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81.
Ghanem A Aboul-Enein MN El-Azzouny A El-Behairy MF Al-Humaidi E Alaidan AA Amin K Al-Ahdal MN 《Chirality》2008,20(8):871-877
The first straightforward lipase-catalyzed enantioselective access to enantiomerically enriched tiaprofenic acid as a versatile method in chiral separation of racemates is demonstrated. The latter was directly monitored by enantioselective HPLC using a 3,5-dimethylphenylcarbamate derivative of cellulose-based chiral stationary phase namely Chiralpak IB (the immobilized version of Chiralcel OD). Non-standard HPLC organic solvents were used as diluent to dissolve the "difficult to dissolve" enzyme substrate (the acid) and as eluent for the simultaneous enantioselective HPLC baseline separation of both substrate and product in one run without any further derivatization. The existence of a non-standard HPLC organic solvent (e.g., methyl tert-butyl ether) in the mobile phase composition is mandatory to accomplish the simultaneous enantioselective HPLC baseline separation of both substrate and product. 相似文献
82.
Mohamed Hashem Nabil A. Ibrahim Wfaa A. El-Sayed Shereef El-Husseiny Elham El-Enany 《Carbohydrate polymers》2009,78(3):502-510
1,2,3-Benzothiazole-7-thiocarboxylic acid-S-methylester (commercially known as Actigard® AM-87) was utilized to impart cotton fabric durable antimicrobial properties. Finishing treatment was carried out under a variety of conditions. The latter were included, effect of pH, concentration of antibacterial agents, curing temperature and curing time. The effect of fabric construction, mercerization, and dyeing with different dyestuff were also investigated. The study was also extended to investigate the technical feasibility of combining antimicrobial finishing treatment in question with other finishing treatment generally carried out on cotton fabric, like soft finishing and crease recovery finishing. The treated fabrics were monitored for antimicrobial properties before and after washing. The treated fabrics were also evaluated for the physio-mechanical properties like fabric tensile strength, elongation at break (or bursting strength for knitted fabric), wettability, crease recovery angle, whiteness index and roughness. Results obtained show that, the most appropriate conditions for treatment cotton fabric with Actigard® are: padding the cotton fabric in aqueous solution containing 6% Actigard® at pH 5 (adjusted using formic acid) then squeezed to wet pick up of 100%, dried at 80 °C for 5 min then cured at 100 °C for 150 s. The untreated cotton fabric did not show any antimicrobial activity towards Staphylococcus aureus or Escherichia coli. Treatment of cotton fabric with Actigard® improves its antimicrobial properties towards S. aureus or E. coli. It is also observed that, treatment of cotton fabric with Actigard® marginally decreases fabric tensile strength, elongation at break, roughness and WI, whereas; both wettability and crease recovery angle remain practically intact. This was observed whether the fabric was pre-mercerized or not. 相似文献
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Nabil Asaad Paul A. Bethel Michelle D. Coulson Jack E. Dawson Susannah J. Ford Stefan Gerhardt Matthew Grist Gordon A. Hamlin Michael J. James Emma V. Jones Galith I. Karoutchi Peter W. Kenny Andrew D. Morley Keith Oldham Neil Rankine David Ryan Stuart L. Wells Linda Wood Martin Augustin Stephan Krapp Stefan Steinbacher 《Bioorganic & medicinal chemistry letters》2009,19(15):4280-4283
A series of potent Cathepsin L inhibitors with good selectivity with respect to other cysteine Cathepsins is described and SAR is discussed with reference to the crystal structure of a protein-ligand complex. 相似文献
85.
Nabil M. Abdel-Hamid 《The Journal of membrane biology》2009,230(3):155-162
Chemical composition of extracellular matrix (ECM) plays a pivotal role in cellular and tissue development, regeneration,
and differentiation. It also plays a key role in pathogenesis of hepatocellular carcinoma (HCC). This study explored premalignant
changes in the liver tissue content of collagen (as hydroxyproline, HP), total glycosaminoglycans (TGAGs), free glucosamine
(FGA), total sialic acid (TSA), lysosomal membrane integrity variations (calculated as total and free cathepsin D activities),
and liver histology. Serum alfa-fetoprotein (AFP) level was used as an early marker for HCC in two groups of Wistar rats.
