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   5425篇
  免费   292篇
  国内免费   77篇
耳鼻咽喉   34篇
儿科学   120篇
妇产科学   69篇
基础医学   637篇
口腔科学   80篇
临床医学   655篇
内科学   1354篇
皮肤病学   111篇
神经病学   215篇
特种医学   309篇
外科学   617篇
综合类   322篇
预防医学   302篇
眼科学   64篇
药学   511篇
  3篇
中国医学   106篇
肿瘤学   285篇
  2022年   46篇
  2021年   80篇
  2020年   63篇
  2019年   50篇
  2018年   62篇
  2017年   69篇
  2016年   82篇
  2015年   84篇
  2014年   148篇
  2013年   152篇
  2012年   243篇
  2011年   247篇
  2010年   174篇
  2009年   164篇
  2008年   260篇
  2007年   256篇
  2006年   225篇
  2005年   198篇
  2004年   178篇
  2003年   163篇
  2002年   194篇
  2001年   208篇
  2000年   215篇
  1999年   196篇
  1998年   84篇
  1997年   79篇
  1996年   85篇
  1995年   73篇
  1994年   64篇
  1993年   68篇
  1992年   113篇
  1991年   100篇
  1990年   88篇
  1989年   99篇
  1988年   89篇
  1987年   85篇
  1986年   63篇
  1985年   79篇
  1984年   58篇
  1983年   41篇
  1981年   21篇
  1979年   25篇
  1977年   23篇
  1966年   22篇
  1959年   41篇
  1958年   66篇
  1957年   76篇
  1956年   75篇
  1955年   83篇
  1954年   52篇
排序方式: 共有5794条查询结果,搜索用时 15 毫秒
1.
2.
3.
OBJECTIVES: Lateral biopsies are thought to have a better cancer detection rate compared with standard sextant biopsies. This study aimed to determine whether lateral peripheral zone biopsies in Japanese men who underwent transrectal ultrasound-guided prostate biopsies provided a significantly higher cancer detection rate than sextant biopsies. METHODS: Between 1999 and 2004, data were collected from 461 men who underwent prostate biopsy and had enough data regarding the performance of lateral biopsies for statistical analysis. There were two categories in this study: (i) patients who underwent sextant prostate biopsies; and (ii) patients who underwent sextant biopsies plus lateral biopsies. RESULTS: Prostate cancer was detected in 141 (30.6%) of 461 patients. It was detected in 24 (22.2%) of 108 patients who underwent sextant biopsies and 117 (33.1%) of 353 patients who underwent sextant plus lateral biopsies. Lateral biopsies were not associated with a statistically higher rate of positive biopsy findings; however, we found a significantly higher ratio of patients with positive findings in those with prostate specific antigen (PSA) levels 10 ng/mL (one of 71, 1.4%) among those who had positive cores only in lateral biopsy samples (P < 0.0001). CONCLUSIONS: Lateral biopsies did not show a significantly higher detection ratio of prostate cancer compared to sextant biopsies. However, lateral biopsies were more effective than sextant biopsies in patients with lower PSA levels. Our findings might be useful for the establishment of biopsy strategies to detect prostate cancer, especially in patients with lower PSA levels.  相似文献   
4.
We have treated advanced transitional-cell carcinoma of the urothelial tract with methotrexate, vinblastine, Adriamycin, and cisplatin (M-VAC) chemotherapy since July of 1985. We analyzed the effect of that chemotherapy in 26 patients with advanced urothelial cancer who were treated in our hospital and followed up. They were divided into two groups. Group 1 consisted of 15 patients with distant metastases. In all, 11 of them received M-VAC as adjuvant chemotherapy for metastatic lesions after surgical removal of the primary lesion, and the remaining 4 patients were not operable since they had very advanced-stage tumors; they received only M-VAC chemotherapy. Group 2 contained 11 patients who received M-VAC neo-adjuvant chemotherapy. In group 1, the overall response rate was 57.1% and the mean duration of response was 12.6 months. In the 11 patients who had received M-VAC as adjuvant therapy after surgical removal of the primary tumor, the mean duration of response was 14.1 months. After M-VAC chemotherapy, six patients underwent surgical resection of metastatic lesions and restaging was done pathologically in these cases. The clinical response coincided with the pathological response in all six cases. In group 2,5 of 11 patients experienced histological downstaging of the resected bladder. M-VAC chemotherapy combined with surgical resection of residual tumors has proved to be an effective option against advanced urothelial cancer.Presented at the 4th International Conference on Treatment of Urinary Tract Tumors with Adriamycin/Farmorubicin, 16–17 November 1990, Osaka, Japan  相似文献   
5.
Traumatic degeneration of myelinated fibers was studied by electron microscopy over 5 days following transection of mouse sciatic nerve. Special attention was paid to the mechanism which separates the degenerating part, while preserving the viable part of the axon. Immediately after transection, the opened end of the proximal stump revealed extensive subcellular changes including the disorganization of neurofilaments, and disruption of mitochondria and axonal endoplasmic reticulum (SER). Subsequently, vesicles of round and tubular profiles filled up the whole area of the stump end, and proximal to it appeared a neurofilament-predominant area characterized by randomly oriented neurofilaments and normally appearing mitochondria and SER. Characteristic membranous demarcations occurred in early periods at the border between the vesicle accumulation and the neurofilament-predominant areas, and later also within these areas. The demarcation membranes formed both by invagination of the surface plasma membrane and, probably, by fusion of the large vesicles. These became prominent with time, dividing the axoplasm into compartments of varying sizes, which gradually underwent degeneration and were liberated from the parent axon. Occurrence of autophagic vacuoles was characteristic of the degenerating portions of the parent axon. Thus, by the function of demarcation membranes, the parent axon to be preserved could remain membrane-bound, while the degenerating parts were shed off.  相似文献   
6.
