全文获取类型
收费全文 | 144篇 |
免费 | 12篇 |
出版年
2023年 | 1篇 |
2022年 | 3篇 |
2021年 | 3篇 |
2020年 | 5篇 |
2019年 | 5篇 |
2018年 | 2篇 |
2017年 | 5篇 |
2016年 | 4篇 |
2015年 | 3篇 |
2014年 | 3篇 |
2013年 | 8篇 |
2012年 | 11篇 |
2011年 | 11篇 |
2010年 | 5篇 |
2009年 | 7篇 |
2008年 | 12篇 |
2007年 | 10篇 |
2006年 | 7篇 |
2005年 | 7篇 |
2004年 | 1篇 |
2003年 | 3篇 |
2001年 | 3篇 |
2000年 | 1篇 |
1999年 | 2篇 |
1997年 | 1篇 |
1994年 | 2篇 |
1992年 | 1篇 |
1991年 | 1篇 |
1990年 | 1篇 |
1988年 | 1篇 |
1987年 | 1篇 |
1986年 | 1篇 |
1983年 | 7篇 |
1980年 | 1篇 |
1979年 | 2篇 |
1977年 | 1篇 |
1976年 | 1篇 |
1974年 | 3篇 |
1973年 | 2篇 |
1972年 | 2篇 |
1971年 | 3篇 |
1968年 | 1篇 |
1967年 | 2篇 |
排序方式: 共有156条查询结果,搜索用时 125 毫秒
131.
Changes in absorption characteristics and in Hill activity werestudied during ageing of isolated chloroplasts in the dark andlight. Ageing of chloroplasts brings about significant reductionin the peak absorption in the blue and red bands and resultsin a blue shift in the red band. Incubation of chloroplastsin the dark prevented the early appearance of a light-inducedblue shift at pH 7 and pH 8 but not at pH 6 of the storage media.Addition of BSA or DTT to chloroplast suspensions of pH 6 andpH 7 significantly delayed the blue shift both in the lightand dark, but the chemicals had no effect at pH 8. Ageing-induced loss in DCPIP reduction is restored considerablyby the addition of exogenous electron donors such as DPC orMn2+, which suggests loss of the oxygen evolution system. Mn2+loses its ability to donate electrons for DCPIP photoreductionduring ageing faster than DPC. This indicates that there aretwo sites between water and the PS II reaction centre for theentry of electrons from these two donors and that ageing causessequential loss of these sites. The loss in DPC supported DCPIP photoreduction coincides, intime, with the ageing-induced blue shift of the red absorptionband and thus suggests structure and function relations of theplastid membrane. (Received October 30, 1978; ) 相似文献
132.
The XC rat cell line was found to support the replication of a strain of the Moloney murine sarcoma-leukemia virus. In growth curve experiments cytopathology was paralleled by the production of murine sarcoma virus and leukemia virus progeny having the biologic, antigenic, and biophysical properties of the infecting virus. 相似文献
133.
Effect of hemodilution on RBC velocity, supply rate, and hematocrit in the cerebral capillary network. 总被引:7,自引:0,他引:7
A G Hudetz J D Wood B B Biswal I Krolo J P Kampine 《Journal of applied physiology》1999,87(2):505-509
The effect of isovolemic hemodilution on the circulation of red blood cells (RBCs) in the cerebrocortical capillary network was studied by intravital videomicroscopy with use of a closed-cranial-window technique in the rat. Velocity and supply rate of RBCs were measured by tracking the movement and counting the number of fluorescently labeled cells. Arterial blood was withdrawn in increments of 2 ml and replaced by serum albumin. Arterial blood pressure was maintained constant with an infusion of methoxamine. Both velocity and supply rate of RBCs increased, by approximately equal amounts, as arterial hematocrit was reduced from 44 to 15%. The maximum increase in RBC velocity was 4.6 and in RBC supply rate was 5.2 times the baseline value. Calculated lineal density of RBC, an index of capillary hematocrit, did not change with hemodilution. The results suggest that RBC flow and oxygen supply in the cerebral capillary network are maintained during isovolemic hemodilution. The "optimal hematocrit" is as low as 15%. 相似文献
134.
135.
In plants external stimuli are perceived through a cascade of signals and signal transduction pathways. Protein phosphorylation
and de-phosphorylation is one of the most important transduction paths for the perception of signals in plants. The highest
concentrations of plant phospho-proteins are located in chloroplasts. This facilitates the protection of thylakoid membranes
from stress-induced damage and augments adaptive strategies in plants. In this review, the protein kinases associated with
phosphorylation of thylakoid membrane protein, and the adaptive changes in thylakoid membrane architecture and developmental
cues are given. The presence of membrane bound kinases in thylakoid membranes have evolutionary implications for the signal
transduction pathways and the photosynthetic gene expression for thylakoid membrane protein dynamics.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
136.
