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141.
Plant and Soil - Struvite (MgNH4PO4·6H2O), a low water solubility (<3%) mineral that is increasingly recovered from wastewater treatment plants, has potential to be used as a slow... 相似文献
142.
Plant and Soil - Land cover change (LCC) from natural forest (NF) to plantations (PF) has occurred worldwide over the past several decades. However, the different LCC effects on soil aggregate C... 相似文献
143.
Eichinger Jonas F. Grill Maximilian J. Kermani Iman Davoodi Aydin Roland C. Wall Wolfgang A. Humphrey Jay D. Cyron Christian J. 《Biomechanics and modeling in mechanobiology》2021,20(5):1851-1870
Biomechanics and Modeling in Mechanobiology - Living soft tissues appear to promote the development and maintenance of a preferred mechanical state within a defined tolerance around a so-called set... 相似文献
144.
β-Glucan process-related impurities can be introduced into biopharmaceutical products via upstream or downstream processing or via excipients. This study obtained a comprehensive process-mapping dataset for five monoclonal antibodies to assess β-glucan introduction and clearance during development and production runs at various scales. Overall, 198 data points were available for analysis. The greatest β-glucan concentrations were found in the depth-filtration filtrate (37–2,745 pg/ml). Load volume correlated with β-glucan concentration in the filtrate, whereas flush volume was of secondary importance. Cation-exchange chromatography significantly cleared β-glucans. Furthermore, β-glucan leaching from the Planova 20N virus removal filter was reduced by increasing the flush volume (1 vs. 10 L/m2). β-glucan concentrations after filter flush with 10 L/m2 were consistently <10 pg/ml. No or only limited β-glucan clearance was attained via ultrafiltration/diafiltration (UF/DF). However, during the first run with monoclonal antibody (mAb) 4, β-glucan concentration in the UF/DF retentate was 10.8 pg/mg, potentially due to β-glucan leaching from the first run with a regenerated cellulose membrane. Overall, β-glucan levels in the final mAb drug substance were 1–12 pg/mg. Assuming high doses of 1,000–5,000 mg, a β-glucan contamination at 20 pg/mg would translate to 20–100 ng/dose, which is below the previously suggested threshold for product safety (≤500 ng/dose). 相似文献
145.
Ganapathi R. Revankar Roland K. Robins 《Nucleosides, nucleotides & nucleic acids》2013,32(5-6):709-724
Abstract A general and stereospecific method has been developed for the direct preparation of βD-ribofuranosyl, βD-arabinofuranosyl and 2-deoxy-βD-erythro-pentofuranosyl derivatives of a number of nitrogen heterocycles. The azoles thus far employed include appropriately substituted pyrrole, pyrazole, imidazole, 1,2,4-triazole, indole, imidazo[4,5-c]pyridine, pyrrolo[2,3-d]pyrimidine, pyrro10[3,2-c]pyridine, pyrrolo[4,2-c]pyrimidine, purine, pyrazolo[3,4-b]pyridine and pyrazolo-[3,4-d]pyrimidine. This simple high-yield methodology provided a facile route to the large-scale preparation of biologically significant nucleo-sides, such as 2′-deoxyribavirin, 2-chloro-2′-deoxyadenosine, tuber-cidin, Z'-deoxytubercidin, =sangivarnycin, 2′-deoxytoyocamycin, cade-guomycin, 2′-deoxycadeguomycin, G-cadeguomycin, kanagawamicin, 2′-deoxy-3-deazaguanosine, sG, brunfelsarnidine ribonucleoside and 2′-deoxyribofuranosyl derivative of the antibiotic SF-2140. This procedure appears to be considerably superior to the previously reported glycosylation methods. 相似文献
146.
Kandasamy Ramasamy Roland K. Robins Ganapathi R. Revankar 《Nucleosides, nucleotides & nucleic acids》2013,32(3):385-392
Abstract A synthesis of 2,4-dideazaribavirin ( 2 ), brunfelsamidine ribonucleoside ( 8c ) and certain related derivatives are described for the first time using the stereospecific sodium salt glycosylation procedure. Glycosylation of the sodium salt of pyrrole-3-carbonitrile ( 4 ) with 1-chloro-2, 3-O-t-isopropylidene-5-O-t-butyldimethylsilyl-α-D-ribofuranose ( 5 ) gave exclusively the corresponding blocked nucleoside ( 6 ) with β-anomeric configuration, which on deprotection provided 1-β-D-ribofuranosylpyrrole-3-carbonitrile ( 7 ). Functional group tranformation of 7 gave 2 , 8c and related 3-substituted pyrrole ribonucleosides. These compounds are devoid of any significant antiviral/antitumor activity invitro. 相似文献
147.
