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   28644篇
  免费   1552篇
  国内免费   260篇
耳鼻咽喉   262篇
儿科学   561篇
妇产科学   641篇
基础医学   2905篇
口腔科学   668篇
临床医学   2054篇
内科学   8160篇
皮肤病学   359篇
神经病学   2482篇
特种医学   1129篇
外科学   5263篇
综合类   55篇
一般理论   6篇
预防医学   1137篇
眼科学   531篇
药学   1684篇
中国医学   59篇
肿瘤学   2500篇
  2024年   33篇
  2023年   293篇
  2022年   612篇
  2021年   1037篇
  2020年   586篇
  2019年   841篇
  2018年   1014篇
  2017年   735篇
  2016年   886篇
  2015年   906篇
  2014年   1233篇
  2013年   1518篇
  2012年   2316篇
  2011年   2201篇
  2010年   1273篇
  2009年   1227篇
  2008年   1905篇
  2007年   1832篇
  2006年   1719篇
  2005年   1720篇
  2004年   1616篇
  2003年   1377篇
  2002年   1248篇
  2001年   148篇
  2000年   149篇
  1999年   184篇
  1998年   216篇
  1997年   171篇
  1996年   163篇
  1995年   155篇
  1994年   130篇
  1993年   115篇
  1992年   103篇
  1991年   70篇
  1990年   79篇
  1989年   61篇
  1988年   51篇
  1987年   46篇
  1986年   58篇
  1985年   52篇
  1984年   40篇
  1983年   38篇
  1982年   54篇
  1981年   33篇
  1980年   29篇
  1979年   20篇
  1978年   16篇
  1976年   16篇
  1975年   11篇
  1974年   17篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
41.
Cancer of the penis is a rare neoplasm in developed countries but worldwide represents a significant health problem. In this study, the ultrasonographic features of primary and secondary malignant lesions of the penis are described. Squamous cell carcinoma usually presents as a hypoechoic lesion with heterogeneous appearance. Invasions of the corpora cavernosa and the corpus spongiosum are appreciable. B-cell lymphoma presents as a well-vascularized mass, a plaque, or ulcers in the penile skin. Penile metastases result from hematogenous or lymphatic spreading of distant tumors or, more frequently, as penile infiltration by tumors from adjacent organs. Diffuse corporeal or nodular involvement can result. 1Award-winning poster at the 10th European Symposium on Urogenital Radiology; Uppsala, Sweden, September 4•7, 2003.  相似文献   
42.
43.
The purpose of this study was to evaluate the ability of helical computed tomography (CT) to detect arterial injuries in gunshot wounds to the neck. In a blinded retrospective review, 54 helical CT scans of the cervical spine were evaluated for bullet/bone fragments, subcutaneous air, bullet path, hematoma, spine fractures, and pharyngoesophageal compromise. The distance of fragments to a major vessel was calculated. CT findings that correlated significantly with major arterial injury included the presence of fragments (bullet/bone) close to a major vessel (2.5 mm) and spine fractures. Visualizing fragments <5 mm from a vessel or a transcervical bullet trajectory predicted 12 of 13 major arterial injuries. We conclude that CT clearly depicts anatomic damage. Specific findings, such as the location of fragments and bullet trajectory adjacent to a vessel and spine fractures, indicate a higher probability of vascular damage, thus directing more definitive evaluation.  相似文献   
44.
The clinical and biochemical presentation of carcinoma of the pancreas (PC) and of the papilla of Vater (CPV) are very similar, and, consequently, detailed investigations are required to correctly distinguish between them. The aim of the present study was to select the clinical and biochemical variables that would most efficiently discriminate the precise site of tumor origin. The study group consisted of 72 patients with PC and 22 patients with CPV consecutively hospitalized in our department. The following clinical parameters were considered: age, asthenia, anorexia, vomiting, weight loss, pain, fever, pruritis, and constipation; the biochemical parameters considered were total, direct, and indirect bilirubin, glucose, alkaline phosphatase, gamma glutamy transferase, transaminase, total protein, amylase, and occult blood in stools. The results indicated that in the initial phase of PC the most frequent clinical parameters were weight loss (P<0.0001), anorexia (P<0.02), constipation (P<0.001), and pruritus (P<0.01). In contrast, in CPV, fever (P<0.003) was most frequent in the same phase. There was a statistically significant difference in occult blood in stools (P<0.0001), total (P<0.03) and direct bilirubin (P<0.02), alkaline phosphatase (P<0.05), and transaminase (P<0.002) values in the two groups. On discriminant analysis, weight loss, constipation, pruritus, nausea, anorexia, and fever were the variables which best discriminated between the two types of tumors. In fact, the presence of weight loss, anorexia, asthenia, constipation, and pruritus correctly classified 87.5% of the patients with PC, while the presence of fever and nausea correctly classified 72.7% of the patients with CPV.  相似文献   
45.
