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71.
Summary At the Mount Athos the Capercaillie is spread in the montane high forests at an altitude between 1140 m and 1340 m above sea level. This isolated occurrence at the southern boundary of the species area and 140 km to the south of the breeding place in the Rhodope Mountains is the southernmost occurrence recorded so far. In former times, the Capercaillie presumably was widespread in the mountain forests of Central and Northern Greece.  相似文献   
72.
Zusammenfassung In einer intensiv landwirtschaftlich genutzten Fläche des schweizerischen Mittellandes wurden 1983–1987 vier Feldlerchenaggregationen mit maximal 39 Brutpaaren untersucht. Die Tradition (Ortstreue) bestimmte in erster Linie die Revierwahl und das Verteilungsmuster. Die Reviere waren mit ha sehr groß; ihre Größe korrelierte negativ mit der Anzahl Parzellen pro Fläche und der Kulturendiversität. Die Nutzung des Ressourcenangebots (Nistplatz, Nahrung, Schutz) war abhängig von den Fortbewegungsmöglichkeiten. In großparzellig strukturierten Flächen mit geringer Kulturendiversität kam es häufig zu Revierverschiebungen und Reviervergrößerungen. Die Feldlerche versucht, im Laufe der Brutperiode den Getreideanteil im Revier zu verkleinern und Kulturen wie Rüben, Kartoffeln und auch Mais zu aquirieren. Die Nistplatzwahl zeigte eine deutliche Präferenz für alle nicht zu dicht stehenden, grasartigen Kulturen (Weizen, Hafer, Fettwiese). Eine Vegetationshöhe von 15–25 cm und eine Bodenbedeckung von 20–50 % bieten optimale Bedingungen für den Nestbau. 51 % aller Nester wurden in der Fettwiese angelegt, 20 % im Winterweizen und 18 % im Mais. Je nach Bewirtschaftungsart brüteten die im Mittel 2,4–2,8mal pro Brutsaison. Die Schlüpfrate von 220 Gelegen betrug 0,58. 44 % der geschlüpften Jungvögel verließen das Nest. Der Bruterfolg (nestverlassende Junge/gelegte Eier) lag bei max. 25 %. Dem Fütterungsverhalten der Altvögel nach zu schließen, wurden maximal 50 % der nestverlassenden Jungen flügge. Durchschnittlich war mit 0,9 flüggen Jungen pro Brutpaar und Jahr zu rechnen. Brutverluste waren kulturspezifisch und daher in erster Linie vom Neststandort abhängig.
Territoriality and breeding biology of Skylark (Alauda arvensis) in an intensively farmed area in Switzerland
Summary In 1983–1987 four plots (total surface 307 ha) with up to 39 breeding pairs were studied in an area of intensive cultivation in the Swiss Lowlands (390 m asl). Distribution pattern and selection of territories are determined by a strong site tenacity of the birds. The size of territories averaged 3,3±0,9 hectares. It correlates negatively with the number of different crops per unit area and the diversity of cultures.The mobility within the vegetation determined which types of farmland ressources may be used for nesting, feeding and cover. Shifts of territories and attempts to enlarge them were frequent in areas of large plots with low crop diversity. During the season, Skylarks tried to reduce the proportion of cereal fields within their territory and to gain plots planted with sugar-beet, potatoes and corn.Their choice of nesting sites showed a strong preference for less dense grass crops such as wheat, oat or meadows. Optimal conditions for nest sites were in fields with a vegetation height of 15–25 cm and a ground coverage of 20–50 %. 51 % of 220 nests were constructed in heavily manured meadows, 20 % in winter wheat fields and 18 % in corn fields. Females bred on average 2,4–2,8 times per breeding season, depending on the type of cultivation (agriculture, husbandry). Hatching rate was 58 % out of 220 clutches, and 44 % of the hatched young left the nest. Maximum breeding success (i. e. young birds leaving the nest/number of eggs laid) was thus maximal 25 %. Observations of parental feeding behaviour suggest that a maximum of 50 % of the young larks which leave the nests survive to the age of fledging. It is estimated that 0,9 fledglings are raised per breeding pairs and year. Losses of broods vary according to farming practises in the different crops and therefore are largely depending on nesting sites.
  相似文献   
73.
l-Ascorbate is taken up into brush border vesicles from kidney cortex of rat, rabbit and guinea pig by an efficient, Na+-dependent and potential-sensitive transport process. This uptake shows saturation (Km:0.1–0.3 mM) and is strongly stimulated by low concentrations of N3?. Erythorbate (d-isoascorbate) seems to be another, but poorer, substrate of the same transporter.  相似文献   
74.
Degradation of 4-chlorophenylacetic acid by a Pseudomonas species.   总被引:6,自引:3,他引:3       下载免费PDF全文
Pseudomonas sp. strain CBS3 was able to utilize 4-chlorophenylacetic acid as the sole source of carbon and energy. When this strain was grown with 4-chlorophenylacetic acid, homoprotocatechuic acid was found to be an intermediate which was further metabolized by the meta-cleavage pathway. Furthermore, three isomers of chlorohydroxyphenylacetic acid, two of them identified as 3-chloro-4-hydroxyphenylacetic acid and 4-chloro-3-hydroxyphenylacetic acid, were isolated from the culture medium. 4-Hydroxyphenylacetic acid was catabolized in a different manner by the glutathione-dependent homogentisate pathway. Degradation enzymes of both of these pathways were inducible.  相似文献   
75.
