全文获取类型
收费全文 | 6221篇 |
免费 | 312篇 |
国内免费 | 64篇 |
专业分类
耳鼻咽喉 | 53篇 |
儿科学 | 95篇 |
妇产科学 | 18篇 |
基础医学 | 802篇 |
口腔科学 | 195篇 |
临床医学 | 330篇 |
内科学 | 1648篇 |
皮肤病学 | 160篇 |
神经病学 | 289篇 |
特种医学 | 253篇 |
外科学 | 1067篇 |
综合类 | 34篇 |
预防医学 | 252篇 |
眼科学 | 82篇 |
药学 | 429篇 |
中国医学 | 38篇 |
肿瘤学 | 852篇 |
出版年
2023年 | 33篇 |
2022年 | 22篇 |
2021年 | 141篇 |
2020年 | 75篇 |
2019年 | 107篇 |
2018年 | 109篇 |
2017年 | 125篇 |
2016年 | 155篇 |
2015年 | 150篇 |
2014年 | 188篇 |
2013年 | 248篇 |
2012年 | 397篇 |
2011年 | 409篇 |
2010年 | 241篇 |
2009年 | 221篇 |
2008年 | 373篇 |
2007年 | 436篇 |
2006年 | 439篇 |
2005年 | 471篇 |
2004年 | 430篇 |
2003年 | 418篇 |
2002年 | 407篇 |
2001年 | 71篇 |
2000年 | 55篇 |
1999年 | 101篇 |
1998年 | 98篇 |
1997年 | 76篇 |
1996年 | 92篇 |
1995年 | 56篇 |
1994年 | 38篇 |
1993年 | 48篇 |
1992年 | 40篇 |
1991年 | 30篇 |
1990年 | 34篇 |
1989年 | 45篇 |
1988年 | 32篇 |
1987年 | 26篇 |
1986年 | 17篇 |
1985年 | 17篇 |
1984年 | 25篇 |
1983年 | 11篇 |
1982年 | 12篇 |
1981年 | 9篇 |
1980年 | 6篇 |
1979年 | 13篇 |
1978年 | 7篇 |
1977年 | 6篇 |
1976年 | 6篇 |
1975年 | 7篇 |
1967年 | 4篇 |
排序方式: 共有6597条查询结果,搜索用时 78 毫秒
101.
102.
Kitaoka H Kuwahara T Nishida K Morimoto K Kubo T Okawa M Furuno T Doi Y 《Journal of cardiology》2005,45(4):155-159
A 41-year-old man was referred to our hospital for further examination because of abnormal electrocardiography findings at a health-check examination. Transthoracic echocardiography showed left ventricular hypertrophy confined to the most distal portion of the left ventricle, which is a typical feature of apical hypertrophic cardiomyopathy. Ten years later, he was again admitted for the evaluation of chest pain. Echocardiography showed asymmetrical septal hypertrophy in addition to apical hypertrophy. These findings demonstrate morphologic evolution in hypertrophic cardiomyopathy from apical hypertrophy to asymmetrical septal hypertrophy. 相似文献
103.
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
104.
