全文获取类型
收费全文 | 1799篇 |
免费 | 53篇 |
国内免费 | 4篇 |
专业分类
化学 | 1303篇 |
晶体学 | 23篇 |
力学 | 25篇 |
数学 | 74篇 |
物理学 | 431篇 |
出版年
2023年 | 8篇 |
2022年 | 6篇 |
2021年 | 15篇 |
2020年 | 17篇 |
2019年 | 28篇 |
2018年 | 11篇 |
2017年 | 5篇 |
2016年 | 31篇 |
2015年 | 25篇 |
2014年 | 36篇 |
2013年 | 80篇 |
2012年 | 115篇 |
2011年 | 91篇 |
2010年 | 56篇 |
2009年 | 45篇 |
2008年 | 116篇 |
2007年 | 112篇 |
2006年 | 118篇 |
2005年 | 116篇 |
2004年 | 99篇 |
2003年 | 93篇 |
2002年 | 102篇 |
2001年 | 38篇 |
2000年 | 32篇 |
1999年 | 19篇 |
1998年 | 27篇 |
1997年 | 16篇 |
1996年 | 19篇 |
1995年 | 20篇 |
1994年 | 14篇 |
1993年 | 12篇 |
1992年 | 15篇 |
1991年 | 18篇 |
1990年 | 20篇 |
1989年 | 16篇 |
1988年 | 19篇 |
1987年 | 19篇 |
1986年 | 23篇 |
1985年 | 14篇 |
1984年 | 24篇 |
1983年 | 17篇 |
1982年 | 12篇 |
1981年 | 23篇 |
1980年 | 19篇 |
1979年 | 29篇 |
1978年 | 12篇 |
1977年 | 12篇 |
1976年 | 7篇 |
1975年 | 12篇 |
1973年 | 8篇 |
排序方式: 共有1856条查询结果,搜索用时 15 毫秒
991.
Adachi K Chayama K Watarai H 《Langmuir : the ACS journal of surfaces and colloids》2006,22(4):1630-1639
A chiral thioether-substituted phthalocyanine ((2,3,9,10,16,17,23,24-octakis-1-phenylethylthiophthalocyaninato)magnesium(II) [MgPc(SEtPh)8]) has been synthesized, which can be bound by soft-metal ions such as palladium(II) ion. Aggregates formed from MgPc(SEtPh)8 and Pd(II) in toluene and at the toluene/water interface were characterized by means of UV-vis absorption and circular dichroism (CD) spectrometries using centrifugal liquid-membrane (CLM) cell. Matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF/MS) and scanning electron microscope (SEM) were used as complementary techniques. The toluene solution of MgPc(SEtPh)8 had no optical chirality. However, the addition of PdCl2 into the toluene solution of MgPc(SEtPh)8 induced optical chirality, which indicated the formation of a twisted H-type dimer (face-to-face fashion) of MgPc(SEtPh)8 bound by four PdCl2 in the bulk toluene solution. On the other hand, in the toluene/water interface, helical J-aggregate (head-to-tail fashion) of MgPc(SEtPh)8 bound by PdCl2 was formed, in which one J-aggregate unit contained five 1:2 complexes of MgPc(SEtPh)8-Pd(II) on average. On the basis of the experimental results and the exciton theory for optical chirality, a possible mechanism for the chiral aggregation of MgPc(SEtPh)8-Pd(II) complexes at the interface was proposed. In the present study, we demonstrated a novel strategy for the design of helical phthalocyanine aggregates using the liquid/liquid interface as a template. 相似文献
992.
Kira A Umeyama T Matano Y Yoshida K Isoda S Isosomppi M Tkachenko NV Lemmetyinen H Imahori H 《Langmuir : the ACS journal of surfaces and colloids》2006,22(12):5497-5503
Clusters of phthalocyanine and phthalocyanine-perylene diimide have been prepared and electrophoretically deposited on nanostructured SnO2 electrodes. The structure and photoelectrochemical properties of the clusters have been investigated by using UV-visible absorption, dynamic light scattering (DLS), atomic force microscopy (AFM), transmission electron microscopy (TEM), and photoelectrochemical and photodynamical measurements. Enhancement of the photocurrent generation efficiency in the composite system has been achieved relative to that in the phthalocyanine reference system without the perylene diimide. Such information will be valuable for the design of molecular photoelectrochemical devices that exhibit efficient photocurrent generation. 相似文献
993.
