全文获取类型
收费全文 | 1328篇 |
免费 | 35篇 |
国内免费 | 4篇 |
专业分类
化学 | 986篇 |
晶体学 | 11篇 |
力学 | 11篇 |
数学 | 110篇 |
物理学 | 249篇 |
出版年
2023年 | 5篇 |
2022年 | 5篇 |
2021年 | 11篇 |
2020年 | 15篇 |
2019年 | 17篇 |
2018年 | 13篇 |
2017年 | 12篇 |
2016年 | 29篇 |
2015年 | 30篇 |
2014年 | 27篇 |
2013年 | 62篇 |
2012年 | 55篇 |
2011年 | 80篇 |
2010年 | 45篇 |
2009年 | 50篇 |
2008年 | 79篇 |
2007年 | 82篇 |
2006年 | 80篇 |
2005年 | 72篇 |
2004年 | 80篇 |
2003年 | 48篇 |
2002年 | 49篇 |
2001年 | 37篇 |
2000年 | 23篇 |
1999年 | 10篇 |
1998年 | 19篇 |
1997年 | 10篇 |
1996年 | 17篇 |
1995年 | 10篇 |
1994年 | 12篇 |
1993年 | 11篇 |
1992年 | 18篇 |
1991年 | 10篇 |
1990年 | 19篇 |
1989年 | 19篇 |
1988年 | 13篇 |
1987年 | 13篇 |
1985年 | 15篇 |
1984年 | 23篇 |
1983年 | 12篇 |
1982年 | 15篇 |
1981年 | 17篇 |
1980年 | 8篇 |
1979年 | 11篇 |
1978年 | 13篇 |
1977年 | 10篇 |
1976年 | 7篇 |
1975年 | 10篇 |
1974年 | 8篇 |
1973年 | 6篇 |
排序方式: 共有1367条查询结果,搜索用时 15 毫秒
31.
Asymmetric catalytic hydrogenations of three kinds of chiral pyruvamides were carried out using palladium on charcoal as a catalyst to give lactamides with diastereomeric ratios ranging from 76:24 to 98:2. 相似文献
32.
W. Clark Still Lawrence J. Macpherson Toshiro Harada James F. Callahan Arnold L. Rheingold 《Tetrahedron》1984,40(12):2275-2281
The conformations of macrocyclic intermediates provide a useful medium through which distant chiral centers may control chemical reactions. In this paper, we show that macrocycles made by cyclization of simple acyclic starting materials with an auxiliary spacer may be used to prepare stereochemically complex acyclic products. 相似文献
33.
Concanavalin A (Con A) was biotinylated to various degrees using N-biotinyl-omega-aminocaproic-acid-N-hydroxy succinimide ester as the biotinylation reagent, and then analyzed by isoelectric focusing using PhastGel IEF 3-9. The isoelectric points of biotinylated ConAs were found to decrease with increasing concentration of the biotinylation reagent. Analysis by isoelectric focusing followed by dot blotting clearly indicated that the biotinylated ConA with an isoelectric point lower than that of the original ConA by 2.2 +/- 0.6 had the strongest binding activity for ovalbumin. 相似文献
34.
Tamás Veszprémi Yoshiya Harada Koichi Ohno Hideki Mutoh 《Journal of organometallic chemistry》1983,252(2):121-125
Penning ionization electron spectroscopy and CNDO/S calculations have been successfully applied to the analyses of the UV photoelectron spectra of 2- and 2,5-bistrimethylsilylthiophene and 2-t-butylthiophene. The relative intensities of the π type bands are greatly enhanced in the Penning spectra compared with those of the UV photoelectron spectra. 相似文献
35.
Tetsuro Kato Ryosuke Nemoto Hisashi Mori Ryoetsu Abe Katsuo Unno Akio Goto Hideyuki Murota Masaoki Harada Motofumi Homma 《Applied biochemistry and biotechnology》1984,10(1-3):199-211
To achieve targeted distribution of anticancer drugs with sustained activity, ferromagnetic ethylcellulose microcapsules containing
an anticancer drug, mitomycin C (FM-MMC-mc), were prepared by a method based on phase separation principles. Two prototypes
of FM-MMC-mc were made: one with the drug as the core and zinc ferrite on its capsular surface (outer type); the other with
both the drug and zinc ferrite as the core (inner type). Both preparations provided a sustained-release property and a sensitive
response to conventional magnetic force, although certain differences in the release rate of drug, magnetic responsiveness,
and particle size were found between the two dosage forms. Animal studies showed that the magnetic microcapsules could be
magnetically controlled in the artery and urinary bladder. VX2 tumors in the rabbit hind limb and urinary bladder were successfully
treated with magnetic control of FM-MMC-mc. Pharmacokinetic study revealed that the targeting of the microcapsules markedly
enhanced the drug absorption into the surrounding tissues for a prolonged period of time. The results indicate the feasibility
and effectiveness of the magnetic microcapsules as a targeted drug delivery system. 相似文献
36.
Harada H Kazami J Watanuki S Tsuzuki R Sudoh K Fujimori A Tanaka A Tsukamoto S Yanagisawa I 《Chemical & pharmaceutical bulletin》2001,49(5):606-612
In the present article we wish to report the discovery of a novel class of ET(A)-selective endothelin (ET) receptor antagonists through the modification of the ET(A)/ET(B) non-selective antagonist, Ro47-0203 (Bosentan, 1). Replacement of the benzenesulfonamide group of 1 with a 2-phenylethenesulfonamide group gave compound 5a and resulted in improvement in ET(A)-selectivity. Optimization of the alkoxy side chain attached to the core pyrimidine ring yielded the 2-fluoroethoxy derivative (5n) with further improvement of ET(A)-selectivity. [IC50=2.1 nM for ET(A) receptor, ET(B)/ET(A) ratio=1200]. After oral administration, compound 5n inhibited the big ET-1 induced pressor response in pithed rats with a DR2 value of 2.6 mg/kg and also exhibited a potent antagonistic activity in conscious rats. 相似文献
37.
The ν2 (CD3 symmetrical deformation) and ν5 (CD3 degenerate deformation) fundamental bands of CD3Br were studied by 9.4- and 10.4-μm CO2 laser Stark spectroscopy. Stark resonances originating from 28 and 53 rovibrational transitions of the ν2 and ν5 bands, respectively, were assigned for each of the isotopic species, CD379Br and CD381Br. These two bands were simultaneously analyzed with explicit inclusion of the ν2-ν5 Coriolis interaction, yielding precise molecular constants in the ν2 and ν5 excited states as well as the Coriolis coupling constant. The molecular constants obtained are consistent between the two isotopic species and are in good agreement with the results of high-resolution infrared studies. The band origins and dipole moments are
CD379Br | CD381Br | |||||
991.396 82 (18) | 991.388 46 (17) | cm?1 | ||||
1055.469 00 (12) | 1055.466 32 (12) | cm?1 | ||||
1.830 42 (52) | 1.829 84 (47) | D | ||||
1.829 93 (48) | 1.829 57 (46) | D | ||||
1.832 23 (60) | 1.831 19 (56) | D |