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   1965篇
  免费   109篇
  国内免费   17篇
耳鼻咽喉   17篇
儿科学   80篇
妇产科学   24篇
基础医学   250篇
口腔科学   37篇
临床医学   119篇
内科学   314篇
皮肤病学   18篇
神经病学   161篇
特种医学   159篇
外科学   409篇
综合类   29篇
预防医学   57篇
眼科学   31篇
药学   176篇
中国医学   2篇
肿瘤学   208篇
  2023年   13篇
  2022年   39篇
  2021年   63篇
  2020年   33篇
  2019年   47篇
  2018年   38篇
  2017年   27篇
  2016年   42篇
  2015年   45篇
  2014年   55篇
  2013年   86篇
  2012年   142篇
  2011年   149篇
  2010年   75篇
  2009年   79篇
  2008年   152篇
  2007年   138篇
  2006年   137篇
  2005年   112篇
  2004年   115篇
  2003年   95篇
  2002年   93篇
  2001年   26篇
  2000年   19篇
  1999年   30篇
  1998年   13篇
  1997年   10篇
  1996年   8篇
  1995年   15篇
  1994年   6篇
  1993年   13篇
  1992年   34篇
  1991年   20篇
  1990年   21篇
  1989年   21篇
  1988年   14篇
  1987年   8篇
  1986年   9篇
  1985年   2篇
  1984年   3篇
  1983年   3篇
  1982年   4篇
  1981年   3篇
  1980年   5篇
  1979年   5篇
  1975年   2篇
  1974年   2篇
  1972年   4篇
  1970年   5篇
  1969年   3篇
排序方式: 共有2091条查询结果,搜索用时 19 毫秒
51.
52.
The objective of this study was to compare the morphological and chemical composition of bone graft (BG) and coral graft (CG) as well as their osteogenic differentiation potential using rabbit mesenchymal stem cells (rMSCs) in vitro. SEM analysis of BG and CG revealed that the pores in these grafts were interconnected, and their micro-CT confirmed pore sizes in the range of 107-315 µm and 103-514 µm with a total porosity of 92% and 94%, respectively. EDS analysis indicated that the level of calcium in CG was relatively higher than that in BG. FTIR of BG and CG confirmed the presence of functional groups corresponding to carbonyl, aromatic, alkyl, and alkane groups. XRD results revealed that the phase content of the inorganic layer comprised highly crystalline form of calcium carbonate and carbon. Atomic force microscopy analysis showed CG had better surface roughness compared to BG. In addition, significantly higher levels of osteogenic differentiation markers, namely, alkaline phosphatase (ALP), Osteocalcin (OC) levels, and Osteonectin and Runx2, Integrin gene expression were detected in the CG cultures, when compared with those in the BG cultures. In conclusion, our results demonstrate that the osteogenic differentiation of rMSCs is relatively superior in coral graft than in bone graft culture system.  相似文献   
53.
HbA1c values are heavily relied on to assess glycemic control. Hemoglobin variants may interfere with measurements of HbA1c resulting in falsely low values. We present the first report of a rare variant of Hb in a patient with type 2 diabetes, which lead to a falsely low HbA1c.  相似文献   
54.
Modulation of the cytotoxicity and mutagenicity of 4-hydroxyestradiol (4-OHE(2)), an oxidative metabolite of estrogen, by antioxidants was assessed in human MCF7 cells and TK-6 lymphoblast cells. The cytotoxicity of the catecholic estrogens was potentiated by depletion of intracellular glutathione and was independent of oxygen concentration. Agents such as the nitroxide Tempol can facilitate the oxidation of the semiquinone to the Q and enhanced 4-OHE(2) cytotoxicity. Conversely, reducing agents such as ascorbate, cysteine, and 1,4-dihydroxytetramethylpiperidine (THP) protected against cytotoxicity and decreased mutation induction, presumably by reducing the semiquinone to the hydroquinone. Our results support the proposition that oxidation of the semiquinone to the corresponding Q is crucial in eliciting the deleterious effects of catecholic estrogens. Furthermore, because the deleterious effects of 4-OHE(2) were abrogated by dietary and synthetic antioxidants, our results would support the chemopreventive use of diets rich in reducing substances (vitamins and added synthetic antioxidants) as a means of decreasing the risks associated with estrogen exposure and developing of breast cancer.  相似文献   
55.
