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   10608篇
  免费   760篇
  国内免费   303篇
耳鼻咽喉   151篇
儿科学   67篇
妇产科学   30篇
基础医学   1299篇
口腔科学   97篇
临床医学   565篇
内科学   522篇
皮肤病学   30篇
神经病学   1919篇
特种医学   563篇
外国民族医学   2篇
外科学   2161篇
综合类   837篇
预防医学   146篇
眼科学   2582篇
药学   378篇
  3篇
中国医学   241篇
肿瘤学   78篇
  2024年   32篇
  2023年   187篇
  2022年   337篇
  2021年   452篇
  2020年   392篇
  2019年   351篇
  2018年   396篇
  2017年   362篇
  2016年   360篇
  2015年   368篇
  2014年   667篇
  2013年   808篇
  2012年   465篇
  2011年   511篇
  2010年   420篇
  2009年   447篇
  2008年   507篇
  2007年   478篇
  2006年   421篇
  2005年   367篇
  2004年   318篇
  2003年   307篇
  2002年   235篇
  2001年   190篇
  2000年   187篇
  1999年   140篇
  1998年   180篇
  1997年   170篇
  1996年   146篇
  1995年   113篇
  1994年   104篇
  1993年   97篇
  1992年   89篇
  1991年   97篇
  1990年   88篇
  1989年   73篇
  1988年   73篇
  1987年   67篇
  1986年   67篇
  1985年   105篇
  1984年   83篇
  1983年   64篇
  1982年   70篇
  1981年   61篇
  1980年   47篇
  1979年   35篇
  1978年   30篇
  1977年   29篇
  1976年   15篇
  1970年   11篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
21.
45 patients with spinocerebellar degeneration (SCD) underwent through quantitative investigation of the ventricular and cisternal systems by CT scanning and threshold vibrometry in the limbs to find out whether these parameters could be used for distinguishing mainly spinal from cerebellar forms or from olivopontoce-rebellar atrophy. The increase in the vibration sense threshold and the mild atrophy in the posterior cranial fossa proved typical of spinal forms and the reverse for cerebellar forms. In olivopontocerebellar atrophy enlargement of the cisterns and dilatation of the ventricles always exceeded 85% of normal values.
Sommario 45 pazienti affetti da degenerazione spinocerebellare (SCD) sono stati sottoposti ad uno studio approfondito di esplorazione quantitativa del sistema ventricolare e cisternale alla TAC e della soglia di percezione vibratoria agli arti per valutare la possibilità di distinguere con questi parametri le forme prevalentemente spinali da quelle cerebellari o delle atrofie olivopontocerebellari. L'aumento della soglia vibratoria e la modesta atrofia in fossa posteriore è risultata tipica delle forme spinali, mentre l'inverso si verifica per le forme cerebellari. Nelle atrofie olivopontocerebellari l'allargamento delle cisterne e la dilatazione dei ventricoli supera quasi sempre l'85% rispetto ai casi normali.
  相似文献   
22.
The histological findings of the patellar cartilage were compared between cases of chondromalacia, which occurs predominantly in young persons (22 patients, average age 19.8 years) and cases of osteoarthritis, which is common among the elderly (21 patients, average age 65.4 years). The histological findings of cartilage in the chondromalacia were characterized by increased density and vigorous fibrous metaplasia of chondrocytes. These findings may be considered to represent a reactive change in the chondrocyte. Cartilage degeneration in osteoarthritis, by contrast, is regressive and presents a clearly different histological picture from that of chondromalacia patellae. We conclude that chondromalacia does not easily lead to osteoarthritis. On the other hand, the cartilage was characteristically softened, as observed by gross inspection, and showed rarefaction of the cartilage matrix. It should be noted that the change was not observed in aging, but showed a pattern of cartilage degeneration peculiar to young patients with chondromalacia patellae.  相似文献   
23.
探刊干性型老年黄斑变性(age-related macular deganeration,AMD)的病变发展特征并 寻找监测AMD病情进展的较敏感指标。 方法:用眼底彩色照相和眼底荧光血管造影(FFA)、明视视网膜电囤(ERG)、FM100-hue 色彩试验及视力检查,对60例(111眼)50~80岁、视力≤1.0的干性型AMD患者进行3~74个月(平均30.2个月)的随访观察。 结果:本组68眼经FFA检查、平均25.6个月随访,其中25%的患眼病灶损害有快慢不一的发展.全部111眼视力在平均30.2个月随访中有18%患眼的视力下降2行以下,且与病灶进展相符,FM100-hue 色彩试验的被随访者中,随访2年以后,其总错误分明显的增加(P<0.01).63眼的明视ERG在随访过程中无明显变化。 结论:大部分干性AMD患眼的病灶损害和视力可以在较长时间内维持稳定。FM100—hue的总错误分可能为监测AMD病情进展的较敏感指标. (中华眼底病杂志,1997,13:150-152)  相似文献   
24.
The aim of this study was to evaluate the potential for restoration of a large cartilage defect in the goat knee with hydroxyapatite (HA) loaded with chondrocytes. Isolated chondrocytes were suspended in fibrin glue, seeded on top of the HA, and then the composite graft was implanted in the defect. After transplantation, cell behaviour, newly synthesised matrix and the HA–glue interface were assessed histologically after 2, 4, 12, 26 and 52 weeks. Special attention was paid to the incorporation process of HA in the subchondral bone and interactions between this biomaterial and the fibrin-glue–chondrocyte suspension.