Morinaga S Yamamoto Y Noguchi Y Imada T Rino Y Akaike M Sugimasa Y Takemiya S Takanashi Y 《Hepato-gastroenterology》2003,50(53):1521-1526
BACKGROUND/AIMS: Platelet-derived endothelial cell growth factor (PD-ECGF) is one of the angiogenic factors. The aim of this study was to examine the PD-ECGF concentrations in hepatocellular carcinoma, background liver, and normal liver tissues, and to elucidate their significance on clinicopathological outcomes. METHODOLOGY: The concentration of PD-ECGF in the tissue extract was determined by enzyme-linked immunosorbent assay. RESULTS: PD-ECGF concentrations were significantly higher in hepatocellular carcinoma and background liver tissues compared with normal control liver (p = 0.003, p = 0.001, respectively). PD-ECGF concentrations in hepatocellular carcinoma tissues were positively correlated with intratumoral arteriole densities (r = 0.667, p = 0.009), and were higher in less differentiated carcinomas (p = 0.039). However, tumor PD-ECGF concentration did not affect the patients' disease-free survival rates. Those in the background liver tissues were positively correlated with histological activity index scores (r = 0.650, p = 0.001) and serum alanine aminotransferase levels (r = 0.0452, p = 0.035). CONCLUSIONS: PD-ECGF is up-regulated in hepatocellular carcinoma and the corresponding hepatitis liver. The PD-ECGF concentrations in hepatocellular carcinoma correlated positively with microvessel density, lower differentiation, yet not with patients' prognosis. The concentrations of PD-ECGF in the corresponding hepatitis liver correlated positively with the degree of active hepatitis. 相似文献
105.
Mori M Imagawa T Katakura S Miyamae T Okuyama K Ito S Nakamura T Kimura H Yokota S 《Modern rheumatology / the Japan Rheumatism Association》2004,14(1):43-47
Kawasaki disease (KD) causes coronary artery lesions (CALs) in 500 Japanese children each year. Intravenous gamma-globulin (IVGG) decreases the incidence of these lesions from 25% to 8% of the total KD cases. We examined whether plasma exchange is a safe and effective prophylaxis against CALs in children with KD intractable to IVGG therapy. Eighty-nine children with KD at high risk of CALs were selected on the basis of increases in fractional changes in inflammatory markers such as white blood cell count, neutrophil count, and C-reactive protein between the baseline and 1–2 days after IVGG treatment. Of 105 children who received a second course of IVGG therapy because the initial course was ineffective, plasma exchange (PE) was performed in 46 children who had not responded to the second IVGG treatment. The outcome was compared with the results when a third course of IVGG therapy was given to the other 59 children. No complications occurred with the plasma exchange therapy. CALs developed in only 8 of the 46 children (17.3%) who underwent plasma exchange, but they occurred in 24 of the 59 (40.7%) who had received a third course of IVGG therapy (P 0.0012). We concluded that PE was a safe, effective prophylactic measure against CALs in children with KD intractable to IVGG therapy. PE should be performed at an early stage, as soon as fractional increases in inflammatory markers are found after IVGG therapy. 相似文献
106.
Fukuhara K Osugi H Takada N Takemura M Lee S Morimura K Taguchi S Kaneko M Tanaka Y Fujiwara Y Nishizawa S Fukushima S Kinoshita H 《Hepato-gastroenterology》2004,51(59):1515-1518
BACKGROUND/AIMS: Helicobacter pylori infection is known to induce gastritis, oxidative stress, and cyclooxygenase (COX)-2 expression in the gastric mucosa. However, the effect of H. pylori infection on remnant gastritis has not been studied. We investigated whether the severity of remnant gastritis and COX-2 expression were affected by H. pylori infection after distal gastrectomy. METHODOLOGY: The study included 97 patients with gastric cancer who underwent curative distal gastrectomy with lymphadenectomy in our department between May 1999 and April 2001. All patients underwent endoscopic examination 2 weeks before and 12 weeks after surgery. The presence of H. pylori infection was determined by urease activity, hematoxylin-eosin staining, and immunochemical staining. Histologic remnant gastritis was graded based on the degree of neutrophil infiltration using the updated Sydney System. COX-2 expression was estimated immunohistochemically. RESULTS: Both the degree of neutrophil infiltration and the level of COX-2 expression were significantly higher in patients with than without H. pylori (p<0.05). There was a significant correlation between the degree of neutrophil infiltration and the degree of COX-2 expression (p<0.001). CONCLUSIONS: H. pylori eradication may become a treatment for preventing both remnant gastritis as well as remnant gastric carcinoma after distal gastrectomy. 相似文献
107.
