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   4950篇
  免费   474篇
  国内免费   136篇
耳鼻咽喉   47篇
儿科学   130篇
妇产科学   71篇
基础医学   726篇
口腔科学   140篇
临床医学   492篇
内科学   836篇
皮肤病学   95篇
神经病学   334篇
特种医学   186篇
外国民族医学   1篇
外科学   538篇
综合类   326篇
现状与发展   1篇
预防医学   385篇
眼科学   132篇
药学   441篇
  2篇
中国医学   81篇
肿瘤学   596篇
  2024年   5篇
  2023年   80篇
  2022年   212篇
  2021年   221篇
  2020年   150篇
  2019年   197篇
  2018年   179篇
  2017年   160篇
  2016年   176篇
  2015年   206篇
  2014年   235篇
  2013年   265篇
  2012年   336篇
  2011年   348篇
  2010年   187篇
  2009年   169篇
  2008年   248篇
  2007年   260篇
  2006年   231篇
  2005年   274篇
  2004年   203篇
  2003年   170篇
  2002年   153篇
  2001年   103篇
  2000年   92篇
  1999年   79篇
  1998年   47篇
  1997年   53篇
  1996年   41篇
  1995年   33篇
  1994年   35篇
  1993年   28篇
  1992年   46篇
  1991年   49篇
  1990年   31篇
  1989年   30篇
  1988年   36篇
  1987年   28篇
  1986年   26篇
  1985年   19篇
  1984年   11篇
  1983年   5篇
  1982年   10篇
  1981年   6篇
  1979年   7篇
  1974年   5篇
  1972年   8篇
  1970年   8篇
  1969年   8篇
  1939年   4篇
排序方式: 共有5560条查询结果,搜索用时 15 毫秒
71.
Leptin and asthma in overweight children at 12 years of age   总被引:1,自引:0,他引:1  
Obesity is suggested as a risk factor for asthma, but the mechanisms are unclear. The relationship between obesity and asthma has not been considered in children born with very low-birth weight (VLBW). We hypothesized that overweight was a contributing factor for asthma in VLBW children, and that leptin and leptin-associated cytokines might play roles in overweight-related asthma. Seventy-four VLBW and 64 normal birth weight (NBW) children participated in a 12-yr follow up study assessing asthma and allergy. Twenty-seven (12 VLBW) of the 138 children were overweight according to the proposed international definition. The diagnosis of current asthma was made by a pediatrician. Serum levels of leptin and interferon (IFN)-gamma were analyzed by enzyme-linked immunosorbent assay (ELISA). Leptin levels were considerably higher in the overweight than in the non-overweight children (median value: 18.1 vs. 2.8 ng/ml, p < 0.001). In the overweight children, current asthmatics had twice as high levels of leptin as children without current asthma (median value: 30.8 vs. 14.3 ng/ml, p = 0.14), but this was not the case in the non-overweight children. IFN-gamma was more often detected in the overweight than in the non-overweight children (61% vs. 12%, p < 0.001), and there was a positive correlation between the levels of leptin and the levels of IFN-gamma (Rho = 0.40, p < 0.001). In the VLBW group, the overweight children had a significantly increased risk for current asthma compared with the non-overweight children after adjustment for the neonatal risk factors [adjusted odds ratio (OR) 5.8, 95% confidence interval (CI): 1.2-27]. Thus, overweight was associated with asthma in the VLBW children. Our hypothesis remained that leptin might be involved in the pathogenesis of asthma in the overweight children, and IFN-gamma might be a pathway in the process of leptin-induced inflammation.  相似文献   
72.
葡萄糖酸依诺沙星溶液的稳定性研究   总被引:4,自引:0,他引:4  
麦曦  廖一静  刘超 《药品评价》2004,1(1):37-38
目的考察葡萄糖酸依诺沙星溶液的稳定性。方法采用紫外分光光度法测定溶液中葡萄糖酸依诺沙星含量,HPLC法测定有关物质含量,考察了不同pH值的葡萄糖酸依诺沙星溶液在光照及高温条件下的质量变化。结果葡萄糖酸依诺沙星溶液在光照下易变色pH值5.5~6.0溶液在高温、光照5d后即出现结晶。pH值3.0~4.0溶液在光照条件下含量下降较多,有关物质增加较多。pH在4.0~5.5之间的葡萄糖酸依诺沙星溶液稳定性较好。结论本品应遮光保存,液体制剂的pH值范围确定在4.0~5.5之间较好。  相似文献   
73.
