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111.
The impact of land use and land cover change on biodiversity within and adjacent to Kibasira Swamp in Kilombero Valley,Tanzania 下载免费PDF全文
Hamidu A. Seki Deo D. Shirima Colin J. Courtney Mustaphi Rob Marchant Pantaleo K. T. Munishi 《African Journal of Ecology》2018,56(3):518-527
Wetlands are crucial ecosystems with multiple values and functions to a range of different stakeholders. The future of wetlands depends both on the legacy of the past and how they are currently used. Using 48 vegetation survey plots (0.08 ha) combined with Landsat 5 and 7 TM imagery, we assessed the influence of long‐term (1990–2011) land use and land cover change on the biodiversity of the Kibasira Swamp. Information on perceptions of adjacent communities on historical changes and drivers for the changes were also collected. Results showed an increase in the area covered by open water by 1% and forest by 4% between 1990 and 1998 whilst Cyperus papyrus L and cultivated land area decreased by 8% and 3%, respectively on the same period. Between 1998 and 2011, there was a decrease in areas covered by water by 35% and forest by 9% whereas C. papyrus L increased by 40% and cultivated land increased by 8%. These changes have affected the biodiversity of the swamp and adjacent to it as numbers of mammals have declined. However, the Swamp still provides extensive habitat for plants and bird species despite the ongoing human pressure. Interventions may be necessary to maintain biodiversity in Kibasira Swamp to ensure sustainable ecosystem services. 相似文献
112.
A unique polypeptide, called enhancing factor (EF), which enhances the binding of labeled epidermal growth factor (EGF) to cells, has been isolated. It has been purified to homogeneity from the acid-soluble proteins of mouse intestines. Earlier, EF was partially purified by two cycles of gel-permeation chromatography on Bio-Gel columns. We now report the final purification of EF on high-performance liquid chromatography (HPLC), using a reverse-phase column (mu Bondapak C18). The purity of the protein was confirmed when a single peak was obtained in HPLC. Also, a single protein band was obtained in SDS-PAGE. Purified EF has the same properties in vitro as those reported earlier for partially purified EF. 相似文献
113.
Kim A Deo SH Vianna LC Balanos GM Hartwich D Fisher JP Fadel PJ 《American journal of physiology. Heart and circulatory physiology》2011,301(6):H2454-H2465
It is presently unknown whether there are sex differences in the magnitude of blood pressure (BP) responses to baroreceptor perturbation or if the relative contribution of cardiac output (CO) and total vascular conductance (TVC) to baroreflex-mediated changes in BP differs in young women and men. Since sympathetic vasoconstrictor tone is attenuated in women, we hypothesized that carotid baroreflex-mediated BP responses would be attenuated in women by virtue of a blunted vascular response (i.e., an attenuated TVC response). BP, heart rate (HR), and stroke volume were continuously recorded during the application of 5-s pulses of neck pressure (NP; carotid hypotension) and neck suction (NS; carotid hypertension) ranging from +40 to -80 Torr in women (n = 20, 21 ± 0.5 yr) and men (n = 20, 21 ± 0.4 yr). CO and TVC were calculated on a beat-to-beat basis. Women demonstrated greater depressor responses to NS (e.g., -60 Torr, -17 ± 1%baseline in women vs. -11 ± 1%baseline in men, P < 0.05), which were driven by augmented decreases in HR that, in turn, contributed to larger reductions in CO (-60 Torr, -15 ± 2%baseline in women vs. -6 ± 2%baseline in men, P < 0.05). In contrast, pressor responses to NP were similar in women and men (e.g., +40 Torr, +14 ± 2%baseline in women vs. +10 ± 1%baseline in men, P > 0.05), with TVC being the primary mediating factor in both groups. Our findings indicate that sex differences in the baroreflex control of BP are evident during carotid hypertension but not carotid hypotension. Furthermore, in contrast to our hypothesis, young women exhibited greater BP responses to carotid hypertension by virtue of a greater cardiac responsiveness. 相似文献
114.
The usual analysis of quantal response data occurring in diverse fields such as economics, medicine, psychology and toxicology use probit and logit models or their extensions with generalised least squares or the principle of likelihood as the method of statistical inference. The quantal method was first used for estimation of agricultural production by S. M. Vidwans (1991). He has collected the data on yield rate of rabi jowar from the farmers for year 1981 in four villages in Shirur taluka and three villages in Daund taluka of Pune district of Maharashtra in India. The probit regression line is fitted. The fit is not good. The estimation is done using truncation of data. Here we observed that a second degree polynomial is a good fit to the data. This will give correct prediction of agricultural production with smaller standard error. 相似文献
115.
116.
Nested areas of endemism analysis 总被引:1,自引:0,他引:1
Aim To develop and evaluate a nested clade approach to aid in the determination of areas of endemism (AoE) in biogeographical studies.
