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41.
E. Filaire P. Duché G. Lac 《European journal of applied physiology and occupational physiology》1998,77(5):452-456
In a group of 20 elite female handball or volleyball players, an evaluation was made of the response to a 4-month training
period of cortisol, androstenedione and dehydroepiandrosterone in the saliva. At the beginning of the training programme (W1) and at the 7th (W7) and 16th weeks (W16), hormone concentrations were measured on awakening (8 a.m.; resting samples), and also before (t
0) and at the end (t
120) of a 2-h exercise session (simulated match) which took place at 6 p.m. The training programme increased the concentrations
of adrenal androgens in the saliva at rest (P<0.05) for both groups of subjects, with no change being noted in cortisol concentrations. In contrast, amongst the volleyball
players, stressful stimuli produced by an increase in the amount of training did not affect adrenocortical metabolism during
exercise. Indeed, a simulated volleyball match resulted in a decrease in salivary cortisol (P<0.05) and androgen concentrations (P<0.05) without regard for the week chosen for the test investigations. In contrast, a simulated handball match caused an increase
in cortisol concentrations at W1 only (P<0.05), with no change in the adrenal androgens concentration in any week of the training programme. The regulators of these
hormones during a period of exercise and during the course of a training programme would seem to be different.
Accepted: 30 October 1997 相似文献
42.
五唇兰雌配子体发育和胚胎发生的研究 总被引:13,自引:2,他引:11
五唇兰的胚珠倒生型,具薄珠心,两层珠被。胚囊发育为双孢子葱型,成熟胚囊8核。从传粉到受精约50d,正常双受精。胚具5-6细胞的胚柄,种子成熟时胚柄及胚乳核消失,成熟种子只具单层细胞的种皮和一个未分化的珠珠形胚。 相似文献
43.
短柄五加大,小孢子发生和雌,雄配子体发育的研究 总被引:6,自引:2,他引:4
短柄五加花药5枚,每个花药四个花粉囊。小孢子母细胞减数分裂时,胞质分裂为同时型,产生正四面体形的四分体。花药壁由表皮、药室内壁、中层和绒毡层四层细胞组成,其发育类型为双子叶型。腺质绒毡层,其细胞为二核。三细胞型花粉。子房5室,每室两个胚珠,上胚珠败育,下胚珠可育。下胚珠倒生,具单珠被,厚珠心。大孢子母细胞减数分裂形成线性排列的四个大孢子,雌配子体发育属蓼型。开花当天,花粉散开,雌配子体尚未成熟,处 相似文献
44.
Summary The postnatal development of formaldehyde induced fluorescence (FIF) was studied in the pituitary glands of female rats. The effects of 3,4-dihydroxyphenylalanine (L-dopa), D,L-5-hydroxytryptophan (DL-5-HTP) and dopamine (DA) treatments on the FIF were followed during the postnatal period.The appearance of specifically fluorescing monoamines into the cells of the pars intermedia occurred postnatally and the level of the adult fluorescence was reached at 4–5 weeks' age. The intensity of the fluorescence was independent on the density of the fluorescing nerves. Among the fluorescing nerves droplet fibres were regularly observed from the age of 3 weeks, which confirms the theory that these fibres are caused by toxic factors when the blood-brain barrier is not functioning.There was no change postnatally in the number of fluorescing cells in the pars distalis.The fluorescing innervation of the median eminence, developed most rapidly at the age of 1–3 weeks and the level of the adult fluorescence was reached at the age of 4–5 weeks.The first specifically fluorescing cells after L-dopa treatment were observed at 6 days age. A remarkable increase in the number of fluorescing cells was seen between 12 and 18 days. After DL-5-HTP treatment fluorescent cells were seen but at later stages. These observations suggest that the cells in the pituitary gland, which store amine-precursors and monoamines developmentally differ from the APUD-cells. The rapid increase of the fluorescing cells between 12 and 18 days and the simultaneous development of the fluorescing innervation of the median eminence suggest the following correlations: the development of dopaminergic innervation of the median eminence — the secretion of releasing hormones — the activity of PAS-positive cells (FSH, LH and TSH secretion) — the uptake of L-dopa and DL-5-HTP into the PAS-positive cells.Dopamine was not uptaken into the cells of pars distalis. The walls of the blood vessels began to show fluorescence suggesting a barrier mechanism, which prevents the DA-uptake into the PAS-positive cells.This work was supported by the Grant for Young Research Workers, University of Helsinki. 相似文献
45.
