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   1270篇
  免费   120篇
  国内免费   343篇
安全科学   113篇
废物处理   55篇
环保管理   102篇
综合类   792篇
基础理论   229篇
污染及防治   286篇
评价与监测   52篇
社会与环境   53篇
灾害及防治   51篇
  2024年   5篇
  2023年   32篇
  2022年   69篇
  2021年   75篇
  2020年   73篇
  2019年   62篇
  2018年   66篇
  2017年   70篇
  2016年   68篇
  2015年   61篇
  2014年   93篇
  2013年   88篇
  2012年   107篇
  2011年   84篇
  2010年   104篇
  2009年   95篇
  2008年   89篇
  2007年   89篇
  2006年   68篇
  2005年   40篇
  2004年   31篇
  2003年   27篇
  2002年   28篇
  2001年   39篇
  2000年   36篇
  1999年   28篇
  1998年   19篇
  1997年   14篇
  1996年   16篇
  1995年   10篇
  1994年   22篇
  1993年   10篇
  1992年   4篇
  1991年   1篇
  1990年   2篇
  1989年   2篇
  1988年   4篇
  1987年   1篇
  1979年   1篇
排序方式: 共有1733条查询结果,搜索用时 31 毫秒
121.
提高高校档案利用的新途径   总被引:1,自引:0,他引:1  
针对目前高校档案利用率不高的实际情况,为有效地提高档案利用率,充分发挥高校档案在高校发展建设、科学管理、提升教育教学水平中的作用,笔者通过多年的探索实践,提出了加大宣传力度、搞好基础建设、提高人员素质、拓展服务方式、创新服务内容等高校档案利用的新途径,与从事高校档案工作的广大同仁商榷。  相似文献   
122.
论焦化行业环境风险防范措施及应急预案   总被引:2,自引:0,他引:2  
本文对焦化行业的原辅材料及产品的理化性质、生产过程中潜在的环境风险进行了识别,并在此基础上有针对性的提出了焦化行业环境风险防范措施及应急预案。  相似文献   
123.
The thermoplastic starch (TPS) and nanocomposite(TPS/OMMT) was prepared with 15% carbamide, 15% ethanolamine and different contents of organic activated montmorillonite (OMMT) by twin-screw extruder with a 130 °C barrel temperature. Fourier transforms infrared spectroscopy and wide angle X-ray diffraction shown that the alkylamine in dodecyl benzyl dimethyl ammonium bromide could react with MMT via cation exchange reaction. After treated, the d(001)space distance of MMT increased from 1.5 to 1.7 nm. Scanning electron microscope revealed that the lower contents of OMMT could disperse well in the matrixes of TPS. The carbamide, ethanolamine and the OMMT could destroy the crystallization behavior of starch, but only the OMMT restrained this behavior for long-term storing. Mechanical properties investigation indicated that the tensile strength and modulus of TPS/OMMT nanocomposites were better than those of TPS, while the elongation at break was descended with the increasing of OMMT contents. When the content of OMMT was 4%, the tensile strength and modulus of TPS was improved from 4.2 and 42 MPa to 6.0 and 76 MPa, respectively.  相似文献   
124.
研究了阴离子表面活性剂水溶液的紫外吸收特性,并将研究结果用于阴离子表面活性剂水质标样的稳定性,均匀性和定值工作,简化了操作手续,获得了准确的分析结果。  相似文献   
125.
To evaluate boron contamination of public drinking water in China, both dissolved and total boron contents in 98 public drinking water sources from 49 cities, 42 brands of bottled water samples from supermarkets in several cities, and 58 water samples from boron industrial area were measured by inductively coupled plasma-mass spectrometry (ICP-MS). Our experimental results showed that boron existed in public drinking water sources mainly in dissolved status with total concentrations ranging from 0.003 to 0.337 mg/L (mean = 0.046 mg/L). The mean boron concentrations in mineral and pure bottled water were 0.052 and 0.028 mg/L, respectively. The results obtained in this work showed that there was no health risk on view of boron in public drinking water sources and bottled water. In boron industrial area, boron concentrations in surface water and ground water were 1.28 mg/L (range = 0.007–3.8 mg/L) and 18.3 mg/L (range = 0.015–140 mg/L), respectively, which indicated that boron industry caused boron pollution in local water system.  相似文献   
126.
Wang X  Cook R  Tao S  Xing B 《Chemosphere》2007,66(8):1476-1484
Sorption behavior of hydrophobic organic contaminants (HOCs) (i.e., pyrene, phenanthrene and naphthalene) by native and chemically modified biopolymers (lignin, chitin and cellulose) was examined. Lignins (native and treated) showed nonlinear sorption for all compounds studied, emphasizing their glassy character. Chitins and celluloses had linear isotherms for phenanthrene and naphthalene, illustrating the dominance of partitioning, while pyrene yielded nonlinear isotherms. Sorption capacity (K(oc)) of HOCs was negatively correlated with the polarity [(O+N)/C] of the biopolymers. Aromatic and alkyl+aromatic C percentages, rather than alkyl C content, demonstrated a better correlation with K(oc) values, indicating the importance of aromatic structures for HOC affinity. Hydrophobicity (K(ow))-normalized K(oc) values decreased sharply with increasing percentage of O-alkyl C versus total aliphatic C (O-alkyl C/total aliphatic C) or with polar C/(alkyl+aromatic C) ratio of the biopolymers until their values reached 80% and 4, respectively, illustrating the effect of surrounding polar groups on reducing affinity for HOCs. Overall, the results of this study highlight the role of spatial arrangement of domains within biopolymers in sorption of HOCs, and point to sorbent properties, such as functionality, polarity and structure, jointly regulating the sorption of HOCs in biopolymers.  相似文献   
127.
建筑物消防系统可靠性分析   总被引:1,自引:1,他引:0  
为评估建筑物消防系统的可靠性,首先将系统分为探测报警系统和灭火系统等部分,再用事件树法分析事故发生时消防系统不同部分的反应情况.通过贝叶斯理论及历史统计数据得到系统失效率的不确定性概率分布,建立消防系统可靠性随时间变化的数学模型; 用蒙特卡罗方法模拟求得系统可靠性的时间函数并对模型的不确定性参数进行敏感性分析.该方法将统计数据与经验公式、理论方法相结合,并利用蒙特卡罗方法处理模型中的不确定性,不仅能够有效估计消防系统的可靠性,还可对其他类似系统的可靠性进行分析,并通过敏感性分析为进一步减少估计的不确定性提出合理建议.  相似文献   
128.
多米诺效应的风险分析方法   总被引:2,自引:0,他引:2  
介绍与分析多米诺效应的相关研究,并针对多米诺效应的定量风险分析,建立了从多米诺场景辨识到后果分析的多米诺效应定量分析方法.通过分析初始事故带来的物理效应对邻近设备的影响,计算了二次设备的损坏概率;分析了多米诺场景,计算了多米诺事故频率,并根据多米诺事故的后果得到个人风险和社会风险曲线.多米诺效应的风险是工业区一个潜在的严重风险,加强多米诺效应的研究对工厂和工业区的安全管理与规划都有重要意义.  相似文献   
129.

