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131.
Danaë M. A. Rozendaal Robin L. Chazdon Felipe Arreola-Villa Patricia Balvanera Tony V. Bentos Juan M. Dupuy J. Luis Hernández-Stefanoni Catarina C. Jakovac Edwin E. Lebrija-Trejos Madelon Lohbeck Miguel Martínez-Ramos Paulo E. S. Massoca Jorge A. Meave Rita C. G. Mesquita Francisco Mora Eduardo A. Pérez-García I. Eunice Romero-Pérez Irving Saenz-Pedroza Michiel van Breugel G. Bruce Williamson Frans Bongers 《Ecosystems》2017,20(2):340-353
The magnitude of the carbon sink in second-growth forests is expected to vary with successional biomass dynamics resulting from tree growth, recruitment, and mortality, and with the effects of climate on these dynamics. We compare aboveground biomass dynamics of dry and wet Neotropical forests, based on monitoring data gathered over 3–16 years in forests covering the first 25 years of succession. We estimated standing biomass, annual biomass change, and contributions of tree growth, recruitment, and mortality. We also evaluated tree species’ contributions to biomass dynamics. Absolute rates of biomass change were lower in dry forests, 2.3 and 1.9 Mg ha?1 y?1, after 5–15 and 15–25 years after abandonment, respectively, than in wet forests, with 4.7 and 6.1 Mg ha?1 y?1, in the same age classes. Biomass change was largely driven by tree growth, accounting for at least 48% of biomass change across forest types and age classes. Mortality also contributed strongly to biomass change in wet forests of 5–15 years, whereas its contribution became important later in succession in dry forests. Biomass dynamics tended to be dominated by fewer species in early-successional dry than wet forests, but dominance was strong in both forest types. Overall, our results indicate that biomass dynamics during succession are faster in Neotropical wet than dry forests, with high tree mortality earlier in succession in the wet forests. Long-term monitoring of second-growth tropical forest plots is crucial for improving estimates of annual biomass change, and for enhancing understanding of the underlying mechanisms and demographic drivers. 相似文献
132.
Mohamed N. Sallam William A. Overholt Eunice Kairu 《Biocontrol Science and Technology》2002,12(4):493-506
Super and multiple parasitism of Chilo partellus (Lepidoptera: Pyralidae) and Sesamia calamistis (Lepidoptera: Noctuidae) by Cotesia flavipes Cameron and Cotesia sesamiae (Cameron) (Hymenoptera: Braconidae) were investigated in the laboratory. Progeny production of Co. flavipes increased as a result of increasing the number of ovipositions, from one to three per one Ch. partellus host larva, then decreased as a result of four and five ovipositions per larva. Cocoon weight, sex ratio and emergence of the parasitoid progeny were not affected by superparasitism. Low progeny production of Co. sesamiae and poor survival of Ch. partellus host larvae were found as a result of superparasitism. When S. calamistis was the host, the duration of immature stages of Co. flavipes , parasitoid emergence, progeny production and sex ratio were not affected by superparasitism, but cocoon weight, adult longevity and the potential fecundity of adult females decreased. Superparasitism of S. calamistis by Co. sesamiae did not affect emergence, longevity or sex ratio of adult progeny of the parasitoid, but prolonged immature development, lowered cocoon weight and decreased potential fecundity of adult female progeny. Co. flavipes out-competed Co. sesamiae when Ch. partellus was parasitized by both species. The potential for local displacement of Co. sesamiae by Co. flavipes in areas dominated by Ch. partellus in East Africa is discussed. 相似文献
133.
Depressed mood in severely obese, bariatric surgery-seeking candidates is influenced by obesity stigma, yet the strategies for coping with this stigma are less well understood. This study hypothesized that coping strategies are significantly associated with depressed mood above and beyond demographic factors and frequency of weight-related stigma, with specific coping strategies differing between racial groups. Severely obese, bariatric surgery-seeking adults (N = 234; 91 African Americans) completed the Beck Depression Inventory (BDI) and Stigmatizing Situations Inventory (SSI). Two hierarchical linear regressions were conducted separately for African Americans and whites. For both racial groups, age, sex, BMI, years overweight, annual income, and education level did not account for a significant portion of the variance in BDI scores. The frequency of stigmatizing situations and coping strategies significantly explained 16.4% and 33.2%, respectively, of the variance for whites, and 25.9% and 25%, respectively, for African Americans (P < 0.001). Greater depressed mood in whites was associated with older age, lower education, fewer positive self-statements, and less self-love and more crying; while in African Americans greater depressed mood was associated only with ignoring the situation (P < 0.05). The study found that regardless of race, depressed mood in severely obese, bariatric surgery-seeking clients is related to the frequency of stigmatizing experiences and associated coping strategies. This suggests that efforts to reduce the deleterious effects of weight-related stigma need to focus both on reducing the frequency of stigmatization and on teaching effective coping strategies. These efforts also need to take into account the client's racial background. 相似文献
134.