One group of rats served as control and was provided normal saline orally. The other group was provided trichloroacetic acid
(TCA) as 0.5 g/kg/day for five consecutive days by oral gavage. Animals were killed before tumor development. The treatment
revealed dysplastic changes in addition to microsteatosis (fatty changes). Both sinusoids and the portal vein among dysplastic
cells were dilated and congested. These dysplastic foci are believed to be premalignant and may be precancerous lesions. The
following things were observed: a highly significant increase in serum AFP (as a key marker for HCC), a significant decrease
in HP and TSA, a significant increase in FGA, nonsignificant decrease in TGAGs, significant up-regulation of free cathepsin
D, nonsignificant decrease in total cathepsin D activities, and destabilization of lysosomal membrane integrity. Down-regulation
of HP, TSA, and TGAGs seems to be a prerequisite for cancer development. This might be stimulated by up-regulation of free
cathepsin D activity. Perhaps tissue fibrosis is not a condition for developing HCC because collagen was significantly depressed.
Up-regulated FGA could be assumed to be a defense mechanism against TCA-induced proteolysis of membrane proteins because it
is frequently reported to be of value in cancer chemotherapy. Studied ECM perturbations can be assumed as preliminary changes
during chemical hepatocarcinogenesis at the tissue level. Prospective studies on blood levels of cathepsins, TGAGs, and individual
ECM variables such as TSA, FGA, and Hp in patients at risk for HCC, performed in parallel with assessments of AFP, may provide
a cost-effective way to find new links between tissue changes and circulation that would permit early prediction of disease.
It may also provide a way to monitor HCC and compensate for the missed peak AFP values. 相似文献
86.
87.
Defects in the expression of either BAFF (B cell activating factor) or BAFF-R impairs B cell development beyond the immature, transitional type-1 stage and thus, prevents the formation of follicular and marginal zone B cells, whereas B-1 B cells remain unaffected. The expression of BAFF-R on all mature B cells might suggest a role for BAFF-R signaling also for their in vivo maintenance. Here, we show that, 14 days following a single injection of an anti-BAFF-R mAb that prevents BAFF binding, both follicular and marginal zone B cell numbers are drastically reduced, whereas B-1 cells are not affected. Injection of control, isotype-matched but non-blocking anti-BAFF-R mAbs does not result in B cell depletion. We also show that this depletion is neither due to antibody-dependent cellular cytotoxicity nor to complement-mediated lysis. Moreover, prevention of BAFF binding leads to a decrease in the size of the B cell follicles, an impairment of a T cell dependent humoral immune response and a reduction in the formation of memory B cells. Collectively, these results establish a central role for BAFF-BAFF-R signaling in the in vivo survival and maintenance of both follicular and marginal zone B cell pools. 相似文献
88.
Nabil Mabrouk Guillaume Deffuant Tim Tolker-Nielsen Claude Lobry 《Theorie in den Biowissenschaften》2010,129(1):1-13
Recent experimental observations of Pseudomonas aeruginosa, a model bacterium in biofilm research, reveal that, under specific growth conditions, bacterial cells form patterns of interconnected
microcolonies. In the present work, we use an individual-based model to assess the involvement of bacteria motility and self-produced
extracellular substance in the formation of these patterns. In our simulations, the pattern of interconnected microcolonies
appears only when bacteria motility is reduced by excreted extracellular macromolecules. Immotile bacteria form isolated microcolonies
and constantly motile bacteria form flat biofilms. Based on experimental data and computer simulations, we suggest a mechanism
that could be responsible for these interconnected microcolonies. 相似文献
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90.