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   1500篇
  免费   80篇
各国政治   103篇
工人农民   36篇
世界政治   79篇
外交国际关系   112篇
法律   892篇
中国共产党   3篇
中国政治   56篇
政治理论   182篇
综合类   117篇
  2024年   4篇
  2023年   19篇
  2022年   18篇
  2021年   29篇
  2020年   47篇
  2019年   42篇
  2018年   56篇
  2017年   85篇
  2016年   51篇
  2015年   40篇
  2014年   90篇
  2013年   208篇
  2012年   90篇
  2011年   68篇
  2010年   82篇
  2009年   104篇
  2008年   85篇
  2007年   95篇
  2006年   81篇
  2005年   37篇
  2004年   49篇
  2003年   41篇
  2002年   42篇
  2001年   31篇
  2000年   15篇
  1999年   15篇
  1998年   8篇
  1997年   3篇
  1996年   4篇
  1995年   4篇
  1994年   3篇
  1993年   4篇
  1992年   3篇
  1991年   4篇
  1990年   3篇
  1989年   3篇
  1988年   2篇
  1987年   2篇
  1986年   1篇
  1985年   2篇
  1984年   3篇
  1983年   2篇
  1982年   2篇
  1981年   3篇
排序方式: 共有1580条查询结果,搜索用时 31 毫秒
41.
The global proliferation of precision-strike systems may be challenging the foundations of Western military-technological supremacy. Relatedly, the development of so-called Anti-Access and Area Denial (A2/AD) capabilities across the globe threatens to complicate Western freedom of military movement and access, and could give way to a more contested military-strategic environment. The twin challenges of precision-strike proliferation and A2/AD strongly impact NATO’s agenda, which revolves around strengthening deterrence and defence in Eastern Europe, and addressing the different threats emanating from the so-called Southern European neighbourhood. In order to address or mitigate such challenges, the Alliance needs to produce operational concepts and capabilities able to deliver deterrence and expeditionary warfare in a maturing precision-strike environment, one characterised by the emergence of A2/AD capabilities.  相似文献   
42.
There is strong evidence that land use regulations constrain housing production. We know less about how real estate developers respond to specific zoning provisions. I compare the characteristics of new multifamily housing with baseline land use regulations in two sets of rail station areas in Los Angeles. I supplement this building-scale analysis with expert interviews. I find that developers were most sensitive to density restrictions and parking requirements. The average development in the Vermont/Western area had 112% of the maximum allowable residential density and 94% of the minimum required parking. Koreatown’s average development had 99% of the maximum density and 88% of the required parking. But, there was variation by area and whether a building was affordable or market rate, apartment or condominium, and by development size. Additionally, regulatory implementation can matter as much as the written regulations themselves. I recommend that cities take an evidence-based approach to reforming regulations and implementation processes.  相似文献   
43.
目的 观察脑络欣通对大脑中动脉阻塞再灌注(middle cerebral artery occlusion-reperfusion,MCAO-R)模型大鼠神经干细胞增殖分化的影响。方法 采用线栓法复制MCAO-R大鼠模型,将30只健康雄性SD大鼠随机分成假手术组、模型组和给药组。分别采用神经功能评分和TTC染色鉴定模型大鼠的神经功能缺损和脑缺血面积,采用免疫荧光染色法观察大鼠海马CA1、CA2、CA3、齿状回(dentate gyrus,DG)区巢蛋白(Nestin)和神经丝蛋白-H(hypophosphorylated neurofilament-H,NF-H)表达水平。结果 给药组Nestin阳性表达主要发生在DG区,NF-H阳性表达主要发生在CA3区。脑络欣通促进神经干细胞增殖的作用在DG、CA1、CA2、CA3区均十分明显,以DG区尤为突出,促进神经干细胞分化的作用主要表现在CA3、DG、CA2、CA1区。与模型组比较,给药组大鼠海马各区的Nestin、NF-H阳性细胞均明显增多,差异具有统计学意义(P<0.05)。结论 脑络欣通具有促进海马区神经干细胞增殖并分化为神经细胞的作用。  相似文献   
44.
