首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   12539篇
  免费   213篇
各国政治   448篇
工人农民   1171篇
世界政治   637篇
外交国际关系   518篇
法律   6536篇
中国共产党   1篇
中国政治   21篇
政治理论   3372篇
综合类   48篇
  2021年   24篇
  2020年   57篇
  2019年   66篇
  2018年   1358篇
  2017年   1306篇
  2016年   1153篇
  2015年   151篇
  2014年   100篇
  2013年   709篇
  2012年   305篇
  2011年   1005篇
  2010年   1105篇
  2009年   699篇
  2008年   845篇
  2007年   809篇
  2006年   145篇
  2005年   195篇
  2004年   292篇
  2003年   258篇
  2002年   160篇
  2001年   80篇
  2000年   96篇
  1999年   80篇
  1998年   109篇
  1997年   87篇
  1996年   66篇
  1995年   105篇
  1994年   91篇
  1993年   71篇
  1992年   74篇
  1991年   57篇
  1990年   56篇
  1989年   66篇
  1988年   69篇
  1987年   75篇
  1986年   64篇
  1985年   78篇
  1984年   78篇
  1983年   59篇
  1982年   61篇
  1981年   55篇
  1980年   43篇
  1979年   50篇
  1978年   46篇
  1977年   45篇
  1976年   28篇
  1975年   23篇
  1974年   25篇
  1973年   24篇
  1969年   21篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
891.
The neurologic manifestations of thallium poisoning include a severely painful ascending peripheral neuropathy, autonomic dysfunction, cranial nerve abnormalities, and a toxic encephalopathy. Although thallium has a short half-life, these neurologic manifestations commonly progress, even as the blood concentration of thallium decreases. This suggests either that thallium persists in neuronal tissues or that it initiates an injury cascade that takes time to fully manifest. As the latter mechanism is consistent with many toxin exposures, the concept of a central nervous system reservoir for thallium is often discounted. A recent case provided a unique opportunity to evaluate this possibility. A 48-year-old man was acutely and chronically thallium poisoned by his common-law wife. During his initial exposures, only gastrointestinal symptoms manifested. Following an acute ingestion, hospitalization was required. Over 3 days, his symptoms rapidly progressed from a severely painful neuropathy to slurred speech, ptosis, confusion, coma, respiratory insufficiency, and death. Because of considerations of alternative diagnoses, 2 lumbar punctures were performed, one on admission and another on the day of his death. Serum thallium concentrations obtained from stored blood samples were paired with spinal fluid concentrations from the same days. On day 1, serum and spinal fluid concentrations were 8700 mu/L and 1200 mu/L, respectively. On day 3, although the serum concentration had fallen to 7200 mu/L, the spinal fluid concentration had increased to 2100 mu/L. This case provides evidence to support the hypothesis that thallium distributes into the central nervous system more slowly than the blood compartment, and this may in part account for the progression of neurologic findings in the setting of decreasing serum concentrations.  相似文献   
892.
The authors present a case of sudden death in a previously healthy 36-year-old male. At autopsy there were bilateral pulmonary thromboemboli and right ventricular dilatation. Histologic findings in the lungs included recanalized, old thrombi and evidence of pulmonary hypertension. Genetic analysis for hereditary risk factors was heterozygous positive for the prothrombin G20210A mutation. Implications of this finding, its history and the diagnostic technique shall be discussed. The authors recommend that all cases of deep venous thromboses and pulmonary thromboemboli lacking known risk factors be evaluated for newly described genetic variations associated with an increased risk for venous thrombosis.  相似文献   
893.
A series of recent papers have shown how to formulate complex problems of forensic DNA identification inference, such as occur in disputed paternity or criminal identification cases, in terms of Probabilistic Expert Systems (PESs). However, at the present time, general purpose PES software is not particularly well suited to the repetitive tasks of: specifying an appropriate set of marker networks for a specific problem; for editing the many local conditional probability tables; and combining evidence from several genetic markers to evaluate likelihoods. Here, I describe a user-friendly prototype software tool called FINEX developed both to automate such tasks and also to evaluate likelihoods of interest. Ease of use is achieved by a graphical specification language that enables a user to quickly specify a range of forensic DNA problems. I describe the algorithms by which FINEX converts the user input in the graphical specification language and data on observed markers to the Bayesian networks used in PES.  相似文献   
894.
