全文获取类型
收费全文 | 9315篇 |
免费 | 786篇 |
国内免费 | 38篇 |
专业分类
电工技术 | 135篇 |
综合类 | 13篇 |
化学工业 | 2141篇 |
金属工艺 | 237篇 |
机械仪表 | 389篇 |
建筑科学 | 244篇 |
矿业工程 | 4篇 |
能源动力 | 402篇 |
轻工业 | 748篇 |
水利工程 | 31篇 |
石油天然气 | 4篇 |
无线电 | 1754篇 |
一般工业技术 | 1976篇 |
冶金工业 | 805篇 |
原子能技术 | 125篇 |
自动化技术 | 1131篇 |
出版年
2024年 | 13篇 |
2023年 | 91篇 |
2022年 | 153篇 |
2021年 | 227篇 |
2020年 | 187篇 |
2019年 | 235篇 |
2018年 | 313篇 |
2017年 | 248篇 |
2016年 | 364篇 |
2015年 | 307篇 |
2014年 | 411篇 |
2013年 | 667篇 |
2012年 | 501篇 |
2011年 | 654篇 |
2010年 | 512篇 |
2009年 | 528篇 |
2008年 | 521篇 |
2007年 | 412篇 |
2006年 | 379篇 |
2005年 | 315篇 |
2004年 | 304篇 |
2003年 | 264篇 |
2002年 | 245篇 |
2001年 | 221篇 |
2000年 | 194篇 |
1999年 | 206篇 |
1998年 | 317篇 |
1997年 | 235篇 |
1996年 | 182篇 |
1995年 | 133篇 |
1994年 | 114篇 |
1993年 | 80篇 |
1992年 | 60篇 |
1991年 | 59篇 |
1990年 | 60篇 |
1989年 | 54篇 |
1988年 | 37篇 |
1987年 | 46篇 |
1986年 | 49篇 |
1985年 | 33篇 |
1984年 | 26篇 |
1983年 | 29篇 |
1982年 | 8篇 |
1981年 | 20篇 |
1980年 | 20篇 |
1979年 | 11篇 |
1978年 | 13篇 |
1977年 | 18篇 |
1976年 | 25篇 |
1975年 | 10篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
Yeongin Kim Chenxin Zhu Wen-Ya Lee Anna Smith Haowen Ma Xiang Li Donghee Son Naoji Matsuhisa Jaemin Kim Won-Gyu Bae Sung Ho Cho Myung-Gil Kim Tadanori Kurosawa Toru Katsumata John W. F. To Jin Young Oh Seonghyun Paik Soo Jin Kim Lihua Jin Feng Yan Jeffrey B.-H. Tok Zhenan Bao 《Advanced materials (Deerfield Beach, Fla.)》2023,35(1):2203541
Hemispherical image sensors simplify lens designs, reduce optical aberrations, and improve image resolution for compact wide-field-of-view cameras. To achieve hemispherical image sensors, organic materials are promising candidates due to the following advantages: tunability of optoelectronic/spectral response and low-temperature low-cost processes. Here, a photolithographic process is developed to prepare a hemispherical image sensor array using organic thin film photomemory transistors with a density of 308 pixels per square centimeter. This design includes only one photomemory transistor as a single active pixel, in contrast to the conventional pixel architecture, consisting of select/readout/reset transistors and a photodiode. The organic photomemory transistor, comprising light-sensitive organic semiconductor and charge-trapping dielectric, is able to achieve a linear photoresponse (light intensity range, from 1 to 50 W m−2), along with a responsivity as high as 1.6 A W−1 (wavelength = 465 nm) for a dark current of 0.24 A m−2 (drain voltage = −1.5 V). These observed values represent the best responsivity for similar dark currents among all the reported hemispherical image sensor arrays to date. A transfer method was further developed that does not damage organic materials for hemispherical organic photomemory transistor arrays. These developed techniques are scalable and are amenable for other high-resolution 3D organic semiconductor devices. 相似文献
82.
SD Colman SA Rasmussen VT Ho CR Abernathy MR Wallace 《Canadian Metallurgical Quarterly》1996,58(3):484-490
Using loss of heterozygosity analysis, a method designed to detect moderate to large gene deletions, we have identified a new-mutation neurofibromatosis type 1 (NF1) patient who is somatically mosaic for a large maternally derived deletion in the NF1 gene region. The deletion extends at least from exon 4 near the 5' end of the gene to intron 39 near the 3' end. The gene-coding region is, therefore, mostly or entirely deleted, encompassing a loss of > or = 100 kb. We hypothesize that the deletion occurred at a relatively early developmental timepoint, since signs of NF1 in this patient are not confined to a specific body region, as seen in "segmental" NF, and since both mesodermally and ectodermally derived cells are affected. This report provides the first molecular evidence of somatic mosaicism in NF1 and, taken together with a recent report of germ-line mosaicism in NF1, adds credence to the concept that mosaicism plays an important role in phenotypic and genetic aspects of NF1 and may even be a relatively common phenomenon. 相似文献
83.
