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   7176篇
  免费   808篇
  国内免费   4篇
耳鼻咽喉   27篇
儿科学   254篇
妇产科学   172篇
基础医学   1121篇
口腔科学   84篇
临床医学   960篇
内科学   1412篇
皮肤病学   98篇
神经病学   582篇
特种医学   350篇
外科学   884篇
综合类   148篇
一般理论   10篇
预防医学   787篇
眼科学   164篇
药学   521篇
中国医学   2篇
肿瘤学   412篇
  2021年   88篇
  2020年   60篇
  2019年   103篇
  2018年   115篇
  2017年   95篇
  2016年   113篇
  2015年   105篇
  2014年   152篇
  2013年   216篇
  2012年   343篇
  2011年   330篇
  2010年   198篇
  2009年   159篇
  2008年   340篇
  2007年   372篇
  2006年   350篇
  2005年   319篇
  2004年   304篇
  2003年   269篇
  2002年   242篇
  2001年   238篇
  2000年   233篇
  1999年   209篇
  1998年   98篇
  1997年   75篇
  1996年   78篇
  1995年   63篇
  1994年   75篇
  1993年   47篇
  1992年   181篇
  1991年   173篇
  1990年   173篇
  1989年   169篇
  1988年   140篇
  1987年   144篇
  1986年   143篇
  1985年   143篇
  1984年   64篇
  1983年   96篇
  1982年   54篇
  1981年   51篇
  1980年   65篇
  1979年   82篇
  1978年   53篇
  1977年   62篇
  1976年   71篇
  1975年   69篇
  1974年   70篇
  1973年   79篇
  1972年   59篇
排序方式: 共有7988条查询结果,搜索用时 15 毫秒
21.
22.
作者报道2例确诊的慢性丙肝病毒感染患者合并获得性大疱性表皮松解症(EBA)。两例患者临床上均表现为典型EBA,包括皮肤脆性增加及自发和继发于外伤后发生皮肤水疱,继而以粟丘疹和瘢痕愈合。EBA常常是一种免疫状态改变或低下的疾病。还需进一步研究在这两例患者中和一般情况下丙肝病毒是否诱发EBA。  相似文献   
23.
The aim of the present study was to determine whether patients with bronchiectasis and nontuberculous mycobacteria (NTM) have a higher prevalence of Aspergillus-related lung disease. A series of 30 consecutive patients with bronchiectasis and NTM (cases) were compared with 61 patients with bronchiectasis and no evidence of NTM (controls). Aspergillus serology and computerised tomography of the thorax were used to identify Aspergillus-related lung diseases, including aspergilloma, allergic bronchopulmonary aspergillosis and chronic necrotising pulmonary aspergillosis. The rate of positive Aspergillus serology was higher in cases with NTM disease compared with controls (10 out of 30 versus six out of 61). The radiological features of Aspergillus-related lung disease were also more common among patients with NTM disease than controls (six out of 30 versus none out of 61). This association between NTM disease and Aspergillus-related lung disease remained significant after adjustment for confounding effects of age and lung function (adjusted odds ratio 5.1, 95% confidence interval 1.5-17.0). Patients with bronchiectasis and nontuberculous mycobacterial disease have a higher prevalence of coexisting Aspergillus-related lung disease than patients with bronchiectasis and without nontuberculous mycobacteria. Identification of Aspergillus-related lung disease is important as prognosis amongst undetected cases is invariably poor.  相似文献   
24.

Background  

Many factors impacting cecal intubation rates have been examined in detail; however, little information exists regarding the effect of the timing of the procedure. We sought to examine any difference in cecal intubation rates between morning and afternoon colonoscopies and identify factors contributing to a discrepancy.  相似文献   
25.
26.
An open, randomized comparative clinical trial was performed in 153 patients suffering from symptomatic vaginal candidiasis confirmed by mycological tests. Patients were allocated at random into two groups: the first group (consisting of 75 subjects) was treated with a single vaginal ovule of fenticonazole (600 mg) and the second group (consisting of 78 subjects) was treated with a single vaginal tablet of clotrimazole (500 mg). Therapeutic efficacy was assessed by microbiological and clinical criteria 7 days and 1 month (when possible) after the single dose treatment. At the first follow-up visit, complete disappearance of the signs and symptoms or a highly significant reduction of their intensity was observed in both treatment groups. No significant difference was evident between the two drugs. At 7 days, the mycological tests gave negative results in 92% of the patients in the fenticonazole group and in 88.5% of the patients in the clotrimazole group. The difference between the two treatment groups was again not statistically significant. The second follow-up visit was performed in 55 (73.3%) patients of the fenticonazole group and in 52 (66.7%) patients of the clotrimazole group. The results indicate that 83.6% of patients in the fenticonazole group and 69.2% of patients in the clotrimazole group were still disease free at the time of this visit. Both drugs were well tolerated. Mild, local and short lasting side-effects were reported in only 5 cases of the group treated with fenticonazole.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   
27.
Immunohistochemical expression of carbonic anhydrase isoenzyme II (CAII) was demonstrated in a population of fibrous astrocytes in a young lamb and an adult sheep. Such cells were identified by co-expression of CAII and glial fibrillary acidic protein, nuclear morphology and their contribution of glial fibrillary acidic protein reactive processes to the glial limitans. Similar cells were not identified in neonatal lambs. As in man and mouse, CAII was also expressed in choroid plexus epithelium occurring in neonate, young and adult sheep brain. In contrast, however, to man and mouse, CAII was not expressed in sheep oligodendrocytes.  相似文献   
28.
Right-handed B and left-handed Z conformations coexist in equilibrium in portions of plasmids in Escherichia coli. The equilibria are influenced by the length of the sequences that undergo the structural transitions and are perturbed by biological processes. The composite results of three types of determinations indicate a supercoil density of -0.025 in vivo. The coexistence of alternative DNA conformations in living cells implies the potential of these structures or their transitions for important functions in genetic regulatory processes.  相似文献   
29.
30.
Defining the minimum clinically important difference or delta to be detected in a clinical trial depends on a number of factors including the research hypothesis, patient characteristics, the nature of the intervention and the trial design. In 2 previous studies, we have developed standardized procedures for conducting outcome measurement based on current Food and Drug Administration and European League Against Rheumatism guidelines for clinical trials in ankylosing spondylitis, and thereafter, determined the standard deviation for these outcome measures. In the final component of this series of studies, we have employed a Delphi technique to establish estimates for delta, and calculated the sample size requirements under 2 different conditions of Type I and Type II error probabilities.  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