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51.
Near infrared spectroscopy is used clinically to investigate patterns of change in cerebral oxygenation. We have shown that differences reported between authors are likely the result of computer encoding errors in the manipulation of matrices. Current methods compute the inverse of a non-square matrix to derive chromophore concentration values, and solution of another non-square matrix to derive polynomial coefficients of a least squares best fit curve from which the first derivative can be used to estimate blood flow values. Encoding of these pseudo inverses involves too many nested looping steps to easily identify encoding errors. We have given C/C++ source code along with sample numerical values at the termination of each loop within the algorithm. This provides counter checking for future software development by other programmers, and also permits other investigators to report whether the software used for their experiments agrees with previously published material. 相似文献
52.
Ecdysial cleavage lines of acariform mites (Arachnida, Acari) 总被引:1,自引:0,他引:1
Among mites the ancestral ecdysial cleavage line, or line of dehiscence (a), is inferred by outgroup comparison to be prodehiscent: U-shaped, passing around the front of the mite just above the insertions of the appendages, such that the mite ecloses anteriorly. From preserved and living individuals and exuviae, we found prodehiscence (or its slight variations) to be widespread in Acariformes. It appears to be pervasive in endeostigmatic mites, eupodine Prostigmata, and basal taxa in the Oribatida (Enarthronota, Palaeosomata); it is dominant in cleutherengone Prostigmata and is present in at least one anystine family (Caeculidae). Three general modes of dehiscence are considered to be derived within acariform mites. (1) Merodehiscence is a transverse splitting of the dorsal cuticle at or near the juncture of proterosoma and hysterosoma; it evolved separately in thrcc groups of Prostigmata (Tetranychidae, an undefined subgroup within Cheylctidae, and active instars of Parasitengona) and in a genus of Astigmata (Histiogaster). (2) Trarnsdehiscence is a transverse splitting of the dorsal hysterosomal cuticle anterior to the opisthosomal glands; it occurs in middle-derivative oribatid mites (the paraphyletic Desmonomata), and new observations show it to be widespread in Astigmata, lending support to the hypothesis that the latter group evolved from within Desmonomata. (3) Circumdehiscence is a circumferential splitting of the hysterosomal cuticle that may be incomplete anteriorly; it has long been known to characterize the monophyletic oribatid taxon Brachypylina, but it is convergent with a similar dehiscence in an unrelated family, Lohmanniidae. Transdehiscent and circumdehiscent mites eclose posteriorly. Astigmata exhibit the greatest variety of modes of dehiscence, including the three derived modes and a probable reversal to prodehiscence in Algophagidae. Furthermore, heteromorphic deutonymphs (hypopi) may ecdyse differently from other immature instars of the same species. 相似文献
53.
D. GOTTELLI C. SILLERO-ZUBIRI† G. D. APPLEBAUM‡ M. S. ROY D. J. GIRMAN‡ J. GARCIA-MORENO‡ E. A. OSTRANDER§ R. K. WAYNE ‡ 《Molecular ecology》1994,3(4):301-312
The world's most endangered canid is the Ethiopian wolf Canis simensis , which is found in six isolated areas of the Ethiopian highlands with a total population of no more than 500 individuals. Ethiopian wolf populations are declining due to habitat loss and extermination by humans. Moreover, in at least one population, Ethiopian wolves are sympatric with domestic dogs, which may hybridize with them, compete for food, and act as disease vectors. Using molecular techniques, we address four questions concerning Ethiopian wolves that have conservation implications. First, we determine the relationships of Ethiopian wolves to other wolf-like canids by phylogenetic analysis of 2001 base pairs of mitochondrial DNA (mtDNA) sequence. Our results suggest that the Ethiopian wolf is a distinct species more closely related to gray wolves and coyotes than to any African canid. The mtDNA sequence similarity with gray wolves implies that the Ethiopian wolf may hybridize with domestic dogs, a recent derivative of the gray wolf. We examine this possibility through mtDNA restriction fragment analysis and analysis of nine microsatellite loci in populations of Ethiopian wolves. The results imply that hybridization has occurred between female Ethiopian wolves and male domestic dogs in one population. Finally, we assess levels of variability within and between two Ethiopian wolf populations. Although these closely situated populations are not differentiated, the level of variability in both is low, suggesting long-term effective population sizes of less than a few hundred individuals. We recommend immediate captive breeding of Ethiopian wolves to protect their gene pool from dilution and further loss of genetic variability. 相似文献
54.
