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101.
Two diterpene carboxylic acids, one a new kaurenoid derivative and one the previously characterized labdane, ()-cis-ozic acid, as well as a 相似文献
102.
Paula Klevjer-Anderson Gertrude Case Buehring 《In vitro cellular & developmental biology. Plant》1980,16(6):491-501
Summary The individual effects of seven hormones on the in vitro growth rate of different classifications of human mammary epithelium
were compared. Hormones used were: 17β-estradiol, estriol, progesterone, hydrocortisone, testosterone, prolactin, and growth
hormone. Cell cultures included three established breast cell lines and primary monolayer cultures established form breast
fluids and excised mammary tissue from 40 women and 4 men. Specimens comprised three classifications: normal, nonmalignant
atypical, and malignant. Growth was quantitated in situ and expressed as population doubling time. Principal findings were:
(a) estrogens, prolactin, and growth hormone stimulated growth of normal cells more frequently than growth of malignant cells,
whereas testosterone and hydrocortisone stimulated growth of malignant cells more frequently than growth of normal cells;
(b) cells cultured from nonmalignant atypias generally showed hormone response profiles intermediate between those of normal
and malignant cells; (c) progesterone stimulated the growth of cells from malignant specimens but not the growth of cells
from normal and nonmalignant atypical samples.
This research was supported by NIAID Research Training Grant 5-TO1-A1-00332-06. 相似文献
103.
The relative contributions of ventral blood island mesoderm and dorsal anterior mesoderm to differentiated lineages of hematopoietic cells was assessed by reciprocal grafting of cytogenetically labeled tissues between 67- and 72-hr-old frog embryos (Shumway stages 15–16). Diploid (2N) and triploid (3N) cell populations from hematopoietic organs were distinguished by Feulgen-DNA microdensitometric analysis. Ventral blood island mesoderm appears to contribute an embryonic erythrocyte population that progressively declines during larval development. Dorsal anterior mesoderm appears to contribute a population of precursor cells that gives rise to differentiated lineages of hematopoietic cells found in the thymus, pronephros, mesonephros, spleen, and blood. Histological examination of the developing dorsal anterior area indicates that extensive vascularization is a prominent characteristic of this region. The dorsal aortae and vasculature surrounding the pronephros may be sites where at least one population of hematopoietic cells matures and subsequently enters circulation. 相似文献
104.
Paula Branefors-Helander Björn Classon Lennart Kenne Bengt Lindberg 《Carbohydrate research》1979,76(1):197-202
The structure of the capsular antigen from Haemophilus influenza type c has been investigated, n.m.r. spectroscopy being the principal method used. It is concluded that the antigen is composed of repeating-units having the following structure: O-Acetyl groups are present in ~90% of the repeating-units. 相似文献
105.
1. Ferricytochrome c3 from D. gigas exhibits two low-spin ferric heme EPR resonances with gz-values at 2.959 and 2.853. Ferrocytochrome c3 is diamagnetic based on the absence of any EPR signals. 2. EPR potentiometric titrations result in the resolution of the two low-spin ferric heme resonances into two additional heme components representing in total the four hemes of the cytochrome, with EM values of -235 mV and -315 mV at heme resonance I and EM values of -235 mV and -306 mV at heme resonance II. 3. EPR spectroscopy has detected a significant diminution of intensity (approx. 60 p. 100) in the gx amplitude of ferricytochrome c3 in the presence of D. gigas ferredoxin II. The presence of ferredoxin II also causes a more negative shift in the EM of the second components of the signals at heme resonances I and II of cytochrome C3. Both observations suggest that an interaction has occurred between cytochrome C3 and ferredoxin II. 4. The results presented suggest that the heme ligand environment of ferricytochrome c3 from D. gigas is less perturbed and/or less asymmetric than environment for ferricytochrome c3 from D. vulgaris whose EPR behavior indicates the non-equivalence of all four hemes. 相似文献
106.
107.
108.
109.
Mireille Bruschi E.Claude Hatchikian Jean Le Gall JoséJ.G. Moura António V. Xavier 《BBA》1976,449(2):275-284
Three forms of ferredoxin FdI, FdI′, and FdII have been isolated from Desulfovibrio gigas, a sulfate reducer. They are separated by a combination of DEAE-cellulose and gel filtration chromatographic procedures. FdI and FdI′ present a slight difference in isoelectric point which enables the separation of the two forms over DEAE-cellulose, while FdII is easily separated from the two other forms by gel filtration. The three forms have the same amino acid composition and are isolated in different aggregation states. Molecular weight determinations by gel filtration gave values of 18 000 for FdI and FdI′ and 24 000 for FdII, whereas a value of 6000 is determined when dissociation is accomplished with sodium dodecyl sulfate. The electronic spectra are different and their ultraviolet-visible absorbance rations are 0.77, 0.87 and 0.68 respectively for FdI, FdI′ and FdII. Despite these differences, the physiological activities of the three forms are similar as far as the reduction of sulfite by molecular hydrogen is concerned. 相似文献
110.
Paula M. Pitha Vitolis E. Vengris Fred H. Reynolds 《Journal of cellular biochemistry》1976,4(4):467-473
The mechanism of interferon action in human fibroblasts has been studied by use of both antisera to human fibroblast interferon and the antisera to the surface of human fibroblast cell. The anti-interferon serum completely neutralized the antiviral effect of human fibroblast interferon. Interferon antiserum prevented the intracellular antiviral state from developing when added to the medium of the cells in which interferon synthesis had already been induced by poly (I · C). This suggests that development of the antiviral state involves interferon interaction with the external part of the producing cell. Treatment with the serum directed against the surface of human fibroblast cells failed to inhibit the antiviral activity of human interferon in these cells. In addition, the effect of gangliosides on the antiviral activity of human interferon was studied and it was found that human interferon binds to gangliosides and that this interaction leads to inactivation of the antiviral effect of interferon. Pretreatment of human fibroblasts with gangliosides had no effect on the sensitivity of these cells to exogenous interferon. 相似文献