全文获取类型
收费全文 | 85413篇 |
免费 | 1039篇 |
国内免费 | 411篇 |
专业分类
电工技术 | 789篇 |
综合类 | 2320篇 |
化学工业 | 11860篇 |
金属工艺 | 4816篇 |
机械仪表 | 3058篇 |
建筑科学 | 2192篇 |
矿业工程 | 567篇 |
能源动力 | 1153篇 |
轻工业 | 3686篇 |
水利工程 | 1276篇 |
石油天然气 | 365篇 |
武器工业 | 1篇 |
无线电 | 9391篇 |
一般工业技术 | 16822篇 |
冶金工业 | 2673篇 |
原子能技术 | 290篇 |
自动化技术 | 25604篇 |
出版年
2023年 | 22篇 |
2022年 | 78篇 |
2021年 | 104篇 |
2020年 | 74篇 |
2019年 | 67篇 |
2018年 | 14499篇 |
2017年 | 13419篇 |
2016年 | 10017篇 |
2015年 | 645篇 |
2014年 | 327篇 |
2013年 | 328篇 |
2012年 | 3263篇 |
2011年 | 9558篇 |
2010年 | 8347篇 |
2009年 | 5622篇 |
2008年 | 6845篇 |
2007年 | 7859篇 |
2006年 | 193篇 |
2005年 | 1268篇 |
2004年 | 1193篇 |
2003年 | 1215篇 |
2002年 | 600篇 |
2001年 | 117篇 |
2000年 | 194篇 |
1999年 | 77篇 |
1998年 | 77篇 |
1997年 | 49篇 |
1996年 | 51篇 |
1995年 | 20篇 |
1994年 | 24篇 |
1993年 | 18篇 |
1992年 | 20篇 |
1991年 | 28篇 |
1988年 | 11篇 |
1969年 | 24篇 |
1968年 | 43篇 |
1967年 | 33篇 |
1966年 | 42篇 |
1965年 | 45篇 |
1964年 | 11篇 |
1963年 | 28篇 |
1962年 | 22篇 |
1961年 | 18篇 |
1960年 | 30篇 |
1959年 | 35篇 |
1958年 | 39篇 |
1957年 | 36篇 |
1956年 | 34篇 |
1955年 | 63篇 |
1954年 | 68篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
We constructed a probabilistic simulator that allows all the events in population dynamics such as death, birth, mutation,
and suppression/stimulation to be described by probabilistic rules. The simulator also facilitates a lattice used for expressing
distribution and diversity (number of distinct strains) of quasispecies. The simulator is used to investigate the diversity
threshold in HIV and T-cell interaction.
This work was presented in part at the 13th International Symposium on Artificial Life and Robotics, Oita, Japan, January
31–February 2, 2008 相似文献
82.
83.
Chun Lin Ma Qing Feng Wang Rufen Zhang Jikun Li 《Journal of Inorganic and Organometallic Polymers and Materials》2008,18(2):229-235
Six triorganotin(IV) complexes of the type {(R3Sn)2[C3S3(COO)2]}n (R = C6H5 1; n-Bu 2; PhCH2 4; p-F-PhCH2 5; o-F-PhCH2 6) and {(R3Sn)2[C3S3(COO)2]}n·[EtOH] (R = Me 3) have been synthesized by the reaction of bis(carboxymethyl)trithiocarbonate with triorganotin(IV) chloride
in the presence of sodium ethoxide. All complexes were characterized by elemental analysis IR, 1H, 13C and 119Sn NMR spectroscopy. Except for 4–6, all complexes were also characterized by X-ray crystallography. The X-ray date revealed
that complexes 1–3 show two-dimensional network polymeric structure in which the geometries of tin atoms are trigonal bipyramid
with the axial positions occupied by carboxylic oxygen atoms. 相似文献
84.
Veysel T. Yilmaz Evrim Senel Canan Kazak 《Journal of Inorganic and Organometallic Polymers and Materials》2008,18(3):407-413
The reaction of [Cu(sac)2(H2O)4] · 2H2O with 2-methylpyrazine (mpyz) leads two complexes, concomitant crystallization of a mononuclear complex [Cu(sac)2(mpyz)(H2O)2] (1) and a polymeric complex [Cu(sac)2(μ-mpyz)]n (2). Both complexes have been characterized by elemental analyses, magnetic measurements, FT-IR and ESR, TG-DTA and single-crystal
X-ray diffraction analyses. Single-crystal X-ray analyses show that complex 1 consists of discrete molecules in which the copper(II) ions exhibits a square-pyramidal coordination geometry. The individual
molecules of 1 are connected into a hydrogen-bonded chain structure, which is further assembled to form a three-dimensional network by π–π stacking interactions.
Complex 2 is an 1D coordination polymer in which copper(II) centers are bridged by the mpyz ligand. The chains are further assembled
to form two-dimensional frameworks by π–π and C–H···π stacking interactions. 相似文献
85.
86.
87.
88.
Rudolf Felix 《Soft Computing - A Fusion of Foundations, Methodologies and Applications》2008,12(2):129-135
Real world applications of a decision model of relationships between goals based on fuzzy relations are presented. In contrast
to other approaches the relationships between decision goals or criteria for each decision situation are represented and calculated
explicitly. The application fields are decision making for financial services and optimization of production sequences in
car manufacturing. 相似文献
89.
90.
Wenying Wei Zhen Wang Yanhua Yin Jinyu Han Wen Xu 《Korean Journal of Chemical Engineering》2008,25(3):562-567
Composition Group Vector Space (CGVS) method for estimating melting and boiling point T
m
, T
b
of organic compound has been proposed, and the principle of this method has been elucidated. The models for estimating T
m
, T
b
have been established and the numerical values of relative parameters have been presented. The average percentage deviations
of T
m
, T
b
estimation are 7.53 and 1.58, respectively, which show that the present method demonstrates significant improvement in applicability
to predict the above properties, compared to conventional group methods. 相似文献