DONALD W. DUSZYNSKI SHIRLEY A. ROY GILBERT A. CASTRO 《The Journal of eukaryotic microbiology》1978,25(2):226-231
SYNOPSIS Experiments were designed to study intestinal pathophysiologic changes associated with coccidial infections in mammalian hosts. Pairs of male Sprague-Dawley rats were killed at various times postinoculation (PI) with 104 or 106 sporulated occysts of Eimeria nieschulzi. The small intestine from each rat was removed, weighed, measured, and divided into thirds. From the middle 11 cm of each third, one cm was fixed for histologic examination. Mucosa was scraped from the remaining 10 cm and was assayed for protein content and for peroxidase, sucrase and trehalase activities. Infection with E. nieschulzi was associated with increased mass of the small bowel. Histologically, crypt depth throughout the small bowel was significantly greater (P≤ 0.005) in infected rats than in non-infected ones on PI days 8 and 16. Villus height did not change drastically during low-dose infections (104 oocysts) and varied during high-dose infections (106 oocysts). As a result of these morphologic changes in the mucosa, crypt/villus ratios were usually significantly greater (P≤ 0.005) in all infected rats throughout the small bowel. In general, increased gut weight and changes in crypt and villus dimensions became evident by PI day 2, were most pronounced at PI day 8, and began to return to control values by PI day 16. Peroxidase, sucrase, and trehalase levels equaled or were slightly higher than in controls on PI day 2, dropped significantly below controls (P≤ 0.05) by PI day 8, and returned to, or exceeded control levels by PI day 16. The intensity of all changes was directly dose-dependent. 相似文献
55.
Cut twigs of Monterey pine(Pinus radiata D.Don) were banded with a 14C labelled morphactin formulation and the lower half of the twig placed in a Scholander type pressure bomb. Water was pumped through the twig from a reservoir inside the bomb and exudate collected from the protruding end of the twig. Using this method it was possible to determine that the slowest step in the translocation of morphactin was the passage across the outer layer of bark. Subsequent passage through the twig was not affected by girdling the bark suggesting that morphactin was translocated upwards via the xylem. The 14C compound in the exudate from live twigs differed from morphactin and was tentatively identified as the carboxylic acid derivative of the morphactin ester. The cut twig system facilitated studies on the uptake, metabolism and translocation of morphactin and should prove useful for studying the uptake and fate of other chemicals considered for bark application to trees. 相似文献
56.
An iron oxidizing strain of Thiobacillus ferrooxidans has been grown on solid medium using purified agar, carrageenan (Type 1) and agarose. This strain produces isolated and transferable colonies after 7 d incubation. Growth (increase in viable cells) by the direct plating method has been followed in relation to iron oxidation. Acidity, agar concentration and phosphate influenced colony development on solid medium. 相似文献
57.
Leaf structure and chemical composition as affected by elevated CO2 : genotypic responses of two perennial grasses 总被引:2,自引:2,他引:0
Genotypic variability was studied in two Mediterranean grass species, Bromus erectus and Dactylis glomerata , with regard to the response to CO2 of leaf total non-structural carbohydrate concentration ([TNC]lf ), specific leaf area (SLA), and leaf carbon and nitrogen concentrations ([C]lf and [N]lf , respectively). Fourteen genotypes of each species were grown together on intact soil monoliths at ambient and elevated CO2 concentrations (350 and 700 μmol mol−1 , respectively). In both species, the most consistent effect of elevated CO2 was an increase in [TNC]lf and a decrease in leaf nitrogen concentration when expressed either as total dry mass [Nm ]lf , structural dry mass [Nm st]lf or leaf area [Na ]lf . The SLA decreased only in D. glomerata , due to an accumulation of total non-structural carbohydrates and to an increase in leaf density. No genotypic variability was found for any variable in B. erectus , suggesting that genotypes responded in a similar way to elevated CO2 . In D. glomerata , a genotypic variability was found only for [Cst], [Nm ]lf , [Nm st]lf and [Na ]lf . Since [Nm ]lf is related to plant growth and is a strong determinant of plant–herbivore interactions, our results suggest evolutionary consequences of elevated CO2 through competitive interactions or herbivory. 相似文献
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