全文获取类型
收费全文 | 121564篇 |
免费 | 11134篇 |
国内免费 | 5138篇 |
专业分类
耳鼻咽喉 | 913篇 |
儿科学 | 4329篇 |
妇产科学 | 3392篇 |
基础医学 | 12108篇 |
口腔科学 | 3268篇 |
临床医学 | 11209篇 |
内科学 | 19100篇 |
皮肤病学 | 1612篇 |
神经病学 | 7709篇 |
特种医学 | 2208篇 |
外国民族医学 | 37篇 |
外科学 | 11699篇 |
综合类 | 19555篇 |
现状与发展 | 21篇 |
一般理论 | 1篇 |
预防医学 | 13925篇 |
眼科学 | 3403篇 |
药学 | 9334篇 |
63篇 | |
中国医学 | 3499篇 |
肿瘤学 | 10451篇 |
出版年
2024年 | 381篇 |
2023年 | 1802篇 |
2022年 | 3813篇 |
2021年 | 5056篇 |
2020年 | 4655篇 |
2019年 | 3739篇 |
2018年 | 3798篇 |
2017年 | 4164篇 |
2016年 | 4571篇 |
2015年 | 4499篇 |
2014年 | 8169篇 |
2013年 | 9343篇 |
2012年 | 7829篇 |
2011年 | 8575篇 |
2010年 | 6947篇 |
2009年 | 6535篇 |
2008年 | 6583篇 |
2007年 | 6599篇 |
2006年 | 5822篇 |
2005年 | 5202篇 |
2004年 | 4290篇 |
2003年 | 3653篇 |
2002年 | 3002篇 |
2001年 | 2593篇 |
2000年 | 2183篇 |
1999年 | 1752篇 |
1998年 | 1547篇 |
1997年 | 1361篇 |
1996年 | 1180篇 |
1995年 | 1025篇 |
1994年 | 943篇 |
1993年 | 782篇 |
1992年 | 706篇 |
1991年 | 629篇 |
1990年 | 539篇 |
1989年 | 459篇 |
1988年 | 356篇 |
1987年 | 308篇 |
1986年 | 293篇 |
1985年 | 397篇 |
1984年 | 325篇 |
1983年 | 218篇 |
1982年 | 268篇 |
1981年 | 198篇 |
1980年 | 153篇 |
1979年 | 119篇 |
1978年 | 103篇 |
1977年 | 83篇 |
1976年 | 92篇 |
1975年 | 55篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
11.
C. M. Gordon E. Binello M. S. LeBoff M. E. Wohl C. J. Rosen A. A. Colin 《Osteoporosis international》2006,17(5):783-790
Introduction Patients with cystic fibrosis (CF) are known to be at risk for early osteoporosis, and the mechanisms that mediate bone loss
are still being delineated. The aim of the present investigation was to investigate if a correlation exists in these patients
between skeletal measurements by dual-energy x-ray absorptiometry (DXA) and two anabolic factors, dehydroepiandrosterone (DHEA)
and insulin-like growth factor I (IGF-I), and proresorptive factors such as the cytokines interleukin-1β, tumor necrosis factor α,
and interleukin-6.
Methods We studied 32 outpatients (18 females; mean age: 26.2 ± 7.9 years) at a tertiary care medical center. The subjects had venous
samples obtained, underwent anthropometric and bone mineral density (BMD) measurements, and completed a health survey. Serum
IGF-I concentrations were below the age-adjusted mean in 78% of the participants, and DHEA sulfate (DHEAS) concentrations
were low in 72%. Serum concentrations of all cytokines were on the low side of normal; nonetheless, there was a modest inverse
correlation between IL-1β and BMD at all sites.
Results In univariate analyses, IGF-I and DHEAS were significant correlates of BMD or bone mineral content. In final multivariate
models controlling for anthropometric and other variables of relevance to bone density, only IGF-I was identified as a significant
independent skeletal predictor. While alterations in DHEAS, IGF-I, and specific cytokines may contribute to skeletal deficits
in patients with CF, of these factors a low IGF-I concentration appears to be most strongly correlated with BMD.
Conclusions These findings may have therapeutic implications for enhancing bone density in these patients. 相似文献
12.
