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   32013篇
  免费   2923篇
  国内免费   2393篇
耳鼻咽喉   235篇
儿科学   260篇
妇产科学   332篇
基础医学   3768篇
口腔科学   490篇
临床医学   4714篇
内科学   4661篇
皮肤病学   255篇
神经病学   1722篇
特种医学   1073篇
外国民族医学   21篇
外科学   2921篇
综合类   5451篇
现状与发展   5篇
一般理论   2篇
预防医学   1822篇
眼科学   1197篇
药学   3578篇
  26篇
中国医学   1906篇
肿瘤学   2890篇
  2024年   116篇
  2023年   569篇
  2022年   1490篇
  2021年   1780篇
  2020年   1365篇
  2019年   1224篇
  2018年   1131篇
  2017年   1163篇
  2016年   1003篇
  2015年   1591篇
  2014年   1854篇
  2013年   1530篇
  2012年   2341篇
  2011年   2553篇
  2010年   1522篇
  2009年   1187篇
  2008年   1579篇
  2007年   1560篇
  2006年   1610篇
  2005年   1820篇
  2004年   996篇
  2003年   857篇
  2002年   783篇
  2001年   674篇
  2000年   652篇
  1999年   763篇
  1998年   543篇
  1997年   502篇
  1996年   390篇
  1995年   369篇
  1994年   302篇
  1993年   212篇
  1992年   233篇
  1991年   212篇
  1990年   191篇
  1989年   143篇
  1988年   146篇
  1987年   106篇
  1986年   101篇
  1985年   66篇
  1984年   29篇
  1983年   24篇
  1982年   11篇
  1981年   19篇
  1980年   9篇
  1979年   8篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
11.
In order to investigate the antagonistic effect of Glycyrrhiza Uralensis Fish (GUF) and Chelidonium maJus L (CML) on gastrccarcinogenesis induced by MNNG in Wastar rats, we treated the rats with MNNG alone (group 1) and with MNNG plus GUF and CML (group 2 and 3) respectively. The incidence of infiltrating adenocarcinoma of the glandular stomach and duodenum in group 2 was significantly lower than that in group 1 (26.7% vs. 67.8%). The differentiation and aggressivenees of carcinomas occured in group 2 were much better and mild than those in group 1. Present study also demonstrated that the inhibitory effect of CML on proliferation of human stomach carcinoma cell line MGC-803 was very remarkable; in addition, GUF and CML were able to antagonise the mutagenic activation of MNNG. These results suggest that GUF and CML may be empoyed in prevention of gastric carcinoma.  相似文献   
12.
永瓣藤化学成分的研究   总被引:2,自引:1,他引:1  
永瓣藤化学成分的研究陈玲,谢平,戚薇,曾菊珍(药学系中药化学教研室)关键词永瓣藤,化学成分,三萜,蒜盘子甾酮永瓣藤(MonimopetalnmChinenseRe-hd)系卫矛科永瓣藤属植物[1],为我国特有的珍稀二类保护植物[2],分布于江西东北部...  相似文献   
13.
目的 :探讨地塞米松减轻曲马多术后镇痛时恶心呕吐的临床效果。方法 :选择术后自愿硬膜外镇痛(PCEA)的病例 6 0例 ,随机分为试验组 (地塞米松 曲马多 0 .15 %布比卡因 )和对照组 (格拉司琼 曲马多 0 .15 %布比卡因 )。结果 :两组病人术后疼痛评分 (VAS法 ) ,镇静评分及恶心呕吐的发生率无明显差异 (P >0 .0 5 )。结论 :地塞米松可以减轻曲马多术后镇痛时恶心呕吐的发生 ,效果良好 ,不增加副作用 ,价格便宜  相似文献   
14.
本研究用酶联免疫吸附术观察8只家兔在附睾注射鱼肝油酸钠后血清及精浆中的抗精子抗体。血清抗精子抗体阳性率为37.5~50.0%,最早检出率为术后2个月,6~7月达高峰。精浆抗精子抗体阳性率为25%,最早检出率为术后4个月,且此时己达高峰。与输精管结扎资料相比,发现血清抗精子抗体检出率偏低,而精浆相应抗体偏高,表明向附睾注射鱼肝油酸钠引起的免疫反应有别于结扎,以生殖道局部为主。  相似文献   
15.
