全文获取类型
收费全文 | 12190篇 |
免费 | 629篇 |
专业分类
各国政治 | 570篇 |
工人农民 | 461篇 |
世界政治 | 1019篇 |
外交国际关系 | 431篇 |
法律 | 7960篇 |
中国共产党 | 1篇 |
中国政治 | 59篇 |
政治理论 | 2263篇 |
综合类 | 55篇 |
出版年
2023年 | 58篇 |
2021年 | 92篇 |
2020年 | 249篇 |
2019年 | 316篇 |
2018年 | 332篇 |
2017年 | 405篇 |
2016年 | 410篇 |
2015年 | 315篇 |
2014年 | 375篇 |
2013年 | 1291篇 |
2012年 | 322篇 |
2011年 | 375篇 |
2010年 | 333篇 |
2009年 | 335篇 |
2008年 | 350篇 |
2007年 | 333篇 |
2006年 | 330篇 |
2005年 | 287篇 |
2004年 | 300篇 |
2003年 | 271篇 |
2002年 | 262篇 |
2001年 | 487篇 |
2000年 | 447篇 |
1999年 | 306篇 |
1998年 | 196篇 |
1997年 | 155篇 |
1996年 | 128篇 |
1995年 | 129篇 |
1994年 | 151篇 |
1993年 | 141篇 |
1992年 | 201篇 |
1991年 | 223篇 |
1990年 | 207篇 |
1989年 | 215篇 |
1988年 | 206篇 |
1987年 | 196篇 |
1986年 | 232篇 |
1985年 | 210篇 |
1984年 | 165篇 |
1983年 | 170篇 |
1982年 | 114篇 |
1981年 | 120篇 |
1980年 | 85篇 |
1979年 | 132篇 |
1978年 | 74篇 |
1977年 | 75篇 |
1976年 | 70篇 |
1974年 | 77篇 |
1973年 | 67篇 |
1972年 | 70篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
291.
Noelia I. Zanetti DB Andrea Costantino DChem Natalia Lazzarini BSChem Adriana A. Ferrero DB Néstor D. Centeno DB 《Journal of forensic sciences》2021,66(1):245-254
Fluoxetine is a selective serotonin reuptake inhibitor, commonly used for the treatment of a variety of psychopathological conditions. As such, fluoxetine may be expected to appear in clinical and forensic cases. Dermestes maculatus De Geer (Coleoptera: Dermestidae) has been recognized as a relevant component of the insect fauna associated with decomposing human and animal remains. Experiments were conducted to study the effect of fluoxetine on developing D. maculatus using two‐drug administration models: a non‐living animal model (pork muscle) and a living one (Sus scrofa L. pigs). We assessed the duration of immature stages and total life cycle, as well as morphological parameters (body length, cephalic width, and weight). The effect of fluoxetine was studied at an overdose concentration: In the non‐living animal model the drug was mixed with macerated pork muscle (2000 mg/kg) and in the living animal model, pigs were given the drug orally (833 mg/kg). A control was used for each model. Daily observations were performed from the beginning to the end of the experiments. GC‐MS was used for drug detection and quantification. There were no statistically significant differences in the duration of immature stages, life cycle, larval mortality, morphological parameters, or sex ratio, between treatment and control, regardless of the drug administration model. Given that fluoxetine had no detectable effect on the development of D. maculatus, detection of this drug in forensic situations would not compromise the accuracy of PMI estimations. 相似文献
292.
Joseph Y.S. Cheng 《当代中国》2015,24(92):357-375
The economic rise of the BRICS (Brazil, Russia, India, China and South Africa) inevitably leads to a redistribution of power in the international system. Chinese leaders today accord a considerable priority to this group, and there are elements of realism, liberalism/institutionalism and constructivism in their approach. This article intends to study China's policy towards BRICS and examine the above elements so as to better understand how the Chinese leadership perceives China's role in the international system, and how it seeks to articulate its interests and enhance its influence. 相似文献
293.
294.