For fluorescence labelling intact cells and isolated cell envelopes (membranes) from Salmonella typhimurium and Acholeplasma laidlawii were treated with mixed dansylchloride-lecithin-cholesterol vesicles. This kind of dansylation, which has been supposed to be specific for cell surface proteins, produced fluorescent protein pattern after SDS-polyacrylamide gel electrophoresis only when isolated envelopes were dansylated. Acid hydrolysis of fluorescent cell envelopes of Salmonella typhimurium yielded O-dansyltryosine and epsilon-N-dansyl-lysine besides the free sulfonic acid and unidentified compounds. However, no fluorescent proteins were detectable in cell envelopes isolated from dansylated intact bacteria from Salmonella typhimurium. In accord Acholeplasma laidlawii showed only fluorescence from proteins with a molecular weight higher than 100000.  相似文献   
76.
77.
Bleich M  Shan QX 《生理学报》2007,59(4):443-453
K^+通道在上皮细胞内以极化的方式表达,形成一个庞大的膜蛋白家族。出于对主要依赖Na^+-K^+-ATPase而维持的细胞内跨膜K^+梯度的考虑,K^+通道在跨上皮细胞转运中的主要作用为:膜电位生成和K^+循环。本文以肾近端小管和胃壁上皮细胞转运为例简要阐述了K^+通道的作用。在这两个组织中,K^+通道活性限速跨上皮细胞转运,调节细胞体积。近年来,药理学工具和转基因动物的实验证实了对K^+通道的原先认知,并将研究深入到分子水平。K^+通道的分子结构挑战高亲和力药物分子的设计,及其多组织同时表达的两个典型特征阻碍了高活性、组织特异性小分子治疗的进展。然而,抑制K^+通道能阻断胃酸分泌等病理生理机制的深入研究,促进K^+通道药物用于胃病治疗和作为肾脏转运抑制剂用于肾脏相关疾病治疗。  相似文献   
78.
Gap junctions (GJ) are important determinants of cardiac conduction and the evidence has recently emerged that altered distribution of these junctions and changes in the expression of their constituent connexins (Cx) may lead to abnormal coupling between cardiomyocytes and likely contribute to arrhythmogenesis. However, it is largely unknown whether changes in the expression and distribution of the major cardiac GJ protein, Cx43, is a general feature of diverse chronic myocardial diseases or is confined to some particular pathophysiological settings. In the present study, we therefore set out to investigate qualitatively and quantitatively the distribution and expression of Cx43 in normal human myocardium and in patients with dilated (DCM), ischemic (ICM), and inflammatory cardiomyopathies (MYO). Left ventricular tissue samples were obtained at the time of cardiac transplantation and investigated with immunoconfocal and electron microscopy. As compared with the control group, Cx43 labeling in myocytes bordering regions of healed myocardial infarction (ICM), small areas of replacement fibrosis (DCM) and myocardial inflammation (MYO) was found to be highly disrupted instead of being confined to the intercalated discs. In all groups, myocardium distant from these regions showed an apparently normal Cx43 distribution at the intercalated discs. Quantitative immunoconfocal analyis of Cx43 in the latter myocytes revealed that the Cx43 area per myocyte area or per myocyte volume is significantly decreased by respectively 30 and 55% in DCM, 23 and 48% in ICM, and by 21 and 40% in MYO as compared with normal human myocardium. In conclusion, focal disorganization of GJ distribution and down-regulation of Cx43 are typical features of myocardial remodeling that may play an important role in the development of an arrhythmogenic substrate in human cardiomyopathies.  相似文献   
79.
We have previously reported the existence of a polymorphism that causes black populations to have lower mean RBC galactokinase activity than comparable white populations. We have designated this allele the Philadelphia variant, GALKP, and have suggested that it is common in blacks and rare in whites. GALKP individuals have normal WBC GALK activity, in contrast to the half normal WBC GALK activities of heterozygotes for the allele (GALKG) that causes the galactokinase-deficient form of galactosemia. In one family, we have presented evidence for the existence of two sisters heterozygous for both GALKG and GALKP alleles. These individuals have 50% normal WBC GALK activity and less than 50% normal red cell activity. The latter finding indicates that the two variant GALK alleles additively affect RBC activity. The WBC results suggest that the low activity of GALK in RBC of individuals with the GALKP allele is due to its relative instability. We could obtain no evidence for such instability from studies of high reticulocyte bloods or RBC fractionation. Furthermore, we could not demonstrate that the GALK in WBC from GALKP individuals has altered electrophoretic migration.  相似文献   
80.
It has been argued that the limited genetic diversity and reduced allelic heterogeneity observed in isolated founder populations facilitates discovery of loci contributing to both Mendelian and complex disease. A strong founder effect, severe isolation, and substantial inbreeding have dramatically reduced genetic diversity in natives from the island of Kosrae, Federated States of Micronesia, who exhibit a high prevalence of obesity and other metabolic disorders. We hypothesized that genetic drift and possibly natural selection on Kosrae might have increased the frequency of previously rare genetic variants with relatively large effects, making these alleles readily detectable in genome-wide association analysis. However, mapping in large, inbred cohorts introduces analytic challenges, as extensive relatedness between subjects violates the assumptions of independence upon which traditional association test statistics are based. We performed genome-wide association analysis for 15 quantitative traits in 2,906 members of the Kosrae population, using novel approaches to manage the extreme relatedness in the sample. As positive controls, we observe association to known loci for plasma cholesterol, triglycerides, and C-reactive protein and to a compelling candidate loci for thyroid stimulating hormone and fasting plasma glucose. We show that our study is well powered to detect common alleles explaining ≥5% phenotypic variance. However, no such large effects were observed with genome-wide significance, arguing that even in such a severely inbred population, common alleles typically have modest effects. Finally, we show that a majority of common variants discovered in Caucasians have indistinguishable effect sizes on Kosrae, despite the major differences in population genetics and environment.  相似文献   
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