全文获取类型
收费全文 | 683篇 |
免费 | 17篇 |
国内免费 | 4篇 |
专业分类
化学 | 517篇 |
晶体学 | 8篇 |
力学 | 3篇 |
数学 | 64篇 |
物理学 | 112篇 |
出版年
2023年 | 5篇 |
2022年 | 7篇 |
2021年 | 9篇 |
2020年 | 15篇 |
2019年 | 13篇 |
2018年 | 6篇 |
2017年 | 18篇 |
2016年 | 10篇 |
2015年 | 13篇 |
2014年 | 18篇 |
2013年 | 52篇 |
2012年 | 62篇 |
2011年 | 48篇 |
2010年 | 29篇 |
2009年 | 25篇 |
2008年 | 42篇 |
2007年 | 46篇 |
2006年 | 36篇 |
2005年 | 48篇 |
2004年 | 21篇 |
2003年 | 29篇 |
2002年 | 16篇 |
2001年 | 7篇 |
2000年 | 8篇 |
1999年 | 13篇 |
1998年 | 4篇 |
1997年 | 5篇 |
1996年 | 8篇 |
1995年 | 2篇 |
1994年 | 6篇 |
1993年 | 2篇 |
1992年 | 3篇 |
1991年 | 1篇 |
1990年 | 5篇 |
1989年 | 1篇 |
1988年 | 3篇 |
1987年 | 2篇 |
1986年 | 2篇 |
1985年 | 13篇 |
1984年 | 12篇 |
1983年 | 2篇 |
1982年 | 11篇 |
1981年 | 4篇 |
1980年 | 2篇 |
1979年 | 13篇 |
1978年 | 1篇 |
1977年 | 3篇 |
1975年 | 1篇 |
1974年 | 1篇 |
1973年 | 1篇 |
排序方式: 共有704条查询结果,搜索用时 31 毫秒
151.
152.
Masakazu Nihei 《International Journal of Mathematical Education in Science & Technology》2013,44(4):608-611
In this note, continuous solutions of the following two functional equations are considered by using the definite integral: f(x + y) + f(x 相似文献
153.
Inami Wataru Fukuta Masahiro Masuda Yuriko Nawa Yasunori Ono Atsushi Lin Sheng Kawata Yoshimasa Terakawa Susumu 《Optical Review》2015,22(2):354-358
Optical Review - A plastic scintillator film for use in an electron beam excitation-assisted (EXA) optical microscope is characterized. The thin film scatters an incident electron beam weakly and... 相似文献
154.
Wataru Takahashi Ngai-Ching Wong Jen-Chih Yao 《Numerical Functional Analysis & Optimization》2013,34(1):85-98
Recently, two retractions (projections), which are different from the metric projection and the sunny nonexpansive retraction in a Banach space, were found. In this article, using nonlinear analytic methods and new retractions, we prove a nonlinear ergodic theorem for positively homogeneous and nonexpansive mappings in a uniformly convex Banach space. The limit points are characterized by using new retractions. 相似文献
155.
156.
Fujita M Hattori W Sano T Baba M Someya H Miyazaki K Kamijo K Takahashi K Kawaura H 《Journal of chromatography. A》2006,1111(2):200-205
We have developed a high-throughput, two-dimensional-mapping (isoelectric point [pI], mass-to-charge ratio [m/z]) method by combining a capillary isoelectric focusing chip sealed with removable resin tape and a matrix-assisted laser desorption/ionization time-of-flight mass spectrometer. Sample proteins are separated in a meandering channel on the chip and immediately frozen. The tape is then removed and the proteins are freeze-dried. The freeze-drying maintains the separation state of the proteins and prevents movement of the sample solution, which can reduce pI resolution. A matrix solution is then applied and mass spectrometry is carried out by laser irradiation. The whole process takes less than 70 min, more than 10 times faster than with two-dimensional, polyacrylamide gel electrophoresis. 相似文献
157.
An efficient and versatile synthesis of acylpolyamine spider toxins of all structural types classified by extensive MS analysis has been achieved. By using 2-nitrobenzenesulfonamide as an effective activating and/or protecting group (the Nosyl strategy), the naturally occurring toxins 1-8 corresponding to Types A-F were concisely synthesized in high overall yield. 相似文献
158.