为了解濒危兰科植物小叶兜兰(Paphiopedilum barbigerum Tang et Wang)胚珠和雌配子体的发育过程,采用常规石蜡切片技术对其果实的生长动态进行了研究。结果表明,授粉后60~75 d的蒴果内种子数量迅速增加,到授粉后120 d时种子充满整个蒴果。授粉后40 d的胎座上分化形成多数由1层表皮细胞包被1列细胞的胚珠原基;授粉后60 d时位于胎座指状结构末端处紧靠表皮细胞下方的孢原细胞分化为大孢子母细胞。之后,大孢子母细胞经过减数分裂和有丝分裂最终形成成熟胚囊;授粉后135 d胚囊发育成熟,附着在胎座上的种子个体分化明显。小叶兜兰胚囊的发育类型为双孢子葱型,胚珠为倒生胚珠,薄珠心,单珠被,成熟胚囊为8核。这为小叶兜兰的生殖生物学及繁殖体系的建立提供理论依据。 相似文献
46.
Milena Niemiec Maciej G?ogowski Dobromira Tyc-Szczepaniak Marek Wierzchowski Lucyna K?pka 《Reports of Practical Oncology and Radiotherapy》2011,16(2):49-53
Background and aim
Long-term survival of lung cancer patients with brain metastases (BM) is very rare. Our aim is to report the characteristics of patients who survived for at least three years after a BM diagnosis.Materials and methods
Nineteen lung cancer patients who had survived ≥3 years after a BM diagnosis were identified in our database. Seven (37%) had undergone whole-brain radiotherapy (WBRT) only, five (26%) BM surgery + WBRT, three (16%) BM surgery + WBRT + BM radiosurgery, and four (21%) no WBRT (one, surgery; one, radiosurgery; two, BM surgery + radiosurgery). Their characteristics were compared with historical data for 322 lung cancer patients with BM (control group, CG), who had received WBRT between 1986 and 1997.Results
Median survival from BM in long survivors group was 73 months (in CG – 4 months). Characteristics comparison: median age 55 vs. 58 (CG), p = 0.16; female sex 68% vs. 28% (CG), p = 0.003; RTOG/RPA class 1 – 75% vs. 13% (CG), p = 0.00001; adenocarcinoma histology 84% vs. 24% (CG), p < 0.00001; control of primary tumor 95% vs. 27% (CG), p < 0.00001; extracranial metastases 0 vs. 26% (CG), p = 0.01; single BM 63% vs. 9% (CG), p = 0.00001; surgery of BM 53% vs. 14% (CG), p = 0.00001.Conclusions
Beside prognostic factors already recognized as favorable in patients with BM, the adenocarcinoma histology and female sex were prevalent in long-term survivors of BM from lung cancer. 相似文献47.
Takahata Y Koyama N Ichino S Miyamoto N Nakamichi M Soma T 《Primates; journal of primatology》2008,49(2):135-138
We used data from a 13-year field study of wild ringtailed lemurs to analyze the relationship between female rank and reproductive
parameters. In medium and small groups there were no significant differences in birth rate, infant mortality rate, and the
number of surviving infants between the female rank categories. On the other hand, in large sized groups low-ranked females
had a smaller number of surviving infants than middle-ranked females. This suggests that in large sized groups, within-group
competition lowered the values of reproductive parameters of low-ranked females. On the other hand, high and low-ranked females
of small sized groups tended to have a smaller number of surviving infants than high-ranked females of medium sized groups
and middle-ranked females of large sized groups. Between-group competition should lower the values of their reproductive parameters.
In sum, these results fit the expectation from Wrangham’s (1980) inter group feeding competition model. 相似文献
48.
