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41.
Christoph Theurer Hans-Joachim Treumann Thomas Faust Ursula May Wolfgang Kreis 《Plant Cell, Tissue and Organ Culture》1994,38(2-3):327-335
The glycosylation and deglycosylation of cardiac glycosides was investigated using cell suspension cultures and shoot cultures, both established from Digitalis lanata EHRH. plants, as well as isolated enzymes. Shoots were capable of glucosylating digitoxigenin, evatromonoside, digiproside, glucodigitoxigenin and digitoxin. Suspension cultured Digitalis cells glucosylated all the substrates mentioned but digiproside, whereas the UDP-glucosedependent cardinolide glucosyltransferase isolated from that source did not accept digitoxigenin and digiproside as substrates. It is concluded that at least three different glucosyltransferases are involved in cardiac glycoside formation in Digitalis. Similar experiments carried out with glucosylated cardenolides which were administered to cultured cells, shoots and a cardenolide -glucosidase isolated from young leaves revealed that at least two different glucosidases occur in Digitalis lanata, albeit in different tissues or during different phases of development. The biotransformation of glucoevatromonoside was investigated using unlabelled compound and [14C-glucose]-glucoevatromonoside synthesized enzymatically. After 7 d of incubation almost no radioactivity could be recovered from the cardenolide fraction, indicating that the terminal glucose of glucoevatromonoside was now incorporated into volatile, hydrophilic and insoluble compounds. Since, on the other hand, large amounts of cardenolides were found in the experiments with unlabelled glucoevatromonoside it is assumed that steady state or pool size regulation is achieved by the coordinated action of a cardenolide glucosidase and a glucosyltransferase.Abbreviations Acdox
D-acetyldigitoxose
- dgen
digoxigenin
- dox
D-digitoxose
- dten
digitoxigenin
- dtl
D-digitalose
- fuc
D-fucose
- gten
gitoxigenin
- qun
D-quinovose
- CGH
cardenolide 16-O-glucohydrolase
- DFT
UDP-fucose:digitoxigenin 3-O-fucosyltransferase
- DGT
UDP-glucose:Digitoxin 16-O-glucosyltransferase
- DQT
UDP-quinovose:digitoxigenin 3-O-quinovosyltransferase 相似文献
42.
Ursula Kües Anna M. Tymon Wendy V. J. Richardson Georgiana May Paul T. Gieser Lorna A. Casselton 《Molecular & general genetics : MGG》1994,245(1):45-52
We have identified the seven genes that constitute the A43 mating-type factor of Coprinus cinereus and compare the organisation of A43 with the previously characterised A42 factor. In both, the genes that trigger clamp cell development, the so-called specificity genes, are separated into and loci by 7 kb of noncoding sequence and are flanked by homologous genes -fg and -fg. The specificity genes are known to encode two classes of dissimilar homeodomain (HD1 and HD2) proteins and have different allelic forms which show little or no cross-hybridisation. By partial sequencing we identified a divergently transcribed HD1 (a1-2) and HD2 (a2-2) gene in the A43 locus. a2-2 failed to elicit clamp cell development in three different hosts, suggesting that it is non-functional. a1-2 elicited clamp cells in an A42 host that has only an HD2 gene (a2-1) in its locus, thus demonstrating that the compatible A mating interaction is between an HD1 and an HD2 protein. The A43 locus contains three specificity genes, the divergently transcribed HD1 and HD2 genes b1-2 and b2-2 and a third HD1 gene (d1-1) that was shown by hybridisation and transformation analyses to be functionally equivalent to d1-1 in A42. An untranscribed footprint of a third A42 HD1 gene, c1-1, was detected between the A43 b2-2 and d1-1 genes by Southern hybridisation. 相似文献
43.