This article analyzes the reasons why individuals oppose the siting of nuclear waste repositories close to their hometowns. In a simple model based on survey data, we show that the willingness to accept such facilities largely depends on economic criteria, namely expected economic impacts and risk estimates. However, the predictive power of such a model is improved by focusing not only on the consequences—as economic models typically do—but also on the procedural aspects. We show that acceptable siting rules contribute positively to the willingness of local residents to host a noxious facility. Acceptable rules, it is found, are essentially fair rules. 相似文献
295.
Victoria S. Kwol Turgay Avci Kayode K. Eluwole Angela Dalhatu 《Journal of Public Affairs (14723891)》2020,20(3)
Food handlers are essential in the fight for the prevention of foodborne disease outbreaks as they are critical in ensuring the delivery of safe and healthy food to the consumers. The current study build on knowledge, attitude, and practice model (KAP) to investigate the impact of food handlers' knowledge and attitude on the hygienic‐sanitary conditions of food delivered to the consumers in Nigerian hospitality sector. Using data collected from food handlers in restaurants, hotels and hospitals in Jos metropolis of Nigeria, the study revealed that handlers applied food safety measures to the level of their knowledge. Further investigation revealed that KAP model works effectively in the case of food handlers in Jos. We conclude with recommendations for the industry and education institutes where handlers are trained. 相似文献
296.
Hayter Christopher S. Rasmussen Einar Rooksby Jacob H. 《The Journal of Technology Transfer》2020,45(1):1-8
The Journal of Technology Transfer - University technology transfer is often associated with formal transmission of science-based inventions, for instance through the licensing of patented... 相似文献
297.
Marloes E. M. Vester M.D. Ph.D. Kurt B. Nolte M.D. Ph.D. Gary M. Hatch M.D. Chandra Y. Gerrard M.P.H. B.S. Reinoud D. Stoel Ph.D. Rick R. van Rijn M.D. Ph.D. 《Journal of forensic sciences》2020,65(5):1568-1573
Postmortem computed tomography (PMCT) is integrated into the evaluation of decedents in several American medical examiner offices and medicolegal death investigative centers in many other countries. We retrospectively investigated the value of PMCT in a series of firearm homicide cases from a statewide centralized medical examiner’s office that occurred during 2016. Autopsies were performed or supervised by board-certified forensic pathologists who reviewed the PMCT scans prior to autopsy. PMCT scans were re-evaluated by a forensic radiologist blinded to the autopsy findings and scored by body region (head–neck, thoracoabdominal, and extremities). Injury discrepancies were scored using a modified Goldman classification and analyzed with McNemar’s test. We included 60 males and 20 females (median age 31 years, range 3–73). Based on PMCT, 56 (79.1%) cases had injuries relevant to the cause of death in a single body region (24 head–neck region, 32 thoracoabdominal region). Out of these 56 cases, 9 had a missed major diagnosis by PMCT outside that region, including 6 extremity injuries visible during standard external examination. Yet all had evident lethal firearm injury. We showed that PMCT identifies major firearm injuries in homicide victims and excludes injuries related to the cause of death in other regions when a single body region is injured. Although PMCT has a known limited sensitivity for soft tissue and vascular pathology, it can be combined with external examination to potentially reduce or focus dissections in some of these cases depending on the circumstances and medicolegal needs. 相似文献
298.
