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81.
Agnieszka Sujak 《Acta Physiologiae Plantarum》2005,27(1):61-69
This paper reports the results of research on the interaction between the cytochrome f of the active cytochrome b
6
f complex (incubated with Cd-, Zn-, and Ag-substituted plastocyanins) and Cu-plastocyanin. The presented studies show, that
the metal derivatives of plastocyanin can have an influence on the photosynthetic electron transfer path: cytochrome b
6
f complex — photosystem I. The metal-substituted plastocyanins occupy the plastocyanin electron transfer site of the cytochrome
f. The stopped-flow measurements show, that although the metal derivatives of plastocyanin do not influence the rate of cyt
f- Pc electron transfer, creation of the non-electron-transfer complexes characterised by a strong binding between the cyt
f and substituted plastocyanins and their slow release, dependent on the redox state of the substituted metal, results in the
decrease of a turnover of the cytochrome complex.
The research was done in the Department of Plant Biochemistry, Freiburg University, Sch?nzlestrasse 1, 79 104 Freiburg, Germany 相似文献
82.
Viera Banásová Othmar Horak Milada Čiamporová Miriam Nadubinská Irene Lichtscheidl 《Biologia》2006,61(4):433-439
We investigated the composition of the vegetation in two former mining regions in Central Slovakia: Banská Štiavnica with
predominant Pb-Zn contamination and Staré Hory with a very high Cu content in the soil. Old heaps rich in heavy metals are
covered with specific vegetation. On the Cu-rich spoil heaps, species-poor plant communities with prevailing Agrostis stolonifera, Avenella flexuosa, Acetosella vulgaris, Arabidopsis arenosa, Silene dioica, and S. vulgaris occur. Species such as Agrostis capillaris, Acetosella vulgaris, Arabidopsis arenosa, and Thlaspi caerulescens appear frequently on Pb-Zn mine wastes. Several differences in the vegetation structure were detected between the Pb-Zn and
Cu mine heaps; higher amounts of vascular plants and fewer lichen species covered the Pb-Zn mine heaps. For the Cu mine heaps,
on the contrary a small number of vascular species but a high number and coverage of lichen species, especially Ceratodon purpureus and Cladonia arbuscula subsp. mitis were typical. The non-metalliferous meadows in the vicinity of the mines showed uniform structure but a higher species diversity. 相似文献
83.
Effect of nickel on antioxidative enzyme activities, proline and chlorophyll contents in wheat shoots 总被引:12,自引:0,他引:12
Effect of two Ni concentrations (10 and 200 μM) on growth, Ni accumulation, chlorophyll and proline contents, relative water
content (RWC) as well as the activities of superoxide dismutase (SOD), catalase (CAT), peroxidase (POD) and glutathione S-transferase
(GST) were studied in shoots of wheat plants. Treatments caused a considerable accumulation of Ni in the shoots. However,
exposure of plants to 10 μM Ni did not lead to significant alterations in shoot growth except for a slight increase in fresh
mass. The other parameters studied were not affected by treatment of plants with 10 μM Ni. In contrast, 200 μM Ni caused inhibition
of shoot growth, a decline in RWC and chlorophyll content, accumulation of proline and occurrence of visible symptoms of Ni
toxicity. The activities of SOD and CAT decreased in response to 200 μM Ni. Conversely, several-fold enhancements of POD and
GST activities were observed following the 3rd day of 200 μM Ni treatment. 相似文献
84.
Michael S. Ross Sherry Mitchell-Bruker Jay P. Sah Stuart Stothoff Pablo L. Ruiz David L. Reed Kris Jayachandran Charles L. Coultas 《Hydrobiologia》2006,569(1):37-59
Extensive portions of the southern Everglades are characterized by series of elongated, raised peat ridges and tree islands
oriented parallel to the predominant flow direction, separated by intervening sloughs. Tall herbs or woody species are associated
with higher elevations and shorter emergent or floating species are associated with lower elevations. The organic soils in
this “Ridge-and-Slough” landscape have been stable over millennia in many locations, but degrade over decades under altered
hydrologic conditions. We examined soil, pore water, and leaf phosphorus (P) and nitrogen (N) distributions in six Ridge and
Slough communities in Shark Slough, Everglades National Park. We found P enrichment to increase and N to decrease monotonically
along a gradient from the most persistently flooded sloughs to rarely flooded ridge environments, with the most dramatic change
associated with the transition from marsh to forest. Leaf N:P ratios indicated that the marsh communities were strongly P-limited,
while data from several forest types suggested either N-limitation or co-limitation by N and P. Ground water stage in forests
exhibited a daytime decrease and partial nighttime recovery during periods of surface exposure. The recovery phase suggested
re-supply from adjacent flooded marshes or the underlying aquifer, and a strong hydrologic connection between ridge and slough.
We therefore developed a simple steady-state model to explore a mechanism by which a phosphorus conveyor belt driven by both
evapotranspiration and the regional flow gradient can contribute to the characteristic Ridge and Slough pattern. The model
demonstrated that evapotranspiration sinks at higher elevations can draw in low concentration marsh waters, raising local
soil and water P concentrations. Focusing of flow and nutrients at the evapotranspiration zone is not strong enough to overcome
the regional gradient entirely, allowing the nutrient to spread downstream and creating an elongated concentration plume in
the direction of flow. Our analyses suggest that autogenic processes involving the effects of initially small differences
in topography, via their interactions with hydrology and nutrient availability, can produce persistent physiographic patterns
in the organic sediments of the Everglades. 相似文献
85.
