全文获取类型
收费全文 | 20929篇 |
免费 | 253篇 |
国内免费 | 126篇 |
专业分类
安全科学 | 552篇 |
废物处理 | 897篇 |
环保管理 | 2837篇 |
综合类 | 3435篇 |
基础理论 | 5908篇 |
环境理论 | 12篇 |
污染及防治 | 5351篇 |
评价与监测 | 1304篇 |
社会与环境 | 874篇 |
灾害及防治 | 138篇 |
出版年
2021年 | 141篇 |
2019年 | 136篇 |
2018年 | 254篇 |
2017年 | 263篇 |
2016年 | 424篇 |
2015年 | 323篇 |
2014年 | 480篇 |
2013年 | 1622篇 |
2012年 | 603篇 |
2011年 | 838篇 |
2010年 | 678篇 |
2009年 | 686篇 |
2008年 | 847篇 |
2007年 | 880篇 |
2006年 | 785篇 |
2005年 | 672篇 |
2004年 | 654篇 |
2003年 | 633篇 |
2002年 | 616篇 |
2001年 | 765篇 |
2000年 | 576篇 |
1999年 | 327篇 |
1998年 | 261篇 |
1997年 | 278篇 |
1996年 | 283篇 |
1995年 | 332篇 |
1994年 | 304篇 |
1993年 | 285篇 |
1992年 | 278篇 |
1991年 | 278篇 |
1990年 | 294篇 |
1989年 | 277篇 |
1988年 | 249篇 |
1987年 | 240篇 |
1986年 | 223篇 |
1985年 | 201篇 |
1984年 | 255篇 |
1983年 | 210篇 |
1982年 | 272篇 |
1981年 | 225篇 |
1980年 | 189篇 |
1979年 | 201篇 |
1978年 | 184篇 |
1977年 | 155篇 |
1976年 | 138篇 |
1975年 | 143篇 |
1974年 | 159篇 |
1973年 | 162篇 |
1972年 | 150篇 |
1971年 | 146篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
611.
A protocol for easy storage and later expansion of lymphocyte populations is given. Compared with methods using transformed cell lines, the method has a number of advantages for repeated production of cells for the isolation of DNA in amounts sufficient for use in diagnostic DNA technology. 相似文献
612.
Hurler's disease was excluded in a fetus at 23 weeks' gestation by demonstrating normal iduronidase activity in fetal leucocytes following failure of amniotic cell culture after amnic-centesis at 16 and 19 weeks' gestation. The diagnosis was confirmed in the neonate. 相似文献
613.
614.
615.
The sympatric neotropical termites Nasutitermes corniger and Nasutitermes ephratae are clearly distinguishable based on morphology, nest architecture, defensive secretion composition, and molecular markers.
However, given the extensive ecological, geographical, and behavioral overlap of these closely related species, the potential
for interbreeding may exist. To explore this possibility, heterospecific pairs were formed experimentally to examine courtship
and colony-establishment behaviors, and reproductive potential. Courtship and nest construction behavior occurred in heterospecific
pairs in a similar manner to that of conspecific pairs. Survival of pairs depended upon the species of the female partner.
N. ephratae females paired with N. corniger males produced as many offspring as conspecific pairs. N. corniger females mated to N. ephratae males, however, produced significantly fewer offspring at 60 days post-establishment than the reciprocal cross or conspecific
N. ephratae or N. corniger pairs. This was also the only pairing in which any aggression was observed. Heterospecific pairs and groups formed in mate
choice mesocosms, suggesting that species recognition between these two termites is not an important aspect of mate choice.
Overall, species mismatch tolerance and hybrid offspring viability are high. The present data, together with previous evidence
from defensive secretions and isozyme analysis, suggest that hybridization may periodically occur in nature, and that reproductive
barriers between these two species may be incomplete. Hybridization could provide a rare but important source of genetic diversity
and may ensure mating opportunities for the more abundant sex of alates in each species. 相似文献
616.
Brooke E. Willborg Eniola R. Ibirogba Ayssa Teles Abrao Trad Lourenço Sbragia Dean Potter Rodrigo Ruano 《黑龙江环境通报》2021,41(1):159-176
We conducted a comprehensive evidence-based review on the epidemiology and current standard of care of gastroschisis management as well as the pathophysiology, rationale and feasibility of fetal therapy as a viable alternative. Gastroschisis is a periumbilical abdominal wall defect characterized by abdominal viscera herniation in utero. It affects 4 in 10 000 live births, but the prevalence has steadily increased in recent years. Gastroschisis is typically diagnosed on routine second-trimester ultrasound. The overall prognosis is favorable, but complex gastroschisis, which accounts for about 10% to 15% of cases, is associated with a higher mortality, significant disease burden and higher healthcare costs due to long- and short-term complications. The current standard of care has yet to be established but generally involves continued fetal surveillance and multidisciplinary perinatal care. Postnatal surgical repair is achieved with primary closure, staged silo closure or sutureless repair. Experimental animal studies have demonstrated the feasibility of in utero closure, antiinflammatory therapy and prenatal regenerative therapy. However, reports of early preterm delivery and amnioinfusion trials have failed to show any benefit in humans. Further experimental studies and human trials are necessary to demonstrate the potential benefit of fetal therapy in gastroschisis. 相似文献
617.
618.
N. H. Ravindranath Rajiv K. Chaturvedi N. V. Joshi R. Sukumar Jayant Sathaye 《Mitigation and Adaptation Strategies for Global Change》2011,16(2):211-227
Climate change is projected to impact forest ecosystems, including biodiversity and Net Primary Productivity (NPP). National
level carbon forest sector mitigation potential estimates are available for India; however impacts of projected climate change
are not included in the mitigation potential estimates. Change in NPP (in gC/m2/yr) is taken to represent the impacts of climate change. Long term impacts of climate change (2085) on the NPP of Indian
forests are available; however no such regional estimates are available for short and medium terms. The present study based
on GCM climatology scenarios projects the short, medium and long term impacts of climate change on forest ecosystems especially
on NPP using BIOME4 vegetation model. We estimate that under A2 scenario by the year 2030 the NPP changes by (−5) to 40% across
different agro-ecological zones (AEZ). By 2050 it increases by 15% to 59% and by 2070 it increases by 34 to 84%. However,
under B2 scenario it increases only by 3 to 25%, 3.5 to 34% and (−2.5) to 38% respectively, in the same time periods. The
cumulative mitigation potential is estimated to increase by up to 21% (by nearly 1 GtC) under A2 scenario between the years
2008 and 2108, whereas, under B2 the mitigation potential increases only by 14% (646 MtC). However, cumulative mitigation
potential estimates obtained from IBIS—a dynamic global vegetation model suggest much smaller gains, where mitigation potential
increases by only 6% and 5% during the period 2008 to 2108. 相似文献
619.
620.