The aim of the present study was to enhance the dissolution rate of gliclazide using its solid dispersions (SDs) with polyethylene
glycol (PEG) 6000. The phase solubility behavior of gliclazide in presence of various concentrations of PEG 6000 in 0.1 N
HCl was obtained at 37 °C. The solubility of gliclazide increased with increasing amount of PEG 6000 in water. Gibbs free
energy () values were all negative, indicating the spontaneous nature of gliclazide solubilization and they decreased with increase
in the PEG 6000 concentration, demonstrating that the reaction conditions became more favorable as the concentration of PEG
6000 increased. The SDs of gliclazide with PEG 6000 were prepared at 1:1, 1:2 and 1:5 (gliclazide/PEG 6000) ratio by melting-solvent
method and solvent evaporation method. Evaluation of the properties of the SDs was performed by using dissolution, Fourier-transform
infrared (FTIR) spectroscopy, differential scanning calorimetry (DSC) and X-ray diffraction (XRD) studies. The SDs of gliclazide
with PEG 6000 exhibited enhanced dissolution rate of gliclazide, and the rate increased with increasing concentration of PEG
6000 in SDs. Mean dissolution time (MDT)of gliclazide decreased significantly after preparation of SDs and physical mixture
with PEG 6000. The FTIR spectroscopic studies showed the stability of gliclazide and absence of well-defined gliclazide–PEG
6000 interaction. The DSC and XRD studies indicated the microcrystalline or amorphous state of gliclazide in SDs of gliclazide
with PEG 6000. 相似文献
137.
A new relaxed state has been characterized in the crystals of horse methemoglobin grown at neutral pH at low ionic concentration and their low humidity variants. The crystals provide an example for improvement in X-ray diffraction quality with reduced solvent content. Only the classical R state has been so far observed in liganded horse hemoglobin. The state characterized in the present study lies in between the R state and the R2 state characterized earlier in liganded human hemoglobin. The results presented here, along with those of earlier studies, suggest that relaxed and tense hemoglobin can access ensembles of states. 相似文献
138.
Plants may experience environmental stress factors operating in nature either simultaneously or in sequence. In the study, we have acclimated the developing primary leaves of wheat seedlings to high light stress and examined their photosynthetic response to polyethylene glycol (PEG) mediated osmotic stress during different developmental phases including senescence. The high light acclimated leaves show higher level of total carotenoids as compared to their non-acclimated counterparts experiencing osmotic stress during senescence. They also exhibit greater membrane stability as indicated by the measurements of fluorescence polarisation and energy transfer efficiency in photosystem I (PSI) and Photosystem II (PSII). From the data of DCPIP photoreduction and pulse amplitude modulated (PAM) fluorimetry, a similar trend is observed for PSII photochemistry of the leaves experiencing osmotic stress during senescence. Our results may suggest that the stress adaptive potential induced by one stress during development is retained by the leaves and helps to mitigate another stress effect operating in sequence during another developmental phase, namely senescence. 相似文献
139.
140.
Shivaprakash MR Rao P Mandal J Biswal M Gupta S Ray P Chakrabarti A 《Mycopathologia》2007,163(5):267-274
Nocardiosis, an uncommon infection of the past, is being increasingly reported in recent years with rise of immunosuppressed
patients. In India, very few centers have reported this disease. The present report describes twelve consecutive cases of
nocardiosis reported over a period of 26 months (January 2004 to March 2006) from a tertiary care center in north India. The
patients were predominantly males (75%) with age range of 8–65 years and mean age of 38.4 years. Eleven patients had known
underlying illness including renal transplantation, human immunodeficiency virus infection, and long-term steroid therapy.
One patient with cerebral nocardiosis had no detectable predisposing factor. Infection involved central nervous system (3
cases), lungs (5 cases), subcutaneous tissue (1 case), and anterior mediastinum (1 case). Disseminated infection was documented
in two patients. Nocardia asteroides complex was incriminated in six patients, N. brasiliensis in five and N. otitidiscaviarum in one patient. All the isolates were sensitive to co-trimoxazole, amikacin, cefotaxime and imipenem. Good therapeutic response
was observed in 10 (90.9%) of 11 patients treated with antibiotics including co-trimaxazole, cephalosporins, amikacin, and
imipenem alone or in combination. The series of nocardiosis reported from India has also been reviewed. 相似文献