Teletchéa S Komeda S Teuben JM Elizondo-Riojas MA Reedijk J Kozelka J 《Chemistry (Weinheim an der Bergstrasse, Germany)》2006,12(14):3741-3753
The cytotoxic, pyrazolato-bridged dinuclear platinum(II) complex [(cis-{Pt(NH3)2})2(mu-OH)(mu-pz)]2+ (pz=pyrazolate) has been found to cross-link two adjacent guanines of a double-stranded DNA decamer without destabilizing the duplex and without changing the directionality of the helix axis. A 1H NMR study of the oligonucleotide d(CTCTG*G*TCTC)-d(GAGACCAGAG), cross-linked at the two G* guanines by [(cis-{Pt(NH3)2})2(mu-pz)]3+, and molecular dynamics simulations of the explicitly solvated duplex were performed to characterize the structural details of the adduct. The dinuclear platinum cross-link unwinds the helix by approximately 15 degrees , that is, to a similar extent as the widely used antitumor drug cisplatin, but, in contrast to the latter, induces no significant bend in the helix axis. The Watson-Crick base-pairing remains intact, and the melting temperature of the duplex is unaffected by the cross-link. The helical twist is considerably reduced between the two platinated bases, as becomes manifest in an unusually short sequential H1'-H1' distance. This unwinding also affects the sugar ring of the guanosine in the 3'-position to the cross-link, which presents an N<-->S equilibrium. This is the first cytotoxic platinum complex that has been successfully designed by envisioning the structural consequences of its binding to DNA. 相似文献
994.
The pulse shape and phase of isolated attosecond extreme ultraviolet (XUV) pulses with a duration of 860 asec have been determined simultaneously by using frequency-resolved optical gating based on two-photon above-threshold ionization with 28-eV photons in He. From the detailed characterization, we succeeded in shaping isolated XUV pulses on an attosecond time scale by precise dispersion control with Ar gas density or by changing the driving pulse width. These results offer a novel way to excite and observe an electron motion in atoms and molecules. 相似文献
995.
Ikado K Abe K Abe K Adachi I Aihara H Akai K Akemoto M Anipko D Arinstein K Aulchenko V Aushev T Aziz T Bakich AM Balagura V Barbero M Bay A Bedny I Belous K Bitenc U Bizjak I Bondar A Bozek A Bracko M Browder TE Chang P Chen A Chen WT Choi Y Cole S Dalseno J Danilov M Dash M Eidelman S Epifanov D Flanagan J Fratina S Furukawa K Gabyshev N Gershon T Go A Gokhroo G Golob B Gorisek A Ha H Haba J Hara K Hara T Hastings NC Hayasaka K Hayashii H Hazumi M Hinz L Hokuue T Hoshi Y Hou S Hou WS Iida N 《Physical review letters》2006,97(25):251802
We present the first evidence of the decay B- --> tau- nu(tau), using 414 fb(-1) of data collected at the Upsilon(4S) resonance with the Belle detector at the KEKB asymmetric-energy e+ e- collider. Events are tagged by fully reconstructing one of the B mesons in hadronic modes. We detect the signal with a significance of 3.5 standard deviations including systematics and measure the branching fraction to be B(B- --> tau- nu(tau)) = (1.79(-0.49) +0.56(stat)(-0.51) +0.46(syst)) x 10(-4). This implies that fB = 0.229(-0.031) +0.036(stat)(-0.037) +0.034(syst) GeV and is the first direct measurement of this quantity. 相似文献
996.
