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131.
Ants that resemble Camponotus maculatus (Fabricius, 1782) present an opportunity to test the hypothesis that the origin of the Pacific island fauna was primarily New Guinea, the Philippines, and the Indo‐Malay archipelago (collectively known as Malesia). We sequenced two mitochondrial and four nuclear markers from 146 specimens from Pacific islands, Australia, and Malesia. We also added 211 specimens representing a larger worldwide sample and performed a series of phylogenetic analyses and ancestral area reconstructions. Results indicate that the Pacific members of this group comprise several robust clades that have distinctly different biogeographical histories, and they suggest an important role for Australia as a source of Pacific colonizations. Malesian areas were recovered mostly in derived positions, and one lineage appears to be Neotropical. Phylogenetic hypotheses indicate that the orange, pan‐Pacific form commonly identified as C. chloroticus Emery 1897 actually consists of two distantly related lineages. Also, the lineage on Hawai?i, which has been called C. variegatus (Smith, 1858), appears to be closely related to C. tortuganus Emery, 1895 in Florida and other lineages in the New World. In Micronesia and Polynesia the C. chloroticus‐like species support predictions of the taxon‐cycle hypothesis and could be candidates for human‐mediated dispersal.  相似文献   
132.
133.
Restoration of riparian vegetation along large rivers is complicated by the patchiness of the habitat and by conflicts with the societal need to control flooding. The Sacramento River Project, led by The Nature Conservancy in northern California, is testing whether it is possible to restore native forest along a large river without removing flood control. We conducted a post-hoc analysis of monitoring data collected by the project on 1–4-year old plantings of 10 native trees and shrubs at five sites. Two questions of general interest were: Can one identify types of species or sites that are especially suitable for restoration in such riparian habitats? To what degree must sites be treated as mosaics of patches, with different types of patches that are suited to different species? Plant performance as measured by height was better in species of Salicaceae or in species planted as cuttings than in species of other families or in species planted as seedings or seeds. Three within-site factors, land form, soil depth to a buried layer of sand or gravel, and soil texture, affected the growth of several species, indicating that sites do need to be treated as patchy. However, there was little evidence that different species performed better on different types of patches. Instead, areas with deep or fine soils seemed to be favorable for a number of species. Results suggest that it is feasible to re-establish native trees and shrubs along large, regulated rivers, at least at certain sites for an initial period of several years with the aid of weed control and irrigation. Shallowly buried layers or lenses of gravel or sand are a hidden, fine-scale factor that can reduce plant growth on river terraces.  相似文献   
134.
IL-4 is a cytokine which can induce B-lymphocyte proliferation, increase cell-surface Ia expression, and induce some activated B cells to differentiate and begin to secrete IgE. IL-4 binds specifically to a cell-surface receptor (IL-4R) on cells from a variety of lineages including T and B cells. In general both primary cells and in vitro cell lines express less than 5000 receptors per cell. Utilizing a subclone of the cytotoxic T cell line CTLL-2 expressing a high level of IL-4R, mAb against the murine IL-4R were prepared. Two mAb have been identified which have different properties. These antibodies, designated M1 and M2, recognize sequences specific to the murine IL-4R. Immunoprecipitation studies with M1 and M2 on CTLL-2 cells have identified the receptor as a Mr = 145,000 cell-surface protein. Similar results have been obtained with the recently isolated full length murine IL-4R cDNA expressed in COS-7 cells. In addition the antibodies are capable of inhibiting IL-4 binding. One antibody, M1, is also a potent inhibitor of IL-4-induced proliferation. These antibodies will be useful in dissecting a wide array of activities attributed to IL-4.  相似文献   
135.