高等植物金属抗性中有机酸的作用及其机理 总被引:2,自引:0,他引:2
植物的金属抗性可通过避性和耐性途径获得。具有螯合能力的有机酸在植物的金属外部排斥(避性)机制和内部耐受(耐性)机制中均具有重要作用。在金属的外部排斥过程中,植物根系分泌有机酸,与金属离子形成稳定的复合体,降低土壤金属的移动性,达到体外解毒的目的。超积累型植物的内部耐受机制主要体现在,有机酸可与金属元素发生螯合作用,将离子态的金属转变成低毒或无毒的螯合态,从而降低细胞内金属离子的毒害效应。有机酸的种类受植物种类、金属类型等因素的影响。 相似文献
86.
模拟酸雨对污泥堆肥中重金属形态转化及其环境行为的影响 总被引:12,自引:0,他引:12
通过模拟酸雨淋溶土柱的方法,研究了酸雨(pH=5.0和2.9)作用下污泥堆肥中Zn、Cu和Ni的溶出和迁移性。分析了酸雨对重金属形态分布规律的影响。结果表明,在相同酸雨强度下,淋出液中重金属含量与其在土柱中迁移距离大小次序为Zn〉Cu〉Ni;重金属在相同深度的土层中含量大小次序为Zn〉Ni〉Cu。淋溶液pH的降低和污泥堆肥施加比例的提高均会增加重金属在淋出液和土柱中的含量,但不影响重金属在土柱中的迁移距离。土壤酸化会促使土壤中重金属形态向活性形态转化,而且迁移距离增加。 相似文献
87.
88.
89.
Jean-Pierre Djukic 《Inorganica chimica acta》2006,359(6):1754-1760
The reaction of a chiral terpenic 2-phenylpyridine with mercury (II) acetate afforded a new ortho-chloromercurated substrate, which was treated with [(η6-cymene)RuCl2]2 to afford two diastereomers of the corresponding half-sandwich cyclochlororuthenated terpenic ligand. The latter two complexes were successfully separated by conventional chromatography and their configurational stability investigated by 1H NMR and CD spectroscopy. It was found that both isolated diastereomers displayed a fair configurational stability in CH2Cl2 while when dissolved in MeOH they epimerize. It was shown that the rate of epimerization is rather slow in pure MeOH, whereas in the presence of an excess of Lewis acid such as HgCl2 it was notably accelerated suggesting that the decoordination of the chloride from the Ru(II) center is a key step in the epimerization process. 相似文献
90.
Leaching potential of heavy metals (Cd, Ni, Pb, Cu and Zn) from acidic sandy soil amended with dolomite phosphate rock (DPR) fertilizers 总被引:2,自引:0,他引:2
G.C. Chen Z.L. He P.J. Stoffella X.E. Yang S. Yu J.Y. Yang D.V. Calvert 《Journal of trace elements in medicine and biology》2006,20(2):127-133
There is an increasing concern on heavy metal leaching from the soils amended with sewage sludge. A column study was conducted to examine the extent of leaching of five important heavy metals (Cd, Ni, Pb, Cu and Zn) from an acidic sandy soil amended with different dolomite phosphate rock (DPR) fertilizers (an application rate of 1% fertilizers) developed from DPR and N-Viro (consisting of biosolids and fly ash) at 0%, 10%, 20%, 30%, 40%, 50% and 100% DPR. Ten leaching events were carried out with each event done at an interval of 7 days and with total leaching volume of 1183mm, which is equivalent to the mean annual rainfall of this region during the period of 2001-2003. Leachate was collected after each leaching event and analyzed for heavy metals. The maximum leachate concentrations of Cd, Ni, Pb, Cu and Zn were all below drinking water quality guidance limits set by Florida Department of Environmental Protection and World Health Organization, suggesting that the application of DPR fertilizers may not pose a threat to water quality by leaching. Most of leachate concentrations of Cd, Ni and Pb were below their detection limits and there were no significant differences between the control and the treatments with different DPR fertilizers. By contrast, there were higher leachate concentrations of Cu and Zn (ranging from 0.7 to 37.1mug Cu/l and 5.1 to 205.6mug Zn/l for all treatments) due to their higher contents in both the soil and different DPR fertilizers compared with Cd, Ni and Pb. The leachate concentrations of Cu and Zn for each treatment decreased with increasing leaching events. The differences in leachate concentrations of Cu and Zn between the control and the treatments with different DPR fertilizers containing N-Viro were significant, especially in the first several leaching events and, moreover, they increased with increasing proportion of N-Viro in the DPR fertilizers. There were similar trends in total losses of Cu and Zn after ten leaching events. Greater differences in both leachate concentrations and total losses of Zn between the control and the treatments containing N-Viro were noted. Total losses of Zn for the treatments containing N-Viro were 3.0-5.1 times higher than those for the control compared with 1.4-2.2 times higher for total losses of Cu, suggesting that greater proportions of Zn losses came from the DPR fertilizers due to the greater mobility of Zn in the DPR fertilizers compared with Cu. 相似文献