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   1571篇
  免费   127篇
  国内免费   10篇
耳鼻咽喉   47篇
儿科学   43篇
妇产科学   38篇
基础医学   296篇
口腔科学   5篇
临床医学   134篇
内科学   320篇
皮肤病学   42篇
神经病学   116篇
特种医学   44篇
外科学   216篇
综合类   25篇
一般理论   1篇
预防医学   126篇
眼科学   10篇
药学   119篇
中国医学   9篇
肿瘤学   117篇
  2024年   3篇
  2023年   10篇
  2022年   13篇
  2021年   38篇
  2020年   16篇
  2019年   41篇
  2018年   40篇
  2017年   30篇
  2016年   37篇
  2015年   34篇
  2014年   53篇
  2013年   72篇
  2012年   119篇
  2011年   148篇
  2010年   81篇
  2009年   64篇
  2008年   105篇
  2007年   108篇
  2006年   112篇
  2005年   98篇
  2004年   106篇
  2003年   85篇
  2002年   82篇
  2001年   10篇
  2000年   6篇
  1999年   18篇
  1998年   19篇
  1997年   18篇
  1996年   15篇
  1995年   16篇
  1994年   15篇
  1993年   18篇
  1992年   6篇
  1991年   6篇
  1989年   4篇
  1988年   2篇
  1987年   6篇
  1986年   5篇
  1985年   5篇
  1984年   3篇
  1983年   3篇
  1982年   12篇
  1981年   5篇
  1980年   4篇
  1979年   3篇
  1978年   4篇
  1977年   3篇
  1974年   2篇
  1971年   2篇
  1955年   1篇
排序方式: 共有1708条查询结果,搜索用时 46 毫秒
111.
Background and objective: The interrupter resistance (Rint) can be calculated from various estimates of alveolar pressure based on mouth pressure during occlusion. We compared Rint, as measured by the opening interrupter technique (Rint1), and the linear back‐extrapolation method (Rint2), with the ‘gold standard’ airway resistance measured by plethysmography (Raw). Methods: The study included 32 asthmatic children and 11 children with cystic fibrosis, aged 5 to 18 years, who were categorized into non‐obstructed (NObs) (n = 27) and obstructed (Obs) (n = 16) groups. Spirometry and the three different resistance measurements were performed on all children. Rint1 and Raw were assessed after a bronchodilator (BD) test in 16 and nine children, respectively, in the Obs group. Results: Raw (0.48 ± 0.20 kPa.s/L) was lower than Rint1 (1.04 ± 0.34 kPa.s/L) and Rint2 (0.63 ± 0.18 kPa.s/L) (P < 0.001). Raw, but neither Rint1 nor Rint2, was significantly higher in the Obs group than in the NObs group (0.57 ± 0.23 vs 0.42 ± 0.16 kPa.s/L, P < 0.05). The differences Rint1‐Raw and Rint2‐Raw were correlated with FEV1/VC (P < 0.01 and P < 0.001), and Rint1‐Raw was correlated with height (P < 0.001). After BD significant changes in Rint1 and Raw were observed in 5/9 and 7/9 children, respectively. Conclusions: Rint2, as well as Rint1, may be underestimated in the most Obs children and may therefore fail to detect severe obstruction. Rint1 is likely to include a non‐negligible contribution from the tissue component, especially in the youngest children. Although not different between Obs and NObs children at baseline, Rint1 did detect bronchodilation in some Obs children.  相似文献   
112.
