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901.
Synopsis To better understand patterns of fish assemblage composition in Wisconsin streams in relation to major environmental gradients, I carried out multivariate direct gradient analysis (canonical correspondence analysis) of two large independent datasets on fish species abundance in Wisconsin streams. Analysis of the two datasets yielded similar results, suggesting that observed patterns and relationships were real. Stream sites were distributed along fish species-environment gradients, but segregation into distinct stream temperature and geographic groups was also evident. The strongest gradient in both datasets was related to summer water temperature patterns, and encompassed a transition from small, coldwater streams dominated by salmonids, cottids, certain cyprinids, and few other species, to both small and large, warmwater streams dominated by a high diversity of different cyprinids, catostomids, ictalurids, centrarchids, and percids. A second gradient in both datasets was complex but largely geographic. Within it, sites from each of the four ecoregions that occupy Wisconsin formed fairly discrete groups. The strongest differences were between sites in the two southern Wisconsin ecoregions, the Driftless Area and the Southeastern Wisconsin Till Plains, that were dominated by certain cyprinids, ictalurids, and centrarchids, and sites in the two northern Wisconsin ecoregions, the North Central Hardwood Forests and the Northern Lakes and Forests, that were dominated by a different set of cyprinids and ictalurids, plus some petromyzontids, salmonids, catostomids, and percids. Sites from the Driftless Area that were mostly higher-gradient (steep stream slope) and had many riffle-dwelling species could also be distinguished from sites in the Southeastern Wisconsin Till Plains that were mostly lower-gradient and had many pool-dwelling species. The patterns of fish assemblage composition among sites and the associated fish species-environment relationships that were revealed by the analyses provided a framework for developing an ecologically meaningful hierarchical classification of Wisconsin stream sites based on stream thermal regime, ecoregion, stream size, and stream gradient.  相似文献   
902.
Phytopak     
PHYTOPAK, a series of computer programs that facilitates the handling and analysis of large sets of phytosociological data is described. The programs are written in FORTRAN IV, and have been implemented on both IBM and CDC computers. The programs have been developed for use in the National Vegetation Classification, currently being undertaken in Britain, where a requirement for handling very large data-sets (up to 35 000 relevés with a total of over 3000 species represented) was the major requirement.The work described here forms part of the National Vegetation Classification supported by the Nature Conservancy Council. The financial support of J. P. H. by this project is gratefully acknowledged. We are particularly grateful to the University of Cambridge Computing Service for providing computing facilities and friendly advice. The conversion of the IBM version of PHYTOPAK into a CDC version was implemented by B.H. at the University of Manchester Regional Computer Centre, with the assistance of Mr. Cliff Stone. Dr. A. J. C. Malloch kindly provided us with his program for renumbering species code numbers which formed the basis of RENUM. We are grateful to Dr. P. Adam, Dr. M. P. Austin, Dr. M. B. Dale, and Mr. M. O. Hill for helpful comments and suggestions.  相似文献   
903.
904.
Summary

The Atlantic Oakwoods can be seen as ‘at the edge’ in two ways. First, they lie at the extreme oceanic end of a series of Quercus robur and Q. petraea woodlands which stretches eastwards from the North Atlantic coast to the continental heartland of Europe. Second, they are at the northern limit of a range of oceanic oakwoods which extends southwards to Iberia where Q. pyrenaica is an important canopy companion. This paper outlines the main variations in trees, shrubs, herbs and cryptogams that can be seen along these two climatic gradients, so as to highlight what is truly distinctive about the Atlantic Oakwoods and how we might rightly value them.  相似文献   
905.
