全文获取类型
收费全文 | 23493篇 |
免费 | 100篇 |
国内免费 | 155篇 |
专业分类
安全科学 | 346篇 |
废物处理 | 1320篇 |
环保管理 | 2713篇 |
综合类 | 4118篇 |
基础理论 | 6311篇 |
环境理论 | 6篇 |
污染及防治 | 5211篇 |
评价与监测 | 2045篇 |
社会与环境 | 1608篇 |
灾害及防治 | 70篇 |
出版年
2022年 | 126篇 |
2021年 | 106篇 |
2019年 | 101篇 |
2018年 | 1594篇 |
2017年 | 1508篇 |
2016年 | 1447篇 |
2015年 | 341篇 |
2014年 | 408篇 |
2013年 | 1026篇 |
2012年 | 876篇 |
2011年 | 1857篇 |
2010年 | 1123篇 |
2009年 | 1087篇 |
2008年 | 1398篇 |
2007年 | 1752篇 |
2006年 | 537篇 |
2005年 | 510篇 |
2004年 | 481篇 |
2003年 | 513篇 |
2002年 | 525篇 |
2001年 | 609篇 |
2000年 | 382篇 |
1999年 | 262篇 |
1998年 | 155篇 |
1997年 | 164篇 |
1996年 | 171篇 |
1995年 | 188篇 |
1994年 | 179篇 |
1993年 | 131篇 |
1992年 | 164篇 |
1991年 | 172篇 |
1990年 | 168篇 |
1989年 | 141篇 |
1988年 | 156篇 |
1987年 | 96篇 |
1986年 | 128篇 |
1985年 | 127篇 |
1984年 | 133篇 |
1983年 | 122篇 |
1982年 | 120篇 |
1981年 | 120篇 |
1980年 | 87篇 |
1979年 | 99篇 |
1978年 | 101篇 |
1976年 | 92篇 |
1974年 | 104篇 |
1972年 | 87篇 |
1971年 | 85篇 |
1967年 | 100篇 |
1964年 | 92篇 |
排序方式: 共有10000条查询结果,搜索用时 78 毫秒
321.
322.
A population of 1639 patients were seen for chorionic villus sampling (CVS). Embryonic death was identified at ultrasound in 5.3 per cent of patients. The number of patients undergoing CVS was 1551, with 1416 transcervical procedures and 135 transabdominal procedures. The most common indication for CVS was advanced maternal age. Spontaneous pregnancy losses identified by increased risk of pregnancy loss with increasing aspiration attempts. The total fetal loss for this population was 5.4 per cent with the pregnancy loss estimated due to procedure being 1.2 per cent. Analysis of placentae from patients having CVS and amniocen-tesis showed no differences. Microbiological assessment prior to CVS was similar to previous publications. 相似文献
323.
324.
325.
326.
Umberto Nicolini Nicholas M. Fisk David G. Talbert Charles H. Rodeck Neil K. Kochenour Pantaleo Greco Corinne Hubinont Joaquin Santolaya 《黑龙江环境通报》1989,9(4):243-254
A technique is described for measuring pressure within the amniotic cavity and within fetal vessels and/or body compartments. Two saline-filled catheters were connected at one end to needles inserted during indicated invasive procedures and at the other to silicon strain gauge transducers. In 36 pregnancies with normal liquor volume, stable intra-amniotic pressure (IAP, range 1–14 mmHg) increased with gestation (r=0·48, p<0·01). In pregnancies complicated by severe oligohydramnios, IAP was ≤ 1 mm Hg and rose to normal levels with saline amnioinfusion. Raised IAP (range 17–26 mm Hg), found in pregnancies with gross polyhydramnios, fell with drainage of amniotic fluid. Subtraction manometry was used to determine supra-amniotic pressure within the intervillus space, umbilical vein, umbilical artery, abdominal and thoracic cavities, and the urinary tract in normal and/or pathological fetuses. Low intravesical and intrapelvicalyceal pressures (median 6·5, range 2–10 mmHg) were noted in fetuses with obstructive uropathies. Intrauterine subtraction manometry appears to be a useful tool in the understanding of fetal pathophysiology and may be of clinical benefit in the therapeutic drainage and infusion of amniotic fluid and in the assessment of certain fetal disease states. 相似文献
327.
We are very grateful to A. Gessner for his great help in the construction of the apparatus and A. Meyer for performance of some pressure bomb experiments. This work was supported by grants of the Deutsche Forschungsgemeinschaft (Forschergruppe Ökophysiologie) to U.Z. and O.L.L. 相似文献
328.
329.
330.