In Lake Constance, after several decades of cutrophication, a decrease in phosphorus loading over the last decade has lead to a partial recovery from eutrophication. Here we analyse the shift in the taxonomic composition of phytoplankton during the first decade of oligotrophication in Lake Constance. During the 1980s, spring total P concentrations decreased from ca. 130 to less than 50 ·l–1. This decrease was reflected by an approximately proportional decrease in summer phytoplankton biomass while spring phytoplankton biomass seemed unresponsive. Major taxonomic changes occured during both growth seasons. In spring, the proportion of diatoms, green algae and Chrysophyta increased while the proportion of Cryptophyta decreased. The summer trend was very different: the relative importance of diatoms decreased and Cryptophyta and Chrysophyta increased, while Chlorophyta reached their peak around 1985. These trends are also analysed at the genus level. Comparison with taxonomic trends during the eutrophication period shows the expected reversals in most cases. Comparison with other lakes shows general similarities, with the notable exception that Planktothrix rubescens has never been important in Lake Constance. The increase of diatoms during spring is attributed to their improved competitive performance with increasing Si:P ratios. Their decrease during summer is explained by the increasing silicate removal from the epilimnion by increasing spring populations. 相似文献
44.
Dipl. Geol. Jens Hefter Dipl. Geol. Volker Thiel Dr. Angela Jenisch Dr. Ursula Galling Dr. Stephan Kempe Dr. habil. Walter Michaelis 《Facies》1993,29(1):93-105
Summary Biomarker investigations were applied to the hydrocarbon fractions of three Recent (cyanobacterial mat, Lake Van microbialite
and Lake Satonda microbialite) and two Late Jurassic carbonate samples obtained from sponge bioherms. The relative concentrations
ofn-alkanes, monomethyl alkanes, acyclic isoprenoids, steroids and hopanoids in these samples are studied and their probable
biological precursors are discussed. Normal alkanes with carbon chain lengths ranging from C15 to C34 and monomethyl alkanes ranging from C17 to C21 with a varying methyl branching pattern are found. The major hydrocarbons are low molecular weight (LMW)n-alkanes (C15–C21) with a slight to strong predominance ofn-heptadecane (C17). High molecular weight (HMW)n-alkanes occur in low to moderate relative concentrations showing a preference of odd-carbon numbered compounds with a maximum
at C29. Within the acyclic isoprenoids, pristane, phytane/phytene, pentamethyl-eicosane, squalane and lycopane could be identified.
Polycyclic terpenoids of the sterane and/or hopane type are present in all carbonate samples. The carbon numbers of these
components range from 27 to 29 and 27 to 32, respectively. These organic compounds identified can be attributed to various
source organisms such as cyanobacteria, archaebacteria, algae and vascular plants. All hydrocarbon fractions of the samples
are characterized by moderate to high relative concentrations of compounds derived from cyanobacteria, signifying the role
of these organisms as contributors to the Recent as well as to the Late Jurassic carbonate deposits. 相似文献
45.
Ilias Tirodimos Inge-M. Pretorius-Güth Ursula Priefer Athanasios Tsaftaris Asterios S. Tsiftsoglou 《Applied microbiology and biotechnology》1993,38(4):526-530
In order to assess the risk associated with the deliberate release of genetically engineered microorganisms (GEMs) into the agricultural environment, the transfer of plasmids between bacterial strains was investigated under laboratory conditions. Genetically modified Rhizobium leguminosarum and Agrobacterium tumefaciens strains carrying the gentamycin acetyltransferase resistance gene (aacC1) on various plasmids were investigated for their ability to transfer the aacC1 gene to their wild-type (w.t.) counterparts, as well as to Pseudomonas syringae. Conjugation experiments between the various strains, were carried out after the relevant characteristics and conditions for selective growth of each bacterial strain had been ascertained. After conjugations on filters had been completed, the putative transconjugants were grown in media containing antibiotics and assessed for the presence of aacC1 gene by: (a) DNA plasmid profile; (b) expression of AAC(3)-I enzyme activity; (c) colony hybridization using a 32P-labelled DNA probe complementary to the aacC1 gene. The results obtained indicate that transfer of the aacC1 gene from genetically modified strains of R. leguminosarum into a plasmid-free strain of A. tumefaciens occurred via self-transmissible plasmids. Alternatively, genetically modified A. tumefaciens bearing the aacC1 gene on plasmids acquired from R. leguminosarum strains, transferred it ineffectively to a hardly detectable frequency. No transfer of the aacC1 gene from genetically modified R. leguminosarum or A. tumefaciens strains into P. syringae has been observed. These data indicate that in the absence of the RP4 element, genetically modified A. tumefaciens is not able to efficiently transfer aacC1 into w.t. R. leguminosarum and P. syringae.
