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   5683篇
  免费   320篇
  国内免费   36篇
耳鼻咽喉   94篇
儿科学   50篇
妇产科学   76篇
基础医学   788篇
口腔科学   269篇
临床医学   375篇
内科学   1753篇
皮肤病学   176篇
神经病学   272篇
特种医学   144篇
外科学   835篇
综合类   24篇
预防医学   162篇
眼科学   81篇
药学   307篇
中国医学   5篇
肿瘤学   628篇
  2023年   52篇
  2022年   95篇
  2021年   158篇
  2020年   74篇
  2019年   90篇
  2018年   121篇
  2017年   97篇
  2016年   112篇
  2015年   119篇
  2014年   131篇
  2013年   199篇
  2012年   374篇
  2011年   370篇
  2010年   206篇
  2009年   181篇
  2008年   310篇
  2007年   319篇
  2006年   315篇
  2005年   347篇
  2004年   332篇
  2003年   278篇
  2002年   308篇
  2001年   117篇
  2000年   106篇
  1999年   114篇
  1998年   74篇
  1997年   69篇
  1996年   47篇
  1995年   43篇
  1994年   25篇
  1993年   27篇
  1992年   68篇
  1991年   62篇
  1990年   51篇
  1989年   67篇
  1988年   67篇
  1987年   51篇
  1986年   65篇
  1985年   53篇
  1984年   50篇
  1983年   41篇
  1982年   17篇
  1979年   26篇
  1978年   15篇
  1977年   15篇
  1974年   15篇
  1972年   20篇
  1970年   18篇
  1969年   20篇
  1968年   17篇
排序方式: 共有6039条查询结果,搜索用时 618 毫秒
991.
BACKGROUND: There is not a well established method for further screening of asymptomatic microhematuria found through annual health examinations. However, it is apparent that a large number of examiners are using ultrasonography for screening. When slight hydronephrosis is found through screening, it is difficult to determine whether further examinations, such as intravenous pyelography (IVP), should be performed. In this paper, we discuss the usefulness of post-voiding repeated renal ultrasonography, which was applied to 57 patients with slight hydronephrosis found in a screening. METHODS: Ultrasonography in the kidney and the urinary bladder at the ultrasound laboratory of Toma Hospital was carried out on a total of 1906 patients with asymptomatic microhematuria, which was found by routine annual health examination, from January 1996 to December 1998. Slight hydronephrosis was found in 57 (14 males and 43 females) of 1906 patients and post-voiding repeated renal ultrasonography was carried out on all patients. RESULTS: Slight hydronephrosis had disappeared and IVP was avoided in 22 (38.6%) of 57 patients. Of 35 cases in which slight hydronephrosis persisted after urination, there were no abnormalities on IVP in 32 patients, while abnormalities were found in three patients. Two of these had ureteropelvic junction stenosis and the remaining one had a ureteral stone. CONCLUSION: The results of this study indicate that post-voiding repeated renal ultrasonography is useful for avoiding unnecessary further examination to determine whether upper urinary tract obstruction exists, when slight hydronephrosis is observed upon screening by simultaneous renal and urinary bladder ultrasonography for asymptomatic microhematuria.  相似文献   
992.
Objective Visceral larva migrans (VLM) caused by Ascaris suum is a major health problem in pig farming regions. The clinical characteristics of pulmonary VLM caused by A. suum, however, are unclear. We assessed the clinico-radiologic features of this disease. Methods Medical records, including the results of chest radiography and high-resolution computed tomography (HRCT), were retrospectively reviewed from January 2000 through June 2019, at the University of Miyazaki Hospital and Kyoritsuiin Hospital in Miyazaki Prefecture, Japan. Results Seven patients with VLM caused by A. suum were identified. All seven patients had a unique habit of consuming raw foods, such as organic vegetables, chicken, turkey, wild boar, and venison. All but one patient, who had eosinophilic pneumonia with a fever and severe fatigue, had only mild or no respiratory symptoms. All 7 patients had remarkable eosinophilia (median, 1,960 /μL) and high serum IgE levels (median, 1,346 IU/mL). Chest HRCT revealed multiple nodules and multiple nodular ground-glass opacities in 57% and 29% of the patients, respectively. The pulmonary lesions were located predominantly in subpleural areas. All seven patients were treated with albendazole, which led to improvement within two to three months. Neither eggs nor parasites were detected in the feces or sputum of any patient. Conclusion Consumption of raw organic vegetables or raw meat is a possible route of A. suum infection. Infected patients exhibit mild respiratory symptoms, and multiple nodules with a halo in the subpleural area are a common finding on chest HRCT. Treatment with albendazole was effective in these cases.  相似文献   
993.