Roland K. Robins 《Nucleosides, nucleotides & nucleic acids》2013,32(3):205-231
Abstract A review of the potential role of cAMP and cGMP as hormonal regulators of tumor cell proliferation, metastases and lymphocyte activation reveals that several synthetic purine nucleoside 3′,5′-cyclic monophosphates are more potent and more selective in modulating certain specific responses than the parent natural cyclic nucleotides. cAMP derivatives have been prepared which will temporarily restore transformed cells to the normal phenotype. cAMP analogs may well be found which will selectively inhibit tumor metastases. Certain cGMP analogs could selectively stimulate the lymphocyte response toward the destruction of tumor cells. The synthesis of new cyclic nucleotides should provide unique nontoxic agents that could combat neoplasia on a hormonal basis. 相似文献
148.
Ganesh D. Kini William J. Hennen Roland K. Robins 《Nucleosides, nucleotides & nucleic acids》2013,32(3):581-587
Abstract A new, facile synthesis of 7-methyl-8-oxoguanosine is reported. 2-Chloro-7-methylpurine-6, 8-dione (5) was silylated with hexamethyldi-silazane and the silylated intermediate, 6, glycosylated with 1-0-acetyl-2, 3, 5-tri-0-benzoyl-D-ribofuranose to yield 2-chloro-7-methyl-9-(2′, 3′,-5′-tri-0-benzoyl-β-D-ribofuranosyl) purin-6, 8-dione (8). Deprotection of 8 with sodium hydroxide in aqueous methanol gave 2-chloro-7-methyl-9-(β-D-ribofuranosyl) purine-6,8-dione (9), which was aminated with liquid ammonia or methanolic ammonia to yield 7-methyl-8-oxoguanosine (3). 相似文献
149.
150.
Indrajit Chowdhury Winston E. Thompson Crystal Welch Kelwyn Thomas Roland Matthews 《Apoptosis : an international journal on programmed cell death》2013,18(12):1513-1525
Mammalian ovarian follicular development is tightly regulated by crosstalk between cell death and survival signals, which include both endocrine and intra-ovarian regulators. Whether the follicle ultimately ovulates or undergoes atresia is dependent on the expression and actions of factors promoting follicular cell proliferation, differentiation or apoptosis. Prohibitin (PHB) is a highly conserved, ubiquitous protein that is abundantly expressed in granulosa cells (GCs) and associated with GC differentiation and apoptosis. The current study was designed to characterize the regulation of anti-apoptotic and pro-apoptotic factors in undifferentiated rat GCs (gonadotropin independent phase) governed by PHB. Microarray technology was initially employed to identify potential apoptosis-related genes, whose expression levels within GCs were altered by either staurosporine (STS) alone or STS in presence of ectopically over-expressed PHB. Next, immunoblot studies were performed to examine the expression patterns of selective Bcl-2 family members identified by the microarray analysis, which are commonly regulated in the intrinsic-apoptotic pathway. These studies were designed to measure protein levels of Bcl2 family in relation to expression of the acidic isoform (phosphorylated) PHB and the components of MEK-Erk1/2 pathway. These studies indicated that over-expression of PHB in undifferentiated GCs inhibit apoptosis which concomitantly results in an increased level of the anti-apoptotic proteins Bcl2 and Bclxl, reduced release of cytochrome c from mitochondria and inhibition of caspase-3 activity. In contrast, silencing of PHB expression resulted in change of mitochondrial morphology from the regular reticular network to a fragmented form, which enhanced sensitization of these GCs to the induction of apoptosis. Collectively, these studies have provided new insights on the PHB-mediated anti-apoptotic mechanism, which occurs in undifferentiated GCs through a PHB → Mek-Erk1/2 → Bcl/Bcl-xL pathway and may have important clinical implications. 相似文献