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141.
The marine opisthobranch molluscAplysia punctata was cultured at the Laboratoire de Biologie Marine in Concarneau, France.A. punctata veligers settled and underwent metamorphosis on the algaLomentaria articulata, but not onUlva spp., Palmaria marina, Laminaria spp. andFucus spp.Research supported by grants from The Arts Foundation and the Lerner Fund for Marine Research of the American Museum of Natural History. We wish to thank Director Yves Legal, College de France for his support and cooperation. 相似文献
142.
Epimastigote forms of Trypanosoma theileri were grown at 25°C in insect cell culture media and in Glossina tissue cultures for more than 6 months. Doubling times of 10–14 h during exponential growth were observed. In cell cultures which had been derived from pupal tsetse flies growth rates were higher than in cell free media; in a larval cell line, however, growth of T. theileri was inhibited. Ecdysteroids and juvenile hormone I reduced multiplication of T. theileri in cell free media. When T. theileri was incubated in different sera only fetal calf serum (FCS) supported growth. Epimastigote forms transformed into trypomastigote bloodforms when cultured at 37°C in FCS, vertebrate cell cultures, and Eagle's medium, but not in insect media or Glossina cell cultures. Oxygen uptake of epimastigotes could be inhibited by rotenone antimycin A and cyanide; trypomastigotes were not affected by these inhibitors. 相似文献
143.
T-tubes in cultured mammalian myocardial cells 总被引:2,自引:0,他引:2
Summary T-tubes are among the last structural elements of the mammalian myocyte to develop in vivo. We were able to identify T-tubes in early cultures of neonatal rat myocytes. Ventricles were excised from 3- to 4-day-old neonatal rats, incubated overnight in cold trypsin, and treated with sequential changes of collagenase-hyaluronidase. Fractions of cells isolated in this manner were pooled and cultured in plastic petri dishes. In cells prepared for transmission electron microscopy, T-tubes were observed at the cell periphery of cultured myocytes, but were more difficult to identify as the cultures aged and became overgrown by fibroblasts. T-tubes were identified by virtue of their continuity with the sarcolemma, their relatively large diameter, and their regular entry at the level of the Z line. Even at optimal culture ages, T-tubes were not present in every myocyte. At the times T-tubes could be located, myocytes were beating and had begun to establish intercalated discs and gap junctions. The de novo formation of T-tubes in cultured myocytes of neonatal rat heart reflects a duplication of in vivo differentiation by the cultured myocyte. The appropriateness of cultured myocytes in the study of the development and physiology of the heart is emphasized by the in vitro formation of T-tubes.Supported by research grants from the Muscular Dystrophy Association, Inc., The Schlieder Foundation, and USPH-Training Grant HL 07098-04. The authors are indebted to Philip Constantin for assistance in dissociating and culturing heart tissue. 相似文献
144.
Paracoccus denitrificans was grown aerobically during two-(carbon)substrate-limitation on mannitol and methanol in chemostat cultures. Theoretical growth parameters were calculated based on the presence of 2 or 3 sites in the electron-transport chain of Paracoccus denitrificans. Experimental growth parameters determined during two-(carbon)substrate growth were conform to the presence of 3 sites of oxidative phosphorylation, while cells grown only on mannitol possessed 2 sites. The maximum growth yield on adenosine triphosphate (ATP), corrected for maintenance requirements, determined in chemostat experiments in which the methanol concentration is less than 2.11 times the mannitol concentration was 8.6 g of biomass. When the methanol concentration was more than 2.11 times the mannitol concentration the maximum growth yield on adenosine triphosphate decreased due to the more energy consuming process of CO2-assimilation. Cells use methanol only as energy source to increase the amount of mannitol used for assimilation purposes. When the methanol concentration in chemostat experiments was more than 2.11 times the mannitol concentration, all mannitol was used for assimilation and excess energy derived from methanol was used for CO2-assimilation via the ribulose-bisphosphate cycle. The synthesis of ribulosebisphosphate carboxylase was repressed when the methanol concentration in chemostat experiments was less than 2.11 times the mannitol concentration or when Paracoccus denitrificans was grown in batch culture on both methanol and mannitol. When in chemostat experiments the methanol concentration was more than 2.11 times the mannitol concentration ribulose-bisphosphate carboxylase activity could be demonstrated and CO2-assimilation will occur. It is proposed that energy produced in excess activates or derepresses the synthesis of the necessary enzymes of the ribulose-bisphosphate cycle in Paracoccus denitrificans. Consequently growth on any substrate will be carbonas well as energy-limited. When methanol is present in the nutrient cells of Paracoccus denitrificans synthesize a CO-binding type of cytochrome c, which is essential for methanol oxidase activity.The reason for the increase in efficiency of oxidative phosphorylation from 2 to 3 sites is most probably the occurrence of this CO-binding type of cytochrome c in which presence electrons preferentially pass through the a-type cytochrome region of the electron-transport chain.Non Standard Abbreviations X
prosthetic group of methanol dehydrogenase
-
q
substrate
specific rate of consumption of substrate (mol/g biomass. h.)