BackgroundMassive blood transfusion compensating hemorrhage during lung transplantation (LT) results in primary graft dysfunction (PGD) and worse outcomes after LT. Collateral vessels in the perihilar mediastinal pleura could be the source of hemorrhage during LT in patients with pulmonary hypertension (PH). The purpose of this study was to examine the effect of closure with hemoclips of the vessels in the perihilar mediastinal pleura on the risk of intraoperative hemorrhage and outcomes after LT in patients with PH.MethodsWe retrospectively reviewed 80 patients who underwent LT, including 13 patients with primary PH, 29 patients with secondary PH, and 38 patients with non-PH.ResultsThe median number of hemoclips was significantly higher in the primary PH group than in the non-PH group (P=0.0045) or secondary PH group (P=0.0060). The intraoperative blood loss, transfusion volume, maximum PGD grade, and the 30-day and 90-day mortality rates in the primary PH group were equivalent to those in the other two groups.ConclusionsMeticulous closure of collateral vessels in the perihilar mediastinal pleura during LT in patients with primary PH allowed intraoperative hemorrhage to be controlled and might be associated with acceptable mortality rate in these patients similar to that of LT in patients with other diseases.  相似文献   
994.
995.
The authors aimed to impart the apatite-forming ability to 50 wt% carbon fiber-polyetheretherketone composite (50C-PEEK), which has more suitable mechanical properties as artificial bone materials than pure PEEK. First, the 50C-PEEK was treated with sulfuric acid in a short time to form pores on the surface. Second, the surface of the 50C-PEEK was treated with oxygen plasma to improve the hydrophilicity. Finally, fine particles of calcium phosphate, which the authors refer to as “apatite nuclei”, were precipitated on the surface of the 50C-PEEK by soaking in an aqueous solution containing multiple inorganic ions such as phosphate and calcium (modified-SBF) at pH 8.20, 25 °C. The 50C-PEEK without the modified-SBF treatment did not show the formation of apatitic phase even after immersion in simulated body fluid (SBF) for 7 days. The 50C-PEEK treated with the modified-SBF showed the formation of apatitic phase on the entire surface within 1 day in the SBF. The apatite nuclei-precipitated 50C-PEEK will be expected as a new artificial bone material with high bioactivity that is obtained without complicated fabrication processes.  相似文献   
996.
Background: Chronic limb-threatening ischemia (CLTI) is the most advanced stage of peripheral artery disease. Therefore, a multidisciplinary approach is necessary to avoid major amputation in CLTI patients. Malnutrition worsens the condition of CLTI patients, and therefore, it may be important to evaluate the nutritional status in patients with CLTI. This study was designed to evaluate the baseline patient characteristics and the influence of the controlling nutritional status (CONUT) score on the clinical results. Method and Results: A retrospective, single-center, non-randomized study was conducted to evaluate the associations of death, major amputation, and wound healing rate at 12 months with the CONUT score on admission. Consecutive CLTI patients (mean age 73.2 ± 10.4 years; 84 males) who underwent endovascular therapy (EVT) for infra-popliteal lesions at Fukuoka University Hospital from January 2014 to May 2019 were enrolled and divided into two groups (higher and lower CONUT score groups). The higher CONUT group showed a higher percentage of dialysis (66.7% vs. 33.9%, p < 0.001) and a higher clinical frailty scale (5.9 ± 1.4 vs. 4.9 ± 1.9, p = 0.005) than the lower CONUT group. Rates of amputation-free survival were 89.5% and 69.8% in the lower and higher CONUT groups, respectively. In addition, rates of wound healing at 12 months were 98.0% and 78.3% in the lower and higher CONUT groups, respectively. Multivariate regression analysis demonstrated that a higher CONUT score was an independent predictor for delayed wound healing (OR: 11.2; 95% CI: 1.29–97.5; p = 0.028). Conclusion: An assessment of the nutritional status using the CONUT score could be useful for predicting wound healing, and earlier nutritional intervention may improve the outcome of CLTI patients. Early examination and treatment, along with raising awareness of the issue, may be important for improving the prognosis.  相似文献   
997.
Renal cell carcinoma (RCC) represents 2% of all diagnosed malignancies worldwide, with disease recurrence affecting 20% to 40% of patients. Existing prognostic recurrence models based on clinicopathological features continue to be a subject of controversy. In this meta-analysis, we summarized research findings that explored the correlation between clinicopathological characteristics and post-surgery survival outcomes in non-metastatic RCC patients. Our analysis incorporates 99 publications spanning 140 568 patients. The study's main findings indicate that the following clinicopathological characteristics were associated with unfavorable survival outcomes: T stage, tumor grade, tumor size, lymph node involvement, tumor necrosis, sarcomatoid features, positive surgical margins (PSM), lymphovascular invasion (LVI), early recurrence, constitutional symptoms, poor performance status (PS), low hemoglobin level, high body-mass index (BMI), diabetes mellitus (DM) and hypertension. All of which emerged as predictors for poor recurrence-free survival (RFS) and cancer-specific survival. Clear cell (CC) subtype, urinary collecting system invasion (UCSI), capsular penetration, perinephric fat invasion, renal vein invasion (RVI) and increased C-reactive protein (CRP) were all associated with poor RFS. In contrast, age, sex, tumor laterality, nephrectomy type and approach had no impact on survival outcomes. As part of an additional analysis, we attempted to assess the association between these characteristics and late recurrences (relapses occurring more than 5 years after surgery). Nevertheless, we did not find any prediction capabilities for late disease recurrences among any of the features examined. Our findings highlight the prognostic significance of various clinicopathological characteristics potentially aiding in the identification of high-risk RCC patients and enhancing the development of more precise prediction models.  相似文献   
998.
