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   51360篇
  免费   3978篇
  国内免费   1677篇
耳鼻咽喉   431篇
儿科学   1457篇
妇产科学   508篇
基础医学   6479篇
口腔科学   2234篇
临床医学   4246篇
内科学   6299篇
皮肤病学   441篇
神经病学   1565篇
特种医学   3190篇
外国民族医学   11篇
外科学   15293篇
综合类   6316篇
现状与发展   2篇
一般理论   1篇
预防医学   1343篇
眼科学   194篇
药学   1966篇
  20篇
中国医学   1024篇
肿瘤学   3995篇
  2024年   67篇
  2023年   585篇
  2022年   1156篇
  2021年   1464篇
  2020年   1430篇
  2019年   1335篇
  2018年   1580篇
  2017年   1368篇
  2016年   1674篇
  2015年   1778篇
  2014年   3032篇
  2013年   3248篇
  2012年   2475篇
  2011年   2859篇
  2010年   2518篇
  2009年   2710篇
  2008年   2626篇
  2007年   2735篇
  2006年   2563篇
  2005年   2567篇
  2004年   2148篇
  2003年   1804篇
  2002年   1462篇
  2001年   1227篇
  2000年   1169篇
  1999年   998篇
  1998年   838篇
  1997年   838篇
  1996年   765篇
  1995年   683篇
  1994年   637篇
  1993年   483篇
  1992年   469篇
  1991年   426篇
  1990年   355篇
  1989年   302篇
  1988年   293篇
  1987年   246篇
  1986年   243篇
  1985年   279篇
  1984年   210篇
  1983年   131篇
  1982年   181篇
  1981年   160篇
  1980年   147篇
  1979年   161篇
  1978年   140篇
  1977年   122篇
  1976年   79篇
  1973年   48篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
The diagnostic usefulness of sentinel lymph node biopsy (SLNB) has been well established, but its therapeutic value remains unproven. First introduced by Morton and colleagues, the SLNB procedure is now widely available, and markedly enhances our ability to pathologically stage the regional nodes. Although the SLN status is acknowledged as the most powerful indicator of prognosis in melanoma, there is no evidence to-date, of survival advantage for complete lymphadenectomy in SLN-positive patients. Also, there is no effective adjuvant therapy that could benefit these sentinel node-positive patients, as yet. Additionally, new data have emerged indicating a possible increase in local/in-transit recurrence following complete lymphadenectomy in sentinel node-positive patients. To understand fully and to evaluate these observations we need information from randomized controlled trials. Major changes have occurred following the latest revision of melanoma staging system (AJCC, 6th edition). Concerning N category, these include the incorporation of the number of metastatic lymph nodes, the tumour burden of nodal metastases, and the ulceration of the primary tumour. The data obtained from the new staging system will reflect differences in prognosis that were not previously emphasized and which, we hope, will serve as a guide to more accurate analysis of metastatic pathways in cutaneous melanoma as well as a rationale for new forms of treatment.  相似文献   
992.
目的探讨火把花根片在小鼠骨髓移植模型中减轻急性移植物抗宿主病(acute graft-versus-host disease,aGVHD)的效果及可能的作用机制。方法建立小鼠异基因骨髓移植GVHD模型,预处理为放疗8.0Gy,分为:对照组(n=10)异基因骨髓细胞(2×10~6)加脾T淋巴细胞(2×10~6)移植组;火把花根片组(n=20)异基因骨髓细胞(2×10~6)加脾T淋巴细胞(2×10~6)移植加火把花根片预防组。比较受鼠生存时间和GVHD发生情况,受鼠外周血象中白细胞、血球压积等恢复情况和骨髓细胞中嵌合体H-2D~b阳性细胞百分比以评价造血重建。在移植后不同时间点分别采用流式细胞仪检测受鼠的脾细胞中CD4~+和CD8~+以及CD25和CD69的表达。结果移植后对照组受鼠均于25天内死于GVHD,火把花根片组GVHD的发生率为20%(4/20),与对照组小鼠相比,存活率和时间明显增高和延长(P<0.01);存活的火把花根片组小鼠(n=4)40天时骨髓细胞中的H-2D~b阳性细胞百分比达(93.38±4.32)%。移植后10天开始,火把花根片组小鼠CD4~+和CD8~+T细胞比例明显低于对照组(P<0....  相似文献   
993.
