全文获取类型
收费全文 | 4327篇 |
免费 | 461篇 |
国内免费 | 52篇 |
专业分类
耳鼻咽喉 | 43篇 |
儿科学 | 193篇 |
妇产科学 | 68篇 |
基础医学 | 505篇 |
口腔科学 | 63篇 |
临床医学 | 508篇 |
内科学 | 1007篇 |
皮肤病学 | 150篇 |
神经病学 | 423篇 |
特种医学 | 372篇 |
外科学 | 544篇 |
综合类 | 124篇 |
预防医学 | 210篇 |
眼科学 | 98篇 |
药学 | 290篇 |
中国医学 | 19篇 |
肿瘤学 | 223篇 |
出版年
2023年 | 67篇 |
2022年 | 33篇 |
2021年 | 101篇 |
2020年 | 117篇 |
2019年 | 75篇 |
2018年 | 166篇 |
2017年 | 115篇 |
2016年 | 134篇 |
2015年 | 126篇 |
2014年 | 168篇 |
2013年 | 212篇 |
2012年 | 201篇 |
2011年 | 220篇 |
2010年 | 189篇 |
2009年 | 171篇 |
2008年 | 157篇 |
2007年 | 163篇 |
2006年 | 159篇 |
2005年 | 117篇 |
2004年 | 107篇 |
2003年 | 85篇 |
2002年 | 88篇 |
2001年 | 87篇 |
2000年 | 94篇 |
1999年 | 93篇 |
1998年 | 102篇 |
1997年 | 105篇 |
1996年 | 91篇 |
1995年 | 86篇 |
1994年 | 64篇 |
1993年 | 60篇 |
1992年 | 65篇 |
1991年 | 52篇 |
1990年 | 69篇 |
1989年 | 97篇 |
1988年 | 74篇 |
1987年 | 66篇 |
1986年 | 57篇 |
1985年 | 57篇 |
1984年 | 47篇 |
1983年 | 36篇 |
1982年 | 32篇 |
1981年 | 31篇 |
1980年 | 39篇 |
1979年 | 37篇 |
1978年 | 23篇 |
1977年 | 29篇 |
1976年 | 22篇 |
1975年 | 19篇 |
1973年 | 16篇 |
排序方式: 共有4840条查询结果,搜索用时 15 毫秒
1.
2.
3.
4.
5.
6.
Evaluation of polymerase chain reaction and adenosine deaminase assay for the diagnosis of tuberculous effusions in children. 总被引:2,自引:0,他引:2
AIM: To evaluate and compare the utility of polymerase chain reaction (PCR) for the diagnosis of tuberculous effusions in children. METHODS: PCR, adenosine deaminase (ADA) activity and absolute lymphocyte count (ALC) were evaluated in the fluid of 31 tuberculous (20 pleural, 8 ascites and 3 pericardial) and 24 non-tuberculous (10 transudtative ascites, 8 empyema thoracis, 3 malignant pleural and 3 pyopericardium) effusions. RESULTS: Fluid PCR for Mycobacterium tuberculosis was positive in 74% of tuberculous effusions, whereas it was falsely positive in 13% of the non-tuberculous group. The mean fluid ADA and ALC values were significantly higher in tuberculous effusions than in non-tuberculous effusions (p<0.001). The sensitivity and specificity of PCR, ADA (> or =38 IU/l) and ALC (> or =275/mm3) were 74% and 88%, 81% and 75%, and 90% and 83%, respectively, in diagnosing tuberculous effusions. The sensitivity of PCR, ADA and ALC was 100%, 100% and 88%, respectively, for confirmed tuberculous effusions. When the two tests were combined (either/or positive), the sensitivity increased (90-100%) at the expense of specificity. When both the tests were positive, then the specificity markedly increased (92-96%), but sensitivity of the tests decreased. CONCLUSION: Fluid PCR alone should not be relied on as a single test; rather, combined analysis with either ADA or ALC could be more useful in the diagnosis of tuberculous effusions in children. 相似文献
7.
8.
9.
I(indigenous)-compounds are age-related, carcinogen adduct-like, putative indigenous DNA modifications detectable by 32P-postlabeling assay in untreated animals. To investigate the origins of these DNA derivatives, we examined the effects of dietary vitamin E, a natural antioxidant, on I-compounds of rat liver and kidney DNA. Weanling female Sprague-Dawley rats were fed Draper's diets containing 0, 100, 1000, or 10,000 mg/kg alpha-tocopheryl acetate for 6 mo. The DNA from four individual rats of each group was analyzed by a nuclease P1-enhanced version of the 32P-postlabeling assay for DNA adducts. The amount of vitamin E in the liver was measured by high performance liquid chromatography. Rats fed vitamin E-deficient diet (0 mg/kg) showed identical profiles and similar levels of I-compounds as those fed the 100 mg/kg diet. Most I-spots were significantly intensified and one tissue-specific extra spot was found in both liver and kidney DNA of rats fed the 1000 or 10,000 mg/kg vitamin E diet. However, one of the five major I-spots detected in the kidney was weaker in the 1000 and 10,000 mg/kg groups than in the 0 and 100 mg/kg groups. These results show that formation of most I-compounds was not affected by vitamin E-deficient diet, and that long-term feeding of diet containing high levels of vitamin E may cause metabolic alterations leading to an increased formation of DNA-reactive (potentially mutagenic or carcinogenic) electrophiles. 相似文献
10.