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   7364篇
  免费   346篇
  国内免费   36篇
耳鼻咽喉   106篇
儿科学   175篇
妇产科学   98篇
基础医学   977篇
口腔科学   144篇
临床医学   403篇
内科学   1712篇
皮肤病学   229篇
神经病学   575篇
特种医学   282篇
外科学   1246篇
综合类   40篇
一般理论   1篇
预防医学   211篇
眼科学   299篇
药学   328篇
中国医学   12篇
肿瘤学   908篇
  2023年   26篇
  2022年   58篇
  2021年   128篇
  2020年   79篇
  2019年   96篇
  2018年   130篇
  2017年   106篇
  2016年   164篇
  2015年   189篇
  2014年   191篇
  2013年   299篇
  2012年   424篇
  2011年   489篇
  2010年   291篇
  2009年   222篇
  2008年   441篇
  2007年   450篇
  2006年   493篇
  2005年   483篇
  2004年   498篇
  2003年   499篇
  2002年   456篇
  2001年   95篇
  2000年   85篇
  1999年   104篇
  1998年   124篇
  1997年   115篇
  1996年   94篇
  1995年   86篇
  1994年   68篇
  1993年   58篇
  1992年   62篇
  1991年   60篇
  1990年   37篇
  1989年   51篇
  1988年   44篇
  1987年   41篇
  1986年   48篇
  1985年   38篇
  1984年   38篇
  1983年   37篇
  1982年   28篇
  1981年   31篇
  1980年   24篇
  1979年   23篇
  1978年   24篇
  1977年   11篇
  1975年   13篇
  1973年   10篇
  1971年   10篇
排序方式: 共有7746条查询结果,搜索用时 265 毫秒
1.
2.
3.
4.
The aim of this study was to clarify and compare the temporal course of bone mineral density (BMD) between fast bone losers and normal residents in Miyama Village, a rural Japanese community. BMD was measured over a 10-year period in a cohort study in Miyama Village, Wakayama Prefecture, Japan, to provide information on rate of bone loss in the mature and elderly population. Subjects (n=400) were selected by sex and age stratum from the full list of residents born in 1910–1949, with 50 men and 50 women in each age decade. Baseline BMD of the lumbar spine and proximal femur was measured using dual energy X-ray absorptiometry in 1990, 1993, 1997 and 2000. In the cohort, 171 men and 189 women completed the follow-up survey performed in 1993. After calculating the rate of bone loss between 1990 and 1993, the greatest tertile from the distribution of bone loss was categorized as fast bone losers, with the remainder considered as normal subjects. Changes in BMD were compared between normal subjects and fast bone losers over the 10-year period. Mean rate of change for BMD at both lumbar spine and femoral neck in fast bone losers recovered to levels similar to those in normal subjects over 7 years of observation. By contrast, BMD at the lumbar spine and femoral neck decreased steeply over the 10-year period in both groups, and mean BMD for fast bone losers was significantly lower than that of normal subjects (P<0.05). These differences were apparent only at the lumbar spine in both men and women, even after adjusting for age. These results indicate that fast bone loss is a transient phenomenon rather than a fixed status, although individuals who have been categorized as fast bone losers at some stage continue to display low BMD in the lumbar spine.  相似文献   
5.
OBJECTIVE: To assess the functional results, health-related quality of life (QOL) outcomes, and complications in patients with an ileal neobladder in comparison to those with cutaneous diversion (ileal conduit and cutaneostomy). METHODS: Between September 1992 and February 2003, we consecutively performed an ileal neobladder (the Studer method) in 30 patients and cutaneous diversion in 38 patients. In August 2004, questionnaires were mailed to 54 patients. The questionnaire included the validated health-related quality of life (QOL) questionnaire, SF-36 General Health Survey, and a urinary incontinence questionnaire. We also evaluated the functional results in patients with an ileal neobladder and the postoperative complications in patients with both urinary diversions. RESULTS: The data from 41 patients (21 ileal neobladder procedures and 20 cutaneous diversions) were available for the analysis. No differences in the overall QOL were observed between the two groups. Complete daytime and night-time urinary continence was achieved in the 21 patients (100%) and 13 patients (61.9%), respectively. The mean value of the maximum flow rate was 15 +/- 12 mL/min in the 21 neobladder patients. There were 19 early complications in 18 patients (60.0%) and seven late complications in six patients (20.0%) with an ileal neobladder. However, there were 15 early complications in 14 patients (36.8%) and eight late complications in six patients (15.8%) with cutaneous diversions. CONCLUSION: The findings regarding the health-related QOL and the frequency of complications in the neobladder group and those in the cutaneous diversion group were similar. However, the functional results and the status of urinary continence in the neobladder patients were satisfactory.  相似文献   
6.
