全文获取类型
收费全文 | 54396篇 |
免费 | 2529篇 |
国内免费 | 293篇 |
专业分类
耳鼻咽喉 | 469篇 |
儿科学 | 1039篇 |
妇产科学 | 736篇 |
基础医学 | 6905篇 |
口腔科学 | 1271篇 |
临床医学 | 3564篇 |
内科学 | 13693篇 |
皮肤病学 | 1034篇 |
神经病学 | 4070篇 |
特种医学 | 1879篇 |
外科学 | 9687篇 |
综合类 | 219篇 |
一般理论 | 4篇 |
预防医学 | 1623篇 |
眼科学 | 1054篇 |
药学 | 3878篇 |
中国医学 | 153篇 |
肿瘤学 | 5940篇 |
出版年
2023年 | 278篇 |
2022年 | 600篇 |
2021年 | 1068篇 |
2020年 | 576篇 |
2019年 | 776篇 |
2018年 | 989篇 |
2017年 | 770篇 |
2016年 | 933篇 |
2015年 | 1076篇 |
2014年 | 1338篇 |
2013年 | 1585篇 |
2012年 | 2648篇 |
2011年 | 2785篇 |
2010年 | 1613篇 |
2009年 | 1334篇 |
2008年 | 2483篇 |
2007年 | 2698篇 |
2006年 | 2637篇 |
2005年 | 2817篇 |
2004年 | 2833篇 |
2003年 | 2630篇 |
2002年 | 2653篇 |
2001年 | 1837篇 |
2000年 | 1734篇 |
1999年 | 1736篇 |
1998年 | 798篇 |
1997年 | 629篇 |
1996年 | 585篇 |
1995年 | 520篇 |
1994年 | 475篇 |
1993年 | 455篇 |
1992年 | 1082篇 |
1991年 | 1005篇 |
1990年 | 893篇 |
1989年 | 978篇 |
1988年 | 825篇 |
1987年 | 739篇 |
1986年 | 784篇 |
1985年 | 716篇 |
1984年 | 472篇 |
1983年 | 407篇 |
1982年 | 231篇 |
1981年 | 225篇 |
1979年 | 339篇 |
1978年 | 271篇 |
1977年 | 230篇 |
1975年 | 220篇 |
1974年 | 195篇 |
1973年 | 183篇 |
1971年 | 181篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
21.
Evidence by cellular mosaicism for monoclonal metastasis of spontaneous mouse mammary tumors 总被引:2,自引:0,他引:2
Female (SHN X C3H/He)F1 mice carrying spontaneous mammary tumors with cellular mosaicism with respect to isozymes of phosphoglycerate kinase (PGK) showed a high incidence of lung metastases. On resection of successively appearing mammary tumors, mice survived a maximum of 8 tumors. In these mice with multiple primary mammary tumors and multiple metastases, not only each individual metastasis but also all the metastases in the same lung had the same pattern of PGK isozymes and the same histologic type in the PGK-mosaic background of the host, indicating the monoclonal origin of these metastases. In several cases, this single pattern of metastatic colonies coincided with that of only one of several primary tumors, indicating that this tumor had metastasized. In these cases, these tumors were not necessarily the earliest of the primary tumors, and they were not located in any particular site. 相似文献
22.
H Tsukuma A Oshima T Hiyama I Fujimoto H Yamano M Tanaka 《International journal of epidemiology》1987,16(4):579-583
In order to examine time trends of the prevalences of HBeAg positives among HBV carriers in Japan, we analysed data on HBeAg of HBsAg positive voluntary blood donors (23,560 males, and 8659 females) at the Osaka Red Cross Blood Centre between January 1977 and March 1984. Age-specific prevalences of HBeAg positives decreased year by year for both sexes, especially for those in their teens and twenties. The prevalences of HBeAg positives decreased with age, but at any given age it was lower for the later than for the earlier birth cohorts. Although reasons for the secular declines are unknown, the findings suggest that the prevalence of HBeAg positives among HBV carriers will continue to decrease in Japan. This, together with the immunization programme implemented this year, may lead to a future reduction in the risk of HBV related liver diseases in Japan. 相似文献
23.