We previously reported that exosomal nanoparticles secreted by human pancreatic tumoral cell lines decrease tumoral cell proliferation through the mitochondria‐dependent apoptotic pathway, because of activation of pro‐apoptotic phosphatase and tensin homolog deleted on chromosome 10 (PTEN) and of glucose synthase kinase‐3β (GSK‐3β). Interactions between exosomal nanoparticles and cells are thought to involve membrane lipid rafts. However, the underlying mechanism is unknown. Here, we report that the interaction of exosomal nanoparticles with pancreatic cancer cells led to decreased expression of hairy and enhancer‐of‐split homolog‐1 (Hes‐1), the intranuclear target of Notch‐1 signaling pathway, and to activation of the apoptotic pathway after a cell cycle arrest in G0G1 phase. Strikingly, the expression level of Notch‐1 pathway components was critical, because exosomal nanoparticles decreased the proliferation of cells in which these partners are either weakly represented, in differentiated adenocarcinoma cells, or inhibited, in poorly differentiated carcinoma cells, by blocking presenilin in the γ‐secretase complex that regulates the Notch‐1 pathway. Overexpression of Notch‐1 intracellular domain resulted in the reversion of the cell proliferation inhibition promoted by exosomal nanoparticles. Blocking presenilin unexpectedly resulted in activation of PTEN and GSK‐3β. Conversely, inhibiting either PTEN or GSK‐3β increased Hes‐1 expression and partially counteracted the inhibition of proliferation promoted by exosomal nanoparticles, highlighting reciprocal regulations between Notch signaling and PTEN/GSK‐3β. We concluded that interactions of exosomal nanoparticles with target cells, at lipid rafts where Notch‐1 pathway partners are localized, hampered the functioning of the Notch‐1 survival pathway and activated the apoptotic pathway, which determines tumoral cell fate. © 2009 UICC  相似文献   
113.
114.
Double supplementation in selenium and vitamin E during total parenteral nutrition (TPN) now appears essential to avoid clinical manifestations of their deficiencies. We studied children of 1 month to 12 years of age deficient in selenium (plasmatic selenium : P-Se : 40–80 μg/L) and vitamin E (ratio vitamin E on total lipids : VE/LT = 1.10 − 1.80 mg/g). Prior to supplementation, the ratio VE/LT is negatively correlated to P-Se (r = −0.81) and positively to erythrocyte selenium (RBC-Se, r = +0.64). These results suggest a balance between both. The parenteral alimentation was then supplemented with sodium selenite (3 μg/kg/d) and weekly with IM vitamin E (Protocol 1 : P1 : 30 to 60 mg according to age; Protocol 2 : P2 : twice these doses). The ratio VE/LT returned to normal faster in P2 than in P1 (P2 : 15–30 days; P1 : about 120 days). Selenium supplementation restores P-Se quickly (45–60 days) contrary to RBC-Se which is a slow process (120 d). High vitamin E intakes do not seem to have an effect upon selenium stores : no statistical differences were found between P1 and P2 during the same period. Such intakes may however be indicated during the first month of TPN to balance the time course for repletion of RBC-Se which is long (120 days).  相似文献   
115.
IntroductionPhysical therapy (PT) may reduce the pain associated with provoked vestibulodynia (PVD) based on previous findings that pelvic floor muscle dysfunction (PFMD) is associated with PVD symptoms.AimsThe goals of this study were: (i) to determine whether women with and without PVD differ on measures of pelvic floor muscle (PFM) behavior; and (ii) to assess the impact of PT treatment for women with PVD on these measures.MethodsEleven women with PVD and 11 control women completed an assessment evaluating PFM behavior using surface electromyography (SEMG) recordings and a digital intravaginal assessment. Women with PVD repeated the assessment after they had undergone eight PT treatment sessions of manual therapy, biofeedback, electrical stimulation, dilator insertions, and home exercises.Main Outcome MeasuresSuperficial and deep PFM SEMG tonic activity and phasic activity in response to a painful pressure stimulus, PFM digital assessment variables (tone, flexibility, relaxation capacity, and strength).ResultsAt pretreatment, women with PVD had higher tonic SEMG activity in their superficial PFMs compared with the control group, whereas no differences were found in the deep PFMs. Both groups demonstrated contractile responses to the painful pressure stimulus that were significantly higher in the superficial as compared with the deep PFMs, with the responses in the PVD group being higher than those in control women. Women with PVD had higher PFM tone, decreased PFM flexibility and lower PFM relaxation capacity compared with control women. Posttreatment improvements included less PFM responsiveness to pain, less PFM tone, improved vaginal flexibility, and improved PFM relaxation capacity, such that women with PVD no longer differed from controls on these measures.ConclusionWomen with PVD demonstrated altered PFM behavior when compared with controls, providing empirical evidence of PFMD, especially at the superficial layer. A PT rehabilitation program specifically targeting PFMD normalized PFM behavior in women with PVD. Gentilcore-Saulnier, E, McLean L, Goldfinger C, Pukall CF, and Chamberlain S. Pelvic floor muscle assessment outcomes in women with and without provoked vestibulodynia and the impact of a physical therapy program.  相似文献   
116.
