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   325242篇
  免费   29186篇
  国内免费   22928篇
耳鼻咽喉   2991篇
儿科学   3433篇
妇产科学   4930篇
基础医学   39995篇
口腔科学   5508篇
临床医学   45368篇
内科学   49899篇
皮肤病学   3088篇
神经病学   18377篇
特种医学   12012篇
外国民族医学   213篇
外科学   33289篇
综合类   50123篇
现状与发展   76篇
一般理论   20篇
预防医学   19820篇
眼科学   9574篇
药学   32932篇
  334篇
中国医学   17483篇
肿瘤学   27891篇
  2024年   1002篇
  2023年   5022篇
  2022年   13057篇
  2021年   16408篇
  2020年   12050篇
  2019年   10896篇
  2018年   11420篇
  2017年   9927篇
  2016年   9368篇
  2015年   14370篇
  2014年   17831篇
  2013年   15404篇
  2012年   22905篇
  2011年   25931篇
  2010年   16045篇
  2009年   12334篇
  2008年   17117篇
  2007年   17142篇
  2006年   17169篇
  2005年   16852篇
  2004年   10706篇
  2003年   9781篇
  2002年   8454篇
  2001年   7483篇
  2000年   8292篇
  1999年   9021篇
  1998年   5475篇
  1997年   5500篇
  1996年   4332篇
  1995年   3922篇
  1994年   3213篇
  1993年   2097篇
  1992年   2827篇
  1991年   2415篇
  1990年   2117篇
  1989年   1861篇
  1988年   1563篇
  1987年   1352篇
  1986年   1107篇
  1985年   912篇
  1984年   526篇
  1983年   373篇
  1982年   242篇
  1981年   238篇
  1980年   188篇
  1979年   221篇
  1978年   82篇
  1977年   89篇
  1974年   102篇
  1973年   83篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
BACKGROUND AND OBJECTIVE: Mucosa intact laser tonsillar ablation is an alternative to conventional tonsillectomy. The efficacy of this procedure was demonstrated in canines, but establishing the safety of irradiating human tonsils is paramount. STUDY DESIGN/MATERIALS AND METHODS: An optical-thermal simulation of tonsillar tissue irradiation was previously developed, but the effect of varying parameters was not investigated. The tissue response to irradiation at 5-25 watts for 1 minute and 10 watts for 10 seconds to 162 seconds is simulated. RESULTS: At 15 watts and greater, the peak temperature is over 100 degrees C and the mucosal temperature is over 70 degrees C. At the depth of the tonsil, the temperature does not vary significantly. The peak temperature is at 1 mm. The radial temperature profile is not significantly altered by longer irradiation times. CONCLUSIONS: The optimal dosimetry parameters for irradiation of human tonsillar tissue at 805 nm with the MILTA technique is under 15 watts for approximately 1 minute.  相似文献   
992.
强力天麻杜仲胶囊治疗高血压病肝阳上亢症疗效观察   总被引:3,自引:0,他引:3  
目的 :观察强力天麻杜仲胶囊治疗高血压病肝阳上亢症疗效。方法 :选取院门或住院高血压病肝阳上亢症患者 6 6例 ,随机分为治疗组 5例 ,对照组 31例。对照组给予洛汀新片 ,1 0 mg,每天一次口服 ,治疗组给予洛汀新片面性 1 0 mg,每天一次口服的同时 ,给予强力天麻杜仲胶囊口服 ,疗程 3周。观察血压、眩晕等症状改善情况 ,结果 :治疗组与对照组对上述指标均有改善作用 ,但治疗组改善明显优于对照组  相似文献   
993.
PURPOSE: Denileukin diftitox is a fusion protein combining diphtheria toxin and interleukin-2 (IL-2) that targets tumor cells expressing the IL-2 receptor. Its efficacy has been shown in CD25+ cutaneous T-cell lymphoma, but not in B-cell non-Hodgkin's lymphoma (NHL). A phase II study was performed to evaluate the efficacy and tolerability of denileukin diftitox for relapsed or refractory B-cell NHL. PATIENTS AND METHODS: Patients with relapsed or refractory B-cell NHL were eligible. Tumor CD25 expression was determined by immunohistochemistry or flow cytometry. Denileukin diftitox was administered intravenously at a dose of 18 microg/kg once daily for 5 days every 3 weeks, up to eight cycles. RESULTS: Of the 45 patients assessable for response, 32 (71%) were refractory to the last chemotherapy treatment, and all were previously treated with rituximab. Three complete responses (6.7%) and eight partial responses (17.8%) were observed, for an overall response rate of 24.5%. Nine patients (20%) had stable disease. Objective response rates were similar in CD25+ (22%) and CD25- histologies (29%), as were stable disease rates (22% and 18%, respectively). For responding patients, the median time to treatment failure was 7 months, with a median follow-up in survivors of 18 months (range, 9 to 28 months), and the projected progression-free survival at 20 months was 24% (95% CI, 0% to 60%). Most toxicities were low-grade and transient. CONCLUSION: Denileukin diftitox seems to be effective in relapsed or refractory, CD25+ and CD25- B-cell NHL and is well-tolerated at the dosage evaluated. Evaluation of denileukin diftitox in combination with other agents may be warranted.  相似文献   
994.
