全文获取类型
收费全文 | 7160篇 |
免费 | 944篇 |
国内免费 | 890篇 |
专业分类
化学 | 5299篇 |
晶体学 | 85篇 |
力学 | 404篇 |
综合类 | 104篇 |
数学 | 1069篇 |
物理学 | 2033篇 |
出版年
2024年 | 20篇 |
2023年 | 151篇 |
2022年 | 263篇 |
2021年 | 249篇 |
2020年 | 321篇 |
2019年 | 320篇 |
2018年 | 254篇 |
2017年 | 260篇 |
2016年 | 339篇 |
2015年 | 373篇 |
2014年 | 438篇 |
2013年 | 619篇 |
2012年 | 651篇 |
2011年 | 620篇 |
2010年 | 484篇 |
2009年 | 458篇 |
2008年 | 521篇 |
2007年 | 433篇 |
2006年 | 413篇 |
2005年 | 271篇 |
2004年 | 232篇 |
2003年 | 163篇 |
2002年 | 162篇 |
2001年 | 96篇 |
2000年 | 96篇 |
1999年 | 81篇 |
1998年 | 72篇 |
1997年 | 64篇 |
1996年 | 60篇 |
1995年 | 36篇 |
1994年 | 37篇 |
1993年 | 44篇 |
1992年 | 37篇 |
1991年 | 23篇 |
1990年 | 28篇 |
1989年 | 29篇 |
1988年 | 23篇 |
1987年 | 19篇 |
1986年 | 19篇 |
1985年 | 29篇 |
1984年 | 23篇 |
1983年 | 20篇 |
1982年 | 14篇 |
1981年 | 12篇 |
1980年 | 17篇 |
1979年 | 12篇 |
1978年 | 18篇 |
1977年 | 13篇 |
1976年 | 11篇 |
1975年 | 9篇 |
排序方式: 共有8994条查询结果,搜索用时 15 毫秒
931.
A new kind of silver micro-dendrites have been synthesized for the separation and multiplex detection of DNA merely by earth gravity. Through this approach, the DNA strands of the sickle cell disease, human T-lymphotropic virus type I, the anthrax lethal factor can be detected down to 100 pM with the detection range from 100 pM to 100 nM at the same time. 相似文献
932.
Li Z Zhu H Xie D Wang K Cao A Wei J Li X Fan L Wu D 《Chemical communications (Cambridge, England)》2011,47(12):3520-3522
We report a fast (in 10-40 s) flame synthesis of high quality few-layered graphene/graphite films, offering the advantages of simplicity, high efficiency, energy saving, low cost and the ability to extend to continuous and mass production of graphene. 相似文献
933.
Feng DQ Liu G Zheng W Liu J Chen T Li D 《Chemical communications (Cambridge, England)》2011,47(30):8557-8559
DNA-functionalized gold nanoparticles are shown to act as a light-scattering switch. Ag(+) ion turns on the switch through the DNA-Au NPs conjugates based on the formation of cytosine-Ag(+)-cytosine base pairs, whereas cysteine turns off the light-scattering signal because it competitively binds to Ag(+). 相似文献
934.
Zhang N Ouyang S Li P Zhang Y Xi G Kako T Ye J 《Chemical communications (Cambridge, England)》2011,47(7):2041-2043
Micro/mesoporous Zn(2)GeO(4) with crystalline pore-walls was successfully synthesized via a simple ion exchange method at room temperature. This structure showed enhanced activity in photoreduction of CO(2) in comparison with Zn(2)GeO(4) prepared by a solid state reaction. 相似文献
935.
Stimuli-responsive polymer hydrogels as a new class of draw agent for forward osmosis desalination 总被引:1,自引:0,他引:1
Li D Zhang X Yao J Simon GP Wang H 《Chemical communications (Cambridge, England)》2011,47(6):1710-1712
Ionic polymer hydrogels with thermal responsive units are found to induce higher water permeation rates in the osmosis process, and higher water release rates under a combination of pressure and thermal stimuli. These hydrogels have the potential for use as draw agent in forward osmosis desalination. 相似文献
936.
Prentice BM Xu W Ouyang Z McLuckey SA 《International journal of mass spectrometry》2011,306(2-3):114-122
The effects of the application of various DC magnitudes and polarities to an end-cap of a 3-D quadrupole ion trap throughout a mass spectrometry experiment were investigated. Application of a monopolar DC field was achieved by applying a DC potential to the exit end-cap electrode, while maintaining the entrance end-cap electrode at ground potential. Control over the monopolar DC magnitude and polarity during time periods associated with ion accumulation, mass analysis, ion isolation, ion/ion reaction, and ion activation can have various desirable effects. Included amongst these are increased ion capture efficiency, increased ion ejection efficiency during mass analysis, effective isolation of ions using lower AC resonance ejection amplitudes, improved temporal control of the overlap of oppositely charged ion populations, and the performance of "broad-band" collision induced dissociation (CID). These results suggest general means to improve the performance of the 3-D ion trap in a variety of mass spectrometry and tandem mass spectrometry experiments. 相似文献
937.
The incidence of Aspergillus fumigatus infections has become more frequent as a consequence of widespread immunosuppression. At present, the number of available antifungal agents in the clinic is limited, and most of them, such as itraconazole (ICZ), are toxic and show resistance. Berberine (BER) is a plant alkaloid used in the clinic mainly for alimentary infections. We have used BER and ICZ to measure in vitro resistance in A. fumigatus isolated from clinical patients. The minimum inhibitory concentration ranges of BER and ICZ were 4-256 and 0.031-0.250 μg/mL, respectively. In addition, against A. fumigatus IFM 40808 strain, the MIC?? values of BER and ICZ were 8 and 0.125 μg/mL. Using this strain, we compared the giant colonies with or without BER, and concluded that BER could restrain A. fumigatus mycelial growth and conidial pigment production. Combinations of the two drugs were also tested by the checkerboard assay to identify any functional interactions between them. Thirty-two out of 42 isolates had FICI values > 4.0, indicating that two drugs were mutually antagonistic. In conclusion, it is not advised that BER and ICZ be used in the clinic at the same time. Our results indicated that BER may inhibit A. fumigatus through the ergosterol biosynthesis pathway, like ICZ. 相似文献
938.
Xie YM Deng Y Dai XY Liu J Ouyang L Wei YQ Zhao YL 《Molecules (Basel, Switzerland)》2011,16(3):2519-2526
Twelve novel acenaphthene derivatives have been synthesized. The structures of all compounds were confirmed by 1H-NMR, MS and elemental analysis. Their antitumor activities were evaluated in six human solid tumor cell lines, namely non-small cell lung cancer (H460), human colon adenocarcinoma (SW480), human breast cancer cell (MDA-MB-468 and SKRB-3), human melanoma cell (A375) and human pancreatic cancer (BxPC-3). Among them, compound 3c shows the best antitumor activity against SKRB-3 cell line, as high as the positive control adriamycin. 相似文献
939.
Zhu J Xue M Zhao D Zhang M Duan L Qiu Y Cao T 《Angewandte Chemie (International ed. in English)》2011,50(52):12478-12482
You crack me up: A topographically patterned PDMS stamp was coated with thin metal film and swelled under organic vapor to induce the tunable cracking of the brittle film into metallic nanostructures (see SEM images, scale bars 1?μm). UV/Vis spectra, OLED efficiency, and SERS spectra demonstrate the fine controllability of the metallic nanostructures, the well-ordered and highly regulable surface plasmons, and the facile fabrication process. 相似文献
940.