全文获取类型
收费全文 | 3688篇 |
免费 | 132篇 |
国内免费 | 20篇 |
专业分类
化学 | 2798篇 |
晶体学 | 57篇 |
力学 | 34篇 |
数学 | 154篇 |
物理学 | 797篇 |
出版年
2022年 | 24篇 |
2021年 | 23篇 |
2020年 | 35篇 |
2019年 | 42篇 |
2018年 | 42篇 |
2017年 | 30篇 |
2016年 | 60篇 |
2015年 | 64篇 |
2014年 | 84篇 |
2013年 | 175篇 |
2012年 | 196篇 |
2011年 | 237篇 |
2010年 | 140篇 |
2009年 | 140篇 |
2008年 | 222篇 |
2007年 | 228篇 |
2006年 | 238篇 |
2005年 | 233篇 |
2004年 | 179篇 |
2003年 | 186篇 |
2002年 | 173篇 |
2001年 | 64篇 |
2000年 | 51篇 |
1999年 | 55篇 |
1998年 | 30篇 |
1997年 | 39篇 |
1996年 | 53篇 |
1995年 | 25篇 |
1994年 | 38篇 |
1993年 | 32篇 |
1992年 | 46篇 |
1991年 | 34篇 |
1990年 | 27篇 |
1989年 | 26篇 |
1988年 | 20篇 |
1987年 | 21篇 |
1986年 | 33篇 |
1985年 | 65篇 |
1984年 | 61篇 |
1983年 | 20篇 |
1982年 | 48篇 |
1981年 | 50篇 |
1980年 | 45篇 |
1979年 | 34篇 |
1978年 | 30篇 |
1977年 | 26篇 |
1976年 | 24篇 |
1975年 | 14篇 |
1974年 | 15篇 |
1973年 | 17篇 |
排序方式: 共有3840条查询结果,搜索用时 15 毫秒
91.
New low-molecular-weight gelators based on l-valine and l-isoleucine gelators, which have a positively charged terminal group, can gel not only pure water and aqueous solutions containing inorganic acids and salts but also some organic solvents and oils. 相似文献
92.
93.
N-Acyl-α-amino acids are synthesized by the amidocarbonylation of allylic alcohols catalyzed by homogeneous binary systems which consist of cobalt carbonyl and rhodium (or iron or palladium) complexes. 相似文献
94.
Takashi Hirota Kenji Sasaki Yohsuke Tashima Taiji Nakayama 《Journal of heterocyclic chemistry》1991,28(2):263-267
Syntheses of 2,3-dihydrobenzofuro[2,3-e]imidazo[1,2-c]pyrimidine and its 5-substituted derivatives, corresponding to B-nor-6-oxa-11,13,15-triazasteroids, are described. These products and their precursors were screened to evaluate the antidepressive activity. 相似文献
95.
Qi ZM Matsuda N Santos J Yoshida T Takatsu A Kato K 《Journal of colloid and interface science》2004,271(1):249-253
Broadband, time-resolved optical waveguide (OWG) spectroscopy has been used for in situ, real-time investigation into the self-assembly of metal nanoparticle monolayers. The OWG spectroscopy makes it possible to use the transverse electric (TE) and transverse magnetic (TM) modes to measure surface plasmon absorption of immobilized metal nanoparticles in two directions, parallel and normal to the waveguide surface. Therefore, this technique can provide direction-dependent information on the metal nanoparticles at the interface. In this paper, a 50-microm-thick glass plate was used as a slab waveguide and the kinetics of Au nanoparticle adsorption on a hemoglobin-functionalized glass substrate was examined in the early stage of self-assembly. The findings show that with the TE mode the surface plasmon resonance (SPR) behavior for immobilized Au nanoparticles is different from that with the TM mode. 相似文献
96.
(+-)-3,3,7-Trimethyl-2,9-dioxatricyclo[4.2.1.04, 7]noname and (+-)-3,3,7-trimethyl-2,9-dioxatricyclo[3.3.1.04, 7] nonane were synthesized. The latter was shown to be (+-)-lineatin, an ambrosia beetle pheromone. 相似文献
97.
98.
Funyu S Isobe T Takagi S Tryk DA Inoue H 《Journal of the American Chemical Society》2003,125(19):5734-5740
Visible light irradiation of a reaction mixture of carbonyl-coordinated tetra(2,4,6-trimethyl)phenylporphyrinatoruthenium(II) (Ru(II)TMP(CO)) as a photosensitizer, hexachloroplatinate(IV) as an electron acceptor, and an alkene in alkaline aqueous acetonitrile induces selective epoxidation of the alkene with high quantum yield (Phi = 0.6, selectivity = 94.4% for cyclohexene and Phi = 0.4, selectivity = 99.7% for norbornene) under degassed conditions. The oxygen atom of the epoxide was confirmed to come from a water molecule by an experiment with H(2)(18)O. cis-Stilbene was converted into its epoxide, cis-stilbeneoxide, without forming trans-stilbeneoxide. trans-Stilbene, however, did not exhibit any reactivity. Under neutral conditions, an efficient buildup of the cation radical of Ru(II)TMP(CO) was observed at the early stage of the photoreaction, while an addition of hydroxide ion caused a rapid reaction with the cation radical to promote the reaction with reversion to the starting Ru(II)TMP(CO). A possible involvement of a higher oxidized state of Ru such as Ru(IV), Ru(V), Ru(VI) through a dismutation of the Ru(III) species was excluded by an experiment with Ru(VI)TMP(O)(2). Decarbonylation of the Ru complex was also proven to be invalid. A reaction mechanism involving an electron transfer from the excited triplet state of Ru(II)TMP(CO) to hexachloroplatinate(IV) and subsequent formation of OH(-)-coordinated Ru(III) species, leading to an oxo-ruthenium complex as the key intermediate of the photochemical epoxidation, was postulated. 相似文献
99.
Sugimoto K Nishida M Otsuka M Makino K Ohkubo K Mori Y Morii T 《Chemistry & biology》2004,11(4):475-485
Real-time observation of messenger molecules in individual intact cells is essential for physiological studies of signaling mechanisms. We have developed a novel inositol 1,4,5-trisphosphate (IP(3)) sensor based on the pleckstrin homology (PH) domain from phospholipase C (PLC) delta. The environmentally sensitive fluorophore 6-bromoacetyl-2-dimethyl-aminonaphtalene was conjugated to the genetically introduced cysteine at the mouth of the IP(3) binding pocket for enhanced IP(3) selectivity and for rapid and direct visualization of intracellular IP(3) > or = 0.5 microM as fluorescence emission decreased. The probe, tagged with arginine-rich sequences for efficient translocation into various cell types, revealed a major contribution of Ca2+ influx to PLC-mediated IP(3) production that boosts Ca2+ release from endoplasmic reticulum. Thus, our IP(3) probe was extremely effective to quantitatively assess real-time physiological IP(3) production via those pathways formed only in the intact cellular configuration. 相似文献
100.
Zhang Guozhen Tetsuya Shichi Tong Zhiwei Katsuhiko Takagi 《Research on Chemical Intermediates》2007,33(1-2):155-160
A new organic/inorganic hybrid material was prepared by the polymerization of bis(hydroxyethyl) terephthalate (BHET) with a layered niobate compound, H4Nb6O17, modified by 11-aminoundecanoic acid (AUA). The hybrid polymer films of BHET with H4Nb6O17/AUA exhibited favorable characteristics, particularly of being optically clear, indicating the exfoliation and homogeneous dispersion of H4Nb6O17 into the PET/niobate hybrid. 相似文献