Methods We adapted the nested clade analysis (NCA) to studies of areas of endemism. For this purpose we adapted several of the programs currently in use. Two data sets were examined using this approach – one involving Sciobius in southern Africa and the other involving terrestrial mammals in Mexico.
Results Nested clade analysis as applied to areas of endemism produced results similar to those of previous analyses of Sciobus in southern Africa. An analysis of terrestrial mammals in Mexico supports the designation of some biogeographical provinces as areas of endemism while suggesting that other provinces may comprise composite distributions that should be subdivided.
Main conclusions The nested clade analysis approach utilized primarily in genetic analysis of phylogeographical patterns in population biology studies can be adapted to understanding AoE in the realm of biogeography. This approach offers a statistical paradigm to evaluate AoE suggested by parsimony analysis of endemicity (PAE) trees. 相似文献
Methods We adapted the nested clade analysis (NCA) to studies of areas of endemism. For this purpose we adapted several of the programs currently in use. Two data sets were examined using this approach – one involving Sciobius in southern Africa and the other involving terrestrial mammals in Mexico.
Results Nested clade analysis as applied to areas of endemism produced results similar to those of previous analyses of Sciobus in southern Africa. An analysis of terrestrial mammals in Mexico supports the designation of some biogeographical provinces as areas of endemism while suggesting that other provinces may comprise composite distributions that should be subdivided.
Main conclusions The nested clade analysis approach utilized primarily in genetic analysis of phylogeographical patterns in population biology studies can be adapted to understanding AoE in the realm of biogeography. This approach offers a statistical paradigm to evaluate AoE suggested by parsimony analysis of endemicity (PAE) trees. 相似文献
117.
118.
Plutonium (Pu), a key contaminant at sites associated with the manufacture of nuclear weapons and with nuclear-energy wastes,
can be precipitated to “immobilized” plutonium phases in systems that promote bioreduction. Ferric iron (Fe3+) is often present in contaminated sites, and its bioreduction to ferrous iron (Fe2+) may be involved in the reduction of Pu to forms that precipitate. Alternately, Pu can be reduced directly by the bacteria.
Besides Fe, contaminated sites often contain strong complexing ligands, such as nitrilotriacetic acid (NTA). We used biogeochemical
modeling to interpret the experimental fate of Pu in the absence and presence of ferric iron (Fe3+) and NTA under anaerobic conditions. In all cases, Shewanella alga BrY (S. alga) reduced Pu(V)(PuO2
+) to Pu(III), and experimental evidence indicates that Pu(III) precipitated as PuPO4(am). In the absence of Fe3+ and NTA, reduction of PuO2
+ was directly biotic, but modeling simulations support that PuO2
+ reduction in the presence of Fe3+ and NTA was due to an abiotic stepwise reduction of PuO2
+ to Pu4+, followed by reduction of Pu4+ to Pu3+, both through biogenically produced Fe2+. This means that PuO2
+ reduction was slowed by first having Fe3+ reduced to Fe2+. Modeling results also show that the degree of PuPO4(am) precipitation depends on the NTA concentration. While precipitation out-competes complexation when NTA is present at the
same or lower concentration than Pu, excess NTA can prevent precipitation of PuPO4(am). 相似文献
119.
Pradeep C. Deo Mary Taylor Robert M. Harding Anand P. Tyagi Douglas K. Becker 《Plant Cell, Tissue and Organ Culture》2010,100(3):283-291
Embryogenic callus was initiated by culturing in vitro taro corm slices on agar-solidified half-strength MS medium containing
2.0 mg/L 2,4-dichlorophenoxyacetic acid (2,4-D) for 20 days followed by transfer to 1.0 mg/L thidiazuron (TDZ). Callus was
subsequently proliferated on solid medium containing 1.0 mg/L TDZ, 0.5 mg/L 2,4-D and 800 mg/L glutamine before transfer to
liquid medium containing the same components but with reduced glutamine (100 mg/L). After 3 months in liquid culture on an
orbital shaker, cytoplasmically dense cell aggregates began to form. Somatic embryogenesis was induced by plating suspension
cells onto solid media containing reduced levels of hormones (0.1 mg/L TDZ, 0.05 mg/L 2,4-D), high concentrations of sucrose
(40–50 g/L) and biotin (1.0 mg/L). Embryo maturation and germination was then induced on media containing 0.05 mg/L benzyladenine
(BA) and 0.1 mg/L indole-3-acetic acid (IAA). Histological studies of the developing embryos revealed the presence of typical
shoot and root poles suggesting that these structures were true somatic embryos. The rate of somatic embryos formation was
500–3,000 per mL settled cell volume while approximately 60% of the embryos regenerated into plants. 相似文献