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   9173篇
  免费   917篇
  国内免费   460篇
耳鼻咽喉   85篇
儿科学   105篇
妇产科学   119篇
基础医学   1058篇
口腔科学   216篇
临床医学   1103篇
内科学   1537篇
皮肤病学   300篇
神经病学   581篇
特种医学   273篇
外国民族医学   4篇
外科学   1037篇
综合类   1242篇
现状与发展   1篇
一般理论   1篇
预防医学   589篇
眼科学   175篇
药学   933篇
  7篇
中国医学   454篇
肿瘤学   730篇
  2024年   23篇
  2023年   134篇
  2022年   292篇
  2021年   453篇
  2020年   303篇
  2019年   323篇
  2018年   356篇
  2017年   300篇
  2016年   309篇
  2015年   420篇
  2014年   456篇
  2013年   502篇
  2012年   611篇
  2011年   699篇
  2010年   425篇
  2009年   335篇
  2008年   488篇
  2007年   509篇
  2006年   525篇
  2005年   474篇
  2004年   299篇
  2003年   315篇
  2002年   226篇
  2001年   190篇
  2000年   190篇
  1999年   206篇
  1998年   144篇
  1997年   122篇
  1996年   93篇
  1995年   82篇
  1994年   70篇
  1993年   42篇
  1992年   100篇
  1991年   58篇
  1990年   71篇
  1989年   36篇
  1988年   53篇
  1987年   47篇
  1986年   39篇
  1985年   35篇
  1984年   20篇
  1983年   17篇
  1982年   13篇
  1981年   20篇
  1980年   11篇
  1979年   21篇
  1976年   15篇
  1973年   9篇
  1969年   7篇
  1965年   6篇
排序方式: 共有10000条查询结果,搜索用时 453 毫秒
21.
Oral cancer progression and c-erbB-2/neu proto-oncogene expression.   总被引:2,自引:0,他引:2  
L Hou  D Shi  S M Tu  H Z Zhang  M C Hung  D Ling 《Cancer letters》1992,65(3):215-220
Monoclonal antibody PAb3 to c-erbB-2/neu protein was utilized in the immunoperoxidase staining of 86 human specimens from oral mucosa. These tissue specimens represented a spectrum from 7 normal to 9 simple hyperplasia, 15 mild dysplasia, 14 moderate dysplasia, 20 severe dysplasia and 21 squamous cell carcinoma. Our study indicated that as the cells acquire a more malignant phenotype, there was a progressive increase in neu expression. It also suggested that neu may be involved in the development of oral cancers and that its evaluation in the early stages may assist in the diagnosis and management of oral cancers.  相似文献   
22.
本文采用Iodogen法将鼠抗人胃癌单克隆抗体RSF9(IgM)予以131I标记,研究RSF9在荷人胃癌裸鼠中的定位和显像能力。结果表明,RSF9在体内能特异性地与肿瘤组织结合,T/NT比值随时间延长逐渐升高,96hT/NT比值均大于2.5,瘤/血比值为2.69,肿瘤定位指数达5.18,SPECT得到清晰的肿瘤图像。RSF9具有良好的体内导向定位能力。IgM型单抗也可用于肿瘤显像。  相似文献   
23.
Increased expression of certain glutathione S-transferase (GST) isoenzymes has frequently been associated with the development of resistance to alkylating agents and other classes of antineoplastic drugs in drug-selected cell lines. The question arises whether this phenomenon is causal or is a stress-induced response associated with drug resistance in these cell lines. We have constructed mammalian expression vectors containing the human GST mu and GST alpha 2 (Ha2) cDNAs and stably transfected them into the human breast cancer cell line MCF-7. Whereas the parental and pSV2neo-transfected cell lines display low GST activity, three individual transfected clones were identified in each group that expressed either GST mu or GST alpha 2. The range of GST activities was similar to those observed in cells selected for anticancer drug resistance. The GST mu specific activities were 56, 150, and 340 mlU/mg, compared with 10 mlU/mg of endogenous GST mu in control lines. Specific activities in GST alpha 2-transfected clones were 17, 28, and 52 mlU/mg, compared with no detectable alpha class GST in control lines. These clonal lines and the parental and pSV2neo-transfected control lines were tested for sensitivity to antineoplastic agents and other cytotoxic compounds. The clones with the highest activity in each group were 1.7-fold (GST alpha 2) to 2.1-fold (GST mu) resistant to the toxic effects of ethacrynic acid, a known substrate for GSTs. However, the GST-transfected cell lines were not resistant to doxorubicin, L-phenylalanine mustard, bis(2-chloroethyl)-1-nitrosourea, cisplatin, chlorambucil, or the GST substrates 1-chloro-2,4-dinitrobenzene or tert-butyl hydroperoxide. Thus, although L-phenylalanine mustard, bis(2-chloroethyl)-1-nitrosourea, chlorambucil, tert-butyl hydroperoxide, and 1-chloro-2,4-dinitrobenzene are known to be metabolized by glutathione-dependent GST-catalyzed reactions, there was no protection against any of these agents in MCF-7 cell lines overexpressing GST mu or GST alpha 2. We conclude that, at the levels of GST obtained in this transfection model system, overexpression of GST mu or GST alpha 2 is not by itself sufficient to confer resistance to these anticancer agents. These studies do not exclude the possibility that GST may be a marker of drug resistance or that other gene products not expressed in MCF-7 cells might cooperate with GST to confer drug resistance.  相似文献   
24.