James CD Reuel N Lee ES Davalos RV Mani SS Carroll-Portillo A Rebeil R Martino A Apblett CA 《Biosensors & bioelectronics》2008,23(6):845-851
We report here a non-invasive, reversible method for interrogating single cells in a microfluidic flow-through system. Impedance spectroscopy of cells held at a micron-sized pore under negative pressure is demonstrated and used to determine the presence and viability of the captured cell. The cell capture pore is optimized for electrical response and mechanical interfacing to a cell using a deposited layer of parylene. Changes in the mechanical interface between the cell and the chip due to chemical exposure or environmental changes can also be assessed. Here, we monitored the change in adhesion/spreading of RAW264.7 macrophages in response to the immune stimulant lipopolysaccharide (LPS). This method enables selective, reversible, and quantitative long-term impedance measurements on single cells. The fully sealed electrofluidic assembly is compatible with long-term cell culturing, and could be modified to incorporate single cell lysis and subsequent intracellular separation and analysis. 相似文献
135.
Eunice Judith Cardoso de Almeida Cecília Mikie Yamada Eudoxia Maria Froehlich 《Hydrobiologia》1991,227(1):169-173
The chromosome complement and the C-banded karyotypes of specimens of Geoplana marginata auct. and of Issoca rezendei (Schirch) were investigated. The diploid and fundamental numbers of the two species were identical (2n = 14; FN = 28). Their karyotypes were similar except for the morphology of chromosome pair 6. Their C-banding patterns differed in quantity and localization of the constitutive heterochromatin. The similarity in karyotypes of these species support the hypothesis, proposed earlier on morphological grounds, that the genera Geoplana Stimpson and Issoca Froehlich are closely related. G. marginata and I. rezendei are the first land planarian species of the Neotropical Region to have their karyotypes described. 相似文献
136.
Flusberg BA Cocker ED Piyawattanametha W Jung JC Cheung EL Schnitzer MJ 《Nature methods》2005,2(12):941-950
Optical fibers guide light between separate locations and enable new types of fluorescence imaging. Fiber-optic fluorescence imaging systems include portable handheld microscopes, flexible endoscopes well suited for imaging within hollow tissue cavities and microendoscopes that allow minimally invasive high-resolution imaging deep within tissue. A challenge in the creation of such devices is the design and integration of miniaturized optical and mechanical components. Until recently, fiber-based fluorescence imaging was mainly limited to epifluorescence and scanning confocal modalities. Two new classes of photonic crystal fiber facilitate ultrashort pulse delivery for fiber-optic two-photon fluorescence imaging. An upcoming generation of fluorescence imaging devices will be based on microfabricated device components. 相似文献
137.
Eunice C. Schuytema Martha P. Hargie Donald J. Siehr Ilmar Merits Jay R. Schenck Muriel S. Smith Estie L. Varner 《Applied microbiology》1963,11(3):256-259
A total of 254 basidiomycete cultures have been examined for their action on progesterone. Of these, 54 showed transformation products by thin-film and gas-liquid chromatography. The major product formed by eight of these organisms acting on progesterone has been isolated and identified. 相似文献
138.
139.
Red Blood Cell Folate Insufficiency among nonpregnant Women of Childbearing age in Guatemala 2009 to 2010: Prevalence and predicted Neural Tube Defects risk 下载免费PDF全文
140.
Julio Cesar Torres Elguera Eunice Yañez Barrientos Kazimierz Wrobel Katarzyna Wrobel 《Acta Physiologiae Plantarum》2013,35(2):431-441
The purpose of this study was to investigate the effects of cadmium [Cd(II) as cadmium chloride], selenium [Se(IV) as sodium selenite] and their mixtures on phenolic compounds (PCs) and antioxidant activity (AOx) in Lepidium sativum. The biomass fractions corresponding to free (F1), soluble glycoside-bound (F2) and cell wall ester-bound phenolics (F3) were obtained for each treatment and PCs were screened by gas chromatography (GC-FID); F1 and F2 fractions were also analyzed by liquid chromatography with UV and fluorimetric detection. The treated plants presented different profiles of PCs as compared to controls, specifically in F1 and F2 fractions; the plant response was element-, and concentration-dependent. The cultures challenged with Cd(II) up to 5 mg L?1, presented higher AOx with respect to controls, and this increase was associated with glycoside-bound PCs, whereas for Se(IV) the increase of AOx was less marked and associated with free PCs. Under simultaneous exposure to Cd(II) + Se(IV) (0.5–2.0 mg L?1 each), the AOx values were relatively constant and lower than those found in the presence of Se(IV) or Cd(II) alone, providing further evidence of the protective role of Se(IV) against stress imposed by Cd(II) in this plant species. The evaluation of AOx of individual PCs and the results of principal component analysis enabled to attain several relationships among exposure conditions, antioxidant activity, free- and glycoside-bound phenolic compounds. 相似文献