This article profiles self-reported substance use, health, and mental health problems among a sample of incarcerated women in Kentucky as well as lifetime service utilization. Findings indicate that a high percentage of women reported use of alcohol, cocaine, and multiple substances during the month before incarceration. In addition, participants reported common health problems such as dental, female reproductive, physical injuries, and mental health problems including depression and anxiety. Participants reported moderate use of emergency room and mental health treatment but limited substance abuse treatment utilization. Implications for criminal justice programs and linkages with community-based aftercare services for women are recommended based on findings that health and mental health problems are associated with service utilization before incarceration.  相似文献   
895.
  This paper places the contemporary study of regionalism in historical context. It argues that the study of regionalism has occurred in two waves. The first gathered pace as a sub-field of International Relations from the late 1950s and the second emerged in the context of the globalisation of the late 1980s and the 1990s. RID="*" ID="*" This paper, originally presented as a lecture to the Asia Europe Foundation University, 7th Summer School, Barcelona: November 11, 2002, represents an abbreviated and revised version of Shaun Breslin and Richard Higgott (2000) Studying Regions: Learning from the Old Constructing the New, New Political Economy 5 (3): 333–352. Permission of the Editors of New Political Economy to publish in this form is gratefully acknowledged. The support of the Economic and Social Research Council in the writing of this paper is also gratefully acknowledged.  相似文献   
896.
It has been suggested that inter-canine width plus 57% of the cumulative distance between the lateral aspect of the canines and the pupil centers can be used to estimate mouth width. Evidence also suggests that the distance between the medial irises approximates actual mouth width fairly well. However, these soft tissue prediction guidelines are limited because they rely on accurate medio-lateral positioning of the pupils within the orbits, for which no systematic empirical evidence appears to exist at this stage. It would, therefore, be more appropriate to use only known hard tissue landmarks in mouth width prediction. This study reports the results of using inter-canine width as a percentage of mouth width for its prediction. This method seems favorable in comparison to the other guidelines because it is as accurate, uses known hard tissue landmarks, and does not rely on assumptions concerning pupil location. Estimating mouth width by using the canines alone, therefore, seems the best guideline to use in facial approximation techniques, at least given knowledge existing at this stage.  相似文献   
897.
Thermal transfer printing refers to printing processes that utilize heat to produce an image by either physical or chemical means or by a combination of both. As the technology has improved and the supplies have become less expensive, the use of thermal printing in the personal and business markets has increased significantly. Specifically, dye diffusion thermal transfer and thermal mass transfer have become predominant in the production of counterfeit credit cards, drivers' licenses, and other types of documents produced on plastic media. Chemical analysis by means of thin layer chromatography (TLC) has proven to be useful in characterizing various types of inks (e.g., writing and inkjet inks). In this study, the authors examined 81 different samples that included a total of 54 printer samples (43 photographic prints on paper and eleven plastic card samples) and 27 printer ribbons. A new TLC method was developed and tested utilizing a solvent system (80% n-hexane, 3% methyl ethyl ketone, and 17% ethyl acetate) that is capable of producing excellent resolution.  相似文献   
898.
A 29-year old female with a history of depression was found dead in a hotel room. The death scene investigation found empty pill bottles and an empty liter bottle of wine. Metaxalone, a centrally acting muscle relaxant, along with citalopram, ethanol, and chlorpheniramine were identified in the postmortem samples and quantitated by gas chromatography-mass spectrometry. The concentration of metaxalone in femoral vein blood was 39 mg/L. The heart blood concentration was 54 mg/L. Femoral vein blood concentrations of citalopram and chlorpheniramine were 0.77 mg/L and 0.04 mg/L, respectively. Ethanol levels were 0.13 g/dL in vitreous and 0.08 g/dL in heart blood. Other tissue samples were also analyzed. The authors consider the metaxalone concentrations toxic and potentially fatal. The citalopram concentrations were lower than those reported in fatal cases for this drug alone. Death was ascribed to polydrug abuse/overdose with metaxalone a major contributor. This represents the first reported case to our knowledge in which a metaxalone overdose significantly contributed to death.  相似文献   
899.
Subject Acquisition for Web-Based Surveys   总被引:1,自引:0,他引:1  
  相似文献   
900.
Disability has high societal and personal costs. Various disparate federal and state programs attempt to address the economic and social needs of people with disabilities. Presumably workplace injuries and accidents are an important source of disability. Yet separate public policies and research literatures have evolved for these two social problems--disability and workplace injuries--despite their relatedness. This article seeks to document the overlap between these two phenomena in estimating the proportion of the disabled population whose disability was caused by workplace injury, accident, or illness using the Health and Retirement Study of 1992. The results point toward the need for initiatives to reduce disability that focus on work-related causes, which are a common pathway to disability, and that may result in substantial savings in federal programs.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号