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141.
Yerushalmi Y Bhargava K Gilon C Pener MP 《Insect biochemistry and molecular biology》2002,32(8):909-917
The dark-colour-inducing effect of several peptides in comparison to that of the dark-colour-inducing neurohormone (DCIN, [His(7)]-corazonin) of locusts was investigated by a bioassay based on nymphs of a DCIN-deficient albino mutant of Locusta migratoria. The study was aimed at elucidating the active part of the DCIN and to explore the contribution of its amino acids to the activity. Graded doses of all peptides were injected in oil. [Arg(7)]-corazonin and DCIN were equally effective. Certain arthropod neuropeptides having the -SXGW- partial sequence (a part of the DCIN and of [Arg(7)]-corazonin; X=His and X=Arg, respectively) yielded the following findings: Scg-AKH-II (adipokinetic hormone II of Schistocerca gregaria X=Thr), Grb-AKH ( adipokinetic hormone of Gryllus bimaculatus X=Thr) and RPCH (red pigment concentrating hormone of crustaceans X=Pro) evoked a moderate darkening response, but Lom-AKH-II (adipokinetic hormone II of L. migratoria X=Ala) was ineffective. Step by step shortening of the sequence of the DCIN at the N-terminal, from pGlu-3-11DCIN to pGlu-9-11DCIN, resulted in a decreasing activity, but even pGlu-9-11DCIN induced a weak response with high doses. Shortening of the DCIN from the C-terminal revealed a moderate activity of 1-7DCIN-NH(2) and a weak activity of 1-5DCIN-NH(2). An octadecapeptide which induces dark colour in moth larvae, having the pentamer FTPRL-NH(2) at its C-terminal, evoked no darkening in the albino locusts. We conclude that although the -SXGW- partial sequence has some role in induction of darkening, for obtaining maximal effect the whole sequence of the DCIN (or of [Arg(7)]-corazonin) is necessary. 相似文献
142.
Comparative effect of water, heat and light stresses on photosynthetic reactions in Sorghum bicolor(L.) Moench 总被引:2,自引:0,他引:2
Five varieties of Sorghum bicolor (L.) Moench.,
differing in their drought tolerance under field conditions have been used
to study the effect of individual components of drought stress, namely high
light intensity stress, heat stress and water stress, on their
photosynthetic performance. Chlorophyll content, chlorophyll fluorescence,
ribulose-1,5-bisphosphate carboxylase (Rubisco, EC 4.1.1.39) content,
phosphoenolpyruvate carboxylase (PEPcase, EC 4.1.1.31) activity and
photo-synthetic oxygen evolution were used as key parameters to assess
photosynthetic performance. The results indicated that photochemical
efficiency of photosystem II (PSII) was severely reduced by all three
stress components, whereas PEPcase activity was more specifically reduced
by water stress. Degradation of Rubisco and chlorophyll loss occurred under
high light and water stress conditions. Of the four drought-tolerant
varieties, E 36-1 showed higher PEPcase activity, Rubisco content and
photochemical efficiency of PSII, and was able to sustain a higher maximal
rate of photosynthetic oxygen evolution under each stress condition as
compared to the other varieties. A high stability to stress-induced damage,
or acclimation of photosynthesis to the individual components of drought
stress may contribute to the high yields of E 36-1 under drought
conditions. In the E 36-1 variety markedly higher levels of the
chloroplastic chaperonin 60 (cpn 60) were observed under all stress
conditions than in the susceptible variety CSV 5.Key words: Chlorophyll
fluorescence, drought stress, oxygen evolution, phosphoenopyruvate
carboxylase, Sorghum.
相似文献
143.
Epidermal growth factor (EGF) at nanomolar concentrations stimulated DNA synthesis in confluent, serum-starved cultures of calf aorta and human uterine smooth muscle cells. Stimulation of DNA synthesis in lens epithelial cells was studied for comparison. L and D-ascorbic acid potentiated the effect of serum and EGF on DNA synthesis in calf aorta cells. In contrast L-ascorbic acid had minimal potentiating effect with serum and no effect with EGF present along with serum on DNA synthesis in human uterine smooth muscle and rabbit lens epithelial cells. EGF and ascorbic acid increased cell number when added to stationary phase cultures. Specific binding of 125I-labelled EGF to smooth muscle cells was demonstrated. Receptor concentration in calf-aorta smooth muscle cells was higher in dense cultures compared to sparse cultures. The time course of binding and dissociation of 125I-labelled EGF was similar in "dense" and "sparse" cultures. Human uterine smooth muscle cells in culture exhibited a finite lifespan. There was no stimulation of DNA synthesis in response to serum and EGF in cells of high population doubling level (PDL); although 125I-labeled EGF binding was higher in old cells (high PDL) compared to young cells (low PDL). This increase in binding was shown to be due to changes in the concentration of receptors without changes in their affinity for EGF. 相似文献
144.
