全文获取类型
收费全文 | 1043篇 |
免费 | 6篇 |
国内免费 | 11篇 |
专业分类
化学 | 694篇 |
晶体学 | 9篇 |
力学 | 27篇 |
数学 | 180篇 |
物理学 | 150篇 |
出版年
2021年 | 4篇 |
2020年 | 8篇 |
2019年 | 8篇 |
2018年 | 5篇 |
2017年 | 7篇 |
2016年 | 13篇 |
2015年 | 14篇 |
2014年 | 7篇 |
2013年 | 40篇 |
2012年 | 54篇 |
2011年 | 71篇 |
2010年 | 33篇 |
2009年 | 34篇 |
2008年 | 63篇 |
2007年 | 68篇 |
2006年 | 58篇 |
2005年 | 62篇 |
2004年 | 54篇 |
2003年 | 58篇 |
2002年 | 44篇 |
2001年 | 12篇 |
2000年 | 12篇 |
1999年 | 12篇 |
1998年 | 12篇 |
1997年 | 26篇 |
1996年 | 18篇 |
1995年 | 11篇 |
1994年 | 16篇 |
1993年 | 11篇 |
1992年 | 15篇 |
1991年 | 8篇 |
1990年 | 6篇 |
1989年 | 10篇 |
1988年 | 3篇 |
1987年 | 10篇 |
1986年 | 3篇 |
1985年 | 17篇 |
1984年 | 10篇 |
1983年 | 12篇 |
1982年 | 11篇 |
1981年 | 19篇 |
1980年 | 15篇 |
1979年 | 7篇 |
1978年 | 20篇 |
1977年 | 11篇 |
1976年 | 13篇 |
1975年 | 10篇 |
1974年 | 5篇 |
1973年 | 4篇 |
1971年 | 3篇 |
排序方式: 共有1060条查询结果,搜索用时 250 毫秒
91.
Jean-Paul Penot 《Journal of Global Optimization》2008,40(1-3):319-338
We look for a general framework in which the Ekeland duality can be formulated. We propose a scheme in which the parameter
sets are provided with a coupling function which induces a conjugacy. The decision spaces are not supposed to have any special
structure. We examine several examples. In particular, we consider some special classes of generalized convex functions. 相似文献
92.
Tristan A. Reekie Jean-Paul Gisselbrecht Corinne Boudon Nils Trapp François Diederich 《Tetrahedron letters》2017,58(25):2414-2416
Two push-pull chromophores that have shown utility in the field of molecular electronics and non-linear optics are DDMEBT (1, 2-(4-dimethylamino)phenyl)-3-((4-(dimethylamino)phenyl)ethynyl)buta-1,3-diene-1,1,4,4-tetracarbonitrile) and TDMEE (2, 4-(4-dimethylamino)phenyl)but-1-en-3-yne-1,1,2-tricarbonitrile). Unfortunately, the methods reported for their synthesis give variable yields, use toxic solvents, and only provide small amounts of material. We report improved synthetic protocols, providing access to larger quantities of material. By investigating multiple metal-acetylides of 4-ethynyl-N,N-dimethylaniline and their subsequent addition to TCNE, we obtained various products depending on the identity of the metal ion. This led to the simple synthesis of push-pull chromophoric compounds. 相似文献
93.
Montserrat Cortina‐Puig Anastasia C. H. Scangas Zachary S. Marchese Silvana Andreescu Jean‐Louis Marty Carole Calas‐Blanchard 《Electroanalysis》2010,22(20):2429-2433
This paper describes the development of a xanthine oxidase/poly‐m‐phenylenediamine (XOD‐PPD)‐modified electrode. The biosensor was constructed by encapsulating XOD in a sol‐gel matrix deposited onto a platinum based screen‐printed electrode functionalized with a permselective PPD membrane. The hydrogen peroxide generated as a final product of the enzymatic reaction between the hypoxanthine and the XOD or by the spontaneous dismutation of superoxide radicals was selectively monitored at +700 mV. The use of a highly selective PPD layer blocked the nonspecific oxidation of other oxidizable molecules. Finally the biosensor was applied to the determination of the antioxidant capacity of acetylsalicylic acid. 相似文献
94.
95.
