全文获取类型
收费全文 | 6466篇 |
免费 | 327篇 |
国内免费 | 44篇 |
专业分类
耳鼻咽喉 | 55篇 |
儿科学 | 104篇 |
妇产科学 | 72篇 |
基础医学 | 806篇 |
口腔科学 | 79篇 |
临床医学 | 358篇 |
内科学 | 1676篇 |
皮肤病学 | 129篇 |
神经病学 | 539篇 |
特种医学 | 427篇 |
外科学 | 1308篇 |
综合类 | 30篇 |
一般理论 | 1篇 |
预防医学 | 168篇 |
眼科学 | 62篇 |
药学 | 386篇 |
中国医学 | 13篇 |
肿瘤学 | 624篇 |
出版年
2023年 | 27篇 |
2022年 | 31篇 |
2021年 | 159篇 |
2020年 | 85篇 |
2019年 | 108篇 |
2018年 | 139篇 |
2017年 | 134篇 |
2016年 | 146篇 |
2015年 | 136篇 |
2014年 | 191篇 |
2013年 | 231篇 |
2012年 | 386篇 |
2011年 | 432篇 |
2010年 | 260篇 |
2009年 | 233篇 |
2008年 | 418篇 |
2007年 | 399篇 |
2006年 | 443篇 |
2005年 | 422篇 |
2004年 | 390篇 |
2003年 | 357篇 |
2002年 | 340篇 |
2001年 | 119篇 |
2000年 | 96篇 |
1999年 | 111篇 |
1998年 | 91篇 |
1997年 | 55篇 |
1996年 | 63篇 |
1995年 | 64篇 |
1994年 | 51篇 |
1993年 | 60篇 |
1992年 | 71篇 |
1991年 | 58篇 |
1990年 | 48篇 |
1989年 | 66篇 |
1988年 | 51篇 |
1987年 | 42篇 |
1986年 | 29篇 |
1985年 | 38篇 |
1984年 | 32篇 |
1983年 | 18篇 |
1982年 | 22篇 |
1981年 | 17篇 |
1980年 | 14篇 |
1979年 | 17篇 |
1978年 | 13篇 |
1977年 | 11篇 |
1973年 | 12篇 |
1972年 | 12篇 |
1968年 | 13篇 |
排序方式: 共有6837条查询结果,搜索用时 17 毫秒
101.
Ultrastructural study of M cells from colonic lymphoid nodules obtained by colonoscopic biopsy 总被引:4,自引:0,他引:4
Dr. Yoshinori Fujimura MD Masayo Hosobe MD Tsuyoshi Kihara MD 《Digestive diseases and sciences》1992,37(7):1089-1098
The present study was undertaken to investigate ultrastructurally the epithelium covering lymphoid nodules obtained from colonoscopic biopsies of the human colon and rectum. Colonoscopy using the dye spraying contrast, method was performed in nine patients who showed x-ray evidence of lymphonodular hyperplasia. Fifty-two colonoscopical biopsy specimens, of lymphoid nodules were obtained from the ascending, transverse, and descending colon and rectosigmoid region. All specimens were observed by light and electron microscopy. Light microscopy disclosed large lymphoid follicles protruding into the lumen with a dome-type configuration. These extended to the lamina propria of the mucosa and were associated with a massive lymphoid aggregation extending as far as the muscularis mucosa from the submucosa. The epithelium covering these nodules contained a few goblet cells and many lymphocytes. Observation of the elevated surface at the apex by scanning electron microscopy revealed M cells with sparse microvilli in the dome epithelium surrounded by crypts. Transmission electron microscopy disclosed M cells enfolding many immature or mature lymphocytes and plasmocytes. The M cells had cytoplasmic microvilli (so-called microfolds) on their surfaces, well-developed tubulovesicular systems, and vacuoles in the cytoplasm. The basic structure of the M cells as observed by scanning and transmission electron microscopy was the same as that of M cells in the Peyer's patches of humans and mice. The apical surface of the colonic lymphoid follicles in Crohn's disease patients was associated with erosions observed by scanning electron microscopy. The erosions proved to be the naked surface of the dome after removal of the epithelium and many holes from 2.0 to 6.0 m in diameter were observed on the naked surface. At high magnification, lymphocytes were seen projecting from holes (18%) on the naked surface of the dome. These ultrastructural findings indicate that human colonic lymphoid follicles are very similar to those seen in other species. 相似文献
102.
103.
