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941.
Ruth F. Itzhaki 《Molecular neurobiology》1994,9(1-3):1-13
Inherited cases of Alzheimer's disease (AD) comprise only a very small proportion of the total. The remainder are of unknown
etiopathogenesis, but they are very probably multifactorial in origin. This article describes studies on four possible factors:
aluminum; viruses—in particular, herpes simplex type I virus (HSV1); defective DNA repair; and head trauma. Specific problems
associated with aluminum, such as inadvertent contamination and its insolubility, have led to some controversy over its usage.
Nonetheless, the effects of aluminum on animals and neuronal cells in culture have been studied intensively. Changes in protein
structure and location in the cell are described, including the finding in this laboratory of a change in τ resembling that
in AD neurofibrillary tangles, and also the lack of appreciable binding of aluminum to DNA. As for HSV1, there has previously
been uncertainty about whether HSV1 DNA is present in human brain. Work in this laboratory using polymerase chain reaction
has shown that HSV1 DNA is present in many normal aged brains and AD brains, but is absent in brains from younger people.
Studies on DNA damage and repair in AD and normal cells are described, and finally, the possible involvement of head trauma
is discussed. 相似文献
942.
Abstract Modified oligodeoxynucleotides, 20 to 30 bases in length and containing “linker arm” bases, are chemically synthesized, then attached covalently to alkaline phosphatase in a 1:1 conjugate through a 19 atom spacer. Such conjugates hybridize rapidly and selectively to complementary sequences similar to unmodified oligomers, and allow colorimetrlc and fluorogenic detection of hybrids. 相似文献
943.
944.
Extreme genetic similarity does not predict non‐breeding distribution of two closely related warblers 下载免费PDF全文
Ruth E. Bennett Sara Barker Swarthout Jeffrey S. Bolsinger Amanda D. Rodewald Kenneth V. Rosenberg Ronald W. Rohrbaugh 《Journal of Field Ornithology》2017,88(2):156-168
Detailed knowledge of migratory connectivity can facilitate effective conservation of Neotropical migrants by helping biologists understand where and when populations may be most limited. We studied the migratory behavior and non‐breeding distribution of two closely related species of conservation concern, the Golden‐winged Warbler (Vermivora chrysoptera) and Blue‐winged Warbler (Vermivora cyanoptera). Although both species have undergone dynamic range shifts and population changes attributed to habitat loss and social interactions promoting competition and hybridization, full life‐cycle conservation planning has been limited by a lack of information about their non‐breeding ecology. Because recent work has demonstrated that the two species are nearly identical genetically, we predicted that individuals from a single breeding population would have similar migratory timing and overwintering locations. In 2015, we placed light‐level geolocators on 25 males of both species and hybrids in an area of breeding sympatry at the Fort Drum Military Installation in Jefferson and Lewis counties, New York. Despite extreme genetic similarity, non‐breeding locations and duration of migration differed among genotypes. Golden‐winged Warblers (N = 2) overwintered > 1900 km southeast of the nearest Blue‐winged Warbler (N = 3) and spent nearly twice as many days in migration; hybrids (N = 2) had intermediate wintering distributions and migratory timing. Spring migration departure dates were staggered based on distance from the breeding area, and all birds arrived at the breeding site within 8 days of each other. Our results show that Golden‐winged Warblers and Blue‐winged Warblers in our study area retain species‐specific non‐breeding locations despite extreme genetic similarity, and suggest that non‐breeding locations and migratory timing vary along a genetic gradient. If the migratory period is limiting for these species, our results also suggest that Golden‐winged Warblers in our study population may be more vulnerable to population decline than Blue‐winged Warblers because they spend almost twice as many days migrating. 相似文献
945.
Bret A. Collier Stephen S. Ditchkoff Charles R. Ruth Jr. Joshua B. Raglin 《The Journal of wildlife management》2013,77(1):165-171
Many monitoring programs for white-tailed deer (Odocoileus virginianus) on both private and public lands across the United States have long relied on the use of road-based spotlight surveys for monitoring population size and trends. Research has suggested spotlight surveys are ineffective and that road-based surveys for deer are biased because of highly variable detection rates. To evaluate variability in detection rates relative to the assumption that repeated surveys along roads will provide reliable trend data for use in calculating deer density estimates, we collected 5 years of thermal-imager and spotlight survey data using a multiple-observer, closed-capture approach. Using a Huggin's closed capture model, data bootstrapping, and variance components analyses, our results suggest that density estimates for white-tailed deer generated from data collected during road-based spotlight surveys are likely not reflective of the standing deer population. Detection probabilities during individual spotlight surveys ranged from 0.00 to 0.80 (median = 0.45) across all surveys, and differed by observer, survey, management unit, and survey transect replicate. Mean spotlight detection probability (0.41) and process standard deviation (0.12) estimates indicated considerable variability across surveys, observers, transects, and years, which precludes the generation of a correction factor or use of spotlight data to evaluate long-term trends at any scale. Although recommended by many state, federal, and non-governmental agencies, our results suggest that the benefit of spotlight survey data for monitoring deer populations is limited and likely represents a waste of resources with no appreciable management information gained. © 2012 The Wildlife Society. 相似文献
946.
947.
The effect of visible light on carotenoid content in the dermatophyte Trichophyton mentagrophytes ATCC 26323 was investigated. The fungus T. mentagrophytes accumulated several carotenoids when arthroconidiated on Sabouraud glucose agar at 37°C. When this fungus was irradiated with moderate fluence rates of white light, the resultant arthroconidia contained considerably less carotenoids in comparison with dark controls although growth and arthroconidiation of this fungus were not at all affected by visible light. The reduction of carotenoid content in arthroconidia was due primarily to blue light, although red light caused a slight decrease in pigmentation. The suppressive effect of visible light on pigmentation was fluence rate dependent. Carotenoid accumulation in arthroconidia was inversely and exponentially related to the fluence rate of light. Carotenoid formation in arthroconidiating T. mentagrophytes was neither photoinducible nor photostimulative. An analysis of isolated carotenoids revealed that visible light caused a quantitative reduction in pigmentation, and no single carotenoid was selectively decreased.Non-standard abbreviations PI
pigmentation index
-
r
coefficient of correlation 相似文献
948.
949.
950.
The activity of topoisomerase I in nuclear extracts increased about three-fold 5 min after gamma-irradiation (840-2500 rads) of human peripheral blood lymphocytes or cultured lymphoblastoid cells. The change may reflect modification of the enzyme by nuclear ADP-ribosyl transferase, which is known to be activated by DNA breaks. 相似文献