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排序方式: 共有787条查询结果,搜索用时 187 毫秒
781.
Biology Bulletin - In our ongoing efforts to inventory the lepiotaceous fungi of Pakistan, we here report on two species, new to Pakistan: Lepiota cingulum is also new to Asia, and L. oreadiformis.... 相似文献
782.
Human vascular smooth muscle cells (VSMC) bind tissue plasminogen activator (tPA) specifically, saturably, and with relatively high affinity (K(d) 25 nM), and this binding potentiates the activation of cell-associated plasminogen (Ellis, V., and Whawell, S. A. (1997) Blood 90, 2312-2322). We have observed that this binding can be efficiently competed by DFP-inactivated tPA and S478A-tPA but not by tPA inactivated with H-D-Phe-Pro-Arg-chloromethyl ketone (PPACK). VSMC-bound tPA also exhibited a markedly reduced inhibition by PPACK, displaying biphasic kinetics with second-order rate constants of 7. 5 x 10(3) M(-1) s(-1) and 0.48 x 10(3) M(-1) s(-1), compared with 7. 2 x 10(3) M(-1) s(-1) in the solution phase. By contrast, tPA binding to fibrin was competed equally well by all forms of tPA, and its inhibition was unaltered. These effects were shown to extend to the physiological tPA inhibitor, plasminogen activator inhibitor 1. tPA.plasminogen activator inhibitor 1 complex did not compete tPA binding to VSMC, and the inhibition of bound tPA was reduced by 30-fold. The behavior of the various forms of tPA bound to VSMC correlated with conformational changes in tPA detected by CD spectroscopy. These data suggest that tPA binds to its specific high affinity site on VSMC by a novel mechanism involving the serine protease domain of tPA and distinct from its binding to fibrin. Furthermore, reciprocally linked conformational changes in tPA appear to have functionally significant effects on both the interaction of tPA with its VSMC binding site and the susceptibility of bound tPA to inhibition. 相似文献
783.
784.
Heba F. Salem Rasha M. Kharshoum Lekaa F. Abdel Hakim Mohamed E. Abdelrahim 《Journal of liposome research》2016,26(4):324-335
Purpose: Voriconazole has both low aqueous solubility and stability. We hypothesize that designing voriconazole in the form of a nano powder inhaler at a geometric diameter within 1–5?μm will enhance its stability and solubility. Therefore, we prepared nanoagglomerates of voriconazole which will collapse in the lungs to reform the nanoparticles.Method: The nanoparticles were formulated using both stearic acid and sodium deoxycholate as edge activators. Osmogenic polycation polyethyleneimine (PEI) was used to form agglomerates of controllable size.Results: Voriconazole nanoparticles and agglomerates showed a significant higher cumulative drug release than the pure powder (p?0.05) with R2?=?0.95. Small-sized particles were formed (353?nm), while their zeta potential was ?30.7?mV. The agglomerates were 2.7?μm in size and their zeta potential was ?20.9?mV. The formation of porous agglomerates was confirmed using a transmission electron microscope. Cascade impactor was used to evaluate the aerodynamic properties of the nanoparticles and the agglomerates. The aerodynamic characterization of the nanoparticles and the agglomerates resulted in a significant smaller mass median aerodynamic diameter (MMAD) (p?0.05) and higher fine particle dose (FPD) (p?0.01), fine particle fraction (FPF) (p?0.01), and total emitted dose (TED) (p?0.01) than the pure powder.Conclusion: The results suggest that using the combination of edge activators and diluted polycationic polymer solution provides porous voriconazole nanoagglomerates in a respirable range, which is proved successful in enhancing both the deposition and the dissolution of water insoluble-drugs in the lung. 相似文献
785.
786.
Ken’ichi Moto Salah Eldin Abdel Salam S. Sakurai M. Iwami 《Development genes and evolution》1999,209(7):447-450
A transgene reporter consisting of the bombyxin gene promoter and the green fluorescent protein coding region was introduced
into intact brains of the silkworm Bombyx mori by in vitro electroporation. After in vitro culture of the brains, the fluorescence derived from the introduced reporter
gene was observed in all cases in eight neurosecretory cells that had previously been identified as bombyxin-producing cells
(BPCs). Although the fluorescence was not always observed in all cells, it was specific to BPCs, indicating that the reporter
was under the control of the bombyxin gene promoter in a BPC-specific manner. Electroporatical introduction of a reporter
gene was therefore found to be a suitable method for analyzing cell-specific expression in intact tissues and to be substitute
for germ-line transmission of reporters in the transgenic system. Application of this technique enables us to analyze the
cell-specific expression of transgene reporters within a few days and treat more than several dozens of the reporters within
1 month, which is difficult to do with the transgenic system.
Received: 8 December 1998 / Accepted: 8 March 1999 相似文献
787.
G Ghanem B Loir M Hadley Z Abdel Malek A Libert V Del Marmol F Lejeune J Lozano J C García-Borron 《Peptides》1992,13(5):989-994
Our previous work indicated that IR-alpha-MSH (immunoreactive alpha-melanocyte-stimulating hormone) plasma levels are three times as high in melanoma patients with progressing disease than in disease-free patients, and that the melanoma tumor itself may be the source of IR-alpha-MSH. Further identification of the material in tumor extracts has been carried out in this study, and the results presented here show that the immunoreactivity is associated with a major fraction of about 16 kDa and another of 5-9 kDa. Significant amounts of the immunoreactive material were also found in human melanoma cells but not in culture supernatants. The presence of this material may be related to the melanogenic status of the tumor cells. We have estimated the intracellular IR-alpha-MSH to be within a 0.4 to 2.3 nM range in melanoma tumor cells. We have investigated the melanogenic effect of the IR-alpha-MSH material and its relationship to alpha-MSH. Purified extracts both from metastases and cultured cells were found to promote frog skin darkening as well as tyrosinase activity in Cloudman S91 melanoma cells. The IR material could also displace labeled alpha-MSH from its binding sites in human melanoma cells. Our data clearly indicate that melanoma cells engage in an autocrine production of alpha-MSH-like bioactive peptides by melanoma cells, of larger mol.wt., which are able to bind to MSH receptors. These peptides may be involved in the regulation of melanogenesis and possibly in the growth and proliferation of melanoma cells by an autocrine/paracrine mechanism. 相似文献