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961.
U Matern L Oberer R A Falchetto M Erhard W A K?nig M Herdman J Weckesser 《Phytochemistry》2001,58(7):1087-1095
Two novel cyclic depsipeptides were isolated from axenic cultures of the terrestrial cyanobacterium Scytonema hofmanni PCC 7110 and designated scyptolin A and B. Amino acid analyses in context with mass and 1H/13C NMR spectroscopies revealed a composition typical for heterologous cyanopeptolins but containing the uncommon residue 3'-chloro-N-methyl-Tyr (cmTyr) and a unique sidechain. Scyptolin A and B both consist of the N-acylated peptide But(1)-Ala(2)-Thr(3)-Thr(4)-Leu(5)-Ahp(6) (3-amino-6-hydroxy-2-oxo-1-piperidine)-Thr(7)-cmTyr(8)-Val(9), which forms a 19-membered ring by esterification of the carboxyl of Val(9) with the hydroxyl of Thr(4). In scyptolin B, the hydroxyl of the Thr(3) residue is additionally esterified with N-butyroyl-Ala. Both scyptolin A and B exhibit selective inhibition of porcine pancreatic elastase in vitro with IC(50) values of 3.1 microg/ml. 相似文献
962.
CD19‐CAR engineered NK‐92 cells are sufficient to overcome NK cell resistance in B‐cell malignancies 下载免费PDF全文
Annette Romanski Christoph Uherek Gesine Bug Erhard Seifried Hans Klingemann Winfried S. Wels Oliver G. Ottmann Torsten Tonn 《Journal of cellular and molecular medicine》2016,20(7):1287-1294
Many B‐cell acute and chronic leukaemias tend to be resistant to killing by natural killer (NK) cells. The introduction of chimeric antigen receptors (CAR) into T cells or NK cells could potentially overcome this resistance. Here, we extend our previous observations on the resistance of malignant lymphoblasts to NK‐92 cells, a continuously growing NK cell line, showing that anti‐CD19‐CAR (αCD19‐CAR) engineered NK‐92 cells can regain significant cytotoxicity against CD19 positive leukaemic cell lines and primary leukaemia cells that are resistant to cytolytic activity of parental NK‐92 cells. The ‘first generation’ CAR was generated from a scFv (CD19) antibody fragment, coupled to a flexible hinge region, the CD3ζ chain and a Myc‐tag and cloned into a retrovirus backbone. No difference in cytotoxic activity of NK‐92 and transduced αCD19‐CAR NK‐92 cells towards CD19 negative targets was found. However, αCD19‐CAR NK‐92 cells specifically and efficiently lysed CD19 expressing B‐precursor leukaemia cell lines as well as lymphoblasts from leukaemia patients. Since NK‐92 cells can be easily expanded to clinical grade numbers under current Good Manufactoring Practice (cGMP) conditions and its safety has been documented in several phase I clinical studies, treatment with CAR modified NK‐92 should be considered a treatment option for patients with lymphoid malignancies. 相似文献
963.
964.
Gerbino A Fistetto G Colella M Hofer AM Debellis L Caroppo R Curci S 《The Journal of biological chemistry》2007,282(18):13477-13486
The mechanisms for the formation of the osmotic gradient driving water movements in the gastric gland and its modulation via the extracellular Ca(2+)-sensing receptor (CaR) were investigated. Real time measurements of net water flux in the lumen of single gastric glands of the intact amphibian stomach were performed using ion-selective double-barreled microelectrodes. Water movement was measured by recording changes in the concentration of impermeant TEA(+) ions ([TEA(+)](gl)) with TEA(+)-sensitive microelectrodes inserted in the lumen of individual gastric glands. Glandular K(+) (K(+)(gl)) and H(+) (pH(gl)) were also measured by using K(+)- and H(+)-sensitive microelectrodes, respectively. Stimulation with histamine significantly decreased [TEA](gl), indicating net water flow toward the gland lumen. This response was inhibited by the H(+)/K(+)-ATPase inhibitor, SCH 28080. Histamine also elicited a significant and reversible increase in [K(+)](gl) that was blocked by chromanol 293B, a blocker of KCQN1 K(+) channels. Histamine failed to induce net water flow in the presence of chromanol 293B. In the "resting state," stimulation of CaR with diverse agonists resulted in significant increase in [TEA](gl). CaR activation also significantly reduced histamine-induced water secretion and apical K(+) transport. Our data validate the strong link between histamine-stimulated acid secretion and water transport. We also show that cAMP-dependent [K(+)](gl) elevation prior to the onset of acid secretion generates the osmotic gradient initially driving water into the gastric glands and that CaR activation inhibits this process, probably through reduction of intracellular cAMP levels. 相似文献
965.