Clementine Cailleteau Ludovic Micallef Clemence Lepage Philippe Jean-Paul Cardot Jean-Louis Beneytout Bertrand Liagre Serge Battu 《Analytical and bioanalytical chemistry》2010,398(3):1273-1283
Differentiation therapy could be one strategy for stopping cancer cell proliferation. A plant steroid, diosgenin, is known
to induce megakaryocytic differentiation in human erythroleukemia (HEL) cells. In recent studies, the use of sedimentation
field-flow fractionation (SdFFF) allowed the preparation of subpopulations that may differ in regard to sensitivity to differentiation
induction. The specific goal of this study was to determine the relationship between cell cycle stage and sensitivity to megakaryocytic
differentiation induction of HEL cells. After first confirming the capacity of diosgenin to specifically select targets, hyperlayer
SdFFF cell sorting was used to prepare fractions according to cell cycle position from crude HEL cells. The sensitivities
of these fractions to diosgenin-induced differentiation were then tested. The coupling of SdFFF cell separation to imaging
flow cytometry showed that G1-phase cells were more sensitive to differentiation induction than S/G2M-phase cells, confirming
the relationship between cell status at the start of induction, the extent of the biological event, and the potential of SdFFF
in cancer research. 相似文献
96.
Gaelle Kerric Françoise Zammattio Jean-Paul Quintard 《Journal of organometallic chemistry》2010,695(1):103-3321
An insoluble polymer-supported phenyltin reagent was successfully used in Stille cross-coupling reactions with aryl- and heteroaryl-halides. Cross-coupling products were isolated in good to high yields with very low contamination by tin and palladium residues after removal of the residual supported organotin halide. The regeneration and recyclability of the supported phenyltin reagent were also examined and proved to be possible, but required palladium cleaning of the grafted polymer to be efficient along 4 cycles when Pd(PPh3)4 was used as catalyst. 相似文献
97.
Progressive hedging innovations for a class of stochastic mixed-integer resource allocation problems
Numerous planning problems can be formulated as multi-stage stochastic programs and many possess key discrete (integer) decision
variables in one or more of the stages. Progressive hedging (PH) is a scenario-based decomposition technique that can be leveraged
to solve such problems. Originally devised for problems possessing only continuous variables, PH has been successfully applied
as a heuristic to solve multi-stage stochastic programs with integer variables. However, a variety of critical issues arise
in practice when implementing PH for the discrete case, especially in the context of very difficult or large-scale mixed-integer
problems. Failure to address these issues properly results in either non-convergence of the heuristic or unacceptably long
run-times. We investigate these issues and describe algorithmic innovations in the context of a broad class of scenario-based
resource allocation problem in which decision variables represent resources available at a cost and constraints enforce the
need for sufficient combinations of resources. The necessity and efficacy of our techniques is empirically assessed on a two-stage
stochastic network flow problem with integer variables in both stages. 相似文献
98.
Loire M Simonet V Petit S Marty K Bordet P Lejay P Ollivier J Enderle M Steffens P Ressouche E Zorko A Ballou R 《Physical review letters》2011,106(20):207201
The spin-wave excitations emerging from the chiral helically modulated 120° magnetic order in a langasite Ba?NbFe?Si?O?? enantiopure crystal were investigated by unpolarized and polarized inelastic neutron scattering. A dynamical fingerprint of the chiral ground state is obtained, singularized by (i) spectral weight asymmetries answerable to the structural chirality and (ii) a full chirality of the spin correlations observed over the whole energy spectrum. The intrinsic chiral nature of the spin waves' elementary excitations is shown in the absence of macroscopic time-reversal symmetry breaking. 相似文献
99.
100.
Muriel De Bock Marie-Alice Meuwis Tran Quang Minh Jean-Paul Chapelle Michel Malaise Marianne Fillet 《Talanta》2010,82(1):245-594
In most diseases, the clinical need for serum/plasma markers has never been so crucial, not only for diagnosis, but also for the selection of the most efficient therapies, as well as exclusion of ineffective or toxic treatment. Due to the high sample complexity, prefractionation is essential for exploring the deep proteome and finding specific markers.In this study, three different sample preparation methods (i.e., highly abundant protein precipitation, restricted access materials (RAM) combined with IMAC chromatography and peptide ligand affinity beads) were investigated in order to select the best fractionation step for further differential proteomic experiments focusing on the LMW proteome (MW inferior to 40,000 Da). Indeed, the aim was not to cover the entire plasma/serum proteome, but to enrich potentially interesting tissue leakage proteins. These three methods were evaluated on their reproducibility, on the SELDI-TOF-MS peptide/protein peaks generated after fractionation and on the information supplied.The studied methods appeared to give complementary information and presented good reproducibility (below 20%). Peptide ligand affinity beads were found to provide efficient depletion of HMW proteins and peak enrichment in protein/peptide profiles. 相似文献