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   6850篇
  免费   290篇
  国内免费   3篇
各国政治   369篇
工人农民   40篇
世界政治   935篇
外交国际关系   856篇
法律   2500篇
中国共产党   571篇
中国政治   905篇
政治理论   429篇
综合类   538篇
  2023年   45篇
  2022年   46篇
  2021年   32篇
  2020年   44篇
  2019年   64篇
  2018年   70篇
  2017年   17篇
  2016年   57篇
  2015年   51篇
  2014年   244篇
  2013年   180篇
  2012年   394篇
  2011年   411篇
  2010年   264篇
  2009年   208篇
  2008年   326篇
  2007年   335篇
  2006年   383篇
  2005年   353篇
  2004年   312篇
  2003年   319篇
  2002年   303篇
  2001年   251篇
  2000年   236篇
  1999年   172篇
  1998年   120篇
  1997年   111篇
  1996年   125篇
  1995年   142篇
  1994年   123篇
  1993年   71篇
  1992年   58篇
  1991年   67篇
  1990年   57篇
  1989年   66篇
  1988年   110篇
  1987年   91篇
  1986年   90篇
  1985年   96篇
  1984年   97篇
  1983年   102篇
  1982年   70篇
  1981年   61篇
  1980年   82篇
  1979年   42篇
  1977年   15篇
  1964年   24篇
  1962年   19篇
  1959年   19篇
  1957年   17篇
排序方式: 共有7143条查询结果,搜索用时 0 毫秒
251.
Allele and genotype frequencies for the ten STR loci D3S1358, VWA, D16S539, D2S1338, D8S1179, D21S11, D18S51, D19S433, TH01, FGA were determined in a Swiss Caucasian population sample (n=206) using the AmpFISTR SGM Plus Amplification kit. Electrophoresis was carried out on an ABI PRISM CE 310 Genetic Analyzer instrument. Previously, allele frequencies were published for the 13 STR loci D3S1358, VWA, FGA, D8S1179, D21S11, D18S51, D5S818, D13S317, D7S820, THO1, TPOX, CSF1PO and D16S539 for the same samples (n=206) amplified with the AmpFISTR Profiler Plus and Cofiler PCR Amplification kits. Since the results for the eight loci D3S1358, VWA, FGA, D8S1179, D21S11, D18S51, THO1, D16S539 shared between the AmpFISTR SGM Plus, Profiler Plus and Cofiler PCR Amplification kits already are published, only the allele frequencies for the two STR loci D2S1338 and D19S433 are reported in this paper. The two loci meet Hardy-Weinberg expectations. In addition, there is little evidence for association of alleles among the 15 loci (amplified with the Profiler, Cofiler, and SGM Plus amplification kits). The allelic frequency data can be used in forensic analyses to estimate the frequency of a multiple STR locus DNA profile in the Swiss population.  相似文献   
252.
A fast method using liquid-liquid extraction and HPLC/tandem-mass spectrometry (LC/MS/MS) was developed for the simultaneous detection of 11-Nor-Delta(9)-tetrahydrocannabinol-9-carboxylic acid beta-glucuronide (THC-COOH-glucuronide) and 11-Nor-Delta(9)-tetrahydrocannabinol-9-carboxylic acid (THC-COOH) in urine samples. This highly specific method, which combines chromatographic separation and MS/MS analysis, can be used for the confirmation of positive immunoassay results even without hydrolysis of the sample or derivatisation of extracts. Liquid-liquid extraction was optimised: with ethylacetate/diethylether (1:1, v/v) THC-COOH-glucuronide and THC-COOH could be extracted in one step. Molecular ions of the glucuronide (MH(+), m/z 521) and THC-COOH (MH(+), m/z 345) were generated using a PE/SCIEX turboionspray source in positive ionisation mode; specific fragmentation was performed in the collision cell of an API 365 triple-quadrupole mass spectrometer and yielded major fragments at m/z 345 (for THC-COOH-glucuronide) and m/z 327 as well as m/z 299 for both cannabinoids. Chromatographic separation was performed using a reversed-phase C8 column and gradient elution with 0.1% formic acid/1 mM ammonium formate and acetonitrile/0.1% formic acid. Retention times were 22.2 min for the glucuronide and 26.8 min for THC-COOH. After enzymatic hydrolysis of urine samples with beta-glucuronidase/arylsulfatase (37 degrees C, 5 h), THC-COOH-glucuronide was no longer detectable by LC/MS/MS in urine samples. However, the THC-COOH concentration was increased. For quantitation of THC-COOH, THC-COOH-D(3) was added to the urine samples as internal standard prior to analysis. From the difference of THC-COOH in the native urine and urine after enzymatic hydrolysis, molar concentration ratios of THC-COOH-glucuronide/THC-COOH in urine samples of cannabis users were determined and found to be between 1.3 and 4.5.  相似文献   
253.
