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311.
Truncated, six-sided single crystals of a 10–16 linear polyester were grown from dilute solution in hexanol, deposited onto Mylar film, and uniaxially deformed at room temperature. For elongations below 10%, the crystals deform uniformly; however, above 20% elongation many cracks spanned by fibrils of 300 Å diameter develop approximately normal to the applied stress direction. Depending on the position of the crystal relative to the draw direction, lateral buckling pleats and cleavage cracks can also occur. Collapse of the nonplanar crystals onto the substrate with a resulting nonuniform adherence of the crystal influences the deformation. The deformation morphology is compared to that of truncated sixfold sector polyethylene crystals. Most notably, in contrast to polyethylene, {010} fold sectors do not deform differently from {110} fold sectors and phase boundaries between {110} and {010} fold sectors do not fracture easily. 相似文献
312.
313.
314.
Wall K.F. Aggarwal R.L. Fahey R.E. Strauss A.J. 《Quantum Electronics, IEEE Journal of》1988,24(6):1016-1020
A small-signal single-pass power gain of e 5.2=180 has been measured for a signal in the π polarization at 790.7 nm in a longitudinally pumped Ti:Al2O 3 amplifier. A double-pass power gain of e 5.2 ≈104 has been attained for the same polarization at 799.8 nm. The ratio of the gain cross sections at 632.8 and 790.7 nm is 1/25. The gain anisotropy at 632.8 nm is g π/g σ=2.3. The lifetime of the upper lasing level decreases with increased pumping, probably as the result of amplified spontaneous emission 相似文献
315.
Condensation of bis(2-furanthiocarboxyhydradatometal(II), M(fth)2; [M (II) = Mn, Fe, Co, Ni, Cu and Zn] with pyridine-2- and -4-carboxaldehydes gave complexes of the formula M(pfth)2 [pfth? = pyridine-2-carboxaldehyde-2-furanthiocarboxyhydrazonato], Ni(Ifth)2, Zn(Ifth)2, Cu(Ifth) and Co(Ifth)3, (Ifth? = pyridine-4-carboxaldehyde-2-furanthiocarboxyhydrazonato). The magnetic and electronic spectral studies coupled with photoacoustic or Mössbauer spectra suggested octahedral geometry for the M(II) complexes with low-spin states for Co(Ifth)3 and Fe(pfth)2. IR and 1H NMR spectral studies of diamagnetic complexes suggested bonding through “azomethine” nitrogen and “thiolo” sulphur. IR spectra also showed the involvement of pyridine ring nitrogen in coordination in all the complexes except Cu(Itfh), Co(Ifth)3, and Zn(Ifth)2. Some of the compounds possessed antimicrobial activity. 相似文献
316.
Suresh Chandra 《Mathematical Methods of Operations Research》1970,14(1):297-301
Summary A theorem on supports of a convex functional in a realBanach space is proved which provides us with the principal tool to establish certain duality results for a non-linear programming problem in a realBanach space.
Vorgel. v.:J. Nitsche. 相似文献
Zusammenfassung Es wird ein Satz über die Stützhyperebenen eines konvexen Funktionals in einem reellenBanach-Raum bewiesen. Dieser ist ein wesentliches Hilfsmittel zur Herleitung von Dualitätssätzen für nichtlineare Programme inBanach-Räumen.
Vorgel. v.:J. Nitsche. 相似文献
317.
318.
Dexuan Xie Suresh B. Singh Eugene M. Fluder Tamar Schlick 《Mathematical Programming》2003,95(1):161-185
The similarity and diversity sampling problems are two challenging optimization tasks that arise in the analysis of chemical
databases. As a first step to their solution, we propose an efficient projection/ refinement protocol based on the principal
component analysis (PCA) and the truncated-Newton minimization method implemented by our package TNPACK (PCA/TNPACK). We show
that PCA can provide the same initial guess as the singular value decomposition (SVD) for the optimization task of solving
the distance-geometry optimization problem if each column of a database matrix has a mean of zero. Hence, our PCA/TNPACK approach
is analogous to the SVD/TNPACK projection/refinement protocol that we developed recently for visualizing large chemical databases.
Using PCA/TNPACK and the Merck MDDR database (MDL Drug Data Report), we further investigate the projection/refinement procedure
with regards to the preservation of the original clusters of chemical compounds, the accuracy of similarity and diversity
sampling of chemical compounds, and the potential application in the study of structure activity relationships. We also explore
by simple experiments accuracy and efficiency aspects of the PCA/TNPACK procedure compared to those of a global optimization
algorithm (simulated annealing, as implemented by the program package SIMANN) in terms of producing the projection mapping
of a database. Numerical results show that the 2D PCA/TNPACK mapping can preserve the distance relationships of the original
database and is thus valuable as a first step in similarity and diversity applications. Of course, the generation of a global
rather than local minimizer and its interpretation in terms of pharameceutical applications remains a challenge. Since all
numerical tests are performed on the Merck MDDR database, results are representative of realistic cases encountered in the
field of drug design, and may help analyze properties of medicinal compounds.
Received: December 21, 2000 / Accepted: August 19, 2002 Published online: September 27, 2002
Mathematics Subject Classification (2000): 65K10, 62H25, 92C50 相似文献
319.
Petrin R.R. Kliewer M.L. Beasley J.T. Powell R.C. Aggarwal I.D. Ginther R.C. 《Quantum Electronics, IEEE Journal of》1991,27(4):1031-1038
The results of a study of the spectroscopic and laser properties of a Nd3+ doped fluoride glass are presented. Threshold energies and slope efficiencies are reported along with the stimulated emission cross section for the laser transition. The effect of excited state absorption of pump photons on the slope efficiency is investigated 相似文献
320.
In the design of a Computer Communication Network (CCN), the reliability between any pair of nodes and the maximum permissible installation cost are of great importance. These characteristics are largely dependant upon the topological layout of the links, their costs and reliabilities. Having the knowledge of the topological layout of the various computer centres (nodes) and maximum permissible cost of installing the various links at their pre-assigned positions; in this paper an algorithm for obtaining an optimal network topology which gives the maximum s?t reliability is presented. The developed method is general and is computerized. The proposed method has an additional advantage that the system is not to be redesigned, if at a later stage the permissible cost is enhanced by budgetary provisions. An example illustrates the algorithm. 相似文献