Schümann J Wang CH Abe K Adachi I Aihara H Anipko D Arinstein K Asano Y Aushev T Bakich AM Balagura V Barberio E Barbero M Bay A Bedny I Bitenc U Bizjak I Blyth S Bondar A Bozek A Bracko M Browder TE Chang MC Chang P Chao Y Chen A Chen WT Cheon BG Choi Y Choi YK Chuvikov A Cole S Dalseno J Danilov M Dash M Dragic J Drutskoy A Eidelman S Epifanov D Fratina S Gabyshev N Gershon T Go A Gokhroo G Golob B Gorisek A Ha HC Haba J Hara T Hastings NC Hayasaka K Hayashii H Hazumi M Hinz L Hokuue T 《Physical review letters》2006,97(6):061802
We report evidence for the exclusive two-body charmless hadronic B meson decay B-->eta'pi, and improved measurements of B-->eta'K. The results are obtained from a data sample of 386x10(6) BB pairs collected at the Upsilon(4S) resonance, with the Belle detector at the KEKB asymmetric-energy e+e- collider. We measure B(B+-->eta'pi+)=[1.76(-0.62)(+0.67)(stat)(-0.14)(+0.15)(syst)]x10(-6) and B(B0-->eta'pi0)=[2.79(-0.96)(+1.02)(stat)(-0.34)(+0.25)(syst)]x10(-6). We also find the ratio of B(B+-->eta'K+)/B(B0-->eta'K0)=1.17+/-0.08(stat)+/-0.03(syst) and measure the direct CP asymmetries for the charged modes. 相似文献
997.
Jiro Adachi 《Israel Journal of Mathematics》2010,179(1):29-56
In this paper, we study special multi-flags on manifolds. A special multiflag is a certain nested sequence of subbundles of the tangent bundle which are derived by Lie brackets. A property of a special
multi-flag is characterized by the existence of a completely integrable subdistribution of corank one in the largest distribution
in the sequence, which is a so-called covariant subdistribution. It is proved that a one-parameter deformation of a special multi-flag on a compact manifold can be described by a family
of global diffeomorphisms of the underlying manifold, if the covariant subdistribution of the largest distribution in the
flag is preserved. 相似文献
998.
Seiji Nishioka 《Aequationes Mathematicae》2010,79(1-2):1-12
In this paper we prove that solutions of q-P(A 7) are all transcendental over C(t). We also investigate transcendence of solutions of q-P(A 6) and prove transcendence of hypergeometric solutions of q-P(A 6). 相似文献
999.
Kurihara Momo Yasutaka Tetsuo Aono Tatsuo Ashikawa Nobuo Ebina Hiroyuki Iijima Takeshi Ishimaru Kei Kanai Ramon Karube Zin’ichi Konnai Yae Kubota Tomijiro Maehara Yuji Maeyama Takeshi Okizawa Yusuke Ota Hiroaki Otosaka Shigeyoshi Sakaguchi Aya Tagomori Hisaya Taniguchi Keisuke Tomita Masatoshi Tsukada Hirofumi Hayashi Seiji Lee Sangyoon Miyazu Susumu Shin Moono Nakanishi Takahiro Nishikiori Tatsuhiro Onda Yuichi Shinano Takuro Tsuji Hideki 《Journal of Radioanalytical and Nuclear Chemistry》2019,322(2):477-485
Journal of Radioanalytical and Nuclear Chemistry - We assessed the repeatability and reproducibility of methods for determining low dissolved radiocesium concentrations in freshwater in Fukushima.... 相似文献
1000.
Keiko Kokeyama June Gyu Park Kyuman Cho Shin Kirii Tomotada Akutsu Masayuki Nakano Shogo Kambara Kunihiko Hasegawa Naoko Ohishi Kohei Doi Seiji Kawamura 《Physics letters. A》2018,382(29):1950-1955
Recently, a folded Mach–Zehnder interferometer with homodyne in- and quadrature-phase detection was proposed as a high-precision, wide-dynamic range tilt sensor. By way of a practical application and to validate actual performance, two-axis tilt sensors were developed and installed for one mirror of the input mode cleaner cavity in KAGRA, the large-scale cryogenic gravitational-wave telescope in Kamioka, Gifu, Japan. Building on previous work, we have demonstrated that the two-axis tilt sensor has properly sensed the tilt angle changes of the mirror motion with high precision and without calibration. Compared with our initial angular sensor, an optical lever, which is calibrated by using the interferometer tilt sensor, we found that both sensors showed actual tilt motions of the mirror at low frequencies, and the two-axis interferometer sensor has a better sensitivity at higher frequencies. 相似文献