全文获取类型
收费全文 | 57117篇 |
免费 | 5428篇 |
国内免费 | 2083篇 |
出版年
2021年 | 1123篇 |
2020年 | 909篇 |
2019年 | 1068篇 |
2018年 | 1145篇 |
2017年 | 1014篇 |
2016年 | 1328篇 |
2015年 | 1740篇 |
2014年 | 2123篇 |
2013年 | 2331篇 |
2012年 | 2715篇 |
2011年 | 2627篇 |
2010年 | 1735篇 |
2009年 | 1660篇 |
2008年 | 2084篇 |
2007年 | 1971篇 |
2006年 | 1918篇 |
2005年 | 1656篇 |
2004年 | 1549篇 |
2003年 | 1504篇 |
2002年 | 1397篇 |
2001年 | 3062篇 |
2000年 | 2696篇 |
1999年 | 1982篇 |
1998年 | 723篇 |
1997年 | 617篇 |
1996年 | 549篇 |
1995年 | 463篇 |
1994年 | 482篇 |
1992年 | 1329篇 |
1991年 | 1197篇 |
1990年 | 1133篇 |
1989年 | 1075篇 |
1988年 | 957篇 |
1987年 | 944篇 |
1986年 | 820篇 |
1985年 | 825篇 |
1984年 | 576篇 |
1983年 | 528篇 |
1979年 | 634篇 |
1978年 | 453篇 |
1977年 | 416篇 |
1975年 | 494篇 |
1974年 | 573篇 |
1973年 | 555篇 |
1972年 | 569篇 |
1971年 | 550篇 |
1970年 | 520篇 |
1969年 | 525篇 |
1968年 | 426篇 |
1966年 | 409篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
102.
103.
104.
105.
The light-microscopic and ultrastructural characteristics of the temporomandibular joints (TMJs) of female STR/IN mice, aged from 3 to 12 months, were studied. Every TMJ of an adult mouse starts to degenerate in early adulthood and subsequently suffers from osteo-arthrosis. Ageing of the TMJ is characterized by thinning out of its cartilaginous components. The chondrocytes are no longer distributed regularly in the ground substance but form clusters. Cracks and fissures invade the condylar cartilage and lead to the formation of cartilage islands, which finally become loose as free bodies in the lower joint chamber and joint capsule. The lower joint chamber diminishes, but no ankylosis is observed. Ultrastructurally, the number of vesicles around the degenerated chondrocytes increases. Aged chondrocytes contain more lysosomes. The condylar surface becomes irregular and reveals microscars. Its surface is covered by an electron-dense fine granular material, considered to be built up by proteoglycans. Compared to the male ICR mouse, the osteo-arthrotic destruction of the cartilage, the subchondral sclerosis and the deformation of the underlying bone exhibit only minor states in the female STR/IN mouse. Concerning the aetiology and pathogenesis, the very early degeneration of the mostly unloaded TMJ seems to be based on a genetically altered composition of the articular cartilage, possibly due to failing articular chondrocyte responses to stimuli connected with degeneration and repair. 相似文献
106.
Metabolic processes in the uterus damaged in different parts of its innervation were studied. The specificity of neurodystrophic processes in the uterus depends on the nature of the injury to its innervation. Combination of different methods of modern morphological analysis made it possible to reveal hypoplastic processes in all the layers of the uterus. 相似文献
107.
108.
109.
110.
Using electron microscopic cytochemistry and immunoelectron microscopy, the ultrastructure of bone marrow (BM) cells of the subendosteal region with a high colony-forming (CFUs) ability was studied. In comparison with the central part of BM, the subendosteal region of CBA and BALB/c mice contains a higher number of lymphocyte-like mononuclears, bearing an antigen, common with the brain surface one but negative for peroxidase and acid and alkaline phosphatase. The ultrastructure of these cells is similar to that of presumptive hematopoietic stem cells. In the subendosteal region mononuclears are concentrated with the lower nucleo-cytoplasmic ratio, a feston-like line of the nucleus and more numerous organoids. These cells are characteristic of BM myeloid islands composed of granulocytes being on various stages of differentiation, and of reticular cells positive for alkaline phosphatase. 相似文献