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101.
Extracellular matrix (ECM) modulates the EGF-induced migration of liver epithelial cells in serum-free,hormone-supplemented medium 总被引:2,自引:0,他引:2
Summary The influence of the extracellular matrix (ECM) glycoproteins collagen, IV laminin (LN), and fibronectin (FN) on the in vitro
migration of epithelial cells was studied using the ECM migration track method (4) with preparations immunostained for LN
and FN. The locomotion of rat liver epithelial cells stimulated to migrate in serum-free medium by epidermal growth factor
(EGF) in the presence of the protein per cm2. Neither LN nor collagen IV decreased the number of migrating cells, indicating that the inhibition is a specific effect
of fibronectin. The data also indicate that the FN-mediated inhibition of migration is an additional and not alternative mechanism
to the well-established contact inhibition of locomotion (1) which also occurs in liver epithelial cell cultures. The system
is being used for a further analysis of the factors that influence migration of normal and neoplastic epithelial cells and
the biochemical mechanisms underlying the migration reaction.
Editor’s Statement This paper describes new and heretofore neglected aspects of EGF and fibronectin action on the migratory
behavior of cultured cells. Gordon H. Sato 相似文献
102.
用含80%1,4-丁二醇的混合溶剂,以胰蛋白酶酶促,由去八肽胰岛素(DOI)合成了去六肽胰岛素(DHI),总产率为35%。1,4-丁二醇的溶解性能好,在浓度高达80—90%时不明显抑制酶活力,DOI的氨基无需保护,溶液中无高聚物或沉淀形成。 相似文献
103.
Patsy M. Brannon Bonnie M. Orrison Norman Kretchmer 《In vitro cellular & developmental biology. Plant》1985,21(1):6-14
Summary Rat pancreatic acinar cells were isolated and cultured in Ham's F12 medium with 15% bovine calf serum. Caerulein, insulin,
somatostatin, and dexamethasone (DEX) had no effect on intracellular or secreted amylase in these cultured cells. A serum-free
medium, using Waymouth's MB 752/1 supplemented with albumin, epidermal growth factor (EGF), DEX, and HEPES, was then developed
to avoid serum factors that might mask hormonal effects. In this SF medium, pancreatic acinar, cells maintained the morphological
and ultrastructural characteristics of freshly isolated cells and secreted amylase in response to the secretagogue, carbamyl
choline. Insulin, at a concentration of 1 μg/ml, significantly increased intracellular and secreted amylase activity after
3 d. This model cell system can be used to study the regulation of the synthesis of amylase and other pancreatic enzymes in
vitro. 相似文献
104.
Charles N. Serhan Mats Hamberg Bengt Samuelsson 《Biochemical and biophysical research communications》1984,118(3):943-949
Addition of 15L-hydroperoxy-5,8,11,13-eicosatetraenoic acid (15-HPETE) to human leukocytes led to the formation of a novel series of compounds containing four conjugated double bonds. The yield of tetraenes was increased approx. 100-fold when ionophore A23187 (5 μM) was added simultaneously with 15-HPETE. The structure of the major tetraene was established by physical methods as well as by chemical degradation and found to be 5,6,15L-trihydroxy-7,9,11,13-eicosatetraenoic acid. 相似文献
105.
Summary DNA sequencing has revealed an internal, tandemly repetitive structure in the family of giant polypeptides encoded by three types of Balbiani ring (BR) genes, in three different species ofChironomus. Each major BR repeat can be subdivided into two halves: a region consisting of short subrepeats and a more constant region that lacks obvious subrepeats. Comparative predictions of secondary structure indicate that an -helical segment is consistently present in the amino-terminal half of the constant region in all known BR proteins. Comparative predictions, coupled with consideration of the known phosphorylation of serine and threonine residues in BR proteins, suggest that the -helical structure may also extend into the carboxy-terminal half of the constant region, possibly interrupted by -turn(s). However, it is also possible that the structure is variable, and that a -strand is present in that half in some cases. All of the constant regions conserve one methionine and one phenylalanine residue, as well as all four cysteines; these residues presumably play roles in the packing or cross-linking of aligned constant regions. The structure of the subrepeat region is not clear, but the prevalence of a tripeptide pattern (basic-proline-acidic) suggests some type of structural regularity, possibly an extended helix. The possible significance of these conserved molecular features is discussed in the context of how they may serve the elasticity, insolubility, and hydrophilicity of the fibrils and threads formed by the BR polypeptides. 相似文献
106.