In animal experiment and in cell culture, chronic morphine treatment has been followed by a reduction as well as an increase of the delta-opioid receptor (OR) number. The present postmortem morphometric study of morphine-related fatalities of drug addicts (n=12, 22-35 years old, with blood unconjugated morphine levels from 27.1 to 407 ng/ml, m.v. 176.9 ng/ml) versus a non-addicted control group (n=13, 10-44 years old) is intended to examine whether chronic opiate exposure also affects the numerical density of deltaOR expressing neurons in the human neocortex (area 10 according to Brodmann (Vergleichende Lokalisationslehre der Grosshirnrinde (1909) Johann Ambrosius Barth, Leipzig)). For the immunohistochemical procedure, vibratome sections (100 microm) were incubated with a monoclonal antibody against the deltaOR diluted 1:100, and immunoreactive sites were visualized using an immunoperoxidase protocol. The numerical densities of OR expressing and Nissl-stained neurons were assessed morphometrically (camera lucida drawings). In both collectives, the anti deltaOR immunoreactivity was predominantly localized in pyramidal neurons of layers (L) II/III and V as well as in round and ovoid neurons of L VI. In the drug-related fatalities, the density of neurons expressing deltaOR protein amounted for 2515+/-240/mm(3), in the control group for 2616+/-204/mm(3), thus displaying no statistically significant difference. These findings go along with the binding behavior of opioid ligands in postmortem brains of heroin addicts revealing similar receptor densities and affinities in the control subjects and addicts.  相似文献   
254.
In four forensic cases of unidentified skeletal remains investigated in the last year, we were able to attach three to missing persons. In one case we could show that the discovered bone sample did not fit to a missing child. The method for mitochondrial DNA analysis for the routine identification of skeletal remains was established in our institute by typing bone samples of defined age obtained from Frankfurt's cemetery. Reproducible results were obtained for bones up to 75 years old. For analysis the bone samples were pulverised to fine powder, decalcified and DNA was extracted. From the DNA we amplified a 404-bp fragment from HV-1 and a 379-bp fragment from HV-2 of the mtDNA control region. After sequencing of the PCR products, the results were compared to the Anderson reference sequence and to putative maternal relatives.  相似文献   
255.
256.
After years of debate, opinion among bioethicists and medical lawyers seems to have accepted that anticipatory refusals of medical treatment can, and furthermore should, be accorded the same legal status as contemporaneous refusals. But what would be the legal repercussions for a medic who treated an incompetent patient in contravention of such a directive? What remedies would be available to the claimant whose life had been extended contrary to his express wishes? This issue has never been explicitly addressed by the UK courts, but this paper looks at some of the conclusions and inferences we can perhaps draw from other, possible analogous areas of law. It also considers several North American cases that have addressed this issue, and asks what lessons we can learn therefrom.  相似文献   
257.
近几年来美国把对泰国援助中一部分“贈欵”改为貸欵,泰报认为是援助減少了。作者认为貸欵也是援助,但可能使泰国经济发展計划降低要求或中止,言外之音是希望增加“贈欵”。  相似文献   
258.
这是一篇替法帝国主义統治越南时期的少數民族政策辯护的文章。它把法帝国主义“分而治之”的反动政策說成是“善意好心”的,把法帝国主义所頒布的使越南泰族脫离越南,直接与法兰西联邦联系的法律,說成是符合民族特点和民族愿望的。它也透露了目前南越西原地区少數民族对吳庭艳集团的不滿,对越南民主共和国的民族政策的响往。但它却歪曲那些少數民族的意志,說他們热烈地怀念法国人。文章的观点是反动的,但可以看出帝国主义是如何欺騙当地少數民族的。  相似文献   
259.
自从1954年7月日内瓦协定订立之后,南越吴庭艶政府把土地改革存在关键性的问题,下了绝大的决心,付诸实施,特别是在土地转移和定居这两个方面。在实施土改计划上,美国的经济和技术援助起了重要的作用。土改计划的初步阶段,现在将近完成,減租和稳定佃期的计划,现在正在继续施行,并普及到全国佃农的3/4,而土地转移计划预  相似文献   
260.
英格兰姆在1951—52年,曾以“社会科学研究基金”名义,前往泰国进行調查工作。从泰国返美后,曾任美国北卡罗里那大学經济学教授。本文譯自著者:“1850年后泰国經济的变革”一書第三章,該章主要是分析1850至1950年以来泰国大米生产及輸出的情况。从文章內容可看出泰国經济,特別是农业生产的殖民地性和对外国資本的依賴性。  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