全文获取类型
收费全文 | 875篇 |
免费 | 64篇 |
专业分类
939篇 |
出版年
2023年 | 4篇 |
2022年 | 14篇 |
2021年 | 28篇 |
2020年 | 12篇 |
2019年 | 13篇 |
2018年 | 21篇 |
2017年 | 16篇 |
2016年 | 32篇 |
2015年 | 35篇 |
2014年 | 43篇 |
2013年 | 47篇 |
2012年 | 53篇 |
2011年 | 85篇 |
2010年 | 47篇 |
2009年 | 36篇 |
2008年 | 53篇 |
2007年 | 55篇 |
2006年 | 47篇 |
2005年 | 42篇 |
2004年 | 27篇 |
2003年 | 29篇 |
2002年 | 17篇 |
2001年 | 10篇 |
2000年 | 8篇 |
1999年 | 12篇 |
1997年 | 4篇 |
1996年 | 4篇 |
1995年 | 5篇 |
1993年 | 4篇 |
1992年 | 4篇 |
1991年 | 8篇 |
1990年 | 8篇 |
1989年 | 5篇 |
1988年 | 9篇 |
1987年 | 5篇 |
1986年 | 5篇 |
1983年 | 5篇 |
1981年 | 6篇 |
1979年 | 5篇 |
1977年 | 4篇 |
1976年 | 5篇 |
1975年 | 7篇 |
1974年 | 8篇 |
1971年 | 4篇 |
1970年 | 3篇 |
1969年 | 7篇 |
1968年 | 3篇 |
1967年 | 6篇 |
1966年 | 3篇 |
1965年 | 3篇 |
排序方式: 共有939条查询结果,搜索用时 15 毫秒
101.
Gracia-Marco L Valtueña J Ortega FB Pérez-López FR Vicente-Rodríguez G Breidenassel C Ferrari M Molnar D Widhalm K de Henauw S Kafatos A Diaz LE Gottrand F Maiani G Stehle P Castillo MJ Moreno LA González-Gross M;on behalf of the HELENA Study Group 《Journal of applied physiology (Bethesda, Md. : 1985)》2012,113(4):566-573
There is a lack of studies that analyze the association between micronutrient-related biomarker status and physical fitness in adolescents. In the present study, biochemical parameters for iron and vitamin status were studied, along with objective measures of physical fitness in healthy male and female European adolescents. One thousand eighty-nine adolescents (580 girls, 12.5-17.5 yr) from the Healthy Lifestyle in Europe by Nutrition in Adolescence (HELENA) cross-sectional study were included. Hierarchical linear models were performed to determine the associations between micronutrient biomarkers and physical fitness. Age, seasonality, latitude, body mass index, menarche (in girls), and physical activity were used as covariates. For cardiorespiratory fitness, concentrations of hemoglobin, retinol, and vitamin C in male adolescents and β-carotene and 25(OH)D in female adolescents were associated with maximal oxygen consumption. For muscular fitness, concentrations of hemoglobin, β-carotene, retinol, and α-tocopherol in male adolescents and β-carotene and 25(OH)D in female adolescents were associated with better performance of the standing long jump test. In summary, concentrations of hemoglobin and most antioxidant vitamins in male adolescents and β-carotene and 25(OH)D in female adolescents were positively associated with cardiorespiratory and muscular fitness, after controlling for relevant confounders. The associations between physical fitness and iron or vitamin status observed in this cross-sectional study in adolescents should be followed up by a study specifically designed to evaluate causal relationships. 相似文献
102.
Goudarzi M Banisch TU Mobin MB Maghelli N Tarbashevich K Strate I van den Berg J Blaser H Bandemer S Paluch E Bakkers J Tolić-Nørrelykke IM Raz E 《Developmental cell》2012,23(1):210-218
Single-cell migration is a key process in development, homeostasis, and disease. Nevertheless, the control over basic cellular mechanisms directing cells into motile behavior in?vivo is largely unknown. Here, we report on the identification of a minimal set of parameters the regulation of which confers proper morphology and cell motility. Zebrafish primordial germ cells rendered immotile by knockdown of Dead end, a negative regulator of miRNA function, were used as a platform for identifying processes restoring motility. We have defined myosin contractility, cell adhesion, and cortex properties as factors whose proper regulation is sufficient for restoring cell migration of this cell type. Tight control over the level of these cellular features, achieved through a balance between miRNA-430 function and the action of the RNA-binding protein Dead end, effectively transforms immotile primordial germ cells into polarized cells that actively migrate relative to cells in their environment. 相似文献
103.
