全文获取类型
收费全文 | 17392篇 |
免费 | 1446篇 |
专业分类
各国政治 | 822篇 |
工人农民 | 541篇 |
世界政治 | 1434篇 |
外交国际关系 | 718篇 |
法律 | 11321篇 |
中国共产党 | 1篇 |
中国政治 | 129篇 |
政治理论 | 3730篇 |
综合类 | 142篇 |
出版年
2023年 | 72篇 |
2021年 | 97篇 |
2020年 | 430篇 |
2019年 | 475篇 |
2018年 | 540篇 |
2017年 | 627篇 |
2016年 | 648篇 |
2015年 | 531篇 |
2014年 | 567篇 |
2013年 | 2146篇 |
2012年 | 428篇 |
2011年 | 521篇 |
2010年 | 679篇 |
2009年 | 643篇 |
2008年 | 423篇 |
2007年 | 456篇 |
2006年 | 536篇 |
2005年 | 457篇 |
2004年 | 445篇 |
2003年 | 427篇 |
2002年 | 423篇 |
2001年 | 557篇 |
2000年 | 456篇 |
1999年 | 391篇 |
1998年 | 229篇 |
1997年 | 218篇 |
1996年 | 186篇 |
1995年 | 214篇 |
1994年 | 233篇 |
1993年 | 189篇 |
1992年 | 298篇 |
1991年 | 323篇 |
1990年 | 278篇 |
1989年 | 291篇 |
1988年 | 272篇 |
1987年 | 238篇 |
1986年 | 271篇 |
1985年 | 287篇 |
1984年 | 271篇 |
1983年 | 246篇 |
1982年 | 193篇 |
1981年 | 179篇 |
1980年 | 163篇 |
1979年 | 184篇 |
1978年 | 122篇 |
1977年 | 109篇 |
1976年 | 97篇 |
1975年 | 85篇 |
1974年 | 91篇 |
1973年 | 78篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
11.
Ana Celeste Ximenes Oliveira Ph.D. Alexandre Leão Ph.D. Karla Balzuweit Ph.D. Livia Siman Ph.D. Oscar Nassif Mesquita Ph.D. Luiz Orlando Ladeira Ph.D. Luiz Alberto Cury Ph.D. 《Journal of forensic sciences》2019,64(6):1867-1872
The optical and morphological properties of resveratrol were investigated. This nontoxic fluorescent natural material, emitting in the visible blue light, was used as an optical marker, enabling the enhancement of the image contrast coming from relief pictures marked on challenging surfaces. By applying appropriated imaging softwares, this marker was verified to be very useful in the latent fingerprint recognition deposited on different wood surface types, mainly those with high level of roughness, where conventional forensic materials do not allow effective fingerprint image visualization. 相似文献
12.
13.
In the early 1970s, Grand Canyon National Park intended to designate its land to “Wilderness,” including the controversial Colorado River corridor. However, by the end of the 1970s the potential for Wilderness designation was off the table, and would never seriously return for genuine consideration. Using Schattschneider's model of conflict, we explain how the organization of this conflict privileges the “causal story” of Wilderness opponents, and therefore why the canyon is not designated. It is our contention that members of Congress will not stand forward to support Wilderness designations without simultaneously providing benefits for extractive land use because (1) congressional representatives are more penalized for supporting than opposing Wilderness designations, (2) Wilderness advocacy groups do not pressure congressional delegates as firmly as opposition groups, and (3) key local congressional members are not likely to see Wilderness as a salient issue worth the risk of negative exposure. If these findings hold, the implication is that we may have reached the end of significant Wilderness designations in highly visible areas, unless critical aspects in land use conflict change. 相似文献
14.
In 1991 the FCC implemented a price cap plan for local exchange carriers' interstate access service designed to deal with the regulatory boundaries problem arising from the breakup of AT&T in 1984. The experience with the price cap plan demonstrates the difficulty of predicting productivity growth accurately and makes clear that regulators cannot depend upon a pure price cap plan to keep prices within a reasonable range of costs. With periodic reviews to readjust plan parameters, however, a price cap plan can maintain the rate-of-return close to the target rate-of-return without diminishing the price cap plan's incentives for efficient production. A simple method of recalculating the X-factor based on the rate-of-return over the previous three years worked well in simulations. If this procedure had been used over the price cap period 1991 to 2000, prices would have been 20 percent lower and expenditures on LECs' telecommunications service subject to a price cap would have been $3.8 billion lower. 相似文献
15.
While the concepts of race and ethnicity have been abused historically, they are potentially invaluable in epidemiology and public health. Epidemiology relies upon variables that help differentiate populations by health status, thereby refining public health and health care policy, and offering insights for medical science. Race and ethnicity are powerful tools for doing this. The prerequisite for their responsible use is a society committed to reducing inequalities and inequities in health status. When this condition is met, it is irresponsible not to utilize these concepts. 相似文献
16.
Ellen K. Marshall Ph.D. 《Journal of Police and Criminal Psychology》2006,21(1):62-71
The present study measured the existence of traumatic stress symptomatology as reported by certified law enforcement officers
within the State of Delaware. A questionnaire was devised which documented age, sex, race, education, years of service, marital
status, children, rank, position, and shift work. The questionnaire was divided into parts which assessed the exposure and
the frequency of specific traumatic incidents experienced in the line of duty, and the frequency of experienced traumatic
symptomatology criteria: re-experiencing, numbing, and arousal. 相似文献
17.
18.
Prosecution history estoppel generally bars patent infringementunder the doctrine of equivalents when a claim is narrowed byamendment during examination, but the tangential relationcriterion preserves that doctrine when the claim is narrowedin a manner unrelated to the particular equivalent which, itis alleged, infringes the patent. 相似文献
19.
20.