全文获取类型
收费全文 | 3761篇 |
免费 | 226篇 |
国内免费 | 13篇 |
专业分类
化学 | 2442篇 |
晶体学 | 10篇 |
力学 | 104篇 |
数学 | 669篇 |
物理学 | 557篇 |
无线电 | 218篇 |
出版年
2024年 | 9篇 |
2023年 | 30篇 |
2022年 | 45篇 |
2021年 | 67篇 |
2020年 | 55篇 |
2019年 | 69篇 |
2018年 | 70篇 |
2017年 | 67篇 |
2016年 | 171篇 |
2015年 | 115篇 |
2014年 | 180篇 |
2013年 | 265篇 |
2012年 | 277篇 |
2011年 | 280篇 |
2010年 | 190篇 |
2009年 | 173篇 |
2008年 | 225篇 |
2007年 | 225篇 |
2006年 | 198篇 |
2005年 | 172篇 |
2004年 | 164篇 |
2003年 | 129篇 |
2002年 | 125篇 |
2001年 | 70篇 |
2000年 | 57篇 |
1999年 | 41篇 |
1998年 | 42篇 |
1997年 | 37篇 |
1996年 | 33篇 |
1995年 | 32篇 |
1994年 | 26篇 |
1993年 | 21篇 |
1992年 | 26篇 |
1991年 | 21篇 |
1990年 | 21篇 |
1989年 | 15篇 |
1988年 | 12篇 |
1987年 | 12篇 |
1986年 | 11篇 |
1985年 | 26篇 |
1984年 | 14篇 |
1983年 | 13篇 |
1982年 | 18篇 |
1981年 | 16篇 |
1980年 | 19篇 |
1979年 | 11篇 |
1978年 | 8篇 |
1977年 | 10篇 |
1976年 | 10篇 |
1934年 | 11篇 |
排序方式: 共有4000条查询结果,搜索用时 15 毫秒
1.
Elise Laszlo Gregory De Crescenzo Alfonso Nieto-Argüello Xavier Banquy Davide Brambilla 《Advanced functional materials》2021,31(46):2106061
The noninvasive sampling of dermal interstitial fluid (ISF) for the monitoring of clinical biomarkers is a greatly appealing area of research. The identification of molecular biomarkers in biological fluids has been accelerated with -omics analyses but remains limited in ISF because of its time-consuming and complex extraction process. Here, the generation of microneedle (MN) patches made of superabsorbent acrylate-based hydrogels for the rapid sampling of dermal ISF is described to explore its proteome. In depth, iterative optimization allows the identification of novel acrylate-based compositions with the required chemical, mechanical, and biocompatibility properties allowing proteomic analysis of the extracted ISF for the first time after sampling with swelling MNs. The generated MN arrays show no cytotoxic effect, successfully cross the stratum corneum, and can collect up to 6 µL of dermal ISF in 10 min in vivo. Proteomics lead to the detection of 176 clinically relevant biomarkers in the collected samples validating the use of ISF as a relevant bodily fluid for disease monitoring and diagnostic. Importantly, it is discovered that extraction fingerprint is strongly dependent on the MNs chemistry, and thus specific biomarkers could be selectively extracted by tuning the composition of the patch, making the system versatile and specific. 相似文献
2.
Matteo Di Giosia Alice Soldà Markus Seeger Andrea Cantelli Fabio Arnesano Maria I. Nardella Vincenzo Mangini Francesco Valle Marco Montalti Francesco Zerbetto Stefania Rapino Matteo Calvaresi Vasilis Ntziachristos 《Advanced functional materials》2021,31(20):2101527
Fullerenes are candidates for theranostic applications because of their high photodynamic activity and intrinsic multimodal imaging contrast. However, fullerenes suffer from low solubility in aqueous media, poor biocompatibility, cell toxicity, and a tendency to aggregate. C70@lysozyme is introduced herein as a novel bioconjugate that is harmless to a cellular environment, yet is also photoactive and has excellent optical and optoacoustic contrast for tracking cellular uptake and intracellular localization. The formation, water-solubility, photoactivity, and unperturbed structure of C70@lysozyme are confirmed using UV-visible and 2D 1H, 15N NMR spectroscopy. The excellent imaging contrast of C70@lysozyme in optoacoustic and third harmonic generation microscopy is exploited to monitor its uptake in HeLa cells and lysosomal trafficking. Last, the photoactivity of C70@lysozyme and its ability to initiate cell death by means of singlet oxygen (1O2) production upon exposure to low levels of white light irradiation is demonstrated. This study introduces C70@lysozyme and other fullerene-protein conjugates as potential candidates for theranostic applications. 相似文献
3.
