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101.
C J O'Donnell K B Meyer J V Jones T Benton E S Kaneshiro J S Nichols F W Schaefer 《Applied and environmental microbiology》1984,48(3):618-625
Destruction rates of parasite eggs in stored sludge were examined to help understand the fate of these agents of enteric diseases in sludge lagoons. Eggs from the roundworms, Ascaris spp., Toxocara spp., Trichuris spp., and the tapeworm, Hymenolepis spp., were treated with domestic sludges by aerobic or anaerobic processes. Sludge samples seeded with eggs were stored at 4 or 25 degrees C or in a container inserted into the ground to simulate lagoon conditions. The number of eggs recovered from the samples decreased with storage time. The viability and infectivity of eggs recovered were related to the storage temperature; i.e., the eggs stored at 4 degrees C remained viable longer than those stored at 25 degrees C. After 25 months at 4 degrees C, the Toxocara eggs and some Ascaris eggs remained both viable and infective, whereas most of these eggs stored at 25 degrees C were rendered nonviable after 10 to 16 months of storage in sludge. Although storage temperature was found to be the most important factor affecting the destruction and viability of these eggs, other factors, such as the type of sludge digestion, whether or not the eggs were digested along with the sludge or added later, storage in the soil versus sludge, pH, and egg species also exhibited some minor effects. These controlled laboratory studies suggest that lagooning of sludge can be an effective method for the elimination of parasite eggs, particularly in warmer geographical locations. 相似文献
102.
It is speculated that life originated in a small, shallow body of water containing concentrated prebiotic organic feedstocks, inorganic compounds, and catalytic agents in a diversity of microenvironments. This pond was formed by an improbable, fortuitous soft-landing of a cometary nucleus, or fragment thereof, on the surface of a suitable planet with an atmosphere in an appropriate thermodynamic state, such as Earth. 相似文献
103.
The role of the chorion in the mechanism of respiration is examined for the egg of Megaselia imitatrix. An air layer in the chorion is not essential for respiration, and oxygen can be absorbed through a hydrophilic pathway in the chorion by diffusion from the surrounding water. A model based on the diffusion of oxygen through the surface layer of the water down to the depth of the egg is proposed and presented in detail. 相似文献
104.
The architects of punctuated equilibrium and species selection as well as more recent workers (Vrba) have narrowed the original formulation of species selection and made it dependent upon so-called emergent characters. One criticism of this narrow version is the dearth of emergent characters with a consequent diminution in the robustness of species selection as an important evolutionary process. We argue that monomorphic species characters may at times be the focus of selection and that under these circumstances selection at the organism level is by-passed due to the absence of critical variance. Selection therefore shifts to the species level where variability reemerges in a clade. The absence of critical variance among organisms prevents effect macroevolution from operating. If species-wide properties are important in macroevolutionary processes, as we contend, systematists should pay more attention to their elucidation. 相似文献
105.
Benton M. Stidd 《American journal of botany》1978,65(2):243-245
Transverse sections through the distal region of a Dolerotheca specimen in a coal ball from the Calhoun coal of Illinois show the double rows of sporangia where they are free from one another. This leads to the conclusion that the sporangial rows should be regarded as extending inward from the campanulum cover rather than radiating outward from the center. This observation suggests that Dolerotheca is a synangium composed of many sporangial units of different lengths. 相似文献
106.
107.
Michael J. Benton 《Molecular phylogenetics and evolution》1998,9(3):398-407
Tests of a sample of 206 cladograms of mammals show that morphological data seem to predict phylogenies that match the known fossil record better than molecular trees. Three metrics that assess the rank order of branching points, the stratigraphic consistency of those nodes, and the ratio of ghost range to known range show a considerable diversity of values. Some published trees show excellent matching with fossil-record data; others show almost no correspondence whatsoever. Morphological trees are nearly twice as good as molecular trees in terms of matching of the rank orders of nodes and oldest fossils, while morphological trees are 10% better than molecular in terms of stratigraphic consistency of the nodes. The ratios of ghost range to known range are lower for molecular trees. Among the molecular trees, those based on gene data are considerably better than those based on protein sequences, at least in terms of the rank order of nodes and the stratigraphic consistency of nodes. Protein trees, however, were best of all in terms of minimizing the proportion of ghost range. These findings probably indicate real phenomena, but the match of molecular trees to the expectations of stratigraphy may improve as the study of molecular phylogeny matures. 相似文献
108.
Charles V. Benton Howard M. Hodge Donald L. Fine 《In vitro cellular & developmental biology. Plant》1978,14(2):192-199
Summary A cell culture method is described for the large-scale (50 to 150 1) production of Mason-Pfizer monkey virus and squirrel
monkey virus, two primate retroviruses. Virus production was achieved with suspension cultures of chronically infected A204
human rhabdomyosarcoma cells harvested and clarified in the logarithmic stages of cell culture growth. Methods for the subsequent
purification and concentration of virus material utilizing zonal centrifugation also are described. Applications of these
methodologies resulted in products that afforded biochemical comparisons of these agents in a manner such that host cell-derived
variations were minimized. These data indicated that high levels of production and efficient recovery and purification of
virus material were achieved.
This work was supported by Contract NO1-CO-25423 with the National Cancer Institute, National Institutes of Health. 相似文献
109.
D Roode R Liebschutz S Maulik T Friedemann D Benton D Kristofferson 《Nucleic acids research》1988,16(5):1857-1859
BIONET has made considerable progress in developing communication links among molecular biologists and biochemists worldwide. We describe these efforts and also note the many new enhancements to the BIONET system itself. 相似文献
110.
The quality of the fossil record and the accuracy of reconstructed phylogenies have been debated recently, and doubt has been cast on how far current knowledge actually reflects what happened in the past. A survey of 384 published cladograms of a variety of animals (echinoderms, fishes, tetrapods) shows that there is good agreement between phylogenetic (character) data and stratigraphic (age) data, based on a variety of comparative metrics. This congruence of conclusions from two essentially independent sources of data confirms that the majority of cladograms are broadly accurate and that the fossil record, incomplete as it is, gives a reasonably faithful documentation of the sequence of occurrence of organisms through time. 相似文献