全文获取类型
收费全文 | 1290篇 |
免费 | 15篇 |
国内免费 | 14篇 |
专业分类
化学 | 969篇 |
晶体学 | 17篇 |
力学 | 12篇 |
数学 | 93篇 |
物理学 | 228篇 |
出版年
2022年 | 5篇 |
2021年 | 5篇 |
2020年 | 5篇 |
2019年 | 18篇 |
2018年 | 5篇 |
2017年 | 6篇 |
2016年 | 14篇 |
2015年 | 16篇 |
2014年 | 18篇 |
2013年 | 83篇 |
2012年 | 48篇 |
2011年 | 60篇 |
2010年 | 34篇 |
2009年 | 39篇 |
2008年 | 63篇 |
2007年 | 76篇 |
2006年 | 74篇 |
2005年 | 69篇 |
2004年 | 54篇 |
2003年 | 60篇 |
2002年 | 69篇 |
2001年 | 25篇 |
2000年 | 30篇 |
1999年 | 12篇 |
1998年 | 18篇 |
1997年 | 21篇 |
1996年 | 23篇 |
1995年 | 15篇 |
1994年 | 22篇 |
1993年 | 13篇 |
1992年 | 24篇 |
1991年 | 6篇 |
1990年 | 13篇 |
1989年 | 15篇 |
1988年 | 20篇 |
1987年 | 6篇 |
1986年 | 16篇 |
1985年 | 16篇 |
1984年 | 17篇 |
1983年 | 15篇 |
1982年 | 21篇 |
1981年 | 24篇 |
1980年 | 6篇 |
1979年 | 22篇 |
1978年 | 13篇 |
1977年 | 16篇 |
1976年 | 11篇 |
1975年 | 17篇 |
1974年 | 11篇 |
1973年 | 9篇 |
排序方式: 共有1319条查询结果,搜索用时 15 毫秒
71.
Yasuo Kameda Takuya Miyazaki Toshiya Otomo Yuko Amo Takeshi Usuki 《Journal of solution chemistry》2014,43(9-10):1588-1600
Neutron diffraction measurements were carried out at 25 °C for aqueous LiNO3 heavy water solutions, (*LiNO3) x (D2O)1?x where x = 0.1, 0.05 and 0.01, in which the 6Li/7Li isotopic ratios were varied. Structural information on intermolecular nearest neighbor Li+···D2O interactions in the extensive concentration range was derived from the first-order difference function, ?Li(Q), obtained from the difference in scattering cross sections between 6Li- and 7Li-enriched sample solutions. The nearest neighbor Li+···O distance and coordination number for sample solution with x = 0.1 were determined to be r LiO = 1.969 (8) Å and n LiO = 4.12 (6), respectively, corresponding to the four-coordinated Li+ ion in the solution. On the other hand, those obtained for the solution with x = 0.01 are r LiO = 2.00 (2) Å and n LiO = 6.0 (2), respectively, indicating that hexaaqua Li+ is dominant in the dilute solution. These results clearly indicate that a concentration dependence of the hydration number of Li+ occurs in the aqueous solutions. 相似文献
72.
Dai Kato Atsumu Oda Mutsuo Tanaka Seiichiro Iijima Tomoyuki Kamata Masami Todokoro Yasuo Yoshimi Osamu Niwa 《Electroanalysis》2014,26(3):618-624
We developed an electrochemical system for detecting lipopolysaccharide (LPS) that uses an ultraflat nanocarbon film electrode modified with poly‐ε‐lysine with a high affinity to LPS. LPS was captured on the modified electrode, and then ferrocene labeled polymyxin B (FcPMB) was captured on the LPS adsorbed electrode via the LPS‐PMB affinity interaction. The adsorbed FcPMB provided an amplified response with Fe2+ ions, and the current response was dependent on the amount of captured LPS (LOD=2.0 ng/mL). This was due to the efficient accumulation of the obtained current for LPS and the very low noise made possible by the ultraflat surface. 相似文献
73.
74.
Masaru Yoshida Masaharu Asano Hideki Omichi Masaharu Miyajima Yasuo Takahashi Hidetoshi Yamanaka Noriyuki Yonezawa Ryoichi Katakai 《Macromolecular theory and simulations》1993,2(3):377-384
The loosely cross-linked poly(acryloyl-L -proline methyl ester) gel, which is known as one of the typical thermo-responsive gels, shows a volume transition around approximately 14°C in pure water. This volume transition is shifted to higher temperature by treatment in aqueous sodium dodecyl sulfate (SDS). The analysis of the swelling-temperature curve (frequency distribution) was performed according to a moment analysis, in which the area under the swelling-temperature curve (AUC), mean swelling transition temperature (MSTT) and variance of swelling transition temperature (VSTT) were calculated. It is shown that the apparent volume transition temperature can be estimated from MSTT and that VSTT can be used to characterize the shape of the corresponding curves. 相似文献
75.
Yasuo Horikawa Takeshi Takeda Toshiki Takizawa Taro Akazawa Ryota Fujio Tatsuo Fujimaki 《Journal of polymer science. Part A, Polymer chemistry》1996,34(7):1183-1188
The anionic polymerization of 1,3-butadiene using a novel metalloidal anion initiator, triallylstannyllithium (TALi)-allyllithium (ALi), was studied. The TALi-ALi initiated anionic polymerization of 1,3-butadiene gave the star polymer along with the linear polybutadiene (PBD). The star polymer consisted of three PBD branches and a central tin atom. What is striking is a fact that the number-average molecular weights (Mn) and molecular weight distribution of three PBD branches and linear PBD were almost identical. A reversible chain transfer polymerization mechanism, which includes the equilibrium between tri(macroallyl)-stannyllithium and macroallylic anion, is proposed. © 1996 John Wiley & Sons, Inc. 相似文献
76.
