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   3377篇
  免费   218篇
  国内免费   11篇
耳鼻咽喉   14篇
儿科学   69篇
妇产科学   128篇
基础医学   413篇
口腔科学   90篇
临床医学   219篇
内科学   712篇
皮肤病学   220篇
神经病学   239篇
特种医学   198篇
外科学   579篇
综合类   31篇
预防医学   150篇
眼科学   49篇
药学   143篇
中国医学   1篇
肿瘤学   351篇
  2022年   34篇
  2021年   57篇
  2020年   41篇
  2019年   77篇
  2018年   93篇
  2017年   64篇
  2016年   74篇
  2015年   94篇
  2014年   109篇
  2013年   172篇
  2012年   177篇
  2011年   191篇
  2010年   100篇
  2009年   81篇
  2008年   155篇
  2007年   146篇
  2006年   123篇
  2005年   150篇
  2004年   117篇
  2003年   111篇
  2002年   112篇
  2001年   62篇
  2000年   96篇
  1999年   85篇
  1998年   30篇
  1997年   41篇
  1996年   31篇
  1995年   38篇
  1994年   35篇
  1993年   27篇
  1992年   81篇
  1991年   64篇
  1990年   71篇
  1989年   73篇
  1988年   57篇
  1987年   48篇
  1986年   47篇
  1985年   47篇
  1984年   35篇
  1983年   25篇
  1979年   19篇
  1978年   21篇
  1977年   24篇
  1976年   25篇
  1975年   28篇
  1974年   18篇
  1973年   28篇
  1972年   19篇
  1971年   22篇
  1970年   20篇
排序方式: 共有3606条查询结果,搜索用时 15 毫秒
71.
72.
73.
Gorlin–Goltz (GS) syndrome is an autosomal dominant disease linked to a mutation in the PTCH gene. Major criteria include the onset of multiple basal cell carcinoma (BCC), keratocystic odontogenic tumours in the jaws and bifid ribs. Dermoscopy and reflectance confocal microscopy represent imaging tools that are able to increase the diagnostic accuracy of skin cancer in a totally noninvasive manner, without performing punch biopsies. Here we present a case of a young woman in whom the combined approach of dermoscopy and RCM led to the identification of multiple small inconspicuous lesions as BCC and thus to the diagnosis of GS syndrome.  相似文献   
74.
75.
Mouse bone marrow cells cultured with human breast cancer MCF-7 cell-conditioned media showed osteoclastogenesis with an increment of bone resorption, although conditioned media from an adriamycin-selected MCF-7 clone (MCF-7ADR) had no effect. Consistently, MCF-7 cells induced 5-fold more in vivo experimental osteolytic bone metastases, with no soft tissue lesions, compared to MCF-7ADR cells. Paracrine factors stimulating (interleukin (IL)-6, IL-1beta, tumor necrosis factor-alpha (TNF-alpha)) or inhibiting (IL-12, IL-18, granulocyte macrophage-colony stimulating factor (GM-CSF)) osteoclastogenesis were significantly increased in MCF-7ADR relative to MCF-7 cells, suggesting that the inhibitory cytokines could selectively overwhelm the effects of the stimulatory ones. Treatment of osteoblast primary cultures with MCF-7-conditioned medium induced a selective upregulation of IL-6 expression, suggesting an indirect stimulation of osteoclastogenesis via the osteoblasts. MCF-7 and MCF-7ADR showed no difference in proliferation rate. However, a higher ability to migrate and invade gelatin and matrigel was observed in MCF-7ADR. Enhanced invasiveness might result from increased metalloproteinase (MMP) activity and cytoskeleton rearrangement. MCF-7ADR cells expressed higher levels of c-Src, focal adhesion kinase (FAK), and protein tyrosine kinase 2 (PYK2) involved in cell adhesion and motility. MCF-7 and MCF-7ADR expressed high and faint levels of functional estrogen receptor alpha (ERalpha), respectively. MCF-7ADR also showed significantly higher levels of the protein kinase C (PKC) alpha and beta2 and a selective activation of PKC compared to MCF-7, where the most abundant isoforms were beta1 and delta. Heat shock protein 27 (Hsp27) was more abundant in MCF-7 cells, but failed to translocate to the nucleus in response to heat shock. In conclusion, we have demonstrated that despite the fact that MCF-7ADR cells showed a more invasive phenotype relative to MCF-7, they have low potential to induce osteolytic bone lesions and stimulate osteoclastogenesis and osteoclast activity. Therefore, we believe that reduced aggressiveness of breast carcinomas could correlate with a greater osteolytic activity featuring their bone metastases.  相似文献   
76.
