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21.
The netrin family of axon guidance cues has been shown to play a pivotal role in the guidance of a variety of axon projections during embryonic development, both in the vertebrate and invertebrate. While the guidance potential of netrin-1 has been examined in depth in many regions of the developing mouse brain very little information is available on the expression and activity of netrin-3. Here we show that the netrin-3 protein is present on motor neurons and subpopulations of neurons within sensory and sympathetic ganglia. Moreover, significant levels of netrin-3 protein were found to be associated with the axons projecting from these neurons suggesting a role for netrin-3 in axon pathfinding and fasciculation within the peripheral nervous system.  相似文献   
22.
Inland salt lakes are widely distributed in southern Africa: they are particularly common in South Africa, but many occur in Namibia and Botswana. All are shallow, and most are ephemeral with salinities that are not very high (mostly < 50 g l−1). Fringing zones of halophytes or submerged macrophytes are neither well-developed nor taxonomically diverse. The Cyanobacteria, especially Nodularia spumigena, often dominate the phytoplankton. The fauna of the Makgadikgadi area (northeast Botswana) is diverse and is similar to that of East African salt lakes. The aquatic fauna of salt water south of the Makgadikgadi Basin, on the other hand, is extremely depauperate, has no well-defined assemblage confined to saline waters, and appears mostly to comprise tolerant freshwater forms. Lovenula falcifera and Metadiaptomus transvaalensis (diaptomid copepods), Moina micrura (Cladocera) and Brachionus plicatilis (Rotifera) are frequently encountered zooplankton species, a few species of insects (Anisops sp., beetles, chironomids and ephydrids) are the principal non-planktonic macroinvertebrates. Artemia ‘salina’ is occasionally present, but may be an introduced form. The avifauna, in contrast to the aquatic macroinvertebrate fauna, is rich, with the greater and lesser flamingo often common.  相似文献   
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Understanding the antibody response to HIV-1 in humans that show broad neutralizing serologic activity is a crucial step in trying to reproduce such responses by vaccination. Investigating antibodies with cross clade reactivity is particularly important as these antibodies may target conserved epitopes on the HIV envelope gp160 protein. To this end we have used a clade B YU-2 gp140 trimeric antigen and single-cell antibody cloning methods to obtain 189 new anti-gp140 antibodies representing 51 independent B cell clones from the IgG memory B cells of 3 patients infected with HIV-1 clade A or B viruses and exhibiting broad neutralizing serologic activity. Our results support previous findings showing a diverse antibody response to HIV gp140 envelope protein, characterized by differentially expanded B-cell clones producing highly hypermutated antibodies with heterogenous gp140-specificity and neutralizing activity. In addition to their high-affinity binding to the HIV spike, the vast majority of the new anti-gp140 antibodies are also polyreactive. Although none of the new antibodies are as broad or potent as VRC01 or PG9, two clonally-related antibodies isolated from a clade A HIV-1 infected donor, directed against the gp120 variable loop 3, rank in the top 5% of the neutralizers identified in our large collection of 185 unique gp140-specific antibodies in terms of breadth and potency.  相似文献   
25.
The aim of this study was to compare the effects of static stretching, proprioceptive neuromuscular facilitation (PNF) stretching and Mulligan technique on hip flexion range of motion (ROM) in subjects with bilateral hamstring tightness. A total of 40 students (mean age: 21.5±1.3 years, mean body height: 172.8±8.2 cm, mean body mass index: 21.9±3.0 kg · m-2) with bilateral hamstring tightness were enrolled in this randomized trial, of whom 26 completed the study. Subjects were divided into 4 groups performing (I) typical static stretching, (II) PNF stretching, (III) Mulligan traction straight leg raise (TSLR) technique, (IV) no intervention. Hip flexion ROM was measured using a digital goniometer with the passive straight leg raise test before and after 4 weeks by two physiotherapists blinded to the groups. 52 extremities of 26 subjects were analyzed. Hip flexion ROM increased in all three intervention groups (p<0.05) but not in the no-intervention group after 4 weeks. A statistically significant change in initial–final assessment differences of hip flexion ROM was found between groups (p<0.001) in favour of PNF stretching and Mulligan TSLR technique in comparison to typical static stretching (p=0.016 and p=0.02, respectively). No significant difference was found between Mulligan TSLR technique and PNF stretching (p=0.920). The initial–final assessment difference of hip flexion ROM was similar in typical static stretching and no intervention (p=0.491). A 4-week stretching intervention is beneficial for increasing hip flexion ROM in bilateral hamstring tightness. However, PNF stretching and Mulligan TSLR technique are superior to typical static stretching. These two interventions can be alternatively used for stretching in hamstring tightness.  相似文献   
26.
