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   1514篇
  免费   100篇
  国内免费   19篇
耳鼻咽喉   2篇
儿科学   41篇
妇产科学   38篇
基础医学   280篇
口腔科学   68篇
临床医学   154篇
内科学   299篇
皮肤病学   43篇
神经病学   85篇
特种医学   142篇
外科学   123篇
综合类   28篇
预防医学   73篇
眼科学   16篇
药学   103篇
中国医学   15篇
肿瘤学   123篇
  2023年   2篇
  2022年   6篇
  2021年   23篇
  2020年   13篇
  2019年   26篇
  2018年   34篇
  2017年   17篇
  2016年   31篇
  2015年   37篇
  2014年   37篇
  2013年   77篇
  2012年   78篇
  2011年   81篇
  2010年   58篇
  2009年   62篇
  2008年   66篇
  2007年   80篇
  2006年   68篇
  2005年   77篇
  2004年   50篇
  2003年   53篇
  2002年   49篇
  2001年   56篇
  2000年   52篇
  1999年   34篇
  1998年   54篇
  1997年   52篇
  1996年   33篇
  1995年   37篇
  1994年   19篇
  1993年   17篇
  1992年   26篇
  1991年   25篇
  1990年   28篇
  1989年   22篇
  1988年   26篇
  1987年   22篇
  1986年   15篇
  1985年   12篇
  1984年   12篇
  1983年   10篇
  1982年   6篇
  1981年   7篇
  1980年   10篇
  1979年   6篇
  1977年   4篇
  1976年   5篇
  1975年   9篇
  1974年   3篇
  1970年   2篇
排序方式: 共有1633条查询结果,搜索用时 31 毫秒
101.
Chang KC  Su IJ  Tsai ST  Shieh DB  Jin YT 《Oncology》2002,63(4):362-369
Betel quid (BQ) chewing has been a well-documented cause of oral epithelial lesions (OEL). Evolution from early hyperplastic lesions to the late or carcinomatous stage has been recognized. The pathobiological and molecular mechanism, however, remains to be elucidated. In this study, a total of 232 samples obtained from 153 cases of BQ-related OEL were retrospectively evaluated for the expression of p53 and bcl-2 in comparison with 26 cases of BQ-unrelated lesions (n = 29). The possible role of human papillomavirus (HPV) was also investigated. These BQ-related OELs included verrucous hyperplasia (VIH, n = 57, 24.6%), epithelial dysplasia (n = 23, 9.9%), verrucous carcinoma (VC, n = 5, 2.1%) and squamous cell carcinoma (SCC, n = 106, 45.7%). Fifty-four cases (35.3%) had multiple lesions. In comparison with the BQ-unrelated OELs, the characteristics of BQ-related OELs were a younger age, male predilection and multicentricity. In contrast to the tongue in BQ-unrelated OELs, the most common site for all types of BQ-related lesions was the buccal mucosa. Immunohistochemical studies of BQ-related lesions showed p53 staining in 30% of dysplasia and 38% of SCC, but a consistent absence in VH and VC. The cases with p53-positive SCC had a higher recurrence rate than p53-negative ones. Bcl-2 expression was negligible for all types of lesions. HPV-6/11 was detectable in 10% of dysplasia and 13% of SCC, but in neither VH nor VC. HPV-16/18, however, was consistently negative for all types of lesions. Our data suggest that p53, but not bcl-2, may play a role in tumor progression of BQ-related OELs, and that VH and VC are distinct and closely related histological lesions. The consistent absence of the malignant-type HPV in all BQ-related lesions suggests that HPV plays an insignificant role in the tumorigenesis of BQ-related oral cancers, although a cooperative role may exist between the benign-type HPV and BQ chewing.  相似文献   
102.
Asperger's Syndrome(AS) is a severe developmental disorder characterized primarily by marked and sustained difficulties in social interaction and unusual patterns of circumscribed interests and behavioral peculiarities. AS differs from autism primarily in that there is no general delay or retardation in language. A 3. 5 year-old boy with AS was referred for psychological assessment and treatment. When the boy was 23 months old, he was assessed with Bayley Scales of Infant Development (2nd ed.). Both MDI and PDI were within normal limits. After the referral, this boy was assessed with WPPSI-R and then prescribed 5 weekly intervention sessions consisting of communication skills training. At a one week's follow-up the boy was reassessed with Leiter-R. The results of WPPSI-R and Leiter-R showed the boy was in the normal intelligence range. From the second session to the fifth session, the boy's mother recorded 526 of his utterances. According to the analysis of these speech data, the language development for this boy was at Stage V, which indicated that his language development was in the superior range for his age. After 5 intervention sessions, the improvements in the child's communication skills were such that no further sessions were warranted. This boy might represent a case of aberrant neurofunctional organization. He has defects in perceptual organization but has good pattern recognition, which is based on features. It is theorized that his excellent verbal ability competed with the perceptual organization, so that he compensated for perceptual organization with verbal ability. An intervention designed to inhibit verbal compensation and facilitate configural processing is recommended.  相似文献   
103.
104.