BACKGROUND: Although recurrent major depression in elderly individuals is a disabling condition, only a few studies have systematically examined the magnitude and specificity of quality-of-life (QOL) impairments in such patients in comparison with matched controls or the elderly population. METHODS: We examined the variations in QOL scores of 100 elderly (age range 60-88 years) patients with moderate to severe recurrent major depression and compared them with published elderly population norms. Disease-specific Quality of Life in Depression Scale (QLDS) and generic Medical Outcomes Short Form-36 Health Survey (SF-36) QOL ratings obtained at baseline were analyzed. RESULTS: Compared with published elderly population norms, depressed subjects showed significant QOL impairments in five of eight baseline SF-36 items (p <.01). Women rated their QOL as worse than men on physical functioning and role physical (p <.01) and showed similar trends on all other QOL items. Compared with younger subjects, subjects aged older than 70 years reported lower QOL on the summary physical component (p <.01) and a trend for higher QOL on the summary mental component (p <.05) of the SF-36. Depression symptom ratings were correlated with some QOL measures, but accounted for less than 10% of the variance. CONCLUSIONS: Despite limitations, such as a cross-sectional design and indirect comparisons with norms generated from another study, our findings confirm the disabling nature of recurrent late-life depression and the importance of targeting both depressive symptoms and broader QOL outcomes in intervention trials.  相似文献   
56.
57.
This is an overview of radiological imaging of the hand highlighting the various imaging modalities used in the work-up and diagnosis of a range of orthopaedic and rheumatological disorders. The biomechanics and anatomy of the human hand is extremely complex, and a good understanding is required to diagnose pathology. In this article we explain the anatomy and highlight pathology of the hand from a radiological perspective with respect to plain film, CT, ultrasound and MR imaging. Trauma of the hand is extremely common and radiology plays an important role in the diagnosis of treatable injuries including fractures, dislocations and ligament tears. Plain radiography and CT are excellent at evaluating bony injury (e.g. Rolondo or Bennett's fracture) whereas ultrasound and MR are better at evaluating soft tissue injury (e.g. Stener lesion). The hands are a common location for degenerate and inflammatory arthropathies which all have hallmark radiological features. Radiology also plays an important role in the diagnosis and work-up of bone lesions in the hand including enchondromas, osteoid osteomas and chondrosarcomas.  相似文献   
58.
59.
60.
Obstructive apneas produce high negative intrathoracic pressure that imposes an afterload burden on the left ventricle. Such episodes might produce structural changes in the left ventricle over time. Doppler echocardiograms were obtained within 2 months of attended polysomnography. Patients were grouped according to apnea-hypopnea index (AHI): mild/no obstructive sleep apnea (OSA; AHI <15) and moderate/severe OSA (AHI ≥15). Mitral valve tenting height and area, left ventricular (LV) long and short axes, and LV end-diastolic volume were measured in addition to tissue Doppler parameters. Comparisons of measurements at baseline and follow-up between and within groups were obtained; correlations between absolute changes (Δ) in echocardiographic parameters were also performed. After a mean follow-up of 240 days mitral valve tenting height increased significantly (1.17 ± 0.12 to 1.28 ± 0.17 cm, p = 0.001) in moderate/severe OSA as did tenting area (2.30 ± 0.41 to 2.66 ± 0.60 cm(2), p = 0.0002); Δtenting height correlated with ΔLV end-diastolic volume (rho 0.43, p = 0.01) and Δtenting area (rho 0.35, p = 0.04). In patients with mild/no OSA there was no significant change in tenting height; there was a borderline significant increase in tenting area (2.20 ± 0.44 to 2.31 ± 0.43 cm(2), p = 0.05). Septal tissue Doppler early diastolic wave decreased (8.04 ± 2.49 to 7.10 ± 1.83 cm/s, p = 0.005) in subjects with moderate/severe OSA but not in in those with mild/no OSA. In conclusion, in patients with moderate/severe OSA, mitral valve tenting height and tenting area increase significantly over time. This appears to be related, at least in part, to changes in LV geometry.  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