The efficacy of electromyographic feedback training in reducing the magnitude and frequency of the oral-lingual movements associated with tardive dyskinesia (TD) was investigated in a groups design. Twenty adult male inpatients diagnosed as having TD using the Abnormal Involuntary Movements Scale (AIMS) were randomly assigned to one of two treatment conditions. Following identification, all participants were initially reduced to the lowest effective dosage of neuroleptics, and then discontinued from anticholinergics. Following one month on this regimen, they were given a course of feedback training consisting of ten 14-minute sessions. Group one participants were provided with a tone contingent upon oral-lingual movements above a yoked threshold. Group two participants were given noncontingent feedback tones generated randomly. Weekly AIMS were administered as well as an initial baseline during each session to determine current level of oral-lingual activity. An analysis of session effects indicated significantly more suppression of oral-lingual activity in the contingent group versus the noncontingent feedback group. Jaw and forehead activity also measured showed reductions of similar magnitudes for both groups.  相似文献   
136.
果实颜色的多态性在植物界普遍存在,但是其维持机制尚不清楚。一些假说认为扩散者会偏好一些果色形态,但也有其它假说认为不同的果色形态具有各异的前扩散或后扩散适合度。我们比较分析了中国中南部野生二倍体五叶草莓(Fragaria pentaphylla)红白果型种群的遗传多样性、克隆多样性、交配系统、与抗冻性有关的形态特征以及子代的萌发、存活和种子产量等特征。五叶草莓红果型远远多于白果型,但基于观察到的有效等位基因数、香农信息指数、预期或观察到的杂合度数量等指标,红果型并未表现出更高的遗传多样性。分子方差分析(AMOVA)表明,大多数种群的遗传变异存在于红白果型内,而不是在红白果型间。红白果型的交配系统参数没有差异,且红白果型均未发现存在显著的双亲近交。红白果型间的基因流很高(Nm=6.89)。与白果型相比,红果型的种子的种子萌发约早2天,萌发率高出40%,但红白果型间的幼苗存活率和子代的种子产量没有差异。红果型总的扩散后适合度是白果型的2倍左右。红果型叶柄毛较多,但叶表面蜡质不多。综上所述,研究结果部分证据表明不同颜色形态的五叶草莓果实在扩散前后的适合度存在差异。因此,与扩散无关的适合度的差异部分解释了所有情况下果实颜色的多态性。  相似文献   
137.
The ALVAC-HIV/AIDSVAX-B/E RV144 vaccine trial showed an estimated efficacy of 31%. RV144 secondary immune correlate analysis demonstrated that the combination of low plasma anti-HIV-1 Env IgA antibodies and high levels of antibody-dependent cellular cytotoxicity (ADCC) inversely correlate with infection risk. One hypothesis is that the observed protection in RV144 is partially due to ADCC-mediating antibodies. We found that the majority (73 to 90%) of a representative group of vaccinees displayed plasma ADCC activity, usually (96.2%) blocked by competition with the C1 region-specific A32 Fab fragment. Using memory B-cell cultures and antigen-specific B-cell sorting, we isolated 23 ADCC-mediating nonclonally related antibodies from 6 vaccine recipients. These antibodies targeted A32-blockable conformational epitopes (n = 19), a non-A32-blockable conformational epitope (n = 1), and the gp120 Env variable loops (n = 3). Fourteen antibodies mediated cross-clade target cell killing. ADCC-mediating antibodies displayed modest levels of V-heavy (VH) chain somatic mutation (0.5 to 1.5%) and also displayed a disproportionate usage of VH1 family genes (74%), a phenomenon recently described for CD4-binding site broadly neutralizing antibodies (bNAbs). Maximal ADCC activity of VH1 antibodies correlated with mutation frequency. The polyclonality and low mutation frequency of these VH1 antibodies reveal fundamental differences in the regulation and maturation of these ADCC-mediating responses compared to VH1 bNAbs.  相似文献   
138.
