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   55389篇
  免费   4760篇
  国内免费   2626篇
耳鼻咽喉   912篇
儿科学   1181篇
妇产科学   353篇
基础医学   7660篇
口腔科学   8241篇
临床医学   4558篇
内科学   5473篇
皮肤病学   561篇
神经病学   1732篇
特种医学   2332篇
外国民族医学   24篇
外科学   10644篇
综合类   8161篇
现状与发展   8篇
预防医学   1773篇
眼科学   606篇
药学   3394篇
  29篇
中国医学   1948篇
肿瘤学   3185篇
  2024年   127篇
  2023年   829篇
  2022年   1508篇
  2021年   2141篇
  2020年   2083篇
  2019年   1885篇
  2018年   1770篇
  2017年   1891篇
  2016年   1863篇
  2015年   2201篇
  2014年   3424篇
  2013年   4716篇
  2012年   2926篇
  2011年   3466篇
  2010年   3013篇
  2009年   2853篇
  2008年   2818篇
  2007年   2812篇
  2006年   2560篇
  2005年   2387篇
  2004年   2154篇
  2003年   1899篇
  2002年   1543篇
  2001年   1325篇
  2000年   1054篇
  1999年   968篇
  1998年   814篇
  1997年   771篇
  1996年   716篇
  1995年   522篇
  1994年   515篇
  1993年   386篇
  1992年   375篇
  1991年   306篇
  1990年   258篇
  1989年   240篇
  1988年   194篇
  1987年   157篇
  1986年   138篇
  1985年   181篇
  1984年   140篇
  1983年   115篇
  1982年   132篇
  1981年   96篇
  1980年   94篇
  1979年   91篇
  1978年   98篇
  1977年   65篇
  1976年   62篇
  1975年   37篇
排序方式: 共有10000条查询结果,搜索用时 46 毫秒
21.
Statin, a HMG-CoA reductase inhibitor, was shown to increase BMP-2 gene expression for bone formation, by blocking the mevalonate pathway in cholesterol production. We investigated the effect of naringin, a flavonoid available commonly in citrus fruits, which was also a HMG-CoA reductase inhibitor, in UMR 106 osteoblastic cell line in vitro. The control group consisted of cells cultured without any intervention for different time intervals (24 h, 48 h, and 72 h), whereas the experimental (naringin) group consisted of cells cultured with naringin of different concentrations (0.001 micromol/L, 0.01 micromol/L, and 0.1 micromol/L) for the same time intervals of the control. Colorimetric Tetrazolium (MTT) assay, total protein content assay, and alkaline phosphatase activity were used to measure the cellular activities. Results for the naringin group showed an increase in MTT assay compared with the control and the effect was dose dependent. At high concentration (0.1 micromol), the increases ranged from 60% to 80%. In the total protein content assay, naringin also showed an increase compared with control and the effect was also dose dependent. At high concentration (0.1 micromol), the increases ranged from 9% to 20%. In the alkaline phosphatase activity assay, naringin at high concentration (0.1 micromol) significantly increased the activity up to 20%. In conclusion, naringin significantly increased bone cell activities in vitro. This is the first study specifically attempted to investigate the effect of naringin on bone cell activities. Besides statin, this provided another example of mevalonate pathway blockage in the cholesterol production pathway by HMG-CoA reductase inhibition will increase the bone cell activities.  相似文献   
22.
The light microscopic and polarization appearances of calcium pyrophosphate dihydrate crystal deposits in tissues are reviewed. In routine sections haematoxylinophilic crystalline deposits with a feathery or brush-like pattern are typical of calcium pyrophosphate dihydrate. Short rhomboidal crystals showing positive birefringence are seen on polarization; X-ray microanalytical and infrared spectroscopic data support the specificity of these appearances. The appearances of the crystal deposits in decalcified specimens are also described. We include six cases of calcium pyrophosphate dihydrate deposition within periarticular bone; to the best of our knowledge this has not previously been described.  相似文献   
23.
Smoking delays the healing process and increases morbidity associated with many common musculoskeletal disorders, including long bone fracture. In the current study, a murine model of tibial fracture healing was used to test the hypothesis that smoking delays chondrogenesis after fracture. Mice were divided into two groups, a nonsmoking control group and a group exposed to cigarette smoke for 1 month prior to surgical tibial fracture. Mice were euthanized at 7, 14, and 28 days after surgery. The outcomes measured were immunohistochemical staining for type II collagen protein expression as a marker of cartilage matrix and proliferating cell nuclear antigen (PCNA) staining to measure proliferation at the site of injury. Toluidine blue staining and histomorphometry were used to quantify areas of cartilaginous and noncartilaginous fracture callus. Radiographs were analyzed for evidence of remodeling after injury. At day 7 after injury, mice exposed to cigarette smoke had a smaller fracture callus with less cartilage matrix compared to controls. Proliferation was present at high levels in both groups at this time point, but proliferating cells had a more immature morphology in the smoking group. At day 14, chondrogenesis was more active in smokers compared to controls, while a higher percentage of bone was present in the control animals. At day 28, X-ray analysis revealed a larger fracture callus remaining in the smoking animals. Together, these findings show that the chondrogenic phase of tibial fracture healing is delayed by smoking. This study represents, to our knowledge, the first analysis of molecular and cellular mechanisms of healing in a smoking mouse fracture model.  相似文献   
24.
