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   3385159篇
  免费   252215篇
  国内免费   5016篇
耳鼻咽喉   47167篇
儿科学   111103篇
妇产科学   93833篇
基础医学   491720篇
口腔科学   96801篇
临床医学   305968篇
内科学   649234篇
皮肤病学   74112篇
神经病学   270131篇
特种医学   129201篇
外国民族医学   902篇
外科学   508949篇
综合类   76508篇
现状与发展   13篇
一般理论   1299篇
预防医学   267306篇
眼科学   79317篇
药学   253624篇
  13篇
中国医学   6359篇
肿瘤学   178830篇
  2018年   35772篇
  2017年   27245篇
  2016年   30533篇
  2015年   34723篇
  2014年   48784篇
  2013年   73907篇
  2012年   101081篇
  2011年   107344篇
  2010年   63773篇
  2009年   60482篇
  2008年   101339篇
  2007年   107750篇
  2006年   108947篇
  2005年   106003篇
  2004年   102524篇
  2003年   98208篇
  2002年   95840篇
  2001年   151204篇
  2000年   155956篇
  1999年   131880篇
  1998年   38345篇
  1997年   33981篇
  1996年   33965篇
  1995年   32494篇
  1994年   30203篇
  1993年   28512篇
  1992年   105525篇
  1991年   103174篇
  1990年   100779篇
  1989年   97394篇
  1988年   90174篇
  1987年   88531篇
  1986年   83708篇
  1985年   80630篇
  1984年   60450篇
  1983年   51848篇
  1982年   30777篇
  1981年   27748篇
  1979年   56807篇
  1978年   40224篇
  1977年   33745篇
  1976年   32150篇
  1975年   34381篇
  1974年   41605篇
  1973年   39793篇
  1972年   37137篇
  1971年   35077篇
  1970年   32348篇
  1969年   30734篇
  1968年   28108篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
目的:探讨福赛类杆菌与人类唾液富脯蛋白相互作用的蛋白分子。方法:Western—blot方法。将人工合成唾液富脯蛋白用生物素标记,福赛类杆菌全菌蛋白凝胶电泳,半干转移至纤维膜上,观察二者的相互作用。结果:富脯蛋白能与分子量为85KD、65KD、60KD、以及49KD的福赛类杆菌蛋白发生结合。结论:福赛类杆菌存在与人类唾液富脯蛋白相互结合的粘附素。  相似文献   
52.
53.
Neurons and related cell types often contain two major classes of neurosecretory vesicles, synaptic vesicles (SVs) and dense-core granules (DCGs), which store and release distinct cargo. SVs store and release classic neurotransmitters, which facilitate propagation of action potentials across the synaptic cleft, whereas DCGs transport, store, and release hormones, proteins, and neuropeptides, which facilitate neuronal survival, synaptic transmission, and learning. Over the past few years, there has been a major surge in our understanding of many of the key molecular mechanisms underlying cargo release from SVs and DCGs. This surge has been driven largely by the use of fluorescence microscopy (especially total internal reflection fluorescence microscopy) to visualize SVs or DCGs in living cells. This review highlights some of the recent insights into cargo release from neurosecretory vesicles provided by fluorescence microscopy, with emphasis on DCGs.  相似文献   
54.
55.
AIM: Cardiovascular risk factors can be present in children and young adults. We previously found abnormal microvascular function in children who had glucose intolerance and insulin resistance. The aim of the present study was to investigate whether they also have abnormalities in left ventricular mass (LVM) and arterial stiffness. METHODS: We measured heart dimensions and LVM using echocardiography, and arterial stiffness using pulse wave analysis in 23 children with good glucose handling (postfeeding glucose: 3.9 to 5 mmol/L) and 21 with poor glucose handling (7.7 to 11.4 mmol/L). RESULTS: The time to pulse reflection was slightly shorter in the poorer glucose handlers (mean+/-SD: 143+/-10 vs 153+/-20 ms, P=0.04), suggestive of increased arterial stiffness. Also in this group, there were significant relationships between intraventricular septal thickness, blood pressure and body mass index, but not in the normal glucose handlers. CONCLUSIONS: We have found that normal children who are in the lowest quintile of glucose tolerance in comparison with their peers are exhibiting the first signs of arterial stiffening. In addition, we have seen the beginnings of a relationship between blood pressure, body mass index and left ventricular enlargement in this group. While these changes may not yet be clinically significant, their emergence might be further evidence of early predisposition to cardiovascular disease.  相似文献   
56.
