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51.
van der Sluis C Westerink BH Dijkstal MM Castelein SJ van Boxtel AJ Giuseppin ML Tramper J Wijffels RH 《Biotechnology and bioengineering》2001,75(3):267-275
Steady-state culture characteristics are usually determined in chemostat cultivations, which are very time-consuming. In contrast, acceleration-stat (A-stat) cultivations in which the dilution rate is continuously changed with a constant acceleration rate are not so time-consuming, especially at high acceleration rates. Therefore, the A-stat could be advantageous to use instead of the chemostat. However, the highest acceleration rate, meaning the fastest A-stat that can be applied for estimating steady-state culture characteristics, is not known yet. Experimental results obtained with Zygosaccharomyces rouxii, an important yeast in soy sauce processes, showed that the culture characteristics during the A-stat with an acceleration rate of 0.001 h(-2) were roughly comparable to those of the chemostat. For higher acceleration rates the deviation between the culture characteristics in the A-stat and those in the chemostat obtained at the same dilution rate generally started to increase. The source of these deviations was examined by simulation for Saccharomyces cerevisiae. The simulations demonstrated that this deviation was not only dependent on the metabolic adaptation rate of the yeast, but also on the rate of change in environmental substrate concentrations during A-stats. From this work, it was concluded that an A-stat with an acceleration rate of 0.001 h(-2) is attractive to be used instead of chemostat whenever a rough estimation of steady-state culture characteristics is acceptable. 相似文献
52.
A new genus and species of troglobitic buthid scorpion are described on the basis of a single specimen collected in Brazil. This is the first cavernicolous scorpion ever found in Brazil, and only the second to be found in South America. Some considerations on troglobitic scorpions are proposed. 相似文献
53.
Karina Matilla 《L'Anthropologie》2003,107(1):49-115
The Marcel Clouet Cave in Cognac (Charente) is a small cavity, more a shelter than a true cave, in the Cretaceous limestone cliffs along the Antenne, a tributary of the Charente River. The site suffered from a number of clandestine excavations before the work of C. Burnez, who was then followed by one of us (A.D.). The material recovered in stratigraphic context represents both Middle and Upper Paleolithic. The former is an example of Mousterian of Acheulian Tradition (MTA), while the latter includes Aurignacian (probably early) and Perigordian (probably Châtelperronian Gravettian), as well as some Solutrean objects recovered outside of stratigraphic context. It is important to note that this is one of only a few Charentian rockshelter sites, which has yielded an example of MTA. 相似文献
54.
Rodrigo de Balbín Behrmann J.Javier Alcolea GonzálezM. Ángel González Pereda A. Moure Romanillo 《L'Anthropologie》2002,106(4):565
During the year 2002 we have continued the works in the massive of Ardines at Ribadesella, Asturias, and especially in its fundamental cave, Tito Bustillo. Here the prospection has permitted us to find several new elements of great cultural and graphic value. A consistent deposit in four cutted contours in the form of head of hind and also two new galleries, called gallery of the Bisons and gallery of the Anthropomorphes, communicated with the Principal Gallery of the cave and mutually. In this last one exist remains of adaptation of the space, bony remains that we are yet digging and two figures of painted anthropomorphes with an exceptional interest. Finally, in the ensemble N XI, place where it is found the habitation deposit, and where we have found large masses of red colourings prepared for its use, exists a small final cave, where also it has been painted in its interior, and where the mouth is opened among the remains of a great deposit in surface that occupies all its northern part. 相似文献
55.
The application of sieving techniques to bulk samples from the Ashizawa Formation, Futaba Group (Lower Coniacian) of northeastern
Honshu, Japan, has yielded well-preserved mesofossil assemblages comparable with those recently described from eastern North
America, Europe, and central Asia. Among the most abundant and distinctive components of these assemblages are fusiform fruits
that are assigned here to a new genus and species, Hironoia fusiformis gen. et sp. nov. The fruits developed from an epigynous ovary with three to four locules. Each locule bears one seed and
has a distinctive dorsal germination valve. These features of the fruit, along with the adnate calyx, indicate an affinity
to extant Cornales and specifically the Cornaceae sensu lato. The recognition of an unequivocal cornalean fruit in the Early
Coniacian–Early Santonian of Japan provides the earliest record of this group in the fossil record. It also establishes a
minimum age for the early divergence of the asterid clade, a major group of living angiosperms comprising more than a third
of all species of extant flowering plants.
Electronic Publication 相似文献
56.