Correspondence to: A. S. Tsiftsoglou 相似文献
46.
47.
Michael P. Challen Timothy J. Elliott Ursula Kües Lorna A. Casselton 《Molecular genetics and genomics : MGG》1993,241(3-4):474-478
The A mating factor of Coprinus cinereus determines compatibility in mating by regulating part of a developmental sequence that leads to dikaryon formation. The A genes that trigger development encode two different classes of homeodomain proteins, and for a successful mating, a protein of one class, HD 1, must interact with a protein of the other class, HD 2. In this report we show that C. cinereus A genes that encode HD 2 proteins, a2-1 and b2-1, can elicit A-regulated development in the heterologous host C. bilanatus. Transformation rates were very low, suggesting that the genes were poorly transcribed. The fact that the HD 2 genes are functionally expressed implies successful heteromultimeric association of putative DNA-binding proteins coded by the two Coprinus species. This interaction was sufficient to satisfy the need for different A factors in the formation of a fertile C. bilanatus dikaryon, but fertile dikaryons were more readily produced in matings with the a2-1 gene transformants. The C. cinereus A genes, b1-1 and d1-1, which encode HD1 proteins, were either not expressed or their proteins were non-functional in C. bilanatus. These experiments raise some interesting questions regarding HD1–HD2 protein interactions. 相似文献
48.
Fenge Christel Klein Cornelia Heuer Carsten Siegel Ursula Fraune Elisabeth 《Cytotechnology》1993,11(3):233-244
For an optimized bioreactor design which is adapted to the cultivation of sensitive animal cells different modular bioreactor components for gentle agitation, sufficient aeration and long-term perfusion were developed and investigated with respect to their suitability from laboratory to production scale. Aeration systems have been designed for both shear sensitive cells and cells which tolerate bubbles. The systems are based on either membranes for bubble-free aeration or stainless steel sparger systems. They were characterized by determination of their oxygen transfer capacity and optimized in cultivation processes of different cell lines under process conditions such as batch and perfusion mode.Different impellers for suspension cells and cells grown on carriers were investigated for their suitability to ensure homogeneous gentle mixing. A large pitch blade impeller as well as a novel 3-blade segment impeller are appropriate for homogeneous mixing at low shear rates. Especially with the 3-blade segment impeller fluid mechanical stress can be reduced at a given stirrer speed which is advantageous for the cultivation of cells attached to microcarriers or extremely shear sensitive suspension cells. However, our results indicate that shear sensitivity of animal cells has been generally overestimated.Continuous perfusion of both suspension cell cultures and cells cultivated on microcarriers could be successfully performed over extended periods of time using stainless steel spinfilters with appropriate pore sizes and systems based on microporous hydrophilic membranes. Spinfilters are suitable cell retention systems for technical scale bioreactors allowing continuous perfusion cultures of suspension cells (pore size 10 to 20 m) as well as anchorage dependent cells grown on microcarriers (pore size 75 m) over six weeks to 3 months.Applying the developed modules for agitation, aeration and perfusion process adapted bioreactor set-ups can be realized which ensure optimum growth and product formation conditions in order to maximize cell and product yields. 相似文献
49.
