首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   4792篇
  免费   323篇
  国内免费   35篇
耳鼻咽喉   82篇
儿科学   114篇
妇产科学   45篇
基础医学   576篇
口腔科学   121篇
临床医学   423篇
内科学   1342篇
皮肤病学   31篇
神经病学   324篇
特种医学   207篇
外科学   809篇
综合类   23篇
一般理论   1篇
预防医学   124篇
眼科学   154篇
药学   249篇
中国医学   3篇
肿瘤学   522篇
  2024年   11篇
  2023年   99篇
  2022年   177篇
  2021年   315篇
  2020年   152篇
  2019年   168篇
  2018年   191篇
  2017年   146篇
  2016年   179篇
  2015年   156篇
  2014年   174篇
  2013年   239篇
  2012年   369篇
  2011年   418篇
  2010年   201篇
  2009年   139篇
  2008年   237篇
  2007年   244篇
  2006年   203篇
  2005年   199篇
  2004年   170篇
  2003年   172篇
  2002年   161篇
  2001年   24篇
  2000年   32篇
  1999年   37篇
  1998年   32篇
  1997年   26篇
  1996年   28篇
  1995年   29篇
  1994年   28篇
  1993年   20篇
  1992年   38篇
  1991年   25篇
  1990年   31篇
  1989年   35篇
  1988年   19篇
  1987年   19篇
  1986年   24篇
  1985年   16篇
  1984年   20篇
  1983年   20篇
  1982年   13篇
  1981年   10篇
  1980年   11篇
  1977年   8篇
  1976年   11篇
  1975年   13篇
  1974年   16篇
  1973年   8篇
排序方式: 共有5150条查询结果,搜索用时 93 毫秒
61.
Cadmium and zinc concentrations were determined in the tissues and organs, including the fetus, of striped dolphins. The kidney showed the highest cadmium concentration and the hepatic cadmium concentration was also relatively high. A similar distribution pattern among soft tissues was also observed with zinc, where its concentration varied less than that of cadmium. A significant positive correlation between zinc and cadmium was found in both the kidney and the liver; the increase of zinc concentration with cadmium was more marked in the liver (Zn:Cd 3∶1 on molar basis) than kidney (Zn:Cd 1∶1). Negligible cadmium concentration in the fetus suggested that cadmium is not transferred to the fetus via the placenta from the mother. Organ-specific age trends of cadmium and zinc concentrations were presented in detail for muscle, liver, kidney, pancreas, brain, and blood. Both metals showed rapid change during the periods of the fetus and weaning.  相似文献   
62.
Summary Aprindine is a class Ib antiarrhythmic agent. We studied effects of aprindine (3 µmol/l) on the Na+ current using whole cell voltage clamp (tip resistance = 0.5 , [Na]i ando = 10 mmol/l at 18°C). Aprindine revealed tonic block (Kdrest = 37.7 µmol/l, Kdi = 0.74 µmol/l; n = 4). Aprindine, shifted inactivation curve to hyperpolarizing direction by 11.4 ± 3.5 mV (n = 4) without changes in slope factor. In the presence of 3 µmol/l aprindine, aprindine showed phasic block, i.e., duration-dependent block at 2 Hz (64% ±3070 at 1.5 ms, 82%±6% at 20 ms, 93%±7% at 200 ms; n = 4). Short single prepulse also produced aprindine-induced phasic block (12% at 1.5 ms, 22% at 100 ms; n = 2). After removal of fast inactivation of Na+ current by 3 mmol/l tosylchloramide sodium, aprindine revealed phasic block, independent of holding potential. The recovery time constant from aprindine-induced phasic block was 4.8 s at holding potential = –100 mV and 5.0 s at holding potential = –140 mV. This use-dependent block of aprindine had pH dependency. Under acidic condition (pH 6.0), 3 µmol/l aprindine showed smaller use-dependent block (14% ± 7% at 2 Hz; n = 4) comparing with either at pH 7,4 (68% ± 13%; n = 4) or at pH 8.0 (90% ±12%; n = 4).The results suggest that aprindine could bind to the receptor via activation process through channel pore, resulting in decrease of Na+ current, and egress from the receptor through the lipid bilayer. These effects might be attenuated under acidic condition due to changes in intracellular ratio of charged to neutralized form of drug molecule. Send offprint requests to: R. Sato at the above address  相似文献   
63.
The intravenous secretin injection test (secretin test) has been used for the differential diagnosis of gastrinoma. In this study we report that the intraoperative secretin test (IOS test) is also useful for determining the extent of curability in patients with Zollinger-Ellison syndrome (ZES). Twelve patients with ZES underwent surgical exploration and the IOS test. The results of the IOS test were obtained by rapid radioimmunoassay of the serum gastrin level (IRG) within 60 minutes. The test was diagnosed as negative when the maximum increase of serum IRG was less than 80 pg/ml and also less than 20% of the basal serum IRG level. Three of the twelve patients underwent pancreatoduodenectomy (PD), and two patients underwent distal pancreatectomy. Extirpation of duodenal tumors with dissection of regional lymph nodes was performed in seven patients. In two of the seven patients the IOS test remained positive after extirpation of the duodenal tumors and the dissection of regional lymph nodes. In one patient PD was performed on the basis of the positive results, and the IOS test became negative after PD. In the other patient, two tiny metastatic liver tumors were identified and were resected, but the IOS test did not become negative. We closed the abdomen in 11 patients when we obtained negative results from the IOS test. The results of the IOS test were almost identical to the data obtained by the standard assay postoperatively. The serum IRG levels of all but one patient fell to the normal level, and the secretin test became negative postoperatively. The IOS test is thus useful and indispensable for curative resection of microgastrinomas in patients with ZES.  相似文献   
