全文获取类型
收费全文 | 5250篇 |
免费 | 293篇 |
国内免费 | 1篇 |
专业分类
各国政治 | 377篇 |
工人农民 | 19篇 |
世界政治 | 594篇 |
外交国际关系 | 908篇 |
法律 | 1646篇 |
中国共产党 | 601篇 |
中国政治 | 777篇 |
政治理论 | 230篇 |
综合类 | 392篇 |
出版年
2023年 | 33篇 |
2022年 | 39篇 |
2021年 | 32篇 |
2020年 | 46篇 |
2019年 | 67篇 |
2018年 | 76篇 |
2016年 | 38篇 |
2015年 | 46篇 |
2014年 | 210篇 |
2013年 | 150篇 |
2012年 | 285篇 |
2011年 | 298篇 |
2010年 | 217篇 |
2009年 | 172篇 |
2008年 | 216篇 |
2007年 | 249篇 |
2006年 | 279篇 |
2005年 | 225篇 |
2004年 | 208篇 |
2003年 | 236篇 |
2002年 | 209篇 |
2001年 | 153篇 |
2000年 | 145篇 |
1999年 | 105篇 |
1998年 | 96篇 |
1997年 | 95篇 |
1996年 | 82篇 |
1995年 | 88篇 |
1994年 | 100篇 |
1993年 | 58篇 |
1992年 | 51篇 |
1991年 | 68篇 |
1990年 | 63篇 |
1989年 | 72篇 |
1988年 | 96篇 |
1987年 | 88篇 |
1986年 | 88篇 |
1985年 | 95篇 |
1984年 | 90篇 |
1983年 | 86篇 |
1982年 | 60篇 |
1981年 | 62篇 |
1980年 | 75篇 |
1979年 | 37篇 |
1977年 | 17篇 |
1964年 | 23篇 |
1962年 | 19篇 |
1961年 | 17篇 |
1960年 | 17篇 |
1959年 | 17篇 |
排序方式: 共有5544条查询结果,搜索用时 0 毫秒
251.
Fatty acid ethyl esters (FAEE) can be used as alcohol markers in hair. It was investigated in this study whether this diagnostic method is disturbed by hair care and hair cosmetics. Traces of ethyl myristate, ethyl palmitate, ethyl oleate and ethyl stearate were detected in all of 49 frequently applied hair care products by headspace solid phase microextraction (HS-SPME) and gas chromatography-mass spectrometry (GC-MS). The highest concentration was 0.003% in a hair wax. From experiments with separated hair samples of alcoholics as well as from the evaluation of the FAEE concentrations and the data about hair care of 75 volunteers (alcoholics, social drinkers and teetotalers) follows that usual shampooing, permanent wave, dyeing, bleaching or shading are of minor importance as compared to the drinking amount and other individual features. However, false positive results were found after daily treatment with a hair lotion containing 62.5% ethanol, with a deodorant and with a hair spray. As an explanation, it is assumed that FAEE are formed in the sebum glands also after regular topical application of products with a higher ethanol content. 相似文献
252.
This article describes a fully automated procedure for detecting cannabinoids in human hair samples. The procedure uses alkaline hydrolysis and headspace solid-phase dynamic extraction (HS-SPDE), followed by on-coating derivatization and gas chromatography-mass spectrometry (GC-MS). SPDE is a further development of solid-phase microextraction (SPME), based on an inside needle capillary absorption trap. It uses a hollow needle with an internal coating of polydimethylsiloxane as extraction and pre-concentration medium.Ten mg of hair were washed with deionised water, petroleum ether and dichloromethane. After adding deuterated internal standards, the sample was hydrolyzed with sodium hydroxide and directly submitted to HS-SPDE. After absorption of analytes for an on-coating derivatization procedure, the SPDE-needle was directly placed into the headspace of a second vial containing N-methyl-N-trimethylsilyl-trifluoroacetamide before GC-MS analysis. The limit of detection was 0.14 ng/mg for Delta(9)-tetrahydrocannabinol, 0.09 ng/mg for cannabidiol, and 0.12ng/mg for cannabinol. Absolute recoveries were in the range of 0.6 to 8.4%. Linearity was verified over a range from 0.2 to 20 ng/mg, with coefficients of correlation between 0.998 and 0.999. Intra- and inter-day precision were determined at two different concentrations and resulted in ranges between 2.3 and 6.0% (intra-day) and 3.3 and 7.6% (inter-day). Compared with conventional methods of hair analysis, this automated HS-SPDE-GC-MS procedure is substantially faster. It is easy to perform without using solvents and with minimal sample quantities, and it yields the same sensitivity and reproducibility. Compared to SPME, we found a higher extraction rate, coupled with a faster automated operation and greater stability of the device. 相似文献
253.