Chondrocytes in the glue proved to survive the transplantation procedure and produced new metachromatically stained matrix two weeks after implantation. The glue–cell suspension had penetrated the superficial porous structure of the HA. Four weeks after surgery, islands of hyaline-like cartilage were observed at the HA–glue interface. A layer of fibrous tissue was formed surrounding the HA graft, resulting in a relatively instable fixation of the HA in the defect. This instability of the graft in the defect, possibly together with early weight bearing, resulted in a gradual loss of the newly formed hyaline cartilage-like repair tissue. Progressive resorption of the HA occurred without any sign of active bone remodelling from the host site. One year after surgery part of the defect which extended down to the cancellous bone had been predominantly restored with newly formed lamellar bone. Only small HA remnants were still present at the bottom of the original defect. Resurfacing of the joint had occurred with fibrocartilaginous repair tissue.

The absence of adequate fixation capacity of the HA near the joint space resulted in a relative instability of the graft with progressive resorption. Therefore, HA is not a suitable biomaterial to facilitate the repair of large articular cartilage defects.  相似文献   

25.
We studied the effects of Wallerian degeneration in the cerebral peduncle shown by magnetic resonance imaging (MRI) following a supratentorial vascular lesion, to identify the somatotopic localisation of the descending cortical tracts. Patients with a lesion involving a large area of a cerebral hemisphere had an area of abnormal signal intensity in the whole cerebral peduncle, suggesting Wallerian degeneration of all the whole descending cortical tracts. With a small lesion confined to the precentral gyrus, corona radiata, or posterior limb of the internal capsule there was an abnormal signal at the centre of the peduncle, suggesting degeneration of the precentrospinal tract. Those with a small lesion confined to the paracentral gyrus had an abnormal area slightly lateral to the centre of the peduncle, suggesting degeneration of the parietospinal tract. Patients with a lesion of the parietal or temporal lobes, not including the paracentral or precentral gyri, corona radiata, or the posterior limb of the internal capsule, had an abnormal area laterally in the peduncle, suggesting degeneration of the parietopontine or temporopontine tract.  相似文献   
26.
在家兔的股骨内髁上作一关节软骨全层缺损,且从同侧胫骨近端取下一片骨膜骨块,将骨膜生发层向外包绕骨块,嵌入缺损处,观察其作用。实验表明,骨膜在一定条件下可以化生成软骨;滑液环境与关节运动在软骨化生过程中起重要作用;透明软骨化生和再生率与运动量及开始时间相关;自体骨可作为一种将游离骨膜固定在软骨缺损内的填充材料。  相似文献   
27.
Summary Groups of adult male mice were either fed a thiamine-deficient diet for 10 weeks and thereafter treated with ethanol by making them inhale vapourized cane spirit for 10 weeks, or given both treatments simultaneously. The brains of these mice were then searched for degeneration using both light and electron microscopy. No degenerating nerve cells were observed in any animal in the cerebral cortex, hippocampus, cerebellum, olfactory bulbs, midbrain or hindbrain. However, axon terminal degeneration was seen in the olfactory bulbs and deep cerebellar nuclei in mice given the combined treatment. No cerebellar degeneration was found and only little degeneration was present in the olfactory bulbs of mice given the two treatments at different times. Thus, the combined treatment of alcohol and thiamine deficiency produced more brain damage than the sum of that produced by the two treatments given separately. This represents the first experimental in vivo demonstration of a biochemical interaction between these two factors in alcohol-related brain damage. The findings of long-term animal treatment with models using thiamine antagonists are compared.Supported by the special Research Fund Programme of Monash University (Post-Doctoral Fellowship)  相似文献   
28.
We report a case of a 68‐year‐old right‐handed man with sporadic amyotrophic lateral sclerosis (ALS) and argyrophilic grain disease (AGD) having a 22‐month duration. His initial symptoms were dysarthria and swallowing difficulty at the age of 67. Subsequently bulbar palsy and pyramidal signs developed. His cognitive functions including face recognition, personality, and behavior were not changed compared with that of before the disease onset. However, magnetic resonance imaging disclosed severe right side‐predominant temporal atrophy. The neurological diagnosis was bulbar type ALS. Pathological examination disclosed histological evidence of ALS, including loss of Betz cells and lower motor neurons, corticospinal tract degeneration, and Bunina bodies. In addition, severe neuronal loss in the bilateral temporal cortex with an anterior gradient was found. Ubiquitin‐positive inclusions were encountered in the spinal anterior horn cells and hippocampal dentate gyrus, while few ubiquitin‐positive inclusions were noted in the affected temporal cortex. The amygdala, especially the basolateral nuclear group, was severely affected by neuronal loss with tissue rarefaction. Moderate neuronal loss was encountered in the parahippocampal gyrus, and to a lesser degree, in the ambient gyrus. Unexpectedly, many argyrophilic grains, coiled bodies, tau‐positive bush‐like astrocytes, pretangles, and ballooned neurons were found in the limbic system and temporal cortex. In the hippocampus, selective tau accumulation with minor neurofibrillary changes was observed in CA2 neurons. The present case suggests that (i) ALS and AGD do rarely coexist, and (ii) when ALS patients have severe temporal atrophy, not only ALS with dementia but also concurrent AGD should be considered in the differential diagnosis.  相似文献   
29.
黄武君  谈志龙  白人骁 《中国骨伤》2007,20(10):635-638
骨性关节炎是最常见关节疾患之一,是导致中老年残疾的最常见原因,严重危害着中老年人的生活质量。骨性关节炎的主要病理是软骨的改变,软骨细胞分解和合成活动的平衡有助于维持软骨细胞外基质结构和功能的完整性,而软骨细胞的这种平衡受到细胞因子制约,本文就近年来细胞因子与OA软骨退变之间的研究现状综述。  相似文献   
30.
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