Liang TT Naitoh Y Horikawa M Ishida T Mizutani W 《Journal of the American Chemical Society》2006,128(42):13720-13726
For obtaining molecular devices using metal-molecule-metal junctions, it is necessary to fabricate a steady conductive bridge-structure; that is stable chemical bonds need to be established from a single conductive molecule to two facing electrodes. In the present paper, we show that the steadiness of a conductive bridge-structure depends on the molecular structure of the bridge molecule for nanogap junctions using three types of modified oligo(phenylene vinylene)s (OPVs): alpha,omega-bis(thioacetate) oligo(phenylene vinylene) (OPV1), alpha,omega-bis(methylthioacetate) oligo(phenylene vinylene) (OPV2), and OPV2 consisting of ethoxy side chains (OPV3). We examined the change in resistance between the molecule-bridged junction and a bare junction in each of the experimental Au-OPV-Au junctions to confirm whether molecules formed steady bridges. Herein, the outcomes of whether molecules formed steady bridges were defined in terms of three types of result; successful, possible and failure. We define the ratio of the number of successful junctions to the total number of experimental junctions as successful rate. A 60% successful rate for OPV3 was higher than for the other two molecules whose successful rates were estimated to be approximately 10%. We propose that conjugated molecules consisting of methylthioacetate termini and short alkoxy side chains are well suited for fabricating a steady conductive bridge-structure between two facing electrodes. 相似文献
159.
Ode H Neya S Hata M Sugiura W Hoshino T 《Journal of the American Chemical Society》2006,128(24):7887-7895
Human immunodeficiency virus type 1 protease (HIV-1 PR) is one of the proteins that currently available anti-HIV-1 drugs target. Inhibitors of HIV-1 PR have become available, and they have lowered the rate of mortality from acquired immune deficiency syndrome (AIDS) in advanced countries. However, the rate of emergence of drug-resistant HIV-1 variants is quite high because of their short retroviral life cycle and their high mutation rate. Serious drug-resistant mutations against HIV-1 PR inhibitors (PIs) frequently appear at the active site of PR. Exceptionally, some other mutations such as L90M cause drug resistance, although these appear at nonactive sites. The mechanism of resistance due to nonactive site mutations is difficult to explain. In this study, we carried out computational simulations of L90M PR in complex with each of three kinds of inhibitors and one typical substrate, and we clarified the mechanism of resistance. The L90M mutation causes changes in interaction between the side chain atoms of the 90th residue and the main chain atoms of the 25th residue, and a slight dislocation of the 25th residue causes rotation of the side chain at the 84th residue. The rotation of the 84th residue leads to displacement of the inhibitor from the appropriate binding location, resulting in a collision with the flap or loop region. The difference in levels of resistance to the three inhibitors has been explained from energetic and structural viewpoints, which provides the suggestion for promising drugs keeping its efficacy even for the L90M mutant. 相似文献
160.
Hoshi K Kawakami J Sato W Sato K Sugawara A Saito Y Yoshida K 《Chemical & pharmaceutical bulletin》2006,54(8):1162-1169
Patients with hyperthyroidism sometimes take much time to receive the final diagnosis. To improve patient QOL, simple screening for hyperthyroidism by thyroid non-specialists at the physical check-up is highly expected. Therefore, we applied both Bayesian-type and SOM-type neural networks since we assured the approach useful in analysing thyroid function diagnosis in the previous work. Routine test (14 parameters) data from 66 subjects with a known diagnosis (18 patients with hyperthyroidism and 48 healthy volunteers) were adopted as learning data, and then 142 individuals who also received the same routine tests at the Tohoku University Hospital were screened to predict patients with hyperthyroidism. Both neural networks using 14 parameters predicted several patients as having hyperthyroidism with high probability, including all three hyperthyroid patients diagnosed later by the physician. Further detailed analysis of the routine test parameters that were important for classification found that screening with a set of three parameters (alkaline phosphatase, serum creatinine and total cholesterol) or plus aspartate aminotransferase allowed for quite accurate screening. These results showed that the same neural networks as previous work allows simple screening of patients for hyperthyroidism on the basis of routine test data, and that physicians not specializing in the thyroid can rapidly identify individuals suspected of having hyperthyroidism, to permit a rapid referral for examination and treatment by thyroid specialists. 相似文献