"第三条道路"研究既有政策的一面,也有政治的一面.前者涉及社会民主党20世纪80年代以来所推行的政策,后者涉及政党竞争问题.本文主要研究"第三条道路"政治的一面,目的是通过对丹麦和荷兰社会民主党发展历程的回顾和分析,回答社会民主党为什么走上"第三条道路"和各国的变革顺序为什么不同的问题. 相似文献
254.
Already the Celts and ancient Germanic peoples knew about the poisonousness of the yew, which played an important part in the mythology of these civilizations. For hunting, the arrows were made poisonous with yew juice, and yew leaves were used for homicide and suicide. In modern times taxine is rarely used with suicidal intent, although this method is actually recommended on the respective Websites. After a 14-year-old boy had intensively studied poisonous plants and methods of suicide on various Websites, he cut leaves from a yew tree (taxus baccata) in his parents' garden, crushed and ingested them and died soon afterwards. At the forensic autopsy pieces of the partially crushed, partially completely preserved yew leaves were found in the stomach. The histological findings were unspecific, e.g. marked general blood congestion of the internal organs and pronounced cerebral and pulmonary edema. When the tree leaves found in the stomach were viewed under the light microscope, a stoma typical of taxus was observed; chemical-toxicological investigations revealed 3,5-dimethoxyphenol in the gastric content, which is considered a marker for the ingestion of taxus. 相似文献
255.
The authors report on a woman who died on the age of 75 years and who was found dead in her dwelling with an extensive injury of the left thigh two days after the last sign of life. Together with the corpse a poodle was present in the dwelling. Due to the unusual localization totally beneath the clothes (trousers) and the morphology of the injury an unnatural cause of death was suspected. According to the autopsy findings and the histological results, postmortal animal scavenging caused by the poodle remained the only explanation for the injury. Supplementary DNA testing yielded final certainty. 相似文献
256.
The article describes problems related to immunochemical screening-tests with special regard to benzodiazepines, which are commonly used for therapeutic purposes. Focal points are adulteration, manipulation and handling of samples, the selection of cut-off-values, specificity and cross-reactivity, influence of biotransformation and frequently observed pitfalls in the interpretation of the analytical results. 相似文献
257.
258.
259.
Förster R 《Archiv für Kriminologie》2001,208(1-2):24-31
A five-year-old boy was fatally injured by a stab and a cut to the throat. The suspected offender, an acquaintance of the victim's mother, stated that he had been disturbed by the boy while attempting suicide and had therefore killed the boy. The suspect showed superficial cuts on both wrists and three shallow stabs on the right-hand side of the abdomen. The purpose of the forensic investigations was to answer the question if the suspect's statement could be confirmed or if the attempted suicide took place after killing the boy. The blood-smeared blade of the knife was divided into different sectors with the cutting edge and the tip of the blade being examined separately from the sides. The blood traces from the different blade sectors were then typed in 12 different DNA regions by PCR (polymerase-chain-reaction). It could be demonstrated that the strong blood traces on the sides of the blade originated from the victim alone, whereas in the area of the edge and the tip of the blade the amount of the victim's blood was negligible compared with that of the suspected offender. The explanation for this finding is that in the areas of the edge and the tip of the knife the blood of the victim must have been replaced by the blood of the suspected perpetrator, which means that the suicidal injuries were the last to be caused by the knife. 相似文献
260.
The Hamburg Institute of Forensic Medicine analysed 388 deaths of homeless people between 1990 and 1998 considering demographic data, post-mortem results and autopsy findings. The manner of death was either unnatural or unascertained; the autopsy rate amounted to 43.8%. The results confirm the observation discussed in the last few years that homeless people are usually in a poor state of health. In relation to the average age of death, which is 44.5 years, the number of previous diseases is high. Unnatural causes (excluding homicides) account for a high percentage, viz. 62.6%, primarily intoxications. The most frequent natural cause of death is infection (16.8%). Women account for 8.5% of the deaths with their organ findings and causes of deaths being different from those of homeless men in terms of distribution and incidence. The data presented in this report may be helpful for the improvement of the present system of medical help in Hamburg. 相似文献