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   12548篇
  免费   394篇
各国政治   537篇
工人农民   476篇
世界政治   907篇
外交国际关系   399篇
法律   7631篇
中国政治   78篇
政治理论   2807篇
综合类   107篇
  2020年   143篇
  2019年   209篇
  2018年   256篇
  2017年   302篇
  2016年   281篇
  2015年   210篇
  2014年   261篇
  2013年   1252篇
  2012年   287篇
  2011年   349篇
  2010年   265篇
  2009年   340篇
  2008年   326篇
  2007年   346篇
  2006年   336篇
  2005年   320篇
  2004年   306篇
  2003年   323篇
  2002年   308篇
  2001年   458篇
  2000年   406篇
  1999年   328篇
  1998年   195篇
  1997年   156篇
  1996年   164篇
  1995年   165篇
  1994年   163篇
  1993年   153篇
  1992年   252篇
  1991年   266篇
  1990年   261篇
  1989年   261篇
  1988年   246篇
  1987年   238篇
  1986年   270篇
  1985年   272篇
  1984年   245篇
  1983年   225篇
  1982年   158篇
  1981年   134篇
  1980年   121篇
  1979年   155篇
  1978年   90篇
  1977年   114篇
  1976年   101篇
  1975年   74篇
  1974年   92篇
  1973年   87篇
  1972年   80篇
  1971年   69篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
981.
This article analyzes the impact of policy variables--employer accommodations, state Social Security Disability Insurance (DI) allowance rates, and DI benefits--on the timing of an application for DI benefits by workers with a work-limiting health condition starting when their health condition first begins to bother them. The analysis uses a rich mixture of personal and employer characteristics from the Health and Retirement Study linked to Social Security administrative records. We find that most workers do not apply immediately for DI benefits when they are first bothered by a health condition. On the contrary, the median working-age man with a work-limiting condition waits 7 years after that time before applying, and the median working-age woman waits 8 years. Although the risk of applying for benefits is greatest in the year following onset, only 16 percent of men and 13 percent of women in our sample apply within the first year, and the risk of application falls thereafter. That finding suggests that institutional factors, in addition to health factors, may play a role in the timing of DI applications. Using kernel density estimates of the distribution of application and nonapplication ordered by state allowance rates (the rate of acceptance per DI determination in each state), we find that both men and women who live in states with high allowance rates are disproportionately more likely to apply for benefits in the first year after their condition begins to bother them than are those in states with low allowance rates. Using life-table analysis, we also find that men and women who are accommodated by their employers are significantly less likely to apply for DI benefits in each of the first few years after their condition begins to bother them than are those who are not accommodated. On the basis of this evidence, we include these policy variables in a model of the timing of DI application that controls for other socioeconomic variables as well as health. Using a hazard model, we find that workers who live in states with higher allowance rates apply for DI benefits significantly sooner than those living in states with lower allowance rates following the onset of a work-limiting health condition. Workers who are accommodated following the onset of a work-limiting health condition, however, are significantly slower to apply for DI benefits. Using the mean values of all explanatory variables, we estimate the relative importance of changes in these policy variables on the speed with which workers apply for benefits after onset. We find that the mean time until application for men is 10.22 years. Universal accommodations following onset would delay application by 4.36 years. In contrast, a 20 percent decrease in state allowance rates would delay application by only 0.88 years. For working-age women, the average expected time until application once a condition begins to bother them is 10.58 years. Universal accommodations would delay that by 3.76 years, and a 20 percent decrease in allowance rates would delay it by 1.47 years. A complication in this analysis is that the policy variables are to some degree endogenous. Accommodation is probably offered more often to workers who want to continue working. Allowance rates are chosen by states on the basis of federal policy and local choices and probably in part on the health condition of workers in the state. Therefore, our estimates are upper bounds of these policy effects. Still, we believe we provide evidence that the social environment faced by workers with work-limiting health conditions can significantly influence their decision to apply for DI benefits, holding their specific health conditions constant.  相似文献   
982.
983.
Artifactual injuries of the larynx produced by resuscitative intubation   总被引:3,自引:0,他引:3  
Over a period of 9 months we examined a series of 50 deaths due to natural and unnatural causes in which there had been endotracheal intubation and chest compression during resuscitation at the scene or in the emergency department shortly before death. In 37 of 50 cases (74%) there were airway injuries directly resulting from the intubation procedure which we documented using a standardized protocol and photography. Specific airway injuries, ranging from petechiae to contusions, included oral injury (28%), posterior pharyngeal injury (16%), epiglottic injury (22%), piriform recess injury (12%), laryngeal and tracheal mucosa injury (64%), strap muscle hemorrhage (14%), and cutaneous injury of the neck (4%). In addition, we recorded the presence of facial (6%) and conjunctival petechiae (21%) and attributed these changes to resuscitative chest compression. No cases had associated fractures of the hyoid or thyroid cartilage. Based on our findings, we conclude that resuscitative intubation can cause artifactual injury that may mimic inflicted injuries caused by neck compression, including strangulation and neck holds.  相似文献   
984.
Hemorrhagic disease of the newborn (HDN) is usually a self-limiting hemorrhagic disorder of childhood that occurs as a result of vitamin K deficiency. It may be defined as early or late form depending on the time of onset related to birth. HDN is recognized as one of several bleeding disorders that can mimic the findings of nonaccidental head injury and may lead to a mistaken diagnosis of child abuse. We present a single fatal case of late-onset HDN with illustration of hematologic assays that can be performed to assist the pathologist in making the correct diagnosis of HDN.  相似文献   
985.
986.
987.
988.
989.
990.
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