Hypoxia is a common feature of solid tumors. However, the impact of hypoxia on immune cells within tumor environments remains underexplored. Carbonic anhydrase 9 (CA9) is a hypoxia-responsive tumor-associated enzyme. We previously noted that regardless of human CA9 (hCA9) expression, hCA9-expressing mouse renal cell carcinoma RENCA (RENCA/hCA9) presented as a “cold” tumor in syngeneic aged mice. This study delves into the mechanisms behind this observation. Gene microarray analyses showed that RENCA/hCA9 cells exhibited elevated mouse serpinB9, an inhibitor of granzyme B, relative to RENCA cells. Corroborating this, RENCA/hCA9 cells displayed heightened resistance to antigen-specific cytotoxic T cells compared with RENCA cells. Notably, siRNA-mediated serpinB9 knockdown reclaimed this sensitivity. In vivo tests showed that serpinB9 inhibitor administration slowed RENCA tumor growth, but this effect was reduced in RENCA/hCA9 tumors, even with adjunctive immune checkpoint blockade therapy. Further, inducing hypoxia or introducing the mouse CA9 gene upregulated serpinB9 expression, and siRNA-mediated knockdown of the mouse CA9 gene inhibited the hypoxia-induced induction of serpinB9 in the original RENCA cells. Supernatants from RENCA/hCA9 cultures had lower pH than those from RENCA, suggesting acidosis. This acidity enhanced serpinB9 expression and T cell apoptosis. Moreover, coculturing with RENCA/hCA9 cells more actively prompted T cell apoptosis than with RENCA cells. Collectively, these findings suggest hypoxia-associated CA9 not only boosts serpinB9 in cancer cells but also synergistically intensifies T cell apoptosis via acidosis, characterizing RENCA/hCA9 tumors as “cold.”  相似文献   
999.
To assess the risk of major birth defects after first-trimester exposure to carbocisteine and ambroxol during pregnancy, we conducted a prospective cohort study using counseling data for drug use during pregnancy provided by the Japan Drug Information Institute in Pregnancy and Toranomon Hospital. Counseling information, including drug usage and participants' demographic information, was collected between April 1988 and December 2017. Pregnancy outcome data, including major birth defects, were obtained using a questionnaire administered 1 month after delivery. The risks of major birth defects after first-trimester exposure to carbocisteine (n = 588) and ambroxol (n = 341) were compared with those of nonteratogenic drug use during the first trimester (n = 1525). The adjusted odds ratio (aORs) for major birth defects was calculated using a multiple logistic regression analysis adjusted for confounders. The incidence of major birth defects was 1.2% (7/588) and 2.1% (7/341) in the carbocisteine and ambroxol groups, respectively, which was comparable to the control group (26/1525, 1.7%). Results of multiple logistic regression demonstrated similar nonsignificant risks for both carbocisteine (aOR: 0.66, 95% confidence interval [CI]: 0.40–1.1, p = 0.11) and ambroxol (aOR: 1.1, 95% CI: 0.18–7.2, p = 0.88). No specific major birth defects were reported in the carbocisteine or ambroxol groups. This study demonstrated that carbocisteine and ambroxol exposure during the first trimester was not associated with an increased risk of major birth defects. These results could help in counseling for the use of these drugs during pregnancy and further alleviate anxiety in patients.  相似文献   
1000.
Comparative genomic hybridization (CGH) is a technique that allows the detection of losses and gains in DNA copy number across the entire genome. We used CGH to study the genetic alterations that occur in primary astrocytomas, including 14 glioblastomas (GBM), 12 anaplastic astrocytomas (AA), and 7 low-grade astrocytomas (LGA). The average numbers of total aberrations in GBM, AA, and LGA were 9.7, 5.4, and 4.0, respectively. The average number of DNA sequence losses in GBM was significantly higher than that in AA or LGA (P < 0.01). Frequently altered regions (> eight cases) observed in all grades of astrocytoma were 7p13-p12 (gain), 7q31 (gain), 8q24.1-q24.2 (gain), 9p21 (loss), 10p12-p11 (loss), 10q22-qter (loss), 13q21-q22 (loss), and 20q13.1-q13.2 (gain). Loss of 9p, 10p, or 10q, and the gain or amplification of 7p, were observed frequently in GBM (64%, 57%, 64%, and 50% of cases, respectively). Frequent alterations found in AA were losses of 9p, 10q, and 13q, and gains of 1q, chromosome 7, 11q, and Xq. Whereas 7p13-p11 amplification occurred exclusively in cases with the loss of all or part of chromosome 10, this change never occurred in cases having an increase in copy number of 8q, which was the most frequent change observed in LGA (four of seven cases). These results may indicate that an increase in copy number of 8q is an important event in GBM, with a genetic pathway, which is distinct from that in GBM with 7p amplification. Genes Chromosomes Cancer 21:340–346, 1998. © 1998 Wiley-Liss, Inc.  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