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   416篇
  免费   7篇
  国内免费   2篇
耳鼻咽喉   1篇
儿科学   1篇
妇产科学   3篇
基础医学   53篇
口腔科学   6篇
临床医学   21篇
内科学   32篇
皮肤病学   29篇
神经病学   23篇
特种医学   13篇
外科学   9篇
综合类   19篇
预防医学   12篇
眼科学   2篇
药学   102篇
中国医学   30篇
肿瘤学   69篇
  2023年   1篇
  2020年   2篇
  2019年   11篇
  2018年   13篇
  2017年   6篇
  2016年   2篇
  2015年   5篇
  2014年   22篇
  2013年   15篇
  2012年   13篇
  2011年   16篇
  2010年   18篇
  2009年   22篇
  2008年   24篇
  2007年   21篇
  2006年   16篇
  2005年   17篇
  2004年   20篇
  2003年   13篇
  2002年   12篇
  2001年   4篇
  2000年   8篇
  1999年   11篇
  1998年   6篇
  1997年   4篇
  1996年   9篇
  1995年   6篇
  1994年   8篇
  1993年   10篇
  1992年   9篇
  1991年   8篇
  1990年   2篇
  1989年   10篇
  1988年   10篇
  1987年   7篇
  1986年   7篇
  1985年   11篇
  1984年   11篇
  1983年   2篇
  1982年   4篇
  1981年   1篇
  1980年   2篇
  1979年   3篇
  1978年   2篇
  1975年   1篇
排序方式: 共有425条查询结果,搜索用时 15 毫秒
11.
目的:本文探讨血清CA153、CEA和TPA联检在术前乳腺肿瘤鉴别诊断中价值,以期为乳腺癌患者即时手术提供帮助.方法:采用放射免疫分析,检测乳腺肿瘤患者和健康人群血清CA153、CEA和TPA含量.结果:在CA153、CEA和TPA血清学检测中,术前乳腺癌组与乳腺良性肿瘤和健康人群组表达水平存在明显差异.术前乳腺癌组阳性率:CA153为63.8%,CEA为22.4%,TPA为62.1%;术前乳腺癌组联检阳性率:CA153和CEA为69.8%,CA153和TPA为87.1%,三者联检为90.5%;术前乳腺癌组检测特异性:CA153为77.9%,CA153和CEA联检为77.9%,CA153和TPA联检为71.9%,三者联检为73.4%.结论:当CA153、CEA和TPA三者联检时,术前乳腺癌组诊断阳性率显著提高,阳性组特异性无明显下降,值得临床推广应用.  相似文献   
12.
13.
We characterized the cell growth and Epstein-Barr virus (EBV) reactivation for EBV infected epithelial cell lines, GT38, GT39, and GTC-4 using 12-O-tetradecanoylphorbol-13-acetate (TPA). These cell lines grew similarly in liquid medium, and formed colonies in soft agar. The cell growth was inhibited with TPA, dose-dependently in liquid medium. The colony formation was enhanced with low concentrations of TPA, but was inhibited with high concentrations. The latent EBV was reactivated with high concentrations of TPA as shown by the expression of EBV BZLF1 gene product ZEBRA. The effects of TPA on GTC-4 were compared with a Burkitt's lymphoma cell line Raji. The mode of actions of TPA in GTC-4 was different from Raji in terms of cell growth and EBV reactivation. The effective concentrations of TPA for cell growth inhibition and EBV reactivation were higher in Raji than GTC-4. Cell cycle analysis showed that TPA (20 ng/ml) induced cell cycle arrest to Raji but not to GTC-4; however, the rate of trypan blue stained cells increased in the TPA treated GTC-4 but not Raji. These results demonstrated that TPA affects differentially for the stimulation and inhibition of cell growth, and also EBV reactivation depends on TPA concentrations and cell types.  相似文献   
14.
H. Nolte    M. Poulsen    P. O. Schiøstz  P. Stahl  Skov 《Allergy》1990,45(6):427-435
This study had two purposes. First, to examine a possible functional heterogeneity of IgE regulating basophil histamine release and the effect of using two different donor cells for passive sensitization experiments. Second, to investigate basophils not releasing histamine to anti-IgE by stimulating protein kinase C with the addition of the phorbol-ester, TPA. In consecutive experiments responding donor basophils were passively sensitized with plasma from non-responding subjects. Thus, the first set of experiments included passive sensitization of acid treated donor basophils from one atopic and one non-atopic patient with plasma from 29 children with exogenous asthma to grass pollen, cat dander, or dust mites. Different secretagogues (anti-IgE, Concanavalin A, and N-formyl-methionyl-leucyl-phenylalanine) induced different histamine release responses due to a cellular property of the basophils not related to the type of IgE bound to the cell membrane. It was demonstrated that the allergen-induced histamine release did not depend on the extract or type of IgE when the biological activity of each extract and serum-specific IgE levels were similar. However, the atopic donor cells released significantly (P less than 0.05) more histamine than non-atopic donor cells. Thus, histamine release depends on the type of secretagogues and a cellular property which is maybe influenced by the presence of serum factors and a certain type of IgE in the serum of atopics. The second set of experiments included 10 patients (6 atopics and 4 non-atopics) with non-histamine releasing basophils. In the presence of 10 ng/ml TPA, however, seven of 10 patients released histamine at anti-IgE challenge. Three months later two additional patients became responsive in the presence of TPA. By passive sensitization of responding donor basophils the non-responding patients were shown to possess functionally intact IgE. Thus, the discrepancies sometimes observed between clinical symptoms, serological IgE-antibody measurements and histamine release testing in allergic patients may be related to a cellular property of basophils.  相似文献   
15.
用原位杂交荧光显示法观察了人淋巴细胞在促癌变剂黄芫花提取物(WCE)和12-0-十四烷巳豆醇-13乙酸酯(TPA)处理后,间期核仁rDNA的定位与数量改变,并与丝裂原植物血细胞凝集素(PHA)的效应作了比较,同时用银染色法观察了核仁。对照组淋巴细胞核仁小,原位杂交的rDNA为少数明亮荧光斑和分散的荧光点。经促癌变剂WCE和TPA处理后,银染色的核仁增大,银染颗粒增多,表明rDNA转录活化。原位杂交证明rDNA信号数目明显扩增,许多荧光小点断续相连形成网织状结构,与PHA刺激核仁转录活化的表现一致。对核仁内所含银染颗粒和rDNA荧光斑点数均值的统计学分析表明,WCE、TPA和PHA各加药组均明显多于对照组。3个加药组之间无明显差别。提示两种促癌变剂皆具有刺激核仁rDNA扩增和转录活化的效应。  相似文献   
16.
17.

