全文获取类型
收费全文 | 8362篇 |
免费 | 204篇 |
国内免费 | 30篇 |
专业分类
化学 | 6339篇 |
晶体学 | 110篇 |
力学 | 130篇 |
数学 | 583篇 |
物理学 | 1434篇 |
出版年
2022年 | 63篇 |
2021年 | 72篇 |
2020年 | 87篇 |
2019年 | 110篇 |
2018年 | 75篇 |
2017年 | 64篇 |
2016年 | 146篇 |
2015年 | 131篇 |
2014年 | 170篇 |
2013年 | 401篇 |
2012年 | 429篇 |
2011年 | 466篇 |
2010年 | 269篇 |
2009年 | 252篇 |
2008年 | 491篇 |
2007年 | 507篇 |
2006年 | 529篇 |
2005年 | 470篇 |
2004年 | 418篇 |
2003年 | 364篇 |
2002年 | 326篇 |
2001年 | 148篇 |
2000年 | 121篇 |
1999年 | 110篇 |
1998年 | 74篇 |
1997年 | 112篇 |
1996年 | 123篇 |
1995年 | 71篇 |
1994年 | 82篇 |
1993年 | 74篇 |
1992年 | 78篇 |
1991年 | 81篇 |
1990年 | 58篇 |
1989年 | 49篇 |
1988年 | 70篇 |
1987年 | 65篇 |
1986年 | 60篇 |
1985年 | 117篇 |
1984年 | 127篇 |
1983年 | 75篇 |
1982年 | 105篇 |
1981年 | 103篇 |
1980年 | 92篇 |
1979年 | 100篇 |
1978年 | 88篇 |
1977年 | 74篇 |
1976年 | 83篇 |
1975年 | 62篇 |
1974年 | 53篇 |
1973年 | 73篇 |
排序方式: 共有8596条查询结果,搜索用时 15 毫秒
61.
Assembly of submicron-sized microspheres has received much attention due to its high potential for wide variety of applications. We have developed a preparation method of polymer particles by simple mixing of a poor solvent into the polymer solution followed by evaporation of a good solvent. By using this technique, silica nanoparticles and polymer composite particles were prepared. Preparation of three-dimensional assemblies of silica particles in polymer particles and composite Janus particles are shown. 相似文献
62.
63.
64.
65.
More often than not, models of flavor symmetry rely on the use of nonrenormalizable operators (in the guise of flavons) to accomplish the phenomenologically successful tribimaximal mixing of neutrinos. We show instead how a simple renormalizable two-parameter neutrino mass model of tribimaximal mixing can be constructed with the non-Abelian discrete symmetry T(7) and the gauging of B-L. This is also achieved without the addition of auxiliary symmetries and particles present in almost all other proposals. Most importantly, it is verifiable at the Large Hadron Collider. 相似文献
66.
Ohwada K Fujii Y Katsuki Y Muraoka J Nakao H Murakami Y Sawa H Ninomiya E Isobe M Ueda Y 《Physical review letters》2005,94(10):106401
The present resonant x-ray scattering has been performed on a monoclinically split single domain of NaV(2)O(5). The observation of a critically enhanced contrast between V(4+) and V(5+) ions has led us to the unequivocal conclusion of the charge-order pattern of the low-temperature phase of NaV(2)O(5) below T(c) = 35 K. In spite of the possible four types of configuration of the zigzag-type charge-order patterns in the ab plane (A,A',B and B'), the stacking sequence along the c axis is determined as the AAA'A' type by comparison with model calculations. 相似文献
67.
Motivated by recent Hall-effect experiment in YbRh(2)Si(2), we study ground state properties of a Kondo lattice model in a two-dimensional square lattice using variational Monte Carlo method. We show that there are two types of phase transition, an antiferromagnetic transition and a topological one (Fermi-surface reconstruction). In a wide region of parameters, these two transitions occur simultaneously without the breakdown of Kondo screening, accompanied by a discontinuous change of the Hall coefficient. This result is consistent with the experiment and gives a novel theoretical picture for the quantum critical point in heavy-fermion systems. 相似文献
68.
Makoto Kimura Kasumi Kashikura Satomi Yokoi Yumiko Koiwa Yoshikazu Tokuoka Norimichi Kawashima 《Optical Review》2005,12(3):207-210
We determined photodynamic therapy (PDT) efficacy using a flash wave (FW) and a continuous wave (CW) light, of which the fluence rate was 70 W/cm2, for murine thymic lymphoma cells (EL-4) cultivated in vitro. The irradiation frequency and the pulse width of the FW light were in the range of 1–32 Hz and less than one millisecond, respectively. 5-Aminolevulinic acid-induced protoporphyrin IX (ALA-PpIX) was used as a photosensitizer. When EL-4 with ALA administration was irradiated by the light for 4 h (irradiation fluence: 1.0J/cm2), the survival rate of EL-4 by the FW light was lower than that by the CW light, except for the FW light with irradiation frequency of 32 Hz, and decreased gradually with decreasing irradiation frequency. Moreover, the FW light, especially at lower irradiation frequency, was superior to the CW light for the generation of singlet oxygen in an aqueous PpIX solution. Therefore, thehigher PDT efficacy for EL-4 of the FW light would be caused by the greater generation of singlet oxygen in the cells. 相似文献
69.
Takahide Y Konoike T Enomoto K Nishimura M Terashima T Uji S Yamamoto HM 《Physical review letters》2006,96(13):136602
The current-voltage characteristics of layered organic crystals theta-(BEDT-TTF)2MZn(SCN)4 (M = Cs, Rb) follow the power law with a large exponent (e.g., 8.4 at 0.29 K for M = Cs) over a wide range of currents in the low-temperature insulating state. The power-law characteristics are attributed to electric field-induced unbinding of electron-hole pairs that are thermally excited in the background of the two-dimensional charge order. The magnitude of crossover electric fields from Ohmic to the power-law characteristics indicates that the electron-electron Coulomb interaction is significantly long-ranged: The screening length is greater than 10 molecule sites. 相似文献
70.
Yoshiteru Akezaki Shunichi Yasuda Katumi Hamaoka Yoshinobu Yoshimoto Susumu Yoshimura Takuo Nomura Hiroshi Yamasaki Atushi Sato 《Physical Therapy Research》2009,12(1):9-12
Purpose: The obstacle negotiation gait (ONG) is a fundamental activity of daily living. In cerebrovascular hemiplegic patients (stroke patients), the weight-bearing rate (WBR) on the paretic limb necessary for an independent ONG was studied. Methods: One hundred and seventeen stroke patients were involved. The patients'' average age at the time of the study was 67 years, and the average time from stroke onset was 102 days. There were 68 men and 49 women. Seventy patients were right hemiplegics, and 47 were left hemiplegics. The correlations between ONG and age, sex, body mass index (BMI), time from stroke onset, muscle strength of both the paretic and non-paretic limbs, Brunnstrom stage of the lower limbs, deep sensation, and the WBR on both the paretic and non-paretic limbs were studied. Patients who could perform ONG independently and safely were categorized as the independent group (IG), and those who needed observation or any assistance were categorized as the dependent group (DG). Results: The BMI, muscle strength of both the paretic and non-paretic limbs, Brunnstrom stage of the lower limbs, deep sensation and the WBR for both the paretic and non-paretic limbs were significantly different between the IG and DG groups. In particular, the WBR on the paretic limb was found to correlate significantly with the ONG, and a WBR value of 80.5% on the paretic limb gave a clear cut-off value. Conclusion: Although multiple factors influenced the ONG of stroke patients, the WBR on the paretic limb was the most influential. 相似文献