64.
PURPOSE: The purpose is to assess clinical significance of matrix metalloproteinase (MMP)-2 and MMP-9 status, especially MMP-2 status, in stromal cells in non-small-cell lung cancer (NSCLC) because experimental studies have revealed that stromal MMP-2 plays important roles in progression of malignant tumors, but most clinical studies focused on tumoral MMP-2 expression, not stromal MMP-2 expression. EXPERIMENTAL DESIGN: We conducted a retrospective study on MMP-2 and MMP-9 expression as evaluated immunohistochemically in a total of 218 consecutive patients with completely resected pathological stage I-IIIA, NSCLC. RESULTS: Strong MMP-2 expression in tumor cells and stromal fibroblasts were documented in 54 (24.8%) and 132 (60.6%) patients, respectively. Strong MMP-2 expression in stromal fibroblasts was more frequently seen in squamous cell carcinoma (72.7%) than in adenocarcinoma (54.9%; P = 0.016). Tumors showing strong MMP-2 expression in stromal fibroblasts showed a significantly higher intratumoral microvessel density (IMVD) than weak stromal MMP-2 tumors (mean intratumoral microvessel density, 50.9 versus 32.4, P = 0.003). In addition, postoperative prognosis of strong stromal MMP-2 patients was significantly poorer than that of weak stromal MMP-2 patients (5-year survival rate, 77.5 versus 60.2%, P = 0.032), and the prognostic significance was enhanced in squamous cell carcinoma patients but disappeared in adenocarcinoma patients. Multivariate analyses confirmed that strong stromal MMP-2 expression was a significant factor to predict a poor prognosis in squamous cell carcinoma patients, not in adenocarcinoma patients. In contrast, MMP-2 or MMP-9 status in tumor cells was not a significant prognostic factor. CONCLUSIONS: MMP-2 status in stromal fibroblasts, not in tumor cells, was a significant prognostic factor associated with angiogenesis in NSCLC.  相似文献   
65.
Although exfoliative dermatitis (erythroderma) secondary to malignancy is commonly associated with lymphomas or leukemias, coincident gastrointestinal (GI) malignancy and erythroderma is rare. The authors recently encountered a patient with gallbladder carcinoma presenting as erythroderma. A 77-yr-old Japanese man presented with a 3-mo history of erythematous eruptions with pruritus over almost the entire body. After confirming the diagnosis of erythroderma, asymptomatic gallbladder carcinoma was found. Further investigations detected no malignancies in other organs. An extended cholecystectomy was performed. Histologic examination of resected specimens revealed poorly differentiated adenocarcinoma with negative resection margins. The eruptions with pruritus resolved within 1 wk after the operation. This is the first report, to our knowledge, of coincident biliary malignancy and erythroderma. The experience of the current patient suggests that erythroderma secondary to GI malignancy may resolve spontaneously after curative resection of the tumor.  相似文献   
66.
The "glove" phenomenon is caused by arterial injection of a bone-imaging agent into the antecubital fossa. The authors describe a patient who incidentally received an arterial injection of bone-imaging agent into the right distal radial artery near the wrist, which resulted in a "hot" palm and thumb. The phenomenon of hot palm and thumb can be explained by normal anatomic-physiologic blood flow after radial artery injection. The radial artery contributes the blood supply to the thumb through the dorsal metacarpal arteries of the first metacarpals, and the dorsal carpal branch of the radial artery, a branch of the interosseous artery, and dorsal carpal branch of the ulnar artery form the dorsal carpal rete. The normal vascular anatomic-physiologic dynamic constituted the mixture and dilution effects after the distal radial artery injection that resulted in hot areas limited to the palm and thumb of the hand on bone scintigraphy.  相似文献   
67.
The effect of radiotherapy during immunotherapy on immune-related adverse events (irAEs) is not fully understood. We herein report a 74-year-old woman diagnosed with lung adenocarcinoma with programmed death ligand 1 expression ≥50% and treated with pembrolizumab. She developed fatal immune thrombocytopenia associated with pembrolizumab immediately following radiotherapy. A flow cytometry analysis of peripheral blood detected an increased expression of programmed death-1 (PD-1) and Ki-67 in CD4 and CD8 T cells after radiotherapy, compared with pre-irradiation measurements. This case suggests that radiotherapy may evoke irAEs during treatment with anti-PD-1 antibodies, which physicians should consider when using radiotherapy in patients treated with these drugs.  相似文献   
68.