The purpose of this study was threefold: to evaluate the role of gallium-67 scintigraphy in the staging of low-grade non-Hodgkin’s lymphomas (LGNHL), to assess the relationship between the expression of CD71 on the surface of the neoplastic cells and the 67Ga uptake by the tumour, and to establish the contribution of 67Ga scan in defining the prognosis of LGNHL. Forty-eight patients with untreated LGNHL diagnosed in a single institution over a decade were reviewed. The end point of the study was survival of the patients according to the scintigraphic 67Ga score at diagnosis. In addition to 67Ga scan, other prognostic variables were studied, relating to the neoplastic burden, the biology of the tumour and the host. Univariate and multivariate analyses were used. 67Ga scan identified only 116/286 (41%) nodes involved by lymphoma that were detected by clinical examination or computed tomography scan. A scintigraphic scoring system with an arbitrary cut-off value of 3 (high scan score) was able to predict patients with a dismal prognosis: with a mean follow-up of 47 months (range: 1–146 months) the median survival time was 28 months in patients with a high scan score and 74 months in patients with a low scan score (P=0.002). CD71 values were 27.4%±14.9% (mean ±SD) in the former and 8.9%±7.2% in the latter (P=0.0001). Only performance status and extranodal sites were significant variables for prognosis in multivariate analysis. It is concluded that 67Ga scan is inaccurate in staging but might be very important in defining the prognosis in LGNHL, in association with other prognostic variables. Received 1 May and in revised form 6 August 1997  相似文献   
46.
47.
Available results highlight the lack of good level of evidence studies on the pure prognostic value of histological grade. In the present study, the prognostic relevance of histological grade and of its three components, tubule formation, nuclear pleomorphism and mitotic count, was analyzed in a series of 372 patients with node-negative breast cancer treated with locoregional therapy alone until early relapse. Histological grade was determined blindly by two observers and discordance between evaluations was resolved after joint review using a multihead microscope. No relation was observed between histological grade and any of its three components and disease-free survival. Conversely, a significant relation was observed between histological grade and distant metastasis-free survival (at 6 years, 94, 86 and 76% for grades 1, 2 and 3, respectively, P=0.013) as well as overall survival (98, 90 and 86%, P=0.001). A breakdown analysis as a function of the three components showed that neither tubule formation nor nuclear pleomorphism was associated with prognosis, and only mitotic count strongly influenced both distant metastasis-free survival (91, 82 and 74%, P=0.014) and overall survival (97, 87 and 85%, P=0.011). Histological grade suffers from a much higher subjectivity than any other microscopic evaluation of biomarkers as it is the sum of three different morphological features. Within the Italian Network for Quality Assessment of Tumor Biomarkers program we observed that histological grade is an independent prognostic variable, but also that this role is ascribable only to the number of mitotic figures. In conclusion, due to the ever smaller size of diagnosed breast cancers, resulting in less cancer tissue for biofunctional and molecular analysis, mitotic count evaluated under strict quality control conditions seems to be an accurate and feasible prognostic variable.  相似文献   
48.
49.
50.
The results of the first 3 year' collaboration of the Italian Registry of Paediatric Chronic Peritoneal Dialysis (CPD) (1986–1988) are presented. This Registry acquired data on the majority of the paediatric patients treated with CPD in Italy, thus providing a national picture in a field where few nationwide surveys are available. Patients of less than 15 years of age at the start of dialysis were enrolled and clinical data collected until the age of 19 years. The number of nephrological paediatric centres participating in the Registry increased from 7 in 1986 to 11 in 1988. The total number of patients on CPD was 70 and the percentage of dialysed children treated with CPD ranged from 40.2% to 43.6%. Data on 89 peritoneal catheters were collected: during 1417 dialysis-months 70 catheter-related complications were observed (1:20.8 dialysis-months); actuarial catheter survival was 92.7% at 6 months, 84.8% at 1 year and 68.8% at 2 years. The incidence of peritonitis changed from 1 episode every 10.9 patient-months in 1986 to 1 every 19.8 in 1988. Abdominal hernias were the other main clinical complication observed. The survival of patients was 92.5% at 3 years, while the technique survival at the same time was 84%.  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