1. Pharmacokinetics and pharmacodynamics of R- and S-verapamil and R- and S-norverapamil were studied at steady state following administration of 180 mg verapamil delivered by a controlled-release gastrointestinal therapeutic system (COER-verapamil). 2. Of the 30 young (19 to 43 years) and 30 elderly subjects (65 to 80 years) enrolled, approximately half of each age group were women; all subjects were healthy and none were smokers. 3. Mean R- and S-verapamil and R- and S-norverapamil Cmax, Cmin, and AUC values for elderly subjects were 1.2 to 2.2 times greater than those for young subjects; these differences were statistically significant at P < 0.05. Median tmax values for young and elderly subjects were not significantly different for any enantiomer. The mean half-life values of R- and S-verapamil for elderly subjects were approximately 20 h compared with approximately 13 h for young subjects, respectively. The mean half-life values of R- and S-norverapamil for elderly subjects were approximately 31 h and 20 h, respectively, compared with approximately 19 h and 21 h for young subjects, respectively. 4. In both age groups, the mean plasma verapamil concentrations of each enantiomer were higher for women than for men at all time points. 5. Mean arterial pressure (MAP) had a significant correlation to R- (r2 = 0.86) and S-verapamil (r2 = 0.87) concentration values that was not influenced by either gender or age of the patient. Change in PR-interval also had a significant correlation to R- and S-verapamil concentration values. However, the sensitivity of the response to changes in R- and S-verapamil concentration values in elderly subjects was about 1/5 of that in younger subjects.  相似文献   
25.
反相高效液相色谱法测定牛黄类中成药中胆汁酸的含量   总被引:7,自引:0,他引:7  
倪坤仪  王建  陈健  郁建  屠树滋 《药学学报》1994,29(8):624-633
反相高效液相色谱法测定牛黄类中成药中胆汁酸的含量倪坤仪,王建,陈健,郁建,屠树滋(中国药科大学210009)含牛黄的中成药种类很多,在医疗中具有广泛的用途。中药牛黄中主要成分为胆汁酸和胆红素。本文主要研究用HPLC法测定牛黄以及含牛黄中成药中胆汁酸的...  相似文献   
26.
27.
PURPOSE: Tumor responses in early-phase trials are used to determine whether new agents warrant further study. Given that spontaneous regressions are observed in melanoma and renal cell carcinoma, this study assessed whether tumor responses, particularly in these two tumor types, predict for future regulatory drug approval. EXPERIMENTAL DESIGN: The literature was reviewed to assess tumor response rates to cytotoxic agents in phase I and II trials in the following solid tumors: melanoma, renal cell carcinoma, non-small-cell lung cancer, breast cancer, ovarian cancer, colorectal cancer, and other solid tumors. Response rates were categorized and the relationship of these categories to the end point of regulatory drug approval was determined. RESULTS: Fifty-eight drugs were assessed in 100 phase I trials, and 46 of these drugs were also studied in 499 phase II trials. Higher overall response rates in both phase I trials (P = 0.03) and phase II trials (P < 0.0001) were predictive of regulatory approval. However, response in melanoma or renal cell carcinoma was not predictive for either phase I or phase II studies. CONCLUSIONS: For cytotoxic agents, although overall objective response rates reliably predict subsequent marketing approval, isolated responses in melanoma and renal cell carcinoma are not predictive.  相似文献   
28.
珊瑚型人工髋关节置换术的临床随访及松动原因的分析   总被引:5,自引:0,他引:5  
自1983年至今应用珊瑚型人工髋关节置换术共54例60髋。其中人工全髋关节置换术34例40髋,人工股骨头置换术20例20髋。在54例60髋珊瑚型人工髋关节置换术中,有37髋随访6个月~13年,平均随访时间约7年,疗效满意率为85.1%,其中假体松动4例占14.8%,髋臼松动2例7.4%。假体松动原因是假体与股骨负重界面之间没有达到稳定接触,假体与髓腔形状不相匹配,修整髓腔松质骨时,髓腔扩大器应比假体小一号,避免假体与界面存留缝隙。对于髋臼发育不良的患者应避免髋关节旋转中心向外侧移位,应向内上方加深髋臼以减少水平移位距离,其次髋臼植骨加盖勿在负重区。  相似文献   
29.
30.
本文研究了26株P_c~r或O_x~r金黄色葡萄球菌的细胞结合青霉素酶。证实它们除有细胞外青霉素酶还具有细胞结合青霉素酶。金黄色葡萄球菌的总青霉素酶活力为22947~387743u/ml。细胞外青霉素酶活力为140~2130u/ml,占总酶含量的1%以下(菌株85051例外);大量青霉素酶是细胞结合的青霉素酶,活力为19937~382033u/ml。  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