全文获取类型
收费全文 | 6077篇 |
免费 | 123篇 |
国内免费 | 16篇 |
专业分类
化学 | 4407篇 |
晶体学 | 66篇 |
力学 | 72篇 |
综合类 | 1篇 |
数学 | 250篇 |
物理学 | 1420篇 |
出版年
2022年 | 44篇 |
2021年 | 69篇 |
2020年 | 79篇 |
2019年 | 77篇 |
2018年 | 55篇 |
2017年 | 47篇 |
2016年 | 92篇 |
2015年 | 97篇 |
2014年 | 103篇 |
2013年 | 254篇 |
2012年 | 246篇 |
2011年 | 306篇 |
2010年 | 146篇 |
2009年 | 159篇 |
2008年 | 296篇 |
2007年 | 305篇 |
2006年 | 303篇 |
2005年 | 319篇 |
2004年 | 309篇 |
2003年 | 211篇 |
2002年 | 211篇 |
2001年 | 191篇 |
2000年 | 175篇 |
1999年 | 98篇 |
1998年 | 49篇 |
1997年 | 64篇 |
1996年 | 86篇 |
1995年 | 69篇 |
1994年 | 75篇 |
1993年 | 94篇 |
1992年 | 105篇 |
1991年 | 100篇 |
1990年 | 78篇 |
1989年 | 94篇 |
1988年 | 86篇 |
1987年 | 61篇 |
1986年 | 61篇 |
1985年 | 101篇 |
1984年 | 109篇 |
1983年 | 60篇 |
1982年 | 64篇 |
1981年 | 54篇 |
1980年 | 60篇 |
1979年 | 68篇 |
1978年 | 65篇 |
1977年 | 77篇 |
1976年 | 51篇 |
1975年 | 45篇 |
1974年 | 46篇 |
1973年 | 51篇 |
排序方式: 共有6216条查询结果,搜索用时 15 毫秒
921.
Makoto Obata Yurie Tanaka Naoko Araki Shiho Hirohara Shigenobu Yano Kazunori Mitsuo Keisuke Asai Masafumi Harada Toyoji Kakuchi Chikara Ohtsuki 《Journal of polymer science. Part A, Polymer chemistry》2005,43(14):2997-3006
Pressure‐sensitive paint (PSP), which consists of luminescent molecules embedded in an oxygen‐permeable polymer, has been developed for use in wind‐tunnel experiments. To improve the PSP technique, a novel luminescent methacrylate monomer, 5‐[4‐(2‐methacryloyloxyethoxycarbonyl)phenyl]‐10,15,20‐triphenylporphinato platinum(II), was synthesized and copolymerized with isobutyl methacrylate and 2,2,2‐trifluoroethyl methacrylate to produce a dye‐pendant copolymer ( 2 ). The introduction of 5,10,15,20‐tetraphenylporphinato platinum(II) (PtTPP) dye into 2 was confirmed by ultraviolet–visible spectroscopy and extended X‐ray absorption fine structure measurements. The extent of PtTPP dye incorporation in 2 was proportional to the molar fraction of the PtTPP‐pendant methacrylate monomer in the feed. The oxygen‐sensing property of 2 was compared with that of a PSP consisting of PtTPP dye embedded in poly(isobutyl‐co‐2,2,2‐trifluoroethyl methacrylate). Although the simple mixture of PtTPP and poly(isobutyl‐co‐2,2,2‐trifluoroethyl methacrylate) showed a marked deviation from a single Stern–Volmer relation, novel copolymer 2 gave a highly linear Stern–Volmer plot. This was unequivocal evidence of dye conjugation on the oxygen‐sensing polymer film. © 2005Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 2997–3006, 2005 相似文献
922.
The surface structure of Ce adsorbed on a Mo(110) surface was studied by reflection high energy electron diffraction. Five kinds of surface structures were found with different deposition coverages in the submonolayer region. These structures have a common feature that Ce atoms possess a periodicity with double spacing at the atomic rows in the Mo[
10] direction. Observed at 1 ML of Ce coverage was a surface structure related to a deformed fcc Ce(111) plane. 相似文献
923.
Shunitz Tanaka Kazuharu Sugawara Mitsuhiko Taga 《Fresenius' Journal of Analytical Chemistry》1990,338(8):898-901
Summary The cathodic stripping voltammetry of copper(II) was investigated with a method, based on the adsorptive accumulation of the Cu(II)-salicylideneamino-2-thiophenol (SATP) complex on a hanging mercury drop electrode. The copper(II)-SATP complex could be accumulated on the electrode at –0.20 V in 0.01 mol/l nitric acid. The reduction peak of the copper complex was observed by scanning the potential in a negative direction in the differential pulse mode. The calibration curve for copper was linear over the range 5×10–9–1×10–7 mol/l. This method was applied to determine copper(II) in GSJ (Geological Survey of Japan) standard rock reference materials. 相似文献
924.
