全文获取类型
收费全文 | 20527篇 |
免费 | 1371篇 |
专业分类
各国政治 | 787篇 |
工人农民 | 689篇 |
世界政治 | 1605篇 |
外交国际关系 | 567篇 |
法律 | 14318篇 |
中国共产党 | 2篇 |
中国政治 | 133篇 |
政治理论 | 3684篇 |
综合类 | 113篇 |
出版年
2021年 | 100篇 |
2020年 | 415篇 |
2019年 | 472篇 |
2018年 | 536篇 |
2017年 | 626篇 |
2016年 | 654篇 |
2015年 | 561篇 |
2014年 | 583篇 |
2013年 | 1991篇 |
2012年 | 466篇 |
2011年 | 615篇 |
2010年 | 706篇 |
2009年 | 670篇 |
2008年 | 532篇 |
2007年 | 480篇 |
2006年 | 582篇 |
2005年 | 464篇 |
2004年 | 460篇 |
2003年 | 436篇 |
2002年 | 422篇 |
2001年 | 838篇 |
2000年 | 708篇 |
1999年 | 542篇 |
1998年 | 310篇 |
1997年 | 267篇 |
1996年 | 216篇 |
1995年 | 242篇 |
1994年 | 275篇 |
1993年 | 239篇 |
1992年 | 375篇 |
1991年 | 419篇 |
1990年 | 393篇 |
1989年 | 415篇 |
1988年 | 394篇 |
1987年 | 345篇 |
1986年 | 412篇 |
1985年 | 396篇 |
1984年 | 358篇 |
1983年 | 333篇 |
1982年 | 244篇 |
1981年 | 235篇 |
1980年 | 206篇 |
1979年 | 260篇 |
1978年 | 163篇 |
1977年 | 149篇 |
1976年 | 133篇 |
1975年 | 103篇 |
1974年 | 141篇 |
1973年 | 127篇 |
1972年 | 118篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
72.
73.
74.
In the statistical interpretation of forensic glass evidence it is standard practice to make the assumption of homogeneity of the refractive index (RI) of the source glass, or of localized homogeneity. However, the work of Locke and Hayes showed that, for toughened windscreen glass, this assumption might not be true. This work is well cited, but there appears to have been little follow-on published research. Furthermore, the toughening process is something known to affect the refractive index, and is a process that float glass does not undergo. Float glass is a major component of casework in New Zealand and for that reason it would be interesting to know whether the findings of Locke and Hayes apply when dealing with float glass. In this paper we describe an experiment similar to that of Locke and Hayes, systematically examining the variation of RI in a pane of float window glass. It was found that, although there were no systematic differences in refractive index, there were observable differences across the pane. 相似文献
75.
Family courts and child welfare agencies across the country are charged with protecting the safety of our children. That mission has become more challenging with increasing federal legislation and decreasing funding. In Buffalo, N.Y., the Family Court and the Department of Social Services have teamed up to respond to this challenge. With minimal additional staffing and resources, they have led a collaboration of agencies and service providers to change the way business is done in child welfare. By engaging each other in an interagency system change effort, the amount of time children spend in foster care has been reduced. The collaboration has been able to accomplish in a relatively short time what no agency had previously been able to accomplish on its own. The beneficiaries have been the children and families of Erie County. 相似文献
76.
In the wake of the 1990 amendments to the Clean Air Act, localities across the United States initiated public information campaigns both to raise awareness of threats to air quality and to change behavior related to air pollution by recommending specific behavioral changes in the campaign messages. These campaigns are designed to reduce the health hazards associated with poor air quality and to avoid federal sanctions resulting from the failure to meet air quality standards. As in many other communities across the country, a coalition of government agencies and businesses initiated a public information campaign in the Atlanta metropolitan region to reduce certain targeted behaviors, mainly driving. A two‐stage model used to analyze data from a rolling sample survey shows that the centerpiece of the information campaign—air quality alerts—was effective in raising awareness and reducing driving in a segment of the population. When the overall information campaign was moderated by employers' participation in programs to improve air quality, drivers significantly reduced the number of miles they drove and the number of trips they took by car on days when air quality alerts were sounded. Public information campaigns can be successful in increasing awareness, but changing well‐established behaviors, such as driving, is likely to require institutional mediation to provide social contexts that support the behavioral change, as well. © 2003 by the Association for Public Policy Analysis and Management. 相似文献
77.
In many countries it is left to the discretion of the court to accept or reject conclusions based on sampling procedures as applied to the total drug exhibit. As an alternative to this subjective approach, a statistical basis is presented using binomial and hypergeometric distributions to determine a lower limit for the proportion of units in a population which contains a drug, at a given confidence level. A method for calculating the total weight of a drug present in a population within a given confidence interval is also presented. In the event of no failures (all units sampled contain a drug), a sample size of six or seven units is generally sufficient to state that a proportion of at least 0.70 of the population contains a drug at a confidence level of at least 90%. When failures do occur in the sample, point estimation is used as the basis for selecting the appropriate sample size. 相似文献
78.
We report a case of rapid death from thrombotic thrombocytopaenic purpura (TTP) in a young pregnant lady who developed full blown symptoms soon after caesarean section. Extensive intramyocardial confluent haemorrhages and widespread microthrombi in heart, brain, adrenals and kidney were found at autopsy. Thrombotic thrombocytopaenic purpura is an uncommon condition, which carries a high fatality rate if untreated. Awareness of this syndrome together with its high risk of sudden death underlines the importance of rapid diagnosis and treatment. 相似文献
79.
80.
C Moore S Browne I Tebbett A Negrusz W Meyer L Jain 《Forensic science international》1992,56(2):177-181
A new solid-phase extraction procedure for the determination of cocaine and benzoylecgonine in amniotic fluid, using high flow co-polymeric sorbents is reported. The recoveries of cocaine and benzoylecgonine within the range 0.1-1 mg/l were 95.7% and 50.3%, respectively. The use of high-flow sorbents allowed the easy extraction of amniotic fluid regardless of sample viscosity or physical nature. The use of these solid-phase columns provided many advantages over the more commonly used solvent extraction, including an increase in extraction speed and efficiency, reduced operator time, reduced solvent use and disposal volumes and exceptional extract quality. Further, the determination of amniotic fluid obtained from pregnant cocaine users may provide important information about handling of cocaine by the fetus at various gestational ages. The procedure was successfully applied to amniotic fluid from suspected cocaine abusers. 相似文献