全文获取类型
收费全文 | 775篇 |
免费 | 42篇 |
专业分类
817篇 |
出版年
2022年 | 4篇 |
2021年 | 15篇 |
2020年 | 11篇 |
2019年 | 9篇 |
2018年 | 27篇 |
2017年 | 14篇 |
2016年 | 26篇 |
2015年 | 22篇 |
2014年 | 42篇 |
2013年 | 50篇 |
2012年 | 59篇 |
2011年 | 57篇 |
2010年 | 38篇 |
2009年 | 31篇 |
2008年 | 39篇 |
2007年 | 34篇 |
2006年 | 44篇 |
2005年 | 36篇 |
2004年 | 28篇 |
2003年 | 35篇 |
2002年 | 20篇 |
2001年 | 13篇 |
2000年 | 25篇 |
1999年 | 17篇 |
1998年 | 6篇 |
1997年 | 10篇 |
1996年 | 4篇 |
1995年 | 3篇 |
1994年 | 5篇 |
1993年 | 5篇 |
1992年 | 5篇 |
1991年 | 2篇 |
1990年 | 6篇 |
1989年 | 6篇 |
1988年 | 3篇 |
1987年 | 4篇 |
1986年 | 7篇 |
1985年 | 5篇 |
1984年 | 6篇 |
1983年 | 9篇 |
1982年 | 4篇 |
1981年 | 11篇 |
1979年 | 4篇 |
1974年 | 2篇 |
1973年 | 2篇 |
1972年 | 3篇 |
1971年 | 1篇 |
1968年 | 1篇 |
1956年 | 1篇 |
1952年 | 1篇 |
排序方式: 共有817条查询结果,搜索用时 15 毫秒
1.
M R Giovagnoli P Di Fraia A Manna V Marafini C Valli P Marchei A Vecchione 《The International journal of biological markers》1989,4(1):13-17
We tested the presence of tumour polypeptide antigen (TPA) in lower urinary tract cells from 59 workers exposed to known bladder carcinogens and from 30 control subjects. We then correlated immunocytological expression and serum TPA levels. Lower urinary tract cells from 31 subjects gave either moderately or strongly positive immunocytological stains. Five also had high serum TPA. The detection of TPA by cytology and in serum differed significantly in workers exposed to cancer agents and the control group. 相似文献
2.
3.
Azospirillum strains isolated from the roots and rhizosphere of some plants growing in West Bengal were subjected to qualitative and quantitative
evaluation for poly-3-hydroxybutyrate (PHB) production. Out of the total 49 isolates, 13 (26%) were confirmed as PHB producers
according to staining and chemical assay methods. The majority of these strains belonged toAzospirillum brasilense butA. amazonense andA. lipoferum were also present. When grown in the presence of NH4Cl in the medium, the PHB content of the strains ranged from 1 to 14% of cell dry mass. The identity of the PHB extracted
fromAzospirillum strain 24P-N-72 was confirmed by the characteristic UV and IR absorption peaks at 235 nm and 1730 cm−1, respectively. 相似文献
4.
Dipak Kumar Banerjee 《Journal of biosciences》1987,11(1-4):311-319
Radio-labelled amphomycin (3H-amphomycin) forms a complex with dolichylmonophosphate in presence of Ca2+. Complex formation has also been documented with retinylmonophosphate and perhydromonoeneretinylmonophosphate. Analysis of
the space-filling model suggested both fatty acylated aspartic acid residue at the N-terminus of the lipopeptide and phosphate
head group of dolichylmonophosphate are necessary for the complex formation. The binding ability of amphomycin is then utilized
to localize dolichylmonophosphate in the microsomal membrane. Studies with microsomal membranes from hen oviduct suggested
that dolichylmonophosphate is located in the cytoplasmic side of the membrane. 相似文献
5.
Circadian rhythms in physiology and behavior are ultimately regulated at the hypothalamic level by the suprachiasmatic nuclei
(SCN). This central oscillator transduces photic information to the cellular clocks in the periphery through the autonomic
nervous system and the neuroendocrine system. The fact that these two systems have been shown to modulate leukocyte physiology
supports the concept that the circadian component is an important aspect of hypothalamic-immune communication. Circadian disruption
has been linked to immune dysregulation, and recent reports suggest that several circadian clock genes, in addition to their
time-keeping role, are involved in the immune response. In this overview, we summarize the findings demonstrating that Natural
Killer (NK) cell function is under circadian control.
Special issue article in honor of George Fink. 相似文献
6.
7.
Manna L Neglia G Marino M Gasparrini B Di Palo R Zicarelli L 《Zygote (Cambridge, England)》2003,11(1):17-22
The aim of this study was to identify a simple, rapid method for sex determination of in vitro produced buffalo embryos, amplifying Y-chromosome-specific repeat sequences by polymerase chain reaction (PCR). Buffalo oocytes collected from slaughtered animals were matured, fertilised and cultured in vitro for 7 days. On day 7 embryos were evaluated and divided in to six groups according to developmental stage (2, 4, 8, 16 cells, morulae and blastocyst). Each embryo was stored singly in phosphate-buffered saline at -20 degrees C until PCR. Two different methods of extraction of DNA were compared: a standard procedure (ST), using a normal extraction by phenol-chloroform, isoamyl alcohol and final precipitation in absolute ethanol and a direct procedure (DT), using a commercial kit (Qiaquik-Qiagen mini blood). A pair of bovine satellite primers and two pairs of different bovine Y-chromosome-specific primers (BRY4.a and BRY.1) were used in the PCR assay on embryos and on whole blood samples collected from male and female adult buffaloes, used as control. The trial was carried out on 359 embryos (193 for ST and 166 for DT). When DNA samples from blood were amplified, the sex determined by PCR always corresponded to the anatomical sex. Embryo sexing was not possible in two embryos in ST and one embryo in DT. Both extraction protocols recovered sufficient quantities of target DNA at all developmental stages, but the time required for the ST (24 h) limits its use in embryo sexing and supports the use of commercial extraction kits (5 h). 相似文献
8.
