全文获取类型
收费全文 | 3403篇 |
免费 | 90篇 |
国内免费 | 6篇 |
学科分类
工业技术 | 3499篇 |
出版年
2021年 | 39篇 |
2020年 | 24篇 |
2019年 | 45篇 |
2018年 | 43篇 |
2017年 | 56篇 |
2016年 | 57篇 |
2015年 | 48篇 |
2014年 | 49篇 |
2013年 | 205篇 |
2012年 | 94篇 |
2011年 | 128篇 |
2010年 | 107篇 |
2009年 | 118篇 |
2008年 | 134篇 |
2007年 | 140篇 |
2006年 | 118篇 |
2005年 | 128篇 |
2004年 | 93篇 |
2003年 | 112篇 |
2002年 | 88篇 |
2001年 | 91篇 |
2000年 | 67篇 |
1999年 | 75篇 |
1998年 | 124篇 |
1997年 | 83篇 |
1996年 | 76篇 |
1995年 | 51篇 |
1994年 | 47篇 |
1993年 | 48篇 |
1992年 | 37篇 |
1991年 | 32篇 |
1990年 | 44篇 |
1989年 | 40篇 |
1988年 | 41篇 |
1987年 | 53篇 |
1986年 | 36篇 |
1985年 | 55篇 |
1984年 | 40篇 |
1983年 | 37篇 |
1982年 | 38篇 |
1981年 | 36篇 |
1980年 | 30篇 |
1979年 | 34篇 |
1978年 | 34篇 |
1977年 | 31篇 |
1976年 | 50篇 |
1975年 | 30篇 |
1974年 | 32篇 |
1973年 | 42篇 |
1972年 | 23篇 |
排序方式: 共有3499条查询结果,搜索用时 15 毫秒
1.
Ava Kwong Cecilia Y. S. Ho Vivian Y. Shin Chun Hang Au Tsun Leung Chan Edmond S. K. Ma 《International journal of molecular sciences》2021,22(2)
The germline carrier of the BRCA1 pathogenic mutation has been well proven to confer an increased risk of breast and ovarian cancer. Despite BRCA1 biallelic pathogenic mutations being extremely rare, they have been reported to be embryonically lethal or to cause Fanconi anemia (FA). Here we describe a patient who was a 48-year-old female identified with biallelic pathogenic mutations of the BRCA1 gene, with no or very subtle FA-features. She was diagnosed with ovarian cancer and breast cancer at the ages of 43 and 44 and had a strong family history of breast and gynecological cancers. 相似文献
2.
3.
Biyun Fang Chuanfeng Zhang Zeliang Qi Chunyan Li Jun Ni Xiuyun Wang Jianxin Lin Chak-Tong Au Bingyu Lin Lilong Jiang 《American Institute of Chemical Engineers》2022,68(11):e17849
The design of an efficient non-noble metal catalyst is of burgeoning interest for ammonia synthesis. Herein, we report a Mo2C/CeO2 catalyst that is superior in ammonia synthesis activity. In this catalyst, molybdenum carbide coexisted with the ceria overlayers which is from the ceria support as the strong metal–support interaction. There is a high proportion of low-valent Mo species, as well as high concentration of Ce3+ and surface oxygen species. The presence of Mo2C and CeO2 overlayers not only leads to enhancement of hydrogen and nitrogen adsorption, but also facilitates the desorption and exchange of adsorbed species with the gaseous reagents. Compared with the Mo/CeO2 catalyst prepared without carbonization, the Mo2C/CeO2 catalyst is more than sevenfold higher in ammonia synthesis rate. This work not only presents an explicit example of designing Mo-based catalyst that is highly efficient for ammonia synthesis by tuning the adsorption and desorption properties of the reactant gases, but opens a perspective for other elements in ammonia synthesis. 相似文献
4.
5.
Systematic assessment of anger among people with developmental disabilities has been lacking, especially for hospital inpatients. Reliability and validity of anger self-report psychometric scales were investigated with 129 male patients, mostly forensic. Anger prevalence and its relationship to demographic, cognitive, and personality variables and to hospital assaultive behavior were examined. High internal and intermeasure consistency, and some concurrent validity with staff ratings, were found. Retrospective validity regarding physically assaultive behavior in the hospital was obtained. Hierarchical regressions revealed that patient-reported anger was a significant predictor of assaults postadmission, controlling for age, length of stay, IQ, violence offense history, and personality variables. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
6.
Moss C.D. Teixeira F.L. Yang Y.E. Jin Au Kong 《Geoscience and Remote Sensing, IEEE Transactions on》2002,40(1):178-186
A three-dimensional (3D) finite-difference time-domain (FDTD) scheme is introduced to model the scattering from objects in continuous random media. FDTD techniques have been previously applied to scattering from random rough surfaces and randomly placed objects in a homogeneous background, but little has been done to simulate continuous random media with embedded objects where volumetric scattering effects are important. In this work, Monte Carlo analysis is used in conjunction with FDTD to study the scattering from perfectly electrically conducting (PEC) objects embedded in continuous random media. The random medium models under consideration are chosen to be inhomogeneous soils with a spatially fluctuating random permittivities and prescribed correlation functions. The ability of frequency averaging techniques to discriminate objects in this scenarion is also briefly investigated. The simulation scheme described in this work can be adapted and used to help in interpreting the scattered field data from targets in random environments such as geophysical media, biological media, or atmospheric turbulence 相似文献
7.
Hannes Verlinde Martine De Cock Raymond Boute 《IEEE transactions on systems, man, and cybernetics. Part B, Cybernetics》2006,36(3):679-684
As opposed to quantitative association rule mining, fuzzy association rule mining is said to prevent the overestimation of boundary cases, as can be shown by small examples. Rule mining, however, becomes interesting in large databases, where the problem of boundary cases is less apparent and can be further suppressed by using sensible partitioning methods. A data-driven approach is used to investigate if there is a significant difference between quantitative and fuzzy association rules in large databases. The influence of the choice of a particular triangular norm in this respect is also examined. 相似文献
8.
Values of D0 /δ and Q for grain-boundary diffusion, derived from published studies of normal grain growth in Al2 O3 , BeO, CaO, MgO, SiO2 , and CaSiO3 , are fit by the linear compensation equation log D0 /δ=0.03170Q -7.6792 (r2 =0.9384). Comparison of grain-boundary diffusion coefficients derived from grain growth in oxides with those obtained by direct experimental measurement suggests that the kinetics of normal grain growth are controlled by grain-boundary diffusion of oxygen. 相似文献
9.
In this paper we shall review the main appraches to nonmonotonic reasoning which we classify from the perspective of their underlying logical settings as classical, intuitionistic, three-valued/partial models, and conditional. We shall be placing special emphasis on some of the prominent approaches. We shall also give hints on potential future directions and emphasize that more theoretical work is still needed before a move to application is made. 相似文献
10.