全文获取类型
收费全文 | 28718篇 |
免费 | 278篇 |
国内免费 | 237篇 |
专业分类
安全科学 | 663篇 |
废物处理 | 1170篇 |
环保管理 | 3440篇 |
综合类 | 5690篇 |
基础理论 | 7228篇 |
环境理论 | 10篇 |
污染及防治 | 7225篇 |
评价与监测 | 1891篇 |
社会与环境 | 1783篇 |
灾害及防治 | 133篇 |
出版年
2022年 | 218篇 |
2021年 | 208篇 |
2019年 | 197篇 |
2018年 | 365篇 |
2017年 | 393篇 |
2016年 | 592篇 |
2015年 | 467篇 |
2014年 | 717篇 |
2013年 | 2125篇 |
2012年 | 828篇 |
2011年 | 1177篇 |
2010年 | 986篇 |
2009年 | 1023篇 |
2008年 | 1185篇 |
2007年 | 1249篇 |
2006年 | 1090篇 |
2005年 | 922篇 |
2004年 | 932篇 |
2003年 | 927篇 |
2002年 | 876篇 |
2001年 | 1122篇 |
2000年 | 766篇 |
1999年 | 498篇 |
1998年 | 325篇 |
1997年 | 372篇 |
1996年 | 384篇 |
1995年 | 413篇 |
1994年 | 416篇 |
1993年 | 361篇 |
1992年 | 366篇 |
1991年 | 359篇 |
1990年 | 359篇 |
1989年 | 335篇 |
1988年 | 293篇 |
1987年 | 286篇 |
1986年 | 276篇 |
1985年 | 280篇 |
1984年 | 295篇 |
1983年 | 286篇 |
1982年 | 276篇 |
1981年 | 247篇 |
1980年 | 230篇 |
1979年 | 231篇 |
1978年 | 207篇 |
1977年 | 212篇 |
1976年 | 165篇 |
1975年 | 175篇 |
1974年 | 193篇 |
1973年 | 175篇 |
1972年 | 164篇 |
排序方式: 共有10000条查询结果,搜索用时 348 毫秒
431.
C. A. Dell'Agnola V. Tomaselli E. Teruzzi B. Tadini A. G. Coran Surgeon-in-Chief 《黑龙江环境通报》1993,13(7):629-632
The impact of prenatal sonographic diagnosis of oesophageal and gastrointestinal obstructions has been analysed over a 10-year period. Three groups of patients were evaluated. The first group consisted of 46 newborns with abnormal prenatal sonogratns, 41 of which were confirmed to have intestinal obstruction postnatally. The second group consisted of 17 neonates with normal prenatal sonograms who had intestinal obstruction postnatally. The third group included 56 newborns who did not undergo a prenatal sonogram but who had intestinal obstruction confirmed at surgery. Polyhydramnios without the appearance of a stomach on ultrasound was diagnostic of pure oesophageal atresia. Polyhydramnios with intestinal dilation was diagnostic of intestinal obstruction. Although surgery was performed earlier in the infants diagnosed prenatally with ultrasound, mortality was no less than in the group that did not undergo a prenatal sonogram, probably because of the high incidence of associated anomalies. 相似文献
432.
While true mosaicism occurs in only 0–25 per cent of genetic amniocenteses, nearly 2–5 per cent of amniotic fluid cell cultures contain a second cell line. In the common practice of prenatal diagnosis, an aberrant cell line confined to a single colony is usually disregarded. We present a case of mosaic trisomy 14 which was not detected on initial chromosome analysis. At birth, multiple malformations were apparent. Newborn cytogenetic studies revealed mosaicism [46,XX/46,XX,-14,+i(14q)] with an isochromosome 14 in 37 per cent of lymphocytes. Additional cells from the initial amniotic fluid culture were analysed post-delivery and the isochromosome 14 identified in only one of 12 total colonies. This case illustrates two important lessons in prenatal diagnosis. First, amniotic fluid cell cultures may not accurately reflect the relative distribution of the normal and abnormal cell lines within a mosaic fetus. Second, while it is generally reasonable to disregard mosaicism confined to a single colony, this policy will, on rare occasion, result in diagnostic error. This should be taken into consideration, particularly when dealing with autosomal trisomies potentially compatible with livebirth. 相似文献
433.
434.
435.
436.
437.
G. Piekarski 《Die Naturwissenschaften》1980,67(1):29-34
The increasing interest in the parasites of man in the Federal Republic of Germany is connected with the unbounded keenness of German people to travel. They favor southern regions with warm climates which are usually infested with parasites. Thus the general practitioner is nowadays confronted in his daily routine with “imported” pathogenic organisms and diseases as yet unknown to him or with which he need not have reckoned in the past. Furthermore, new information now exists on the development of well-known parasites of our regions, which can be pathogenic to man. Fortunately, new reliable drugs have come on the market, rendering some parasitic diseases harmless. 相似文献
438.
In this paper we deal with the problem of identifying environmental principles for the design and operation of supply chains. The operations that are included in supply chains are briefly described along with the approaches that are applied in order to improve their environmental performance. A background of environmental principles for achieving eco-efficiency and building of environmentally friendly organizational systems is presented and emphasis is put on the application of such principles “from cradle to grave”. Then, environmental principles applicable to particular objects of logistics networks planning are identified and commented upon. In addition, selective case studies from the literature, which show the applicability of the formulated principles and their relevance to practice, are discussed. The paper concludes with some remarks regarding the benefits for companies and societies, in general, that occur as a result of the application of the formulated principles. 相似文献
439.
Circulating placental [human chorionic gonadotrophin (hCG), Schwangerschafts protein 1 (SP1), pregnancy-associated plasma protein A (PAPP-A), decidual (pregnancy protein) 12 (PP12), and fetal alphafetoprotein (AFP)] proteins were measured immediately before and within 1 h in 18 women undergoing diagnostic chorionic villus sampling (CVS) in the first trimester. An elevation of serum AFP levels was consistently seen, while fluctuations in excess of 10 per cent of the pre-CVS levels of SP1 and PP12 were seen in the majority of patients. Fluctuations in hCG and PAPP-A were consistently less than 10 per cent of pre-CVS values. Post-CVS changes in levels were not apparently associated with any feature of the technique, the pregnancy, or its outcome (one missed abortion). As feto-maternal haemorrhage is a common event, anti-D should be offered to rhesus-negative women undergoing CVS. In the prediction of subsequent miscarriage, only hCG and PAPP-A measurements should be considered. 相似文献
440.