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   499篇
  免费   23篇
  国内免费   1篇
耳鼻咽喉   6篇
儿科学   8篇
妇产科学   7篇
基础医学   89篇
口腔科学   11篇
临床医学   35篇
内科学   65篇
皮肤病学   5篇
神经病学   76篇
特种医学   9篇
外科学   34篇
综合类   9篇
预防医学   21篇
眼科学   1篇
药学   53篇
中国医学   1篇
肿瘤学   93篇
  2022年   4篇
  2021年   4篇
  2020年   7篇
  2019年   10篇
  2018年   13篇
  2016年   4篇
  2015年   8篇
  2014年   12篇
  2013年   15篇
  2012年   12篇
  2011年   23篇
  2010年   12篇
  2009年   16篇
  2008年   14篇
  2007年   16篇
  2006年   11篇
  2005年   12篇
  2004年   4篇
  2003年   8篇
  2002年   16篇
  2001年   16篇
  2000年   19篇
  1999年   24篇
  1998年   19篇
  1997年   13篇
  1996年   8篇
  1995年   10篇
  1994年   13篇
  1993年   16篇
  1992年   17篇
  1991年   11篇
  1990年   8篇
  1989年   9篇
  1988年   10篇
  1987年   10篇
  1986年   8篇
  1985年   11篇
  1984年   7篇
  1982年   4篇
  1977年   6篇
  1976年   3篇
  1975年   3篇
  1974年   5篇
  1972年   5篇
  1971年   5篇
  1970年   5篇
  1969年   3篇
  1968年   6篇
  1967年   4篇
  1966年   4篇
排序方式: 共有523条查询结果,搜索用时 15 毫秒
1.
2.
3.
An in vitro assay, which evaluates drug effect on 3H-thymidine incorporation, was used to investigate the absolute and relative activities of cisplatin (DDP), carboplatin (CBDCA) and iproplatin (CHIP) on 317 specimens from untreated tumors, including breast and ovarian cancers and malignant melanomas. Similar activities were generally observed for DDP and CHIP, whereas CBDCA exhibited a lower, although not significantly different cytotoxicity on breast and ovarian cancers. The relative activities of Platinum analogues were analyzed on 239 two-way drug sensitivity comparisons. The overall agreement rates ranged from 80.2 to 83.9% for the different comparisons. High coresistance, from 61.1 to 93.8%, was observed for all the comparisons, regardless of the tumor type. Cosensitivity rates were poor for breast and ovarian cancers, from 0 to 37.5%, whereas for melanomas an association in sensitivity was observed in 80% of the cases.  相似文献   
4.
The effect of oral administration of AF 1312TS upon the testicular germinal epithelium was studied in the rat and monkey. A single oral dose of 100 or 200 mgm/kgm given to mature male rats was not effective, but five consecutive doses of 200 mgm/kgm produced marked decrease in testicular weight and complete inhibition of spermatogenesis, while the weight and histology of the prostate and seminal vesicles were not affected. Daily doses of 10 mgm/kgm for 37 weeks or five consecutive doses of 50 mgm/kgm for 1 week were ineffective in the monkey. However, when the five dose regimen was followed by single weekly doses of 50 mgm/kgm for 6 months, complete inhibition was achieved and maintained in the monkey after 8 weeks. Daily doses of 100 mgm/kgm for 6 months resulted in inhibition of spermatogenesis.Preliminary studies with AF 1890 (an analog of AF 1312TS) given at levels of 50 mgm/kgm for 5 days to rats resulted in complete inhibition of spermatogenesis. The activity of this analog was four times greater than AF 1312TS. In monkeys, a daily dose of 200 mgm/kgm for 2 weeks also resulted in suppression of spermatogenesis.  相似文献   
5.
