全文获取类型
收费全文 | 9569篇 |
免费 | 442篇 |
国内免费 | 52篇 |
专业分类
耳鼻咽喉 | 178篇 |
儿科学 | 368篇 |
妇产科学 | 82篇 |
基础医学 | 1371篇 |
口腔科学 | 117篇 |
临床医学 | 644篇 |
内科学 | 2279篇 |
皮肤病学 | 286篇 |
神经病学 | 736篇 |
特种医学 | 319篇 |
外科学 | 1437篇 |
综合类 | 32篇 |
一般理论 | 1篇 |
预防医学 | 254篇 |
眼科学 | 159篇 |
药学 | 682篇 |
中国医学 | 31篇 |
肿瘤学 | 1087篇 |
出版年
2023年 | 47篇 |
2022年 | 108篇 |
2021年 | 181篇 |
2020年 | 124篇 |
2019年 | 137篇 |
2018年 | 211篇 |
2017年 | 181篇 |
2016年 | 178篇 |
2015年 | 187篇 |
2014年 | 262篇 |
2013年 | 290篇 |
2012年 | 478篇 |
2011年 | 598篇 |
2010年 | 365篇 |
2009年 | 343篇 |
2008年 | 529篇 |
2007年 | 560篇 |
2006年 | 560篇 |
2005年 | 618篇 |
2004年 | 615篇 |
2003年 | 586篇 |
2002年 | 511篇 |
2001年 | 164篇 |
2000年 | 149篇 |
1999年 | 164篇 |
1998年 | 139篇 |
1997年 | 109篇 |
1996年 | 95篇 |
1995年 | 105篇 |
1994年 | 88篇 |
1993年 | 86篇 |
1992年 | 103篇 |
1991年 | 96篇 |
1990年 | 82篇 |
1989年 | 97篇 |
1988年 | 88篇 |
1987年 | 66篇 |
1986年 | 60篇 |
1985年 | 72篇 |
1984年 | 71篇 |
1983年 | 40篇 |
1982年 | 47篇 |
1981年 | 34篇 |
1979年 | 46篇 |
1978年 | 39篇 |
1977年 | 27篇 |
1972年 | 31篇 |
1970年 | 43篇 |
1969年 | 30篇 |
1968年 | 30篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
72.
Yoshihisa Kurachi Toshiaki Nakajima Tsuneaki Sugimoto 《Pflügers Archiv : European journal of physiology》1987,410(3):227-233
The short-term desensitization of the acetylcholine (ACh)-induced K+ channel current was examined in single atrial cells of guinea-pig heart. The tight-seal whole cell voltage clamp technique was used. The solution in the pipettes contained GTP or guanosine-5-O-(3-thiotriphosphate) (GTP-S, a non-hydrolyzable GTP analogue). In GTP-loaded cells, ACh evoked a specific K+ channel current via GTP-binding proteins (G) in a dose-dependent manner. The K+ current showed agonist-dependent desensitization similar to those reported in other cardiac tissues (Nilius 1983; Carmeliet and Mubagwa 1986). The cellular response to ACh was also desensitized by activation of P1-purinergic receptors with adenosine (Ado). In GTP-S-loaded cells, the K+ current was gradually induced even in the absence of agonists, probably due to direct activation of G proteins by GTP-S. In the early phase of the spontaneous current increase, ACh evoked a large current transiently. As the GTP-S-induced activation of the current progressed, the magnitude of the ACh-evoked current transient became smaller and finally negligible. Similar results were obtained when Ado was used as an agonist instead of ACh to induce the K+ current. Therefore, it is indicated that the agonistreceptor interaction may not be essential for the desensitization of ACh-induced K+ current in atrial myocytes. 相似文献
73.
Teramoto T Kobayashi M Mizutani H Sugiura Y Ueda M 《Archives of histology and cytology》2001,64(1):51-58
The present study was performed to examine changes in the arrangement of D-periodic collagen fibrils in the synovium of the growing temporomandibular joint in mice. At 1 week of age, the mandibular condyle was undeveloped, and only a few collagen fibrils were recognizable in the subintimal layer of the synovium. At 8 weeks, the mandibular condyle was structurally developed with an increase of collagen fibrils in the synovium; a fully mature condyle was observed at 6 months of age. The close association of proteoglycans with collagen fibrils in the synovium of the growing joint was examined by both conventional and energy-filtering transmission electron microscopy of cupromeronic blue-stained specimens. Proteoglycans were associated with D-periodic collagen fibrils in the short filamentous form in random fashion at 1 week of age, but in a regular pattern with D-periodicity at 6 months. These associations in the synovium could be correlated with the mechanical character of the temporomandibular joint. 相似文献
74.
