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51.
The Environmental Exposure Unit (EEU) is a 924 m3 facility (Kingston General Hospital, Ontario) in which uniform concentrations of various pollens in HEPA-filtered air at
known rates of laminar airflow can be maintained. This facility provided a unique opportunity to compare several air samplers
without the environmental variation inherent in outdoor comparisons. The purpose of this study was to conduct a quantitative
comparison of pollen measurements using the Rotorod, Burkard™ Personal Volumetric Air Sampler, Air-O-Cell™ and a 37 mm open-faced
filter cassette with a microporous filter in the EEU. Pollen samples were taken during clinical trials being conducted in
the Unit. Raw pollen counts/m3 obtained using the different methods were corrected using published particle collection efficiencies for the particle size
(∼
∼20 μm) and airflow. Data were analyzed by ANOVA/Tukey HSD. No statistically significant differences were found between pollen
concentrations determined by Rotorod, Air-O-Cell and filter cassette. Pollen levels determined by the Burkard were up to 2
times higher than the other sampling methods. Relative standard deviations were similar for the Rotorod, Burkard, and filter
cassette and higher for the Air-O-Cell. This study demonstrated that, under our conditions, the Rotorod sampler provides consistent
and reliable measurements of ragweed pollen concentrations. 相似文献
52.
Data on pollen and pistil traits from 14 Argentinean Nyctaginaceae species with starch or lipids as pollen reserves are presented.
We expect differences in the traits between these two groups of species, but the same pattern within each group for (a) the
relationship between pollen size and pistil length assuming that pollen tube length is predetermined by provisions in the
pollen independently of the pollen reserve type, and for (b) a trade-off between size and number because available resources
for male function are not unlimited. In particular we expect that (a) species with longer pistils will have larger pollen
grains, (b) pollen grain size and the number of pollen grains per flower will be negatively correlated. Significant differences
in the mean pollen number per flower and mean pollen size were observed between species with different pollen reserve type
but not for pistil length. Then, correlation analyses were performed for species with starchy pollen or with pollen with lipids
separately. Pollen size - pistil length correlation was positive and significant for species with starchy pollen but not for
species with pollen with lipids. On the other hand, pollen size - number correlation was not significant for both starchy
and oil-rich species. Results suggest that pollen reserve type would be a relevant factor that constraint pollen size in species
of Nyctaginaceae, and that this pollen trait should be considered when studying pollen-pistil relationships, mainly between
species of those families with mixed pollen reserves. 相似文献
53.
珍珠菜属植物的花粉形态及其系统进化学意义 总被引:7,自引:0,他引:7
利用光学显微镜、扫描电镜和透射电镜对20 种珍珠菜属植物的花粉形态结构进行了详细研究。根据花粉的大小、形状、表面纹饰和外壁构造等特征可划分为四大类型,即细梗香草型、白花过路黄型、过路黄型和黑腺珍珠菜型。对它们可能的进化水平进行了分析,并结合形态学、细胞学等资料进一步探讨了珍珠菜属各亚属间的系统演化关系。 相似文献
54.
The effect of different external factors on pollen germination and pollen tube growth is well documented for several species. On the other hand the consequences of these factors on the division of the generative nucleus and the formation of callose plugs are less known. In this study we report the effect of medium pH, 2-[N-morpholino]ethanesulfonic acid (MES) buffer, sucrose concentration, partial substitution of sucrose by polyethyleneglycol (PEG) 6000, arginine (Arg), and pollen density on the following parameters: pollen germination, pollen tube length, division of the generative nucleus, and the formation of callose plugs. We also studied the different developmental processes in relation to time. The optimal pH for all parameters tested was 6.7. In particular, the division of the generative nucleus and callose plug deposition were inhibited at lower pH values. MES buffer had a toxic effect; both pollen germination and pollen tube length were lowered. MES buffer also influenced migration of the male germ unit (MGU), the second mitotic division, and the formation of callose plugs. A sucrose concentration of 10% was optimal for pollen germination, pollen tube growth rate and final pollen tube length, as well as for division of the generative nucleus and the production of callose plugs. Partial substitution of sucrose by PEG 6000 had no influence on pollen germination and pollen tube length. However, in these pollen tubes the MGU often did not migrate and no callose plugs were observed. Pollen tube growth was independent of the migration of the MGU and the deposition of callose plugs. In previous experiments Arg proved to be positive for the division of the generative nucleus in pollen tubes cultured in vitro. Here, we found that more pollen tubes had callose plugs and more callose plugs per pollen tube were produced on medium with Arg. After the MGU migrated into the pollen tube (1 h after cultivation), callose plugs were deposited (3 h). After 8 h the first sperm cells were produced. The MGU moved away from the active pollen tube tip until the second pollen mitosis occurred, thereafter the distance from the MGU to the pollen tube tip diminished. Callose plug deposition never started prior to MGU migration into the pollen tube. Pollen tubes without a MGU also lack callose plugs (±30% of the total number of pollen tubes). Furthermore, we found a correlation between the occurrence of sperm cells in pollen tubes and the synthesis of callose plugs. 相似文献
55.
