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101.
Gagiannis D Orthmann A Danssmann I Schwarzkopf M Weidemann W Horstkorte R 《Glycoconjugate journal》2007,24(2-3):125-130
Sialic acids are widely expressed as terminal carbohydrates on glycoconjugates of eukaryotic cells. They are involved in a
variety of cellular functions, such as cell adhesion or signal recognition. The key enzyme of sialic acid biosynthesis is
the bifunctional UDP-N-acetylglucosamine-2-epimerase/N-acetylmannosamine kinase (GNE), which catalyzes the first two steps of sialic acid biosynthesis in the cytosol. Previously,
we have shown that inactivation of the GNE by gene targeting causes early embryonic lethality in mice, whereas heterozygous
GNE-deficient mice are vital. In this study we compared the amount of membrane-bound sialic acids of wildtype mice with those
of heterozygous GNE-deficient mice. For that we quantified membrane-bound sialic acid concentration in various organs of wildtype-
and heterozygous GNE-deficient mice. We found an organ-specific reduction of membrane-bound sialic acids in heterozygous GNE-deficient
mice. The overall reduction was 25%. Additionally, we analyzed transferrin and polysialylated neural cell adhesion molecule
(NCAM) by one- or two-dimensional gel electrophoresis. Transferrin-expression was unchanged in heterozygous GNE-deficient
mice; however the isoelectric point of transferrin was shifted towards basic pH, indicating a reduced sialylation. Furthermore,
the expression of polysialic acids on NCAM was reduced in GNE-deficient mice.
Daniel Gagiannis and André Orthmann have contributed equally to this work. 相似文献
102.
Müller WE Eckert C Kropf K Wang X Schlossmacher U Seckert C Wolf SE Tremel W Schröder HC 《Cell and tissue research》2007,329(2):363-378
The siliceous sponge Monorhaphis chuni (Hexactinellida) synthesizes the largest biosilica structures on earth (3 m). Scanning electron microscopy has shown that
these spicules are regularly composed of concentrically arranged lamellae (width: 3–10 μm). Between 400 and 600 lamellae have
been counted in one giant basal spicule. An axial canal (diameter: ~2 μm) is located in the center of the spicules; it harbors
the axial filament and is surrounded by an axial cylinder (100–150 μm) of electron-dense homogeneous silica. During dissolution
of the spicules with hydrofluoric acid, the axial filament is first released followed by the release of a proteinaceous tubule.
Two major proteins (150 kDa and 35 kDa) have been visualized, together with a 24-kDa protein that cross-reacts with antibodies
against silicatein. The spicules are surrounded by a collagen net, and the existence of a hexactinellidan collagen gene has
been demonstrated by cloning it from Aphrocallistes vastus. During the axial growth of the spicules, silicatein or the silicatein-related protein is proposed to become associated with
the surface of the spicules and to be finally internalized through the apical opening to associate with the axial filament.
Based on the data gathered here, we suggest that, in the Hexactinellida, the growth of the spicules is mediated by silicatein
or by a silicatein-related protein, with the orientation of biosilica deposition being controlled by lectin and collagen.
Carsten Eckert was previously with the Museum für Naturkunde, Invalidenstrasse 43, 10115 Berlin, Germany.
The collagen sequence from Aphrocallistes vastus reported here, viz., [COL_APHRO] APHVACOL (accession number AM411124), has been deposited in the EMBL/GenBank data base.
This work was supported by grants from the European Commission, the Deutsche Forschungsgemeinschaft, the Bundesministerium
für Bildung und Forschung Germany (project: Center of Excellence BIOTECmarin), the National Natural Science Foundation of China (grant no. 50402023), and the International Human Frontier Science
Program. 相似文献
103.
