全文获取类型
收费全文 | 16138篇 |
免费 | 110篇 |
国内免费 | 69篇 |
专业分类
安全科学 | 333篇 |
废物处理 | 638篇 |
环保管理 | 1925篇 |
综合类 | 3740篇 |
基础理论 | 3641篇 |
环境理论 | 6篇 |
污染及防治 | 3961篇 |
评价与监测 | 1014篇 |
社会与环境 | 1013篇 |
灾害及防治 | 46篇 |
出版年
2022年 | 111篇 |
2021年 | 131篇 |
2019年 | 126篇 |
2018年 | 200篇 |
2017年 | 192篇 |
2016年 | 310篇 |
2015年 | 243篇 |
2014年 | 361篇 |
2013年 | 1090篇 |
2012年 | 408篇 |
2011年 | 615篇 |
2010年 | 473篇 |
2009年 | 554篇 |
2008年 | 636篇 |
2007年 | 673篇 |
2006年 | 603篇 |
2005年 | 506篇 |
2004年 | 530篇 |
2003年 | 518篇 |
2002年 | 488篇 |
2001年 | 622篇 |
2000年 | 395篇 |
1999年 | 295篇 |
1998年 | 186篇 |
1997年 | 205篇 |
1996年 | 224篇 |
1995年 | 233篇 |
1994年 | 233篇 |
1993年 | 219篇 |
1992年 | 198篇 |
1991年 | 207篇 |
1990年 | 198篇 |
1989年 | 169篇 |
1988年 | 168篇 |
1987年 | 154篇 |
1986年 | 153篇 |
1985年 | 148篇 |
1984年 | 169篇 |
1983年 | 167篇 |
1982年 | 173篇 |
1981年 | 144篇 |
1980年 | 132篇 |
1979年 | 123篇 |
1978年 | 134篇 |
1977年 | 115篇 |
1976年 | 103篇 |
1975年 | 107篇 |
1974年 | 118篇 |
1971年 | 98篇 |
1967年 | 101篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
861.
862.
863.
864.
Iniencephaly is an uncommon, but not rare, lesion involving a fusion between the posterior occipital bone and the cervical spine. Many cases are associated with other cranio-cervical abnormalities and anencephaly, and most are associated with other structural abnormalities. The prognosis is thought to be dismal. We describe a male infant, one of twins, who was diagnosed prenatally as having iniencephaly. The child was born without complication and has grown and thrived. This is the fourth patient with long-term survival with iniencephaly. We recommend that non-directive counselling be applied when presenting the findings of iniencephaly to parents. 相似文献
865.
After partial hepatectomy the low proliferation rate of hepatocytes increases dramatically. This is based on a feed-back system whose central link is a liver cell proliferation hormon, the so-called hepatopoietin. The hormon originates from the Peyer's patches: after their resection, the liver cell proliferation after partial hepatectomy decreases by about 80%. Hepatopoietin effects organ specific but species nonspecific. 相似文献
866.
867.
J. C. M. Pires A. L. Gonçalves F. G. Martins M. C. M. Alvim-Ferraz M. Simões 《Mitigation and Adaptation Strategies for Global Change》2014,19(7):1109-1117
Carbon dioxide (CO2) is one of the primary greenhouse gases that contribute to climate change. Consequently, emission reduction technologies will be needed to reduce CO2 atmospheric concentration. Microalgae may have an important role in this context. They are photosynthetic microorganisms that are able to fix atmospheric CO2 using solar energy with efficiency ten times higher than terrestrial plants. The objectives of this study were: (i) to analyse the effect of light supply on the growth of Chlorella vulgaris and Pseudokirchneriella subcapitata; (ii) to assess the atmospheric CO2 capture by these microalgae; and (iii) to determine the parameters of the Monod model that describe the influence of irradiance on the growth of the selected microalgae. Both microalgae presented higher growth rates with high irradiance values and discontinuous light supply. The continuous supply of light at the highest irradiance value was not beneficial for C. vulgaris due to photooxidation. Additionally, C. vulgaris achieved the highest CO2 fixation rate with the value of 0.305 g-CO2 L?1 d?1. The parameters of the Monod model demonstrated that C. vulgaris can achieve higher specific growth rates (and higher CO2 fixation rates) if cultivated under higher irradiances than the studied values. The presented results showed that microalgal culture is a promising strategy for CO2 capture from atmosphere. 相似文献
868.
The Science of Nature - 相似文献
869.
870.
Nusholtz GS Famili F Di Domenico L Shi Y Aoun ZB Hongsakaphadana Y 《Traffic injury prevention》2003,4(2):128-135
An investigation was conducted to estimate the effectiveness of air bags as a function of velocity. The study consisted of three parts: a theoretical idealization, an analysis of National Automotive Sampling System/Crashworthiness Data System (NASS/CDS), and a reanalysis of previously published Fatality Analysis Reporting System (FARS) data. The theoretical analysis looked at idealized risk curves as a function of velocity; assuming that the air bag offers a benefit for both belted and unbelted occupants. Analysis of the NASS/CDS data looked at the effectiveness of air bags as a function of velocity for Maximum Abbreviated Injury Scale (MAIS) 3+ injuries. The reanalysis of the previously published FARS data looked at the effectiveness of the air bag as a function of velocity for fatalities. The theoretical analysis indicates that the air bag effectiveness should be greatest at the low velocities. The field data analysis of both NASS/CDS and FARS were consistent with the theoretical analysis, indicating that air bags are most effective at the lower velocities, below 40 kph (25 mph), for both belted and unbelted occupants. Although it was not possible to estimate a different effect for belted and unbelted for fatalities using FARS, it was possible for MAIS 3+ using NASS/CDS. For unbelted occupants the effectiveness goes to zero or becomes negative above 40 kph (25 mph) for MAIS 3+, and for belted occupants the effectiveness stays positive but with significantly lower magnitude for speeds above 40 kph (25 mph). 相似文献