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971.
Alexandre Seyer Anne Riu Laurent Debrauwer Nathalie Bourgès-Abella Alain Brunelle Olivier Laprévote Daniel Zalko 《Journal of the American Society for Mass Spectrometry》2010,21(11):1836-1845
Deca-bromo-diphenyl ether (DBDE) is one of the most efficient brominated flame retardant (BFR) available on the market. We
recently demonstrated that when administered to female rat by oral route, DBDE is efficiently absorbed, with the highest residual
concentrations found in two endocrine glands, namely the adrenal glands and the ovaries. Tinie-of-flight secondary ion mass
spectrometry (TOF-SIMS) imaging, a technique usually used for the study of endogenous compounds, was applied for the first
time to a persistent organic pollutant, allowing to detect and to precisely localize DBDE residues in these two target tissues.
The detection of the bromide ion (81Br isotope) by TOF-SIMS mass spectrometry imaging allowed us to demonstrate a marked cortical tropism of DBDE residues for
the adrenal glands in female rats dosed per os 2 mg · kg−1 DBDE, daily, over 96 h. In ovaries, DBDE residues were found to be concentrated in spots corresponding to part of the corpora
lutea. Hepatic residues of DBDE were found to be homogeneously distributed. Due to the intrinsic toxicity of DBDE, its accumulation
in the adrenal glands and the ovaries may be connected to the mechanisms of actions by which DBDE could trigger endocrine
disruption in mammals. 相似文献
972.
973.
A microfluidic device with integrated fluorimetric detection for flow injection analysis 总被引:1,自引:0,他引:1
Alexandre Fonseca Ivo M. Raimundo Jr. Jarbas J. R. Rohwedder Renato S. Lima Mário C. Ugulino Araújo 《Analytical and bioanalytical chemistry》2010,396(2):715-723
This work describes the development of flow analysis microsystems with integrated fluorimetric detection cells. Channels (width
of 300–540 μm and depth of 200–590 μm) were manufactured by deep-UV lithography in urethane–acrylate (UA) resin. Plastic optical
fibers (diameter of 250 μm) were coupled to a 2.0-mm-long detection channel in order to guide the excitation radiation from
an LED (470 nm) and collect the emitted radiation at a right angle towards a photomultiplier. A single-line miniaturized system,
with a total internal volume of 10.4 μL, was evaluated by means of standard fluorescein solutions (0.53–2.66 μmol L−1, pH 8.5). The analytical signals presented a linear relationship in the concentration range studied, with a relative standard
deviation of 1.9% (n = 5), providing a detection limit of 0.37 μmol L−1 and an analytical frequency of 60 samples/h, using a flow rate of 60 μL min−1. Optical microscopy images and videos acquired in real time for the hydrodynamic injection of 130 and 320 nL of sample solutions
indicated the good performance of the proposed sampling strategy. Another microsystem with a total internal volume of 38 μL
was developed, incorporating a confluence point for two solutions. This device was applied to the determination of the total
concentration of Ca2+ and Mg2+ in commercial mineral waters using the calcein method. Microscopy images and videos demonstrated the mixing efficiency of
the solutions in the microchannels. A linear relationship was observed for the analytical signal in the Ca2+ concentration range from 25 to 125 μmol L−1, with relative standard deviations of 3.5%. The analysis of mineral waters with the proposed system provided results that
did not differ significantly from those obtained by the EDTA titration method at a confidence level of 95%. These results
demonstrate the viability of developing micro flow injection systems with an integrated fluorimetric detection cell.
相似文献
974.
Carlo Giansante Alexandre G. L. Olive Christian Schäfer Guillaume Raffy André Del Guerzo 《Analytical and bioanalytical chemistry》2010,396(1):125-131
Time-resolved confocal fluorescence microscopy is used to image and analyze quantitatively the influence of 1,3,5-trinitrobenzene
on the fluorescence of organic nanofibers. These nanofibers are formed by self-assembly of 2,3-didecyloxyanthracene in methanol
or from solutions drop-casted onto glass surfaces. Amplification of the fluorescence quenching emerges in the nanofibers as
compared to the constituting monomer thus leading to efficient detection of nanomolar concentrations of TNB. The emission
of dry nanofibers on glass is also efficiently quenched by vapors of TNB. 相似文献
975.
