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   8520篇
  免费   522篇
  国内免费   20篇
耳鼻咽喉   63篇
儿科学   236篇
妇产科学   199篇
基础医学   1339篇
口腔科学   483篇
临床医学   977篇
内科学   1494篇
皮肤病学   153篇
神经病学   769篇
特种医学   211篇
外国民族医学   2篇
外科学   1001篇
综合类   56篇
一般理论   3篇
预防医学   740篇
眼科学   87篇
药学   686篇
中国医学   23篇
肿瘤学   540篇
  2022年   72篇
  2021年   121篇
  2020年   94篇
  2019年   142篇
  2018年   149篇
  2017年   129篇
  2016年   126篇
  2015年   115篇
  2014年   195篇
  2013年   319篇
  2012年   404篇
  2011年   419篇
  2010年   221篇
  2009年   225篇
  2008年   381篇
  2007年   334篇
  2006年   361篇
  2005年   360篇
  2004年   313篇
  2003年   262篇
  2002年   287篇
  2001年   246篇
  2000年   273篇
  1999年   255篇
  1998年   84篇
  1997年   89篇
  1996年   62篇
  1995年   79篇
  1994年   63篇
  1993年   66篇
  1992年   183篇
  1991年   203篇
  1990年   189篇
  1989年   177篇
  1988年   181篇
  1987年   188篇
  1986年   182篇
  1985年   175篇
  1984年   105篇
  1983年   117篇
  1982年   76篇
  1981年   75篇
  1980年   60篇
  1979年   106篇
  1978年   90篇
  1977年   81篇
  1976年   56篇
  1975年   60篇
  1974年   59篇
  1973年   53篇
排序方式: 共有9062条查询结果,搜索用时 15 毫秒
101.
102.
103.
104.
105.
The DNA content of single villous cell nuclei in 14 normal pregnancies and 21 androgenetic moles with a 46,XX karyotype was measured by flow cytometry. Six molar specimens showed a low mean DNA content close to that of normal villi, whereas, 15 specimens were characterized by a high mean DNA content due to a large fraction of nuclei in the triploid to tetraploid region. The latter group presumably corresponds to the previously described "type II" moles in which the DNA pattern resembled the pattern seen in invasive moles and choriocarcinoma.  相似文献   
106.
The use of the original haemolytic plaque reduction technique to measure cytotoxic T lymphocytes (CTL) has been developed further as a rapid screening assay, particularly suitable for limiting dilution analyses. Using hybridoma cells as targets, the cytotoxicity has been measured by the loss of haemolytic plaque formation and by the reduction of the amount of haemolytic monoclonal antibody secreted from viable target cells into the assay supernatants. The assessment of large numbers of cytotoxic samples has been greatly facilitated by quantitating the amount of haemoglobin released in the assay with an automated microELISA multiscanner and by scoring visually using a modification of the spot test. Using these new techniques, relatively high frequency estimates of cytotoxic cell precursors in an allogeneic response (1 in 462 spleen cells) and an anti-fluorescein response (1 in 3970 spleen cells) were obtained.  相似文献   
107.
With reference to a recent taxonomic revision the species of the echinostomes used in key studies on the population regulation in infections with 37-collar-spined Echinostoma species in experimental rodent hosts were reconsidered. This was considered essential to prevent taxonomic problems blocking further fruitful progress within this field of experimental parasitology.  相似文献   
108.
Age-related plasma noradrenaline and neuropeptide Y were evaluated in seven young (mean +/- SD, 28 +/- 3 years) and seven elderly (64 +/- 8 years) normal subjects during rest and different work loads on a cycle ergometer. In the supine and the sitting position plasma noradrenaline and neuropeptide Y were almost identical in the two groups. Plasma neuropeptide Y did not increase during exercise at 100 W for 15 min. At this load plasma noradrenaline levels were higher in the older subjects (mean +/- SEM, 0.97 +/- 0.12 vs. 0.60 +/- 0.09 ng ml-1). There was a significant correlation between plasma noradrenaline and the relative work load at 100 W (r = 0.794, P = 0.0007). At 75% of maximal work load plasma noradrenaline and neuropeptide Y were higher in the young group (1.84 +/- 0.16 vs. 1.26 +/- 0.13 ng ml-1 (noradrenaline) and 38 +/- 4 vs. 22 +/- 5 pmol l-1 (neuropeptide Y)). In the elderly group plasma neuropeptide Y did not increase during exercise and showed a tendency to fall below basal level 5 min post-exercise. It is concluded, that plasma noradrenaline does not increase more in older subjects during exercise when correcting for the generally lower physical fitness in this group compared to younger subjects, and that plasma neuropeptide Y does not increase during exercise in older subjects, suggesting an age-reduced capacity in this system.  相似文献   
109.
110.
A bioavailability study was performed on ten oophorectomized women in a randomized cross-over design. The absorption of tablets containing 2 mg of micronized oestradiol and 1 mg of micronized oestriol (Estrofem®) was compared to the absorption of the same micronized hormones administered in an aqueous suspension. Serum concentration values of oestradiol, oestriol and oestrone were measured by radioimmunoassay. The data obtained were analyzed both by univariate and multivariate analyses, and neither the serum concentrations at the various sample times, the maximum concentrations, the times for the maximum concentrations, nor the areas under the serum concentration curves disclosed any significant differences between the tablet and suspension administrations at the 5% level. The serum concentration values achieved by giving 2 mg of oestradiol and 1 mg of oestriol were of the same magnitude or higher than those of the normal menstrual cycle.  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