Zusammenfassung In dieser Arbeit wurden die Gebisse von 31 männlichen und 45 weiblichen Dysgnathieträgern mit Hilfe des Berliner Meßsystems vermessen und die Ergebnisse mit Hilfe eines Computers ausgewertet. Es erfolgt der Vergleich der Parameter zwischen Probanden mit Progenie, Kreuzbiß, offenem Biß und Schmalkiefer. Die Veränderung der Werte wurden longitudinal in den Hauptentwicklungsstufen Milchgebiß, Wechselgebiß und im bleibenden Gebiß untersucht. Dabei werden auch nach der Behandlung noch zwischen den Anomaliegruppen bei einzelnen Werten signifikante Unterschiede gefunden.
Summary In this study dental plaster casts of 31 male and 45 female subjects were measured using the Berlin measurement system and evaluated with the aid of a computer. The parameters of subjects with class III malocclusion, crossbite, open bite and class II/1 malocclusion were compared. The changes were studied longitudinally in the main developmental stages, namely the deciduous, mixed and permanent dentitions. Significant differences were found also following treatment between the malocclusion groups.

Résumé On a mesuré les dentures de 31 hommes et 45 femmes présentant des dysgnathies à l'aide du système de mesure mis au point à Berlin; les valeurs ainsi établies on fait l'objet d'un traitement sur ordinateur. On a procédé à la comparaison des paramètres des sujets atteints de prognathie inférieure, occlusion croisée, béance et endognathie. On a étudié la modification des valeurs de manière longitudinale, en suivant les principales étapes d'évolution: denture lactéale, denture mixte et denture permanente. L'examen a permis, même après le traitement, d'établir, pour chacune des valeurs, des différences importantes d'un groupe d'anomalie à l'autre.
  相似文献   
77.
Antimony telluride (Sb2Te3) thin films were prepared by a room temperature Metal–Organic Chemical Vapor Deposition (MOCVD) process using antimony chloride (SbCl3) and bis(trimethylsilyl)telluride (Te(SiMe3)2) as precursors. Pre-growth and post-growth treatments were found to be pivotal in favoring out-of-plane and in-plane alignment of the crystallites composing the films. A comprehensive suite of characterization techniques were used to evaluate their composition, surface roughness, as well as to assess their morphology, crystallinity, and structural features, revealing that a quick post-growth annealing triggers the formation of epitaxial-quality Sb2Te3 films on Si(111).

Highly oriented antimony telluride thin films are prepared by room temperature metalorganic chemical vapor deposition on Si(111).  相似文献   
78.
Pigmented facial macules are common on sun damage skin. The diagnosis of early stage lentigo maligna (LM) and lentigo maligna melanoma (LMM) is challenging. Reflectance confocal microscopy (RCM) has been proven to increase diagnostic accuracy of facial lesions. A total of 154 pigmented facial macules, retrospectively collected, were evaluated for the presence of already‐described RCM features and new parameters depicting aspects of the follicle. Melanocytic nests, roundish pagetoid cells, follicular infiltration, bulgings from the follicles and many bright dendrites and infiltration of the hair follicle (ie, folliculotropism) were found to be indicative of LM/LMM compared to non‐melanocytic skin neoplasms (NMSNs), with an overall sensitivity of 96% and specificity of 83%. Concerning NMSNs, solar lentigo and lichen planus‐like keratosis resulted better distinguishable from LM/LMM because usually lacking malignant features and presenting characteristic diagnostic parameters, such as epidermal cobblestone pattern and polycyclic papillary contours. On the other hand, distinction of pigmented actinic keratosis (PAK) resulted more difficult, and needing evaluation of hair follicle infiltration and bulging structures, due to the frequent observation of few bright dendrites in the epidermis, but predominantly not infiltrating the hair follicle (estimated specificity for PAK 53%). A detailed evaluation of the components of the folliculotropism may help to improve the diagnostic accuracy. The classification of the type, distribution and amount of cells, and the presence of bulging around the follicles seem to represent important tools for the differentiation between PAK and LM/LMM at RCM analysis.  相似文献   
79.
80.
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