Purpose

To compare the technical and clinical effectiveness of ultrasound-accelerated endovascular thrombolysis (USAT) versus pigtail catheter–directed thrombolysis (PCDT) for the treatment of acute pulmonary embolism (PE).

Materials and Methods

A single-center retrospective study of patients treated with USAT or PCDT for acute massive or submassive PE between January 2010 and December 2016 was performed by reviewing electronic medical records. Sixty treatments were reviewed (mean patient age, 56.7 y ± 14.6), including 52 cases of submassive PE (21 treated with USAT, 31 with PCDT) and 8 cases of massive PE (3 treated with USAT, 5 with PCDT). Endpoints included pulmonary artery pressure (PAP), Miller PE severity index, tissue plasminogen activator (TPA) dose, infusion duration, procedural variables, and complications.

Results

Demographics, PE severity, and right:left ventricular diameter ratios were similar between groups. USAT and PCDT significantly reduced mean PAP (reductions of 7.4 mm Hg [P = .002] and 8.2 mm Hg [P < .001], respectively) and Miller index scores (reductions of 45.8% [P < .001] and 53% [P < .001], respectively) with similar effectiveness (P = .47 and P = .15, respectively). Procedure (P < .001) and fluoroscopy (P = .001) times were significantly longer in the USAT group. The USAT group underwent fewer sessions (2.2 ± 0.6 vs 2.4 ± 0.6; P = .17) with shorter infusion times (23.9 h ± 8.8 vs 30.4 h ± 12.6; P = .065) and a lower total dose of TPA (27.1 mg ± 11.3 vs 30.4 mg ± 12.6; P = .075) compared with the PCDT group, but the differences were not significant. Complications (P = .07) and 30-day mortality rates (P = .56) were not significantly different between groups.

Conclusions

USAT and PCDT demonstrated comparable effectiveness and safety in the treatment of patients with acute PE.  相似文献   
18.
Purpose: Although radiofrequency (RF) radiation is not considered mutagenic, it has been suggested as a promoter of tumorigenesis. To study if RF radiation has a tumor promoting effect, we exposed mice with skin tumorigenesis initiated by 7,12-dimethybenz[α]anthracene (DMBA) to RF radiation.

