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   3609篇
  免费   361篇
  国内免费   200篇
耳鼻咽喉   18篇
儿科学   13篇
妇产科学   107篇
基础医学   134篇
口腔科学   15篇
临床医学   160篇
内科学   231篇
皮肤病学   38篇
神经病学   43篇
特种医学   51篇
外国民族医学   7篇
外科学   135篇
综合类   551篇
预防医学   51篇
眼科学   45篇
药学   1324篇
  3篇
中国医学   261篇
肿瘤学   983篇
  2024年   6篇
  2023年   43篇
  2022年   73篇
  2021年   96篇
  2020年   98篇
  2019年   87篇
  2018年   77篇
  2017年   134篇
  2016年   136篇
  2015年   136篇
  2014年   193篇
  2013年   403篇
  2012年   231篇
  2011年   236篇
  2010年   221篇
  2009年   178篇
  2008年   216篇
  2007年   216篇
  2006年   234篇
  2005年   197篇
  2004年   161篇
  2003年   120篇
  2002年   119篇
  2001年   98篇
  2000年   82篇
  1999年   75篇
  1998年   66篇
  1997年   59篇
  1996年   33篇
  1995年   25篇
  1994年   19篇
  1993年   20篇
  1992年   13篇
  1991年   15篇
  1990年   7篇
  1989年   10篇
  1988年   12篇
  1987年   7篇
  1986年   8篇
  1985年   4篇
  1984年   5篇
  1982年   1篇
排序方式: 共有4170条查询结果,搜索用时 15 毫秒
1.
目的探讨紫杉醇联合卡铂化疗治疗卵巢癌的效果分析。方法选自2018年5月-2019年5月132名符合入组以及排除标准的患者,随后研究人员将患者分为对照组以及研究组,分组应按照科学、合理、随机的标准,两组患者分别均有67例,对照组患者按照研究要求,接受卡铂化疗治疗,研究组患者按照研究要求,接受紫杉醇联合卡铂化疗治疗,两组患者分别接受不同的治疗,评估患者的临床效果,对比两组患者的观察指标,如:T细胞亚群、临床疗效。结果治疗后,CD8、CD4、CD3、CD4/CD8,研究组高于对照组;研究组中,CR+PR+SD人数多于对照组患者,且治疗总有效率高于对照组患者(P<0.05)。结论紫杉醇联合卡铂化疗治疗卵巢癌,能够提升患者自身的免疫功能,促进疾病的好转。  相似文献   
2.
3.
目的 观察脂质体Dotap包裹反义脱氧寡核苷酸对酪氨酸酶(TYR)的调控效果和降解时间的影响,寻找适合于临床应用的高效转染、低降解率的载体和应用方法。方法 应用DNA合成仪合成针对TYR的反义脱氧寡核苷酸,32P标记、脂质体包埋,加入黑色素细胞培养体系进行点杂交,行黑素含量、酪氨酸酶mRNA表达量检测以及降解时间的同位素液闪检测。结果 经脂质体包埋的反义脱氧寡核苷酸使细胞黑素含量由(64±2.3)pg/cell下降至(23±1.5)pg/cell,并可使基因表达水平由160%降低至82%;同位素液闪显示经脂质体包埋的反义脱氧寡核苷酸能使其半衰期由8 h延长至12 h。结论 脂质体可以明显增强反义核酸的调控效果,并可延长其作用半衰期。  相似文献   
4.
Objective To evaluate preliminarily the effect of HSV - tk/GCV system on gallhladder carcinoma cells in vitro.Methods Recombinant retroviral vector PLtkSN containing tk suicide gene was transfacted into gallbladder carcinoma cells, mediated by LipofectAMINETM 2000 liposome, and the growth - inhibiting rotes of GBC, SD/tk cells in the different GCV concentrations were measured by MTr methods; GBC - SD cells were mixed in the different proportions, and death rotes of the mixed cells treated with GCV were detected to verify by stander effect. Resuts GCV could lead GBC - SD/tk cells to significant death, and there was striking difference compared with the control cells (p〈0.01). When the concentration of GCV was 1,10, 50,100,500ug/ml, the killing rate of GBC - SD/tk cells was respecfively 6.8%, 2.5.2%, 54.5%, 66.3%, 89.3%, indicating dose - dependent phenomenon; With GBC - SD/tk cells in the proportion of 0, 10%, 20% ,50%, 70%, 100%, the killing rate of the mixed cells treated with GCV was 0, 19.7%, 40.3%, 77.7%, 88.0%, 93.5%, respectively. It was apparent that bystander effect was observed in the experiment. Condusion HSV - tk/GCV system could be a potential tool for the treatment of carcinoma.  相似文献   
5.