Farida Benabdellah Alexandre Seyer Loïc Quinton David Touboul Alain Brunelle Olivier Laprévote 《Analytical and bioanalytical chemistry》2010,396(1):151-162
Mass spectrometry imaging is becoming a more and more widely used method for chemical mapping of organic and inorganic compounds
from various surfaces, especially tissue sections. Two main different techniques are now available: matrix-assisted laser
desorption/ionizaton, where the sample, preliminary coated by an organic matrix, is analyzed by a UV laser beam; and secondary
ion mass spectrometry, for which the target is directly submitted to a focused ion beam. Both techniques revealed excellent
performances for lipid mapping of tissue surfaces. This article will discuss similarities, differences, and specificities
of ion images generated by these two techniques in terms of sample preparation, sensitivity, ultimate spatial resolution,
and structural analysis. 相似文献
976.
977.
Newly obtained data on the critical dynamics of the drifting/fracturing sea ice in the Arctic Ocean were analyzed and compared with published data on the dynamic processes in the Earth’s crust. Substantial similarities were found in the scaling behavior of both geophysical systems; the most important of them is the b-value space/time variability including a pre-failure drop of this parameter. The b-value pattern of the ensemble of drifting ice floes is an analogue of the b-value distribution over areas and depths in tectonic structures. A common feature of the pre-failure state in the cryosphere and in the Earth’s crust is the increased degree of the energy conservation that manifests itself both in the sea ice consolidation prior to basin-wide ice pack fragmentations, and in involving harder geological formations in the fracture process before earthquakes, respectively. From the viewpoint of the conservative SOC concept, this relation between the system’s conservativity and the occurrence of large-scale fracture events means that the expected scale level of failure is determined by the system’s closeness to “true” SOC behavior. 相似文献
978.
Avelino Corma Prof. Maria T. Navarro Dr. Fernando Rey Prof. Violeta R. Ruiz Maria J. Sabater Dr. 《Chemphyschem》2009,10(7):1084-1089
A direct route : Silylated triphenylmethanol is incorporated into mesoporous material MCM‐41 through a direct synthesis method. Under acidic conditions, this inorganic–organic hybrid generates trityl cations to give the photoactive material Tyl‐MCM41. Tyl‐MCM41 promotes the photosensitized dimerization of 1,3‐cyclohexadiene with an unprecedented selectivity towards the formation of the exo product (see scheme).
979.
Francis Canon Franck Paté Emmanuelle Meudec Thérèse Marlin Véronique Cheynier Alexandre Giuliani Pascale Sarni-Manchado 《Analytical and bioanalytical chemistry》2009,395(8):2535-2545
Numerous protein–polyphenol interactions occur in biological and food domains particularly involving proline-rich proteins,
which are representative of the intrinsically unstructured protein group (IUP). Noncovalent protein–ligand complexes are readily
detected by electrospray ionization mass spectrometry (ESI-MS), which also gives access to ligand binding stoichiometry. Surprisingly,
the study of interactions between polyphenolic molecules and proteins is still an area where ESI-MS has poorly benefited,
whereas it has been extensively applied to the detection of noncovalent complexes. Electrospray ionization mass spectrometry
has been applied to the detection and the characterization of the complexes formed between tannins and a human salivary proline-rich
protein (PRP), namely IB5. The study of the complex stability was achieved by low-energy collision-induced dissociation (CID)
measurements, which are commonly implemented using triple quadrupole, hybrid quadrupole time-of-flight, or ion trap instruments.
Complexes composed of IB5 bound to a model polyphenol EgCG have been detected by ESI-MS and further analyzed by MS/MS. Mild
ESI interface conditions allowed us to observe intact noncovalent PRP–tannin complexes with stoichiometries ranging from 1:1
to 1:5. Thus, ESI-MS shows its efficiency for (1) the study of PRP–tannin interactions, (2) the determination of stoichiometry,
and (3) the study of complex stability. We were able to establish unambiguously both their stoichiometries and their overall
subunit architecture via tandem mass spectrometry and solution disruption experiments. Our results prove that IB5·EgCG complexes
are maintained intact in the gas phase.
相似文献
980.
Stefan Ankirchner Peter Imkeller Alexandre Popier 《Stochastic Processes and their Applications》2009,119(9):2744-2772
We consider backward stochastic differential equations (BSDEs) with nonlinear generators typically of quadratic growth in the control variable. A measure solution of such a BSDE will be understood as a probability measure under which the generator is seen as vanishing, so that the classical solution can be reconstructed by a combination of the operations of conditioning and using martingale representations. For the case where the terminal condition is bounded and the generator fulfills the usual continuity and boundedness conditions, we show that measure solutions with equivalent measures just reinterpret classical ones. For the case of terminal conditions that have only exponentially bounded moments, we discuss a series of examples which show that in the case of non-uniqueness, classical solutions that fail to be measure solutions can coexist with different measure solutions. 相似文献