全文获取类型
收费全文 | 16944篇 |
免费 | 496篇 |
专业分类
各国政治 | 694篇 |
工人农民 | 660篇 |
世界政治 | 1412篇 |
外交国际关系 | 581篇 |
法律 | 10201篇 |
中国共产党 | 2篇 |
中国政治 | 75篇 |
政治理论 | 3642篇 |
综合类 | 173篇 |
出版年
2020年 | 208篇 |
2019年 | 247篇 |
2018年 | 321篇 |
2017年 | 385篇 |
2016年 | 411篇 |
2015年 | 286篇 |
2014年 | 330篇 |
2013年 | 1643篇 |
2012年 | 402篇 |
2011年 | 425篇 |
2010年 | 339篇 |
2009年 | 377篇 |
2008年 | 438篇 |
2007年 | 458篇 |
2006年 | 438篇 |
2005年 | 388篇 |
2004年 | 392篇 |
2003年 | 414篇 |
2002年 | 375篇 |
2001年 | 676篇 |
2000年 | 614篇 |
1999年 | 504篇 |
1998年 | 283篇 |
1997年 | 241篇 |
1996年 | 202篇 |
1995年 | 204篇 |
1994年 | 243篇 |
1993年 | 218篇 |
1992年 | 335篇 |
1991年 | 367篇 |
1990年 | 325篇 |
1989年 | 343篇 |
1988年 | 315篇 |
1987年 | 332篇 |
1986年 | 336篇 |
1985年 | 330篇 |
1984年 | 284篇 |
1983年 | 316篇 |
1982年 | 254篇 |
1981年 | 237篇 |
1980年 | 178篇 |
1979年 | 246篇 |
1978年 | 165篇 |
1977年 | 144篇 |
1976年 | 130篇 |
1975年 | 120篇 |
1974年 | 135篇 |
1973年 | 117篇 |
1972年 | 112篇 |
1971年 | 94篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
901.
Six ninhydrin analogues containing oxygen, sulfur, and selenium substituents at the C-5 position, 5-(4-nitrophenyl)ninhydrin, and benzo[f]furoninhydrin were evaluated as fingerprint development reagents. The analogues all showed good fingerprint color development but were not superior to ninhydrin in this respect. The benzo[f]furoninhydrin complex was strongly luminescent at room temperature following zinc complexation, while the remaining analogues required cooling to -196 degrees C to produce optimum luminescence. The benzo[f]furo, nitrophenyl, and methyl selenide analogues showed the best potential as fingerprint reagents with the benzo[f]furo analogue comparing favorably with DFO. 相似文献
902.
Antitrust law represents the principal legal tool that the United States employs to police private markets, yet it often relegates quality and nonprice considerations to a secondary position. While antitrust law espouses the belief that vigorous competition will enhance quality as well as price, little evidence exists of the practical ability of courts to deliver on that promise. In this Article, Professors Hammer and Sage examine American health care as a vehicle for advancing understanding of the nexus among competition, quality, and antitrust law. The Article reports results of a comprehensive empirical review of judicial opinions in health care antitrust litigation between 1985 and 1999, with specific attention to courts' handling of quality and other nonprice concerns. Professors Hammer and Sage conclude that, although antitrust law cannot be expected to serve as the sole oversight mechanism for industries as complex and quality dependent as health care, courts have been successful incorporating some nonprice factors into antitrust analysis. 相似文献
903.
904.
905.
906.
Bile is, in certain cases, collected together with blood from different sites (heart, brain, femoral), urine and other organs or matrices. This study reports comparative results obtained from the analysis of blood and bile for different drugs found: acetaminophen, amphetamine and related compounds, several antidepressants, several benzodiazepines, cocaine and its metabolites, dextropropoxyphene and its metabolite, hydroxyzine, methadone and metabolite, morphine and codeine, levomepromazine, thioridazine, propranolol, tramadol and its metabolite. Several findings are presented: (1) There were no significant differences in the levels of the compounds among the samples of blood obtained from different sites. (2) Levels in bile are generally several fold higher than those in blood. The mean bile to blood ratios vary from about 1 (for acetaminophen, amphetamine) to about 2000 (for desmethylclobazam). (3) In certain cases (16 over 44), although the drug or its metabolite was not detected in blood from different sites, it was detected in bile. As other authors had advocated, it is very useful to ask the pathologist to take the gall bladder with its contents together with the other samples, in order that the sample of bile can be used in the comprehensive toxicological analysis and therefore be complementary to the other fluids or matrices. An additional advantage for using bile is that the concentrations of drugs or their metabolites are generally several fold higher than their blood concentrations. 相似文献
907.