The distribution of benzodiazepine binding sites was analysed in limbic structures of rat brain by quantitative radioautography of brain sections incubated with 3H-flunitrazepam (3H-FLU). Quantitative estimation of the binding parameters was made in each range of postero-anterior sections taken. Distribution of 3H-FLU binding sites was found to be rather homogeneous in most of the structures examined but there were regional differences which resulted from variations in the densities of sites rather than in their affinities. A particular distribution pattern of 3H-FLU binding sites was observed in the cingulate cortex contrasting with the homogeneous postero-anterior distribution measured in other cortical areas in the same slices. A significantly greater density of sites was found in the anterior part of the structure as compared to the posterior part. This difference, which corresponds to a change in the density of sites without alteration of their apparent affinity and occurs at a precise anatomical level, is discussed with reference to the anatomical organization of this brain structure and to its possible functional implications.  相似文献   
117.
Autoradiographic localization of kainate binding sites has been determined in developing human and rat hippocampi. The results suggest differences. In particular, a transient high density of sites occurs in the supragranular layer of the fascia dentata of the human hippocampus.  相似文献   
118.
发展健康城市项目的20个步骤   总被引:4,自引:1,他引:3  
健康城市项目是一个非常艰巨的项目。虽然 1 5年前世界卫生组织欧洲区就已启动健康城市项目 ,但时至今日这项目的实施还存在许多问题。把健康城市的理想转化为现实需要勇气、政治承诺和有志于革新与实验。建立公共卫生工作联盟 ,寻求健康促进新的资源 ,以及发展项目的策略和工作方法 ,并把其转化为具体方案和行动必须考虑不同的文化和传统 ,这是最具挑战性的任务之一[1] 。经过多年的欧洲健康城市项目实践 ,世界卫生组织概括总结了健康城市项目发展的基本步骤。一般而言 ,健康城市项目发展分为 3个阶段 :启动 ,组织 ,行动。这 3个阶段相互交…  相似文献   
119.
One hundred thirty-three strains of Pasteurella haemolytica of both biotypes (90 and 43 strains of biotypes A and T, respectively) and almost all the serotypes were subjected to ribotyping, random amplified polymorphic DNA (RAPD) analysis, and pulsed-field gel electrophoresis (PFGE) analysis for epidemiological purposes. A total of 15 patterns recorded as ribotypes HA to HO were found for the P. haemolytica biotype A strains, with ribotypes HA, HC, and HD being encountered most often (66 strains [74%]); and 20 ribotypes, designated HA′ to HT′, that were clearly distinct from those observed for biotype A strains were observed for strains of biotype T. RAPD analysis generated a total of 44 (designated Rp1 to Rp44) and 15 (designated Rp1′ to Rp 15′) unique RAPD patterns for biogroup A and biogroup T, respectively. Analysis of the data indicated that a given combined ribotype-RAPD pattern could be observed for biotype A strains of different serotypes, whatever the zoological or geographic origin, whereas this was not the case for biotype T strains. PFGE appeared to be more efficient in strain discrimination since selected strains from various zoological or geographical origins harboring the same ribotype-RAPD group were further separated into unique entities.  相似文献   
120.
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