In order to clarify age-related changes in kidneys, the renal function and histological changes were evaluated in 962 patients with mild mesangial proliferative glomerulonephritis (Mes PGN) whose ages ranged from 7 to 82 years. The glomerular filtration rate (GFR) (Ccr), renal plasma flow (RPF) (CPAH) and PSP excretion rate were significantly lower in nephritic patients than in normal subjects. Age-related decreases of GFR, RPF, PSP excretion rate and maximal urine specific gravity in Fishberg concentration test were found in both groups. Serum levels of creatinine, urea nitrogen and uric acid were significantly higher in nephritic patients than in the normal population. Age-related increases of those parameters were found in both groups. The incidence of sclerotic glomeruli was almost same as that of the normal population estimated by Kaplan et al. The incidence of arterio- and arteriolosclerosis was also higher than that of normal subjects estimated by Bell. Thus, arterio- and arteriolosclerosis seems to be more age-dependent than glomerulosclerosis in patients with mild Mes PGN. In conclusion, renal functions decrease and renal arteriolar lesions increase gradually in proportion to aging. Mes PGN, even mild, can accelerate the physiological age-related decrease of renal function.  相似文献   
7.
Uncertainties remain as to whether breastfeeding is protective against childhood allergic disorders. Positive relationships of breastfeeding with asthma and atopic eczema were observed in two previous Japanese studies. This cross-sectional study investigated the association between the feeding pattern after birth and the prevalence of allergic disorders during the past 12 months in Japanese schoolchildren. Study subjects were 24,077 children aged 6-15 yr in Okinawa. The outcomes were based on diagnostic criteria from the International Study of Asthma and Allergies in Childhood. Allowance was made for age, sex, number of siblings, smoking in the household, paternal and maternal history of asthma, atopic eczema, and allergic rhinitis, and paternal and maternal educational level. Breastfeeding, regardless of exclusivity, for 13 months or longer and exclusive breastfeeding for 4-11 months were independently associated with a higher prevalence of atopic eczema, particularly among children without a parental allergic history. A clear positive dose-response relationship was observed between prolonged duration of breastfeeding, regardless of exclusivity, but not exclusive breastfeeding, and the prevalence of atopic eczema. We found a significant positive trend for atopic eczema across the three categories (formula milk, partial and exclusive breastfeeding) in the first 4 months of life although the odds ratio for exclusive breastfeeding was not statistically significant. No material association was found between the feeding pattern after birth and the prevalence of wheeze or allergic rhinoconjunctivitis. Prolonged breastfeeding may be associated with a higher prevalence of atopic eczema in Japanese children.  相似文献   
8.
Patients on long-term hemodialysis (HD) are known to develop amyloid osteoarthropathy, evidenced as cystic radiolucencies on X-rays of the affected joints. To study the relationship between cystic radiolucencies and amyloid osteoarthropathy in 394 patients, we classified the severity of the cystic radiolucencies seen in the wrist joint on a 4-point scale and evaluated the association between lesion severity (grade) and several parameters. Biopsy was performed in 8 patients with 11 bone cysts of the wrist joint who had been operated for carpal tunnel syndrome. HD for 10 years or longer, age 50 or older and the presence of carpal tunnel syndrome were associated with severe cyst rating. There was no association between lesion grade and serum level of PTH-C, aluminum or beta 2-microglobulin (B2M). Ten of the 11 biopsied bone cysts in 8 patients with carpal tunnel syndrome demonstrated amyloid deposits which reacted with B2M. We conclude that a cystic radiolucency observed in the wrist joint of a patient undergoing HD indicates the deposition of amyloid. The cyst grade provides a useful marker for the severity of amyloid osteoarthropathy in HD patients.  相似文献   
9.
Measurement of serum haptoglobin by immunoturbidimetry was markedly interfered with hemolysis because of haptoglobin-hemoglobin complex formation. Turbidity formed with haptoglobin and immunoglobulin complexes was gradually decreased by the addition of hemoglobin in the reaction mixture, and reached to a certain fixed levels when serum haptoglobin were saturated with hemoglobin. The turbidity derived from saturated haptoglobin and hemoglobin complex closely correlated with the haptoglobin level without hemoglobin. Thus, we could measure the corrected haptoglobin level in hemolytic specimen by the saturation of hemoglobin in reaction mixture.  相似文献   
10.
The thymoma-prone rat of the BUF/Mna strain is a useful model for human thymoma. In this strain thymoma development is regulated by a single autosomal susceptible gene, Tsr-1. At pre-thymoma age, BUF/Mna rats have extremely large thyrauses, when compared to those of other strains of rats. Genetic studies in crosses between BUF/Mna rats with large thymuses and WKY/NCrj rats with small thymuses suggested the presence of a major autosomal gene, Ten-1 , which contributes to thymus enlargement in a backcross population. Linkage studies between Ten-1 and microsatellite markers in backcross rats of (WKY/NCrj×BUF/Mna)Fl×BUF/Mna have led to the localization of Ten-1 in chromosome 1. This result may provide an approach to clone Tsr-1 , which could be allelic to Ten-1.  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