全文获取类型
收费全文 | 3430篇 |
免费 | 55篇 |
专业分类
各国政治 | 97篇 |
工人农民 | 93篇 |
世界政治 | 145篇 |
外交国际关系 | 95篇 |
法律 | 2650篇 |
中国政治 | 17篇 |
政治理论 | 351篇 |
综合类 | 37篇 |
出版年
2020年 | 33篇 |
2019年 | 34篇 |
2018年 | 54篇 |
2017年 | 42篇 |
2016年 | 63篇 |
2015年 | 28篇 |
2014年 | 51篇 |
2013年 | 245篇 |
2012年 | 86篇 |
2011年 | 132篇 |
2010年 | 79篇 |
2009年 | 61篇 |
2008年 | 108篇 |
2007年 | 121篇 |
2006年 | 106篇 |
2005年 | 84篇 |
2004年 | 121篇 |
2003年 | 113篇 |
2002年 | 108篇 |
2001年 | 150篇 |
2000年 | 134篇 |
1999年 | 103篇 |
1998年 | 20篇 |
1995年 | 17篇 |
1993年 | 27篇 |
1992年 | 62篇 |
1991年 | 83篇 |
1990年 | 85篇 |
1989年 | 91篇 |
1988年 | 95篇 |
1987年 | 89篇 |
1986年 | 75篇 |
1985年 | 77篇 |
1984年 | 67篇 |
1983年 | 58篇 |
1982年 | 24篇 |
1981年 | 20篇 |
1979年 | 30篇 |
1978年 | 33篇 |
1977年 | 22篇 |
1976年 | 27篇 |
1975年 | 28篇 |
1974年 | 37篇 |
1973年 | 37篇 |
1972年 | 35篇 |
1971年 | 36篇 |
1970年 | 38篇 |
1969年 | 32篇 |
1968年 | 27篇 |
1967年 | 18篇 |
排序方式: 共有3485条查询结果,搜索用时 0 毫秒
941.
Preliminary research using on-line supercritical fluid extraction/gas chromatography-mass spectrometry (SFE/GC-MS) has shown that the natural and artificial surface components of human scalp hair are reproducible and differentiable. Therefore, these components may be useful for individualization or determining demographic characteristics or both. However, it is not known how the efficiency and selectivity of on-line SFE/GC-MS compares to other extraction methods. In this study, ultrasound, Soxhlet, and pressurized-fluid extraction were used to extract 1 mg to 1.3 g portions of a composite hair sample taken from an Asian male between the ages of 10 and 18. Percent extractables ranged from 0.9% to 5.6%, depending on the solvent used, and tended to increase with solvent polarity. Chemical analysis using GC/MS showed that the extracts contained large proportions of free fatty acids, squalene, cholesterol, and various wax esters. Finally, comparisons to SFE/GC-MS showed that this method possesses adequate efficiency, no observable differences in selectivity, and greater potential for miniaturization. 相似文献
942.
Ramdial PK Jogessar V Dada MA 《The American journal of forensic medicine and pathology》1999,20(4):369-373
Membranous fat necrosis (MFN) is a distinct abnormality in systemic and subcutaneous fatty tissue. Although ischemia and trauma have been implicated in its causation, the exact pathogenesis of MFN remains unknown. The deposition of metallic mercury in subcutaneous tissue due to accidental penetration or deliberate injection of mercury is unusual. Depending on the duration of the deposition, localized necrosis, suppuration, and granuloma formation have been described at mercury injection sites. We report subcutaneous MFN, a hitherto unrecognized histopathologic phenomenon at sites of mercury deposition, in a 21-year-old soccer player who had deliberate subcutaneous and intramuscular elemental mercury injections to improve his sporting performance. 相似文献
943.
Ethyl nitrite method is proposed as the tentative test for nitrites in studies of the blood and gastric contents. The sensitivity of the method in "pure" solutions is 17 micrograms/sample. The method is specific and its sensitivity is not inferior to routine chemical analyses of biological materials for nitrites. 相似文献
944.
Presents a modified method for restoring the shape and size of wounds on skin preparations. The advantages of the modification over the routine A. N. Ratnevski?'s method are enumerated. 相似文献
945.
Some aspects of simulation experiments in forensic medicine are discussed, specifically those in studies of biomechanics and expert evaluation of the probable circumstances of a head injury caused by falling on a plane from a standing posture. Based on mathematical simulation and multifactorial analysis of physical parameters characterizing the process of falling (inertia, angular velocity, etc.), the authors prove the possibility of differentiating between spontaneous falling of a victim and falling caused by an outer force, and estimating the value of this force. 相似文献
946.
The possibility of investigating pieces of material evidence of biological origin after exposure to various factors is evaluated. The possibility of detecting proteins of liquid media of human organism by electrophoresis in polyacrylamide denatured gel is investigated. The method is intended for identification of biological material in a state of grave destruction. Methodology of such studies is proposed. The data indicate that the structural integrity and qualitative composition of the spectrum of main serum proteins are retained after combined exposure to damaging factors and complete destruction of blood cells. 相似文献
947.
Kapustin AV 《Sudebno-meditsinskaia ekspertiza》1999,42(6):10-12
An early sign of cardiac ventricle fibrillation is described: numerous surface cracks in the myocardial fibers. The formation of cracks is the initial stage of myocardial fiber fragmentation. The cracks are detected by polarization microscopy in the absence of fragmentation or in myocardial sites without focal fragmentation. 相似文献
948.
Porodenko VA 《Sudebno-meditsinskaia ekspertiza》1999,42(6):18-20
The degree of development of subcutaneous fat and muscles of the back, filling of the gastrointestinal tract, increase in intra-abdominal pressure, and pathological processes, specifically, cysts, hydronephrosis, tumors, pelvic stones, etc., play a significant role in the development of renal injuries. A case with a kidney rupture resultant from a slight trauma in a 19-year-old soldier is presented. Analysis of nephrectomy, review and intravenous excretory urography, and pathological examination of the removed kidney showed third-stage hydronephrosis. This diagnosis was significant for evaluation of the severity of corporal injuries and for determining the punishment for the guilty subject. 相似文献
949.
950.