Adam Lanzarotta Ph.D. Michael D. Thatcher B.S. Lisa M. Lorenz B.S. JaCinta S. Batson M.S. 《Journal of forensic sciences》2020,65(5):1443-1449
A simple, quick, selective, sensitive, and effective field-friendly method capable of being used by nonexperts has been developed for detecting mitragynine in Mitragyna speciosa (kratom) using surface-enhanced Raman spectroscopy (SERS). Over 100 samples and blanks (known to be either positive or negative for the presence of mitragynine) were examined in duplicate using five identical handheld Raman spectrometers, which provided a data set of over 1,000 examinations. Based on the results of these analyses, the method yielded a true-positive rate of 99.3%, a true-negative rate of 97.9%, a false-positive rate of 2.1%, and a false-negative rate of 0.7%. The average minimum detectable concentration (Cm) of mitragynine that reproducibly yielded a match for one of the library spectra on all five instruments was determined to be 342 ng/mL (ppb). This Cm value is a conservative estimate considering that the extraction process was not fully optimized by this study, which was not necessary since the Cm value achieved was well below typical mitragynine concentrations in kratom (1.3–2.3%). The method is ideal (i) for prioritizing samples for additional testing using other more time-consuming laboratory-based techniques needed to detect and quantify mitragynine and (ii) for field use at international mail facility (IMF) satellite laboratories to help interdict kratom and prevent this dangerous product from reaching the U.S. supply chain. 相似文献
299.
Dalia M. Al-Saif M.B.B.S. S.B.F.L.M. Maram A. Al-Farayedhi M.B.B.S. S.B.F.L.M Ghadah A. Al-Shamsi M.B.B.S. S.B.F.L.M. Marwah I. Al-Bayat M.B.B.S. S.B.F.L.M. Osama M. Almadani M.D. Ph.D. F.F.F.L.M. Magdy A. Kharoshah M.B.Bch. M.Sc. M.D F.F.F.L.M. 《Journal of forensic sciences》2020,65(5):1574-1578
Examination of the female external genitalia to assess for sexual abuse is performed in living individuals, and the interpretation of the findings is based on evidence-based studies. However, in the deceased, no such studies are available, and postmortem changes could present as suspicious findings that can be mistaken for trauma. Patches of discoloration in the hymen were reported previously in one case as hypostasis (i.e., livor and lividity), and based on this finding, it was listed as a finding that is not associated with trauma. This was a retrospective study that was conducted in the Center of Forensic and Legal Medicine in Dammam, Saudi Arabia over a 4-year period. The study included 30 deceased women in whom photographic documentation of their external genitalia was assessed for postmortem changes. The postmortem interval ranged from less than 24 h to more than 100 days, and the ages of these deceased women were in the 20–40 year-old age group. In cases where the hymen, vagina, and/or fossa navicularis were clearly visible, none of these areas showed any hypostatic discoloration. A comparison between antemortem and postmortem appearance of the hymen in one case clearly showed the absence of hypostatic changes in the hymen. In conclusion, any discoloration of the external genitalia that is detected in a female decedent requires serious consideration. 相似文献
300.
Andrea Y. Garzón-Serrano M.Sc. César A. Sierra Ph.D. Oscar Rodríguez-Bejarano Dr.Sc. Diana Sinuco Dr.Sc. 《Journal of forensic sciences》2020,65(4):1085-1093
Ammonium nitrate fuel oil is an explosive mixture found in most antipersonnel landmines (APL) buried throughout the Colombian territory. During more than 50 years of internal conflict, the Colombian government has found that trained dogs are the most effective method to detect APL. However, the olfactive signature in ANFO is unknown and also if there are differences in detection related to the explosive manufacturing origin. Therefore, this work begins with the analytical validation of the method used to determine ammonia, in its derivatized form as carbamate, released by home-made ANFO using HS-SPME-GC-FID. Once validated, the method was used to identify ammonia and other organic volatile compounds present in ANFO, under laboratory and simulated field conditions. The validation process includes the evaluation of the optimum conditions for the derivation and extraction of butylcarbamate, the determination of the working ranges with linear response in FID, the limits of detection and quantification, the sensitivity, and the precision. The results of the validation established linearity and sensitivity in a concentration between 20 and 120 mg/L, as well as low limits of detection and quantification of 6.4 and 21.4 mg/L, respectively. Also, an intermediate precision of 11% for butylcarbamate with a repeatability of 8%. The validated method showed in real samples of home-made ANFO besides ammonia, the presence of low molecular methylamines, and also exhibited differences in volatile compositions according to the origin. The objective of this work is to offer a reliable analytical methodology for the extraction and analysis of volatile compounds from ANFO. 相似文献