全文获取类型
收费全文 | 12145篇 |
免费 | 1290篇 |
专业分类
各国政治 | 442篇 |
工人农民 | 400篇 |
世界政治 | 932篇 |
外交国际关系 | 339篇 |
法律 | 9165篇 |
中国共产党 | 1篇 |
中国政治 | 89篇 |
政治理论 | 1991篇 |
综合类 | 76篇 |
出版年
2020年 | 356篇 |
2019年 | 364篇 |
2018年 | 430篇 |
2017年 | 496篇 |
2016年 | 487篇 |
2015年 | 453篇 |
2014年 | 441篇 |
2013年 | 1240篇 |
2012年 | 296篇 |
2011年 | 377篇 |
2010年 | 541篇 |
2009年 | 497篇 |
2008年 | 299篇 |
2007年 | 268篇 |
2006年 | 361篇 |
2005年 | 253篇 |
2004年 | 239篇 |
2003年 | 237篇 |
2002年 | 216篇 |
2001年 | 453篇 |
2000年 | 352篇 |
1999年 | 305篇 |
1998年 | 149篇 |
1997年 | 134篇 |
1996年 | 107篇 |
1995年 | 138篇 |
1994年 | 145篇 |
1993年 | 122篇 |
1992年 | 220篇 |
1991年 | 237篇 |
1990年 | 218篇 |
1989年 | 230篇 |
1988年 | 210篇 |
1987年 | 179篇 |
1986年 | 209篇 |
1985年 | 225篇 |
1984年 | 224篇 |
1983年 | 187篇 |
1982年 | 147篇 |
1981年 | 131篇 |
1980年 | 130篇 |
1979年 | 150篇 |
1978年 | 94篇 |
1977年 | 81篇 |
1976年 | 68篇 |
1975年 | 72篇 |
1974年 | 79篇 |
1973年 | 65篇 |
1972年 | 55篇 |
1971年 | 59篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
891.
In sexual assault cases, lubricant trace evidence may supplement biological evidence, or may be the primary physical evidence where biological evidence is unavailable. This study considered a total of 50 lubricants from condoms and personal lubricant products available in Australia. Differentiation of the samples was attempted using fluorescence examination, Fourier transform infrared spectroscopy (DRIFTS), gas chromatography-mass spectrometry, liquid chromatography-tandem mass spectrometry, and pyrolysis gas chromatography-mass spectrometry. Eleven of the samples were uniquely identified by the analysis scheme, while the remainder of the samples were separated into nine groups. As a result of this study, a recommended protocol for the detection and analysis of an "unknown" biological swab was produced. 相似文献
892.
目的探讨低氧、氧化应激中一氧化氮(NO)和氧自由基之间关系及其对培养神经元的损伤机理。方法对培养的新生大鼠神经细胞分别进行低氧、H2O2氧化应激处理和超氧化物歧化酶(SOD)抗氧化应激处理,用比色法等检测培养上清液中NO、丙二醛(MDA)、乳酸脱氢酶(LDH)和SOD含量变化指标。结果与对照组比较,低氧组和H2O2组的NO、LDH、MDA含量均显著增高,SOD含量显著降低,NO与SOD含量变化呈负相关关系。预先给予终浓度为200U/ml的SOD处理,可使神经细胞的NO、LDH和MDA释放量明显减少。各组间NO含量与LDH、MDA含量呈正相关关系。结论低氧、氧化应激促使神经元NO产生增多,NO有增加氧自由基对神经细胞的损伤作用。SOD具有清除氧自由基和减轻NO对神经元的损伤作用。 相似文献
893.
家兔死后眼玻璃体液锌、镍含量与 PMI关系的研究 总被引:6,自引:3,他引:3
目的寻找一种精确推定PMI的方法。方法应用电感耦合等离子体质谱(ICP-MS),检测了家兔死后96小时内眼玻璃体液锌、镍元素含量,探讨其与PMI的相关性。结果家兔死后24h内眼玻璃体液锌、镍元素含量与PMI显著相关,可作为推定早期PMI的参考指标,其二项式回归方程分别为y=0.1404x2-1.3351x+3.8298(R2=0.9202)、y=0.0043x2-0.0596x+0.2665(R2=0.9103)。结论家兔眼玻璃体液中Zn、Ni元素含量变化是推定早期PMI的参考指标之一。 相似文献
894.
895.
896.
897.
Raven KP Reay DT Harruff RC 《The American journal of forensic medicine and pathology》1999,20(1):31-36
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
898.
D Chute C Grove B Rajasekhara J E Smialek 《The American journal of forensic medicine and pathology》1999,20(2):131-135
This study reviews the causes of sudden death of 66 schizophrenic patients who presented to the Office of the Chief Medical Examiner (OCME) for the State of Maryland over a 3-year period from 1994 through 1996. We identified an increased incidence of suicide compared with the general population of OCME cases. This observation is consistent with reports by other investigators. The majority of the deaths were the result of natural diseases, mostly atherosclerotic cardiovascular disease. Accidents, suicides, and 1 homicide were also present in this group. 相似文献
899.
William U. Weiss Ph.D. Gerald Serafino Ph.D. Ann Serafino Walt Willson Jason Sarsany John Felton Ph.D. 《Journal of Police and Criminal Psychology》1999,14(1):38-42
The MMPI-2 and the Inwald Personality Inventory were employed to investigate the personality characteristics of dropouts from
a state police academy. A traditional model of training borrowed from military models was used at the academy rather than
a police generated model. Sensitive and independent individuals, more compatible with modern community policing methods may
have rejected police work as a result of the experience. 15 academy completers and 9 dropouts were used in the sample. Analyses
of the scales of the MMPI-2 and the Inwald Personality Inventory identified variables upon which the two groups differed.
The hypothesis that more sensitive, empathic and independent individuals were leaving the academy appeared to be supported. 相似文献
900.
Blake DC 《Whittier law review》1999,21(2):401-407