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261.
Adler I Walter LS Lowman PD Glass BP French BM Philpotts JA Heinrich KJ Goldstein JI 《Science (New York, N.Y.)》1970,167(3918):590-592
Plagioclase feldspar, clinopyroxene, and ilmenite in a polished thin section of a type A crystalline rock were analyzed. The clinopyroxene grains are compositionally variable, and both high Ca and low Ca phases are present. The plagioclase is compositionally homogeneous. The ilmenite is chemically homogeneous except for occasional, small areas of high local chromium concentration. Accessory minerals are: apatite (containing Cl, F, Y, and Ce), troilite, and metallic iron. Glassy spherules from the lunar soil are for the most part similar in composition to the crystalline rocks; however, some appear to have been monomineralic. The crystalline rock has apparently formed by relatively rapid cooling of a silicate melt under conditions of low oxygen partial pressure. Many components of the soil appear to have formed by meteoritic impact. 相似文献
262.
Marihuana: standardized smoke administration and dose effect curves on heart rate in humans 总被引:2,自引:0,他引:2
A spirometer was used to deliver marihuana and placebo smoke to human subjects. This procedure produced linear dose-effect curves on heart rate and replicable dose effects in individual subjects. No differences were observed between experienced and inexperienced smokers in responsiveness to heart rate increases produced by marihuana. 相似文献
263.
Helical structures of ESCRT-III are disassembled by VPS4 总被引:1,自引:0,他引:1
Lata S Schoehn G Jain A Pires R Piehler J Gottlinger HG Weissenhorn W 《Science (New York, N.Y.)》2008,321(5894):1354-1357
During intracellular membrane trafficking and remodeling, protein complexes known as the ESCRTs (endosomal sorting complexes required for transport) interact with membranes and are required for budding processes directed away from the cytosol, including the budding of intralumenal vesicles to form multivesicular bodies; for the budding of some enveloped viruses; and for daughter cell scission in cytokinesis. We found that the ESCRT-III proteins CHMP2A and CHMP3 (charged multivesicular body proteins 2A and 3) could assemble in vitro into helical tubular structures that expose their membrane interaction sites on the outside of the tubule, whereas the AAA-type adenosine triphosphatase VPS4 could bind on the inside of the tubule and disassemble the tubes upon adenosine triphosphate hydrolysis. CHMP2A and CHMP3 copolymerized in solution, and their membrane targeting was cooperatively enhanced on planar lipid bilayers. Such helical CHMP structures could thus assemble within the neck of an inwardly budding vesicle, catalyzing late steps in budding under the control of VPS4. 相似文献
264.
Heinrich B 《Science (New York, N.Y.)》1972,175(4018):185-187
Bombus vagans forages for nectar at 5 degrees C in shade and at 31 degrees C in sunshine. The production of heat while the bumblebee is on flowers, at ambient temperatures below 24 degrees C, helps to maintain a thoracic temperature that is near the minimum for flight between flowers. However, at ambient temperatures above 24 degrees C the thoracic temperature is no longer regulated at 32 degrees to 33 degrees C and rises. 相似文献
265.
Heinrich B 《Science (New York, N.Y.)》1970,168(3931):580-582
The sphinx moth, Manduca sexta, maintains its thoracic temperature within a degree of 42 degrees C while in free flight over a range of air temperatures from about 17 degrees to 32 degrees C. Tying off the dorsal vessel abolishes temperature control. Moths with tied off vessels overheat and then stop flying at air temperatures of about 23 degrees C. However, flight at this temperature is possible when the thoracic scales are removed. The mechanism of temperature control involves transfer of the heat produced in the thorax to the blood pumped from the dorsal vessel, and the subsequent dissipation of this heat when the blood returns to the relatively cool abdomen. 相似文献
266.