Toll-like receptor 9 signaling mediates the anti-inflammatory effects of probiotics in murine experimental colitis 总被引:31,自引:0,他引:31
Rachmilewitz D Katakura K Karmeli F Hayashi T Reinus C Rudensky B Akira S Takeda K Lee J Takabayashi K Raz E 《Gastroenterology》2004,126(2):520-528
BACKGROUND & AIMS: We tested whether the attenuation of experimental colitis by live probiotic bacteria is due to their immunostimulatory DNA, whether toll-like receptor (TLR) signaling is required, and whether nonviable probiotics are effective. METHODS: Methylated and unmethylated genomic DNA isolated from probiotics (VSL-3), DNAse-treated probiotics and Escherichia coli (DH5 alpha) genomic DNA were administered intragastrically (i.g.) or subcutaneously (s.c.) to mice prior to the induction of colitis. Viable or gamma-irradiated probiotics were administered i.g. to wild-type mice and mice deficient in different TLR or in the adaptor protein MyD88, 10 days prior to administration of dextran sodium sulfate (DSS) to their drinking water and for 7 days thereafter. RESULTS: Intragastric and s.c. administration of probiotic and E. coli DNA ameliorated the severity of DSS-induced colitis, whereas methylated probiotic DNA, calf thymus DNA, and DNase-treated probiotics had no effect. The colitis severity was attenuated to the same extent by i.g. delivery of nonviable gamma-irradiated or viable probiotics. Mice deficient in MyD88 did not respond to gamma-irradiated probiotics. The severity of DSS-induced colitis in TLR2 and TLR4 deficient mice was significantly decreased by i.g. administration of gamma-irradiated probiotics, whereas, in TLR9-deficient mice, gamma-irradiated probiotics had no effect. CONCLUSIONS: The protective effects of probiotics are mediated by their own DNA rather than by their metabolites or ability to colonize the colon. TLR9 signaling is essential in mediating the anti-inflammatory effect of probiotics, and live microorganisms are not required to attenuate experimental colitis because nonviable probiotics are equally effective. 相似文献
108.
Up-regulation of transferrin receptor 1 in chronic hepatitis C: Implication in excess hepatic iron accumulation. 总被引:3,自引:0,他引:3
Hiroyuki Saito Yoshinori Fujimoto Takaaki Ohtake Yasuaki Suzuki Shinobu Sakurai Yayoi Hosoki Katsuya Ikuta Yoshihiro Torimoto Yutaka Kohgo 《Hepatology research》2005,31(4):203-210
BACKGROUND/AIMS:: To clarify the mechanism of excess hepatic iron accumulation in chronic hepatitis C, we investigated the expressions of transferrin receptor 1 and divalent metal transporter 1 in hepatocytes, both of which are involved in cellular iron uptake, in relation to the degree of hepatic iron accumulation and hepatic fibrosis by immunohistochemistrical study. METHODS:: Forty-six hepatic tissues with chronic hepatitis C and five normal hepatic tissues were examined. Chemical detection of hepatic iron accumulation was performed by Perl's Prussian blue stain. The immunohistochemistrical study was performed by avidin-biotin complex method with alkaline phosphatase. RESULTS:: In chronic hepatitis C: (1) Hepatic iron accumulation was significantly increased in relation to the advance of the fibrosis. (2) Divalent metal transporter 1 decreased significantly in relation to the advance of hepatic fibrosis. (3) Transferrin receptor 1 expression was always detected, although not in normal hepatic tissues; there was no relation between expression levels and the degree of hepatic fibrosis. CONCLUSIONS:: These data demonstrated that the transferrin receptor 1 expression was up-regulated irrespective of the degree of hepatic iron accumulation, suggesting that the up-regulation of transferrin receptor 1 might act as one of the key mechanisms implicated in the accumulation of hepatic iron in chronic hepatitis C. 相似文献
109.
