首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   169篇
  免费   6篇
各国政治   11篇
工人农民   10篇
世界政治   7篇
外交国际关系   2篇
法律   102篇
中国政治   1篇
政治理论   42篇
  2023年   2篇
  2022年   1篇
  2021年   2篇
  2020年   6篇
  2019年   9篇
  2018年   9篇
  2017年   6篇
  2016年   15篇
  2015年   10篇
  2014年   1篇
  2013年   22篇
  2012年   8篇
  2011年   7篇
  2010年   5篇
  2009年   9篇
  2008年   4篇
  2007年   5篇
  2006年   10篇
  2005年   10篇
  2004年   4篇
  2003年   6篇
  1999年   3篇
  1998年   3篇
  1997年   2篇
  1996年   1篇
  1995年   1篇
  1994年   2篇
  1993年   1篇
  1991年   1篇
  1988年   4篇
  1987年   2篇
  1986年   2篇
  1985年   1篇
  1970年   1篇
排序方式: 共有175条查询结果,搜索用时 15 毫秒
161.
In the present study, we demonstrate that two commonly used Y-chromosome single nucleotide polymorphisms (SNPs), P25 and 92R7, are paralogous sequence variants (PSVs) originating from segmental duplications and that at least one of the sequence variants in each group of loci is polymorphic. Several methodologies were used in order to detect the SNP alleles and the PSVs of the loci. All results obtained with the various typing techniques supported the conclusion. The allele distributions of the binary markers were analysed in more than 600 males with seven different haplogroups. For P25, the ancestral allele C was found in several samples from different haplogroups. The derived allele A was always present with an additional C variant. Haplogroup P was defined by the derived allele A at the 92R7 locus. However, the ancestral allele G was always associated with an A variant due to the duplication.  相似文献   
162.
163.
164.
Abstract. The purpose of this paper is to estimate popularity functions for the Portuguese Prime Minister, Government, Parliament and President using the ordinary least squares (OLS) and seemingly unrelated regressions (SUR) methods. The results indicate that: (1) popularity polls for the Prime Minister and Government are better explained by economic conditions than are similar polls for the Parliament and President; (2) unemployment is a significant variable determining popularity while inflation is not; (3) honeymoon effects are significant; (4) popularity deteriorates over consecutive terms.  相似文献   
165.
This study examined the impact of three program-level factors (coercion level, type of antipsychotic prescribed, and guardian supervision) on antipsychotic medication adherence among parolees mandated to an outpatient psychiatric clinic. Overall, 70.7% of the participants tested positive for their prescribed antipsychotic. Older patients were more likely to test positive for their prescribed antipsychotic than younger patients, and African American patients (relative to all other race/ethnic groups) were less likely. With regard to program-level factors, perceived coercion was not significantly associated with medication adherence. However, being prescribed an atypical antipsychotic and having a guardian were independently associated with increased adherence, and combined, these two factors were associated with nearly a tenfold increase in the likelihood of patients testing positive for their prescribed antipsychotic agent, relative to patients who were prescribed conventional antipsychotics and were not under guardian supervision.  相似文献   
166.
167.
Robotic extraction of DNA from dilutions of blood and semen using either the BioRobots EZ1 or BioRobots M48 consistently produced lower recoveries than standard organic extractions of the same samples. In an effort to increase the efficiency of robotically extracted DNA, glycogen and carrier RNA were added following cell lysis. The addition of glycogen, postlysis, resulted in no improvement in DNA recovery with the BioRobot EZ1. However, when carrier RNA was added to the cell lysate of limited and degraded samples extracted on the EZ1 or the M48, DNA recoveries dramatically increased four- to 20-fold. DNA yields obtained by robotic extraction in the presence of carrier RNA were as high, or higher, as those obtained by organic extraction lacking carrier RNA, while experiments that utilized carrier RNA in both types of extractions showed increased sensitivity for both methods. Furthermore, carrier RNA substantially increased the recovery of fragmented DNA with the EZ1.  相似文献   
168.
1,4-Dihydropyridines calcium channel antagonists (1,4-DHP CCAs) are photolabile and the products of their photodecomposition have no pharmaceutical activity. In our previous work we have presented a screening procedure for eleven 1,4-DHPs in plasma by LC-MS-MS using multiple reaction motoring. The laboratory process includes preparation and storage of stock solutions, plasma storage, solid-phase extraction, reconstitution of extracts and storage time in an autosampler for LC-MS-MS analysis. Prior to validation of the analytical procedure, we have tested the stability of these compounds by exposure to light. Methanolic solutions have been exposed to laboratory and UV light and the stability of the compounds in plasma was tested by exposure of spiked plasma samples to laboratory light at room temperature. Stability during freeze-thaw cycles and stability during 2 month storage at -20 degrees C have been tested as well. Products of photodecomposition have been identified after forced degradation and the degree of degradation has been quantified using LC-UV-DAD and LC-MS-MS, respectively. A 96% degradation after only 2h has been observed when solutions of nifedipine or nisoldipine were exposed to laboratory light in clear glass vials. In plasma samples degradation was 25% in only 2h for both compounds. The main degradation product was produced by oxidation of the dihydropyridinic ring resulting in the pyridine analogue that has been described as the first metabolite in the metabolic pathway. Only minor degradation was found for the other tested compounds after 2h light exposure in methanolic solutions. Furthermore, lercanidipine and nicardipine were also degradated by esterhydrolysis. Several additional minor degradation products were found for the other tested 1,4-DHPs, however, some of them could not be identified. Preconditions for storage and handling of plasma samples prior to and during analysis for 1,4-DHP CCAs are suggested in order to avoid photodecomposition of the analytes.  相似文献   
169.
A collaborative study was carried out by the European DNA Profiling Group (EDNAP) in order to evaluate the performance of Y-chromosome binary polymorphism analysis in different European laboratories. Four blood samples were sent to the laboratories, to be analysed for 11 Y-chromosome single nucleotide polymorphisms (SNPs): SRY-1532, M40, M35, M213, M9, 92R7, M17, P25, M18, M153 and M167. All the labs were also asked to submit a population study including these markers. All participating laboratories reported the same results, indicating the reproducibility and robustness of Y-chromosome SNP typing. A total of 535 samples from six different European populations were also analysed. In Galicia (NW Spain) and Belgium, the most frequent haplogroup was R1b*(xR1b1,R1b3df). Haplogroup F*(xK) is one of the most frequent in Austria and Denmark, while the lowest frequency appear in Belgium. Haplogroup frequencies found in this collaborative study were compared with previously published European Y-chromosome haplogroup data.  相似文献   
170.
The Brazilian polymer industry (plastics, rubbers, fibers, adhesives, paints, and varnishes) is the fastest growing segment of the Petrochemical Chain. Since the polymer industry is characterized as science based, the capacity to create technology is vital for its long-range survival in the market. This paper analyzes how Brazilian polymer firms maintain their technological competitiveness, explains the main modes of technology transfer, and evaluates the degree of technological dependence of this industry. The methodology consisted of a database built with data from the Brazilian Patent Office. To confirm the findings, interviews were conducted with staff members from seven Brazilian polymer firms. The data base analysis and the interviews reveal that, in spite of the fact that Research and Development (R&D) and technological innovation have a fundamental role in their competitiveness, the firms are technologically dependent upon foreign suppliers.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号