Drabczyńska A Müller CE Karolak-Wojciechowska J Schumacher B Schiedel A Yuzlenko O Kieć-Kononowicz K 《Bioorganic & medicinal chemistry》2007,15(14):5003-5017
Synthesis and physicochemical properties of N-benzyl pyrimido[2,1-f]purinediones are described. These derivatives were synthesized by the cyclization of 7-chloropropylo-8-bromo-1,3-dimethyl- or 1,3-dipropyl xanthine derivatives with corresponding (un)substituted benzylamines. Dipropyl derivatives were obtained under microwave irradiation conditions either. The obtained compounds (1-20) were evaluated for their affinity to adenosine A1 and A2A receptors, selected compounds were additionally investigated for affinity to the A3 receptor subtype. The results of the radioligand binding assays to A1 and A2A adenosine receptors showed that most of the 1,3-dimethyl-9-benzylpyrimidopurinediones exhibited selective affinity to A2A receptors at micromolar or submicromolar concentrations (for example, derivative 9 with o-methoxy substituent displayed a Ki value of 0.699 microM at rat A2A receptor with more than 36-fold selectivity). Contrary to previously described arylpyrimido[2,1-f]purinediones dipropyl derivatives (compounds 15-20) showed affinity to both kinds of receptors increased, however A1 affinity increased to a larger extent, with the result that A2A selectivity was abolished. The best adenosine A1 receptor ligand was m-chlorobenzyl derivative 18 (Ki=0.089 microM and 5-fold A1 selectivity). Structure-activity relationships were discussed with the analysis of lipophilic and spatial properties of the investigated compounds. Pharmacophore model of adenosine A1 receptor antagonist was adopted for this purpose. 相似文献
104.
Fusiogenic endogenous-retroviral syncytin-1 exerts anti-apoptotic functions in staurosporine-challenged CHO cells 总被引:1,自引:0,他引:1
Knerr I Schnare M Hermann K Kausler S Lehner M Vogler T Rascher W Meissner U 《Apoptosis : an international journal on programmed cell death》2007,12(1):37-43
Fusiogenic glycoprotein syncytin-1, expressed in human placenta, is a promising candidate for acquiring a basic knowledge
of placental syncytialization. However, its cellular mode of action is unidentified. We investigated whether syncytin-1 may
exert influence on apoptotic processes. Therefore, we incubated CHO cells after stable transfection with syncytin-1 (CHO-52)
in the presence or absence of staurosporine (STS), a kinase inhibitor well characterized to induce apoptosis. When testing
the phenotype of CHO-52 cells, we could demonstrate that the induction of apoptosis by STS was delayed over a period of up
to 24 h. Furthermore, the cell death rate was decreased by approx 75% following transfection of syncytin-1 in CHO-52 compared
to mock-treated cells. In detail, after 18h of incubation with 500 nM STS, 64 ± 2% of CHO-52 cells were viable compared to
16 ± 1% of CHO-mocks, after 24 h 43 ± 3% vs 5 ± 2%, respectively. CHO-52 cells exhibited a lower expression of active caspase
3 and anti-apoptotic Bcl-2 was found to be increased in CHO-52 cells at baseline and following STS treatment.
Our study provides first evidence that syncytin-1 serves anti-apoptotic function under certain conditions. A lessened activation
of caspase 3 and an increased expression of Bcl-2 are possible mechanisms. 相似文献
105.
Widl K Brettschneider J Schattauer D Süssmuth S Huber R Ludolph AC Tumani H 《Neurochemical research》2007,32(7):1163-1168
We aimed to establish age-related reference values for Erythropoietin (EPO) in cerebrospinal fluid (CSF) and to evaluate concentrations
in neurological diseases. CSF and serum EPO was measured in controls with tension-type headache (CTTH), in patients with ALS,
dementia and depression using ELISA technique.
Stability experiments showed CSF EPO to be stable for two and a half months and over two thaw/freeze cycles. A positive correlation
of CSF EPO with age was found (P < 0.01). We found a CSF/serum EPO concentration ratio of 0.126, pointing towards an intrathecal synthesis of EPO. The ALS
group showed significantly lowered CSF EPO compared to age-matched CTTH (P < 0.012), whereas the dementia and depression group showed no significant differences compared to CTTH.
The establishment of age-related reference values in a large cohort of controls will improve the interpretation of future
CSF EPO evaluations in neurological diseases.
The authors have not reported any conflicts of interest. 相似文献
106.