Dr. Chenge Li Dr. Alison G. Tebo Marion Thauvin Marie-Aude Plamont Prof. Dr. Michel Volovitch Dr. Xavier Morin Prof. Dr. Sophie Vriz Prof. Dr. Arnaud Gautier 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(41):18073-18079
Far-red emitting fluorescent labels are highly desirable for spectral multiplexing and deep tissue imaging. Here, we describe the generation of frFAST (far-red Fluorescence Activating and absorption Shifting Tag), a 14-kDa monomeric protein that forms a bright far-red fluorescent assembly with (4-hydroxy-3-methoxy-phenyl)allylidene rhodanine (HPAR-3OM). As HPAR-3OM is essentially non-fluorescent in solution and in cells, frFAST can be imaged with high contrast in presence of free HPAR-3OM, which allowed the rapid and efficient imaging of frFAST fusions in live cells, zebrafish embryo/larvae, and chicken embryos. Beyond enabling the genetic encoding of far-red fluorescence, frFAST allowed the design of a far-red chemogenetic reporter of protein–protein interactions, demonstrating its great potential for the design of innovative far-red emitting biosensors. 相似文献
4.
5.
It is known that under resonance conditions, a group of strongly interacting bosonic atoms, trapped in a double-well potential, mimics a single particle, performing Rabi oscillations between the wells. By implication, all atoms need to tunnel at roughly the same time, even though the Bose–Hubbard Hamiltonian accounts only for one-atom-at-a-time transfers. The mechanism of this collective behavior is analyzed, the Rabi frequencies in the process are evaluated, and the limitation of this simple picture is discussed. In particular, it is shown that the small rapid oscillations superimposed on the slow Rabi cycle result from splitting the transferred cluster at the sudden onset of tunnelling, and disappear if tunnelling is turned on gradually. 相似文献
6.
7.
Xavier Gerbaux Armand Hadni Michel Josse 《Journal of Infrared, Millimeter and Terahertz Waves》1994,15(5):775-782
Finesse as high as 260 and peak transmission close to 98% at frequencies around 30 cm?1 are predicted at 10 K by coating the Perot-Fabry (PF) mirrors with a suitable thickness of High Tc (HTC) superconductor YBaCuO. In fact, Finesse will be limited by the lack of parallelism and the lack of perfect flatness of the mirrors to values around 100. These predictions are based upon phenomenological models for both the YBaCuO coating and the MgO support, i.e. from direct transmission measurements of MgO and YBaCuO in the Far IR, which had to be fitted by the models. 相似文献
8.
This Note addresses the derivation of an improved On-Surface Radiation Condition for the numerical solution of the exterior Helmholtz equation at high-frequencies. This condition is built as an approximation of the Neumann-to-Dirichlet map by using a local regularization of its principal classical symbol in the gliding zone for modelling the creeping waves. The numerical simulation of this pseudodifferential operator is efficiently realized with a linear cost according to the dimension of the boundary element approximation space using suitable complex Padé approximants. A numerical example is provided. To cite this article: X. Antoine et al., C. R. Acad. Sci. Paris, Ser. I 340 (2005). 相似文献
9.
Frederico Xavier 《Journal of Geometric Analysis》1993,3(5):513-527
The helicoid and the plane are the only known complete simply connected minimal surfaces without self-intersections. In this paper we make an analytic study of this class of surfaces by first deforming them continuously into surfaces with self-intersections. Next, we study the (backward) time evolution of the set of self-intersections and see what geometric conditions must prevail in order for the self-intersections to rush off to infinity in finite time. As a result of this program it is shown that any surface of the type considered above has to satisfy at least one of five geometric possibilities. The first two of these alternatives are pathological, the third one is satisfied by the plane, and the next two are satisfied by the helicoid. 相似文献
10.
We present a new generic problem solving approach for over-constrained problems based on Max-SAT. We first define a Boolean
clausal form formalism, called soft CNF formulas, that deals with blocks of clauses instead of individual clauses, and that allows one to declare each block either as hard (i.e., must be satisfied by any solution) or soft (i.e., can be violated by some solution). We then present two Max-SAT solvers that find a truth assignment that satisfies
all the hard blocks of clauses and the maximum number of soft blocks of clauses. Our solvers are branch and bound algorithms
equipped with original lazy data structures, powerful inference techniques, good quality lower bounds, and original variable
selection heuristics. Finally, we report an experimental investigation on a representative sample of instances (random 2-SAT,
Max-CSP, graph coloring, pigeon hole and quasigroup completion) which provides experimental evidence that our approach is
very competitive compared with the state-of-the-art approaches developed in the CSP and SAT communities.
Research partially supported by projects TIN2004-07933-C03-03 and TIC2003-00950 funded by the Ministerio de Educación y Ciencia. The second author is supported by a grant Ramón y Cajal. 相似文献