When distributional assumptions for analysis of variance are suspect, and nonparametric methods are unavailable, ecologists frequently employ rank transformation (RT) methods. The technique replaces observations by their ranks, which are then analysed using standard parametric tests. RT methods are widely recommended in statistics texts and in manuals for packages like SAS and IMSL. They are robust and powerful for the analysis of additive factorial designs. Recently, however, RT methods have been found to be grossly inappropriate for use with non-additive models. This severe limitation remains largely unreported outside of the theoretical statistics literature. Our goal is to explain this shortcoming of RT methods.  相似文献   
27.
Hydroxyethyl starch (HES) has often been used as a plasma expander, but questions still remain concerning the mechanisms by which it produces changes in the rheological properties of blood and erythrocyte (RBC) suspensions under various flow conditions. The present investigation has shown that the dynamic viscosity of HES (232,000 and 565,000 daltons) solutions rises in a nonlinear fashion with increasing HES concentration, and for a given concentration of HES exhibits Newtonian behavior at shear rates between 0.15 to 124 sec-1. At low (less than 0.9 sec-1) shear rates the apparent viscosity of a 40% RBC suspension increases with lower concentrations of HES because of RBC aggregation. At higher concentrations of HES, increases in suspension viscosity are due to an increase in the viscosity of the continuous phase since the RBC are largely disaggregated. At high (greater than 36 sec-1) shear rates the relative viscosity (eta/eta O) of RBC suspensions slowly decreases with increasing HES concentration. At low shear rates eta/eta O increases and then decreases with increasing HES concentration. Evidence of the concentration-dependent effects of HES on RBC aggregation is provided not only by the viscometric analysis but also from measurements of erythrocyte sedimentation rate (ESR) and the zeta sedimentation ratio (ZSR). HES is a more potent aggregating agent in phosphate buffered saline (PBS) than it is in plasma. Polymer size has only a slight effect on the extent of RBC aggregation produced, but does have a significant effect on the concentration of polymer at which maximum aggregation occurs. The viscosity-corrected electrophoretic mobility of RBC in HES rises monotonically with the concentration of HES in the suspending medium. Decreases in the extent of RBC aggregation with increasing polymer concentrations probably result from an increase in the electrostatic repulsive forces between the cells.  相似文献   
28.
Concanavalin A, at extremely low concentrations, will produce significant increases in the electrophoretic mobility of murine splenic T lymphocytes. It has been established that the alteration in cellular surface charge is mediated by a factor produced by those lymphocytes that have reacted directly with con A. We originally conjectured that the mobility change might be the consequence of an alteration in the distribution of the charged moieties of membrane glycoproteins. The results of experiments conducted at low temperature raise some questions about this mechanism. Further experiments have been performed to establish the nature of the physicochemical alterations in the peripheral zone of the factor-stimulated lymphocytes that are manifest as changes in cellular surface charge. The results of these studies indicate that, subsequent to the interaction of T lymphocytes with con A, there is a reduction in the number of positively charged amino groups effective at the electrophoretic surface of the cells.  相似文献   
29.
It is of interest to compile available information on the root canal morphology of primary maxillary molars from known literature. The literature resources used to collect data include Medline/PubMed, The Cochrane Central Register of Clinical Trials, SIGLE and Science Direct. Data consists of type of population, number of teeth per study, number of root canals, canal length and type of root canal configuration. We used data from a total of 13 studies (951 primary maxillary molars). Maxillary molars (1st and 2nd) are dominant for two roots variant. The first molar the mean root length ranges from 7.9mm - 8.1mm. The second molar ranges from 7.2mm-8.5mm. Type I (explain in a phrase) canal morphology is the common variant in both the molars. Data shows that Root Canal morphology shows variations with the diagnostic aid (example micro CT) used and in different ethnic populations.  相似文献   
30.
Endosome-to-Golgi retrieval of the cation-independent mannose 6-phosphate receptor (CIMPR) requires the function of the retromer complex. Retromer is localized to endosomes and comprises two distinct sub complexes: the vacuolar protein sorting 35/29/26 sub complex that binds cargo and the sorting nexin (SNX)1/2 sub complex that tubulates endosomal membranes. To identify up- or down-stream regulatory factors of retromer, a comparative proteomic strategy was employed. Protein profiles of endosomally enriched membranes, from either wild-type or retromer-deficient mouse cells, were compared to identify proteins with either elevated or reduced expression levels. Eps15 homology domain-containing protein-1 (EHD1) was identified in endosomally enriched membrane fractions from retromer-deficient cells and was found to be approximately threefold upregulated in the absence of retromer. EHD1 is localized to tubular and vesicular endosomes, partially colocalizes with retromer and is associated with retromer in vivo. Mutation of the nucleotide-binding P-loop of EHD1 results in a dominant-negative effect upon retromer localization and endosome-to-Golgi retrieval, while loss of EHD1 expression by RNA interference destabilizes SNX1-positive tubules and inhibits endosome-to-Golgi retrieval. The interaction between EHD1 and retromer and the requirement for EHD1 to stabilize SNX1-tubules establish EHD1 as a novel facilitating component of endosome-to-Golgi retrieval.  相似文献   
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