全文获取类型
收费全文 | 4200篇 |
免费 | 314篇 |
国内免费 | 4篇 |
出版年
2021年 | 40篇 |
2020年 | 21篇 |
2019年 | 32篇 |
2018年 | 42篇 |
2017年 | 52篇 |
2016年 | 78篇 |
2015年 | 94篇 |
2014年 | 125篇 |
2013年 | 206篇 |
2012年 | 190篇 |
2011年 | 219篇 |
2010年 | 129篇 |
2009年 | 111篇 |
2008年 | 187篇 |
2007年 | 199篇 |
2006年 | 196篇 |
2005年 | 179篇 |
2004年 | 215篇 |
2003年 | 178篇 |
2002年 | 173篇 |
2001年 | 156篇 |
2000年 | 166篇 |
1999年 | 126篇 |
1998年 | 50篇 |
1997年 | 55篇 |
1996年 | 44篇 |
1995年 | 53篇 |
1994年 | 42篇 |
1993年 | 36篇 |
1992年 | 99篇 |
1991年 | 90篇 |
1990年 | 76篇 |
1989年 | 87篇 |
1988年 | 78篇 |
1987年 | 89篇 |
1986年 | 62篇 |
1985年 | 76篇 |
1984年 | 51篇 |
1983年 | 34篇 |
1982年 | 36篇 |
1981年 | 31篇 |
1979年 | 36篇 |
1978年 | 20篇 |
1977年 | 22篇 |
1975年 | 16篇 |
1974年 | 23篇 |
1973年 | 28篇 |
1971年 | 17篇 |
1967年 | 15篇 |
1966年 | 17篇 |
排序方式: 共有4518条查询结果,搜索用时 31 毫秒
131.
H. Yoshida Shigeyuki Fujita Tadahiko Iizuka Toshimichi Yoshida Teruyo Sakakura 《Histochemistry and cell biology》1997,107(6):479-484
The expression of tenascin (TN) in the temporomandibular joint (TMJ) disc and synovial membrane was examined in 18 human
TMJ samples from patients with internal derangement of the TMJ and ten control specimens by an immunohistological technique
using paraffin-embedded tissue and specific anti-human TN monoclonal antibody (RCB-1). The expression of TN was observed in
all 28 samples, but it was limited to the walls of blood vessels, the perineurium, and the surface of the TMJ disc. The expression
of TN was diffuse in the stroma of mildly hypertrophic synovial membranes and focal in the surface of severely hypertrophic
synovial membranes. The clinical symptoms of internal derangement of the TMJ are thought to be related to the degree of synovitis.
The present study demonstrates that TN is expressed specifically in the portion of the TMJ synovial membrane affected with
internal derangement.
Accepted: 17 December 1996 相似文献
132.
133.
The mechanisms of cell death in CD4+ T cells mediated by human herpesvirus 6 (HHV-6) were investigated. The frequency of cell death in the human CD4+ T-cell line JJHAN, which had been inoculated with HHV-6 variant A or B, appeared to be augmented by tumor necrosis factor alpha (TNF-alpha). Agarose gel electrophoresis of DNA from HHV-6-inoculated cells showed DNA fragmentation in multiples of the oligonucleosome length unit. The degree of DNA fragmentation increased when HHV-6-inoculated cells were cultured in the presence of TNF-alpha. Flow cytometry and Scatchard analysis of TNF receptors revealed an increase in the number of the p55 form of TNF receptors on JJHAN cells after HHV-6 inoculation. It also appeared that treatment with anti-Fas monoclonal antibody (MAb) induced marked apoptosis in HHV-6-inoculated cells. Transmission electron microscopy showed characteristics of apoptosis, such as chromatin condensation and fragmentation of nuclei, but virus particles were hardly detected in apoptotic cells. Two-color flow cytometric analysis using anti-HHV-6 MAb and propidium iodide revealed that DNA fragmentation was present predominantly in uninfected cells but not in productively HHV-6-infected cells. In addition, JJHAN cells incubated with UV light-irradiated and ultracentrifuged culture supernatant of HHV-6-infected cells appeared to undergo apoptosis. The present study demonstrated that both HHV-6 variants A and B induce apoptosis in CD4+ T cells by indirect mechanisms, as reported recently in human immunodeficiency virus type 1 infection. 相似文献
134.
Hiromi Takahashi-Iwanaga Toshihiko Iwanaga Yuzuru Sakamoto Tsuneo Fujita 《Cell and tissue research》1995,280(3):491-497
In previous ultrastructural studies we have shown that at the tip of intestinal villi in guinea pigs, effete enterocytes are separated into two portions: a thin apical cytoplasm to be exfoliated into the lumen and a major basal portion to be ingested by lamina propria macrophages. During this process, intraepithelially disposed, large granular lymphocytes interdigitate with enterocytes in a complex manner. In the present study, the relation between the enterocytes and the lymphocytes in the villous epithelium of the guinea pig small intestine is described by use of transmission and scanning electron microscopy in an attempt to visualize the roles and activities of the lymphocytes more clearly. The lymphocytes project numerous pointed processes into effete enterocytes, even piercing them. Enterocytes are deeply indented or perforated, probably as a result of the encroaching lymphocyte processes. Some enterocytes are separated into apical and basal portions by numerous large excavations in the cytoplasm. These findings indicate that repeated perforating penetration of the lymphocytes induces cell cleavage. Supporting this supposition, our microcinematographic observations demonstrate the alternate protrusion and withdrawal of processes of lymphocytes. The processes advance with a pointed end, and subsequently, retract with a rounded end in a cycle of 8–18 seconds. 相似文献
135.