慢性肾衰竭急性加重的临床特征及相关因素分析 总被引:2,自引:0,他引:2
目的:探讨慢性肾衰竭(CRF)急性加重因素及其治疗措施对预后的影响。方法:对2001年1月~2005年6月住院治疗的CRF急性加重患者42例,按其加重原因、基础疾病、治疗方式和疗效进行回顾性总结。结果:CRF急性加重因素依次为各种感染(45.2%)、原发病加重(19.0%)、高血压未控制(14.3%)、水电解质紊乱(11.9%)、肾毒性药物(11.9%)、心功能不全(9.5%)、尿路梗阻(4.8%)、血高粘滞状态(2.4%),7例同时存在≥2种上述病因(16.7%)。CRF急性加重原发病以慢性肾小球肾炎(52.4%)和糖尿病肾病(11.9%)为主。积极治疗后肾功能恢复达到或接近原来水平者40例,死亡2例,死亡2例的年龄均在60岁以上。结论:对于CRF肾功能急剧恶化的患者,应积极寻找其加重因素,并采取非透析和透析相结合治疗,改善肾功能,降低病死率,延长患者生命。 相似文献
13.
Mariela Dutra Gontijo Moura Soraya de Mattos Camargo Grossmann Linaena Méricy da Silva Fonseca Maria Inês Barreiros Senna Ricardo Alves Mesquita 《Journal of oral pathology & medicine》2006,35(6):321-326
BACKGROUND: Oral hairy leukoplakia (OHL) may be an indicator of the progression of Human Immunodeficiency Virus (HIV)-induced immuno-depression, and the evaluation of risk factors leading to OHL is important in the management of these HIV-infected patients. However, there are few studies that analyze risk factors leading to OHL in the Brazilian population. The aim of this case-control study is to present data about prevalence rates and risk factors leading to OHL in a sample of HIV-infected adults in Brazil. METHODS: This case-control study included 111 HIV-infected patients treated at a clinic for sexually transmitted diseases and HIV. In the initial examinations with dentists, variables were collected from all patients. Diagnosis of OHL was performed in accordance with the International Classification System and cytological features. The Fisher and the chi-squared tests were used for statistical analysis. The proportional prevalence and odds ratio were estimated. RESULTS: Outcome presented a positive, statistically significant association among the presence of OHL and viral load of 3000 copies/mul or greater (P = 0.0001; odds ratio (OR) = 5.8), presence of oral candidiasis (P = 0.0000; OR = 11.1), previous use of fluconazole (P = 0.0000; OR = 24.6), and use of systemic acyclovir (P = 0.032; OR = 4.3). Antiretroviral medication presented a negative, statistically significant association with the presence of OHL (P = 0.002; OR = 8.4). CONCLUSIONS: Prevalence of OHL was 28.8%. Viral load, oral candidiasis, previous use of fluconazole, and systemic acyclovir were determined to be risk factors for OHL. Antiretroviral medication proved to be protective against the development of OHL. 相似文献
14.
表皮生长因子对牛眼小梁细胞c—fos基因表达的诱导 总被引:4,自引:0,他引:4
目的研究表皮生长因子(epidermalgrowthfactor,EGF)对小梁细胞的作用。方法应用分子杂交技术研究EGF对体外培养的牛眼小梁细胞c-fos基因表达的诱导和3H胸腺核苷酸(3H-thymidineincorparation,3H-TdR)掺入法观察细胞DNA的合成。结果小梁细胞的3H-TdR掺入率随着EGF浓度不同而变化,浓度为20~150ng/ml时,细胞掺入率随浓度增加升高(P<0.01)。与对照组相比,EGF刺激停止生长的小梁细胞0.5小时后,c-fos基因开始表达,1小时后达高峰,至2小时后消失。不同浓度EGF刺激小梁细胞1小时后,c-fos基因表达呈浓度依赖性。结论实验结果表明EGF刺激小梁细胞增殖或进入生长状态,可能与c-fos基因产物的信号传递作用有关。 相似文献
15.
16.
Acoustic rhinometry was performed in 35 normal nose-breathing children between 3 and 6 years. The average cross-sectional areas at the nasal valve, at the anterior end of the turbinates, and in the nasopharynx were 0.34±0.06 cm2, 0.35±0.08 cm2 and 1.37±0.48 cm2 respectively. The average minimal cross-sectional area was 0.29±0.06 cm2. The minimal cross-sectional area was located at the nasal valve in 14 and at the anterior end of nasal tubinates in 21 of the 35 children. As would be expected, the cross-sectional areas at different sites of the nasal cavity increased with increasing age of the children. But, whereas the minimal cross-sectional area increased by 0.024 cm2 per year, the nasopharyngeal cross-sectional area increased by 0.20 cm2 per year. No significant differences were found between boys and girls. Measurements of the posterior nasal and nasopharyngeal cross-sectional areas were unreliable, whenever the minimal cross-sectional area was less than 0.2 cm2. Furthermore, assessment of the nasopharynx may be difficult because of involuntary movements of the soft palate. 相似文献
17.