Inhibitory effect of ceramide on insulin-induced protein kinase Czeta translocation in rat adipocytes 总被引:2,自引:0,他引:2
Miura A Kajita K Ishizawa M Kanoh Y Kawai Y Natsume Y Sakuma H Yamamoto Y Yasuda K Ishizuka T 《Metabolism: clinical and experimental》2003,52(1):19-24
Ceramide has been confirmed to be a signal mediator of apoptosis that is induced by tumor necrosis factor-alpha (TNF-alpha). It has also been reported that ceramide may induce insulin resistance as well as TNF-alpha. We investigated the effect of ceramide on insulin signaling pathways, such as insulin receptor (IR) beta-subunit, insulin receptor substrate 1 (IRS-1), phosphatidylinositol 3-kinase (PI3K), and protein kinase Czeta (PKCzeta) in rat adipocytes. We examined insulin-stimulated [(3)H]2-deoxyglucose (2-DOG) uptake in rat adipocytes pretreated with N-hexanoylsphingosine (C(6)-ceramide, 10 to 30 micromol/L). Insulin-induced 2-DOG uptake was significantly reduced by C(6)-ceramide pretreatment. We also examined the effect of various concentrations of C(6)-ceramide pretreatment on insulin-induced autophosphorylation of the IR beta-subunit, tyrosine phosphorylation of IRS-1, enzyme activity of PI3K, and membrane-associated PKCzeta immunoreactivity. Pretreatment with C(6)-ceramide significantly reduced autophosphorylation of the IR beta-subunit, tyrosine phosphorylation of IRS-1, and enzyme activity of PI3K. Moreover, membrane-associated PKCzeta immunoreactivity and immunoprecipitable PKCzeta enzyme activity, downstream of PI3K, were significantly suppressed by C(6)-ceramide pretreatment. These results suggest that ceramide may induce insulin resistance via the suppression of IRS-1-PI3K signaling, and subsequent activation of PKCzeta. 相似文献
110.
Black (or brown) adrenal cortical adenoma: its characteristic features on computed tomography and endocrine data 总被引:3,自引:0,他引:3
I Komiya N Takasu T Aizawa T Yamada Y Koizumi K Hashizume M Ishihara K Hiramatsu K Ichikawa M Katakura 《The Journal of clinical endocrinology and metabolism》1985,61(4):711-717
Seventeen patients with adrenal adenoma causing Cushing's syndrome, eight patients with Cushing's disease due to hypersecretion of ACTH, and five patients with primary aldosteronism due to an aldosteronoma were studied for their computed tomographic (CT) patterns, hormonal profiles, and macroscopic and microscopic findings of the adrenal gland. Black (or brown) adrenal adenomas were found in 71% of the patients with Cushing's syndrome, but not in patients with aldosteronoma. The adrenal tissue of patients with Cushing's disease was predominantly yellow. The number of compact cells was larger in black or brown adenomas than in yellow tumors or hyperplastic adrenal tissue. In patients with Cushing's syndrome, urinary excretion of 17-ketosteroids (17-KS) and serum aldosterone concentrations were lower in those with black or brown adenomas than in those with yellow adenomas (P less than 0.05). Patients with Cushing's disease had even higher 17-KS and serum aldosterone levels. No difference was found in serum cortisol concentrations and dexamethasone suppressibility in two types of adenomas causing Cushing's syndrome. Visual estimation of radiological density of the adrenal tissue relative to the kidney on CT scan and quantitative measurement of it by CT number revealed a difference between the two types of adrenal tumors causing Cushing's syndrome. Adrenal tumors with decreased density on CT scan were yellow adenomas with predominantly clear cells, and those with equal or increased density were black or brown adenomas with predominantly compact cells. All aldosteronomas had decreased density and consisted of clear cells. It is suggested that black or brown adenomas of the adrenal gland have higher radiological density and accompanying lower serum aldosterone and urinary 17-KS levels than ordinary yellow tumors. The abundance of compact cells may have some significance for the development of this particular type of adrenal tumor. 相似文献