Sul Gee Park Ho Cheol Jeong Jeong Won Kim Dong-Hwan Hwang Sang Jeong Lee 《International Journal of Control, Automation and Systems》2011,9(2):276-284
This paper proposes a magnetic compass fault detection method for GPS/INS/Magnetic compass integrated navigation systems.
The fault is assumed to be caused by the hard iron and soft iron effect and modeled as an abrupt change in the magnetic compass
output. In order to detect the fault, a test statistic related with only azimuth error measurement is determined. When a fault
is detected, the GPS/INS/Magnetic compass integrated navigation system is changed into a GPS/INS integrated navigation system
mode. In order to show the validity of the proposed method, computer simulation and van testing are carried out. The simulation
and van test results show that the proposed navigation system gives more accurate outputs than the GPS/INS/Magnetic compass
without the proposed method. 相似文献
84.
Bong Seok Park Jin Bae Park Yoon Ho Choi 《International Journal of Control, Automation and Systems》2011,9(3):534-541
In this paper, an adaptive observer-based trajectory tracking problem is solved for nonholonomic mobile robots with uncertainties.
An adaptive observer is first developed to estimate the unmeasured velocities of a mobile robot with model uncertainties.
Using the designed observer and the backstepping technique, a trajectory tracking controller is designed to generate the torque
as an input. Using Lyapunov stability analysis, we prove that the closed-loop system is asymptotically stable with respect
to the estimation errors and tracking errors. Finally, the simulation results are presented to validate the performance and
robustness of the proposed control system against uncertainties. 相似文献
85.
86.
87.
88.
This paper considers the robust-optimal design problems of output feedback controllers for linear systems with both time-varying elemental (structured) and norm-bounded (unstructured) parameter uncertainties. Two new sufficient conditions are proposed in terms of linear-matrix-inequalities (LMIs) for ensuring that the linear output feedback systems with both time-varying elemental and norm-bounded parameter uncertainties are asymptotically stable, where the mixed quadratically-coupled parameter uncertainties are directly considered in the problem formulation. A numerical example is given to show that the presented sufficient conditions are less conservative than existing ones reported recently. Then, by integrating the hybrid Taguchi-genetic algorithm (HTGA) and the proposed LMI-based sufficient conditions, a new integrative approach is presented to find the output feedback controllers of the linear systems with both time-varying elemental and norm-bounded parameter uncertainties such that the control objective of minimizing a quadratic integral performance criterion subject to the stability robustness constraint is achieved. A design example of the robust-optimal output feedback controller for the AFTI/F-16 aircraft control system with the time-varying elemental parameter uncertainties is given to demonstrate the applicability of the proposed new integrative approach. 相似文献
89.
HzKR127 is the humanized monoclonal antibody effective for the neutralization of human hepatitis B virus. By means of the free energy perturbation (FEP) calculations based on molecular dynamic (MD) simulations, we examine the mutation-induced variations in the energetic and structural features associated with the interactions between HzKR127 and its antigen. N58A, Y96A, D97A, and D97A/Y102A mutants of HzKR127 are taken in account in this study for which the experimental data for relative efficacies with respect to the wild-type antibody are available. The results of the present MD-FEP simulation studies show that in order to enhance the affinity for the antigen, the engineering of HzKR127 should be made in such a way as to promote the dynamic stability of the overall protein conformation and that of the translational motion of the antigen in the antibody-antigen complex. The relative binding free energies of the four mutant antibodies obtained from MD-FEP calculations compare pretty well with the experimental mutagenesis data with the associated squared correlation coefficient of 0.96. This indicates that MD-FEP calculations may serve as a useful computational tool for rational antibody engineering. Discussed in detail are the differences in the structural features of antibody-antigen interactions between the wild-type and the mutant antibodies that are responsible for the change in binding affinities for the antigen. 相似文献
90.
Scanning laser range sensors provide range data consisting of a set of point measurements. The laser sensor URG-04LX has a
distance range of approximately 0.02–4 m and a scanning angle range of 240°. Usually, such an image range is acquired from
one viewpoint by “moving” the laser beam using rotating mirrors/prisms. The orientation of the laser beam can easily be measured
and converted into the coordinates of the image. This article conducts localization using virtual labels with data about distances
in the environment obtained from 2D distance laser sensors. This method puts virtual labels on special features and points
which are along the mobile robot’s path. The current location is calculated by combining the virtual label and the range image
of the laser range finder. 相似文献