966.
Susana Carolina Martins Ferreira Heribert Hofer Luis Madeira de Carvalho Marion L. East 《Ecology and evolution》2019,9(15):8783-8799
There are substantial individual differences in parasite composition and infection load in wildlife populations. Few studies have investigated the factors shaping this heterogeneity in large wild mammals or the impact of parasite infections on Darwinian fitness, particularly in juveniles. A host's parasite composition and infection load can be shaped by factors that determine contact with infective parasite stages and those that determine the host's resistance to infection, such as abiotic and social environmental factors, and age. Host–parasite interactions and synergies between coinfecting parasites may also be important. We test predictions derived from these different processes to investigate factors shaping infection loads (fecal egg/oocyte load) of two energetically costly gastrointestinal parasites: the hookworm Ancylostoma and the intracellular Cystoisospora, in juvenile spotted hyenas (Crocuta crocuta) in the Serengeti National Park, in Tanzania. We also assess whether parasite infections curtail survival to adulthood and longevity. Ancylostoma and Cystoisospora infection loads declined as the number of adult clan members increased, a result consistent with an encounter‐reduction effect whereby adults reduced encounters between juveniles and infective larvae, but were not affected by the number of juveniles in a clan. Infection loads decreased with age, possibly because active immune responses to infection improved with age. Differences in parasite load between clans possibly indicate variation in abiotic environmental factors between clan den sites. The survival of juveniles (<365 days old) to adulthood decreased with Ancylostoma load, increased with age, and was modulated by maternal social status. High‐ranking individuals with low Ancylostoma loads had a higher survivorship during the first 4 years of life than high‐ranking individuals with high Ancylostoma loads. These findings suggest that high infection loads with energetically costly parasites such as hookworms during early life can have negative fitness consequences. 相似文献
967.
Erhard Reschenhofer 《Biometrical journal. Biometrische Zeitschrift》1995,37(8):957-964
Standard tests for the detection of hidden periodicities in time series are largely ignored by applied workers. Various simple but inappropriate methods are used instead. Therefore a method is suggested which is both simple and appropriate but which requires the prior knowledge of certain characteristics of the suspected periodicity. For illustration, this method is applied to a set of data from a chronobiological study. 相似文献
968.
969.
970.
Guanghu Wang Kannan Krishnamurthy Nagavedi S. Umapathy Alexander D. Verin Erhard Bieberich 《The Journal of biological chemistry》2009,284(21):14469-14475
Atypical protein kinase Cs (PKCs) (aPKCζ and λ/ι) have
emerged as important binding partners for ceramide, a membrane-resident cell
signaling lipid that is involved in the regulation of apoptosis as well as
cell polarity. Using ceramide overlay assays with proteolytic fragments of
PKCζ and vesicle binding assays with ectopically expressed protein, we
show that a protein fragment comprising the carboxyl-terminal 20-kDa sequence
of PKCζ (C20ζ, amino acids 405–592) bound to C16:0 ceramide.
This sequence is not identical to the C1 domain (amino acids 131–180),
which has been suggested to serve as a potential ceramide binding domain.
Using immunocytochemistry, we found that a C20ζ protein fragment
ectopically expressed in two epithelial cell types (neural progenitors and
Madin-Darby canine kidney cells) co-distributed with ceramide. Stable
expression of C20ζ-EGFP in Madin-Darby canine kidney cells disrupted the
formation of adherens and tight junctions and impaired the epithelium
integrity by reducing transepithelial electrical resistance. Disruption of
cell adhesion and loss of transepithelial electrical resistance was prevented
by incubation with C16:0 ceramide. Our results show, for the first time, that
there is a novel ceramide binding domain (C20ζ) in the carboxyl terminus
of aPKC. Our results also show that the interaction of ceramide with this
binding domain is essential for cell-to-cell contacts in epithelia. Therefore,
ceramide interaction with the C20ζ binding domain is a potential
mechanism by which ceramide and aPKC regulate the formation of junctional
complexes in epithelial cells.Epithelial cells play essential roles in multicellular organisms by forming
physiological and mechanical barriers and controlling tissue architecture,
because they acquire apicobasal and cell-to-cell (planar) polarity
(1,
2). Adherens junctions
(AJs)2 and tight
junctions (TJs) are major structures responsible for cell-to-cell adhesion in
epithelial cells (3). The
regulation of junction formation requires endocytosis, redistribution, and
recycling of junctional proteins, such as E-cadherin
(4), and ZO-1. Many factors,
including EGF, EGFR, Src kinase, Rho family GTPases Cdc42 and Rac1, and
atypical PKC (aPKC), have been found to regulate junction formation
(5–9).
