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991.
992.
The reaction sequence 9→11→ 20→23 was carried out as model investigation for the total synthesis of 20-methyl-pregn-4-en-3-on (23) via 9 obtainable by cyclization of tetraen-ol 1. A-nor-steroid-3(5),8(14) diene 9 together with isomers 10–12 was prepared by HBr induced rearrangement of the cyclosteroids 6/7, obtained from ergosterin. 10 and 12 were isomerized on palladium charcoal to 9 or 11 respectively; 9 could be isomerized by HBr to 11. Regioselective hydrogenation of 11 yielded the mono-en 20 which was converted to 23. 相似文献
993.
Dipl.-Math. W. Wolf 《Mathematical Methods of Operations Research》1968,12(1):50-54
Zusammenfassung Mit Hilfe des Iterationsverfahrens vonHoward wird das optimale Anschaffungs-und Betriebsalter für ein deutsches PKW-Fabrikat bestimmt. Diese Zeiten liegen unterhalb der entsprechenden Werte, dieHoward auf Grund amerikanischer Daten erhalten hat.
Vorgel. v.: H.P.Künzi. 相似文献
Summary By aid of theHoward-Algorithm the optimal purchase- and operating age for a German automobile is determined. These time-spans are lying below the corresponding values which were received byHoward on account of American data.
Vorgel. v.: H.P.Künzi. 相似文献
994.
A theory of generalized statical bases is developed for usein the flexibility methods as applied to skeletal structuralproblems. It is shown that any maximal linearly independentset of cycles of the integral cycle group of a linear graphmodel of the structure may be used in the formation of a staticalbasis. Such a set of simple cycles is found by embedding thisgraph into a two-dimensional polyhedron. Cell complexes areformed so that the simple cycles bounding the 2-cells correspondto substructures on which a statical basis may be constructed.Two methods are given for the construction of the embeddings.In one a collapsible complex is formed from a union of a setof disks; while in the other the embedding is into an orientablemanifold which is modified to form an admissible complex. 相似文献
995.
Dipl.-Phys. H. J. Wolf Dr. P. Steiner Dr. E. Gerdau cand. phys. W. K. Müller cand. phys. U. Lewandowski Dr. A. Roggenbuck 《Zeitschrift für Physik A Hadrons and Nuclei》1970,232(3):256-267
Time differentialγγ-angular correlation measurements have been performed to determine the electric interaction of the 2.3 MeVI=5? state of120Sn in different polycristalline antimony compounds. A calibration of the field gradient was achieved by Mößbauerexperiments with the 23.8 keVI=3/2+ state in119Sn using identical sources. From the ratio of the measured electric interactions the ratio of the quadrupole moments is deduced as: $$\left| {\frac{{Q(2.3{\mathbf{ }}MeV level,{\mathbf{ }}I = 5^ - ,^{120} Sn)}}{{Q(2.8{\mathbf{ }}keV level,{\mathbf{ }}I = {3 \mathord{\left/ {\vphantom {3 2}} \right. \kern-\nulldelimiterspace} 2}^ + ,^{119} Sn)}}} \right| = 2.86(15)$$ . Using 0.06 (2) b for the quadrupole moment of the 23.8 keV level in119Sn one gets for the quadrupole moment of the 2.3 MeV level in120Sn ¦Q(2.3 MeV level,I=5?,120Sn)¦=0.021 (8) b. 相似文献
996.
Ohne ZusammenfassungSatz 4.1 und 4.6 der vorliegenden Arbeit entstammen der Dissertation des Verf. (Univ. Göttingen, Mai 1967). 相似文献
997.
Krohn S Lange M Grieser M Knoll L Kreckel H Levin J Repnow R Schwalm D Wester R Witte P Wolf A Zajfman D 《Physical review letters》2001,86(18):4005-4008
The dissociative recombination of LiH+ ions with low-energy electrons is observed at a storage ring and the final states are analyzed using fragment imaging and field ionization techniques. The rate coefficient is found to be larger than its estimated value used in astrophysical models. Mostly the highest energetically possible Rydberg states of the lithium atom are populated by the reaction, indicating a common trend for molecular recombination via the noncrossing mode. 相似文献
998.
A rigid C2-symmetric 1,8-diacridylnaphthalene N,N'-dioxide fluorosensor has been developed for enantioselective recognition of chiral hydrogen bond donors such as amines and amino acids. 相似文献
999.
Levy G Lutz I Krüger A von Tümpling W Kloas W 《Analytical and bioanalytical chemistry》2004,378(3):676-683
Endocrine-disrupting compounds (EDC) are predominantly investigated with respect to their ability to mimic or block estrogenic actions. However, it is well-known that EDC can act as agonists or antagonists of androgen- and estrogen-response systems. For that reason, there is an obvious need for bioassays providing the possibility of detecting (anti-)estrogenic and (anti-)androgenic effects. The retinol-binding protein (RBP) seems to be a useful molecular biomarker for assessing all modes of action of EDC, because it is regulated by sex steroid hormones. This study was conducted to establish RBP as a biomarker for determination of (anti-)estrogenic and (anti-)androgenic effects of EDC using a Xenopus laevis primary hepatocyte culture system. It could be shown that RBP mRNA expression in X. laevis hepatocytes was stimulated by estrogens in a dose-dependant manner whereas a combination of estrogen and androgen or estrogen and anti-estrogen treatment suppressed estrogenic stimulating effects. Androgens testosterone and dihydrotestosterone were able to reduce RBP mRNA expression and the anti-androgen vinclozolin could abolish the mRNA synthesis-suppressing activity of the androgen dihydrotestosterone. These results clearly demonstrated that RBP mRNA expression patterns in Xenopus laevis hepatocytes have different modes of (anti-)estrogenic and (anti-)androgenic action and can be used for examination of suspected EDC. Moreover, water samples from sewage-treatment plant effluents were applied to liver cells and expression levels of RBP and estrogen receptor mRNA (a known estrogenic biomarker) were detected. These samples had high estrogenicity but caused low to moderate induction of RBP mRNA synthesis, leading to the conclusion that RBP levels represent the sum of all possible effects (estrogenic and other effects) of EDC in environmental samples.Abbreviations EDC
Endocrine-disrupting compounds
- RBP
Retinol-binding protein
- STP
Sewage-treatment plants
- ER
Estrogen receptor
- AR
Androgen receptor
- E2
17-Estradiol
- EE
Ethynylestradiol
- T
Testosterone
- DHT
Dihydrotestosterone
- MT
Methyltestosterone
- TAM
Tamoxifen
- VC
Vinclozolin
- CMF
Calcium-magnesium free
- ME
Minimal essential 相似文献
1000.
The In DX center and the DX-like configuration of the Cd host atom in CdTe are investigated using density functional theory. The simultaneous calculation of the atomic structure and the electric field gradient (EFG) allows one to correlate the theoretically predicted structure of the DX center with an experimental observable, namely, the EFG obtained from radioactive 111In/111Cd probe atoms in In doped CdTe. In this way, the experimental identification of the DX center structure is established. 相似文献