K Tanaka Y Miyake S Sasaki Y Ohya S Miyamoto I Matsunaga T Yoshida Y Hirota H Oda 《Magnesium research》2006,19(4):268-275
There have only been a few studies on the role of mineral intake in tooth loss. We investigated the association between mineral intake and the prevalence of tooth loss in Japan. We used the baseline data on 1002 pregnant women who were enrolled in the Osaka Maternal and Child Health Study between November 2001 and March 2003. Tooth loss was defined as the previous extraction of one or more teeth. Nutrient intake was assessed by a validated diet history questionnaire. Prevalence odds ratios and confidence intervals were estimated by applying a multiple logistic regression model. The adjusted odds ratio upon comparison of the highest quartile with the lowest quartile of magnesium intake was 0.64 (95% confidence interval, 0.42-0.99), showing a tendency for an inverse dose-response relationship (p for linear trend = 0.05). There were no associations between the level of consumption of calcium, phosphate, iron, zinc, or copper and tooth loss. The present findings suggest that intake of magnesium is related to reduced prevalence of tooth loss among young Japanese women. 相似文献
24.
Soichiro Yoshida Tetsuo Hayashi Makoto Morozumi Hisato Osada Norinari Honda Takumi Yamada 《International journal of urology》2007,14(7):665-667
The incidence of stonestreet formation after extracorporeal shock wave lithotripsy (ESWL) rises with increasing stone burden. However, stonestreet after ESWL is often experienced even in stones smaller than 20 mm. To examine whether the non-contrast helical computed tomography (CT) data could predict stonestreet formation in these stones, 53 radiopaque stones of 5-20 mm treated with ESWL were evaluated. Maximal dimension was measured on plain radiograph. From an attenuation value histogram graphed from the CT data, total stone volume and mean attenuation value were calculated. Seven stonestreets longer than 25 mm developed. There was no significant difference in maximal dimension and total stone volume between stones that did and stones that did not develop stonestreet. Mean attenuation value was the sole significant predictive factor. Application of mean attenuation value with cut-off level of 650 HU would anticipate stonestreet formation with a sensitivity of 85.7% and a specificity of 71.7%. The estimated risk of stonestreet formation is high in the treatment of stones with higher mean attenuation value. 相似文献
25.
Seiichi Saito Shunichi Namiki Kenji Numahata Makoto Satoh Shigeto Ishidoya Akihiro Ito Haruo Nakagawa Yasuhiro Kaiho Takehiko Sanada Atsushi Yamada Yoichi Arai 《International journal of urology》2007,14(2):133-139
PURPOSE: To determine the effect of an interposition nerve graft on sexual function after radical prostatectomy. METHODS: This study includes 64 patients, without hormonal therapy, who underwent a radical prostatectomy and intraoperative electrophysiological confirmation of cavernous nerve preservation. Twelve patients underwent a unilateral interposition sural nerve graft (UNG) for the resected neurovascular bundle. Twenty-one and 31 patients underwent bilateral nerve-sparing (BNS) and unilateral nerve-sparing (UNS) surgery without a nerve graft, respectively. As the age of patients was significantly younger in the UNG group than in the other groups, age-matched analysis also was conducted. Sexual function, evaluated by a self-administered questionnaire using the University of California Los Angeles-Prostate Cancer Index, was compared statistically among the three groups. RESULTS: In the age-matched analysis, the postoperative sexual function (SXF) score of the UNG group showed an intermediate level of recovery between those of the BNS and UNS groups at 12 months and reached the same level as the score at 12 months of the BNS group at 18 months postoperatively. The difference in the SXF score between the UNG and UNS groups began to appear after 6 months postoperatively and increased steadily with time. However, the background factors, such as the baseline SXF score, the usage rate of phosphodiesterase 5 inhibitors, and the rate of comorbidities were different between the UNG and UNS groups. CONCLUSIONS: The difference of the SXF score between the UNG and UNS groups increased with time after 6 months postoperatively. However, it might be difficult at present to attribute a better recovery of the SXF score to the nerve graft because of the difference in the background factors between the groups. 相似文献
26.
A 68-year-old man had subacute cerebellar degeneration and a non-Hodgkin's lymphoma. Using an immunoblotting method, we found serum antibodies to rat cerebral 250-kd and 110-kd and cerebellar 110-kd acidic cytoplasmic proteins. The antibodies did not react unless the antigens were prepared soon after death with protease inhibitors. Two hundred fifty-kd and 110-kd proteins are minor components of soluble cytoplasmic proteins of the brain. The molecular weights differed from other soluble brain-specific proteins already characterized. 相似文献
27.
