全文获取类型
收费全文 | 9092篇 |
免费 | 728篇 |
国内免费 | 529篇 |
专业分类
化学 | 2110篇 |
晶体学 | 14篇 |
力学 | 1112篇 |
综合类 | 78篇 |
数学 | 1255篇 |
物理学 | 1428篇 |
无线电 | 4352篇 |
出版年
2024年 | 23篇 |
2023年 | 90篇 |
2022年 | 178篇 |
2021年 | 234篇 |
2020年 | 277篇 |
2019年 | 181篇 |
2018年 | 173篇 |
2017年 | 317篇 |
2016年 | 425篇 |
2015年 | 385篇 |
2014年 | 559篇 |
2013年 | 600篇 |
2012年 | 593篇 |
2011年 | 659篇 |
2010年 | 503篇 |
2009年 | 519篇 |
2008年 | 509篇 |
2007年 | 538篇 |
2006年 | 519篇 |
2005年 | 424篇 |
2004年 | 428篇 |
2003年 | 366篇 |
2002年 | 296篇 |
2001年 | 207篇 |
2000年 | 187篇 |
1999年 | 153篇 |
1998年 | 144篇 |
1997年 | 139篇 |
1996年 | 127篇 |
1995年 | 115篇 |
1994年 | 83篇 |
1993年 | 66篇 |
1992年 | 47篇 |
1991年 | 44篇 |
1990年 | 36篇 |
1989年 | 18篇 |
1988年 | 27篇 |
1987年 | 24篇 |
1986年 | 16篇 |
1985年 | 19篇 |
1984年 | 15篇 |
1982年 | 16篇 |
1981年 | 6篇 |
1980年 | 7篇 |
1979年 | 14篇 |
1978年 | 8篇 |
1977年 | 8篇 |
1976年 | 11篇 |
1974年 | 4篇 |
1973年 | 3篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
201.
Paul P. Dillon Stephen J. Daly Anthony J. Killard Richard O'kennedy 《International journal of environmental analytical chemistry》2013,93(7-8):525-543
The interaction between antibody and antigen is characterised by relatively high affinity and specificity, making this type of reaction a prime candidate for use as an analytical tool. The interaction may be combined with biosensors in the production of immunosensors for environmental monitoring. Polyclonal and monoclonal antibodies have had a significant impact in analytical detection systems over the past few decades with antibody fragments becoming important in recent years. Production of antibodies to small haptens requires the initial conjugation of hapten to a larger carrier molecule. Once hapten-carrier conjugates have been produced, polyclonal, monoclonal and various antibody fragments may be produced by differing protocols. A critical step in the production of antibody fragments is the development of efficient screening procedures to identify suitable antibody-producing clones and this has been reviewed in this article. Various antibody types may then be used in the generation of immunosensors for the monitoring of environmental pollutants. The selection of the appropriate sensor technology applicable for the determination of an antibody-antigen interaction is of prime importance for immunosensor development. One example of such an application is surface plasmon resonance-based biosensors, as they provide real-time analysis of interactions between the antibody and antigen of interest. 相似文献
202.
Wen Dan Xuankai Deng 《International journal of environmental analytical chemistry》2013,93(15):1515-1527
ABSTRACTIn this work, a new turn-on fluorescent probe 1 for Hg2+ ions detection based on rhodamine B spirolactam was reported. Among tested metal ions, probe 1 shows high selectivity towards Hg2+ in the the mixture solution of methanol and 0.02 M HEPES buffer (V/V = 9:1, pH = 7.2). No absorption and emission band of probe 1 was observed in the range from 450 to 700 nm. While only addition of Hg2+ to probe 1 could lead to appearance of a new absorption band centered at 553 nm and a fluorescence emission band around 577 nm upon excitation at 520 nm. Moreover, it exhibits excellent linear relationship (R2 = 0.9993) between fluorescence intensity at 577 nm and the concentration of Hg2+ from 1.6 to 32 μM. The sensing mechanism was proven to be spirolactam ring open induced by Hg2+ through 1H NMR, MS, absorption and fluorescence spectra. In addition, probe 1 could detect Hg2+ in real water samples and on filter paper, which demonstrates its application in environment science. 相似文献
203.
204.
205.
