全文获取类型
收费全文 | 2537篇 |
免费 | 68篇 |
国内免费 | 9篇 |
专业分类
化学 | 1879篇 |
晶体学 | 20篇 |
力学 | 27篇 |
综合类 | 1篇 |
数学 | 121篇 |
物理学 | 566篇 |
出版年
2021年 | 23篇 |
2020年 | 31篇 |
2019年 | 31篇 |
2018年 | 20篇 |
2017年 | 18篇 |
2016年 | 40篇 |
2015年 | 33篇 |
2014年 | 38篇 |
2013年 | 89篇 |
2012年 | 120篇 |
2011年 | 147篇 |
2010年 | 77篇 |
2009年 | 101篇 |
2008年 | 133篇 |
2007年 | 131篇 |
2006年 | 127篇 |
2005年 | 130篇 |
2004年 | 111篇 |
2003年 | 116篇 |
2002年 | 100篇 |
2001年 | 63篇 |
2000年 | 41篇 |
1999年 | 46篇 |
1998年 | 33篇 |
1997年 | 42篇 |
1996年 | 45篇 |
1995年 | 31篇 |
1994年 | 24篇 |
1993年 | 39篇 |
1992年 | 38篇 |
1991年 | 32篇 |
1990年 | 37篇 |
1989年 | 27篇 |
1988年 | 29篇 |
1987年 | 23篇 |
1986年 | 19篇 |
1985年 | 37篇 |
1984年 | 41篇 |
1983年 | 22篇 |
1982年 | 31篇 |
1981年 | 34篇 |
1980年 | 36篇 |
1979年 | 27篇 |
1978年 | 26篇 |
1977年 | 26篇 |
1976年 | 19篇 |
1975年 | 18篇 |
1974年 | 19篇 |
1973年 | 12篇 |
1969年 | 11篇 |
排序方式: 共有2614条查询结果,搜索用时 15 毫秒
61.
Yukihiro Shintani Keiji Hirako Masanori Motokawa Yoshihiko Takano Masahiro Furuno Hiroyoshi Minakuchi Mitsuyoshi Ueda 《Analytical sciences》2004,20(12):1721-1723
An interconnecting technique, the "PDMS connection method", for quartz microchips in a high-pressure system is presented. The connection between quartz microchips is an essential technology for modular microfluidic devices, such as microchip-HPLC. PDMS was applied to the seal material, being spread on the seal side of the chips, and set into the metal housing. The characteristics of the PDMS connection method concerning pressure resistance and the extension of the peak were examined. The experimental results showed a good seal at 5 MPa, which seem to be sufficient for realizing microchip-HPLC utilizing a monolithic silica capillary column as a separation medium. The influence of the extra column effect on chromatographic separation was almost the same as in the case using a commercial union fitting. In addition, the PDMS connection enabled the detachability of chip-based modules with user-friendliness. Our experimental findings suggest that the novel PDMS connection method can possibly be applied as a generic technology in high-pressure microTAS. 相似文献
62.
Shin-ichi OhsugiKiyoharu Nishide Keiji OonoKazunori Okuyama Masato FudesakaSumiaki Kodama Manabu Node 《Tetrahedron》2003,59(42):8393-8398
Development of the odorless dodecyl methyl sulfide (Dod-S-Me, 1) as an alternative for dimethyl sulfide (DMS) and new odorless methods for the Corey-Kim and Swern oxidations are described. These reactions have been developed with a view toward green chemistry, utilizing Dod-S-Me (1) and common solvents instead of dichloromethane. 相似文献
63.
Neil C. Concibido Tetsuji Okuda Wataru Nishijima Mitsumasa Okada 《Reaction Kinetics and Catalysis Letters》2006,89(2):369-376
Summary The hydrodechlorination of tetrachloroethylene in methanol (MeOH) over palladium catalysts on activated carbon (Pd/C) at 20°C
and atmospheric pressure was rendered safer by using ethanol (EtOH), isopropanol (IPA) or water-alcohol mixtures as solvents.
Adding water to MeOH was better than using EtOH or IPA since it resulted in a faster reaction and better stability of Pd/C,
which could also be completely reactivated. 相似文献
64.
65.
66.
A direct preparative route to benzoyltrimethylsilane has been found by the reaction of benzoyl chloride with hexamethyldisilane in the presence of a specified palladium(II) complex as catalyst. 相似文献
67.
Bendazzoli Gianni L. Raimondi Mario Garetz Bruce A. George Thomas F. Morokuma Keiji 《Theoretical chemistry accounts》1977,44(4):341-350
Semiclassical calculations are carried out by two methods for the problem of collision-induced predissociation of electronically excited I2. The first method is that of surface-hopping with the Landau-Zener model. The second method is similar to surface-hopping, except that analytic continuation of the adiabatic potential energy surfaces replaces the Landau-Zener model. Results of the calculations by the two methods compare favorably with each other and with experiment. The possible advantages of the second method are discussed.Camille and Henry Dreyfus Teacher-Scholar, Alfred P. Sloan Research Fellow. 相似文献
68.
Takuma Shinya Nakashima Noriyuki Tantirungkij Manee Kinoshita Shinichi Okada Hirosuke Sew TatsÜji Yoshida Toshiomi 《Applied biochemistry and biotechnology》1991,28(1):327-340
Applied Biochemistry and Biotechnology - A NADPH/NADH-dependent xylose reductase gene was isolated from the xylose-assimilating yeast,Pichia stipitis. DNA sequence analysis showed that the gene... 相似文献
69.
In the course of a population study of alpha 1-antitrypsin polymorphism by separator isoelectric focusing, a variant phenotype having a somewhat narrower spacing than PI M1M3 was observed in a Japanese blood donor. Family studies by hybrid isoelectric focusing in a carrier ampholyte-supplemented immobilized pH gradient from 4.35-4.65 revealed that the products of the responsible gene, PI*Mtoyoura, were extremely close but slightly cathodal to those of PI*M1. The difference in isoelectric point between them corresponded to the resolving limit of isoelectric focusing. For this reason, although the propositus' father was deduced to have the genotype PI*M1/PI*Mtoyoura, the products of these two genes failed to form a double band pattern. Thus, the gene frequency for PI*Mtoyoura was unknown. These findings, however, indicate that a further microheterogeneity in the PI M subtype exists at least in the Japanese. 相似文献
70.