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991.
Summary Larvae of Panolis flammea and Bupalus piniarius were reared in the laboratory on needles of Scots pine affected by industrial air pollutants in Finland. Needles were collected at different distances from a distinctive source of emission along two 9-km-long transects, and from independent control plots. The elemental composition of the needles used as larval food was analysed. Pupal weight, length and width were negatively correlated wiht the distance from the source of emission. The elemental composition of the pine needles explained 24–53% of the variation in pupal weight. Most of the explained variation was assoicated with the concentration of heavy meals in the pine needles. 相似文献
992.
Studies with sterile root materials showed that the optimum pH values of phosphatase activity in three varieties of each of
corn (Zea mays L.) and soybean (Glycine max. L.) were 4 and 5, respectively. The activity on either side of the optimum pH fell sharply, and there was no activity at
pH 9. Thus, these roots contain acid but no alkaline phosphatase activity. Acid phosphatase activity was not uniformly distributed
in roots and root hairs. Studies with 20 metals showed that their effectiveness in inhibiting acid phosphatase activity of
roots varied with the type of plant used. When the metals were compared at 250 μM (1.25 μmole. 5 mg−1 of homogenized roots), the inhibition of acid phosphatase of corn and soybean roots showed that Ag(I), Fe(III), Se(IV), V(IV),
As(V) and Mo(VI) were the most effective inhibitors of this enzyme in corn roots, with percentage inhibition ≥30%. In addition
to these metals, Sn(II), Hg(II), and W(VI) inhibited acid phosphatase in soybean roots by >30%. Other metals and one non-metallic
element that inhibited acid phosphatase activity in corn and soybean roots were: Cu(I), Cu(II), Cd(II), Ni(II), Fe(II), Pb(II),
Ba(II), Co(II), Mn(II), Zn(II), B(III), As(III), Cr(III), and Al(III); their degrees of effectiveness varied with type of
roots used. Generally, the inhibitory effect of the metals was much less when their concentration was decreased by 10-fold.
In addition to the effect of these elements, phosphate ion inhibited acid phosphatase activity of corn and soybean roots.
Related anions such as NO
2
−
, NO
3
−
, Cl−, and SO
4
2−
were not inhibitory. 相似文献
993.
Metal (Cu, Ni, Zn, Fe, Mn and Al) budgets were measured for 5 lakes and their catchments near Sudbury, Ontario, an area severely affected by the emission and deposition of strong acids (H2SO4/SO2) and metals. Three of the lakes were circum-neutral (pH 6.3–7.1) during the study period, while one lake had a pH of 4.8 and a fifth had very low pH ( 4.4).The lakes' catchments were all sources of Al, Mn and Ni, but were sinks for Cu and Zn. The Fe results were inconsistent; two lakes' catchments were sources while three were sinks.The acidic lakes were conservative (i.e. net retention of zero) with respect to Cu and Ni, while the circum-neutral lakes were effective sinks for these 2 metals. All of the lakes were sinks for Zn and Al, but the acidic lakes were less effective. All lakes were also Fe sinks. While there was no pattern relative to the lakes' pH's, there was a trend towards increasing Fe retention with increasing water replenishment time. The most acidic lake was actually a source of Mn, while the others were sinks. 相似文献
994.
Sediment from lakes on abandoned coal mines in the Midwestern U.S.A. was examined to determine the factors controlling chemical composition and the role the sediment plays in lake neutralization. Sediment concentrations of many cations, (especially heavy metals) are strongly correlated with sediment sulfide concentration, but poorly correlated with the pH of the overlying water. Leaching the sediment of one lake with 1 N ammonium acetate, 0.1 N HCl, and 6 N HCl revealed that cations were mostly bound in weak acid-leachable and strong acid-leachable forms. The weak acid-leachable form is likely to be metal sulfides and calcium carbonate. The sulfide-poor sediments of extremely acid lakes contained few weak acid-leachable cations. Raw mine-spoil contained large amounts of easily leached cations. There is little relationship between changes in sediment chemistry over time determined from cores of lake sediment and past lake pH. Rates of sulfide deposition were examined in sediment cores because sulfate reduction and deposition has been suggested as a major source of alkalinity in lakes influenced by acid precipitation. Although the rate of sulfate deposition in surface mine lakes is high, it alone seems to be insufficient to cause neutralization. 相似文献
995.
The relation between conditions leading to precipitation and/or activation of Ru-P2 carboxylase have been explored in order to test the hypothesis that conformational changes leading to precipitation might be identical to those which are presumed to lead to enzyme activation. From the results of kinetic and solubility studies, we conclude that this hypothesis is not valid, since changes in solubility of Ru-P2 carboxylase occur ten times as fast as changes in enzyme kinetics.Abbreviations Ru-P2
ribulose 1,5-bisphosphate
- PVP
polyvinylpyrrolidone
- DTE
dithioerythritol
- Bicine
N,N-bishydroxy-2-ethylglycine 相似文献
996.