The purpose of this investigation was to evaluate the effect of formulation factors on in vitro permeation of moxifloxacin
from aqueous drop through freshly excised goat, sheep, and buffalo corneas. Aqueous isotonic ophthalmic solutions of moxifloxacin
hydrochloride of different concentrations (pH 7.2) or 0.5% (wt/vol) solutions of different pH or 0.5% solutions (pH 7.2) containing
different preservatives were made. Permeation characteristics of drug were evaluated by putting 1 mL formulation on freshly
excised cornea (0.50 cm2) fixed between donor and receptor compartments of an all-glass modified Franz diffusion cell and measuring the drug permeated
in the receptor (containing 10 mL bicarbonate ringer at 37°C under stirring) by spectrophotometry at 291 nm, after 120 minutes.
Statistical analysis was done by one-way analysis of variance (ANOVA) followed by Dunnett’s test. Increase in drug concentration
in the formulation resulted in an increase in the quantity permeated but a decrease in percentage permeation. Increase in
pH of the solution from 5.5 to 7.2 increased drug permeation, indicating pH-dependent transport. Compared with control formulation,
moxifloxacin 0.5% (wt/vol) solution (pH 7.2) containing disodium edetate (EDTA) (0.01% wt/vol) produced significantly (P<.05) higher permeation with all the corneas. Formulation with benzyl alcohol significantly (P<.05) increased permeation with buffalo cornea compared with its control. Presence of benzalkonium chloride (BAK) (0.01% wt/vol)
and EDTA (0.01% wt/vol) in the formulation increased permeation to the maximum with all the corneas. The results suggest that
moxifloxacin 0.5% ophthalmic solution (pH 7.2) containing BAK (0.01%) and EDTA (0.01%) provides increased in vitro ocular
availability through goat, sheep, and buffalo corneas.
Published: February 10, 2006
Formerly College of Pharmacy, University of Delhi, Pushp Vihar, Sector III, New Delhi-110017, India 相似文献
9.
Amelioration of cadmium-induced cardiac impairment by taurine 总被引:1,自引:0,他引:1
The present study has been designed to investigate the protective role of taurine (2-aminoethanesulfonic acid), a sulfur containing conditionally essential amino acid, against cadmium-induced cardiac dysfunction in mice. Cadmium chloride (CdCl(2)) was used as the source of cadmium and it was administered orally at a dose of 4mg/kg body weight for 6 days. Cadmium exposure caused significant accumulation of the cadmium and iron in mice hearts tissue. Levels of serum specific markers related to cardiac impairments, e.g. total cholesterol, HDL cholesterol and triglyceride were altered due to cadmium toxicity. Reduction in the activities of antioxidant enzymes, namely, superoxide dismutase (SOD), catalase (CAT), glutathione-S-transferase (GST), glutathione reductase (GR), glutathione peroxidase (GPx) and glucose-6-phosphate dehydrogenase (G6PD) have been observed in cadmium exposed mice. Cadmium intoxication also decreased the cardiac glutathione (GSH) and total thiols contents and increased the levels of oxidized glutathione (GSSG), lipid peroxidation end products, protein carbonyl content and the extent of DNA fragmentation. Oral administration of taurine at a dose of 100mg/kg body weight for 5 days, however, prevented all the toxin-induced oxidative impairments mentioned above. "Ferric Reducing/Antioxidant Power (FRAP) assay" showed that taurine could protect the cardiac tissue by preventing cadmium-induced reduction of the intracellular antioxidant power. Histological examination of cardiac segments also supported the beneficial role of taurine against cadmium-induced damages in the murine hearts. Effect of a well established antioxidant, vitamin C has been included in the study as a positive control. Combining all, results suggest that taurine attenuates cadmium-induced impairment in mice hearts. 相似文献
10.
Subhasish Ghosh Parimalendu Haldar Dipak Kumar Mandal 《Proceedings of the Zoological Society》2017,70(1):46-51
The growth of fishery and animal husbandry is being hindered by the scarcity of protein rich feed ingredients. Being rich in protein grasshoppers may be an alternative source of protein rich feed ingredients and hence rearing of these insects is essential for sustainable supply of insect biomass to the feed industry. The success of biomass production through insect rearing depends on the reproductive potentiality, rate of survival and growth of that particular insect. This study examines the biotic potential, fecundity, fertility, nymph mortality, life span and biomass production ability of a multivoltine grasshopper, Oxya hyla hyla (Serville, 1931) under semi-controlled condition. The grasshoppers are reared in 35 ± 2 °C temperature and 12L: 12D photoperiod and provided with food as fresh leaves of Cynodon dactylon (L.) Pers. to nymphs and Sorghum halepense (L.) Pers. to the adults. The result shows that a single pair of O. hyla hyla can lay on average 69.87 eggs in 4.96 ± 0.43 egg pods of which 7.37 ± 0.92 % eggs and 8.26 ± 0.99 % nymphs do not survive. The remaining survived nymphs metamorphose to 27.8 ± 3.35 male and 32.6 ± 3.21 female adults which produce a biomass of 18.48 ± 1.67 g wet weight. Thus a mass scale rearing of this insect may produce good amount of insect biomass which may be usable for fish and animal feed. 相似文献