Hiroko Utsunomiya Wanninayake M. Tilakaratne Kazufumi Oshiro Satoshi Maruyama Makoto Suzuki Hiroko Ida-Yonemochi Jun Cheng Takashi Saku 《Journal of oral pathology & medicine》2005,34(8):498-507
BACKGROUND: Oral submucous fibrosis (OSF) is a chewing habit-related pre-cancerous condition of the oral mucosa affecting predominantly south Asians. It is histopathologically characterized by epithelial atrophy and fibrosis of the subepithelial connective tissue. Fibrosis extends all the way into the muscle layer, leading to difficulty in mouth opening. However, the dynamics of extracellular matrix (ECM) remodeling with OSF progression is largely unknown. METHODS: Forty biopsy specimens of OSF and 10 of normal buccal mucosa were examined for expression/deposition modes of eight ECM molecules by histochemistry, immunohistochemistry, and in situ hybridization. RESULTS: In the early stage of OSF, tenascin, perlecan, fibronectin, collagen type III were characteristically enhanced in the lamina propria and the submucosal layer. In the intermediate stage, the ECM molecules mentioned above and elastin were extensively and irregularly deposited around muscle fibers. In the advanced stage, such ECM depositions decreased and were entirely replaced with collagen type I only. Their gene expression levels varied with progression of fibrosis, but the mRNA signals were confirmed in fibroblasts in the submucosal fibrotic areas. CONCLUSIONS: The results indicate that the ECM remodeling steps in OSF are similar to each phase of usual granulation tissue formation. Restricted mouth opening may be a result of loss of variety of ECM molecules including elastin into the homogeneity of collagen type I replacing muscle fibers. 相似文献
28.
29.
Electrical stimulation of several brain sites produces profound analgesia in humans, and inhibits nocifensor reflexes in animal studies. Responses of the dorsal horn nociceptive neurons evoked by stimulation onto the receptive fields are also inhibited by brain stimulation. These brain sites are Periaqueductal Gray Matter (PAG), Nucleus Raphe Magnus (NRM), Nucleus Reticularis magnocellularis (NRmc), Locus Coeruleus (LC), Lateral Hypothalamus, and others. We have explained in a general way the mechanism of these stimulation produced analgesia. The mechanism of PAG stimulation analgesia is partly due to an activation of serotonin containing neurons which descend from NRM to the spinal dorsal horn and activated by PAG stimulation. Activation of NRM neurons may produce inhibition of the nociceptive neurons of the dorsal horn by the mechanism of direct postsynaptic inhibition. Currently there is no evidence to support the theory of presynaptic inhibition. Endogenous opioid peptides do not play an important role in PAG stimulation analgesia. On the other hand, the mechanism of NRmc or LC stimulation analgesia may be due to an activation of noradrenaline containing neurons which similarly inhibit the dorsal horn nociceptive neurons in the spinal cord. At present, it still remains unknown whether endogenous opioid peptides play an important role in this type of analgesia. 相似文献
30.
Y Taki T Morimoto A Tanaka M Noguchi W Y Wang T Nishihira K Nishikawa K Mori K Ozawa 《The Journal of surgical research》1990,48(1):56-60
Ketogenic capacity of mitochondria from the remnant liver of 70% hepatectomized rats was studied in relation to mitochondrial phosphorylative activity. Ketogenic capacity increased to a maximum of 6.04 +/- 0.39 from 3.84 +/- 0.13 of control, with an enhancement of mitochondrial phosphorylative activity 6 hr after hepatectomy, and then decreased to normal levels within 24 hr. Adenylate energy charge, (ATP + 1/2ADP)/(ATP + ADP + AMP), of the remnant liver decreased to 0.825 +/- 0.006 as compared to 0.849 +/- 0.002 of control 6 hr after operation. At 12 hr, total ketone body concentrations of the arterial blood increased concomitant with a fall in ketone body ratio (acetoacetate/3-hydroxybutyrate) which reflects the decreased liver mitochondrial redox (NAD+/NADH) state. These findings suggest that an enhancement of mitochondrial fatty acid oxidation and ketogenesis occurs concomitant with an enhancement of mitochondrial phosphorylative activity in the remnant liver in response to a decreased energy charge after 70% hepatectomy. 相似文献