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101.
Intercellular communication between follicular angiotensin receptors and Xenopus laevis oocytes: medication by an inositol 1,4,5- trisphosphate-dependent mechanism 下载免费PDF全文
In Xenopus laevis oocytes, activation of angiotensin II (AII) receptors on the surrounding follicular cells sends a signal through gap junctions to elevate cytoplasmic calcium concentration ([Ca2+]i) within the oocyte. The two major candidates for signal transfer through gap junctions into the oocyte during AII receptor stimulation are Ins(1,4,5)P3 and Ca2+. In [3H]inositol-injected follicular oocytes, AII stimulated two- to fourfold increases in phosphoinositide hydrolysis and production of inositol phosphates. Injection of the glycosaminoglycan, heparin, which selectively blocks Ins(1,4,5)P3 receptors, prevented both AII-stimulated and Ins(1,4,5)P3-induced Ca2+ mobilization in Xenopus follicular oocytes but did not affect mobilization of Ca2+ by ionomycin or GTP. These results indicate that the AII-regulated process of gap junction communication between follicular cells and the oocyte operates through an Ins(1,4,5)P3-dependent mechanism rather than through transfer of Ca2+ into the ooplasm and subsequent Ca(2+)-induced Ca2+ release. 相似文献
102.
The β-carboxylic group in N-dialkylphosphorylated aspartic acid has an activating effect that gives rise to peptides, esters, and ester exchange at the phosphoryl group. In contrast, the γ-carboxylic group of N-alkylphosphorylated glutamic acid has a much smaller effect. Some of the self-activating products were isolated and many model compounds were synthesized to study the novel activating effect of the β-carboxylic group. Mixed anhydride intermediates derived from α-carboxylphosphoryl and β-carboxylphosphoryl groups are proposed for the self-activation mechanism. 相似文献
103.
Jiří Váňa 《Folia Geobotanica》1982,17(1):63-87
The present study deals with five genera of hepatics in Africa, Isotachis Mitt., Anastrophyllum (Spruce) Steph., Tritomaria Schiffn. ex Loeske, Gymnocoleopsis (Schust.) Schust. and Lophozia (Dum.) Dum. All African populations of the genus Isotachis Mitt. are considered to be one species, I. aubertii (Schwaegr.) Mitt. Four species of Anastrophyllum (Spruce) Steph. (s.l.), A. auritum (Lehm.) Steph., A. piligerum (Nees) Spruce, A. subcomplicatum (Lehm. et Lindenb.) Steph. and A. minutum (Schreb.) Schust., and two species of Tritomaria Schiffn. et Loeske, T. camerunensis S. Arnell and T. exsecta (Schrad.) Schiffn. ex Loeske occur in Africa. Gymmocoleopsis multiflora (Steph.) Schust. represents a genus and species hitherto unreported for the African flora. Finally, five Lophozia (Dum.) Dum. species, L. argentina (Steph.) Schust., L. capensis S. Arnell, L. decolorans (Limpr.) Steph., L. hedbergii S. Arnell and L. tristaniana (S. Arnell) Váňa, are reported from central and southern Africa; two of these (L. argentina (Steph.) Schust. and L. decolorans (Limpr.) Steph.) represent the first reports from Africa. 相似文献
104.
Dagmar Jičínská Eduard Brabec Marcel Rejmánek Jan Jeník Joří Haager Josef Holub Věroslav Samek Hana Rambousková Josef Holub Marie Naděžda Končalová Robert Neuhäusl Josev Kyncl František Krahuleo Jaroslav Dobrý Blanka Úlehlová Jiří Úlehla Eliška Rybníčková Kamil Rybníček 《Folia Geobotanica》1982,17(4):431-448
105.
106.
Jiří Dostálek 《Folia Geobotanica》1980,15(1):59-73
Pyrus spinosa Forsk. (=P. amygdaliformis Will.) kreuzt sich in beträchtlichem Masse mitP. pyraster Burgsd. und mitP. communis L. Es wurden drei Hybriden beschrieben, die zwar weniger, aber gut keimende Samen haben. Potentiell sind in der bulgarischen Population vonP. spinosa Merkmale aller infraspezifischen Taxa vertreten, doch nur zwei von ihnen kommen in grösserem Masse vor, das Vorkommen der weiteren drei ist nur gering. Merkmale des übrigen infraspezifischen Taxon kommen nur in Kombination mit Merkmalen anderer Taxa bei Übergangsformen vor. Vorläufig ist auch die Verbreitung vonP. spinosa und ihrer Hybriden in Bulgarien angegeben. 相似文献
107.
108.
109.
Jiřina Dvořáková 《Biologia Plantarum》1979,21(5):372-375
The capability of utilizing 20 amino acids and 2 amides as the sole nitrogen source for growth was studied in two green algae
(Chlorophyceae). A comparison was made of the growth rate of algae in a mineral nutrient solution containing nitrate as the nitrogen source,
with that in the same solution in which nitrogen in the form of nitrate was substituted by an equivalent nitrogen amount in
the form of various amino acids. In addition to this, another series of experiments was carried out in whioh both culture
media were supplied with glucose. The results show that both algae utilize a series of amino acids in dependence of their
structure (mostly 3-carbon amino acids). The growth rate ofChlorella in the presence of these sources is the same as in nitrate, that ofScenedesmus even much higher. In the cultures containing glucose both algal species exhibit a higher growth rate in the media with the
nitrate nitrogen source than in those with amino acids (with the exception of glycine inScenedesmus). 相似文献
110.
Barley seeds were treated for 3 h at 25°C with 240 mM ethyl methanesulphonate (EMS), washed for 18 h, treated with various concentrations of unbuffered sodium azide (pH 6.7–7.3) for 3 h at 25°C, re-dried to 30% water content and either sown immediately or stored at 25°C for 12 days and then sown. The synergistic action of sodium azide post-treatment has been demonstrated only for the EMS-induced M1 germination reduction, while the EMS-induced M1 sterility and the yield of M2 chlorophyll mutants were unaffected. The ?storage” recovery from EMS-induced mutagenic effects was insensitive to sodium azide post-treatment. The 12 day-seed storage at 25°C brought about an improvement of M1 germination, M1 survival, M1 fertility and a decrease in the amount of M2 mutants, regardless of whether sodium azide post-treatment was applied or not. 相似文献