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排序方式: 共有51条查询结果,搜索用时 31 毫秒
21.
利用生命周期评价工具对煤基M100和FTD作为车用替代燃料生命周期环境影响进行评价。结果表明:温室效应和不可再生资源消耗为两种燃料生命周期产生最主要环境影响。与M100相比,相同功能单位FTD环境影响总水平值略高。通过敏感性分析,建议综合利用CO2捕集技术等方法来减少温室气体排放。  相似文献   
22.
没食子酸—H_2O_2—甲醛—Co(Ⅱ)化学发光体系测定钴   总被引:1,自引:0,他引:1  
本文用没食子酸—H_2O_2—甲醛—CO(Ⅱ)化学发光体系建立了痕量钴的化学发光测定法.方法检出限达0.5ng/ml 钴,线性范围是1×10~(-9)—8×10~(-7)g/ml 钴,测定的相对标准偏差小于1.0%,考察了24种常见离子的干扰情况.方法已用于水样中痕量钴的测定.  相似文献   
23.
The heart is often perceived as a difficult organ to understand by ultrasound during fetal life. This is undoubtedly reflected in the low detection rate of cardiac abnormalities as compared to those of most other organ systems in the fetus. In this article we start by updating classical concepts of cardiac embryology, many of which were previously difficult to understand since they were overly simplistic or purely observational. We then lead on to the structure and growth of the fully formed fetal heart where we review the anatomy and ultrasound appearances in detail and provide comparisons with major abnormalities. We emphasise the fact that a solid understanding of cardiac anatomy can enable those involved in fetal medicine to make full use of the views of the heart that are obtained by ultrasound and which are often only transient. Copyright © 2004 John Wiley & Sons, Ltd.  相似文献   
24.
季戊四醇酯的生物降解评估研究   总被引:2,自引:0,他引:2       下载免费PDF全文
根据用评估润滑油生物降解性的CEC测试方法,对新型冷冻机的润滑油基础油季戊四醇酯的生物降解性以及添加剂对其的影响进行评估,并结合红外光谱讨论季戊四醇酯的生物降解规律。  相似文献   
25.
Hypospadias is one of the most prominent and characteristic midline defects in male infants with the Wolf-Hirschhorn (4p —) syndrome. In this report we present a case in which hypospadias was identified prenatally at 29 weeks' gestation in association with intrauterine growth retardation. Cytogenetic evaluation after birth confirmed a 46, XY, del(4)(p14) karyotype. The prenatal identification of hypospadias in fetuses with intrauterine growth retardation and normal amniotic fluid should suggest a diagnosis of Wolf-Hirschhorn syndrome.  相似文献   
26.
We report the results of carrier and prenatal diagnosis for hypoxanthine guanine phosphoribosyltransferase (HPRT) deficiency, Lesch—Nyhan syndrome, by carrier testing of 83 women and prenatal analysis of 26 pregnancies. Our diagnostic methodologies include mutation detection and linkage analysis for probands and their families and biochemical measurement of HPRT enzyme activity for at-risk pregnancies. Identification of the mutation in the index case of each family permits precise carrier diagnosis using polymerase chain reaction (PCR) amplification of HPRT gene sequences and automated DNA sequencing. We demonstrate 100 per cent sensitivity for the detection of mutations in the HPRT gene of affected males and highly efficient carrier testing of at-risk females. Two other molecular methods proven to have high utility include PCR-based dosage analysis and linkage analysis by PCR amplification of a short tandem repeat (STR) in intron 3 of the HPRT gene. As a result, 45 at-risk women, 56 per cent of those tested, were identified not to be carriers of their family's HPRT gene mutation. Seven of these women were the mothers of affected males and prenatal testing for future pregnancies was recommended because of the possibility of gonadal mosaicism. Thirty-eight of these women were more distant relatives of affected males, thereby eliminating the need for future prenatal procedures. These studies illustrate the utility and precision of molecular methodologies for carrier and prenatal diagnosis of Lesch—Nyhan syndrome. These studies also illustrate that molecular diagnostic studies of affected males and carrier testing prior to pregnancy can clarify genetic risk predictions and eliminate unnecessary prenatal procedures.  相似文献   
27.
The autopsy findings of a fetus with deletion of the long arm of chromosome 8 are described. Many of the features are similar to those of the tricho-rhino-phalangeal syndromes, types I and II, which are associated with deletions on chromosome 8q24. Other findings in this case, such as total absence of the corpus callosum and intestinal malrotation, have not been described in these syndromes. Genes involved in the development of the latter malformations may reside in adjacent regions on the long arm of chromosome 8. An elevated serum level of beta human chorionic gonadotropin (βhCG) was found during pregnancy. This aberration should be included with other chromosomal disorders which may be detected by this test.  相似文献   
28.
X-linked agammaglobulinaemia is an inherited recessive disease in which the primary defect lies in the failure of pre-B cells to develop into mature circulating B cells, due to a defective B-cell cytoplasmic tyrosine kinase (btk). For this study we introduced a new RFLP marker, SP282, which is tightly linked to the XLA locus. In conjunction with the marker DXS178, SP282 was used to identify a carrier female and predict her male offspring to be normal. Subsequently the fetus was shown to have a normal number of circulating B cells, and at 2·5 years of age, the non-affected phenotype of the child was confirmed.  相似文献   
29.
放射源远程自动监控管理体系的构建   总被引:2,自引:0,他引:2       下载免费PDF全文
以苏州的若干家放射源使用单位为例,从点位源的剂量监测、视频监控、红外报警、数据传输等方面出发,围绕提高放射源自动监控这一主题,展开了放射源远程自动监控体系的探索.  相似文献   
30.
尚洪山  杨帆  寇元 《环境科学》2003,24(6):68-73
通过浸渍方法,制备了5%~90%(质量分数)担载量Na2CO3/草粉脱硫剂.实验结果表明,较小的草粉粒度(≤0.28mm)和较低的气体流量(40mL/min)有利于SO2脱除,但是脱硫温度(70℃~300℃)对脱硫效果影响不大.利用XRD,SEM,ATR-IR等分析手段,研究了草粉改性Na2CO3脱硫吸附剂的机理.实验证明:改性Na2CO3吸附剂高效脱硫的机理主要在于吸附剂表面结构的无定形态,因而具有比较大的比表面积(12.14m2/g)和孔体积(0.093cm3/g).  相似文献   
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