De Silva V Bostwick D Burns KL Oldham CD Skryabina A Sullards MC Wu D Zhang Y May SW Pullman GS 《Plant cell reports》2008,27(4):633-646
Loblolly pine (LP, Pinus taeda) is the primary commercial species in southern forests of the US. Somatic embryogenesis (SE) is an effective technique to
implement clonal tree production of high-value genotypes from breeding and genetic engineering programs. Unlike angiosperm
embryos with attached cotyledons as seed storage organs, the diploid conifer embryo is surrounded by the unattached haploid
female gametophyte (FG). The FG is not present in culture. This presents a dilemma if the FG produces necessary or regulatory
compounds for embryo growth, since in culture these important compounds would be missing and would have to be added as supplements.
We report here the direct evidence that extracts from early-stage FG indeed stimulate early-stage somatic embryo (SME) growth
and multiplication, whereas extracts from late-stage FG inhibit early-stage SME growth. Furthermore, we have now isolated
this stimulatory substance from early-stage FG tissue, and identified this substance as citric acid on the basis of NMR and
mass spectrometry. We then demonstrated that topical application of citric acid to SMEs stimulates embryo colony growth at
P = 0.05. Moreover, we find that there is a good correlation between the amount of citric acid isolated from FG tissue (65
nmoles per stage 2–3 FG) and the amount of citric acid that stimulates colony growth (25–50 nmoles) when applied topically
to SMEs. This approach of isolating and characterizing a molecule from plant tissue, and investigating its role on SE processes
can provide valuable information leading to further applications of these molecules to improve LP SE protocols. 相似文献
49.
Barbara Hefti-Gautschi Monika Pfunder Lukas Jenni Verena Keller Hans Ellegren 《Conservation Genetics》2009,10(1):87-99
The conservation status of small breeding areas of the Goosander (Mergus merganser merganser) in Central Europe is unclear. Geographic isolation of these areas suggests restricted gene flow to and from large North-European
populations. On the other hand, migrating Goosanders from northern Europe join the Central European breeding population for
wintering. To evaluate the conservation status of the small breeding areas we assessed the genetic structure of M. merganser populations in Europe by examining two nuclear marker systems (microsatellites and Single Nucleotide Polymorphisms, SNP)
and mitochondrial (mtDNA) control region sequence variation for Goosanders in 11 sampling areas representing three of five
distinct breeding areas and two subspecies (M. m. merganser and M. m. americanus). Overall population differentiation estimates including both subspecies were high, both based on mtDNA () and nuclear markers (θ
ST = 0.219; 95% CI 0.088–0.398, SNP and microsatellites combined). Within Europe, mtDNA revealed a strong overall () and significant pairwise population differentiation between almost all comparisons. In contrast, both nuclear marker systems
combined revealed only a small overall genetic differentiation (θ
ST = 0.022; 95% CI 0.003–0.041). The strong genetic differentiation based on female-inherited mtDNA but not on biparentally
inherited nuclear markers can be explained by sex-biased dispersal and strong female philopatry. Therefore, small breeding
areas in Europe are endangered despite large male-mediated gene-flow, because when these populations decline, only males—but
due to strong philopatry not females—can be efficiently supplemented by migration from the large North European populations.
We therefore propose to manage the small breeding areas independently and to strengthen conservation efforts for this species
in Central Europe. 相似文献
50.
Conservation programs that deal with small or declining populations often aim at a rapid increase of population size to above-critical levels in order to avoid the negative effects of demographic stochasticity and genetic problems like inbreeding depression, fixation of deleterious alleles, or a general loss of genetic variability and hence of evolutionary potential. In some situations, population growth is determined by the number of females available for reproduction, and manipulation of family sex ratios towards more daughters has beneficial effects. If sex determination is predominantly genetic but environmentally reversible, as is the case in many amphibia, reptiles, and fish, Trojan sex chromosomes could be introduced into populations in order to change sex ratios towards more females. We analyse the possible consequences for the introduction of XX-males (XX individuals that have been changed to phenotypic males in a XY/XX sex determination system) and ZW males, WW males, or WW females (in a ZZ/ZW sex determination system). We find that the introduction of WW individuals can be most effective for an increase of population growth, especially if the induced sex change has little or no effect on viability. 相似文献