-
Y
substrate, Y
substrate
MAX
are respectively the growth yield and the maximum growth yield corrected for maintenance requirements (g biomass/mol)
-
m
substrate
maintenance requirement (mol substrate/g biomass)
-
specific growth rate (h-1)
-
M
[methanol]/[mannitol] ratio in the nutrient
- N
part of mannitol that is assimilated when M=o
-
R
m
amount of methanol-equivalents that has the same energy content as 1 mannitol-equivalent
-
P/O
N
, P/O
F
, P/O
X
is the amount of ATP produced during electron-transport of two electrons from respectively NADH+H+, FADH2 and XH2 to oxygen 相似文献
145.
Bernhard H. J. Juurlink Sergey Fedoroff 《In vitro cellular & developmental biology. Plant》1979,15(2):86-94
Summary Whole mouse embryos were grown in vitro from Theiler stage 12 (1 to 7 somites) to Theiler stages 15 and 16 (25 to 35 somites).
This procedure gives experimental access to precisely staged embryos during the early period of neurogenesis. To follow the
further development of neurons in vitro, fragments of spinal primordia were set up from these cultured embryos. In such cultures,
the proliferation of precursor cells, the formation of postmitotic cells and, finally, the cytodifferentiation of neurons
were observed.
A preliminary account of this work was given at the Tissue Culture Association Meeting in 1977, and the Canadian Federation
of Biological Societies Meeting in 1977 (1,2).
This work was supported by Grant MT 4235 from the Medical Research Council of Canada. 相似文献
146.
WILLIAM TRAGER 《The Journal of eukaryotic microbiology》1979,26(1):125-129
SYNOPSIS. A new design of flow vessel provides a method for continuous culture of P. falciparum in a settled layer of human erythrocytes with a slow flow of culture medium over them. The parasitemia is kept fluctuating from ? 1%, just after addition of fresh erythrocytes. to ? 10%, 2 or 3 days later. Each vessel provides each week 3 harvests, each containing ? 0.6–1 × 109 parasites. 相似文献
147.
Lucy A. Barrett Wolfgang J. Mergner Benjamin F. Trump 《In vitro cellular & developmental biology. Plant》1979,15(12):957-966
Summary Segments of human thoracic aorta were maintained in long-term explant culture for 18 weeks in serum-supplemented medium. The
aortas were grossly normal in appearance, and random samples fixed for light microscopy prior to culture revealed a normal
morphology. The intima contained no more than five layers of smooth muscle cells. After 7 days in culture, the intima was
noticeably thicker than the uncultured segments. The increased thickness was due to proliferating smooth muscle cells and
production of extracellular material. After several months in culture, extracellular material consisting of collagen and flocculent
material was present in areas resembling atherosclerotic fibrous plaques. A peripheral growth, which formed around the explant,
was composed of fibroblastlike cells and added to the overall thickness of the intima. However, aortic segment maintained
for up to 2 months in serum-free culture medium showed no cellular proliferation. This study demonstrates that changes resembling
early stages of atherosclerosis occur in human aortas maintained in explant culture using routine culture procedures.
Supported in part by the Pangborn Fund and the Graduate School of the University of Maryland.
This is publication 443 from the Cellular Pathobiology Laboratory. 相似文献
148.