Problem

The aims of the study were to evaluate information on motor-vehicle crashes with injuries provided in newspaper reports and to assess the frequency of thematic and episodic reporting of motor-vehicle crashes.

Method

The study used Fatal Analysis Reporting System (FARS) derived variables to code a nationally representative sample of U.S. newspaper reports of motor-vehicle crashes from 1999-2002. A total of 473 newspaper reports of motor-vehicle crashes with injuries were included. Information on the crash event, people involved, and vehicles was extracted. The reports were coded for episodic and thematic news framing.

Results

A majority of newspaper reports used episodic framing. The majority of reports included information on the type of crash, but characteristics about people and vehicles were rarely reported.

Discussion

Lack of information in newspapers makes them an incomplete source from which to influence public perceptions and attitudes.

Impact on industry

This provides an opportunity for news print media to improve public health content.

Impact on industry

Newspapers represent an important source of public information; they are, however, an incomplete source [Voight, B., Lapidus, G., Zavoski, R., & Banco, L. (1998). Injury reporting in Connecticut newspapers. Injury Prevention, 4, 292-294.; Baullinger, J., Quan, L., Bennett, E., Cummings, P., & Williams, K. (2001). Use of Washington state newspaper for submersion injury surveillance. Injury Prevention, 7, 339-342]. To increase the accuracy of information provided to the public through media sources, there is a need for increased communication between public health professionals and reporters.The results of this study raise concerns about the contents of motor-vehicle crash information provided in newspapers and suggest that newspapers do not provide information to allow public perception to be in accord with the importance of motor-vehicle crash injuries and health promoting actions to reduce risk of injury. More balanced and detailed information in newspapers would provide an opportunity for news print media to improve public health programs and public perception about the impact of motor-vehicle crashes on safety for all.  相似文献   
130.
PROBLEM: Unsafe driving and passenger behaviors place teens at increased risk for fatal and nonfatal crashes. This study evaluated the short-and long-term efficacy of the You Hold the Key (YHTK) Teen Driving Countermeasure. METHOD: A two-page survey was completed by high school students at pretest, posttest, and long-term (6-month) posttest. RESULTS: YHTK was associated with significant immediate and long-term improvements in teen seatbelt use, safe driving, and perceived confidence in preventing drunk driving. Compared to pretests, students at immediate and long-term posttest more frequently wore seatbelts when driving or riding, required passengers to wear seatbelts, and limited the number of passengers to the number of seatbelts in the vehicle. Students were more likely at both posttests to avoid drinking and driving and to say no to riding with a friend who had been drinking. SUMMARY: YHTK was associated with increases in safe teen driving and passenger behaviors. IMPACT ON INDUSTRY: Success of YHTK is most notably due to its comprehensive nature. Future programs should consider comprehensive strategies when attempting to modify teen behaviors.  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