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排序方式: 共有124条查询结果,搜索用时 15 毫秒
1.
Teresa Conde 《Preparative biochemistry & biotechnology》2016,46(4):406-409
In this study, a new method for isolation of polyphenols (PP) from spent coffee grounds (SCG) and coffee silverskin (CS) is described. The method consisted of a mild hydrothermal pretreatment at 120°C, for 20 min, using a liquid-to-solid ratio of 20 mL/g. PP (determined as gallic acid equivalents, GAE) were the most abundant components in the extracts produced by this method, corresponding to 32.92 mgGAE/gSCG and 19.17 mgGAE/gCS, among which flavonoids corresponded to 8.29 and 2.73 mg quercetin equivalents/g of SCG and CS, respectively. Both extracts presented antioxidant activity but the results were higher for SCG extract, probably due to the highest content of PP present. Negligible effects (less than 1% solubilization) were caused by the hydrothermal pretreatment on cellulose, hemicellulose, and protein fractions of these materials. Some mineral elements were present in the extracts, with potassium being the most abundant. Hydrothermal pretreatment under mild conditions was demonstrated to be an efficient method to recover antioxidant PP from coffee residues. 相似文献
2.
2004年12月至2005年3月在北京十渡地区的二渡和涞水县野三坡两地采用目标取样法对越冬期黑鹳(Ciconia nigra)的取食行为进行了观察。每星期观察一次,累计观察246 h。黑鹳觅食处水深5~40 cm左右,以鱼类和螺类为食,其中鱼类占90%以上;平均每小时进食20次左右,黑鹳在两个研究地点取食的食物没有差别(P=0.439>0.05)。黑鹳取食长度小于4 cm的鱼类最多,占取食总次数的65.0%。成体和亚成体对不同大小鱼类的取食比例无差异(小于4 cm的鱼类,P=0.513>0.05;5~8 cm,P=0.979>0.05;≥9 cm,P=0.657>0.05)。在成体与亚成体对不同体型鱼类的搜寻时间中,成体搜寻较小食物的时间短于亚成体(P=0.008<0.05)。对食物的处理时间随着鱼类大小递增而延长,亚成体在处理较小食物上花费的时间相对较长(小于4 cm的鱼P=0.002<0.05;5~8cm的鱼P=0.001<0.05),表明亚成体的取食经验不足。保护越冬期黑鹳的最佳对策是减少对其取食活动和取食地的人为干扰。 相似文献
3.
Kenneth J. Saville Andrea M. Lindley Eleanora G. Maries Jeffrey C. Carrier Harold L. Pratt Jr. 《Environmental Biology of Fishes》2002,63(3):347-351
For over a decade, we have been studying the reproductive behavior of the nurse shark, Ginglymostoma cirratum, in the Dry Torugas off the Florida Keys, an important mating and nursery ground for this species. In the course of these studies, we have used a variety of tags and tagging protocols to monitor individual animals. Here we report the use of molecular methods for the genetic analysis of nurse sharks. Specifically we have analyzed genetic variation at the MHC II alpha locus using the polymerase chain reaction (PCR) followed by restriction fragment length polymorphism (RFLP) analysis of the amplified products. We found this technique to be a relatively rapid and reliable method for identifying genetic differences between individual sharks. Applying this method to a family of sharks consisting of a mother and 32 pups, we demonstrate that at least four fathers must have fathered this brood. Multiple paternity in the nurse shark suggests a mechanism by which populations of this species may maximize genetic variability. This seems especially valuable for philopatric species whose migratory movement, and thus potential for genetic diversity, is limited. 相似文献
4.
William M. Gilbert 《Ecology and evolution》2022,12(3)
I made observations of a central California population of Wilson''s Warbler, Cardellina pusilla, after July 1 over 10 breeding seasons. I sighted males in definitive prebasic molt from July 4 (in 2007) to September 1 (in 1999). Most territorial males molted on their breeding territories, and individual molt lasted up to 46 days. Following prebasic molt, territorial males engaged in subdued “post‐molt singing,” which lasted about 7 days in some males, and which I first heard on August 13 (in 2004) and last heard on September 6 (in 1999). I sighted no female in definitive prebasic molt, or in fresh basic plumage, during the study. Of 13 females sighted ≥ July 21, 11 were in late breeding season uniparental brood care, and I could not rule out late brood care for the other two. Most, and possibly all, females not engaged in late season uniparental brood care apparently vacated their breeding territories before July 21. This departure was much earlier than for resident males, the last of which I sighted on September 10 (in 1999). Early‐departing females presumably underwent prebasic molt after July 21 at locations not known. Remaining late‐nesting females must have molted much later than resident males and likely later than early‐departing females, and at locations unknown. I last sighted two uniparental brood‐tending females, still in worn plumage, on August 26 and 29, respectively. Two unique findings of this study are a male/female difference in location of prebasic molt, and a likely dichotomy of prebasic molt timing between females leaving their breeding territories early and those remaining in uniparental brood care. Another finding, post‐molt singing in most and possible all territorial males, is a largely unrecognized behavior, but one previously reported in several passerine species. Post‐molt singing may reliably indicate completion of prebasic molt. 相似文献
5.