OBJECTIVE: Although hypercalciuria, a well-established adverse effect of vitamin D3, can be a risk factor of renal stone formation, the risk of nephrolithiasis has not been well defined. The consumption of a diet high in acid precursors is often cited as a risk factor for the development of calcium-based kidney stones. In the present study, we investigated the effect of chronic acid ingestion on kidney stone formation in rats treated with calcitriol (1-25[OH]2 D3). METHODS: Control rats (C-C), calcitriol-treated rats (C-V; three treatments of 0.5 microg of calcitriol per week) and acid-ingested (water containing 0.21 mol/L NH4Cl), calcitriol-treated (three treatments of 0.5 microg of calcitriol per week) rats (A-V) were fed in metabolic cages. After 1 month, urine, blood, kidney and bone samples were analyzed. RESULTS: The A-V rats exhibited elevated serum calcium concentrations, urinary calcium and phosphate excretion, urinary type I collagen cross-linked N-peptide (NTx)/creatinine values, mRNA expression of osteopontin in the kidney, and renal calcium contents as well as decreased bone mineral densities, compared with the C-C and C-V rats. Urinary citrate excretion was lower and NaDC-1 mRNA expression in the kidney was higher in the A-V rats than in the C-C and C-V rats. Calcium phosphate kidney stones were found in the A-V rats. CONCLUSIONS: The ingestion of NH4Cl, an acid precursor, promotes calcium phosphate kidney stone formation in calcitriol-treated rats. The chronic intake of a diet rich in acid precursors may be a risk factor for the development of kidney stones in subjects who are being treated with calcitriol.  相似文献   
7.
Although the prevalence of a learned voiding dysfunction and non-neurogenic neurogenic bladder (NNB), which is one type of dysfunctional elimination syndrome, is considered to be relatively rare, the association of NNB with Down syndrome (DS) has been elucidated in male patients. We herein describe the occurrence of NNB in an adult female with DS. The diagnosis was confirmed after completely ruling out any neurological or anatomical anomalies that could be related to a lower urinary tract dysfunction. She had renal dysfunction and multiple obstructive uropathies for which clean intermittent catheterization was successfully introduced.  相似文献   
8.
Abstract: Prevention of hyperacute rejection is a difficult and unsolved problem in xenotransplantation. Natural antibodies and complement activation have been known to play an important role in the xenotransplantation between discordant species pairs. In the present study, total blood exchange (TBE) was performed with pyridox-alated-hemoglobin-polyoxyethylene conjugate (PHP) solution (Ajinomoto Co., Inc., Kawasaki, Japan) before cardiac xenotransplantation in order to remove the immunoglobulins and prolong xenograft survival time. Guinea pigs and rats were used as the discordant species combination for donor and recipient. Two groups were established: Group 1, untreated control (n = 8) and Group 2, TBT with PHP solution (n = 8). The exchange blood transfusion was carried out at the rate of 15–20 ml/h utilizing PHP solution using a blood pump. After the blood exchange was processed, hematocrit (Ht) levels dropped to 4 or 5%, and a cardiac xenotransplantation was performed within 24 h. The levels of serum IgA, IgM, and IgG were decreased to less than 25, 25, and 10% of the base line, respectively, after blood exchange. A mean xenograft survival time in Group 2 was prolonged to 472 ± 74 min and to 10.4 ± 1.8 min in Group 1 (p < 0.01). A titer of the anti-guinea pig lymphocytotoxic antibody in rat serum was decreased to almost nil. The data from this study suggest that total blood exchange with PHP solution may be useful in preoperative removal of xenograft antibodies in xenotransplantation.  相似文献   
9.
Increased procollagen III production in patients with kidney disease   总被引:1,自引:0,他引:1  
Measurements of elevated procollagen III peptide (PIIIP) levels are used to monitor fibrosing activity in hepatic and various other diseases. Elevated PIIIP levels have also been reported in renal failure patients without such diseases. Therefore, the serum levels and renal clearance of PIIIP were investigated in 17 healthy volunteers and 100 patients with different types of acute (n = 15) and chronic (n = 85) kidney disease. PIIIP was measured by conventional and Fab radioimmunoassays. Median PIIIP levels in serum (18, range 5-55 ng/ml) and urine (34, range 1-110 micrograms/day) were significantly higher in kidney patients than serum (9, range 6-14 ng/ml) and urine levels (17, range 6-24 micrograms/day) in normal volunteers (p = 0.01). No significant differences (Kruskal-Wallis H test) were found, however, within the different kidney disease groups (acute, chronic/glomerulonephritis, interstitial nephritis). Median renal clearance of PIIIP-related peptides in kidney patients (1.5, range 0.5-2.4 ml/min) did not differ significantly (Wilcoxon U test) from that in normal volunteers (1.3, range 0.4-2.2 ml/min). These findings indicate that PIIIP elimination does not depend on renal function. PIIIP-related peptides in serum and urine, however, increase with renal failure irrespective of the activity or type of renal disease. This can be explained most probably by enhanced turnover of collagen type III by the affected kidney itself.  相似文献   
10.
Gliomatosis cerebri with good prognosis   总被引:4,自引:0,他引:4  
A 52-year-old man was admitted to our clinic with severe headache and bilateral papilledema. Magnetic resonance (MR) images on admission demonstrated diffuse swelling of the cerebral cortex without formation of a tumor mass. Biopsy revealed diffuse infiltration with neoplastic glial cells. After radiation and chemotherapy, the MR images returned to normal. The morphological and neurological features of the present case met the criteria for gliomatosis cerebri. However, this patient showed an unusually good response to radiation and chemotherapy.  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