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311.
Correlation of Growth Inhibition Patterns to Nucleoside Transport Models in Neurospora crassa 总被引:3,自引:3,他引:0 下载免费PDF全文
Growth of inhibition patterns provide evidence for a common nucleoside transport or utilization system, a separate system or systems for adenine transport, and another adaptable mechanism of adenosine transport. 相似文献
312.
Clint A. Penick Beth Trobaugh Colin S. Brent Jürgen Liebig 《Journal of Insect Behavior》2013,26(1):23-34
In lower termites, functionally sterile larval helpers are totipotent—capable of becoming reproductively active with the loss of their colony’s king or queen. Full reproductive development may take several weeks, but initiation of this developmental response most likely occurs shortly after colony members detect when a reproductive-specific signal is missing. We investigated the early response of termite helpers to the removal of their king and queen in the basal termite species Zootermopsis nevadensis. Within 6–12 h after reproductives were removed, helpers displayed an increase in head-butting—a behavior associated with dominance in other termite species as well as in closely related roaches. The loss of just one reproductive, either the king or queen, was also sufficient to cause an increase in head-butting. We did not find evidence, however, that this response was sex-specific: males and females were equally likely to increase head-butting independent of the sex of the reproductive that was removed. Finally, we discovered that reproductive-specific compounds present on the cuticle of king and queen termites were also present in their feces, but the presence of the feces did not seem sufficient to inhibit the increased head-butting after the reproductives were removed. Collectively, these results indicate that termite workers readily detect the loss of reproductives in their colony and that they at least initially respond in a non sex-specific manner. 相似文献
313.
Mark Merchant Clint Kinney Paige Sanders 《Comparative biochemistry and physiology. Part D, Genomics & proteomics》2009,4(4):300-304
Blood was collected from three juvenile alligators (Alligator mississippiensis) before, and again 24 h after, injection with bacterial lipopolysaccharide (LPS). The leukocytes were collected from both samples, and the proteins were extracted. Each group of proteins was labeled with a different fluorescent dye and the differences in protein expression were analyzed by two dimensional differential in-gel expressions (2D-DIGE). The proteins which appeared to be increased or decreased by treatment with LPS were selected and analyzed by MALDI-TOF to determine mass and LC–MS/MS to acquire the partial protein sequences. The peptide sequences were compared to the NCBI protein sequence database to determine homology with other sequences from other species. Several proteins of interest appeared to be increased upon LPS stimulation. Proteins with homology to human transgelin-2, fish glucose-6-phosphate dehydrogenase, amphibian α-enolase, alligator lactate dehydrogenase, fish ubiquitin-activating enzyme, and fungal β-tubulin were also increased after LPS injection. Proteins with homology to fish vimentin 4, murine heterogeneous nuclear ribonucleoprotein A3, and avian calreticulin were found to be decreased in response to LPS. In addition, five proteins, four of which were up-regulated (827, 560, 512, and 650%) and one that exhibited repressed expression (307%), did not show homology to any protein in the database, and thus may represent newly discovered proteins. We are using this biochemical approach to isolate and characterize alligator proteins with potential relevant immune function. 相似文献
314.
315.
Jing-Ke Weng Takuya Akiyama Nicholas D. Bonawitz Xu Li John Ralph Clint Chapple 《The Plant cell》2010,22(4):1033-1045
Phenotypic convergence in unrelated lineages arises when different organisms adapt similarly under comparable selective pressures. In an apparent example of this process, syringyl lignin, a fundamental building block of plant cell walls, occurs in two major plant lineages, lycophytes and angiosperms, which diverged from one another more than 400 million years ago. Here, we show that this convergence resulted from independent recruitment of lignin biosynthetic cytochrome P450-dependent monooxygenases that route cell wall monomers through related but distinct pathways in the two lineages. In contrast with angiosperms, in which syringyl lignin biosynthesis requires two phenylpropanoid meta-hydroxylases C3′H and F5H, the lycophyte Selaginella employs one phenylpropanoid dual meta-hydroxylase to bypass several steps of the canonical lignin biosynthetic pathway. Transgenic expression of the Selaginella hydroxylase in Arabidopsis thaliana dramatically reroutes its endogenous lignin biosynthetic pathway, yielding a novel lignin composition not previously identified in nature. Our findings demonstrate a unique case of convergent evolution via distinct biochemical strategies and suggest a new way to genetically reconstruct lignin biosynthesis in higher plants. 相似文献
316.
Littoral macroinvertebrates are increasingly used for assessing the ecological status of lakes according to the EU Water Framework
Directive. This requires harmonised sampling methods, but information on the appropriate spatial scale of the sampling as
well as on the adequate sample sizes are mostly lacking. In this study, we compared the spatial variability of littoral (<1.2 m
water depth) macroinvertebrate community composition within habitats and within sites to test whether habitat-specific sampling
can reduce their spatial variability. Furthermore, we determined the sample size necessary to obtain maximum species richness
for a given habitat type. Spatial variability of macroinvertebrate community composition was significantly lower within habitats
than within sampling sites, except for communities of coarse woody debris. Species–area curves revealed that a sample size
of 1 m2 per habitat was not sufficient to obtain the maximum species richness due to the dominance of rare species, which suggests
that compilation of taxon inventories may require more exhaustive sampling with sampling sizes substantially larger than 1 m2. Separate analysis for species assigned to incidence classes showed that a mean area of 0.63 m2 per habitat is sufficient to record all species with frequent and medium incidences, and 76% of the rare species. We conclude
that habitat-specific sampling is an effective way to reduce the inherent spatial variability of littoral macroinvertebrate
communities and that a sample size of 0.63 m2 per habitat is sufficient to represent their dominant and subdominant elements. The application of this adequate sample size
to other lake types than large oligotrophic lakes has to be exercised with caution, in particular if community composition
and richness patterns differ. However, our results are based on data from lakes that represent the typical lake type found
throughout the Central Baltic ecoregion ensuring its wider applicability in this ecoregion. 相似文献
317.
Use of the polymerase chain reaction in detection of culturable and nonculturable Vibrio vulnificus cells. 总被引:5,自引:0,他引:5
Vibrio vulnificus is a human pathogen associated with consumption of raw oysters. During the colder months the organism apparently enters a viable but nonculturable state and thus cannot be cultured by ordinary bacteriological methods. For this reason, another means of detecting this bacterium is necessary. In the present study we utilized the polymerase chain reaction (PCR) to detect V. vulnificus DNA, thus eliminating the problem of nonculturability. DNA from both culturable and nonculturable cells of V. vulnificus was amplified by PCR with primers flanking a 340-bp fragment of the cytotoxin-hemolysin gene. As little as 72 pg of DNA from culturable cells and 31 ng of DNA from nonculturable cells could be detected. Fifty cycles of a two-step reaction (30 s [each] at 94 and 65 degrees C) were found to be optimal as well as more time efficient than the three-step PCR. The total procedure from the point of DNA extraction to observation on a gel required less than 8 h. Possible reasons for the difficulties encountered in amplifying DNA from nonculturable cells, e.g., gene rearrangement or loss of the hemolysin gene, are discussed. 相似文献