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排序方式: 共有237条查询结果,搜索用时 15 毫秒
61.
Melissa Horne B.S. Kaylee R. Mastrianni Ph.D. Gray Amick Ph.D. Rachel Hardy B.S. Elissa Renneker B.S. Kevin W.P. Miller Ph.D. 《Journal of forensic sciences》2020,65(5):1709-1715
In the United States, federal law and many state laws differentiate between marijuana and industrial hemp through delta-9-tetrahydrocannabinol (THC) levels, whereby the latter is defined as ≤0.3 percent THC on a dry weight basis. Many traditional cannabis identification methods employed by crime laboratories cannot accurately determine total THC quantities in accordance with federal and state regulations, or do so with increased time, labor, and risks of instrument damage. In order to quickly distinguish positive marijuana samples, a method was developed to identify plant material with a total THC level >1%. This novel, automated dispersive pipette extraction (DPX) method uses tip-based technology and an automated liquid handler to enable fast, hands-free selective isolation of THC and its precursors for downstream gas chromatography–mass spectrometry (GC-MS) analysis. The workflow proceeds with no repetitive manual effort and reduced need for instrument maintenance while enabling crime labs to legally identify marijuana through the detection of total THC above 1%. Recovery of THC using the DPX extraction method was 93% at 30 µg/mL and 78% at 500 µg/mL. Similarly, THCA-A recovery was 100% at 30 µg/mL and 74% at 500 µg/mL. Samples evaluated in a blind study (proficiency, hemp, and nonprobative case samples) were all accurately identified as greater than or less than 1% THC, with samples containing <1% THC being identified as “cannabis” and subjected to more discriminative analysis as needed. 相似文献
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This article focuses on the degree of policy congruence, and by extension policy responsiveness, of U.S. federal‐ and state‐level GMO labeling laws from 2011–2016. Utilizing consumer survey data, evidence overwhelmingly demonstrates consumers prefer clear text‐based indication if food products contain genetically modified ingredients. However, the federal law adopted in 2016 mandates GMO labeling but with exceptions permitted to clear on‐package text labeling. The results of this study demonstrate that consumer preferences were not adequately represented at the federal level and were misaligned with state policy activities as captured in the aggregate outcome. State legislatures were actively proposing mandatory legislation with only a few cases of success, which did not adequately represent the wishes of the people. Given the misalignment and overall policy incongruence, the consequences of pending federal law are discussed in light of why the voices of the consumer choir were not heard by lawmakers. 相似文献
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Raposa Elizabeth B. Rhodes Jean Stams Geert Jan J. M. Card Noel Burton Samantha Schwartz Sarah Sykes Laura A. Yoviene Kanchewa Stella Kupersmidt Janis Hussain Saida 《Journal of youth and adolescence》2019,48(3):423-443
Journal of Youth and Adolescence - Mentoring programs, which pair youth with caring, non-parental adults with the goal of promoting positive youth development, are an increasingly popular strategy... 相似文献
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Marjorie Montague Wendy Cavendish Craig Enders Samantha Dietz 《Journal of youth and adolescence》2010,39(6):646-657
The purpose of this study was to investigate the trajectories of behavioral problems for a sample of predominately minority
adolescents (n = 212, 91% African-American and/or Hispanic, 45% boys, 55% girls) in a large, urban school district and to determine the
impact of parental and peer relationships, gender, and risk status on their development during middle and high school. Multi-level
growth modeling was the primary statistical procedure used to track internalizing and externalizing behavioral problems across
time. Results indicated that behavioral problems as rated by students’ teachers declined significantly for both boys and girls,
a finding that is in direct contrast to previous studies of adolescent behavior. The quality of parental relationships was
a strong predictor of both types of behavior whereas the quality of peer relationships predicted only internalizing behavioral
symptoms. These findings suggest that behavioral trajectories may be somewhat unique for this population underscoring the
need for additional research in this area. The findings also have implications for intervening with children and youth who
display behavioral problems during critical developmental periods. 相似文献
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Samantha C. Robbins B.Sc. Scott I. Fairgrieve Ph.D. Tracy S. Oost B.Sc. 《Journal of forensic sciences》2015,60(Z1):S182-S187
This study examined the effects of fire on the features associated with saw marks in bone. Both class and individual characteristics were examined using stereomicroscopy and scanning electron microscopy (SEM). Twenty-four semifleshed Sus scrofa L. tibiae were sawed into three sections with the middle section having deep and shallow false starts. Twelve saw blades of varying age and type were each used to cut two tibiae. In each case, the first tibia was burned in an outdoor open fire to the point of partial calcination. The second tibia, our control, was macerated using a heated enzyme solution. Controls and burned specimens were examined for the following characteristics: breakaway spur, tooth hop, false start, exit chipping, tooth imprint, breakaway notch, pull out striae, kerf flare, and blade drift. In general, there was parity in the observed characteristics in the burned samples using the SEM and the stereomicroscope. SEM observation, however, provided enhanced images, with the addition of observing individual tooth imprints, previously not visible. Therefore, this study recommends using an SEM for the examination of saw cuts in burnt bone. 相似文献
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