目的 真核表达人呼吸道合胞病毒(human respiratory syncytial virus,SV)融合蛋白(fusion protein,),并完成蛋白纯化及纯度测定.方法 根据编码F蛋白的基因序列设计引物,CR方法扩增出3'端带His标签的F基因序列,克隆入pGEM-T-easy载体,经核酸序列分析后,进一步克隆到pcDNA3.1( )真核表达载体,限制性内切酶鉴定,用脂质体Lipofectamine2000转染COS-7细胞,2 h后再用Westem blot检测目的蛋白的表达.Ni柱亲和层析纯化COS-7细胞表达的F蛋白,高效毛细管电泳分析纯化后蛋白纯度.结果 核酸序列分析证实获得带His标签的RSV F基因序列,没有发生无义突变.转染COS-7细胞后,利用Western blot方法检测到F蛋白的特异性条带,纯度达99%以上.结论 初步建立了真核表达RSV F蛋白的纯化方法,为进一步优化RSV F蛋白制备条件及单克隆抗体及诊断试剂等研究奠定了基础.  相似文献   
6.
The ability of lonidamine (LND), an energolytic derivativeof indazole-carboxylic acid, to modulate the cytotoxic activityof cisplatin (CDDP) and epidoxorubicin (EPI), singly orin combination, was investigated in two human breastcancer cell lines (MCF7 and T47D). A 72-hrpost-incubation with a non-cytotoxic concentration of LND (75M) increased the activity of a 1-hr CDDPtreatment as well as that of a 1to 16-hr EPI treatment. A different pattern ofinteraction among the drugs and modulator was observedas a function of the sequence of drugtreatment. Specifically, supra-additive or additive effects of thecombination were obtained in the two cell linesaccording to the different treatment schemes. In particular,the maximum potentiation was observed in MCF7 cellssimultaneously exposed to CDDP, EPI and LND for1 hr and then post-incubated with LND for72 hr, and in T47 first exposed toEPI and LND, then to CDDP and LND,and finally post-incubated with LND. Flow cytometric analysisof MCF7 cell distribution in the different cyclephases showed that combined treatment with EPI/CDDP/LND wasable to stabilize cell cycle perturbations (mainly G2Maccumulation) induced by individual agents. The ability ofLND to potentiate CDDP and EPI cytotoxicity, andthe consideration that LND causes side effects differentfrom those caused by alkylating agents and anthracyclines,make this compound an attractive candidate for multidrugcombination therapy in breast cancer.  相似文献   
7.
The ability of lonidamine (LND), an energolytic derivative of indazol-carboxylic acid, to modulate the cytotoxic activity of idarubicin (IDA) and doxorubicin (DX) was investigated in two human lymphoma cell lines (H9 and U937). A different pattern of interaction between the drugs was observed as a function of treatment sequence. Specifically, a 24-h postincubation with a non-cytotoxic concentration of LND (75 mu M) increased the activity of a 1-h anthracycline treatment in both cell lines. However, the extent of potentiation for IDA was more than twofold that of DX. No enhancement of anthracycline activity was observed when LND preceded IDA. For comparative purposes, the modulating effect of all-trans-retinoic acid (ATRA) on the cytotoxicity of IDA was evaluated according to different treatment schemes in both lymphoma cell lines. In U937 cells, which undergo monocytic differentiation after exposure to retinoids, a marked increase in LDA activity was obtained following a 48-h postincubation with 1.5 mu M ATRA. No potentiation of anthracycline activity was obtained using the opposite drug sequence. In H9 cells, no significant interference between ATRA and IDA was observed independent of the modality of drug administration. The ability of LND to potentiate IDA activity, and the consideration that LND causes side effects different from those caused by anthracyclines, make this compound an attractive candidate for multidrug combination therapy in hematological neoplasms.  相似文献   
8.
