全文获取类型
收费全文 | 13136篇 |
免费 | 433篇 |
专业分类
各国政治 | 661篇 |
工人农民 | 566篇 |
世界政治 | 831篇 |
外交国际关系 | 385篇 |
法律 | 8234篇 |
中国共产党 | 4篇 |
中国政治 | 83篇 |
政治理论 | 2698篇 |
综合类 | 107篇 |
出版年
2020年 | 163篇 |
2019年 | 204篇 |
2018年 | 283篇 |
2017年 | 319篇 |
2016年 | 310篇 |
2015年 | 239篇 |
2014年 | 236篇 |
2013年 | 1410篇 |
2012年 | 355篇 |
2011年 | 336篇 |
2010年 | 287篇 |
2009年 | 305篇 |
2008年 | 379篇 |
2007年 | 347篇 |
2006年 | 373篇 |
2005年 | 336篇 |
2004年 | 347篇 |
2003年 | 310篇 |
2002年 | 316篇 |
2001年 | 428篇 |
2000年 | 411篇 |
1999年 | 308篇 |
1998年 | 183篇 |
1997年 | 170篇 |
1996年 | 149篇 |
1995年 | 152篇 |
1994年 | 143篇 |
1993年 | 157篇 |
1992年 | 268篇 |
1991年 | 276篇 |
1990年 | 269篇 |
1989年 | 259篇 |
1988年 | 239篇 |
1987年 | 255篇 |
1986年 | 273篇 |
1985年 | 264篇 |
1984年 | 224篇 |
1983年 | 238篇 |
1982年 | 145篇 |
1981年 | 137篇 |
1980年 | 116篇 |
1979年 | 150篇 |
1978年 | 128篇 |
1977年 | 105篇 |
1976年 | 93篇 |
1975年 | 104篇 |
1974年 | 118篇 |
1973年 | 115篇 |
1972年 | 100篇 |
1968年 | 80篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
991.
Grattapaglia D Schmidt AB Costa e Silva C Stringher C Fernandes AP Ferreira ME 《Forensic science international》2001,118(1):91-94
Allele frequencies for the 13 STR core loci (D3S1358, VWA, FGA, D8S1179, D21S11, D18S51, D5S818, D13S317, D7S820, CSF1PO, TPOX, THO1 and D16S539) included in the AmpFlSTR((R)) Profiler Plus and AmpFlSTR((R)) Cofiler kits were obtained for a sample of 700-800 genetically unrelated Brazilians. The expected performance of these loci for personal identification and paternity testing in the Brazilian population was estimated. 相似文献
992.
de Boer D Bosman IJ Hidvégi E Manzoni C Benkö AA dos Reys LJ Maes RA 《Forensic science international》2001,121(1-2):47-56
1-Aryl-piperazine compounds are, depending on their substituents, selective for certain serotonin receptors and together with their easy availability and their so-called legal status, this group of psychoactive compounds are potential designer drugs-of-abuse. Internet in that respect is an important source of information and distribution facilities. Because this development may have consequences for the interpretation of future clinical and forensic toxicological case studies, some analytical aspects of 1-benzyl-piperazine (BZP), 1-[4-methoxyphenyl]-piperazine (pMeOPP) and 1-[3-trifluoromethylphenyl]-piperazine (TFMPP) were studied. BZP was not detected by the AxSYM FPIA technology designed to determine amphetamine-like compounds, but had showed some cross reactivity with EMIT d.a.u.. The cross reactivities at 300 and 12,000ng/ml (RS)-amphetamine equivalents were 0.4 and 1.3%, respectively. Although BZP was not identified directly by the REMEDi HS Drug Profiling System, it can be detected by this HPLC/UV scanning system. Using GC/NPD without derivatisation, BZP, pMeOPP and TFMPP can be analysed for and applying GC/MS without or with acetylation or trifluoroacetylation, these compounds can be identified unambiguously. The usefulness of GC/NPD and GC/MS in this respect was demonstrated by the quantitative and qualitative analysis of the content of a capsule with the synthetic stimulant A2, which proved to contain 86.4mg of BZP. 相似文献
993.