Summary New cell lines, designated as ML-DmDl≈10, were established from dissociated imaginal discs ofDrosophila melanogaster. The culture medium was prepared by mixing in a 1:1 ratio Cross and Sang’s M3(BF) medium, supplemented with 10% heat inactivated
fetal bovine serum (FBS), with the supernatant of a primary embryonic cell culture made in the M3(BF) medium and supplementing
this mixture with insulin. One cell line was established in the medium containing larval hemolymph instead of the primary
culture supernatan, and another was established in fresh M3(BF) medium supplemented with insulin and FBS. In these mediums,
imaginal disc cells first formed aggregates and cellular vesicles within a few weeks followed by the proliferation of thin-layered
cells around them after about 1 mo. Ten cell lines have so far been established from two kinds of imaginal discs and disc
mixtures. The ploidy of these cell lines was predominantly diploid. Population doubling time was about 50 to 70 h at 3 to
10 mo. after initiation of the culture. When the cell aggregates formed in vitro were implanted in metamorphosing larvae,
they differentiated at high frequency into adult cuticular strutures in the early phase of the primary culture. This differentiation
of aggregates was also observed, though at low frequency, in a culture maintained by dilution-transfer for 6 to 15 mo. in
vitro. 相似文献
107.
Summary Newborn rat adipocyte precursors, isolated from inguinal fat pads of 2 day-old NBR rats proliferate and undergo adipose differentiation
in defined medium in the absence of serum when cultivated on polylysine coated dishes in DME-F12 medium supplemented with
fibronectin, insulin, transferrin and FGF. After 7 days in culture in these conditions, 90% of the cells have undergone differentiation
as measured by the increase of G3PDH specific activity and by the accumulation of triglycerides in their cytoplasm. In contrast,
the cells cultivated in the presence of 10% fetal bovine serum, have a limited ability to differentiate. These results indicate
that newborn rat adipocyte precursors from inguinal fat pads do not require the presence of an undefined adipogenic factor
in order to differentiate in culture. In contrast, proliferation and differentiation are dependent on the presence of insulin
in the culture medium. Moreover, the data presented in this paper show that the rat adipocyte precursor culture represents
a rapid and reproducible system for investigating the processes of adipose tissue development and for studying the negative
and positive regulators of the adipose differentiation in a controlled environment.
This work was supported by grants from the Juvenile Diabetes Foundation, File #185221 and from the National Institutes of
Health 1 PO1 CA37589.
Editor’s Statement This paper extends to primary cultures the serum-free methods previously applied to studies of adipocyte
differentiation in established lines. The observation that serum can block differentiation in this system suggests the existence
of previously unrecognized circulating plasma or platelet factors affecting adipocyte differentiation, and the model developed
provides an assay for the identification of these factors. 相似文献
108.
Summary During an earlier investigation, microtubules were observed at the periphery of invasion processes in the developing syncytial tapetum ofTradescantia virginiana L. They were also associated with membranous sacs that accumulate adjacent to tetrads, with putative fusion sites where the tapetal plasmodium is initiated, and, in postmeiotic stages, with the perispore membrane that encloses the developing spore cells. Colchicine was administered to developing flower buds to investigate the roles of these microtubules. The results indicate that microtubules neither initiate nor guide the tapetal invasion of the loculus. The treatments, however, resulted in absence of cell coat from invasion processes and prevention of cell fusion. They also inhibited polarized migration of membrane sacs and removed the associated microtubules. The development of an organized secretory apparatus at the perispore membrane was disrupted, with subsequent disordered deposition of sporopollenin in the extracellular spaces of the partially-fused plasmodium. The results suggest that microtubules participate in the formation and internal spatial organization of the tapetal plasmodium, and establishment of a secretory surface that normally produces sporopollenin at the tapetum-microspore interface. 相似文献
109.
The purpose of this study was to determine and compare the follicular phase steroid hormone secretion into the utero-ovarian
vein by the ovary with a dominant follicle and the contralateral ovary in the same baboon. Serial utero-ovarian vein blood
from both sides was collected in 25 baboons by the use of a laparoscope on alternate days, starting on day 1 or 3 of the cycle
and continuing through 2 to 3 days post-ovulation. Approximately 3–4 days before the day of expected ovulation, samples were
collected at 8-hr intervals. Steroids estradiol (E2) and progesterone (P) were measured in all utero-ovarian vein plasma by radioimmunoassay. In the peripheral plasma, E2, P, LH, and FSH measurements were carried out. Concentrations of steroids were significantly higher on the side of the ovulating
ovary by day 5 before ovulation. Individual plots however, indicated that some baboons may establish the dominant side as
early as day 11 before ovulation. The preovulatory gonadotropins had a differential effect on the two ovaries. For example,
E2 values on the ovulatory side ovary declined after increases in LH/FSH, whereas on the contralateral side these values had
increased. Both sides showed increases in the level of P with the increases in LH. The mean interval from E2 peak to LH peak was 24 hrs and LH peak to ovulation was 24 hrs. 相似文献
110.
Insulin (100 U/ml) stimulated protein synthesis and PGF2 release in isolated rabbit muscle, but had little effect on the rate of protein degradation. The effect of insulin persisted for at least 5 h after removal of the hormone. Indomethacin, added at the start of the incubation, inhibited the stimulatory effect of insulin on protein synthesis and PGF2 release, but did not block the binding of iodinated insulin. When added 2 h after insulin, indomethacin did not inhibit the stimulation of protein synthesis but completely inhibited the increase in PGF2 release. The results suggest that the stimulation of protein synthesis by insulin is mediated by metabolites of membrane phospholipids but that these changes are involved during the phase of response that immediately follows the binding of insulin to its receptor. 相似文献