoimmune glomerulonephritis in Brown Norway (BN) rats.This syndrome is the consequence of T cell-dependent polyclonalB cell activation and autoantibody production. We have previouslyshown that HgCl2-induced autoimmune perturbations can be preventedin BN rats by the administration of cyclosporin A (CsA). Themost potent vitamin D3 metabolite 1,25(OH)2 D3 (Vit D3) sharescertain immunomodulatory properties with CsA. We therefore choseto compare the effects of Vit D3 to those of CsA in BN ratstreated with HgCl2 in order to establish whether Vit D3 eitheralone or in combination with CsA can attenuate an autoimmunesyndrome in vivo. METHODS.: BN rats were treated with HgCl2 according to a standard protocol.Subgroups of rats were also given CsA alone, Vit D3 or syntheticanalogues of Vit D3 alone, or combinations of both agents. Differentdoses and routes of administration were compared. The followingmarkers of disease activity were evaluated: mortality, peakproteinuria, serum IgE concentrations, and renal immunoglobulindeposition. RESULTS.: Disease activity was markedly attenuated in all rats treatedwith CsA alone. Vit D3 and certain of its synthetic analoguesadministered alone also tempered the autoimmune process, butto a lesser extent than did CsA. The effect of CsA alone wasso potent, that no additive or synergistic effects could bedemonstrated when CsA was administered in combination with VitD3. CONCLUSIONS.: Despite similar described immunomodulatory effects in vitro,CsA is clearly more effective than Vit D3 in preventing HgCl2autoimmune disease in BN rats. This suggests that there is adifference in the cellular targets of these two agents in vivo,and/or a difference in the potency with which HgCl2-triggeredimmune activation is suppressed.  相似文献   
10.
Addition polymerization of hydroxytelechelic polybutadiene (HTPB) with hexamethylene diisocyanate (HMDI) with a mole ratio NCO/OH = 0,8 in dilute solution of toluene as well as in bulk follows apparent 3rd order kinetics. The polymerization rates are twice as sensitive to temperature as in toluene, an effect which is attributed to intra- and/or intermolecular (OH, OH) auto-association. The three alcoholic functions in HTPB are catalyzed equally by dibutyltin dilaurate. Even with high excess of NCO, free alcoholic functions were found in the product. They were determined quantitatively in moulded polyurethane sheets from HTPB + HMDI and HTPB + 4,4′-methylenedi(phenyl isocyanate) which should be partially crosslinked:  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