Objectives

To examine the association between each type of frailty status and the incidence rate of depressive symptoms among community-dwelling older adults.

Design

Prospective cohort study.

Setting

General communities in Japan.

Participants

Participants comprised 3538 older Japanese adults.

Measurements

We assessed our participants in terms of frailty status (physical frailty, cognitive impairment, and social frailty), depressive symptoms (geriatric depression scale ≥6), and other covariates, and excluded those who showed evidence of depression. Then, after a 4-year interval, we again assessed the participants for depressive symptoms. Physical frailty was defined by the Fried criteria, showing 1 or more of these were physical frailty. To screen for cognitive impairment, receiving a score below an age-education adjusted reference threshold in 1 or more tests was cognitive impairment. Finally, social frailty was defined using 5 questions, and those who answered positively to 1 or more of these were considered to have social frailty.

Results

After multiple imputations, the incidence rate of depressive symptoms after 4 years of follow-up was 7.2%. The incidence rates of depressive symptoms for each frailty status were as follows: 9.6% for physical frailty vs 4.6% without, 9.3% for cognitive impairment vs 6.5% without, and 12.0% for social frailty vs 5.1% without. Finally, through the application of multivariable logistic regression analysis, the incidence of depressive symptoms was found to have a significant association with social frailty (odds ratio 1.55; 95% confidence interval 1.10–2.20) but not with physical frailty or cognitive impairment.