Molecular recognition between 4aS/R-galanthamine diastereoisomers (1: 4aS-galanthamine; 2: 4aR-galanthamine) and -cyclodextrin (-CD) were studied by use of docking and molecular dynamics (MD) simulation approaches. The binding energy of constructed 2···-CD complexes is ~17 kcal mol–1 lower than that of 1···-CD, implying a stronger binding ability of 2 with -CD than that of 1. The theoretical modeling result is consistent with our previous CZE result, which demonstrated that -CD is an efficient chiral additive for separating 1 and 2. The modeling result also indicates that both hydrophobic interaction and H-bond force may work as major factors for molecular recognition between the galanthamine diastereoisomers and -CD.
Figure Chemical structures of 4aS-galanthamine (left) and 4aR-galanthamine (right)Abbreviations Galanthamine
4aS,6R,8aS-4a,5,9,10,11,12-Hexahydroxy-3-methoxy-11-methyl-6H-benzofuro[3a,3,2-e,f]benzazepin-6-ol 相似文献
57.
本文记述了采自湖北省神农架的平头反颚虽蜂属EudinostigmaTobias一新种:长角反颚茧蜂E.longusWuetChen。该新种触角甚长,24节;盾纵沟前瑞明显,具1深的椭园形中陷,腹板侧沟具刻痕,并胸腹节具中纵肯和叉脊,无小室;后足腿节粗状,长为宽的3.6倍;腹柄节长为端宽的1.7倍。新种模式标本保存于福建农业大学益虫室。 相似文献
58.
Abstract. This paper deals with the spatial distribution pattern of the bird-dispersed plant Daphne gnidium in a 10-yr abandoned field under Mediterranean conditions. Colonization of Mediterranean old-fields by bird-dispersed plants is expected to fit a theoretical model in which (1) seed dispersal follows a negative exponential curve with the distance from the seed source and (2) seedlings are better established under perches (nucleation sensu Yarranton & Morrison 1974). However, post-dispersal processes such as seed predation, seed germination and seedling establishment are also spatial-dependent and can lead to spatial autocorrelation in the seedling distribution within an old-field. Results show that both processes in the model (curve of seed dispersal and nucleation) significantly explained the spatial distribution of the seedlings, but some spatial variance remained unexplained. The semivariogram with the statistical residuals of the model detected spatial dependence at small (< 20 m) and large (> 250 m) distance intervals, indicating that some mechanisms with spatial components, apart from the curve of seed dispersal and nucleation under perches, also determined the distribution of seedlings colonizing fields. At scales below 20-m intervals, semivariance increased indicating that similarity between plots is lost when distance increases between them. This pattern may be explained because the favourable micro-environmental conditions for establishment produced under perches could be extended towards neighbour plots where perches were absent. A flat semi-variogram between 20-m and 250-m intervals shows spatial independence along this range. From 250 m on, the semivariance increased again, indicating spatial dependence at coarse-scale. It is possible that the colonization model failed at this scale because different spatial processes to those included in the model (perch presence and distance to the shrubland) could be controlling seed colonization at coarse-scale. 相似文献
59.
Potential replacement vegetation: an approach to vegetation mapping of cultural landscapes 总被引:1,自引:0,他引:1
Milan Chytrý 《应用植被学》1998,1(2):177-188
Abstract. The concept of mapping potential replacement vegetation (PRV) is proposed as a parallel to potential natural vegetation (PNV). Potential replacement vegetation (PRV) is an abstract and hypothetical vegetation which is in balance with climatic and soil factors currently affecting a given habitat, with environmental factors influencing the habitat from outside such as air pollution, and with an abstract anthropogenic influence (management) of given type, frequency and intensity. For every habitat, there is a series of possible PRV-types corresponding to the different anthropogenic influences, e.g. grazing, mowing, trampling or growing cereals. The PRV-concept is especially useful in large-scale mapping (scales > 1 : 25 000) of small areas where replacement vegetation is the focus of attention for managers and land-use planners, for example in nature reserves where the aim is conservation of replacement vegetation managed in a traditional way, or in restoration ecology where the concept may be used for defining restoration goals and evaluating the success of restoration efforts. At smaller scales, PRV-mapping may be useful for revealing the biogeographical patterns of larger areas which may be different from the corresponding PNV patterns, because replacement vegetation and natural vegetation may respond to environmental gradients at different scales. An example of medium-scale PRV-mapping through the coincidence of diagnostic species of vegetation types, based on species distribution grid data, is presented. In cultural landscapes, the advantage of using the PRV-concept instead of PNV is its direct relationship to the replacement vegetation. In the habitat mapping with respect to the replacement vegetation, the PRV concept yields more valuable results than the mapping of actual vegetation, as the latter is strongly affected by spatially variable anthropogenic influences which may be largely independent from climatic and soil factors. 相似文献
60.