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排序方式: 共有881条查询结果,搜索用时 15 毫秒
191.
Janine Richter Saioa Elordui-Zapatarietxe Håkan Emteborg Ina Fettig Julie Cabillic Enrica Alasonati Fanny Gantois Claudia Swart Taner Gokcen Murat Tunc Burcu Binici Andres Rodriguez-Cea Tea Zuliani Adriana Gonzalez Gago Daniel Pröfrock Marjaana Nousiainen George Sawal Mirella Buzoianu Rosemarie Philipp 《Accreditation and quality assurance》2016,21(2):121-129
The European Water Framework Directive 2000/60/EC requires monitoring of organic priority pollutants in so-called whole water samples, i.e. in aqueous non-filtered samples that contain natural colloidal and suspended particulate matter. Colloids and suspended particles in the liquid phase constitute a challenge for sample homogeneity and stability. Within the joint research project ENV08 “Traceable measurements for monitoring critical pollutants under the European Water Framework Directive 2000/60/EC”, whole water test materials were developed by spiking defined amounts of aqueous slurries of ultra-finely milled contaminated soil or sediment and aqueous solutions of humic acid into a natural mineral water matrix. This paper presents the results of an European-wide interlaboratory comparison (ILC) using this type of test materials. Target analytes were tributyltin, polybrominated diphenyl ethers and polycyclic aromatic hydrocarbons in the ng/L concentration range. Results of the ILC indicate that the produced materials are sufficiently homogeneous and stable to serve as samples for, e.g. proficiency testing or method validation. To our knowledge, this is the first time that ready-to-use water materials with a defined amount of suspended particulate and colloidal matter have been applied as test samples in an interlaboratory exercise. These samples meet the requirements of the European Water Framework Directive. Previous proficiency testing schemes mainly employed filtered water samples fortified with a spike of the target analyte in a water-miscible organic solvent. 相似文献
192.
Comparing the 2,2′‐Biphenylenedithiophosphinate Binding of Americium with Neodymium and Europium 下载免费PDF全文
Dr. Justin N. Cross Dr. Joseph A. Macor Dr. Jeffery A. Bertke Dr. Maryline G. Ferrier Dr. Gregory S. Girolami Dr. Stosh A. Kozimor Joel R. Maassen Dr. Brian L. Scott Dr. David K. Shuh Dr. Benjamin W. Stein Prof. Dr. S. Chantal E. Stieber 《Angewandte Chemie (International ed. in English)》2016,55(41):12755-12759
Advancing our understanding of the minor actinides (Am, Cm) versus lanthanides is key for developing advanced nuclear‐fuel cycles. Herein, we describe the preparation of (NBu4)Am[S2P(tBu2C12H6)]4 and two isomorphous lanthanide complexes, namely one with a similar ionic radius (i.e., NdIII) and an isoelectronic one (EuIII). The results include the first measurement of an Am?S bond length, with a mean value of 2.921(9) Å, by single‐crystal X‐ray diffraction. Comparison with the EuIII and NdIII complexes revealed subtle electronic differences between the complexes of AmIII and the lanthanides. 相似文献
193.
Silvestr Prát 《Colloid and polymer science》1926,40(3):248-251
Ohne Zusammenfassung 相似文献
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Alexandre Picot Cyril Barsu Boris Le Guennic Chantal Andraud Olivier Maury 《Tetrahedron》2008,64(2):399-411
A series of 2,6- and 4-functionalized dipicolinic acid, ester, or amide featuring π-conjugated substituents such as donor-(phenyl or fluorenyl)-acetylene groups have been synthesized. Four crystallographic structures are reported. The influence of the substituent position, the nature of the donor group, and the conjugated backbone as well as the role of the pyridinic side arms on the absorption and emission properties are studied and discussed on the basis of TD-DFT calculations. 相似文献
196.