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146.
Water quality samples were obtained monthly or bimonthly 17 times from May 1974 to May 1975 at three stations in Delaware
Bay. In addition, two 12-hour cruises were also conducted at one station in February and April 1975. Surface and bottom water
samples were taken. Measurements and analyses included temperature, salinity, dissolved oxygen, silicate, nitrate and nitrite,
orthophosphate, ammonia, chlorophylls a, b, and c, phaeopigments, and carotenoids.
The annual pattern of temperature was typical of an estuary in the mid-Atlantic Bight. Salinity and dissolved oxygen ranged
from 22.9 to 29.7‰ and from 4.53 to 8.53 ml/l, respectively. Nutrient and pigment values showed seasonal peaks. Silicate (30.3
μg-at/1) and orthosphate (1.59 μg-at/1) were highest in September. Highest concentrations of ammonia were commonly measured
in July (6.80 μg-at/1) and September (5.13 μg-at/1), and peak concentrations of nitrate and nitrite were recorded in January
(24.27 μg-at/l), February (18.2 μg-at/1), and May (16.37 μg-at/1). Peak concentrations of chlorophyll a were measured in August (17.2 μg-at/1), October (15.70 μg-at/1), and March (15.33 μg-at/1). In general, the annual pattern
for chlorophylls b and c were similar to chlorophyll a. Comparison with other estuaries and bays (Narrangansett Bay, Long Island Sound, Raritan Bay, and Chesapeake Bay) indicated
that concentrations of nutrients and pigments in Delaware Bay were generally similar in magnitude and seasonality, These are
the first set of seasonal water quality data for lower Delaware Bay. 相似文献
147.
C. Birek J. E. Aubin U. Bhargava D. M. Brunette A. H. Melcher 《In vitro cellular & developmental biology. Plant》1982,18(4):382-392
Summary Multicellular, cystic structures, termed domes, have been described previously in epithelia cultured from various tissues
that have a known transport or secretory function in vivo and in vitro. We report for the first time dome formation in cells
cultured from “covering” and “rest” epithelia of oral tissues: porcine gingival and alveolar mucosa epithelium and epithelial
rests of Malassez. As demonstrated by light- and electron microscopy, the morphology of the domes varied with the location
of their lumen and the number of cells or cell layers involved in their structure. Sequential observations using phase contrast
microscopy and time lapse cinematography of living cultures showed that the domes were dynamic structures with expansion-collapse
cycles of between 30 min and 17 h duration. Dome formation in oral epithelia was stimulated by dibutyryl cyclic AMP (dbcAMP,
10−3 to 10−6
M) and abolished by ouabain (10−10
M), an inhibitor of sodium transport.
The morphological features and the dynamic nature of domes found in oral epithelia, and their dbcAMP and ouabain responsiveness
are similar to those demonstrated previously in several other epithelia that have a known transport function in vivo and in
vitro. Such fluid transport is not thought to be a property of oral epithelia in vivo. Our data, however, suggest a similar
function of these epithelia cultured in vitro, and perhaps in pathological cyst formation in vivo. 相似文献
148.
Aberrant frenum attachment would cause plaque accumulation and malalignment of teeth. It can be managed by frenotomy or frenectomy methods, through a conventional surgical technique or laser technique. Therefore, it is of interest to compare frenectomy healing surgical and laser techniques. Data from 51 outpatients and post-operative healing of frenectomy was assessed by Landry’s healing score index using 3 weeks postoperative photographs followed by statistical analysis. Based on the healing score index, the laser technique showed better outcomes than the surgical technique. Moreover, the association between the management of high frenal attachment and the healing score index was found to be statistically significant. 相似文献
149.
150.