Vanadium is important as an indicator of oil pollution since oil is one of the main contributors of vanadium to the environment and because most crude oils contain relatively high concentrations of vanadium (30.6 ± 14.3 mg kg–1 were measured in nine different Kuwait crudes). If oil has settled to the bottom and biodegradation has taken place, it is obvious that enrichment of vanadium in the sediment may be observed.More than 200 sampling sites were selected in the coastal zone of Kuwait and sediment samples were analyzed for grain size distribution, CaC03 content, heavy metals and TOC. The analytical results were normalized by taking into account the natural background levels of vanadium in different sediment fractions.After evaluation of the results, vanadium enrichments of as much as 10 to 77 mg kg–1 were found at 15 sampling locations and of 1 to 10 mg kg–1 at many others. The areas of vanadium enrichment in the sediments were located 3–5 km from the shoreline in the areas of wastewater discharges, near oil loading piers and in the shipping channels. There was no correlation between vanadium and TOC indicating that biodegradation of oils had taken place. However, high TOC values in the sediments were determined in the near shore sediments around the outlets. 相似文献
997.
The acute toxicity of Cu, Cd and Cr to the marine copepod Tisbe holothuriae, Humes, was estimated by static bioassays and the LC
inf50
su48h
(in mg/l) was calculated. Copper proved to be the most toxic (LC
inf50
su48h
= 0,08 ± 0,01 mg/l) and chromium the least toxic (LC
inf50
su48h
= 8,14 ± 0,05 mg/l), while cadmium showed an intermediate toxicity (LC
inf50
su48h
= 0,97 ± 0,04 mg/l).In mixtures of the two metals an obvious synergism of the effects was observed in all cases. In all three combinations with two metals (Cu + Cd, Cu + Cr, and Cd + Cr) the mortality was higher than that expected on a purely additive basis. The mixture of the three metals presented a higher toxicity than that of the individual metals acting separately, but lower than that of all two metals mixture. 相似文献
998.
G. Nakos 《Plant and Soil》1982,66(2):271-277
Summary The Thriasian Plain near Athens in Greece is a site of concentrated industrial development. Total concentrations of Pb, Cd and extractable SO4
2– in surface soil samples collected from this area, were found to be, respectively, 2–7, 6–34 and 2–20 times higher than those in similar soil samples from parts of the country remote from industrial activity.Total concentrations of Pb, Cd, Zn, Cr and S in samples of olive leaves from the same area were found to be, respectively, 4–40, 3–10, 3–9, 2–6 and 17–21 times higher than those found in samples of olive leaves from rural sites. Leaves of cabbages growing in the area contained between 0.82 and 40 g/g (wet weight) of Pb.Addition of Cd, Ni and Cu to a calcareous potted soil at concentrations of 100, 200 and 200 ppm increased the concentrations of the metals in the needles of Aleppo pine (Pinus halepensis) seedlings to 4.5, 3.5 and 10 ppm, respectively, after 7 months growth in the nursey. 相似文献
999.
Summary The sensitivity of the mineralization of nitrogen by a range of soils contaminated with heavy metals (up to 340 μg Cd g−1, 7500 μg Pb g−1 and 34000 μg Zn g−1) to the addition of heavy metals in solution were studied using pot incubations (ammonification) and a soil perfusion technique
(nitrification). The ammonification of peptone showed little correlation between treatments with Cd, Zn (1000 and 5000 μg
g−1) and Pb (10000 and 20000 μg g−1) and origin of the soil. Nitrification was considerably more sensitive to heavy metals than ammonification. All the soils
had active, often large, populations of ammonifying and nitrifying organisms which showed substantial similarities between
the soils. The rate of nitrifying activity (NO3−N production) was logrithmic in most cases. The presence of tolerant populations of nitrifying organisms in the contaminated
soils was demonstrated. Tolerance was also eventually acquired after a longer lag phase, by the non-contaminated soil populations
although the rate of activity was often reduced. Metals added in solution were adsorbed by the soil within 4 hours. Differences
in toxicity between metal salts (chlorides, sulphates and acetate) were attributed to the amount left in solution. However,
in many instances, acetate was found to stimulate all the stages in the mineralisation of nitrogen. 相似文献
1000.
Summary The uptake of trace metals by two plant species (French bean and maize) has been measured on two soils subjected to various waterlogging regimes. Uptake of both manganese and iron was increased due to soil waterlogging, although reoxidation of the soil affected iron more than manganese. Zinc and copper uptake was influenced by a species factor; French bean (Phaseolus vulgaris) showed preferential uptake of zinc, whereas maize (Zea mays) took up copper preferentially. Uptake of cobalt by both species was increased due to waterlogging, following the pattern of manganese.The abilities of these species to take up trace metals from soil followed the pattern predicted by selective extraction of soil for manganese, iron and cobalt, but not for zinc and copper. 相似文献