25.
In this study the distribution patterns of various extracellular matrix components and their receptors (i.e. β1 integrins) in B-cell non-Hodgkin lymphomas were examined and compared to those in reactive lymphoid tissue. Neoplastic follicles within follicular lymphomas showed similar patterns to that observed in reactive follicles, which appeared to be strongly associated with the presence of follicular dendritic cells. Diffuse lymphomas of low and intermediate malignancy grade revealed features comparable to those of interfollicular areas of reactive lymphoid tissue, irrespective to which compartment the tumour cells were related. Highly malignant lymphomas, however, displayed unique extracellular matrix configurations, resulting from active matrix degradation by macrophages; this may support rapid tumour growth. Extranodal lymphomas showed virtually the same matrix patterns as their nodal counterparts, suggesting that (malignant) lymphoid cells generate (at least partly) their own specific microenvironment. In reactive lymphoid tissue β1 integrins were mainly found on resident cells and except for α4, α5 (and β1) the lymphoid cells expressed very little, if any, β1 integrins. In comparison, expression of these integrins on lymphoma cells was reduced (follicular lymphomas) or could not be detected at all (diffusely growing lymphomas); this might contribute to the growth pattern and metastatic properties of the tumours.  相似文献   
26.
本文报告了1990年5月以来脑干区大型、复杂占位病变15例.其中,位于脑干内3例,脚间窝2例,岩尖部4例,全岩骨区1例,全斜坡区2例,第四脑室内3例.本组采用以扩大了的岩骨入路为主的联合入路,行肿瘤全切除8例,次全切除5例.2例仅作了活检加减压术.除1例死亡外,均恢复良好.本文结合文献,对脑干区手术入路进行了讨论.  相似文献   
27.
一种便携式野战多功能骨科手术器械。重量仅1.1kg,体积为215mm×105mm×15mm,如铅笔盒,而功能多达33种,具有结构紧凑、操作简便、一械多用、轻巧便携。价廉实用、效价比高的特点。是基层巡诊、抢险救灾救治中适用的骨科器械。  相似文献   
28.
From September 1984 to December 1989, 38 patients of pediatric age with localized bone sarcomas received intraoperative radiotherapy (IORT) as part of a multidisci plinary treatment program. The age ranged from 6 to 21 years. The tumor histologies were 22 osteosarcomas and 16 Ewing's sarcomas. Thirty-four had initial primary disease (90%) and 4 were treated for local recurrence (10%). IORT was used on 32 untreated patients and in 6 previously treated with external beam radiotherapy (EBR). The IORT field included the surgically exposed tumor bed area. Single radiation doses ranging from 10 to 20 Gy were delivered, using 6–20 MeV electron beams. The median follow-up time for the entire group is 25 months (2–65+ months). The projected 5-year disease-free and overall survival rates are 65% and 69%, respectively. One patient developed a local recurrence in each histological group: one chondroblastic osteosarcoma and one cervical Ewing's sarcoma. Six patients died from metastatic progression: 3 initially recurrent tumors and three primary disease cases. Severe neuropathy and soft tissue necrosis were seen in some patients as IORT related complications. IORT is a feasible technique to be integrated in multidisciplinary programs that may promote local control in pediatric and adolescent patients with bone sarcomas. Peripheral nerves are dose-limiting tissue structures for IORT.  相似文献   
29.
We describe a patient with severe combined immunodeficiency and transplacental transfer of maternal T cells who received an unfractionated HLA-identical sibling bone marrow transplant without prior conditioning. He presented prior to transplantation with a dermatitis later diagnosed as mild graft versus host disease. He had a normal absolute lymphocyte count, but proliferative responses to mitogens were very low. Antigens of the noninherited maternal HLA haplotype were detected on his blood lymphocytes. After transplantation, he developed a severe reaction including fever, cutaneous erythema and hepatosplenomegaly. Lymphocytes carrying the noninherited maternal HLA haplotype disappeared from his circulation, and his unprimed mononuclear cells became spontaneously cytotoxic to maternal lymphoblasts. He subsequently developed a lymphocytosis of 69,000/mm3, diarrhea, elevated transaminases and a worsening rash, necessitating treatment with immunosuppressive agents. Full T-cell engraftment and evidence of B-cell function later ensued and spontaneously cytotoxic lymphocytes against maternal cells disappeared by 47 days post-transplantation. We postulate that the patient's constellation of signs and symptoms after transplantation represented a combination of severe graft versus graft and mild graft versus host reactions.  相似文献   
30.
6例肺癌患者接受了大剂量卡铂并自体骨髓移植治疗 ,卡铂剂量从 5 60~ 1375 mg/ m2 ,5例加用 VP~ 1630 0 mg,1例并用 MMC6mg和 VCR2 mg;主要毒性反应为白细胞、中性粒细胞、血小板减少和脱发 ( WHO毒性反应 ~ 级 )其次是贫血、皮肤粘膜出血、呕吐和可逆性肝功能损害 ,口腔粘膜溃疡及轻度发烧各 2例 ,一过性蛋白尿、室上性心动过速和便秘各 1例 ,尿素氮和肌酐未见升高 ;全部患者骨髓均获解救 ,从自体骨髓回输到骨髓造血功能重建成功平均 2 6.67( 17~ 32 )天  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