全文获取类型
收费全文 | 554篇 |
免费 | 39篇 |
国内免费 | 176篇 |
专业分类
安全科学 | 33篇 |
环保管理 | 12篇 |
综合类 | 346篇 |
基础理论 | 277篇 |
污染及防治 | 60篇 |
评价与监测 | 22篇 |
社会与环境 | 5篇 |
灾害及防治 | 14篇 |
出版年
2024年 | 1篇 |
2023年 | 11篇 |
2022年 | 9篇 |
2021年 | 19篇 |
2020年 | 11篇 |
2019年 | 5篇 |
2018年 | 11篇 |
2017年 | 17篇 |
2016年 | 22篇 |
2015年 | 24篇 |
2014年 | 20篇 |
2013年 | 68篇 |
2012年 | 33篇 |
2011年 | 38篇 |
2010年 | 34篇 |
2009年 | 29篇 |
2008年 | 51篇 |
2007年 | 42篇 |
2006年 | 42篇 |
2005年 | 23篇 |
2004年 | 24篇 |
2003年 | 27篇 |
2002年 | 16篇 |
2001年 | 16篇 |
2000年 | 13篇 |
1999年 | 19篇 |
1998年 | 23篇 |
1997年 | 18篇 |
1996年 | 18篇 |
1995年 | 18篇 |
1994年 | 18篇 |
1993年 | 10篇 |
1992年 | 7篇 |
1991年 | 6篇 |
1990年 | 4篇 |
1989年 | 6篇 |
1988年 | 9篇 |
1987年 | 2篇 |
1986年 | 3篇 |
1984年 | 1篇 |
1983年 | 1篇 |
排序方式: 共有769条查询结果,搜索用时 406 毫秒
171.
用SD大鼠原代肝细胞作程序外DNA合成(UDS)试验,检测黄浦江上游水源保护区9家工厂的工业废水,结果表明,在不同时间采集的9家工厂的两批工业废水UDS试验均呈阳性,并且呈剂量—反应关系。这说明9家工厂的工业废水有潜在的致突变作用和致癌作用,对这些工业废水的排放应加以控制。 相似文献
172.
从石油污染土壤中分离纯化到 3株能以菲为唯一碳源和能源生长的革兰氏阴性杆菌、好氧、不形成芽孢、端生或侧生单根鞭毛 ,分别命名为菌株ZX4、ZX6和EVA17.据部分片段长度的 16SrDNA序列比对分析和生理生化试验结果 ,确认此 3株菌均为鞘氨醇单胞菌属 (Sphingomonas)细菌 ,菌株ZX4为少动鞘氨醇单胞菌 (S .paucimobilis) ,菌株ZX6为溶芳烃鞘氨醇单胞菌 (S .aromaticivorans) ,菌株EVA17尚不能确定 .分析了各菌株在系统发育中的分类地位 .菌株ZX4在 14d内对含量为 10 0 0mg·L-1的菲降解率可达 98 74%.不同底物实验结果表明 ,菌株EVA17可能同时拥有两条菲降解途径 . 相似文献
173.
Irma Järvelä MD Juhani Rapola Leena Peltonen Lea Puhakka Jouni Vesa Pirkko Ämmälä Riitta Salonen Markku Ryynänen Pertti Haring Aki Mustonen Pirkko Santavuori 《黑龙江环境通报》1991,11(5):323-328
Eleven fetuses at risk for the infantile form of neuronal ceroid lipofuscinosis (INCL, CLN1) were studied using DNA markers and the results were compared with the results of electron microscopy (EM) of chorionic villus specimens from pregnancies in the first or early second trimester of pregnancy. In four cases, the prenatal diagnosis was made independently with both methods, and in seven cases, the EM diagnosis was confirmed postnatally or from autopsy material using RFLP analysis. The two methods gave concordant results in all cases. The DNA analysis based on RFLP haplotypes also for the first time facilitates reliable carrier diagnostics. RFLP analysis based on polymorphic markers closely linked to the INCL locus is now available for prenatal diagnosis of this fatal brain disease, whose biochemical background is totally unknown and for which no treatment is available. 相似文献
174.
寡核苷酸探针LZF-I进行两栖类DNA指纹分析的初步研究 总被引:2,自引:0,他引:2
利用寡核苷酸探针LZF-I对两栖类的3属8种28只个体的冷冻和甲醛固定的肝组织作了检测.所获DNA指纹图在个体、种和属间具有特异性.表明该探针进行DNA指纹检测可为两栖动物种、属分类提供依据. 相似文献
175.