Abstract. A phytosociological survey of the tundra vegetation of the Kola Peninsula, Russia according to the Braun-Blanquet approach is presented. The areas examined comprise the treeless zones along the shores of the White Sea and the Barents Sea as well as mountain areas above the timberline. Plant communities were assigned to five alliances: Loiseleurio-Diapension on dry, wind-swept habitats on summits and wind-eroded sites in the lowland; Phyllodoco-Vaccinion myrtilli on well-drained soils with intermediate snow cover and moisture status, mostly in the lowlands and lower belts of mountain tundra; Nardo-Caricion bigelowii comprising early snowbed and Salicion herbaceae late snowbed communities; Adenostylion alliariae comprising mesophilous tall-herb communities along mountain springs and in wind-protected and well-drained sites near the sea shore. A DCA-ordination showed that two major gradients determine the varation in tundra vegetation, altitude and topography, which are connected to variation in snow cover. The syntaxa described are well-differentiated, although they form a syntaxonomical continuum.  相似文献   
906.
ObjectiveTo examine whether parathyroid hormone (PTH) is associated with mortality among U.S. adults.MethodsThis study included 8286 U.S. adults aged ≥20 years with a measurement of serum intact PTH from the National Health and Nutrition Examination Survey 2003-2006 linked to national mortality data through 2015. Multivariable Cox proportional hazard regression models were employed to estimate the adjusted hazard ratio (aHR) of all-cause and cause-specific (cardiovascular and cancer) mortality according to intact PTH levels (low or low-normal, <38; middle-normal, 38-56; high-normal, 57-74; high, >74 pg/mL). We also stratified the analyses by serum albumin-adjusted calcium and 25-hydroxy vitamin D (25OHD) levels.ResultsDuring a median follow-up of 10.1 years, the mean age was 49 years, and 48% were men. After adjusting for potential confounders, both the high-normal and high PTH groups showed higher risks of all-cause mortality than the low or low-normal PTH group (high-normal PTH, aHR, 1.28; 95% confidence interval [CI], 1.10-1.48; high PTH, aHR, 1.42; 95% CI, 1.19-1.69]. When stratified by calcium and 25OHD levels, the association between high PTH and mortality was also found among participants with albumin-adjusted calcium levels of ≥9.6 mg/dL (aHR, 1.53; 95% CI, 1.17-2.01) and those with 25OHD levels of ≥20 ng/mL (aHR, 1.46, 95% CI, 1.17-1.82). We found no evidence of the increased cause-specific mortality risks in the high PTH group.ConclusionHigher PTH levels were associated with an increased risk of all-cause mortality, particularly among participants with albumin-adjusted calcium levels of ≥9.6 mg/dL or 25OHD levels of ≥20 ng/mL.  相似文献   
907.
Ultrasound (US) is an inexpensive and non-invasive technique for capturing the image of the thyroid gland and nearby tissue. The classification and detection of thyroid disorders is still in its infant stage. This study aims to present a new thyroid diagnosis approach, which consists of three phases like “(i) feature extraction, (ii) feature dimensionality reduction, and (iii) classification”. Initially, the thyroid images as well as its related data are given as input. From the input image, the features such as“ Grey Level Co-occurrence Matrix(GLCM), Grey level Run Length Matrix(GLRM), proposed Local Binary Pattern(LBP), and Local Tetra Patterns (LTrP)” are extracted. Meanwhile, from the input data, the higher-order statistical features like skewness, kurtosis, entropy, as well as moment get retrieved. Consequently, the Linear Discriminant Analysis (LDA) based dimensionality reduction is processed to resolve the problem of “curse of dimensionality”. Finally, the classification is carried out via two phases: Image features are classified using an ensemble classifier that includes Support Vector Machine (SVM)& Neural Network(NN) models. The data features are subjected to Recurrent Neural Network(RNN) based classification, which is optimized by an Adaptive Elephant Herding Algorithm (AEHO) via tuning the optimal weight. At last, the performance of the adopted scheme is compared to the extant models in terms of various measures. Especially, the mean value of the suggested RNN + AEHO model is 4.35%, 3.54%, 6.07%, 3.8%, 1.69%, 2.85%, 2.07%, 2.54%, 0.13%, 0.035%, and 8.53% better than the existing CNN, NB, RF, KNN, Levenberg, RNN + EHO, RNN + FF, RNN + WOA, WF-CS, FU-SLnO and HFBO methods respectively.  相似文献   
908.