Faced with pressing climatic changes, scientific and industrial interests are vying to develop crops that can survive drought, floods and shifting pest regimes. Increasingly, they look for solutions in an unlikely place: the gene pools of wild plants. Crop wild relatives (CWR) – species closely related to crops, including their ancestors – offer breeders the allure of retracing the domestication bottleneck, infusing genomes of modern crops with ‘lost’ genetic variety. Yet wild relatives also confront threats from climate change, urbanization and expansion of industrial agri-food. Thus, CWR, seen as both salvational and threatened, have become an international conservation and food-security priority. It is my contention that, in their common project to harness wild-relative potential, conservation and breeding science are co-evolving to extend seed commodity relations into new spheres. I examine enclosures along two fronts: first within ‘systematic CWR conservation’, where ‘in situ’ approaches, typically regarded as empowering and sustainable alternatives to ‘ex situ’, instead may support a complementary system of value extraction; second, in breeding and biotechnology research, which produces new value for CWR while profoundly shaping upstream conservation priorities. An important finding is that although today’s ‘ex situ-centric’ complementarity favors dispossession, an ‘in situ-centric’ approach could foster democratic renewal of biocultural diversity.  相似文献   
45.
ABSTRACT

There are various intermediaries bearing witness to distant conflicts and atrocities. They travel to distant parts of the world to collect different kinds of evidence and stories, motivated by the assumption that knowledge can evoke change. This article asks how authenticity is claimed in this context of humanitarian witnessing. It focuses on two, at first sight quite different, practices of representation: NGO human rights reporting and comics journalism, also known as graphic reporting. It argues that representations of first-hand access to sites and people involved in abuses, or of ‘having been there’, figure centrally in establishing authenticity and thereby truth. The article discusses two techniques through which first-hand truth claims are performed: representations of field research methodologies, and personifications of truth in the figure of the witness. The intermediaries chosen for an in-depth study are the human rights NGO Human Rights Watch and the US comics journalist Joe Sacco.  相似文献   
46.
Since the 1980s, the so-called “nomadic” populations in the regions of Northern Mali and Niger have embarked on an extensive process of settlement. Today they mostly live in villages or “settlement sites”. But, at the same time, individuals and small groups among these same populations have considerably enlarged their area of mobility and accelerated the rate and the value of the trade in which they engage. These two phenomena could, at first sight, appear contradictory. But the observation of empirical situations shows, rather, compatibilities, similarities even, between these two concomitant phenomena. Building on innovative debates conducted in geography and sociology, this article puts forward the hypothesis that the building of villages, as well as integration into military bases and barracks, proceeds from (social) rationales of mobility, just as much as transhumance, journeys, migration. Much more than a simple displacement in space, the notion of mobility could describe an “art of doing”, a way of being to others and to the world.  相似文献   
47.
《鹿特丹规则》对无单放货问题设计了新的解决机制,通过使特定条件下的无单放货合法化,试图减轻承运人的负担,平衡船货双方的利益。采取规范分析的方法,对这一机制进行解构,论述其给各当事方的法律地位所带来的变化,认为对现有制度进行改良可能是更好的选择。  相似文献   
48.
目的 研发海洛因标准品及优化分析方法,以对云南缴获海洛因样本提纯制备成的自制海洛因对照品在常用有机溶剂中的稳定性进一步研究.方法 采用内标及GC、GC/MS方法,通过对提纯制备的海洛因在5种有机溶剂中冷藏保存后含量的变化,观察海洛因在常用有机溶剂中的稳定性.结果 乙醇、三氯甲烷及乙腈为溶剂的自制海洛因对照品储备液,保存30天时间范围内海洛因含量未发生明显变化;以丙酮作为溶剂的自制海洛因对照品储备液,在7至30天时间范围内,海洛因含量明显升高;以甲醇作为溶剂的自制海洛因对照品储备液,在0小时至30天时间范围内,海洛因含量一直呈明显的下降趋势.结论 乙醇、三氯甲烷及乙腈可以作为海洛因样品储备液溶剂使用,丙酮、甲醇不适合作为海洛因样品储备液溶剂使用.  相似文献   
49.
一 1 9岁男子赌气吞服一白色粉末 ,1 0min后口鼻流血、抽搐 ,迅速送医院 ,经催吐、透析等方法治疗 5天后死亡。根据中毒症状和经验怀疑为毒鼠强中毒。用GC/NPD检验肝中毒鼠强有干扰。改用GC/MS -SIM法分析 ,心血、肝和胃组织中全部检出毒鼠强 ,浓度分别为 0 5 1 μg .mL- 1、0 4 5 μg .g- 1和 0 33μg .g- 1,和文献结果在同一水平。GC/MS -SIM对复杂检材中低含量毒鼠强测定具有更高的选择性 ,也具有较高的灵敏度 ,同时进一步证实毒鼠强排泄较慢 ,经过较长时间后在体内分布比较均匀  相似文献   
50.
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