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61.
Expression of Bcl-2 protein in the epiphyseal plate cartilage and trabecular bone of growing rats 总被引:2,自引:0,他引:2
Ying Wang Renée Toury Michelle Hauchecorne N. Balmain 《Histochemistry and cell biology》1997,108(1):45-55
The protooncogene protein, Bcl-2, protects cells from apoptosis and ensures their survival in vitro by inhibiting the action
of the apoptosis-inducer, Bax. Its expression in proliferative and long-lived cells in vivo also indicates that it protects
against cell death. The chondrocytes of the epiphyseal plate cartilage undergo a series of maturation steps and deposit mineral
in the cartilage matrix before dying. The possibility that Bcl-2 helps protect chondrocytes until mineral deposition is completed
was investigated by determining the distribution of Bcl-2 immunoreactivity in the epiphyseal plate cartilage of growing rats
and its subcellular localization, using a specific antibody. The involvement of Bax in the triggering of chondrocyte death
was checked by immunocytochemistry. Bcl-2 expression in the osteoblasts and the final result of their evolution, the osteocytes,
was also examined in trabecular bone. Bcl-2 immunoreactivity was non-uniformly distributed throughout the epiphyseal cartilage.
It was maximal in proliferative chondrocytes, decreased in mature chondrocytes, and low in hypertrophic chondrocytes, whereas
there was Bax immunoreactivity in all chondrocytes examined. Immunolabeling was intense in osteoblasts but considerably lower
in fully differentiated osteocytes. Bcl-2 immunoreactivity was mainly in the cytoplasm of chondrocytes, osteoblasts, and early
osteocytes; the nuclei appeared clear. The subcellular distribution of Bcl-2 immunolabeling in chondrocytes, revealed by gold
particles in the electron microscope, showed that gold particles were frequently concentrated in the mitochondria in all the
cartilage zones and lay mainly within the organelles, not at their periphery. The endoplasmic reticulum contained moderate
immunoreactivity and there were few gold particles in the cytoplasm and nuclei. The number of gold particles decreased in
all the subcellular compartments from proliferative to hypertrophic chondrocytes. In contrast, Bax immunoreactivity changed
little during chondrocyte terminal evolution, and its subcellular distribution mirrored that of Bcl-2. These immunocytochemical
data indicate that Bcl-2 helps maintain chondrocytes and osteoblasts until their terminal maturation.
Accepted: 19 February 1997 相似文献
62.
IL-6受体结构与功能的研究进展 总被引:1,自引:0,他引:1
IL-6是一个多功能的细胞因子,其生物学作用在很大程度上受IL-6受体(IL-6R)结构和功能的影响。IL-6R由两条多肽链组成,即配体结合链gp80和信号传导链gp130。它们在结构和功能上既有分工又有合作。两种亚基组成的高和力IL-6R是介导细胞效应所必需的。IL-6Rα中的造血功能区属于造血因子受体超家族成员,它决定着结合IL-6的能力,然而gp130则是多种细胞因子共用的信号传递分子,其胞 相似文献
63.
Protoplasts were isolated from cortical cells of the elongating zone of maize (Zea mays L. cv. LG 11) roots and submitted to microelectrophoresis. Significant and transient differences in zeta potential between protoplasts from upper and lower root sides were compared with the gravireaction and the differential elongation of these roots. The maximum difference in the zeta potential was obtained between protoplasts from the upper and lower cortical cells after 90 min, exactly the time of gravipresentation for which the maximum rate of gravireaction was observed. In addition, this almost corresponded to the time for which the difference between the elongation rates of upper and lower sides of the extending zone began to increase. Consequently, the changes in the charges of the plasmalemma of the cortical cells from the growing part of roots could be more or less directly related to the root graviresponse. 相似文献
64.
65.
The endoplasmic reticulum from maize coleoptiles elongates stearoyl-CoA more effectively than the plasmalemma-enriched fraction. The alkane and very lo 相似文献
66.
Odile Gateau Maria Rocha de Morillo Pierre Louisot Renée Morelis 《生物化学与生物物理学报:生物膜》1980,595(1):157-160
A sialyl transferase activity is found in purified mitochondria. It is not due to residual contamination and this enzymatic system is located in the outer mitochondrial membrane. This proves mitochondrial autonomy in regard to glycoconjugate sialylation. 相似文献
67.
Gerhard Stucki René Gälli Hans-Rudolf Ebersold Thomas Leisinger 《Archives of microbiology》1981,130(5):366-371
A facultatively methylotrophic bacterium was isolated from enrichment cultures containing dichloromethane as the sole carbon source. It was identified as a Hyphomicrobium species. The organism grew exponentially in batch cultures with 10 mM dichloromethane at a specific growth rate of 0.07 h-1. The release of Cl- from dichloromethane and the disapperance of substrate paralleled growth. Resting dichloromethane-grown cells, in the presence of potassium sulphite as a trapping agent, converted cichloromethane methane quantitatively to formaldehyde. The conversion of dichloromethane to formaldehyde by cell extracts was stricly dependent on glutathione. Other thiols were inactive. Glutathione was not consumed in the course of the reaction. The specific activity of the enzymic dehalogenation of dichloromethane amounted to 3.8 mkat/kg protein in extracts of dichloromethane-grown cells and to less than 0.1 mkat/kg protein in extracts from cells grown on methanol. 相似文献
68.
In the present study, “in vitro” evidences are shown for the existence of a highly active 3α-hydroxysteroid dehydrogenase in the crude cytosol of rat muscle homogenates; the use of 5α-dihydrotestosterone (DHT) is therefore compromised in receptor binding measurements because of its extensive metabolism. The synthetic anabolic androgen, methyltrienolone (MT) palliates this disadvantage of DHT. Both steroids, as well as testosterone, appear to be bound to an 8–8.5 S androgen receptor on sucrose density gradient. The androgen receptor in the vastus and the levator ani bulbocavernosus complex (LA/BC) shows similar association constants, but the number of binding sites in LA/BC is about 5 times higher than in vastus. Otherwise, the total number of muscle androgen receptors seems to be invariant in adult and aged rats. The binding to these macromolecules can thus be measured “in vitro” provided specific and sensitive methods are utilized. 相似文献
69.
70.
A theoretical model is developed for continuous multistage enzyme production systems, which consist of a growth fermentor used for growing microorganisms rapidly without enzyme production and a subsequent system of induction reactors in which enzymes induction and production occurs. The model allows the computation of the fraction of induced cells residing in the induction reactor for organisms exhibiting a lag phase in enzyme induction. For this model a general analytical solution was obtained for the cumulative internal residence time distribution of a series of n well-stirred vessels with a recycle. The theoretical results are compared in a preliminary way with experimentally measured cellulase productivities of continuous multistage cellulose fermentations with Trichoderma viride QM 9414. 相似文献