Seiiohi Sumino Kazuo Nacsashima Tetsuro Shimamine Toshiaki Abe Hideo Tsuneyoshi Satoru Murao 《Pathology international》1983,33(3):629-643
Autopsy findings in a 40-year-old male with heredofamilial amyloidosis and polyneuropathy are reported. He had been suffering from progressive autonomic as well as sensorimotor dysfunctions. Prominent amyloid deposit was found in the kidney, heart, thyroid, and testis, and less in the interstitium and small vessels of almost all organs. The peripheral nerves, some showing prominent hypertrophy, were most severely involved by amyloid deposit in a form of stellate mass, which ultrastructurally consisted of radially arranged amyloid filaments. In the hypertrophied nerves and ganglia, in addition to amyloid, massive accumulation of acid mucopolysaccharide (AMPS) was seen filling up the interstitial space, which was the cause of hypertrophy. Ultrastructurally, AMPS was seen as finely granular substance. An extracted amyloid from the kidney showed 8 nm filament on negative staining and was estimated of having a molecular weight of 14,000. 相似文献
75.
A common Ile796Val polymorphism of the human SREBP cleavage-activating protein (SCAP) gene 总被引:3,自引:0,他引:3
We identified a new common amino acid polymorphism of isoleucine/valine at codon 796 in exon 16 of the gene for human sterol
regulatory element binding protein (SREBP) cleavage-activating protein (SCAP), a central regulator of lipid synthesis and
metabolism in animal cells. It can be detected as an MslI restriction fragment length polymorphism. The allelic frequencies were: isoleucine (A) allele, 0.57 and valine (G) allele,
0.43. This polymorphism may be useful for genetic studies of disorders affecting intracellular lipid metabolism and hyperlipidemia.
Received: August 17, 1999 / Accepted: August 19, 1999 相似文献
76.
Hiroshi Kimoto Hitoshi Nagaoka Yoshihiro Adachi Toshiaki Mizuochi Takachika Azuma Takenori Yagi Tetsutaro Sata Shin Yonehara Yasuko Tsunetsugu-Yokota Masaru Taniguchi Toshitada Takemori 《European journal of immunology》1997,27(1):268-279
Well-developed germinal centers (GC) contain rapidly dividing surface immunoglobulin-negative (sIg-) B cells (centroblasts), and most of their progeny are sIg+ B cells (centrocytes) in a resting state. It has been predicted that somatic hypermutation occurs in centroblasts, whereas antigen-driven selection takes place in centrocytes. The present analysis indicates that murine GC B cells bearing sIg with specificity for an immunizing antigen are in a rapidly cycling state and increase exponentially in number to occupy spleen GC at high frequency during the 1st week after primary immunization; however, the number of these cells is significantly reduced in the 2nd week of immunization. During that period, these proliferating sIg+ GC B cells accumulate somatic hypermutations with nucleotide exchanges indicative of affinity maturation. These sIg+ GC B cells co-express B7-2, ICAM-1, and LFA-1, and have potent antigen-presenting activity which results in T cell activation in vitro. These observations indicate that the sIg+ GC B cells accumulate somatic hypermutations and undergo antigen-driven selection through proliferation, probably upon activation by T cells. This sIg+ GC B cell population may represent cell cycling centrocytes; however, the possibility that these may represent centroblasts undergoing re-expression of sIg could not be excluded. 相似文献
77.
78.
79.
The pathogenesis of progressive bile duct loss in primary biliary cirrhosis remains unclear. In this study, the involvement of cellular senescence of biliary epithelial cells was examined in liver tissue samples from patients with primary biliary cirrhosis (n = 33), and compared with control diseased and normal livers (n = 83). In addition, cellular senescence was induced by oxidative stress in cultured mouse biliary epithelial cells. Biliary epithelial cells in small bile ducts in primary biliary cirrhosis, especially those in patients presenting with chronic non-suppurative cholangitis, frequently expressed senescence-associated beta-galactosidase, and senescence-associated p16(INK4) and p21(WAF1/CIP). In contrast, senescence-associated markers were rarely expressed in small bile ducts in control livers. The infiltration of myeloperoxidase-positive inflammatory cells into biliary epithelial cell layers was closely associated with the cellular senescence of biliary epithelial cells in early-stage PBC. Cellular senescence of cultured mouse biliary epithelial cells was induced by treatment with H2O2 via the p38MAPK-dependent pathway and nitric oxide-augmented H2O2-induced cellular senescence. Oxidative stress- and nitric oxide-mediated cellular senescence may be involved in bile duct lesions, which are followed by progressive bile duct loss in primary biliary cirrhosis. 相似文献
80.