Fetal and early post-natal development of the human spleen: from primordial arterial B cell lobules to a non-segmented organ 总被引:2,自引:2,他引:0
Immunohistological analysis of 31 human spleens from the 11th week of gestation to the early postnatal period suggested that
fetal organ development may be preliminarily divided into four stages. At stage 0 the organ anlage contained erythrocyte precursors,
few macrophages and almost no lymphocytes. Fetal spleens of stage I exhibited arterial vascular lobules and lymphocytes just
began colonizing the organ. At stage II, B and T lymphocytes formed periarteriolar clusters. B cell clusters predominated,
because B cells aggregated around the more peripheral branches of splenic arterioles, while T cells occupied the more centrally
located parts of the vessels. The vascular lobules of stage I and II consisted of central arterioles surrounded by B cells,
capillaries and peripheral venules. The lobular architecture slowly dissolved at late stage II when sinuses grew out from
the peripheral venules into the centre of the lobule. Interestingly, the B cell accumulations around peripheral arterioles
did not represent the precursors of follicles, but apparently persisted as periarteriolar B cell clusters in the adult splenic
red pulp, while follicles containing FDCs developed at late stage II from B cells in direct contact to T cell clusters around
larger arterial vessels. At stage III before birth the lobular architecture was no longer recognized. The chemokine CXCL13
was already present in vascular smooth muscle and adjacent stromal cells at stage I before B cells immigrated. CCL21, on the
contrary, was only demonstrated in fibroblast-like cells supporting T cell clusters from stage II onwards. 相似文献
107.
Parvovirus (PV) B19 is the causative agent of the childhood disease erythema infectiosum. An association of PV B19 with chronic
arthropathies, sometimes resembling rheumatoid arthritis or juvenile idiopathic arthritis (JIA), has repeatedly been described.
Other studies, however, have failed to identify any such relationship. In order to study further whether there is a link between
PV B19 and JIA, we determined the prevalence of PV B19 specific IgG antibodies in serum samples from children with rheumatoid
diseases and compared it with the prevalence in unaffected children We reasoned that if there is an association between PV
B19 and JIA, then the prevalence of PV B19 IgG in the children with JIA should be higher than in the control group. PV B19
IgG status was tested in 406 children with JIA and related diseases, and in 146 children constituting a control group. The
percentage of PV B19 IgG positive children was not significantly elevated in the disease subgroups compared with age-matched
control groups. In conclusion, our findings do not support the hypothesis that human parvovirus B19 is involved in the pathogenesis
of JIA. 相似文献
108.
109.
Neuropeptide Y regulates the hematopoietic stem cell microenvironment and prevents nerve injury in the bone marrow 下载免费PDF全文
Woo‐Kie Min Won Woo Lee Jeong Eun Lee Haruhiko Akiyama Herbert Herzog Grigori N Enikolopov Edward H Schuchman Jae‐sung Bae 《The EMBO journal》2015,34(12):1648-1660
Many reports have revealed the importance of the sympathetic nervous system (SNS) in the control of the bone marrow environment. However, the specific role of neuropeptide Y (NPY) in this process has not been systematically studied. Here we show that NPY‐deficient mice have significantly reduced hematopoietic stem cell (HSC) numbers and impaired regeneration in bone marrow due to apoptotic destruction of SNS fibers and/or endothelial cells. Furthermore, pharmacological elevation of NPY prevented bone marrow impairments in a mouse model of chemotherapy‐induced SNS injury, while NPY injection into conditional knockout mice lacking the Y1 receptor in macrophages did not relieve bone marrow dysfunction. These results indicate that NPY promotes neuroprotection and restores bone marrow dysfunction from chemotherapy‐induced SNS injury through the Y1 receptor in macrophages. They also reveal a new role of NPY as a regulator of the bone marrow microenvironment and highlight the potential therapeutic value of this neuropeptide. 相似文献
110.
Transcriptome analysis of cyclic AMP‐dependent protein kinase A–regulated genes reveals the production of the novel natural compound fumipyrrole by Aspergillus fumigatus 下载免费PDF全文