Vorlíčková M Kejnovská I Sagi J Renčiuk D Bednářová K Motlová J Kypr J 《Methods (San Diego, Calif.)》2012,57(1):64-75
Circular dichroism (CD) is remarkably sensitive to the conformational states of nucleic acids; therefore, CD spectroscopy has been used to study most features of DNA and RNA structures. Quadruplexes are among the significant noncanonical nucleic acids architectures that have received special attentions recently. This article presents examples on the contribution of CD spectroscopy to our knowledge of quadruplex structures and their polymorphism. The examples were selected to demonstrate the potential of this simple method in the quadruplex field. As CD spectroscopy detects only the global feature of a macromolecule, it should preferably be used in combination with other techniques. On the other hand, CD spectroscopy, often as a pioneering approach, can reveal the formation of particular structural arrangements, to search for the conditions stabilizing the structures, to follow the transitions between various structural states, to explore kinetics of their appearance, to determine thermodynamic parameters and also detect formation of higher order structures. This article aims to show that CD spectroscopy is an important complementary technique to NMR spectroscopy and X-ray diffraction in quadruplex studies. 相似文献
104.
Proteomic analysis of wheat proteins recognized by IgE antibodies of allergic patients 总被引:1,自引:0,他引:1
Sotkovský P Hubálek M Hernychová L Novák P Havranová M Setinová I Kitanovicová A Fuchs M Stulík J Tucková L 《Proteomics》2008,8(8):1677-1691
Wheat belongs to six major food allergens inducing IgE-mediated hypersensitivity reaction manifesting as cutaneous, gastrointestinal, and respiratory symptoms. Although cereals are a staple food item in most diets, only a few wheat proteins causing hypersensitivity have been identified. To characterize wheat allergens, salt-soluble wheat extracts were separated by 1-DE and 2-DE and IgE-binding proteins were detected by immunoblotting using sera of patients with allergy to ingested wheat. Proteins, frequently recognized by IgE on 2-DE were analyzed by MALDI-TOF and QTOF and their spectrum was completed by 1-DE and LCQ(DECA) nLC-MS/MS IT technique. Using all three techniques we identified 19 potential wheat allergens such as alpha-amylase inhibitors, beta-amylase, profilin, serpin, beta-D-glucan exohydrolase, and 27K protein. Employing newly developed ELISA, levels of IgE Abs against Sulamit wheat extract and alpha-amylase inhibitors type 1 and 3 were quantified and shown to be significantly elevated in sera of allergic patients compared to those of healthy controls. The level of IgE Abs against alpha-amylase inhibitor type 3 was lower, slightly above the cut-off value in the majority of patients' sera. Our findings contribute to the identification of wheat allergens aimed to increase the specificity of serum IgE and cell activation diagnostic assays. 相似文献
105.
Vlková E Rada V Trojanová I Killer J Smehilová M Molatová Z 《Archives of animal nutrition》2008,62(5):359-365
The development of faecal bacteria composition in calves fed milk or a combined diet was investigated from 4 to 21 days of age. On day 7, bifidobacteria in faeces of milk-fed calves already increased from about 7.6 to 9.2 log CFU/g and did not change until the end of the study, whereas in calves fed the combined diet bifidobacteria only moderately increased to 7.9 log CFU/g and decreased slowly until day 21. The counts of bifidobacteria in calves on a combined diet were significantly (p < 0.01) lower compared to those in milk-fed calves. Bifidobacterial counts determined by cultivation or by fluorescence in situ hybridisation (FISH) did not differ significantly. Our results showed that the occurrence of bifidobacteria in calf faeces is highly dependent on the diet composition. Faecal bacteria flora of calves fed exclusively by milk is rich in bifidobacteria, but in calves on a combined diet coliforms dominated. 相似文献
106.
Engl J Ciardi C Tatarczyk T Kaser S Laimer M Laimer E Weiss H Aigner F Molnar C Tilg H Patsch JR Ebenbichler CF 《Obesity (Silver Spring, Md.)》2008,16(8):1838-1842
Objective: Adipocyte fatty acid‐binding protein (A‐FABP) is a plasma biomarker recently associated with the metabolic syndrome. The aim of these studies was to investigate changes of A‐FABP during profound weight loss induced by laparoscopic adjustable gastric banding (LAGB). Methods and Procedures: In study one, 29 severely obese female subjects were examined before and 1 year after surgical treatment. A subgroup of 10 patients was investigated in 3‐month intervals. Metabolic parameters were determined using standard methods, and A‐FABP was detected using a commercially available enzyme‐linked immunosorbent assay. Results: Mean weight loss after 1 year was 24.9 kg (P < 0.001), mainly due to a decrease in fat mass. Metabolic parameters improved substantially. However, serum A‐FABP remained stable. In study two, a subgroup of 10 patients was examined quarterly to determine the time course of A‐FABP changes. Quarterly measurements of serum A‐FABP were significantly higher than baseline levels with the highest A‐FABP value after the first 3 months, where patients had highest weight loss. Discussion: Our results in study one show that A‐FABP serum levels are positively associated with body weight and fat mass. However, 1 year after pronounced weight loss A‐FABP levels remained unchanged. In study two, time course analyses revealed maximum increase of serum A‐FABP in parallel to highest weight loss, which allows to suppose that A‐FABP is not only a biomarker of the metabolic syndrome in the steady state, but also a marker of weight changes in dynamic situations. 相似文献
107.