Samyn N De Boeck G Wood M Lamers CT De Waard D Brookhuis KA Verstraete AG Riedel WJ 《Forensic science international》2002,128(1-2):90-97
In a double-blind placebo controlled study on psychomotor skills important for car driving (Study 1), a 75 mg dose of +/- 3,4-methylenedioxymethamphetamine (MDMA) was administered orally to 12 healthy volunteers who were known to be recreational MDMA-users. Toxicokinetic data were gathered by analysis of blood, urine, oral fluid and sweat wipes collected during the first 5h after administration. Resultant plasma concentrations varied from 21 to 295 ng/ml, with an average peak concentration of 178 ng/ml observed between 2 and 4h after administration. MDA concentrations never exceeded 20 ng/ml. Corresponding MDMA concentrations in oral fluid, as measured with a specific LC-MS/MS method (which required only 50 microl of oral fluid), generally exceeded those in plasma and peaked at an average concentration of 1215 ng/ml. A substantial intra- and inter-subject variability was observed with this matrix, and values ranged from 50 to 6982 ng/ml MDMA. Somewhat surprisingly, even 4-5h after ingestion, the MDMA levels in sweat only averaged 25 ng/wipe. In addition to this controlled study, data were collected from 19 MDMA-users who participated in a driving simulator study (Study 2), comparing sober non-drug conditions with MDMA-only and multiple drug use conditions. In this particular study, urine samples were used for general drug screening and oral fluid was collected as an alternative to blood sampling. Analysis of oral fluid samples by LC-MS/MS revealed an average MDMA/MDEA concentration of 1121 ng/ml in the MDMA-only condition, with large inter-subject variability. This was also the case in the multiple drug condition, where generally, significantly higher concentrations of MDMA, MDEA and/or amphetamine were detected in the oral fluid samples. Urine screening revealed the presence of combinations such as MDMA, MDEA, amph, cannabis, cocaine, LSD and psilocine in the multiple-drug condition. 相似文献
908.
Allele frequencies for the three STR loci included in the GenePrint CTT multiplex system (HUMTH01, HUMTPOX, HUMCSF1PO) have been determined for the four major sub-populations of New Zealand. 相似文献
909.
Petra M. van de Looij-Jansen Judith E. J. Goldschmeding Erik Jan de Wilde 《Journal of youth and adolescence》2006,35(4):652-658
Self-report questionnaires are frequently used in youth research, but doubt remains whether total anonymity affects the results. This study compared the responses of 704 mainly 16–17-year-old adolescents to self-report measures of various health indicators in 2 groups: anonymous and confidential collection. For most health indicators no significant differences were found. Perceived health, use of alcohol, and aggressive behavior (for boys) were reported significantly less frequently in the confidential group (small effect size). It appeared that pupils with high scores on social desirability do not respond differently at most health indicators in the 2 conditions. For most health characteristics, epidemiologically useful outcomes may be derived from confidential self-report measures, which are also valuable for detecting individual at-risk children. Similar studies in lower grades and other types of education should confirm the results.Youth Department, Municipal Health Service Rotterdam area. Main research interests are emotional and behavioral problems of adolescents, youth health care, monitoring.Youth Department, Municipal Health Service Rotterdam area. Main research interests are emotional and behavioral problems of adolescents, youth health care, monitoring.Research Department, Municipal Health Service Rotterdam area. Major research interests include emotional and behavioral problems of adolescents, suicidal behavior, youth health care, monitoring. 相似文献
910.
Christie J. Rizzo Shannon E. Daley Brent H. Gunderson 《Journal of youth and adolescence》2006,35(3):444-453
The role of interpersonal sensitivity in the relation between romantic stress and depression was examined in 55 adolescent girls from an inner-city high school. Depression, interpersonal sensitivity, and chronic and episodic romantic stress were measured at two time points, 6 months apart. Interpersonal sensitivity was found to moderate the longitudinal relation between romantic stress (both chronic and episodic) and depression. In contrast, interpersonal sensitivity did not potentiate depressive responses to non-romantic interpersonal stress, suggesting particular importance of stress in the romantic domain for adolescent girls. Results indicate that girls' sensitivities to romantic relationship stress should be specifically addressed in depression prevention and intervention programs.Received her PhD from the University of Southern California. Research interests include the influence of romantic relationship factors, such as romantic stress and dating violence, on the development of depression during adolescence.Received her PhD from the University of California, Los Angeles. Research interests include the interplay between adolescent depression, personality disorder symptoms, and interpersonal variables including adjustment in friendships and romantic relationships.Research interests include cognitive and interpersonal factors in adolescent depression. 相似文献