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   11352篇
  免费   1216篇
  国内免费   827篇
耳鼻咽喉   80篇
儿科学   110篇
妇产科学   149篇
基础医学   1383篇
口腔科学   226篇
临床医学   1615篇
内科学   1678篇
皮肤病学   84篇
神经病学   660篇
特种医学   523篇
外国民族医学   7篇
外科学   1070篇
综合类   1999篇
现状与发展   3篇
一般理论   1篇
预防医学   749篇
眼科学   295篇
药学   1247篇
  22篇
中国医学   706篇
肿瘤学   788篇
  2024年   39篇
  2023年   189篇
  2022年   533篇
  2021年   629篇
  2020年   515篇
  2019年   421篇
  2018年   459篇
  2017年   436篇
  2016年   353篇
  2015年   562篇
  2014年   640篇
  2013年   514篇
  2012年   823篇
  2011年   897篇
  2010年   554篇
  2009年   447篇
  2008年   545篇
  2007年   596篇
  2006年   555篇
  2005年   590篇
  2004年   388篇
  2003年   317篇
  2002年   306篇
  2001年   252篇
  2000年   259篇
  1999年   312篇
  1998年   178篇
  1997年   177篇
  1996年   142篇
  1995年   106篇
  1994年   117篇
  1993年   58篇
  1992年   75篇
  1991年   73篇
  1990年   80篇
  1989年   59篇
  1988年   42篇
  1987年   30篇
  1986年   33篇
  1985年   31篇
  1984年   14篇
  1983年   7篇
  1982年   13篇
  1981年   11篇
  1980年   2篇
  1979年   4篇
  1978年   2篇
  1977年   4篇
  1976年   3篇
  1942年   1篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
21.
周涛  王端顺 《解剖学报》2002,33(1):54-58
目的 探讨双丁酰 环核苷酸 (db cAMP)对转化细胞增殖及细胞表型作用的机理。 方法 以流式细胞光度术 (flowcytometry ,FCM)、软琼脂集落形成、放射免疫、Northern印迹和激酶活性分析等方法观察db cAMP对转化的C3H1 0 T1 2 小鼠成纤维细胞增殖、细胞表型、钙调素 (calmodulin ,CaM)表达及蛋白激酶Ⅱ (proteinkinaseⅡ ,PKⅡ )活性的影响。 结果 db cAMP(1mmol L)使C3H1 0 T1 2 转化细胞增殖及软琼脂集落形成能力受到显著抑制 ,转化细胞中CaM的表达及PKⅡ活性明显高于正常细胞 ,经db cAMP处理后也受到明显抑制。 结论 细胞转化及cAMP的诱导分化作用与PKⅡ活性的改变有密切相关性  相似文献   
22.
Rao ZR  Ge X  Qiou JY  Yang T  Duan L  Ju G 《Neuroscience research》2000,38(2):139-146
Forebrain heat shock protein 70 (HSP70) immunohistochemical reactivity was investigated in rats subjected to gamma knife irradiation focusing on the right caudate putamen nucleus. The forebrain sections of all experimental animals were processed with anti-HSP70 antiserum and then by avidin-biotin peroxidase complex immunohistochemistry after gamma ray irradiation with a dose of 100Gy and they each survived for different times (from 30 min to 30 days). Some neurons, glial cells, and endothelial cells were HSP70-like immunoreactivity (HSP70-LI) positive. HSP70-LI was mainly distributed in the target area of irradiation, as well as in non-target regions, e.g. the cortex, hippocampus, and hypothalamus, etc. The expression and change of HSP70-LI from 3 h to 30 days after irradiation followed the following rules: (1) Within 3 to 24 h, the dilated vessels with HSP70-LI endothelial cells were found at first, and a few lightly stained HSP70-LI neurons and glias were observed in the target and non-target regions; (2) In 3-7 days, darkly stained HSP70-LI neurons and glias were apparently increased and formed an expression peak. From 14 to 30 days, HSP70-LI cells were distinctly decreased and became weakly stained or negative. These results suggested that although the irradiation target of the gamma knife was localized, the response to irradiation occurred extensively.  相似文献   
23.
目的:评价^32P灌注球囊预防再狭窄的有效性、可行性和安全性。方法:对猪冠状动脉左前降支行过度球囊扩张术后,治疗组以^32P作血管内照射,对照组作假照射。术后35d收获目标血管、检测血管形态、细胞增殖百分比等。结果:治疗组血管腔面积较对照组明显增大(P<0.01),新生内膜面积、血管狭窄程度和各层PCNA阳性细胞明显减小(P均<0.01)。结论:^31P灌注球囊照射预防冠状动脉再狭窄有效、安全而且可行。  相似文献   
24.
25.
胆汁泡蛋白ELISA检测法的建立与初步临床应用   总被引:1,自引:0,他引:1  
目的 建立胆汁泡蛋白快速检测法,筛选有效的胆石症防治手段。方法 获取33.5kd胆汁泡蛋白,通过微量抗原免疫法获得高效价抗体,建立ELISA标准曲线;并应用ELISA法测定正常人、胆石症患者胆汁和血清中泡蛋白含量,同时观察不同溶石防药和利胆冲剂、胆酸钠等对泡蛋白的影响。结果 建立了ELISA标准曲线,其曲线方程为Y=0.035X(r=0.99);正常人胆汁和血清中33.5kd泡蛋白含量都明显较胆固  相似文献   
26.