生殖健康促进   总被引:10,自引:0,他引:10  
健康促进最早是由医学史家Henry E.Sigerist于1945年提出来的[1]。他指出我们应该通过提供适宜的生活标准,良好的劳动条件、教育、物质文化以及休闲方式来促进健康。目前,普遍为大家所接受的健康促进的定义为“健康促进是促使人们维持和改善他们自身健康的过程[2]。”这个定义是一个包含社会和政治综合性的过程。它不仅仅是加强个人的技能和能力,还包括改变社会、环境和经济的条件来减少它们对大众和个人健康的影响。所以,健康促进是增强人们对健康决定因素的控制能力,从而改善其健康的过程。作为健康重要组成部分的生殖健康同样也受到了…  相似文献   
74.
Alteration of actin polymerization and loss of actin filaments is a marker of cellular dedifferentiation and early malignant transformation. To study this phenomenon, an in vitro human urothelial model consisting of two cell lines, HUC-PC and MC-T11, were incorporated into the study design. These two cell lines have different malignant transformation potential. The effect of green tea extract (GTE), a potential anticancer agent, on actin remodeling was investigated. Upon exposure to the carcinogen 4-aminobiphenyl (4-ABP), the untransformed HUC-PC undergoes malignant transformation whereas the transformed MC-T11 progresses from noninvasive to invasive tumor. GTE induces actin polymerization in MC-T11 cells in a dose-responsive manner, but this effect is less obvious in the untransformed, more differentiated HUC-PC cells, which natively have higher actin polymerization status. In contrast, GTE antagonizes carcinogen 4-ABP induced actin depolymerization and stress fiber disruption in HUC-PC cells. In MC-T11 cells, GTE inhibits 4-ABP induced motility by increasing cell adhesion and focal adhesion complex formation. The effect of GTE on actin remodeling seems to be mediated by the stimulation of small GTP-binding protein Rho activity, because C3 exoenzyme, a specific inhibitor for Rho, blocks GTE-mediated Rho activation and stress fiber formation in MC-T11 cells. This study shows that GTE exerts an effect on cytoskeletal actin remodeling and provides further support for the use of GTE as a chemopreventive agent.  相似文献   
75.
76.
77.
In man, COX (cytochrome c oxidase) deficiency is reported to be related to mutation of the SCO2 (synthesis of cytochrome c oxidase 2) gene, which encodes one of the copper-donor chaperones involved in the assembly of mitochondrial cytochrome c oxidase. Such COX deficiency due to the genetic condition leads to heart disease and the Leigh syndrome and is frequently fatal in childhood. Synthesis of cytochrome c oxidase X (SCOX) is a Drosophila orthologue of human SCO2. Here, we generated SCOX-knockdown flies and the full length SCOX transgenic flies to investigate the in vivo roles of SCOX. Our results demonstrated knockdown of SCOX gene in all cells and tissues to be associated with lethality at larval or pupal stages and this correlated with a decrease in ATP level. In contrast, the full length SCOX transgenic flies showed a longer lifespan than wild type flies and control flies carrying Act5C-GAL4 alone and this correlated with an increase in ATP level. Finally, when cultured on paraquat-added medium, full length SCOX transgenic flies also exhibited an elongated lifespan. Therefore, we hypothesized that SCOX plays an important role in ATP production and consumption, which helps to prevent production of mitochondrial reactive oxygen species and/or impairment of mitochondrial activity under oxidative stress.  相似文献   
78.
Calcifying pseudoneoplasm of the neuraxis (CAPNON) is a rare benign tumor of uncertain etiology, arising in the craniospinal axis. CAPNON typically arises in isolation, with only two prior reports of a concurrent second neoplasm. Here, we report the case of a male 17‐year‐old who presented with new‐onset seizures. MRIs revealed a 2 cm extra‐axial solid‐cystic mass, arising at the left temporo‐occipital junction and abutting the dura with marked surrounding parenchymal vasogenic edema. The solid components demonstrated dense calcification and avid enhancement. Gross total surgical resection was performed. Histopathological examination revealed central regions showing characteristic features of CAPNON. Toward the periphery, the CAPNON was intimately associated with and sharply demarcated from a meningioma, which showed up to five mitoses per 10 high‐power fields and had invasion into the adjacent brain parenchyma, warranting a WHO grade II designation. This is the first report of CAPNON arising in association with a meningioma. The coexistence of these two tumors raises the possibility of a reactive/dysplastic etiology for CAPNON.  相似文献   
79.
80.
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