Inoue K Okada K Taki Y Goto R Kinomura S Kaneta T Fukuda H 《Hepato-gastroenterology》2008,55(81):46-49
BACKGROUND/AIMS: The serum tumor marker carbohydrate associated antigen 19-9 (CA19-9) has been used for screening for cancer, because its increase has been associated with many cancers. We aimed to evaluate the clinical value of positron emission tomography using F-18 fluorodeoxyglucose (18FDG-PET) that was prompted by increases of serum CA19-9 without findings on conventional imaging. METHODOLOGY: Twenty-two patients were retrospectively selected. Eleven were without a history of cancer and eleven had a history of cancer and were treated with curative intent. All 18FDG-PET findings were compared with the findings of histopathology by surgery or biopsy, or clinical follow-up for at least 1 year. RESULTS: We found only two true positive cases, and eleven cases without a cancer history included 10 true negatives and one false positive. CONCLUSIONS: Increases in serum CA19-9 are caused by many benign conditions. Increases of CA19-9 without findings on conventional imaging do not justify 18FDG-PET examination, particularly in patients without a cancer history. 相似文献
104.
Fukukawa Y Nakashima C Tsuboi S Niino N Ando F Kosugi S Shimokata H 《The journals of gerontology. Series B, Psychological sciences and social sciences》2004,59(1):P19-P26
In this study, we compared the impact of health problems (HPs) on everyday activities and depressive symptoms between middle-aged and older adults. We also examined what type and source of social interactions moderate the noxious effects of HPs. Longitudinal analyses of data with 1,802 Japanese community-dwelling adults indicated that HPs were significantly related to (a) an increase in depressive symptoms among middle-aged adults and (b) a decline in everyday activities among older adults. The former was buffered by emotional family support, whereas the latter (b) was buffered by instrumental family support and, surprisingly, by negative interactions with family. In contrast, social interactions with other friends and acquaintances did not show any moderating effect. 相似文献
105.
106.
Yasuyuki Shiraishi Shun Kohsaka Takayuki Abe Kazumasa Harada Tetsuro Miyazaki Takamichi Miyamoto Kiyoshi Iida Shuzou Tanimoto Mayuko Yagawa Makoto Takei Yuji Nagatomo Toru Hosoda Takeshi Yamamoto Ken Nagao Morimasa Takayama 《The American journal of medicine》2018,131(2):156-164.e2
Background
The onset of acute heart failure is known to be associated with increased physical activity and other specific behaviors that can trigger hemodynamic deterioration. This analysis aimed to describe the distribution of triggers in patients hospitalized for acute heart failure, and investigate their effects on in-hospital outcomes.Methods
Consecutive patients hospitalized for acute heart failure between 2010 and 2014 were registered in a multicenter data registration system (72 institutions within Tokyo, Japan). Baseline demographics and in-hospital mortality were extracted from 17,473 patients. Patients with a trigger were grouped based on their triggering event: those with onset during (a) physical activity; (b) sleeping; (c) eating or watching television; (d) bathing or excretion (use of restrooms); and (e) engaging in other activities. These patients were compared with patients without identifiable triggers. Multiple imputation was used for missing data.Results
Patients were predominantly men (57.1%), with a mean age of 76.0 ± 13.0 years; a triggering event was present in 49.1%. No significant difference in baseline characteristics was noted between groups except for younger age, higher blood pressure, and prevalence of signs of congestion in the trigger-positive group. In-hospital mortality rate was 7.9%. Presence of triggers was positively associated with a reduced risk of in-hospital mortality (adjusted odds ratio 0.79; 95% confidence interval, 0.70-0.90; P = .0003). In a delta-adjusted pattern mixture model, the effect of a triggering event on in-hospital mortality remained consistently significant.Conclusion
Triggering events for acute heart failure can provide additional information for risk prediction. Efforts to identify the triggers should be made to classify patients according to risk group. 相似文献107.
Yoshiharu Sada Yoshihiro Dohi Sayuri Uga Akifumi Higashi Hiroki Kinoshita Yasuki Kihara 《Heart and vessels》2016,31(8):1319-1326
Regulatory T cells (Tregs) have been reported to play a pivotal role in the vascular remodeling of pulmonary arterial hypertension (PAH). Recent studies have revealed that Tregs are heterogeneous and can be characterized by three phenotypically and functionally different subsets. In this study, we investigated the roles of Treg subsets in the pathogenesis of PAH in eight patients with PAH and 14 healthy controls. Tregs and their subsets in peripheral blood samples were analyzed by flow cytometry. Treg subsets were defined as CD4+CD45RA+FoxP3low resting Tregs (rTregs), CD4+CD45RA?FoxP3high activated Tregs (aTregs), and CD4+CD45RA?FoxP3low non-suppressive Tregs (non-Tregs). The proportion of Tregs among CD4+ T cells was significantly higher in PAH patients than in controls (6.54 ± 1.10 vs. 3.81 ± 0.28 %, p < 0.05). Of the three subsets, the proportion of non-Tregs was significantly elevated in PAH patients compared with controls (4.06 ± 0.40 vs. 2.79 ± 0.14 %, p < 0.01), whereas those of rTregs and aTregs were not different between the two groups. Moreover, the expression levels of cytotoxic T lymphocyte antigen 4, a functional cell surface molecule, in aTregs (p < 0.05) and non-Tregs (p < 0.05) were significantly higher in PAH patients compared with controls. These results suggested the non-Treg subset was expanded and functionally activated in peripheral lymphocytes obtained from IPAH patients. We hypothesize that immunoreactions involving the specific activation of the non-Treg subset might play a role in the vascular remodeling of PAH. 相似文献
108.
