收费全文 | 16166篇 |
免费 | 1760篇 |
国内免费 | 30篇 |
耳鼻咽喉 | 133篇 |
儿科学 | 347篇 |
妇产科学 | 355篇 |
基础医学 | 2456篇 |
口腔科学 | 298篇 |
临床医学 | 1548篇 |
内科学 | 2998篇 |
皮肤病学 | 233篇 |
神经病学 | 1544篇 |
特种医学 | 606篇 |
外科学 | 2468篇 |
综合类 | 538篇 |
一般理论 | 56篇 |
预防医学 | 1723篇 |
眼科学 | 496篇 |
药学 | 1207篇 |
中国医学 | 8篇 |
肿瘤学 | 942篇 |
2022年 | 155篇 |
2021年 | 342篇 |
2020年 | 200篇 |
2019年 | 326篇 |
2018年 | 358篇 |
2017年 | 253篇 |
2016年 | 238篇 |
2015年 | 333篇 |
2014年 | 426篇 |
2013年 | 582篇 |
2012年 | 773篇 |
2011年 | 841篇 |
2010年 | 447篇 |
2009年 | 385篇 |
2008年 | 725篇 |
2007年 | 709篇 |
2006年 | 589篇 |
2005年 | 621篇 |
2004年 | 627篇 |
2003年 | 561篇 |
2002年 | 555篇 |
2001年 | 503篇 |
2000年 | 502篇 |
1999年 | 475篇 |
1998年 | 196篇 |
1997年 | 179篇 |
1996年 | 169篇 |
1995年 | 175篇 |
1994年 | 160篇 |
1993年 | 142篇 |
1992年 | 357篇 |
1991年 | 366篇 |
1990年 | 342篇 |
1989年 | 372篇 |
1988年 | 292篇 |
1987年 | 310篇 |
1986年 | 299篇 |
1985年 | 345篇 |
1984年 | 259篇 |
1983年 | 211篇 |
1982年 | 117篇 |
1980年 | 112篇 |
1979年 | 191篇 |
1978年 | 133篇 |
1977年 | 107篇 |
1975年 | 116篇 |
1974年 | 129篇 |
1973年 | 121篇 |
1972年 | 131篇 |
1971年 | 110篇 |
Objectives We sought to assess the presence of betaPV in NMSC biopsies from a group of Scottish skin cancer patients, both immunocompetent (IC) patients and immunosuppressed (IS) organ transplant recipients.
Methods One hundred and twenty-one paraffin-embedded skin tumours (27 actinic keratosis, 41 intraepidermal carcinoma, 53 squamous cell carcinoma) and 11 normal skin samples were analysed for the presence of betaPV by a polymerase chain reaction–reverse hybridization assay designed to detect the presence of the 25 known betaPV genotypes.
Results In IC patients, betaPV was detected in 30 of 59 (51%) tumours and two of 11 (18%) normal skin samples ( P = 0·046). In IS patients, betaPV was found in 27 of 62 (44%) tumours; no normal skin samples were available for comparison. The most frequently found genotypes were HPV-24, HPV-15 and HPV-38. Of those tumours infected with betaPV, 28 of 57 (49%) were infected with more than one genotype (range 2–8). Tumours from IS patients were from a younger age group (mean age 57·4 years) than IC patients (mean age 73·8 years). Multiple infections were more common in tumours from IC patients (21 of 30; 70%) compared with those from IS patients (seven of 27; 26%) ( P < 0·001). In the IC group, age did not appear to influence the distribution of single and multiple infections whereas in IS patients the proportion of multiple infections to single infections increased with age. There were no multiple infections in normal skin.
Conclusions A wide spectrum of betaPV types was detected in our samples. Further characterization of betaPV in vivo is needed in order to determine the mechanisms by which the virus contributes to cutaneous carcinogenesis. 相似文献
Methods: Ten volunteers breathed 500 ppm carbon monoxide until their carboxyhemoglobin levels reached 15%, and 10 different volunteers received intravenous sodium nitrite, 300 mg, to induce methemoglobin. All were instrumented with arterial cannulas and six Masimo Rad-57 (Masimo Inc., Irvine, CA) pulse oximeter sensors. Arterial blood was analyzed by three laboratory CO-oximeters, and the resulting carboxyhemoglobin and methemoglobin measurements were compared with the corresponding pulse oximeter readings.
Results: The Rad-57 measured carboxyhemoglobin with an uncertainty of +/-2% within the range of 0-15%, and it measured methemoglobin with an uncertainty of 0.5% within the range of 0-12%. 相似文献