This paper describes the development of the depth profiling method of ultra trace metal impurities in polytetrafluoroethylene (PTFE) wares based on contamination-free sampling followed by acid-vapor extraction and its application to evaluate the washing method for PTFE wares. A contamination-free sampling process was achieved by scraping the surface of PTFE wares with the cleft face of a silicon wafer followed by exposing the PTFE scraped to highly pure acid-vapor. The concentration of metal impurities in extractants was determined by ICP-MS equipped with an electrothermal vaporizer (ETV-ICP-MS). The blank values of Al, Cr, Fe, Ni and Cu by the depth profiling method were 0.006, 0.004, 0.005, 0.002 and 0.003 ng, respectively. By analyzing the depth profile of beakers, the distributions of ultra trace (ng g(-1) level) metal impurities were clarified. An examination of the washing methods by the depth profiling method also clarified that exposing to acid-vapor was more effective than the acid-dipping method for the elimination of metal impurities. 相似文献
925.
Y. Ohtsu O. Shirota T. Ogawa I. Tanaka T. Ohta O. Nakata Y. Fujiyama 《Chromatographia》1987,24(1):351-356
Summary A new type of column packing material designed for preparative liquid chromatography, silicone polymer-coated silica gel modified
with octadecyl group (S/S-C18), was applied to chromatographic purification of a lipophilic biotechnological product. Triglycerides containing γ-linolenic
acid were separated from the curde oil that consisted of triglycerides, diglycerides, free fatty acids, sterols and other
polar substances, using a S/S-C18 packed column (150 mm I.D. × 1000 mm). No column deterioration was observed after more than 1500 times of sample introductions. 相似文献
926.
A waveguide-type optical frequency shifter based on a rotating half-wave plate is proposed. The underlying principle can be used to realize a bit-rate-free and modulation-code-free optical frequency shifter. The waveguide was formed along the ≪1 1 1> direction on a GaAs (1 1 0) substrate by molecular beam epitaxy (MBE) and reactive ion beam etching (RIBE). A 10-MHz optical frequency shift with 16 Vp-p applied voltage and 22.5% shift efficiency is demonstrated. 相似文献
927.
928.
K. Okada T. Nakamura S. Ohtani M. Wada J. Tanaka H. Kawakami I. Katayama D. Schnier H.A. Schuessler O. Becker F. Arbes G. Werth 《Applied physics. B, Lasers and optics》1996,62(1):91-95
A technique is proposed for injection-seeding control of tunable lasers. It is based on a combination of successive external injection and intracavity self-injection of radiation when the active medium is pumped by dual-step pulses. The technique is tested both experimentally (in the case of Nd:YAG-laser-pumped pulsed dye lasers) and numerically, using a model developed by us. Full conversion of the broadband spectrum into the injected line is achieved for an output energy greater by a factor of about 50 than that managed by means of the traditional injection-seeding technique under identical conditions. 相似文献
929.
Nemoto Rei Wang Li Ikoma Toshiyuki Tanaka Junzo Senna Mamoru 《Journal of nanoparticle research》2004,6(2):259-265
Hydroxyapatite (HAp) nanocrystals were prepared at room temperature by a coprecipitation method from Ca(OH)2 and H3PO4, in the presence of chemically disintegrated silk fibroin (SF). Adsorbed amounts of cations on SF and crystallinity of HAp in the composite were increased by the chemical disintegration of SF higher order structure. Preferential alignment of c-axis of HAp crystallites along the longitudinal direction of ca. 150nm SF fibril was observed. These changes due to disintegration of SF were discussed in terms of the chemical interaction between HAp and SF. The resulted composite with preferential alignment of HAp nanocrystals is a good candidate as a starting material for bone substitutes. 相似文献
930.
M. Fujita T. Endo A. Yamazaki T. Sonada T. Miyake E. Tanaka T. Shinozuka T. Suzuki A. Goto Y. Miyashita N. Sato Y. Wakabayashi N. Hokoiwa M. Kibe Y. Gono T. Fukuchi A. Odahara 《Hyperfine Interactions》2004,159(1-4):245-249
The g-factor of the 27− isomer state of 152Dy has been measured using the Time-Integral Perturbed Angular Distribution (TIPAD) method. The high-spin states of 152Dy have been populated by 141Pr(16O,p4n)152Dy reaction at E = 115 MeV from the AVF cyclotron at CYRIC. The paramagnetic correction factor of Dy ions in Pr has been determined to be
4.2(5) by the Time-Differential Perturbed Angular Distribution (TDPAD) measurement of the 21− state of 152Dy. As a result, the g-factor of the 27− isomer state of 152Dy has been obtained to be +0.09(5). This shows the smaller value than the expected one of +0.39 deduced from a fully aligned
configuration of π(h
11/2
2) ⊗ ν(f
7/2
2
h
9/2
i
13/2). 相似文献