Conclusions

This study revealed that social frailty, in comparison with physical frailty and cognitive impairment, is more strongly associated with incidences of depressive symptoms among elderly.  相似文献   
69.

Background

The Pediatric Quality of Life Inventory? (PedsQL?) is a widely-used modular instrument for measuring health-related quality of life in children aged 2 to 18 years. The PedsQL? Brain Tumor Module is comprised of six scales: Cognitive Problems, Pain and Hurt, Movement and Balance, Procedural Anxiety, Nausea, and Worry. In the present study, we developed the Japanese version of the PedsQL? Brain Tumor Module and investigated its feasibility, reliability, and validity among Japanese children and their parents.

Methods

Translation equivalence and content validity were verified using the standard back-translation method and cognitive debriefing tests. Participants were recruited from 6 hospitals in Japan and the Children's Cancer Association of Japan, and questionnaires were completed by 137 children with brain tumors and 166 parents. Feasibility of the questionnaire was determined based on the amount of time required to complete the form and the percentage of missing values. Internal consistency was assessed using Cronbach's coefficient alpha. Test-retest reliability was assessed by retesting 22 children and 27 parents. Factorial validity was verified by exploratory factor analyses. Known-groups validity was described with regard to whole brain irradiation, developmental impairment, infratentorial tumors, paresis, and concurrent chemotherapy. Convergent and discriminant validity were determined using Generic Core Scales and State-Trait Anxiety Inventory for children.

Results

Internal consistency was relatively high for all scales (Cronbach's coefficient alpha > 0.70) except the Pain and Hurt scale for the child-report, and sufficient test-retest reliability was demonstrated for all scales (intraclass correlation coefficient = 0.45-0.95). Factorial validity was supported through exploratory factor analysis (factor-item correlation = 0.33-0.96 for children, 0.55-1.00 for parents). Evaluation of known-groups validity confirmed that the Cognitive Problems scale was sensitive for developmental impairment, the Movement and Balance scale for infratentorial tumors or paresis, and the Nausea scale for a patient currently undergoing chemotherapy. Convergent and discriminant validity with the PedsQL? Generic Core Scales and State-Trait Anxiety Inventory for children were acceptable.

Conclusions

The Japanese version of the PedsQL? Brain Tumor Module is suitable for assessing health-related quality of life in children with brain tumors in clinical trials and research studies.  相似文献   
70.
Vasospasm, initial neurological damage, rebleeding, and periprocedural complications are associated prognostic factors for clinical outcomes after aneurysmal subarachnoid hemorrhage (SAH). In this study, factors related to delayed ischemic neurological deficit (DIND) are evaluated using data from our institute for the last 18 years. Data from 2001 to 2018 of patients with aneurysmal SAH who underwent surgical clipping (SC) or endovascular coiling (EC) within 7 days of onset were retrospectively analyzed. Cases of mortality within 5 days after treatment were excluded. Multivariate analysis was used to identify the risk factors for DIND. In total, 840 cases of SAH were assessed; among these cases, 384 (45.7%) and 456 (54.3%) were treated with SC and EC, respectively. The frequency of DIND in the EC group was significantly less than that in the SC group (11.8% vs. 17.7%; p = 0.016). In the results of multivariate analysis, internal carotid artery (ICA) aneurysm and hemorrhagic complications were the risk factors for DIND. Cilostazol administration and EC were significant factors for vasospasm prevention after aneurysmal SAH (odds ratio of ICA aneurysm: 1.59, hemorrhagic complications: 1.76, SC: 1.51, and cilostazol administration: 0.51, respectively). Cilostazol administration was also a significant factor in patients who were treated with EC. ICA aneurysm, treatment strategy, hemorrhagic complications, and cilostazol administration were associated with DIND. Oral administration of cilostazol and avoiding hemorrhagic complications were effective in DIND prevention. If both treatments are available for ruptured aneurysms, clinicians should choose EC on the basis of its ability to prevent DIND.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号