Insaf Abdouli Frederic Dappozze Marion Eternot Chantal Guillard Nadine Essayem 《Molecules (Basel, Switzerland)》2022,27(23)
In this paper, evidence is provided that the model reaction of aqueous dihydroxyacetone (DHA) conversion is as sensitive to the TiO2 catalysts’ basicity as to their acidity. Two parallel pathways transformed DHA: while the pathway catalyzed by Lewis acid sites gave pyruvaldehyde (PA) and lactic acid (LA), the base-catalyzed route afforded fructose. This is demonstrated on a series of six commercial TiO2 samples and further confirmed by using two reference catalysts: niobic acid (NbOH), an acid catalyst, and a hydrotalcite (MgAlO), a basic catalyst. The original acid-base properties of the six commercial TiO2 with variable structure and texture were investigated first by conventional methods in gas phase (FTIR or microcalorimetry of pyridine, NH3 and CO2 adsorption). A linear relationship between the initial rates of DHA condensation into hexoses and the total basic sites densities is highlighted accounting for the water tolerance of the TiO2 basic sites whatever their strength. Rutile TiO2 samples were the most basic ones. Besides, only the strongest TiO2 Lewis acid sites were shown to be water tolerant and efficient for PA and LA formation. 相似文献
197.
Using the general connection between the upper limit on the neutrino mass and the upper limits on certain types of non-standard-model interactions that can generate loop corrections to the neutrino mass, we derive constraints on some non-standard-model d --> ue- nu interactions. When cast into limits on n --> pe- nu coupling constants, our results yield constraints on scalar and tensor weak interactions improved by more than an order of magnitude over the current experimental limits. When combined with the existing limits, our results yield absolute value(C(S)/C(V)) approximately < 5 x 10(-3), absolute value(C'(S)/C(V)) approximately < 5 x 10(-3), absolute value(C(T)/C(A)) approximately < 1.2 x 10(-2), and absolute value(C'(T)/C(A)) approximately < 1.2 x 10(-2). 相似文献
198.
Spectroscopic constants of the ground and next seven low-lying excited states of diatomic molecules CO, N2, P2, and ScF were computed using the density functional theory SAOP/ATZP model, in conjunction with time-dependent density functional theory (TD-DFT) and a recently developed Slater type basis set, ATZP. Spectroscopic constants, including the equilibrium distances r(e), harmonic vibrational frequency omega(e), vibrational anharmonicity omega(e)x(e), rotational constant B(e), centrifugal distortion constant D(e), the vibration-rotation interaction constant alpha(e), and the vibrational zero-point energy E(n)0 were generated in an effort to establish a reliable database for electron spectroscopy. By comparison with experimental values and a similar model with an established larger Slater-type basis set, et-QZ3P-xD, it was found that this model provides reliably accurate results at reduced computational costs, for both the ground and excited states of the molecules. The over all errors of all eight lowest lying electronic states of the molecules under study using the effective basis set are r(e)(+/-4%), omega(e)(+/-5% mostly without exceeding +/-20%), omega(e)x(e)(+/-5% mostly without exceeding 20%, much more accurate than a previous study on this constant of +/-30%), B(e)(+/-8%), D(e)(+/-10%), alpha(e)(+/-10%), and E(n)0(+/-10%). The accuracy obtained using the ATZP basis set is very competitive to the larger et-QZ3P-xD basis set in particular in the ground electronic states. The overall errors in r(e), omega(e)x(e), and alpha(e) in the ground states were given by +/-0.7, +/-10.1, and +/-8.4%, respectively, using the efficient ATZP basis set, which is competitive to the errors of +/-0.5, +/-9.2, and +/-9.1%, respectively for those constants using the larger et-QZ3P-xD basis set. The latter basis set, however, needs approximately four times of the CPU time on the National Supercomputing Facilities (Australia). Due to the efficiency of the model (TD-DFT, SAOP and ATZP), it will be readily applied to study larger molecular systems. 相似文献
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