Sensitive and specific multiresidue methods for the determination of pesticides of various classes in clinical and forensic toxicology 总被引:2,自引:0,他引:2
Lacassie E Marquet P Gaulier JM Dreyfuss MF Lachâtre G 《Forensic science international》2001,121(1-2):116-125
Original and sensitive multiresidue methods are presented for the detection and quantitation, in human biological matrices, of 61 pesticides of toxicological significance in human. These methods involved rapid solid-phase extraction using new polymeric support (HLB and MCX) OASIS cartridges. Gas chromatography-mass spectrometry (GC-MS) was used for volatile (organophosphate, organochlorine, phtalimide, uracil) pesticides and liquid chromatography-ionspray-mass spectrometry (LC-MS) for thermolabile and polar pesticides (carbamates, benzimidazoles). Acquisition was performed in the selected ion monitoring (SIM) mode. Extraction recovery varied owing to the nature of pesticides, but was satisfactory for all. Limits of detection (LODs) and limits of quantitation (LOQs) ranged, respectively, from 2.5 to 20 and from 5 to 50ng/ml. An excellent linearity was observed from LOQs up to 1000ng/ml for all the pesticides studied. The proposed procedures yielded reproducible results with good inter-assay accuracy and precision. A few cases of intoxication are presented to demonstrate the diagnostic interest of these methods: in two cases were determined lethal concentrations of endosulfan and carbofuran; in four other cases, the procedures helped diagnose intoxication with, respectively, parathion-ethyl, the association of bromacil and strychnine, bifenthrin and aldicarb. 相似文献
994.
Spectra interference between diquat and paraquat by second derivative spectrophotometry 总被引:1,自引:0,他引:1
A rapid and accurate method, combining solid-phase extraction and second-order derivative spectrophotomety approaches, is developed for the simultaneous determination of diquat (DQ) and paraquat (PQ) in blood, tissue and urine samples. Supernatant resulting from the precipitation of protein (with trichloroacetic acid) in plasma and tissue or Amberlite IRA-401 resin treated urine are passed through a mini-column packed with Wakogel gel (Silica gel). Analytes are then eluted with a non-organic solvent, 0.2mol/l HCl solution containing 2mol/l NH(4)Cl. UV spectrum of the eluent in 220-350nm range provides effective screen to detect the presence of DQ and/or PQ. In the presence of DQ or PQ alone, the analyte present is quantitated by conventional zero- or second-order derivative spectrophotometry. The calibration curve in the 0.1-5.0mg/l range for either analyte obeys Beer's law. When both DQ and PQ are present, their concentrations are determined by the peak amplitudes of their respective second-derivative spectra after the addition of alkaline dithionite reagent. Interference is negligible when the DQ/PQ concentration ratio is within the 5.0-0.2 range.Using a 2-ml of sample size, the detection limits for DQ and PQ in plasma are 0.02 and 0.005mg/l. The corresponding detection limits for urine samples (10ml sample size) are 0.004 and 0.001mg/l. Recoveries of DQ and PQ in triplicate plasma and urine samples spiked with 0.5mg/l of analytes are 93 and 85%. The precision of the proposed method resulting from triplicate study of spiked urine samples varies from 3.2 to 4.6% at 0.5mg/l of DQ and PQ, respectively. 相似文献
995.
Kankaanpää A Meririnne E Ellermaa S Ariniemi K Seppälä T 《Forensic science international》2001,121(1-2):57-64
The 4-methylaminorex (4-MAX) is an amphetamine-related psychostimulant drug that has appeared on the clandestine market with a street name of "U4Euh". This compound exists as four stereoisomers, trans-4R,5R, trans-4S,5S, cis-4R,5S and cis-4S,5R, of which the cis forms have been classified as Schedule I substances in the US. The increasing variety of designer drugs has highlighted the importance of detection, identification, and quantitative measurement of these drugs, including 4-MAX, in biological samples. In the present study, the isomers of 4-MAX were detected in urine of rats treated with the drugs by some but not all of the on-site immunoassays tested, mainly as amphetamine or methamphetamine. To facilitate identification of 4-MAX by laboratories specialized in drug analysis, the electron-ionization mass spectrum and TLC data for underivatized 4-MAX using a routine laboratory drug-screening procedure is provided. In addition, a GC/MS method is described for the quantitative determination of cis- and trans-4-MAX as tert-butyldimethylsilyl-derivatives in plasma, urine and tissue. 相似文献
996.
997.
998.
999.
This study examined the impact of types of women's verbal refusals, and the timing of her refusal, on men's discrimination of when a female wants her partner to stop making sexual advances. Male students were randomly assigned to 1 of 6 conditions (Explanations × Intimacy Levels). Before listening to an audiotape of a date rape, participants were told they would be listening to an interaction between a man and a woman who had just returned from a date. They were instructed to indicate when the woman wanted the man to stop making sexual advances by pressing a switch that synchronously stopped a timer (yielding the measure of latency). In the vignette, the woman provided an explanation for not engaging in sexual intercourse on the date either during kissing or when the man attempted to touch her breasts. She offered one of three reasons for refusing his sexual advances; fear of pregnancy, waiting until marriage, too early in the relationship. Results revealed an interaction in which participants in the too early in the relationship explanation at the level of breast contact condition displayed significantly longer latencies than individuals in the other groups. The implications of the findings are discussed. 相似文献
1000.