Simeon Springmann Robert Rogers Heinrich Spiecker 《Forest Ecology and Management》2011,261(3):764-769
Producing high value veneer wood requires that the tree bole be branch-free. This can be accomplished by natural or artificial pruning. Since wild cherry does not self prune well, pruning artificially is the only practical option. The study analysed the effect of conventional whorl-wise pruning and selective pruning, on height growth, diameter growth and secondary shoot development of wild cherry. Four pruning treatments were applied on cherry trees in summer 2007, one group of cherries was left unpruned to serve as a control: treatment C1 (upper 5 whorls left), C2 (upper 3 whorls left), S1 (removal of branches larger than 3 cm or with an angle to the stem < 40°), S2 (removal of branches larger than 2 cm or with an angle to the stem < 40°), N (unpruned). Data showed that height growth was not affected by pruning. In contrast, diameter growth at breast height of the C2 pruned cherry was reduced by approximately 5% (SE = 2.7%) in the year of pruning (trees were pruned in July). This pruning treatment produced significant (p = 0.028) nine percent less diameter growth than the control in the second year following pruning. The diameter increment of the C1 pruned trees with five whorls left after pruning and the selective pruned cherries were only about 4% (SE = 4.0%) smaller than the control after two years. This loss was statistically not significant. Analyses showed that on selective pruned trees the survival rate of secondary shoots was significantly reduced compared to those on whorl-wise pruned trees. Significant differences in the size of the secondary shoots were only found between the C1 and S1 (p < 0.05) pruned trees. We did not find differences in the total number of secondary shoots per tree among pruning treatments. Solely from a tree growth perspective, the moderate whorl-wise pruning treatment C1 and the selective prunings were equally effective in minimizing the reduction of diameter growth and are recommended in practice. However it was found that the survival of secondary shoots was reduced on selective pruned trees although the amount of pruning work needed in selective pruning was slightly greater than conventional moderate pruning. 相似文献
267.
Intercultural studies about the methods of use and perceptions of traditional remedies in Europe are strategically important in understanding how pharmaceutical means in our multicultural modern societies are differently accepted by diverse ethnic groups. In this survey, we analysed the biological means traditionally used in the ethnomedicine of three Arb?resh? (ethnic Albanians) communities in the Vulture area (northern Lucania, southern Italy). The majority of remedies are represented by plants belonging to 54 botanical taxa. A few of the recorded species have a traditional therapeutic use that has never previously been reported in southern Italy. Other means-especially used in the past-are comprised of mineral, animal and industrial derived materials. In specific cases, some of these materials and even plants are neither applied externally or internally, but are instead utilised as symbolic ritual objects in spiritual healing ceremonies. Ethnopharmacological and anthropological considerations about these usages are discussed. 相似文献
268.
269.
Liu Y Walker F Hoeglinger B Buchenauer H 《Journal of agricultural and food chemistry》2005,53(17):6864-6869
A trichloroacetic acid treatment at 140 degrees C for 40 min was successfully established as a suitable solvolysis procedure for the recovery of bound deoxynivalenol or its derivatives in Fusarium-infected plants. Deoxynivalenol itself was not decomposed in the procedure. The derivative 15-acetyl-deoxynivalenol was chosen as a model compound for setting free deoxynivalenol in an acid-catalyzed deesterification reaction, developing the method. This is the first report using a trichloroacetic acid solvolysis procedure as a sample incubation step to free bound deoxynivalenol and determine free from bound deoxynivalenol in the sample. Between 13 and 63% of the total deoxynivalenol consisted of nonextractable deoxynivalenol. Deoxynivalenol contents in grain of the susceptible cultivar "Agent" infected with Fusarium spp. were 12-24 times higher when compared to those for the corresponding moderately resistant cultivar "Petrus". The highest deoxynivalenol amounts were determined in grain infected with Fusarium spp. as well as simultaneously infected with BYDV. This solvolysis procedure may be of importance for distinguishing between resistant and susceptible plants and their ability to immobilize (bound) mycotoxins as a plant defense mechanism. 相似文献
270.
Quantitative estimation of the mineralogical composition from silt-fractions of soils on the basis of the chemical analysis and by application of the Karl-Fischer-titration. II. Results obtained with soils from glacial sand, boulder marl and loess The contents of micas and feldspars were quantified in the silt-fractions from horizons of a podsolic brown earth developed on glacial sand and of lessives on loess as well as on boulder marl by using a method that has been described in detail in part I. Three components each of micas and of feldspars, namely muscovite (Ms), phlogopite (Phl), annite (Ann), orthoclase (Or), albite (Ab) and anorthite (An) were determined. The silt fractions of the three investigated soils are similar in their mineralogical composition. Feldspars are composed of equally high amounts of Or and Ab. Micas are dominated by the Ms-component. Apparently the mica content of the silt fractions is reduced during soil development, whereas no significant changes can be found for feldspars. The loss of micas is responsible for the decreasing potassium content of the silt fractions. 相似文献