The ability to extract pollen contents may be related to the extent to which animals use this item as a regular part of their diet. In spite of the broad diversity of taxa that feed on pollen, comparative studies to test this hypothesis are scarce. We compared the extraction efficiency of pollen grains of Blue Mahoe (Talipariti elatum) by Antillean nectar bats (Brachyphylla nana) and Jamaican fruit bats (Artibeus jamaicensis). Antillean nectar bats extracted the contents of a higher percentage of pollen grains than Jamaican fruit bats, even though processing time in the gut was lower in the nectarivorous bats. Pollen extraction efficiency increased with time spent in the gut in each species. The gastrointestinal tract in both species resembled the functioning of a continuous stirred-tank reactor (CSTR) equivalent to the stomach, in series with a plug-flow reactor (PFR) equivalent to the intestine with varying degrees of longitudinal mixing. Accordingly, pollen grains flowed continuously out of the stomach and moved out through the intestine where they were mixed longitudinally. Our results support previous findings of higher extraction efficiencies in nectarivorous bats than their frugivorous relatives, and suggest that these differences may be the result of differences in the level of activity of the enzymes responsible for pollen wall degradation. Identification of enzymatic mechanisms of pollen degradation would allow a direct test of this hypothesis. 相似文献
56.
DingWU HongWANG De-ZhuLI StephenBLACKMORE 《植物学报(英文版)》2005,47(1):2-12
The pollen morphology of 28 species of Parnassia L. was investigated with light microscopy and scanning electron microscopy (SEM). The shape of pollen grains in this genus varies from subspheroidal to prolate in equatorial view and is three-lobed circular in the polar view. Pollen grains are usually radially symmetrical, isopolar, tricolporate or syntricolporate, with reticulate sculpture. The pollen characteristics among species are fairly similar to each other. Morphological information regarding the pollen grains shows that Parnassia is a natural genus. Based on exine ornamentation observed under SEM, three types of pollen grains were recognized: (i) type I, with foveolate-reticulate sculpture; (ii) type II, with a finely reticulate sculpture; and (iii) type III, with a coarsely reticulate sculpture. Most sections of this genus have one type of sculpture of pollen morphology, but Sect. Nectarotrilobos has three types of sculpture and Sect.Saxifragastrum has two types of sculpture. All three types of sculpture can be found in Southwest China,with species with the longest (Parnassia delavayi Franch.) and shortest (Parnassiafaberi Oliv.) colpi,implying that Southwest China is the center of diversification of the genus. 相似文献
57.
Na-Na LIN Hong WANG De-Zhu LI Stephen BLACKMORE 《植物学报(英文版)》2005,47(9):1036-1046
The pollen morphology of 28 species and one variety representing eight genera of the subtribe Mutisiinae Less. sensu Bremer (Compositae) was investigated by scanning electron microscopy (SEM) and light microscopy. The pollen grains are usually radically symmetrical, isopolar, and tricolporate. The shape varies from spheroidal to subprolate in equatorial view and is three-lobed circular in polar view. Based on exine sculpturing observed under SEM, the pollen grains can be divided into three types: (i) type Ⅰ, with macrogranulate sculpture; (ii) type Ⅱ, with a finely granulate sculpture; and (iii) type Ⅲ with spiny sculpture. The palynological data showed that the Macroclinidium Maxim. was remarkably distinguished from those of the other seven genera. The variation of pollen characteristics within the Mutisiinae in Asia is little at species level, but it proves some useful information for studying the relationships among genera and it has an important significance in further understanding the evolutionary history of Mutisiinae. 相似文献
58.