大鸨(Otis tarda)属大型草原鸟类,过去曾广泛分布于黑龙江省西部及内蒙古的东部,目前已经处于濒危状态。图牧吉自然保护区是大鸨的主要栖息地,繁殖数量约200多只。1998年开始记录到越冬大鸨个体,2003年冬季,本区越冬数量达到165只(其中保护区内记录到85只)。本文对图牧吉自然保护区大鸨的越冬数量分布进行了调查,并对大鸨越冬行为及食性进行了初步的观察和分析,对大鸨越冬地管理及越冬鸟类的保护提出了建议。 相似文献
6.
7.
Although there is a general understanding of Montagu’s harriers migration routes and wintering areas, detailed information
on the species’ migration is still lacking. However, improvements in satellite tracking technology in recent years, have enabled
the study of medium-sized species by means of satellite telemetry. In 2006, ten adult Montagu’s harriers were fitted with
satellite transmitters in northeastern Spain and tracked during their autumn migration to their wintering grounds in sub-Saharan
Africa. The migration took between 10 and 30 days, and the end point was determined using breakpoint regressions. Whereas
some birds had stopovers of more than a week, others stayed at the same site for only 1 or 2 days at the most. The tagged
birds ultimately established at wintering grounds located along the border of Mauritania with Mali and Senegal, a distance
of nearly 3000 km from the breeding sites. These sites are situated within a small range of latitudes (14° and 17°N), although
distributed over a wider range of longitudes (−15°E and −4°E), with some birds occupying sites more than 1000 km apart. The
distance covered in 1 day during the migration ranged between 93 and 219 km, with peaks of traveling speed of up to 65 km/h.
Harriers were recorded traveling only during daytime, covering the longest distances in the late afternoon, suggesting that
they are daytime migrants. Most of the distance was covered between 1500 and 2000 hours, and no traveling was recorded between
2000 and 0500 hours. During migration, harriers flew close to the ground (40–100 m on average). Improved knowledge of the
harriers’ exact wintering sites may provide insights on the problems Montagu’s harriers face during the winter, highlighting
the need to take into account what happens in both the breeding and wintering grounds to implement successful conservation
measures. 相似文献
8.
Valerie Chosson;Virginie Wyss;Beatrice Jann;Frederick W. Wenzel;Guðjón Már Sigurðsson;Malene Simon;Rikke Guldborg Hansen;Lindsey S. Jones; 《Ecology and evolution》2024,14(3):e11152
The endangered population of humpback whales (Megaptera novaeangliae) breeding and calving off the Cape Verde Islands (CVI) are known to migrate to feeding areas located along the eastern margin of the North Atlantic Ocean (Iceland, and Norway). Here, we report for the first time a confirmed migration of an individual humpback whale from CVI breeding ground to a western North Atlantic feeding ground of West Greenland. This individual humpback, which was photographed and identified off the coast of West Greenland in 2021, was previously documented in CVI 22 years before (1999). An annual subsistence hunt for humpbacks occurs in West Greenland and the resighting at this location with a humpback whale from CVI has strong implications for the conservation efforts of the small CVI population. 相似文献
9.
The distributions of larval and juvenile fishes in Amazonian rivers of different nutrient status 总被引:1,自引:0,他引:1
1. Previous work has indicated, at least in two river systems, that some Characiformes species migrate from nutrient‐poor rivers to spawn in nutrient‐rich rivers. In the present work, larval and juvenile fish were surveyed to index spawning activity in order to determine whether this spawning pattern is repeated in nine major tributaries of the Amazon basin. 2. Adult Mylossoma aureum, M. duriventre, Colossoma macropomum, Anodus elongatus, Triportheus elongatus, Brycon cephalus, Semaprochilodus insignis, S. taeniurus and Prochilodus nigricans were recorded in nutrient‐poor and nutrient‐rich rivers. However, larval and juvenile individuals of these species were found in nutrient‐rich rivers only, indicating that spawning activity was restricted to that river type. 3. Concentration of suspended solids in the river was correlated with total ichthyoplankton density and related to species composition of juvenile characiform assemblages. 4. Our findings reinforce the hypothesis that nutrient‐rich rivers and associated floodplains function as spawning and nursery grounds, and suggest that they function as source habitats for these species in the Amazon Basin. 相似文献
10.
Elasmobranch reproductive behavior has been inferred from freshly caught specimens, laboratory examinations of reproductive structures and function, or determined from direct observations of captive or free swimming wild animals. Several general behaviors have been described including seasonal sexual segregation, courtship and copulation. Courtship behavior was inferred for many species from the presence of scars and tooth cuts on the female's body, and noted in more detail from underwater observations. Copulation has been directly observed in captive settings for several species of elasmobranchs in large aquaria, and in the wild for three species of urolophids and for Triaenodon obesus and Ginglymostoma cirratum. A detailed case history of nurse shark reproductive behavior is presented that may be used as a template for future work on shark reproductive behavior of other species. Our studies, using diver identifiable tags and in situ behavioral observations, provide unprecedented information on social structure and mating behavior in this species. Since 1993, 115 G. cirratum, 45 adults and 70 juveniles have been tagged in the Dry Tortugas, Florida. Observations show that adult males visit the study site every year with three males dominant. Individual adult females visit the study area to mate in alternate years. Polygyny and polyandry are common. Future research on reproductive behavior of elasmobranchs should address questions on male access to females, sexual selection and dominance hierarchies. 相似文献