Z. I. Bhatti K. Furukawa M. Fujita 《World journal of microbiology & biotechnology》1995,11(6):631-637
A laboratory upflow anaerobic sludge blanket reactor, seeded with fine, suspended, bacterial floc with 1.76 g volatile suspended solids/l, was used to treat synthetic methanolic waste. After 180 days of continuous peration, granular sludge with discrete granules of 1 to 2 mm diam. was formed, with 52 g volatile suspended solids/l. Granules were brown, relatively soft and had a settling velocity of 1.61 cm/s. Extracellular polymeric matter extracted from the granular sludge had high carbohydrate content but low nucleic acid content. The ash of the granular sludge contained Na+, K+ and Mg2+ up to 15.0, 11.7 and 3.75 mg/g, respectively. Scanning and transmission electron microscopy revealed that the granular sludge was dominated by methanogens resembling Methanosarcina.The authors are with the Department of Environmental Engineering, Faculty of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565, Japan 相似文献
136.
T Fujita 《Tanpakushitsu kakusan koso. Protein, nucleic acid, enzyme》1984,29(14):1928-1936
137.
Cell-free synthesis of ornithine decarboxylase. Changes in mRNA activity in the liver of thioacetamide-treated rats 总被引:1,自引:0,他引:1
T Kameji K Fujita T Noguchi M Takiguchi M Mori M Tatibana S Hayashi 《European journal of biochemistry》1984,144(1):35-39
Ornithine decarboxylase (ODC)mRNA associated with free polysomes of rat liver was translated in a reticulocyte lysate cell-free system. Newly synthesized ODC protein was identified by specific immunoprecipitation, molecular size as determined by polyacrylamide gel electrophoresis with sodium dodecyl sulfate, and competition by excess unlabeled ODC in the immunoprecipitation. A single injection of thioacetamide was found to cause several fold increases in both immunotitratable ODC protein and polysomal ODC-mRNA activity, while it provoked a much larger increase in ODC activity in rat liver. The results indicate that the induction of hepatic ODC activity by thioacetamide treatment is due not only to an increase in the activity of polysomal ODC-mRNA but also to a translational and/or posttranslational control. 相似文献
138.
E Sato M Fujie T Uezato M Fujita K Nishimura 《Biochemical and biophysical research communications》1984,119(3):1168-1173
The composition of intestinal glycosphingolipids during normal and hormone-perturbed development was investigated. The concentrations of glycosphingolipids of mouse small intestine were affected by the injection of thyroxine or cortisone during suckling and weaning periods. GDla was reduced by the hormonal treatment among major gangliosides, GM3, GM1 and GD1a, of mouse small intestine during the suckling period. In contrast, asialo GM1 was precociously produced by the treatment, which scarcely found in control suckling mouse small intestine. The results showed that these hormones were related to developmental alteration of small-intestinal glycolipids. 相似文献
139.
Antizyme to ornithine decarboxylase is present in the liver of starved rats. 总被引:1,自引:1,他引:0 下载免费PDF全文
Antizyme to ornithine decarboxylase (ODC) and ODC-antizyme complex were both present in liver cytosols of starved rats. The antizyme was identified by its molecular weight, kinetic properties, formation of a complex with ODC, and reversal of its inhibition by antizyme inhibitor. The average amount of antizyme in liver cytosols of starved rats was 0.1 unit/mg of protein, roughly corresponding to basal hepatic ODC activity in rats fed ad libitum. The presence of ODC-antizyme complex was detected by using antizyme inhibitor. These results indicate that antizyme participates in the regulation of ODC activity in vivo under physiological conditions. 相似文献
140.
Stimulation of prostaglandin E2 synthesis by exogenous phospholipase A2 and C in rabbit kidney medulla slices. 下载免费PDF全文
We have investigated the effects of phospholipase A2 and C on the synthesis of prostaglandin E2 in rabbit kidney medulla and the release of fatty acids from the medulla slices. Exogenous phospholipase A2 [from Naja naja (Indian cobra) venom] and phospholipase C (from Clostridium welchii) stimulated prostaglandin E2 production in a dose-dependent manner. At the maximal effective concentrations (0.5 unit of phospholipase A2/ml, 2 units of phospholipase C/ml), phospholipase C increased prostaglandin E2 formation to the level observed with phospholipase A2. Phospholipase A2 enhanced the release only of unsaturated fatty acids, whereas phospholipase C stimulated the release of individual free fatty acids (C 16:0, C 18:0, C 18:1, C 18:2 and C 20:4). Moreover, p-bromophenacyl bromide inhibited phospholipase A2-stimulated prostaglandin E2 production and the release of fatty acids, but it had no influence on prostaglandin E2 formation and the release of fatty acids increased by phospholipase C, indicating that the stimulatory effect of phospholipase C is not mediated through the activation of endogenous phospholipase A2. These results suggest the presence of diacylglycerol lipase and monoacylglycerol lipase in the kidney and the importance of this pathway in prostaglandin synthesis by the kidney. 相似文献