Materials and methods: Eighty male ICR mice were subjected to a single DMBA application (100 μg/100 μl acetone/mouse) on shaved dorsal skin at the age of 7 weeks. After one week, the mice were randomized into four equal groups of 20 mice each: i.e., sham-, 849 MHz-, 1,763 MHz-exposed, and 12-O-tetradecanoylphorbol-13-acetate (TPA)-treated groups. The RF exposure was conducted at a whole body average specific absorption rate (SAR) of 0.4 W/Kg, for 2 cycles of 45 min exposure with a 15 min interval each day, 5 days a week for 19 weeks. The TPA-treated group served as a positive control for skin tumorigenesis and were administered TPA (4 μg/100 μl acetone/mouse) twice weekly without RF exposure.

Results: All mice were examined weekly at a macroscopic level. No skin tumors were observed in any groups except in the TPA-treated positive control group. TPA is known tumor promoter in DMBA-induced skin carcinogenesis and tumor incidence in the TPA treated group was 95%. At week 20 after DMBA initiation, skin tissues were analyzed immunohistochemically using anti-proliferating cell nuclear antigen (PCNA) antibody. No differences were observed by pathological examination or by PCNA staining between the sham- and the RF-exposed groups. The expression of cyclin D1 and c-fos were detected only in the tumorous skin tissues of the TPA-treated group.

Conclusion: No evidence was found that RF radiation serves as a tumor promoter for skin tumors. Our data suggests that 849 MHz and 1,763 MHz RF radiations, similar to those emitted from mobile phones, do not have any promoting effect on skin tumor development in DMBA-initiated mice.  相似文献   
19.

Background

Orthopedic hip and knee surgeries are followed by a hypercoagulable state. Heparanase is implicated in inflammation, coagulation activation and angiogenesis. Recently, heparanase was shown to directly interact with tissue factor (TF) and to enhance the generation of factor Xa (Nadir et al., Haematologica, 2010). In addition, an assay assessing heparanase procoagulant activity has been lately developed (Nadir et al., Thromb Res, 2011). In the present study heparanase level and procoagulant activity in patients undergoing orthopedic surgery were assessed.

Methods

The study group included 50 orthopedic patients. 31 patients underwent hip surgery and 19 had knee operation. 15 individuals suffered from traumatic hip fractures and 35 had osteoarthrosis of hip or knee joints. All patients received prophylactic dose of enoxaparin starting 6-8 hours post operation and lasting for 5 weeks. Plasma samples were drawn preoperatively and at 1 hour, 1 week and 1 month post operation. Samples were tested for heparanase levels by ELISA and TF/heparanase complex activity, TF activity, heparanase procoagulant activity, factor Xa and thrombin levels using chromogenic substrates.

Results

Heparanase levels were significantly higher 1 hour and 1 week post operatively compared to preoperative levels (p < 0.05, p < 0.005, respectively). The most dramatic changes were observed in heparanase procoagulant activity reaching a 2 fold increase 1 week postoperatively and 1.7 fold increase 1 month after surgery (p < 0.0001, p < 0.0001, respectively). Levels of factor Xa and thrombin did not significantly change.

Conclusions

Heparanase is involved in coagulation activation of orthopedic surgery patients. Heparanase procoagulant activity is highest 1 week postoperatively and remains high 1 month after operation. Considering extending prophylactic anticoagulant therapy or evaluating heparanase procoagulant activity may potentially prevent late thrombotic events.  相似文献   
20.
Marine fishery products may contain high levels of arsenic, mainly in the form of organic arsenic compounds. Arsenobetaine has been identified as the predominant form occurring in marine fishery products. The potential initiating and promoting capacities of this compound were therefore investigated in vitro. In the Salmonella typhimurium assay, no mutagenicity was observed in strains TA97, TA98 and TA100 without activation or after addition of a liver-enzyme fraction or gut-flora extract. The compound was also negative in the forward mutation assay of the HGPRT gene and in the test for sister chromatid exchanges in V79 Chinese hamster cells. No inhibition of metabolic co-operation between V79 Chinese hamster cells was observed at arsenobetaine concentrations up to 10 mg/ml. In addition, arsenobetaine had no synergistic or antagonistic effects on the action of the positive controls benzo[a]pyrene and tetradecanoylphorbol-13-acetate.  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