全文获取类型
收费全文 | 2782篇 |
免费 | 96篇 |
国内免费 | 12篇 |
专业分类
化学 | 1867篇 |
晶体学 | 49篇 |
力学 | 56篇 |
数学 | 356篇 |
物理学 | 562篇 |
出版年
2023年 | 22篇 |
2022年 | 26篇 |
2021年 | 53篇 |
2020年 | 59篇 |
2019年 | 56篇 |
2018年 | 39篇 |
2017年 | 31篇 |
2016年 | 88篇 |
2015年 | 60篇 |
2014年 | 69篇 |
2013年 | 160篇 |
2012年 | 195篇 |
2011年 | 225篇 |
2010年 | 99篇 |
2009年 | 77篇 |
2008年 | 172篇 |
2007年 | 139篇 |
2006年 | 174篇 |
2005年 | 149篇 |
2004年 | 111篇 |
2003年 | 74篇 |
2002年 | 79篇 |
2001年 | 42篇 |
2000年 | 35篇 |
1999年 | 32篇 |
1998年 | 20篇 |
1997年 | 19篇 |
1996年 | 28篇 |
1995年 | 33篇 |
1994年 | 24篇 |
1993年 | 33篇 |
1992年 | 23篇 |
1991年 | 23篇 |
1990年 | 20篇 |
1989年 | 23篇 |
1988年 | 13篇 |
1987年 | 20篇 |
1986年 | 30篇 |
1985年 | 29篇 |
1984年 | 13篇 |
1983年 | 19篇 |
1982年 | 24篇 |
1981年 | 13篇 |
1980年 | 17篇 |
1978年 | 19篇 |
1977年 | 27篇 |
1976年 | 24篇 |
1975年 | 26篇 |
1974年 | 13篇 |
1970年 | 12篇 |
排序方式: 共有2890条查询结果,搜索用时 31 毫秒
191.
Graeme W. Carlile Robert A. Keyzers Katrina A. Teske Renaud Robert David E. Williams Roger G. Linington Christopher A. Gray Ryan M. Centko Luping Yan Suzana M. Anjos Heidi M. Sampson Donglei Zhang Jie Liao John W. Hanrahan Raymond J. Andersen David Y. Thomas 《Chemistry & biology》2012,19(10):1288-1299
192.
Justin L. P. Benesch 《Journal of the American Society for Mass Spectrometry》2009,20(3):341-348
Mass spectrometry is fast becoming a vital approach not only for the identification and quantification of proteins, but also
for the study of the noncovalent assemblies they form. Approaches for ionizing, transmitting, and detecting protein complexes
intact in the mass spectrometer are now well established. The challenge has therefore shifted to developing and applying mass
spectrometry approaches to elucidate the structure of such species. A crucial aspect to this goal is inducing their disassembly
in the gas phase to mine information as to their composition and organization. Here the consequences of collisionally activating
protein complexes are illustrated through ion mobility mass spectrometry measurements and discussed in the context of the
current literature. Although a consensus view of the mechanism of dissociation is starting to emerge, it is also clear that
a number of aspects remain unresolved. These outstanding questions and frontier challenges must be addressed if gas-phase
dissociative approaches are to reach their full potential in the study of protein assemblies. 相似文献
193.
Some comments are made concerning the multiple stationary-state patterns found in reaction-diffusion systems, including the Schlögl and Autocatalator models. 相似文献
194.
X-ray diffraction has been used to study the nematic phases of the cis and trans isomers of an elongated molecule containing the cyclobutane group. It has been shown that these nematic phases consist of a mixture of single molecules and overlapping core dimers. It has been found that increasing the temperature of the cis isomer rapidly reduces the dimer population, whereas increasing the temperature of the trans isomer enhances the dimer population. This provides an explanation of the relatively high clearing temperature of the trans isomer. The different temperature dependences of the dimer population in the cis and trans isomers has been explained by a model involving inversion of the cylobutane group. 相似文献
195.
BOT-2 cells (human breast tumor origin) have an impaired ability to utilize exogenous thymidine. Previous studies revealed this deficiency to be the permeation event rather than phosphorylation, since the cells have active thymidine kinase. Chromosome-mediated gene transfer was used to transfer genetic information in the form of metaphase chromosomes, from HeLa-65 cells to the BOT-2 cells, correcting the permease deficiency. Poly-L-ornithine or lipochromes were used for facilitation of chromosome uptake. After selection on HAT medium, transferant clones were isolated at a frequency of 4 x 10(-5) and 1 x 10(-5), respectively. Transferants MGP-1 and MGL-1 are stable after 18 months and have been characterized on the bases of purine and pyrimidine nucleoside uptake, relative thymidine kinase activities, alkaline phosphatase activities, and hydrocortisone-induced alkaline phosphatase activity. MGP-1 demonstrates positive thymidine uptake and incorporates radiolabeled thymidine into DNA. MGL-1 remains thymidine transport-deficient and surveys on HAT by increasing endogenous dihydrofolate reductase activity. Alkaline phosphatase activity in MGL-1 is similar to HeLa-65, 2% of that in BOT-2, and in addition, is inducible 25-30-fold by 3 micro M hydrocortisone. We have separated, genetically, a thymidine permease function from phosphorylation in cells of human origin and have transferred genetic information for the regulation of alkaline phosphatase. 相似文献
196.
197.
198.
Ying Yang Friederike M. Mansfeld Maria Kavallaris Katharina Gaus Richard D. Tilley J. Justin Gooding 《Chemical science》2021,12(7):2558
Impedance spectroscopy is a widely used technique for monitoring cell–surface interactions and morphological changes, typically based on averaged signals from thousands of cells. However, acquiring impedance data at the single cell level, can potentially reveal cell-to-cell heterogeneity for example in response to chemotherapeutic agents such as doxorubicin. Here, we present a generic platform where light is used to define and localize the electroactive area, thus enabling the impedance measurements for selected single cells. We firstly tested the platform to assess phenotypic changes in breast cancer cells, at the single cell level, using the change in the cell impedance. We next show that changes in electrochemical noise reflects instantaneous responses of the cells to drugs, prior to any phenotypical changes. We used doxorubicin and monensin as model drugs and found that both drug influx and efflux events affect the impedance noise signals. Finally, we show how the electrochemical noise signal can be combined with fluorescence microscopy, to show that the noise provides information on cell susceptibility and resistance to drugs at the single cell level. Together the combination of electrochemical impedance and electrochemical noise with fluorescence microscopy provides a unique approach to understanding the heterogeneity in the response of single cells to stimuli where there is not phenotypic change.A light addressable single-cell impedance technique for cell adhesion monitoring and measurement of a cell''s drug response based on electrochemical noise is introduced. 相似文献
199.
Umakanta Tripathy R. Justin Rajesh Prem B. Bisht A. Subrahamanyam 《Journal of Chemical Sciences》2002,114(6):557-564
The excited state absorption cross-section of 5,5′-dichloro-11-diphenyl-amino-3,3′-diethyl-10, 12-ethylinethiatricarbocyanine
perchlorate (IR140) have been measured by using a single beam transmission technique. Z-scan experiments have been used to find out a few nonlinear
parameters. The excited state relaxation times have also been measured by using laser induced transient grating (LITG) technique. 相似文献
200.