Gustav Kramer und Ursula von St. Paul 《Journal of Ornithology》1956,97(4):353-370
Zusammenfassung Schon veröffentlichte Feststellungen über verringertes Heimfindevermögen von Brieftauben im Winter werden bestätigt.Durch wiederholte Auflassungen über die gleiche Kurzstrecke (von NNW 22 km nach SSO) wird gezeigt, daß die Einzeltaube regelmäßig wesentlich schlechter abschneidet, wenn sie die gleiche, im Sommer durchflogene Strecke im Winter wiederholt. Durch Verwendung einer hinreichenden Anzahl von Erstfliegern in beiden Jahreszeiten wird der Wintereffekt auch durch Vergleich von Heimkehrschnelligkeiten verschiedener Individuen sichergestellt.Es wird gezeigt, daß die Verwandlung des Landschaftsbildes nicht die Ursache des winterlichen Versagens sein kann. Es ist auch unwahrscheinlich, daß die im Winter geringere Höhe des Sonnenstandes schuld ist. Entgegen einer früher vonKramer geäußerten Meinung können auch weder niedrige Temperaturen als solche noch direkt mit ihnen streng gekoppelte Faktoren verantwortlich gemacht werden.Der Einwand, daß es sich beim Wintereffekt nicht um eine Orientierungsbehinderung, sondern um eine jahreszeitlich, vielleicht mit der Taglänge korrelierte Schwächung des Heimkehrimpulses handeln möge, wird kritisch besprochen. Gegen diesen Einwand wird geltend gemacht, daß nach den bisherigen Erfahrungen der März noch zu den Winter-Monaten zählt; sogar ein Aprilflug trug intermediäre Züge. Dagegen funktioniert das Heimkehrvermögen im September noch gut. — Eine Korrelation mit der Intensität des Fortpflanzungsverhaltens kann deswegen nicht vorliegen, weil die Fortpflanzungsaktivität schon im Februar erheblich gesteigert ist. Es wird der Nachweis geführt, daß bei gleichen Temperaturen im Winter signifikant verschiedene Heimkehrerfolge an nahe beisammenliegenden Daten (3. 1. und 26. 1. 1956) erzielt werden können.Auch für andere Strecken (36 km S — N, 41 km O — W, 94 km S — N) werden Vergleiche von Heimflügen im Sommer mit solchen im Winter angestellt. Die Winterergebnisse sind durchweg erheblich schlechter.Das Bestehen des Wintereffekts zeigt, daß die Orientierung bei der Heimkehr auch über kurze Strecken nicht auf dem visuellen Erkennen von Landschaftsstrukturen beruht. Der Orientierungsmechanismus ist vielmehr unbekannt. Es ist vorläufig zu vermuten, daß er identisch ist mit dem, der über weitere Distanzen wirksam ist.Mit Unterstützung der Deutschen Forschungsgemeinschaft, welche das Fahrzeug zur Verfügung stellte und die Betriebsmittel dafür trug. 相似文献
50.
Walter K. F. Seelentag Ursula Günthert Parvin Saremaslani Eva Futo Madeleine Pfaltz Philipp U. Heitz Jürgen Roth 《Histochemistry and cell biology》1996,106(3):283-289
CD44 isoforms have been implicated in tumor progression and metastasis formation. This study presents a thorough immunohistochemical
analysis of CD44 standard and isoform expression in normal human skin appendages and epidermis applying monoclonal antibodies
against CD44s, CD44v3, -v4, -v5, -v6, and -v9. An improved immunohistochemical protocol with microwave-based antigen retrieval
in paraffin sections and heavy metal amplification of the diaminobenzidine reaction product provided enhanced resolution and
sensitivity as compared to studies on frozen sections. The hair follicle, the seborrheic and eccrine sweat glands were strongly
positive for all CD44 isoforms studied. In the latter, the clear cells but not the dark (intercalated) cells were positive.
The sudoriferous ducts adjacent to the glands were weakly positive for all CD44 isoforms and strongly positive near the skin
surface. In the apocrine glands, the basal cells showed only a moderate positivity. The myoepithelial cells expressed only
CD44s. In the epidermis, all CD44 isoforms were detectable, with strongest CD44 immunostaining in the lower third of the stratum
spinosum and weaker staining in the stratum basale and the upper two-thirds of the stratum granulosum. The stratum granulosum
and corneum were unreactive. Thus, a regional and cell type-specific CD44 expression was revealed.
Accepted: 10 May 1996 相似文献