水稻籼粳亚种间杂种低温花粉不育的QTL分析 总被引:4,自引:0,他引:4
为探明籼粳杂种低温花粉不育的遗传基础,以籼稻品种3037和粳型广亲和品种02428的F2分离群体进行了低温花粉不育的遗传分析。推迟播种后,F2群体各单株孕穗期的日平均温度为21~23℃,调查了F2群体各单株的花粉育性。利用108对SSR引物构建了包含157个F2单株,覆盖12条染色体的分子标记连锁图谱。该连锁图的总长度为1857.8cM,标记间平均距离为16.26cM,标记较均匀地分布在12条染色体上。采用区间作图法对F2群体花粉不育进行QTL分析,共检测到2个低温花粉不育QTLS,即qLTSPS2和qLTSPS5,分别位于第2、5染色体,其加性效应分别为0.021、0.045,显性效应分别为-0.246、-0.251,显性度分别为11.7和4.8,具有超显性效应.超显性是QTL作用的主要方式,这2个位点杂合基因型在低温环境下具有降低花粉育性的作用,分别解释表型变异的15.6%、11.9%。另外,两因素的方差分析表明这两个QTL之间不存在互作。 相似文献
59.
Considerable knowledge exists about the effect of aluminium (Al) on root vitality, but whether elevated levels of Al affect
soil microorganisms is largely unknown. We thus compared soils from Al-treated and control plots of a field experiment with
respect to microbial and chemical parameters, as well as root growth and vitality. The field experiment was established in
a 50-year-old Norway spruce (Picea abies L.) stand where no Al or low concentrations of Al had been added every 7–10 days during the growth season for 7 years. Analysis
of soil solutions collected using zero tension lysimeters and porous suction cups showed that Al treatment lead to increased
concentrations of Al, Ca and Mg and lower pH and [Ca + Mg + K/Al] molar ratio. Corresponding soil analyses showed that soil
pH remained unaffected (pH 3.8), that exchangeable Al increased, while exchangeable Ca and Mg decreased due to the Al treatment.
Root in-growth into cores placed in the upper 20 cm of the soil during three growth seasons was not affected by Al additions,
neither was nutrient concentration or mortality of these roots. The biomass of some taxonomic groups of soil microorganisms,
analyzed using specific membrane components (phospholipid fatty acids; PLFAs), was clearly affected by the imposed Al treatment,
both in the organic soil horizon and in the underlying mineral soil. Microbial community structure in both horizons was also
clearly modified by the Al treatment. Shifts in PLFA trans/cis ratios indicative of short term physiological stress were not observed. Yet, aluminium stress was indicated both by changes
in community structure and in ratios of single PLFAs for treated/untreated plots. Thus, soil microorganisms were more sensitive
indicators of subtle chemical changes in soil than chemical composition and vitality of roots. 相似文献
60.
María-José Coronado Götz Hensel Sylvia Broeders Ingrid Otto Jochen Kumlehn 《Acta Physiologiae Plantarum》2005,27(4):591-599
Barley transformation mediated by Agrobacterium tumefaciens is routinely performed in a number of laboratories. However, elimination of selectable marker genes and formation of plants
homozygous for the transgene via conventional segregation is laborious and time-consuming. Here we suggest a concept that
includes the production of primary transgenic plants via infection of immature embryos with A. tumefaciens followed by androgenetic generation of a segregating population of entirely homozygous plants. Selectable marker-free, truebreeding
plants carrying a single-opy transgene integrant may thus be efficiently and rapidly obtained. However, amenability to Agrobacterium-mediated transformation as well as androgenetic potential is genotype-dependent. Efficient genetic transformation by infection
of immature embryos is so far confined to the spring type cultivar ‘Golden Promise’ which, however, turned out to be recalcitrant
in pollen embryogenesis. To facilitate androgenetic generation of homozygous segregants from primary transformants, we have
established a method for embryogenic pollen culture in cv. Golden Promise that includes conventional cold-treatment and subsequent
preculture of immature pollen under starvation conditions prior to transfer to complete nutrient medium. Further we show that
conditioning of the pollen culture medium by co-culture of immature wheat pistils as well as addition of pistil-preconditioned
medium considerably support androgenetic development. Employment of the established method using immature pollen of primary
transgenic plants demonstrates that selectable marker-free, true-breeding transgenic progeny can be rapidly obtained pursuing
the concept proposed. The protocol presented will be useful in functional genomics as well as in molecular breeding approaches. 相似文献