全文获取类型
收费全文 | 2621篇 |
免费 | 43篇 |
国内免费 | 55篇 |
专业分类
教育 | 1826篇 |
科学研究 | 382篇 |
各国文化 | 11篇 |
体育 | 232篇 |
综合类 | 207篇 |
文化理论 | 4篇 |
信息传播 | 57篇 |
出版年
2024年 | 1篇 |
2023年 | 7篇 |
2022年 | 29篇 |
2021年 | 65篇 |
2020年 | 63篇 |
2019年 | 45篇 |
2018年 | 24篇 |
2017年 | 19篇 |
2016年 | 28篇 |
2015年 | 65篇 |
2014年 | 141篇 |
2013年 | 161篇 |
2012年 | 193篇 |
2011年 | 232篇 |
2010年 | 184篇 |
2009年 | 165篇 |
2008年 | 191篇 |
2007年 | 176篇 |
2006年 | 167篇 |
2005年 | 153篇 |
2004年 | 122篇 |
2003年 | 121篇 |
2002年 | 109篇 |
2001年 | 61篇 |
2000年 | 47篇 |
1999年 | 27篇 |
1998年 | 21篇 |
1997年 | 18篇 |
1996年 | 15篇 |
1995年 | 8篇 |
1994年 | 10篇 |
1993年 | 10篇 |
1992年 | 7篇 |
1991年 | 4篇 |
1990年 | 3篇 |
1989年 | 7篇 |
1987年 | 1篇 |
1985年 | 4篇 |
1984年 | 3篇 |
1983年 | 1篇 |
1982年 | 5篇 |
1981年 | 3篇 |
1979年 | 1篇 |
1978年 | 1篇 |
1977年 | 1篇 |
排序方式: 共有2719条查询结果,搜索用时 15 毫秒
941.
鉴于当前化妆品的发展趋势 ,对“四合一”珠光香波的配方组成 ,工艺流程 ,制造技术等进行了研究 ,并讨论了一些特殊添加剂的应用 相似文献
942.
INTRODUCTION S.coelicolor as a model system has been ex-tensively studied with the aid of genetic and mo-lecular techniques. Its ability to produce four anti-biotics (Hopwood et al., 1995), namely actinorhodin (Act), undecylprodigiosin (Red), Calcium-Depend- ent Antibiotic (CDA) and methylenomycin (Mmy), enables studies of pathyway-specific and pleiotropic regulation of antibiotic production. In which, Red is a red-pigmented antibiotic and Act is coelicolor- pigmented antibiotic tha… 相似文献
943.
Qiu-ping Xie Cheng Xiang Gang Wang Ke-feng Lei Yong Wang 《Journal of Zhejiang University. Science. B》2016,17(5):361-366
In various studies, metastasis associated with colon cancer 1 (MACC1) has been frequently reported to be abnormally highly expressed in human lung cancer, colon cancer, and hepatocellular carcinoma. Our study focuses on the association of MACC1 expression with gastric cancer (GC). During our experiment, the MACC1 expression was tested in 105 GC samples using an immunohistochemical (IHC) method. The clinical characteristics and prognosis of these patients were summarized. During analysis, MACC1 distribution in GC samples with distant metastasis was higher than that in normal samples and in tumors with no dissemination. Subsequently, a lower 5-year survival rate had a strong correlation with high MACC1 expression. As a consequence, the present results suggest that MACC1 is more frequently expressed in a poor prognosis phenotype of GC and acts as a promising prognostic prediction parameter for GC. 相似文献
944.
本文在链烷烃的分子图的基础上,切断分子图的任一条边(C-C键)成两个子图,以切断边的顶点为起点,对这两个子图的路径顶点数Nc(即子图中任一顶点到起始顶点这一路径中所包含的顶点数)的平方倒数求和(∑1N2c)然后进一步构造出两类新的拓扑指数———邻接矩阵特征根(X1cc,X2cc),距离积方根连接性指数和(Xc);同时,本文探讨了这些指数与相应链烷烃的原子化热(HA)的关系,结果表明本文所提出的拓扑指数与相应的链烷烃的原子化热(HA)具有良好的结构———性质相关性. 相似文献
945.
卢红敏 《淮南师范学院学报》2004,6(6):57-60
有着“中国第一才女“美誉的林擞因,是后期新月诗派的重要作家之一.林擞因的诗作上接我国的诗词传统,外应世界诗艺潮流,融中国传统诗学与西方现代诗艺于一妒,体现出古典与现代的双重色彩,呈现出独特的艺术特色,取得了较高的艺术成就. 相似文献
946.
Three cases of whiplash shaking injury of infants are presented. All children presented with seizures and had minimal signs of external injury. Examination of the retina revealed extensive retinal hemorrhages. These were missed on initial examination and were only discovered after pupillary dilatation. The presence of these palecentered retinal hemorrhages suggested the diagnosis of child abuse and skeletal surveys and thorough social histories confirmed the diagnosis. Despite extensive retinal hemorrhages, computerized axial tomography (C.T.) scan showed minimal inter-hemispheric bleeding. In contrast to the "Battered Child Syndrome," all the findings in whiplash shaking syndrome of infants are subtle and demand an awareness, an index of suspicion and a thorough examination which may include extensive retinal examination following dilatation of the pupils. This latter examination is frequently not performed by family physicians and residents so that the syndrome may be missed. A fourth case is also discussed where shaking is admitted on initial presentation but said to be done for resuscitation. This poses an immense diagnostic dilemma to the pediatrician since in this case the child presented later with all the signs of physical abuse. 相似文献
947.
以AB DF1串口控制协议为例,说明了利用CDMA/GPRS DTU传输串口数据和组建无线远程控制系统(SCADA)的基本方法.对系统组建所涉及的软硬件环境进行了介绍,并详细描述了DF1控制协议的分析过程和将其与DTU开发包集成以实现新的通讯驱动的原理.通过此类原理,我们可以实现在统一的软件构架下,通过加载所需的通讯驱动,与包含不同用户设备的RTU进行通讯,而这样的RTU,均是采用DTU为其通讯手段. 相似文献
948.
A rice mutant with Japonica 9522 cultivar background Oryza sativa extraordinary glume 1 (Oseg 1) was identified from the M2 mutant pool mutagenized by ~(60)Coγ-ray.Compared with wild type plants,Ose9 1 developed longer empty glumes and rudimentary glumes.In some Oseg 1 mutants,the number of stamens of flowers was reduced and leaf-like lodicules occurred,and excessive lemma/palea-like organ could be observed in some mutant spikelets.This indicated that OsEG1 could regulate the development of rudimentary glumes,empty glumes,lemma/palea,lodicules,and stamens.Genetic analysis indicated that Oseg 1 came from a single recessive genetic locus.To clone OsEG1 gene,F_2 population was constructed by a cross between Ose9 1(Japonica)and Guangluai4(Indica).Using map-based cloning approach,OsEG1 was mapped on chromosome 4,between INDEL marker OS407 and WHM0466 with genetic distance of 2.0 cm and 1.0 cm,respectively.These results are useful for further cloning and functional analysis of the OsEG1 gene. 相似文献
949.
介绍了基于usb2.0协议的实时视频图像采集系统。给出了该系统的硬件组成原理及软件设计方法。主要介绍了采样控制器的设计。这种设计具有功能集成度高,实现方便的优点。具有较高的实用推广价值。 相似文献
950.