Humaninsulin likegrowthfactor Ⅱ (IGF Ⅱ )isa 6 7aminoacidsingle chainpeptide ,whichisinvolvedinfetalgrowthanddevelop ment[1] .Thegrowth promotingpropertiesofIGF Ⅱ ,aswellastheirstructuralhomologytoproinsulinandIGF Ⅰarereflectedinthenameofthepeptides .Itisalsohelpf…  相似文献   
27.
1993年7月~1998年1月为103例(106只眼)难治性青光眼患者施行国产房水引流物(HAD)置入术。术后平均随访328月。术后1年时平均眼压22±1.4kPa。术后1~5年的手术成功率分别为838%,804%,771%,710%及643%。术中联合应用丝裂霉素C的病例,其术后1年时的成功率为895%。术后常见的并发症有持续性浅前房,局限性脉络膜脱离及眼压升高等。认为HAD可用于治疗难治性青光眼。  相似文献   
28.
Interventions are needed to improve the quality of care for schizophrenia. However, in designing these interventions it would be helpful to understand better which patients are at highest risk for poor-quality care and why care for this disorder is often of poor quality. We study the extent to which patient and treatment factors are associated with poor-quality care in 224 patients randomly sampled from two mental health clinics. Quality of medication management is evaluated using an established method based on national treatment recommendations. Multivariate regression is used to study the effect of patient and treatment factors on treatment quality, controlling for provider. Risk for poor-quality care was greater for patients who were more severely ill, older, and less compliant with treatment recommendations. There were trends toward poor management of symptoms in men and substance abusers, and poor management of side effects in Black patients. Provision of poor-quality care was associated with failure to document symptoms and side effects in the medical record. Interventions to improve care for schizophrenia should attend to the need for accurate clinical assessment and strategies for managing challenging clinical situations.  相似文献   
29.
Cyclophosphamide (CY) and its derivative ifosfamide are alkylating agents used to treat osteosarcoma (OS). The purpose of these studies was to determine whether alkylating agents affect the expression of Fas ligand (FasL) and whether interleukin 12 enhances the sensitivity of human OS cells to alkylating agents. 4-Hydroperoxycyclophosphamide (4-HC), the preactivated CY compound, and 4-hydroperoxydidechlorocloclophosphamide (4-HDC), its nonalkylating analogue, human OS LM6 cells, and a clone of cells derived by transfection with the interleukin 12 gene (LM6-#6) were used for these studies. Incubation of LM6 and LM6-#6 with 10 micro M 4-HC increased the expression of FasL mRNA (2.5- and 3.0-fold, respectively). By contrast, 4-HDC, Adriamycin (ADR), cisplatin (CDP), and methotrexate (MTX) had no effect on FasL mRNA expression. Increased FasL expression after treatment with 4-HC was also demonstrated by immunohistochemistry and flow cytometry. Drug-induced FasL was functional and mediated cell death. We examined the effect of FasL up-regulation by 4-HC on LM6 and LM6-#6 cells. Flow cytometry showed that LM6-#6 cells expressed 2.2-fold more Fas than LM6 cells. Cytotoxicity of 4-HC, 4-HDC, ADR, CDP, and MTX on LM6, LM6-neo, and LM6-#6 were quantified. Colony-forming assay revealed an IC(50) of 2.10 micro M for 4-HC in LM6-neo cells compared with 0.41 micro M in LM6-#6 cells. The IC(50) for 4-HDC, ADR, CDP, and MTX were not significantly different between the two cell lines. We concluded that the increased expression of Fas enhanced LM6-#6 sensitivity to 4-HC. These data indicate that Fas/FasL may be involved in the cytotoxic pathway of CY. Combining biological agents with chemotherapeutic agents that have complementary Fas/FasL pathway actions may offer new therapeutic alternatives.  相似文献   
30.
PURPOSE: The process of metastasis requires the single tumor cell that seeds the metastatic clone to complete a complex series of steps. Identifying factors responsible for these steps is essential in developing and improving targeted therapy for metastasis. Resistance to receptor-mediated cell death, such as the Fas/Fas ligand pathway, is one mechanism commonly exploited by metastatic cell populations. EXPERIMENTAL DESIGN AND RESULTS: LM7, a subline of the SAOS human osteosarcoma cell line with low Fas expression, was selected for its high metastatic potential in an experimental nude mouse model. When transfected with the full-length Fas gene (LM7-Fas), these cells expressed higher levels of Fas than the parental LM7 cells or LM7-neo control-transfected cells. These cells were also more sensitive to Fas-induced cell death than controls. When injected intravenously into nude mice, the LM7-Fas cell line produced a significantly lower incidence of tumor nodules than control cell lines. Lung weight and tumor nodule size were also decreased in those mice injected with LM7-Fas. Levels of Fas were quantified in osteosarcoma lung nodules from 17 patients. Eight samples were Fas negative, whereas the remaining 9 were only weakly positive compared with normal human liver (positive control). CONCLUSIONS: Our results demonstrate that altering Fas expression can impact the metastatic potential of osteosarcoma cells. We conclude that the increase of Fas on the surface of the LM7 osteosarcoma cells increased their sensitivity to Fas-induced cell death in the microenvironment of the lung, where Fas ligand is constitutively expressed. Thus, loss of Fas expression is one mechanism by which osteosarcoma cells may evade host resistance mechanisms in the lung, increasing metastatic potential. Fas may therefore be a new therapeutic target for osteosarcoma.  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