In Madin-Darby canine kidney (MDCK) cells, Cdc42 modulates AJs by regulating
E-cadherin ubiquitination and degradation
(9), whereas aPKC directly
localized at TJs is required for the asymmetric differentiation of the
premature junction complex during epithelial cell polarization
(1,
10).The protein kinase C (PKC) family comprises serine/threonine kinases, which
consist of a carboxyl-terminal catalytic domain and an amino-terminal
regulatory domain (Fig.
1A). The regulatory domain includes an inhibitory
pseudosubstrate domain and allosteric sites for activation by
phosphatidylserine and, depending on the isoform, calcium (C2 domain) and/or
diacylglycerol (C1 domain). aPKC is a subfamily of PKC, which consists of the
isoforms ζ and λ/ι. The aPKC isoforms contain only half of
the C1 domain, and hence, their activity is not affected by calcium or
diacylglycerol/phorbol esters (see Fig.
1A and Refs.
11–13).Open in a separate windowFIGURE 1.Binding of ceramide to the COOH terminus of PKCζ. A,
primary structure of aPKC, the caspase 3 proteolytic fragment ζCasp II,
and the NH2-terminal deletion mutant C20ζ-EGFP. B, 2
μg of recombinant His-tagged PKCζ was proteolytically digested by 20
ng of recombinant caspase 3. Proteolysis by caspase 3 occurred first after
amino acid 239 (4-h incubation) and then after amino acid 459 (10-h
incubation, ζCasp II). C, binding to ceramide spotted on
nitrocellulose (overlay assay). FL PKCζ and the COOH-terminal proteolytic
fragment ζCasp II bound to C16 ceramide. D, C16 ceramide vesicle
binding assay (LIMAC). Ectopically expressed C20ζ-EGFP prepared from a
cell lysate was bound to ceramide vesicles; EGFP was not. Protein was detected
using anti-aPKC and anti-GFP antibodies. Lanes 1–3, loading
input for ceramide vesicles; lanes 4–6, eluate of vesicle
binding columns (output). Lanes 7 (input) and 8 (output)
show that PKCζ-EGFP did not bind to vesicles prepared with sphingomyelin
(SM) instead of ceramide. E, subcellular fractionation of
cells expressing FL PKCζ-EGFP or C20ζ-EGFP.Apart from its function in apoptosis
(13–15)
and cell growth (16), aPKC has
been found to play a pivotal role in cell polarity, both in neuroepithelial
cells
(17–20)
or other epithelial cell types
(1,
10). Consistently, the gene
knock-out of aPKC shows loss of cell junction formation and detachment of
neural progenitor cells from the neuroepithelium
(8,
21–23).
We and others have found that the sphingolipid ceramide activates aPKC,
recruits it to structured microdomains, and regulates cell polarity and
motility
(24–28).
Using lipid vesicle-mediated affinity chromatography (LIMAC) assays, we showed
for the first time that ceramide directly binds to aPKC
(25). Yet which domain of aPKC
binds to ceramide is not known.Using lipid overlay and LIMAC assays, we show here that a COOH-terminal
20-kDa domain of PKCζ (C20ζ) binds to ceramide. Similar to its
full-length counterpart, the C20ζ protein fragment resides in cellular
membranes, where it co-distributes with ceramide in both C17.2 (neural
progenitor) and MDCK cells. To study the function of this ceramide binding
domain, we established a stably transfected MDCK cell line expressing
C20ζ-EGFP. In these cells, the protein level of E-cadherin is reduced,
and the cellular distribution of E-cadherin, ZO-1, and β-catenin is
disrupted when compared with EGFP-transfected cell lines. Further,
transepithelial electrical resistance (TER) assays show that the
C20ζ-EGFP cell line has reduced impedance when compared with the control
cell line expressing EGFP. This finding suggests that the C20ζ protein
fragment is a dominant negative mutant of PKCζ. The effects of this
dominant negative mutant can be, at least partially, rescued by incubation
with C16:0 ceramide, suggesting that ceramide regulates aPKC and
aPKC-dependent cell junction formation by interaction with the COOH-terminal
domain. 相似文献