Q Chen  P Sun  I Prigione  H Xie  S Ferrini 《Tumori》1992,78(2):79-86
In an attempt to construct bispecific monoclonal antibodies (bimAbs) able to target cytotoxic T lymphocytes against human hepatoma cells, an HGPRT-deficient mutant of the Hepama-6 hybridoma, which produces an antihuman-hepatoma mAb, was directly fused with splenocytes from Balb/C mice immunized by a polyclonal cytotoxic T-cell line. Hybrid hybridomas were selected in HAT medium, and their supernatants were directly screened for the ability to induce IL-2-cultured cytotoxic T lymphocytes to kill hepatoma cells in a 51Cr-release assay. The selected hybrid hybridoma, termed DQ-33, secretes a bimAb, which reacts with a CD3-associated determinant. When resting peripheral-blood lymphocytes were used as effector cells, virtually no cytolytic activity could be induced by DQ-33, whereas phytohemagglutinin-activated lymphocytes that had been expanded in vitro in IL-2-containing medium could be efficiently targeted against hepatoma cells. Targeting by DQ-33 bimAb was analyzed on different subsets of IL-2-cultured lymphocytes. It was evident that CD+4-8+ TCR alpha/beta+ and CD3+4-8-TCR gamma/delta+ lymphocytes were efficiently induced by bimAb to lyse human hepatoma cells, whereas no induction of cytolysis could be observed when CD3 + 4 + 8-TCR alpha/beta+ cells were used as effectors. DQ-33 bimAb was also able to induce lymphokine secretion (IL-2, GM-CSF and TNF-alpha) by all the different subsets of lymphocytes analyzed in the presence of target cells expressing the relevant antigen, independent of the expression of cytolytic activity.  相似文献   
16.
OBJECTIVE: To study the expression of S100 in oral submucose fibrosis(OSF). METHODS: Immunohistochemistry assay was performed on 10 cases of OSF, 10 cases of oral epithelial dysplasia (OED) and 8 cases of normal oral epithelium using monoclonal antibody against S100 protein. RESULTS: S100 did not express in the normal oral muscosal epithelium. The S100 positive nuclear staining was found in 50% of the OSF and OED cases, which was significantly higher than that in the normal oral epithelium (P < 0.05). But the positive staining in the OSF and OED cases had no difference (P > 0.05). CONCLUSION: S100 expression is closely related to the development of OSF and OED. The positive staining expression in the OSF and OED cases is the same.  相似文献   
17.
作者通过内窥镜对新疆奎屯地区氟中毒患者35名,氟砷中毒患者32名,对照组25名的胃粘膜进行观察,旨在了解氟元素和砷元素对胃粘膜的影响,在3个组中慢性胃炎的炎症程度与炎症活动性有显著性差异。2个中毒组间无显著性差异。结果表明在高氟区和高氟砷区患者的胃粘膜层病理改变主要是任性氟中毒引起,单纯性砷中毒并无协同作用。  相似文献   
18.
Pathways and enzymes of fatty acid synthase-mediated, long-even-chain (generally C16-C20) fatty acid synthesis are well studied, and general metabolism involved in short-chain (C4-C7) fatty acid biosynthesis is also understood. In contrast, mechanisms of medium-chain (C8-C14) fatty acid synthesis are unclear. Recent work suggests involvement of chain-elongation-terminating thioesterases in medium-chain fatty acid formation in oilseeds and animals. We have shown that iso- and anteiso-branched and straight, odd- and even-length, short-chain fatty acids esterified in plant-trichome-gland-produced sucrose esters are synthesized by using carbon skeletons provided by modified branched-chain amino acid metabolism/catabolism. The principal enzymes involved are those catalyzing leucine biosynthesis in all organisms and those leading to short-chain alcohols in mutant yeasts and alkyl acids in Clostridium species (products often serving as mammalian pheromones). Here we provide evidence that C10-C12 straight medium-chain and C10-C12 branched medium-chain acyl acids of tomato, C6-C8 straight-chain acyl acids of Petunia, and C6 and C8 branched acyl acids of Nicotiana glutinosa are formed by alpha-ketoacid elongation without participation of fatty acid synthase-mediated reactions or -independent thioesterases. This different metabolism suggests greater integration of amino acid and fatty acid metabolism than previously considered and provides other avenues to study and manipulate not only straight even-length but also odd- and even-length straight and branched medium-chain fatty acid biosynthesis.  相似文献   
19.
提要报告了55例儿童桡骨骨折,观察发现该病挠骨头变位情况并不完全一致,据此提了分为外侧型、外后侧型和外前侧型3型的新的分型方法。采用相应整复手法,提高了复位满意率。本组优良率达85%,其中外侧型复位较易,优良率为93%;外后侧型次之;外前侧型复位困难,优良率为70%。  相似文献   
20.
survivin与nmp22对诊断尿路上皮肿瘤价值的比较   总被引:2,自引:0,他引:2  
目的 :评价尿脱落细胞中survivin的表达和尿nmp2 2的表达对诊断尿路上皮肿瘤的价值。 方法 :对4 8例尿路上皮肿瘤患者 ,在行膀胱镜检查或手术前留新鲜尿液分别行尿脱落细胞survivin、尿nmp2 2和尿脱落细胞检查 ,并分别比较各方法的敏感性、特异性。结果 :尿路上皮肿瘤患者尿脱落细胞涂片中survivin表达 4 8例中4 6例阳性 ,尿NMP2 2有 38例阳性 ,而尿脱落细胞学仅 15例阳性 ,survivin的敏感性高于nmp2 2及脱落细胞学 (P <0 .0 5及P <0 .0 1)。三者的特异性分别为 10 0 %、90 %和 10 0 % ,差异无统计学意义。结论 :检测尿脱落细胞中survivin的表达方法简单无创敏感性、特异性高对诊断尿路上皮肿瘤的价值优于尿nmp2 2。  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