This study assessed the use of transcranial Doppler ultrasound in detecting selective changes in cerebral blood flow velocity during emotional processes. The role of the respective hemispheres in emotional processing is controversial. Cerebral control of emotional processing has previously been investigated by analysis of patients with unilateral brain damage, experiments with selective stimulation of only one hemisphere, and more recently by imaging techniques measuring local cerebral blood flow. We investigated mean flow velocity continuously and simultaneously in both the right and left middle cerebral arteries (MCAs) in 16 healthy right-handed young subjects at rest and during the performance of three tasks: task 1: 15 slides with nonemotional content; task 2: 15 slides with negative emotional content; task 3: 15 slides with nonemotional content with different content from that in task 1. The three tasks produced significantly different effects on the right and left hemispheres. During the two nonemotional tasks the increase in mean flow velocity over basal values was similar in the two MCAs (task 1: left MCA = 3.27 ± 1.9%; right MCA = 3.63 ± 2.1%; task 3: left MCA = 2.42 ± 0.7%; right MCA = 2.56 ± 1.3%); the negative emotional task was accompanied by a significantly higher increase in the right (11.31 ± 1.6%) than in the left MCA (4.72 ± 3.7%; analysis of variance two-way interaction: side of recording x task, F = 43.6, P < 0.001). These results show the possibility of obtaining specific functional information from bilateral transcranial Doppler ultrasound and suggest the involvement of the right hemisphere in emotional processing. Received: 4 March 1999 Received in revised form: 29 June 1999 Accepted: 5 August 1999  相似文献   
9.
The mechanism of action of fish oil (FO), currently used in different chronic inflammatory conditions such as rheumatoid arthritis (RA), is not completely understood, although it is thought that it could alter the metabolism of endogenous autacoids. In addition, we hypothesized that the known capability of fatty acids (FA) of stabilizing serum albumin and perhaps other proteins, may be of pharmacological relevance considering that it is shared by other anti-rheumatic agents (e.g. nonsteroidal antiinflammatory drugs). Thus, we studied the effect of oral administration of FO and corn oil (CO), a vegetable oil with a different composition, on the stability of rat serum proteins, evaluated by a classical in vitro method based on heat-induced protein denaturation. FO, and, to a lower extent, CO inhibited heat-induced denaturation of rat serum (RS): based on the inhibitory activity (EC50) of the major fatty acids against heat-induced denaturation of RS in vitro, it was possible to speculate that in vivo effects of palmitic acid (C16:0) and eicosapentaenoic acid (EPA, C20:5, n-3) may be more relevant than that of linolenic acid (C18:2). To better investigate this phenomenon, we extracted albumin from the serum of animals treated or not with FO with a one-step affinity chromatography technique, obtaining high purity rat serum albumin preparations (RSA-CTRL and RSA-FO), as judged by SDS-PAGE with Coomassie blue staining. When these RSA preparations were heated at 70 degrees C for 30 min, it was noted that RSA-FO was much more stable than RSA-CTRL, presumably due to higher number of long chain fatty acids (FA) such as palmitic acid or EPA. In conclusion, we provided evidences that oral administration of FO in the rat stabilizes serum albumin, due to an increase in the number of protein bound long chain fatty acids (e.g. palmitic acid and EPA). We speculate that the stabilization of serum albumin and perhaps other proteins could prevent changes of antigenicity due to protein denaturation and glycosylation, which may trigger pathological autoimmune responses, suggesting that this action may be involved in the mode of action of FO in RA and other chronic inflammatory diseases.  相似文献   
10.
p53 and cathepsin D expression was investigated in 300 primary breast cancers by the avidin-biotin immunoperoxidase method using two murine monoclonal antibodies: PAb1801 and anti-procathepsin D, respectively. The frequency of p53- and cathepsin D-positive cells varied widely among different tumors and most tumors (82% and 86%) at least occasionally showed positive cells. The two biological markers were unrelated to one another, to cell proliferative rate and ploidy and were differently related to other biological and pathological features. In particular, p53 was directly related to tumor size and nodal involvement and inversely related to the presence of steroid receptors. Conversely, cathepsin D was directly related only to nodal involvement.  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