The clinical manifestations of chronic disseminated histoplasmosis are non-specific and resemble those of other chronic infections and malignancies. We report the radiographic, sonographic and contrast-enhanced CT appearances of histoplasmosis in an adult male with non-insulin dependent diabetes mellitus, who was HIV negative and presented with weight loss and pyrexia. Imaging studies simulated tuberculosis with mediastinal lymphadenopathy, bilateral fibrotic lung lesions, hepatomegaly and bilateral hypoattenuating adrenal enlargement, without clinical or laboratory evidence of hypoadrenalism. Computed tomography-guided fine-needle aspiration biopsy of adrenal glands revealed Histoplasma capsulatum. We report our experience to increase awareness of the imaging spectrum of disseminated histoplasmosis and its similarity to tuberculosis as, with increasing incidence of AIDS, the chances of these infections are likely to increase. Moreover, awareness of this entity is important because it is known that untreated disseminated histoplasmosis is fatal.  相似文献   
994.
89锶内照射治疗转移性骨肿瘤骨痛的临床观察   总被引:2,自引:0,他引:2  
目的:分析89锶治疗转移性骨肿瘤的临床疗效及其安全性.方法:42例转移性骨肿瘤患者接受了89锶治疗.治疗后定期测定血常规、血生化等指标,随访时间3个月以上.对患者骨痛缓解情况、不良反应和血液学、肝肾功能变化进行观察和评价.结果:42例中有效35例,总有效率83.3%,起效时间2~20 d,缓解持续时间3~14个月.毒性反应主要有轻度可逆性骨髓抑制,血液学毒性小于Ⅱ级.无过敏反应及其他特殊不良反应.对肝肾功能无明显影响.结论:89锶对于转移性骨肿瘤所致的剧烈疼痛有良好的止痛效果,毒副作用小,是提高患者的生存质量的一种有效、安全的治疗方法.  相似文献   
995.
目的比较急、慢性粒细胞白血病初诊骨髓磁共振成像(MRI)表现。方法搜集经细胞形态学、免疫学及遗传学(MIC)分型综合分析确诊的成人初诊急性粒细胞白血病28例及慢性粒细胞白血病16例,所有患者均行骨盆及股骨中上段MRI检查,选取20名年龄匹配的健康志愿者作为对照组。结果将患者骨髓MRI表现按浸润程度和范围分为5级,急性粒细胞白血病患者23例属Ⅰ~Ⅲ级,5例属Ⅳ级,无Ⅴ级病例;慢性粒细胞白血病患者12例属Ⅴ级,4例属Ⅳ级,无Ⅰ~Ⅲ级病例。两组患者MRI分级总体分布差异具有统计学意义(Uc=5.231,P<0.01)。结论慢性粒细胞白血病初诊患者骨髓MRI多显示弥漫浸润,急性粒细胞白血病患者股骨头及大转子可保持正常信号,前者受累范围大于后者。  相似文献   
996.
Objective: Alendronate and calcitonin are antiresorptive drugs that were used for the treatment of postmenopausal osteoporosis and were shown to increase bone mineral density (BMD). However, the effect of both drugs in daily clinical practice may differ from that observed in clinical trials.Method: About 50 postmenopausal osteoporotic women were observed during their first year of treatment. Among them, 32 patients used alendronate and 18 used calcitonin. Lumbar spine and femoral neck BMD were measured by dual energy X-ray absorptiometry (DXA) at baseline and after 1 year of therapy. Biochemical markers (B-ALP – bone-specific alkaline phosphatase, OTC – osteocalcin and DPD/UCr – deoxypyridinoline/creatinine ratio) of bone metabolism were measured at baseline and 6 months later. Patient compliance was assumed by tablet counting and verified at interview. Each patient was further questioned about her attitude towards the treatment, as well as her dairy product intake, physical activity, use of other medications, smoking and social status.Main outcome measure: (1) Annual percent change in BMD in lumbar spine and femoral neck after the one-year treatment with either alendronate or calcitonin. (2) The change in biochemical markers of bone turnover.Results: The lumbar spine BMD significantly increased by 7.0% (P < 0.001), the femoral neck BMD by 4.3% (P < 0.01). OTC, B-ALP and DPD/UCr decreased significantly during the therapy with alendronate. Compliance with therapy was 79% (95% CI 68–90%). In the calcitonin-treated group, the lumbar spine BMD significantly increased by 3.1 % (P < 0.05), while the femoral neck BMD remained unchanged. OTC, B-ALP and DPD/UCr did not change significantly during the treatment with calcitonin. Compliance with calcitonin therapy was 87% (95% CI 63–110%). The annual change of BMD in both treatment groups was independent on all questioned factors.Conclusion: In daily practice, alendronate enhanced significantly BMD both in lumbar spine and femoral neck. Calcitonin showed increase only in the lumbar spine BMD.  相似文献   
997.