Humic acid induces the endothelial nitric oxide synthase phosphorylation at Ser1177 and Thr495 Via Hsp90α and Hsp90β upregulation in human umbilical vein endothelial cells 下载免费PDF全文
Masato Tanaka Miki Miyajima Naoko Hishioka Ryo Nishimura Yusuke Kihara Toshiyuki Hosokawa Masaaki Kurasaki Shunitz Tanaka Takeshi Saito 《Environmental toxicology》2015,30(2):223-231
Humic acid (HA) has been implicated as a contributory factor for blackfoot disease, which is an endemic peripheral vascular disease. We investigated the effect of HA on the regulation of endothelial nitric oxide (NO) synthase (eNOS) in human umbilical vein endothelial cells (HUVECs) to evaluate the involvement of eNOS and related factors in peripheral vascular impairment with HA exposure. Treatment of HUVECs with HA induced upregulation of eNOS. This result coincides with those of previous studies. Furthermore this is the first study to report that HA induces upregulation of heat shock protein (Hsp)90α, Hsp90β, eNOS phosphorylation at Ser1177, and eNOS phosphorylation at Thr495, as compared to that in the control. In contrast, treatment with BAPTA, an intracellular Ca2+ chelator, inhibited upregulation of these proteins induced by HA. This study demonstrates that HA treatment leads to increases in both Hsp90α and Hsp90β proteins and indicates that Hsp90α leads to eNOS phosphorylation at Ser1177 and that Hsp90β leads to eNOS phosphorylation at Thr495, respectively. Upregulation of eNOS, Hsp90α, and Hsp90β in HUVECs is regulated by intracellular Ca2+ accumulation induced by HA. These results suggest that upregulation of eNOS phosphorylation at Ser1177 and eNOS phosphorylation at Thr495 produce NO and superoxide anions, respectively, resulting in generation of peroxynitrite, which causes impairment of vascular endothelial cells. © 2013 Wiley Periodicals, Inc. Environ Toxicol 30: 223–231, 2015. 相似文献
109.
Kihara Mari Sugihara Takahiko Asano Junichi Sato Midori Kaneko Hiroshi Muraoka Sei Ohshima Shiro Nanki Toshihiro 《Clinical rheumatology》2022,41(12):3661-3673
Clinical Rheumatology - To describe clinical characteristics of patients in Japan with coronavirus disease 19 (COVID-19) and pre-existing rheumatic disease and examine the possible risk factors... 相似文献
110.
Arita Y Kihara S Ouchi N Maeda K Kuriyama H Okamoto Y Kumada M Hotta K Nishida M Takahashi M Nakamura T Shimomura I Muraguchi M Ohmoto Y Funahashi T Matsuzawa Y 《Circulation》2002,105(24):2893-2898
BACKGROUND: Vascular smooth muscle cell proliferation plays an important role in the development of atherosclerosis. We previously reported that adiponectin, an adipocyte-specific plasma protein, accumulated in the human injured artery and suppressed endothelial inflammatory response as well as macrophage-to-foam cell transformation. The present study investigated the effects of adiponectin on proliferation and migration of human aortic smooth muscle cells (HASMCs). Methods and Results- HASMC proliferation was estimated by [(3)H] thymidine uptake and cell number. Cell migration assay was performed using a Boyden chamber. Physiological concentrations of adiponectin significantly suppressed both proliferation and migration of HASMCs stimulated with platelet-derived growth factor (PDGF)-BB. Adiponectin specifically bound to (125)I-PDGF-BB and significantly inhibited the association of (125)I-PDGF-BB with HASMCs, but no effects were observed on the binding of (125)I-PDGF-AA or (125)I-heparin-binding epidermal growth factor (EGF)-like growth factor (HB-EGF) to HASMCs. Adiponectin strongly and dose-dependently suppressed PDGF-BB-induced p42/44 extracellular signal-related kinase (ERK) phosphorylation and PDGF beta-receptor autophosphorylation analyzed by immunoblot. Adiponectin also reduced PDGF-AA-stimulated or HB-EGF-stimulated ERK phosphorylation in a dose-dependent manner without affecting autophosphorylation of PDGF alpha-receptor or EGF receptor. CONCLUSIONS: The adipocyte-derived plasma protein adiponectin strongly suppressed HASMC proliferation and migration through direct binding with PDGF-BB and generally inhibited growth factor-stimulated ERK signal in HASMCs, suggesting that adiponectin acts as a modulator for vascular remodeling. 相似文献