5-Fluorouracil in combination with leucovorin has been shown to be active in therapeutic trials of metastatic colorectal carcinoma. In this study, we administered these drugs to 72 patients with metastatic colorectal carcinoma. Thirty-six of them without previous exposure to 5-fluorouracil were treated with weekly bolus injections of 5-fluorouracil (425 mg/m2) and leucovorin (25 mg/m2) supplemented with oral levamisole. Another 36 patients with or without prior 5-fluorouracil treatment received 5-fluorouracil 3,000 mg/m2 and leucovorin 300 mg/m2 in a 48-hour continuous infusion every two weeks. Clinical efficacy and toxicity were assessed by WHO criteria. Variables were tested for relations to response and survival by univariate and multivariate analysis. The response rate was 19.4% in weekly bolus arm and 13.9% in biweekly high-dose infusion arm (P = 0.527). Median survivals in the two arms were 18.4 months (weekly) and 21 months (biweekly) respectively (P = 0.708). Gastrointestinal side effects including nausea, vomiting, diarrhea and mucositia were the major toxicities of these regimens. By multivariate analysis, the only factor to influence response rate was the site of metastases (P = 0.009). The only factor to affect survival was performance status of the patient (P = 0.0001). We concluded that the two 5-fluorouracil based regimens are well-tolerated and shown to have a response rate comparable with previous reports of similar regimens in patients with metastatic colorectal cancer. Only liver metastases seemed to have a better response to therapy. Performance status is the most important prognostic factor in patients with metastatic colorectal cancer.   相似文献   
105.
A 28-year-old woman was admitted to our Hospital with a chief complaint of progressive gingival swelling and loosening of teeth over about a year. According to past history, she had received total thyroidectomy 2 years previously due to thyromegaly. The thyroidectomy specimen was at first interpreted as 'poorly differentiated carcinoma of the thyroid'. One year ago, she began to be aware of gingival swelling and loosening of teeth. A gum biopsy was taken and the pathologic features were similar to her 'thyroid carcinoma'. Subsequent investigations, including immunohistochemical stain, showed the gum was heavily infiltrated with histiocyte-like Langerhans' cells which were positive for S-100 protein. Ultrastructural examination of the cells under electron microscope revealed many typical intra-cytoplasmic Birbeck granules. Langerhans' cell histiocytosis was diagnosed. Langerhans' cell histiocytosis with thyroid involvement is extremely rare and may run a relatively indolent course. Even on a retrospective examination, it may easily be confused with poorly differentiated carcinoma of the thyroid. We suspect that this error may have been made on other occasions and that the occurrence of this condition may be underreported.   相似文献   
106.
The benefits of achieving a long term event free survival of 60-70% by using increasingly intense treatment regimens must be weighed against the increased risk of treatment toxicity. From 1985 to 1990, 1612 children with childhood acute lymphoblastic leukaemia (ALL) in the UK were treated on MRC UKALL X with intensive induction therapy, central nervous system directed therapy (cranial irradiation and intrathecal methotrexate), and continuing treatment for two years. There was a randomisation to receive blocks of additional intensification treatment at five weeks, 20 weeks, not at all, or both. The five year disease free survival was 71% for children randomised to two blocks of intensification, a 14% improvement on children randomised to no intensification treatment. Treatment related mortality in this national multicentre study has been analysed for induction and first remission (including those after intensification treatment). There were 38 induction deaths, 2.3% and 53 deaths in first remission, 3.3% (including those from a second malignancy). Thirty one (84%) of the induction deaths followed an infection: bacterial in 22 and fungal in nine. Thirty seven infective remission deaths occurred: bacterial in 11, viral in 16, fungal in seven, and three caused by Pneumocystis carinii pneumonia. Ten of these deaths followed a block of intensification treatment. The majority of noninfective remission deaths followed the development of a second tumour. Risk analysis for an induction death showed girls and children with Down's syndrome to be at greater risk. For deaths in first remission analysis showed an increased risk for bone marrow transplant (BMT) patients and children with Down's syndrome. There was no effect of age and leucocyte count for either group. Most significantly when BMT patients were excluded from the analysis, intensification treatment did not increase the risk of remission death.  相似文献   
107.
The present study revealed the efferent projections from the external cuneate nucleus (ECN) to various medullary nuclei in the gerbl as demonstrated in fresh living brainstem slices by using in vitro anterogradely tracing with the dextran-tetramethyl-rhodamine-biotin. The tracer-labelled ECN axon terminals were observed (1) in most of the vital autonomic-related nuclei: the nucleus solitary tractus, nucleus ambiguus, rostroventrolateral reticular nucleus and C2 adrenergic area, (2) in the reticular formation: the medullary, parvocellular, intermediate, gigantocellular, dorsal paragigantocellular and lateral paragigantocellular reticular nuclei and medullary linear nucleus, and (3) in sensory nuclei: the cuneate nucleus, spinal trigeminal nuclei caudalis and interpolaris, paratrigeminal nucleus, medial and spinal vestibular nuclei, inferior olive and prepositus hypoglossal nucleus. These new findings are discussed in relation to possible roles of the ECN in cardiovascular, respiratory and sensorimotor controls.  相似文献   
108.
Roxatidine acetate, a new H2 receptor antagonist, was compared with ranitidine in the treatment of duodenal ulcers in a double-blind multicentre study. Eighty-four patients with endoscopically proven duodenal ulcer were randomized to receive 150 mg roxatidine acetate or 300 mg ranitidine at bedtime. Repeat endoscopy was performed after 4 weeks (25–33 days) and if the ulcer had not healed, another endoscopy was performed after a further 4 weeks of treatment. Using per protocol analysis 73.6% of ulcers treated with roxatidine healed at 4 weeks compared to 72.2% of ulcers treated with ranitidine (P=NS). The healing rates at 8 weeks were 92% with roxatidine and 83.3% with ranitidine (P=NS). Using equivalence tests, the healing rate of roxatidine was found to be equivalent to that of ranitidine within a 20% region. Roxatidine users took significantly less antacids than ranitidine users (P < 0.05). There were no significant adverse effects due to roxatidine or ranitidine. Roxatidine is a safe effective drug in the treatment of duodenal ulcers with a healing rate comparable to that of ranitidine.  相似文献   
109.
110.
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