Objective. To investigate the frequency and morphology of extraosseous extension in patients with Gaucher disease type I. Design and patients. MRI examinations of the lower extremities were analyzed in 70 patients with Gaucher disease type I. Additionally, the thoracic spine and the midface were investigated on MRI in two patients. Results. Four cases are presented in which patients with Gaucher disease type I and severe skeletal involvement developed destruction or protrusion of the cortex with extraosseous extension into soft tissues. In one patient, Gaucher cell deposits destroyed the cortex of the mandible and extended into the masseter muscle. In the second patient, multiple paravertebral masses with localized destruction of the cortex were apparent in the thoracic spine. In the third and fourth patient, cortical destruction with extraosseous tissue extending into soft tissues was seen in the lower limbs. Conclusions. Extraosseous extension is a rare manifestation of Gaucher bone disease. While an increased risk of cancer, especially hematopoietic in origin, is known in patients with Gaucher disease, these extraosseous benign manifestations that may mimic malignant processes should be considered in the differential diagnosis of extraosseous extension into soft tissues. A narrow neck of tissue was apparent in all cases connecting bone and extraosseous extensions. Received: 19 July 1999 Revision requested: 8 September 1999 Revision received: 7 October 1999 Accepted: 14 October 1999  相似文献   
998.
男性原发性骨质疏松症中医证型的实质探讨   总被引:4,自引:2,他引:4  
目的:探讨男性原发性骨质疏松症中医证型的实质.方法:男性原发性骨质疏松症患者按中医临床辩证分型为肾阳虚型、肾阴虚型和非肾虚型.采用回归和判别分析法来研究骨密度、血清激素、血生化、血清微量元素、尿生化等指标与中医证型的相关性,探讨其中医证型的实质.结果:男性原发性骨质疏松症患者睾酮(T)、血清降钙素(CT)、铜(Cu)值显著降低;肾阴虚组、肾阳虚组骨钙素(BGP)值均显著高于对照组和非肾虚组;CT值于各组之间差别显著,其中非肾虚组CT值显著低于正常对照组,肾阴虚组、肾阳虚组CT值均非常显著低于对照组;甲状旁腺激素的羧基端片段(PTH-c)值于各组之间差别显著,肾阴虚组、肾阳虚组PTH-c值均非常显著低于对照组和非肾虚组,其中肾阳虚组还显著低于肾阴虚组;雌二醇(E2)值于各组差别显著,其中非肾虚组显著低于正常对照组,肾阴虚组、肾阳虚组非常显著低于对照组.结论:男性原发性骨质疏松症患者钙丢失、骨丢失明显加快,而骨形成并没有加快.肾虚与非肾虚划分的生化基础为T和尿钙/肌酐(Ca/Cr);男性原发性骨质疏松症的中医证型与骨代谢生化指标有密切相关,骨代谢生化指标的改变是辩证分型的基础.  相似文献   
999.
龙岩市中老年人群骨质疏松的流行病学调查   总被引:2,自引:0,他引:2  
目的:分析龙岩市中老年人群骨密度(BMD)及骨质疏松(OP)患病率变化规律,为骨质疏松预防提供科学依据.方法:随机对龙岩市40岁以上的人群进行BMD测定,受试者共176人,准确记录受试者性别、年龄,使用美国Lunar公司的DEXA测定L2~4及髋部的BMD,然后进行比较和统计分析.结果:男性的BMD以50岁组或60岁组最低;女性的BMD随年龄的增加而明显下降,但70岁组下降平缓;除了40岁组外,同龄组男性BMD大于女性BMD.男性各年龄组腰椎(L2~4)的骨质疏松症患病率均低于女性各组,且较女性迟10年.结论:女性在40岁以后应监测BMD的变化,男性在50岁以后应监测BMD的变化,60岁组应为男女性BMD监测的重点.龙岩市中老年人群应普及预防知识,加强锻炼,增加户外活动,以减少OP的发生.  相似文献   
1000.
目的探讨慢性髓系白血病(CML)细胞中Ph染色体阳性细胞与bcr/abl融合基因表达之间的关系及临床意义.方法用热变性姬姆萨R显带(RHG)技术和逆转录筑巢式聚合酶链反应(RT-nest-PCR)对171例CML患者的骨髓或外周血单个核细胞进行了分析,并对其中17例行异基因骨髓移植(Allo-BMT)患者进行短期随访.结果154例未经异基因造血干细胞移植(allo-PBSCT)的CML患者中142例(92.2%)为Ph染色体阳性,146例(94.8%)表达bcr/abl mRNA,2种方法结果一致者142份(92 2%).17例患者allo-BMT后1~24个月,仅1例出现Ph阳性,12月后RT-PCR分析结果10例阴性,7例阳性.结论2种方法各有其优缺点,在CML患者的诊断和治疗监测中,宜将细胞遗传学分析与PCR方法相结合.allo-BMT是目前治疗CML的最佳方法之一.  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