《Microelectronics Reliability》2014,54(9-10):1887-1890
In the automotive semiconductor industry, risk assessments are requested by customers on quality incidents that happen in the assembly line or in field. More rarely, in a die business context, such a study is requested about a defect observed during the optical inspection performed by the customers on the known good dice after assembly. This article deals with the case of pin holes in the top metal surface of a MOSFET component. The risk assessment is addressing detection, occurrence and severity of the defect: this implies process and failure analysis. Also, reliability has been carried out, by completing accelerated and typical stress tests. 相似文献
206.
207.
The current leak tests for gloves are qualitative. The developed quantitative leak test uses vacuum pressure to draw measured volumes of water to detect microholes/tears in whole gloves and glove pieces. A modified plastic vacuum desiccator interfaced with a Frazier air permeability tester allowed exposure of disposable unsupported/unlined/powderless Kimtech Blue nitrile to 50 mL of water for glove pieces or to 600 mL within a whole glove at vacua of 8–9 in. (20–23 cm) and 11–12 in. (28–30 cm) water gauge, respectively. Punctures of known dimensions were made before testing in specific glove areas using 21-, 22-, 26-, 30-, and 33-gauge needles (outer/inner diameters in micrometres of 873/514, 794/413, 635/311, 476/127, 318/159 and 238/133, respectively). The length of the punctures varied from 0.13 ± 0.01 to 0.80 ± 0.11 mm. Flow rates of water through the holes/tears ranged from 2.5 ± 0.4 to 106 ± 7 mL/min for glove pieces. For whole gloves, the ranges were from 31 ± 9 to 543 ± 110 mL/min in the palm area; and 0.23 ± 0.06 to 82 ± 18 mL/min in the finger/fingertip area. The method quantified tear lengths as short as 0.13 ± 0.01 mm. 相似文献
208.
Multiaxial mechanical behavior of aramid fibers and identification of skin/core structure from single fiber transverse compression testing 下载免费PDF全文
Judith Wollbrett‐Blitz Sébastien Joannès Rémi Bruant Christophe Le Clerc Marc Romero De La Osa Anthony Bunsell Alba Marcellan 《Journal of Polymer Science.Polymer Physics》2016,54(3):374-384
The transverse and longitudinal mechanical properties of aramid fibers like Kevlar? 29 (K29) fibers are strongly linked to their highly oriented structure. Mechanical characterization at the single fiber scale is challenging especially when the diameter is as small as 15 µm. Longitudinal tensile tests on single K29 fibers and single fiber transverse compression test (SFTCT) have been developed. Our approach consists of coupling morphological observations and mechanical experiments with SFTCT analysis by comparing analytical solutions and finite element modeling. New insights on the analysis of the transverse direction response are highlighted. Systematic loading/unloading compression tests enable to experimentally determine a transverse elastic limit. Taking account of the strong anisotropy of the fiber, the transverse mechanical response sheds light on a skin/core architecture. More importantly, results suggest that the skin of the fiber, typically representing a shell of one micrometer in thickness, has a transverse apparent modulus of 0.2 GPa. That is around more than fifteen times lower than the transverse modulus of 3.0 GPa in the core. By comparison, the measured longitudinal modulus is about 84 GPa. The stress distribution in the fiber is explored and the critical areas for damage initiation are discussed. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2016 , 54, 374–384 相似文献
209.
Brownian distance correlation-directed search: A fast feature selection technique for alternate test
Machine-learning indirect test relies on powerful statistical algorithms to build prediction models that relate cheap measurements to costly performance metrics. Though many works in the past have been focused on proposing different models or on ways to improve the reliability of the results, it appears that the main bottleneck of the approach is the definition of an information-rich input space. Finding the appropriate measurements that are both cheap and meaningful is a task that has not yet been automated. In this framework, feature selection is a necessary tool to explore possible candidates. In this paper a hybrid method is proposed that lay between filtering and wrapper-based methods, trying to strike the right balance between accuracy and speed for the particular case of Alternate Test. 相似文献
210.
Flexible aluminum moisture barrier films are shown to meet ultra-barrier requirements with water vapor transmission rates as low as 1*10−4 g/m2/day at 38 °C and 90% R.H. These low transmission rates are achieved by lamination of two films that are independently processed on individual substrates. The integration in organic electronic devices like organic solar cells or OLEDs is particularly easy in a single lamination step, since an existing aluminum electrode can be utilized as one half of the moisture barrier. The resulting laminate maintains flexibility of the device and improves the barrier quality by an order of magnitude compared to conventional stacking of two barriers. Organic solar cells with this type of encapsulation are manufactured and aged in controlled climate. They do not exhibit significant extrinsic degradation. 相似文献