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   8975篇
  免费   555篇
  国内免费   157篇
耳鼻咽喉   120篇
儿科学   152篇
妇产科学   104篇
基础医学   1316篇
口腔科学   181篇
临床医学   761篇
内科学   1867篇
皮肤病学   192篇
神经病学   583篇
特种医学   611篇
外国民族医学   2篇
外科学   1291篇
综合类   170篇
预防医学   591篇
眼科学   232篇
药学   756篇
  1篇
中国医学   151篇
肿瘤学   606篇
  2023年   79篇
  2022年   278篇
  2021年   376篇
  2020年   181篇
  2019年   256篇
  2018年   271篇
  2017年   200篇
  2016年   315篇
  2015年   402篇
  2014年   485篇
  2013年   545篇
  2012年   871篇
  2011年   759篇
  2010年   381篇
  2009年   359篇
  2008年   542篇
  2007年   446篇
  2006年   436篇
  2005年   361篇
  2004年   336篇
  2003年   335篇
  2002年   269篇
  2001年   180篇
  2000年   167篇
  1999年   149篇
  1998年   77篇
  1997年   50篇
  1996年   46篇
  1995年   38篇
  1994年   24篇
  1993年   25篇
  1992年   32篇
  1991年   42篇
  1990年   25篇
  1989年   28篇
  1988年   30篇
  1987年   25篇
  1986年   26篇
  1985年   26篇
  1984年   17篇
  1983年   21篇
  1982年   15篇
  1981年   12篇
  1980年   12篇
  1979年   17篇
  1978年   11篇
  1976年   10篇
  1974年   9篇
  1970年   12篇
  1968年   9篇
排序方式: 共有9687条查询结果,搜索用时 0 毫秒
21.
Summary A single oral dose of verapamil 80 mg was shown significantly to inhibit histamine-induced bronchoconstriction in 8 out of 16 asthmatic subjects (maximum increase in PD20FEVHi 416%). There was still significant protection ( PD20FEV1Hi>100%) in the responders 5 h after the oral dose. The relationship of the bronchoprotective effect to the plasma level of verapamil was also examined. Responders and non-responders did not differ significantly in the peak plasma level or the time course of the plasma verapamil concentration.The protective effect was not correlated with the peak plasma level of verapamil or with the baseline bronchial hyperreactivity.  相似文献   
22.
兴山五味子;;襄五脂素;;主要药理作用  相似文献   
23.
In Langerhans' cell histiocytosis, the prognostic significance of pulmonary disease is controversial. The clinical and radiological features and lung function tests of Langerhans' cell histiocytosis patients presenting to a single tertiary referral center between 1981 and 1987 were reviewed. Age at diagnosis ranged from 2 weeks to 16 years (median 1.7 years) and the male-female ratio was 2.4:1. No child presented with lung involvement alone. In 18 (40%) of 45 patients with multisystem disease there was clinical and/or radiological evidence of lung pathology. Another 6 children (13%) with normal chest roentgenograms had abnormal lung function tests, suggesting subclinical ("occult") involvement. Those with overt lung disease tended to present at a younger than average age (median 0.6 years). The most common functional disturbance was reduced lung or respiratory compliance with reduced lung volumes. Patients with and without lung involvement showed a similar pattern of involvement of other organs, with skin and bone most commonly affected. Of the 45 children with multisystem disease, 38 (84%) survived 2 to 7 years after diagnosis; there was a similar proportion of deaths in children with and without lung involvement. It is concluded that lung involvement occurs in nearly half of young children with multisystem Langerhans' cell histiocytosis but does not adversely affect outcome.  相似文献   
24.
1110 neonates, from 30 to 42 of estimated gestational age (EGA) were measured on the 1st day of life to estimate upper mid-arm circumference (MAC) and head circumference (HC). Individual MAC/HC ratio was calculated. MAC/HC ratio was used to estimate gestational age and nutritional status of the newborns. We proved that MAC/HC ratio increased linearly between 30 and 38 week of pregnancy and it stabilized between 38-42 week. We compared MAC/HC ratio with birth weight, skin fold score, and ponderal index. We concluded that this ratio may be very useful to estimate gestational age and to include the neonates to "the group of risk".  相似文献   
25.
Poly(ADP-ribose) polymerase-1 (PARP-1) is a nuclear enzyme, activated by DNA strand breaks to participate in DNA repair. Overactivation of PARP by cellular insults depletes its substrate NAD(+) and then ATP, leading to a major energy deficit and cell death. This mechanism appears to be prominent in vascular stroke and other neurodegenerative processes in which PARP gene deletion and PARP-inhibiting drugs provide major protection. Cell death associated with PARP-1 overactivation appears to be predominantly necrotic while apoptosis is associated with PARP-1 cleavage, which may conserve energy needed for the apoptotic process. Novel forms of PARP derived from distinct genes and lacking classic DNA-binding domains may have nonnuclear functions, perhaps linked to cellular energy dynamics.  相似文献   
26.
27.
28.
Angiogenesis is an essential process in the development, growth, and metastasis of malignant tumors including lung cancer. DNA sequence variations in the vascular endothelial growth factor (VEGF) gene may lead to altered VEGF production and/or activity, thereby causing interindividual differences in the susceptibility to lung cancer via their actions on the pathways of tumor angiogenesis. To test this hypothesis, we investigated the potential association between three VEGF polymorphisms (-460T > C, +405C > G, and 936C > T)/haplotypes and the risk of lung cancer in a Korean population. VEGF genotypes were determined in 432 lung cancer patients and 432 healthy controls that were frequency matched for age and sex. VEGF haplotypes were predicted using Bayesian algorithm in the phase program. Compared with the combined +405 CC and CG genotype, the +405 GG genotype found associated with a significantly decreased risk of small cell carcinoma [SCC; adjusted odds ratio (OR), 0.36; 95% confidence interval (95% CI), 0.17-0.78]. The 936 CT genotype and the combined 936 CT and TT genotype were also associated with a significantly decreased risk of SCC compared with the 936 CC genotype (adjusted OR, 0.47; 95% CI, 0.26-0.85 and adjusted OR, 0.44; 95% CI, 0.24-0.80, respectively). Haplotype CGT was associated with a significantly decreased risk of SCC (adjusted OR, 0.39; 95% CI, 0.18-0.87), whereas haplotype TCC conferred a significantly increased risk of SCC (adjusted OR, 1.63; 95% CI, 1.14-2.33). None of the VEGF polymorphisms studied significantly influenced the susceptibility to lung cancer except SCC. However, haplotypes TCT and TGT were significantly associated with the risk of overall lung cancer, respectively (adjusted OR, 0.38; 95% CI, 0.25-0.60 and adjusted OR, 3.94; 95% CI, 2.00-7.76, respectively). These effects of haplotypes TCT and TGT on lung cancer risk were observed in three major histologic types of lung cancer. These results suggest that the VEGF gene may be contribute to an inherited predisposition to lung cancer.  相似文献   
29.
30.
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