Pedro L. R. Guedes Carolina P. F. Carvalho Adriana A. F. Carbonel Manuel J. Simes Marcelo Y. Icimoto Jair A. K. Aguiar Maria Kouyoumdjian Marcos L. Gazarini Marcia R. Nagaoka 《Molecules (Basel, Switzerland)》2022,27(3)
During liver fibrogenesis, there is an imbalance between regeneration and wound healing. The current treatment is the withdrawal of the causing agent; thus, investigation of new and effective treatments is important. Studies have highlighted the action of chondroitin sulfate (CS) in different cells; thus, our aim was to analyze its effect on an experimental model of bile duct ligation (BDL). Adult Wistar rats were subjected to BDL and treated with CS for 7, 14, 21, or 28 days intraperitoneally. We performed histomorphometric analyses on Picrosirius-stained liver sections. Cell death was analyzed according to caspase-3 and cathepsin B activity and using a TUNEL assay. Regeneration was evaluated using PCNA immunohistochemistry. BDL led to increased collagen content with corresponding decreased liver parenchyma. CS treatment reduced total collagen and increased parenchyma content after 21 and 28 days. The treatment also promoted changes in the hepatic collagen type III/I ratio. Furthermore, it was observed that CS treatment reduced caspase-3 activity and the percentage of TUNEL-positive cells after 14 days and cathepsin B activity only after 28 days. The regeneration increased after 14, 21, and 28 days of CS treatment. In conclusion, our study showed a promising hepatoprotective action of CS in fibrogenesis induced by BDL. 相似文献
77.
Kawahara M Kabir MK Yamada K Adachi K Kumagai H Narumi Y Kindo K Kitagawa S Kawata S 《Inorganic chemistry》2004,43(1):92-100
Two new copper(II) compounds of chloranilate and 2,2':6',2' '-terpyridine have been synthesized, and the structures have been solved by the single-crystal X-ray diffraction method. The crystal structure of [[Cu(2)(CA)(terpy)(2)][Cu(CA)(2)]](n)(1), where H(2)CA = chloranilic acid and terpy = 2,2':6',2' '-terpyridine, consists of two modules, the dimer unit [Cu(2)(CA)(terpy)(2)](2+) and the anionic mononuclear unit [Cu(CA)(2)](2)(-), forming an alternated chain. The chain is stabilized by semicoordinating and additional but efficient secondary bonding interactions. The crystal structure of [[Cu(2)(CA)(terpy)(2)(dmso)(2)][Cu(CA)(2)(dmso)(2)](EtOH)](n)(2), where dmso = dimethyl sulfoxide, consists of solvent molecules and two discrete modules, the dimer unit [Cu(2)(CA)(terpy)(2)(dmso)(2)](2+) and the anionic mononuclear unit [Cu(CA)(2)(dmso)(2)](2)(-). The dimer units form a layer by secondary bonding interactions, and the monomer units and ethanol molecules are introduced between the layers. The magnetic properties of 1 and 2 have been investigated in the temperature range 2.0-300 K. A weak ferromagnetic interaction was observed in 1, J(a) = 2.36 cm(-)(1) and zJ(b) = -0.68 cm(-)(1) while no exchange coupling was observed in 2. 相似文献
78.
Tomohiro Takano Chutiparn Lertvachirapaiboon Yasuo Ohdaira Akira Baba Keizo Kato 《Molecular Crystals and Liquid Crystals》2019,685(1):93-99
AbstractGas sensing by using the transmission surface plasmon resonance (T-SPR) technique was demonstrated. Polyacrylic acid (PAA)/5-nm-thick gold/40-nm-thick silver/polycarbonate grating substrate structure (Sensor A) responded to ammonia; however, it exhibited a strong humidity dependence. Polyvinyl alcohol (PVA)/5-nm-thick gold/40-nm-thick silver/polycarbonate grating substrate structure (Sensor B) as the sensing material was also prepared and it mainly responded to humidity. The T-SPR properties of Sensors A and B were observed simultaneously by a stacking arrangement that enabled us to obtain the responses by using a single spectrophotometer. The ammonia concentration under various humidity conditions could be accurately obtained by simultaneous measurement of Sensors A and B. 相似文献
79.
Yasuda K Torii T Yasui K Iida Y Tuziuti T Nakamura M Asakura Y 《Ultrasonics sonochemistry》2007,14(6):699-704
The ultrasonic reactor with dual frequency was used and the effect of frequency on the fluorescence intensity of terephthalate ion was experimentally investigated in the frequency range from 176 to 635 kHz. The sonochemical reaction fields were visualized by using sonochemical luminescence of luminol solution. Compared with the fluorescence intensity of terephthalate ion for single frequency, the fluorescence intensity for dual frequency increased. The fluorescence intensity ratio of dual frequency to single frequency had maximum value when the frequency of transducer attached at the bottom wall was comparable in magnitude to that at the side wall. In the case of dual frequency, the sonochemical reaction fields became more extensive in the reactor and more intensive around the center of the reactor. 相似文献
80.
In our previous paper Ohkuwa et al. (2016) corrigendum was found in Eqs. (3.4) and (3.6). However, conclusions of our previous paper are not changed. 相似文献