佛坪三官庙地区大熊猫种群数量的DNA指纹分析 总被引:5,自引:0,他引:5
应用同位素标记大熊猫基因指纹探针F2ZGP96060801,以秦岭南坡中段佛坪国家级大熊猫自然保护区三官庙范围内采集的大熊猫粪便样品作材料,进行了DNA指纹检测.(1)在相同或不同时间、领域采得的粪便样品,显现出相同或不同的DNA指纹图谱,达到个体认定的目的,进一步表明了大熊猫的尽量新鲜的粪便,可以作为DNA指纹分析材料,进行野生种群数量调查.(2)根据检测21个粪便样品的结果,无误地认定了三官庙地区有13只大熊猫个体.其中有3个家系.(3)大熊猫粪便样品的DNA指纹图,通过微机识别的个体数,准确可靠,能获得大熊猫在野外的真实个体数量. 相似文献
176.
Rocky Mountain bighorn rams use three distinct tactics in competition for mates. Two tactics (tending and blocking) feature
defense and cooperative mating over a relatively prolonged consort period (up to 3 days). In the coursing tactic, subordinate
rams fight dominants for temporary copulatory access (lasting seconds) to defended ewes. By combining population-wide genetic
(microsatellite) exclusion of paternity, behavioral data and a model of bighorn reproductive competition, we estimated that
coursing rams fathered 44% of 142 lambs assigned paternity in two natural populations. In one population, the probability
of successful defense against coursing was lowest among rams that had many female consorts and held highest dominance rank.
Even so, per capita annual male reproductive success was positively associated with social rank in both herds when measured
in terms of fall conceptions. The proportion of coursing versus defending ram matings in each population (0.36 and 0.39) was
similar to the corresponding fraction of lambs (0.43 and 0.47) fathered by coursing rams, suggesting that sperm competition
approximated a fair lottery. Male traits important in gaining social status and obtaining cooperative consorts with ewes were
different and potentially in conflict with those needed to defend against (and practise) coursing. Although the concussive
weapons (horns) of rams are less dangerous than, for example, the piercing weapons of other bovids, injury from falls and
horn blows during coursing brawls may cause death, handicap future mating competition or increase the risk of predation. Coursing
is a rare example of an unconventional alternative mating tactic that is high-gain and high-risk.
Received: 17 April 1996 / Accepted after revision: 15 March 1997 相似文献
177.
Differential use of stored sperm during oviposition in the damselfly Calopteryx splendens xanthostoma (Charpentier) 总被引:2,自引:0,他引:2
Female Calopteryx splendens xanthostoma (Charpentier) (Odonata), have two discrete sperm storage organs, the bursa copulatrix and the paired spermathecae. We used
the Random Amplified Polymorphic DNA(RAPD) profiling technique to determine from which sperm storage organ spermatozoa were used to fertilise eggs during behaviourally
distinct oviposition bouts. During oviposition bouts following remating sperm from the bursa copulatrix are largely used to
fertilise eggs, but when females avoid remating before an oviposition bout the sperm used to fertilise eggs are derived mainly
from the paired spermathecae. Our observations suggest that female C. s. xanthostoma can avoid male paternity assurance mechanisms by a combination of behavioural and anatomical adaptation: the reason(s) they
do so is unclear.
Received: 28 November 1995/Accepted after revision: 5 August 1996 相似文献
178.
179.
本文对化学品登记所要求的部分健康效应数据——皮肤致敏、重复经口染毒、致变做了解释.涉及到的测试参数包括:皮肤致敏、重复(14/28天)经口啮动物毒性、基因突变、染色体畸变和DMA效应. 相似文献
180.
一种经济、简单的微生物基因组DNA的提取方法 总被引:6,自引:0,他引:6
获得一定浓度和纯度的DNA是进行分子生物学研究的基础。破解细胞壁与细胞膜是获得基因组DNA的前提,而蛋白质和核酸物质的分离是获得高质量DNA产物的关键。目前,主要采用的破壁方法有:冷冻研磨法、溶菌酶法、EDTA测等,这些方法一般采用复杂的裂解液体系,并借助蛋白酶K和RNA酶的帮助来获得高质量的抽提产物。由于细胞裂解体系不仅配制十分麻烦,而日部分药品有毒操作危险性大,此外部分药品及相关酶试剂价格昂贵。本文充分利用DNA在不同温度下自身可变性与复性的特性和在高盐与高温条件下蛋白质能够变性并沉淀。以无菌的SDS(c/c=20%)和NaCl(c/c=8%)的混合液作裂解体系,在沸水浴中破壁膜并使得部分的蛋白质变性和DNA变性并得到初步分离;随后在60℃和72℃水浴中使变性的DNA复性和重新凝聚,同时让RNA、蛋白质和细胞壁碎片等杂质降解或沉淀,从而获得高质量的DNA产物。 相似文献