T. A. Mustoe M.D. L. B. Kaban J. B. Mulliken 《European journal of plastic surgery》1987,10(4):135-138
Summary A group of thirty children with nasal fractures was evaluated retrospectively by means of a questionnaire and hospital records. Age at the time of injury ranged from age 3 to 12 (mean = 8.6) years and mean follow-up period was 9 years. Eight patients reported some degree of nasal obstruction post reduction, but only one patient required submucous resection and two patients underwent septorhinoplasty for appearance. No patients reported class III malocclusion, or required orthodontic treatment or maxillofacial corrective surgery for maxillary hypoplasia. We concluded that a childhood nasal fracture treated by closed reduction does not have deleterious effects on facial or nasal growth.This work was supported in part by the Brigham Surgical Group Foundation, Inc., Boston, Massachusetts, USA 相似文献
18.
H J Schluesener 《Journal of neuroscience research》1991,28(2):310-314
The transforming growth factors type beta 1, beta 2, and beta 1.2 suppress multidrug transport in human pat-1 glioblastoma cells and even in cells that strongly over-express mdr genes and are resistant to inhibition of multidrug transport by chemosensitizers. Thus, inhibition of multidrug transport by cytokines might be a new approach to increase cellular accumulation of chemotherapeutic agents in multidrug resistant glial tumor cells. Interestingly, a member of the more distantly related decapentaplegic subgroup of transforming growth factors, the bone morphogenetic protein BMP 2, did not inhibit multidrug transport. 相似文献
19.
目的 探讨种植受体血管内皮细胞在抗异种血管移植超急排斥反应 (HAR)方面的意义。方法 选用豚鼠→大鼠移植模型 ,先将分离、培养的大鼠动脉内皮细胞种植于去内皮的豚鼠动脉内壁 ,再将此豚鼠动脉植入大鼠体内 ,观察动脉血栓形成时间 ,并采用免疫组化技术检测了 Ig M、C3在移植后豚鼠动脉壁上沉积的情况。结果 已种植大鼠内皮细胞的豚鼠动脉血栓形成时间 (2 0 .3± 4.42 h)较植入大鼠体内的正常豚鼠动脉 (0 .35± 0 .2 84h)以及单纯去内皮豚鼠动脉血栓形成时间 (0 .16 5± 0 .0 77h)显著延长 (P<0 .0 0 1)。免疫组化结果显示 ,植入大鼠体内的正常豚鼠内皮细胞表面有 Ig M和 C3沉积 ,而预先种植大鼠内皮细胞的豚鼠动脉内壁无 Ig M和 C3沉积。结论 在异种供体血管壁上预先种植受者血管内皮细胞 ,可延长移植的异种供体血管通畅时间 ,该技术可能在抗异种血管移植 HAR方面具有重要意义 相似文献
20.
Xiaoguang Chen Yi Li Lei Wang Mark Katakowski Lijie Zhang Jieli Chen Yongxian Xu Subhash C. Gautam Michael Chopp 《Neuropathology》2002,22(4):275-279
Intravenous administration of human bone marrow stromal cells (hMSCs) after middle cerebral artery occlusion (MCAo) in rats provides functional benefit. We tested the hypothesis that these functional benefits are derived in part from hMSC production of growth and trophic factors. Quantitative sandwich enzyme‐linked immunosorbent assay (ELISA) of hMSCs cultured with normal and MCAo brain extracts were performed. hMSCs cultured in supernatant derived from ischemic brain extracts increased production of brain‐derived neurotrophic factor (BDNF), nerve growth factor (NGF), vascular endothelial growth factor (VEGF) and hepatocyte growth factor (HGF). These neurotrophins and angiogenic growth factors increased in a post‐ischemia time‐dependent manner. The hMSC capacity to increase expression of growth and trophic factors may be the key to the benefit provided by transplanted hMSCs in the ischemic brain. 相似文献