Previously we described a new member of the Neoparamoeba genus, N. perurans, and showed that it is an agent of amoebic gill disease (AGD) of Atlantic salmon Salmo salar cultured in southeast Tasmania, Australia. Given the broad distribution of cases of AGD, we were interested in extending our studies to epizootics in farmed fish from other sites around the world. Oligonucleotide probes that hybridise with the 18S rRNA of N. perurans, N. branchiphila or N. pemaquidensis were used to examine archival samples of AGD in Tasmania as well as samples obtained from 4 host fish species cultured across 6 countries. In archival samples, N. perurans was the only detectable amoeba, confirming that it has been the predominant aetiological agent of AGD in Tasmania since epizootics were first reported. N. perurans was also the exclusive agent of AGD in 4 host species across 6 countries. Together, these data show that N. perurans is a cosmopolitan agent of AGD and, therefore, of significance to the global mariculture industry. 相似文献
108.
We describe a case of monozygotic (MZ) male twins (14.6 years old) who suffered from a severe form of catatonic schizophrenia. On admission, the principal symptoms of the brothers were stupor, mutism, catatonic posturing, rigidity, negativism, and refusal of food and liquids. They were treated with electroconvulsive therapy (ECT) with no effect (twin A) and almost no effect (twin B). Both twins improved with initiation of olanzapine therapy. Twin B showed a marked improvement by week 2 on a dose of 10 mg daily (qd). Improvement in twin A was seen by week 4 on a dose of 15 mg qd. Twin B was discharged after 8 weeks and twin A after 11 weeks of olanzapine treatment. This appears to be the first report on concordant positive responses to olanzapine in MZ twins with catatonic schizophrenia, as well as, the first report on concordant resistance to ECT. 相似文献
109.
Two protists isolated simultaneously from the same sample of gill tissue of Psetta maxima (L.) were identified as Thecamoeba hilla Schaeffer, 1926 and Labyrinthula sp. A Labyrinthula strain (LTH) derived from a mixed culture of both organisms was well established in a short time, while subcultures of T. hilla continued to be associated with Labyrinthula cells despite all efforts to eliminate them. Ultrastructural examination, repeated several times in the course of long-lasting subculturing of amoebae, revealed that trophozoites of T. hilla host in their cytoplasm multiplying labyrinthulid cells. Comparison of SSU rDNA sequences of the Labyrinthula strain LTH and those from labyrinthulid endosymbionts from T. hilla verified the assumption that the extra- and intra-cellularly multiplying Labyrinthula cells are identical organisms. The association of the marine amoeba T. hilla and Labyrinthula sp. displayed signs of mutualistic symbiosis. 相似文献
110.
Lorenz JN Loreaux EL Dostanic-Larson I Lasko V Schnetzer JR Paul RJ Lingrel JB 《American journal of physiology. Heart and circulatory physiology》2008,295(1):H273-H280
ACTH-induced-hypertension is commonly employed as a model of stress-related hypertension, and despite extensive investigation, the mechanisms underlying elevated blood pressure (BP) are not well understood. We have reported that ACTH treatment increases tail-cuff systolic pressure in wild-type mice but not in mutant mice expressing ouabain-resistant alpha(2)-Na(+)-K(+)-ATPase subunits (alpha2(R/R) mice). Since tail-cuff measurements involve restraint stress, the present study used telemetry to distinguish between an effect of ACTH on resting BP vs. an ACTH-enhanced stress response. We also sought to explore the mechanisms underlying ACTH-induced BP changes in mutant alpha2(R/R) mice vs. wild-type mice (ouabain-sensitive alpha(2)-Na(+)-K(+)-ATPase, alpha2(S/S) mice). Baseline BP was not different between the two genotypes, but after 5 days of ACTH treatment, BP increased in alpha2(S/S) (104.0 +/- 2.6 to 117.7 +/- 3.0 mmHg) but not in alpha2(R/R) mice (108.2 +/- 3.2 to 111.5 +/- 4.0 mmHg). To test the hypothesis that ACTH hypertension is related to inhibition of alpha(2)-Na(+)-K(+)-ATPase on vascular smooth muscle by endogenous cardiotonic steroids, we measured BP and regional blood flow. Results suggest a differential sensitivity of renal, mesenteric, and cerebral circulations to ACTH and that the response depends on the ouabain sensitivity of the alpha(2)-Na(+)-K(+)-ATPase. Baseline cardiac performance was elevated in alpha2(S/S) but not alpha2(R/R) mice. Overall, the data establish that the alpha(2)-Na(+)-K(+)-ATPase ouabain-binding site is of central importance in the development of ACTH-induced hypertension. The mechanism appears to be related to alterations in cardiac performance, and perhaps vascular tone in specific circulations, presumably caused by elevated levels of circulating cardiotonic steroids. 相似文献