 We assessed the genetic relationships between members of the Fagaceae family by RAPDs in order to better ascertain the taxonomic status of a very particular population of Fagus sylvatica, the ‘tortuosa’ variety. Intra- and inter-population Nei and Li’s mean genetic distances were compared, and the genetic relationships between individuals were clarified on dendrograms by the Neighbor joining method. RAPD analysis was first conducted on three species from three genera, Quercus petraea, Castanea sativa, and Fagus sylvatica, in order to develop an efficient RAPD protocol. The variety level was then studied, and a general tendency of the individuals to cluster by variety was observed. Individuals also clustered by geographic locations, but the genetic distances between populations were not correlated to the distances between sites. Finally, we compared the common beech and ‘tortuosa’ varieties from two different locations, Verzy and Süntel. Both populations from one location were closer than the same variety from two sites. This last result is in agreement with those previously obtained with isozymes. Hypotheses concerning the origin of the ‘tortuosa’ variety are discussed. Received: 9 January 1998 / Accepted: 25 February 1998  相似文献   
909.
Abstract 16S rDNA sequence data was obtained for 11 species of Arthrobacter and 4 species of Micrococcus and compared with that from other members of the arthrobacterial lineage within the order Actinomycetales . The intermixing of members of these two genera and the placement of Renibacterium salmoninarum within the radiation of these two genera, as previously suggested by 16S rRNA cataloguing, is confirmed. The branching pattern reveals several closely related organisms that cluster around the type species of Arthrobacter and Micrococcus ; these species are considered 'core organisms'. A few species, however, branch outside the radiation of core organisms; these include Micrococcus kristinae, Micrococcus halophilus , and, as previously indicated, Micrococcus sedentarius and M. nishinomiyaensis . As phenotypic data that would support the exclusion of these four species from the genus Micrococcus are still lacking taxonomic conclusions should await more thorough comparative studies.  相似文献   
910.
Aim of the study5-Fluorouracil (5-FU) can’t be given orally because of very low bioavailability and produces serious adverse effects. Therefore, the main objective of this research is to develop, evaluate, and comparative effects by different nanoformulations of topical application on chemoprevention of skin cancer in different types of skin.Material and methodsCastor oil (oil), Transcutol HP (surfactant), and Polyethylene glycol (PEG)–400 (co-surfactant) have taken on the basis of nonionic property and highest nanoemulsion (NE)-region. Aqueous micro titration method with ultra-sonication method (based on high energy) was used for the preparation of 5-FU-NE. Optimized-5-FU-NE was stable thermodynamically, and their characterizations was performed on the basis of globule size, zeta potential, refractive index, and viscosity. Optimized-NE has been converted into 5-FU-NE-Gel with the help of Carbopol® 934 and also performed their permeation studies in the different skins (cow, goat, and rat, ex vivo) using Logan transdermal diffusion cell (DHC-6T). Optimized-5-FU-NE and 5-FU-NE-Gel were evaluated cytotoxic studies (in vitro) on the melanoma cell lines.ResultsThe permeation of 5-FU from 5-FU-NE-Gel nanoformulation for rat skin model was 1.56 times higher than the 5-FU-NE and 12.51 times higher than the 5-FU-S for the cow and goat skin model. The values of steady state flux and permeability coefficient for 5-FU-NE-Gel of rat skin were higher i.e. 12.0244 ± 1.12 µgcm−2h−1 and 1.2024 ± 0.073 × 10−2 µg cm−2h−1, respectively. Optimized-5-FU-NE and 5-FU-NE-Gel nanoformulation were found to be physically stable. SK-MEL-5 cancer cells have showed the results based on cytotoxicity studies (in vitro) that 5-FU as Optimized-5-FU-NE-Gel is much more efficacious than 5-FU-NE followed by free 5-FU. Localization of 5-FU from 5-FU-NE-Gel was higher with higher permeation in rat skin.Conclusion5-FU-NE-Gel is found to be for the better to treatment of cutaneous malignancies. It can be developed 5-FU-NE-Gel could be a promising vehicle for the skin cancer chemoprevention.  相似文献   
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