Molecular changes in cell surface membranes resulting from trypsinization of sarcoma 180 tumor cells
John W. Huggins Robert W. Chestnut Norman N. Durham Kermit L. Carraway 《生物化学与生物物理学报:生物膜》1976,426(4):630-637
Sarcoma-180 tumor cells in culture or grown as an ascites form in the CD-1 mouse have been subjected to mild trypsinization procedures in order to study morphological and molecular changes resulting from proteolysis. The cells attached to a substratum become rounded within 20 min and most undergo cell division, but they do not detach from the substratum. Removal of trypsin permits the cells to go back to their original spindle shape over an 8–20 h period.Surface membranes were isolated from trypsinized ascites and cultured cells and subjected to dodecyl sulfate-acrylamide gel electrophoresis. Both cell types showed the same two kinds of changes in electrophoretic patterns. First, there was a loss of glycoproteins from both cell types, even though they show different complements of cell surface glycoproteins. Second, there is a loss of high molecular weight polypeptides, which have previously been suggested to play a role in membrane stabilization and cell shape. These results further implicate these polypeptides in the control of cell morphology and offer circumstantial evidence for transmembrane interactions of surface glycoproteins with the high molecular weight polypeptides as a factor in controlling cell morphology. 相似文献
149.
Brian A. Laishes Gary M. Williams 《In vitro cellular & developmental biology. Plant》1976,12(7):521-532
Summary The conditions for obtaining representative, primary adult rat hepatocyte cultures were explored. The methods applied included
enzymatic liver perfusion which was nondestructive to hepatocytes, the prevention of aggregation of dissociated cells and
the selective attachment of viable cells. These procedures yielded a recovery of 50% of the liver cells which gave rise to
cultures representing 14% of the total liver cells. The cultures were composed of homogeneous epithelial-like cells cytologically
similar to hepatocytes and possessed a number of liver-specific enzymes. There was virtually no cell division initially and
most cells died between 24 and 48 hr. Insulin enhanced the attachment of the liver cells, altered their morphology, but did
not prolong cell survival.
This study was supported by grant no. BC 133 from the American Cancer Society. 相似文献
150.
Ross H. Hall 《In vitro cellular & developmental biology. Plant》1976,12(3):216-224
Summary Cells possess extraordinary powers to organize their molecular processes not only to maintain a cell in a given steady state
but also to recognize that state during differentiation. Regulation of these organizational forces appears to be under the
control of chemical factors, and a hormonal concept of regulation has evolved. Hormones have been considered to act by reacting
with a specific target site. This may be part of their mode of action, but I would like to suggest that a hormone enters and
becomes part of a total molecular resonance system. In so doing, the entire molecular system of the cell is modified.
Of the known plant hormones, the cytokinins, because of their role in experimentally induced cell division and differentiation,
serve as a probe of hormonal involvement in differentiation. Cultured somatic cells of tobacco plants can be induced to undergo
differentiation by addition of cytokinin and auxin to the medium. Studies of the cytokinin hormones show a series of diverse
molecular involvements. The archetype cytokinin, N6-(Δ2-isopentenyl) adenosine (i6Ado), occurs in some molecular species of tRNA where it plays a vital role in the codon-anticodon interaction of tRNA and
m-RNA. i6Ado under-goes extensive metabolism in the tobacco tissue. It is either degraded to adenosine or converted to derivatives
that possess biological activity. It is perhaps, therefore, more correct to consider the hormone function as being derived
from this total metabolic web.
The normal somatic cells of tobacco cultures spontaneously change occasionally into an autonomous form that requires no external
growth factors. This line of cells synthesizes i6Ado. The metabolic web of the hormone-dependent strain can be perturbed by added auxin but such is not the case in the autonomous
strain. These data provide some insight into the altered state of cytokinin activity in which a cell line changes into an
autonomous form. Curiously, in become independent of the requirement for exogenous cytokinin, the autonomous tissue becomes
sensitive to added cytokinin. i6Ado also inhibits the growth of lines of mammalian cancer cells grown in culture.
Presented in the formal symposium on Information Transfer in Eukaryotic Cells, at the 26th Annual Meeting of the Tissue Culture
Association, Montreal, Quebec, June 2–5, 1975. 相似文献