Eliciting neutralizing antibodies is thought to be a key activity of a vaccine against human immunodeficiency virus (HIV). However, a number of studies have suggested that in addition to neutralization, interaction of IgG with Fc gamma receptors (FcγR) may play an important role in antibody-mediated protection. We have previously obtained evidence that the protective activity of the broadly neutralizing human IgG1 anti-HIV monoclonal antibody (MAb) b12 in macaques is diminished in the absence of FcγR binding capacity. To investigate antibody-dependent cellular cytotoxicity (ADCC) as a contributor to FcγR-associated protection, we developed a nonfucosylated variant of b12 (NFb12). We showed that, compared to fully fucosylated (referred to as wild-type in the text) b12, NFb12 had higher affinity for human and rhesus macaque FcγRIIIa and was more efficient in inhibiting viral replication and more effective in killing HIV-infected cells in an ADCC assay. Despite these more potent in vitro antiviral activities, NFb12 did not enhance protection in vivo against repeated low-dose vaginal challenge in the simian-human immunodeficiency virus (SHIV)/macaque model compared to wild-type b12. No difference in protection, viral load, or infection susceptibility was observed between animals given NFb12 and those given fully fucosylated b12, indicating that FcγR-mediated activities distinct from FcγRIIIa-mediated ADCC may be important in the observed protection against SHIV challenge.  相似文献   
139.
To study the impact of nutritional factors on protein expression of intestinal bacteria, gnotobiotic mice monoassociated with Escherichia coli K-12 were fed three different diets: a diet rich in starch, a diet rich in nondigestible lactose, and a diet rich in casein. Two-dimensional gel electrophoresis and electrospray-tandem mass spectrometry were used to identify differentially expressed proteins of bacteria recovered from small intestine and cecum. Oxidative stress response proteins such as AhpF, Dps, and Fur, all of which belong to the oxyR regulon, were upregulated in E. coli isolates from mice fed the lactose-rich diet. Luciferase reporter gene assays demonstrated that osmotic stress caused by carbohydrates led to the expression of ahpCF and dps, which was not observed in an E. coli ΔoxyR mutant. Growth of ahpCF and oxyR deletion mutants was strongly impaired when nondigestible sucrose was present in the medium. The wild-type phenotype could be restored by complementation of the deletions with plasmids containing the corresponding genes and promoters. The results indicate that some OxyR-dependent proteins play a major role in the adaptation of E. coli to osmotic stress. We conclude that there is an overlap of osmotic and oxidative stress responses. Mice fed the lactose-rich diet possibly had a higher intestinal osmolality, leading to the upregulation of OxyR-dependent proteins, which enable intestinal E. coli to better cope with diet-induced osmotic stress.  相似文献   
140.
Heat, mechanics, and myosin ATPase in normal and hypertrophied heart muscle   总被引:2,自引:0,他引:2  
In this paper we review our previous work on the myothermic economy of isometric force production in compensated cardiac hypertrophy secondary to pulmonary artery constriction (pressure overload) and/or thyrotoxicosis (volume overload). Hypertrophy-induced changes in isotonic and isometric twitch mechanics are correlated with accompanying changes in actin-activated myosin ATPase and heat liberation. Heat measurements were made with rapid, high-sensitivity thermopiles on right ventricular papillary muscles from normal and hypertrophied rabbit hearts. Total activity-related heat was separated into initial and recovery heat. Initial heat was separated into a tension-dependent component (TDH) relating to cross-bridge activity, and a tension-independent component (TIH) relating to excitation-contraction coupling. There were oppositely directed changes in most parameters studied in pressure overload hypertrophy (P) as compared with thyrotoxic hypertrophy (T). Thus, in P there was depression (30-50% in the rate of isometric force production, mechanical Vmax, TDH and TDH rate, myosin ATPase, TIH, and prolongation in time-to-peak twitch tension, whereas in T all parameters were oppositely changed except for no change in TIH. Thyrotoxicosis following pressure overload reversed the P-induced changes in all parameters. There was a direct, linear relation between in vitro actin-activated myosin ATPase and in vivo TDH. However, TDH per unit twitch tension or tension-time integral varied inversely with ATPase, making force production more economical than normal in P muscles and less economical than normal in T muscles. These cellular changes beneficially equip P hearts for slow, high-pressure, economical pumping the T hearts for fast, high-volume, uneconomical pumping. The differences are similar to those between slow and fast skeletal muscle and between neonatal and adult skeletal muscle. The mechanism of these changes is discussed in terms of an enzyme kinetic scheme of chemomechanical coupling in actomyosin interaction.  相似文献   
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