Purpose. To determine whether the non-toxic pentameric B subunit of Cholera toxin (CTB) binding to ganglioside GM1 on both the lipid vesicles and epithelial cells may provide a means to target lipid vesicles to mucosal cells expressing surface GM1. Methods. Sonicated lipid vesicles containing ganglioside GM1 were prepared. Inter-vesicle cross-linking due to pentameric CTB binding to these GM1 vesicles was determined with a sub-micron particle analyzer. Association of CTB to GM1 vesicles was analyzed with continuous sucrose gradient centrifugation. CTB-mediated binding of GM1 vesicles to human mucosal epithelial cells (Caco-2 and HT-29), mucous membranes of mouse trachea, and nasal tissues were detected with fluorescent labeled vesicles. Results. An increase in lipid particle size due to binding of CTB to lipid vesicles and inter-vesicles cross-linking was detected. At a 30-to-1 mole ratio of membrane-bound GMl-to-CTB, optimum increase in GM1 vesicle aggregation, was detected. Under such conditions, all the added CTB molecules were associated with GM1 vesicles. Time course analysis showed that inter-vesicles cross linking by CTB was detectable within 10 min. and reached a maximum value at 60 min. CTB associated GM1-vesicles bind to mucosal epithelial cells HT-29 and Caco-2 with similar affinity [Kd = 7.8 × 10–4 M lipid (Caco-2) and 7.6 × 10–4 M lipid (HT-29)]. GM1 mediated binding specificity was demonstrated by blocking with anti-GMl antibody and the insignificant degree of CTB-associated GM1 vesicle binding to GM1 deficient C6 cells. Conclusions. The CTB-mediated GM1 binding to multiple membrane surfaces provides selective localization of GM1 vesicles to GM1 expressing mucosal cells and tissues. The strategy may be useful in localizing drugs and proteins to gut and respiratory tract mucosa.  相似文献   
6.
紫杉醇诱导体外培养胃腺癌细胞系SGC-7901凋亡   总被引:2,自引:0,他引:2  
目的:研究紫杉醇对胃腺癌细胞系SGC—7901的凋亡诱导作用。方法:紫杉醇不同浓度、不同作用时间分别处理胃腺癌细胞系SGC—7901。采用MTT法测定胃癌细胞的生长抑制率,通过组织学观察、TUNEL等手段检测胃腺癌细胞系SGC--7901细胞凋亡情况。结果:紫杉醇对胃腺癌细胞系SGC—7901有明显的抑制作用,并在一定剂量和时间范围内诱导胃腺癌细胞系SGC—7901凋亡,随着药物浓度的增加及时间的延长,凋亡细胞明显增多,当紫杉醇作用浓度为20μmol/L以上时,细胞出现破碎、坏死。结论:紫杉醇对胃腺癌细胞系SGC—7901有明显的抑制作用,诱导凋亡是其发挥抗癌作用的机制之一。  相似文献   
7.
本文采用去垢剂透析法成功制备出携载SOD的脂质体(L-SOD),其直径为102nm,对SOD的包裹率为21%,90%以上酶活性存在于脂质体内部。将L-SOD注射到大鼠静脉血中,其半衰期超过4h,明显长于天然SOD(8min)。表明L-SOD优于天然SOD,具有临床应用前景。  相似文献   
8.
Intraperitoneal injection of free valproic acid (VPA) suppressed amygdaloid-kindled seizure 1 h after injection in rats, but had no effect at 24 h. VPA entrapped in positively charged liposomes showed a prolonged anticonvulsant effect lasting for 2 days, while the effect evaluated at 1 h was not different from that with free VPA. VPA entrapped in negatively charged liposomes exerted a significantly stronger effect at 1 h than did free VPA, while it had no significant effect at 24 h. These results suggest that surface charges on liposomes play an important role in modifying the anticonvulsant effect of VPA.  相似文献   
9.
The vitamin D3 derived hormone 1,25 (OH)2 vitamin D3 (1,25 D3) is able to induce growth arrest and differentiation in myelomonocytic leukaemia cells. In order to allow for specific delivery to leukaemic cells the lipophilic compound was incorporated into the lipid membranes of liposomes. Liposomal 1,25 D3 reduced proliferation as measured by 3H-thymidine incorporation in HL60 leukaemia cells by up to 60%. When liposomes were prepared at different concentrations of 1,25 D3 65% inhibition was achieved at 48 n M . The MC 1288 stereoisomer of 1,25 D3 was more potent and had the same activity at 48 n M .
The effect of the liposomal compounds was specific to myeloid cells as they reduced proliferation in myelomonocytic HL60, monoblastic U937 and monocytic Mono Mac 6 cells but not in the T-cell lines Jurkat and Molt 4.
The antiproliferative effect of liposomal 1,25 D3 was associated with an induction of differentiation since treated HL60 cells showed a monocytic morphology, increased expression of CD14 and decreased expression of CD33.
When peripheral blood leukaemic cells from M4 and M5 acute myeloid leukaemia (AML) patients were admixed with liposomal compounds an antiproliferative effect was seen in all five cases, including the two cases where free compounds led to enhanced growth. Liposomal delivery of 1,25 (OH)2 vitamin D3 may offer a novel approach to treatment of myelomonocytic leukaemia.  相似文献   
10.
Purpose. The mucoadhesiveness of polymer-coated liposomes was evaluated to develop a novel drug carrier system for oral administration of poorly absorbed drugs such as peptide drugs. Methods. Multilamellar liposomes consisting of dipalmitoylphosphatidylcholine (DPPC) and dicetyl phosphate (DCP) (DPPC:DCP = 8:2 in molar ratio) were coated with chitosan (CS), polyvinyl alcohol having a long alkyl chain (PVA-R) and poly (acrylic acid) bearing a cholesteryl group. The adhesiveness of the resultant polymer-coated liposomes to the rat intestine was measured in vitro by a particle counting method with a Coulter counter. The CS-coated liposomes containing insulin were administered to normal rats and the blood glucose level was monitored. Results. The existence of polymer layers on the surface of liposomes was confirmed by measuring the zeta potential of liposomes. The CS-coated liposomes showed the highest mucoadhesiveness and the degree of adhesion was dependent on the amount of CS on the surface of the liposomes. The blood glucose level of rats was found to be significantly decreased after administration of the CS-coated liposomes containing insulin. The lowered glucose level was maintained for more than 12h after administration of the liposomal insulin, which suggested mucoadhesion of the CS-coated liposomes in the intestinal tract of the rats.  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