AIM: To evaluate whether the introduction of a strict protocol approach based on the systemic evaluation of critically ill pregnant women with complications of abortion affected outcome. SETTING: Indigent South Africans managed in the regional and tertiary hospitals of the Pretoria Academic Complex. METHOD: Since 1997 a standard definition of severe acute maternal morbidity (SAMM) has been used in the Pretoria Academic Complex. All cases of SAMM and maternal deaths were entered on the Maternal Morbidity and Mortality Audit System programme. A comparison of outcome of severely ill women who had complications of abortion was made between 1997-1998 (original protocol) and 2002-2004 (strict protocol). OUTCOME MEASURES: The mortality index and prevalence of organ system failure or dysfunction. RESULTS: In 1997-1998 there were 43 women with SAMM who survived and a further 10 maternal deaths due to complications of abortion, compared with 107 women with SAMM and 7 maternal deaths during 2002-2004. The mortality index declined from 18.9% in 1997-1998 to 6.1% in 2002-2004 (p = 0.02, odds ratio 0.28, 95% confidence limits 0.10 - 0.79). Significantly more women had hypovolaemic shock in 2002-2004 compared with 1997-1998 (54.4% v. 35.8%, p = 0.04), but fewer women had immune system failure including septic shock (18.4% v. 47.2%, p = 0.0002) and metabolic dysfunction (0 v. 5.7%, p = 0.03) and there was a trend to less renal failure (10.5% v. 22.6%, p = 0.06) and cardiac failure (4.4% v. 13.2%, p = 0.08). CONCLUSION: The strict protocol approach based on systemic evaluation in managing critically ill pregnant women with complications of abortion, coupled with an intensive, regular feedback mechanism, has been associated with a reduction in the mortality index.  相似文献   
57.
58.
59.
OBJECTIVES: The aim of this study is to evaluate the effect of ZnSO(4) addition to a conventional glass ionomer and a resin-modified glass ionomer on solubility, flexural strength, zinc and fluoride (F) release, and Streptococcus mutans growth inhibition. METHODS: 5 or 10% ZnSO(4) was added to Vitremer and Ketac-Fil powders. Solubility test was performed based on ISO 7489. Flexural strength was determined by 3-point bending test based on ISO 4049. Zn release/uptake was determined by atomic emission spectrometry; F release/uptake was measured using a F-specific electrode. Both release measurements were performed for 15 d before and 15 d after recharging. Antibacterial test was conducted according to agar plate methods against S. mutans, by measuring the inhibition halos in 1-h and 15-d specimens. Data were analyzed by ANOVA. RESULTS: Solubility increased with higher ZnSO(4) content, but remained below the ISO 7489 limit. Flexural strength was not affected by ZnSO(4) addition, and Vitremer performed better than Ketac-Fil. The control materials released no zinc. Vitremer with 10% ZnSO(4) released the highest amount of zinc. Fluoride release was similar for Ketac-Fil and Vitremer. In both cases, the highest amounts were released in the first 24 h. The growth inhibition halo of S. mutans was similar for both materials with highest content of ZnSO(4) and occurred only with 1-h specimens. SIGNIFICANCE: Zinc addition decreased microorganisms growth and improved fluoride release, without significantly affecting the materials' flexural strength and solubility.  相似文献   
60.
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