PURPOSE: This study was undertaken to determine whether low intratumoral doses of the epidermal growth factor receptor ligand-transforming growth factor alpha (TGF-alpha) fused to Pseudomonas exotoxin (TGF-alpha-PE38)-abrogated head and neck squamous cell carcinoma (HNSCC) tumor growth in vitro and in vivo. EXPERIMENTAL DESIGN: In vitro cytotoxicity assays were carried out to determine the sensitivity of HNSCC cells to TGF-alpha-PE38. TGF-alpha-PE38-treated HNSCC cells were examined by immunoblotting for cleaved poly(ADP-ribose) polymerase to evaluate apoptosis. Nude mice bearing established HNSCC xenografts were treated with several doses of TGF-alpha-PE38 to evaluate the antitumor efficacy in vivo. Tumor sections were stained with terminal deoxynucleotidyl transferase-mediated nick end labeling for apoptosis. To determine the effect of oral administration of TGF-alpha-PE38, gavage injections of TGF-alpha-PE38 were administered, and the esophagus and surrounding soft tissue were then stained for apoptotic cells. RESULTS: HNSCC cell lines examined were sensitive to low doses of TGF-alpha-PE38 (EC(50) in the range of 1.6 to 10 ng/mL). HNSCC cells treated with TGF-alpha-PE38 undergo apoptosis. Antitumor effects were observed using 0.1 and 0.03 microg of TGF-alpha-PE38 administered intratumorally. At these doses, the treatment was well tolerated. Tumors treated with the toxin had a higher number of apoptotic cells compared with the control tumors. No apoptotic cells were observed in the pharyngoesophageal tissues of the mice after gavage administration of the toxin suggesting that the toxin could be orally administered without toxicity. CONCLUSIONS: These results indicate that topical or intratumoral administration of low doses of TGF-alpha-PE38 may demonstrate antitumor effects in HNSCC without associated systemic toxicity.  相似文献   
995.
996.
结缔组织增生性小圆细胞肿瘤2例并文献复习   总被引:1,自引:0,他引:1  
目的:分析结缔组织增生性小圆细胞肿瘤(DSRCT)的临床病理特征。方法:结合文献对2例相对少见的DSRCT进行临床、病理形态及免疫组化研究。结果:DSRCT由成团巢的小圆细胞和丰富的结缔组织间质组成。免疫组化:小圆形的肿瘤细胞vimentin( );desmin( );EMA( );CK( );NSE( )。结论:DSRCT为高度侵袭性肿瘤,主要累及腹腔或盆腔的腹膜,肿瘤由小圆细胞和丰富的结缔组织间质组成。  相似文献   
997.
998.
Exposure of cells to heat inhibits a number of nuclear activities associated with semi-conservative replication of DNA including the incorporation of radiolabelled precursors into acid-insoluble DNA, the initiation of new replicons, the elongation of the DNA fibre at the replication fork, the synthesis and deposition of new histones into chromatin and the reorganization of nascent DNA into mature chromatin. These effects are likely to underlie the heat sensitivity of S-phase cells and may contribute to the radiosensitization observed in this phase of the cell cycle. While some of these effects may be explained as 'passive' consequences of heat-induced damage on chromatin structures experiments reviewed here point to the activation of a checkpoint as a contributing factor to the observed inhibition of DNA replication. Activation of a heat responsive S-phase checkpoint targets the activity of RPA via interaction with nucleolin. Nucleolin, a major nucleolar protein, is found normally sequestered in the nucleolus. Exposure of cells to heat causes a rapid translocation of nucleolin from the nucleolus into the nucleoplasm that enables RPA/nucleolin interaction. This interaction inhibits functions of RPA associated with the initiation of DNA replication and contributes to the immediate inhibition of DNA synthesis observed after heat shock. The results suggest that the nucleolus serves as a sequestration centre for the temporary inactivation of regulatory molecules, such as nucleolin, capable of regulating essential cellular functions after heat shock. It is speculated that this regulatory process is integrated in the network of responses that determine cell sensitivity to heat and that it may be involved in heat radiosensitization to killing as well.  相似文献   
999.
BACKGROUND: Renal cortical neoplasms have been reported after organ transplantation, but the level of risk as well as the histological features are poorly defined. METHODS: A retrospective autopsy-based study was performed to evaluate renal neoplasms occurring in patients who underwent solid organ transplantation, died, and received an autopsy from 1981 to 1997 (383 liver, 125 heart, 52 lung, 39 heart/lung, 98 kidney, 4 bowel). Patients were divided into those with short (less than 101 days), medium (101 days to 5 years), and long-term survival (more than 5 years). The control group consisted of hospital autopsies on nontransplanted patients from the odd-numbered years, 1983 through 1997. RESULTS: Renal cortical neoplasms were identified in 32/1325 of nontransplanted patients and 15/701 transplanted patients. In transplanted patients, neoplasms were identified in 14 native and 1 allograft kidney: 2/391 in short-term survivors, 3/234 in medium, and 10/76 in long term survivors. While transplant patients with short and medium length survival had no increased risk for neoplasms, patients with long-term survival showed a 9-fold increase in cortical neoplasms. Transplant patients with neoplasms averaged 47 years of age at death, significantly younger than the average age of 70 for nontransplanted control patients with renal neoplasms. The neoplasms in transplanted patients were all tubulopapillary, except for one clear cell neoplasm and ranged in size from 0.1 to 2 cm. CONCLUSIONS: Long-term survivors of solid organ transplants have an 9-fold increased risk of developing tubulopapillary renal cortical neoplasms.  相似文献   
1000.
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