全文获取类型
收费全文 | 679篇 |
免费 | 43篇 |
出版年
2023年 | 3篇 |
2022年 | 7篇 |
2021年 | 28篇 |
2020年 | 19篇 |
2019年 | 11篇 |
2018年 | 15篇 |
2017年 | 13篇 |
2016年 | 21篇 |
2015年 | 36篇 |
2014年 | 31篇 |
2013年 | 50篇 |
2012年 | 42篇 |
2011年 | 52篇 |
2010年 | 26篇 |
2009年 | 16篇 |
2008年 | 38篇 |
2007年 | 39篇 |
2006年 | 27篇 |
2005年 | 36篇 |
2004年 | 26篇 |
2003年 | 12篇 |
2002年 | 22篇 |
2001年 | 10篇 |
2000年 | 10篇 |
1999年 | 12篇 |
1998年 | 6篇 |
1997年 | 3篇 |
1996年 | 5篇 |
1995年 | 7篇 |
1994年 | 7篇 |
1993年 | 3篇 |
1992年 | 10篇 |
1991年 | 7篇 |
1990年 | 4篇 |
1989年 | 7篇 |
1988年 | 4篇 |
1985年 | 7篇 |
1983年 | 3篇 |
1982年 | 4篇 |
1981年 | 6篇 |
1979年 | 2篇 |
1978年 | 4篇 |
1977年 | 2篇 |
1976年 | 5篇 |
1975年 | 2篇 |
1974年 | 8篇 |
1973年 | 3篇 |
1972年 | 3篇 |
1965年 | 1篇 |
1954年 | 1篇 |
排序方式: 共有722条查询结果,搜索用时 15 毫秒
1.
There are currently only a few theoretical studies on convective heat transfer in polymer nanocomposites. In this paper, the unsteady incompressible flow of a polymer nanocomposite represented by an Oldroyd-B nanofluid along a stretching sheet is investigated. Recent studies have assumed that the nanoparticle fraction can be actively controlled on the boundary, similar to the temperature. However, in practice, such control presents significant challenges and in this study the nanoparticle flux at the boundary surface is assumed to be zero. We have used a relatively novel numerical scheme; the spectral relaxation method to solve the momentum, heat and mass transport equations. The accuracy of the solutions has been determined by benchmarking the results against the quasilinearisation method. We have conducted a parametric study to determine the influence of the fluid parameters on the heat and mass transfer coefficients. 相似文献
2.
Miilena M. Awad Amy E. Bryant Dennis L. Stevens Julian I. Rood 《Molecular microbiology》1995,15(2):191-202
The pathogenesis of clostridial myonecrosis, or gas gangrene, involves the growth of the anaerobic bacterium Clostridium perfringens in the infected tissues and the elaboration of numerous extracellular toxins and enzymes. The precise role of each of these toxins in tissue invasion and necrosis has not been determined. To enable genetic approaches to be used to study C. perfringens pathogenesis we developed an allelic exchange method which involved the transformation of C. perfringens cells with a suicide plasmid carrying a gene insertionally inactivated with an erythromycin-resistance determinant. The frequency with which double reciprocal crossover events were observed was increased to a workable level by increasing the amount of homologous DNA located on either side of the inactivated gene. Allelic exchange was used to isolate mutations in the‘chromosomal pfoA gene, which encodes an oxygen-labile haemolysin known as Θ-toxin or perfringolysin O. and in the chromosomal pic gene, which encodes the α-toxin or phospholipase C. The resultant mutants failed to produce detectable Θ-toxin or α-toxin activity, respectively, and could be complemented by recombinant plasmids that carried the respective wild-type genes. The resultant strains were virulence tested in a mouse myonecrosis model. The results showed that the pic mutants had demonstrably reduced virulence and therefore provided definitive genetic evidence for the essential role of α-toxin in gas gangrene or clostridial myonecrosis. 相似文献
3.
Pascale Simard Hugo Galarneau Sébastien Marois Daniel Rusu Caroline D Hoemann Patrice E Poubelle Hani El-Gabalawy Maria JG Fernandes 《Arthritis research & therapy》2009,11(3):R74-10
Introduction
Osteoarthritis is characterized by the progressive destruction of cartilage in the articular joints. Novel therapies that promote resurfacing of exposed bone in focal areas are of interest in osteoarthritis because they may delay the progression of this disabling disease in patients who develop focal lesions. Recently, the addition of 80% deacetylated chitosan to cartilage microfractures was shown to promote the regeneration of hyaline cartilage. The molecular mechanisms by which chitosan promotes cartilage regeneration remain unknown. Because neutrophils are transiently recruited to the microfracture site, the effect of 80% deacetylated chitosan on the function of neutrophils was investigated. Most studies on neutrophils use preparations of chitosan with an uncertain degree of deacetylation. For therapeutic purposes, it is of interest to determine whether the degree of deacetylation influences the response of neutrophils to chitosan. The effect of 95% deacetylated chitosan on the function of neutrophils was therefore also investigated and compared with that of 80% deacetylated chitosan. 相似文献4.
Rawia M. Khalil Ghada A. Abdelbary Mona Basha Ghada E. A. Awad Hadeer A. El-Hashemy 《Journal of liposome research》2017,27(2):118-129
The current investigation aims to develop and evaluate novel ocular proniosomal gels of lomefloxacin HCl (LXN); in order to improve its ocular bioavailability for the management of bacterial conjunctivitis. Proniosomes were prepared using different types of nonionic surfactants solely and as mixtures with Span 60. The formed gels were characterized for entrapment efficiency, vesicle size, and in vitro drug release. Only Span 60 was able to form stable LXN-proniosomal gel when used individually while the other surfactants formed gels only in combination with Span 60 at different ratios. The optimum proniosomal gel; P-LXN 7 (Span 60:Tween 60, 9:1) appeared as spherical shaped vesicles having high entrapment efficiency (>80%), appropriate vesicle size (187?nm) as well as controlled drug release over 12?h. Differential scanning calorimetry confirmed the amorphous nature of LXN within the vesicles. Stability study did not show any significant changes in entrapment efficiency or vesicle size after storage for 3 months at 4?°C. P-LXN 7 was found to be safe and suitable for ocular delivery as proven by the irritancy test. The antibacterial activity of P-LXN 7 evaluated using the susceptibility test and topical therapy of induced ocular conjunctivitis confirmed the enhanced antibacterial therapeutic efficacy of the LXN-proniosomal gel compared to the commercially available LXN eye drops. 相似文献
5.
Mounira Ben Farhat Ameny Farhat Wacim Bejar Radhouan Kammoun Kameleddine Bouchaala Amin Fourati Hani Antoun Samir Bejar Hichem Chouayekh 《Archives of microbiology》2009,191(11):815-824
The mineral phosphate solubilizing (MPS) ability of a Serratia marcescens strain, namely CTM 50650, isolated from the phosphate mine of Gafsa, was characterized on a chemically defined medium (NBRIP
broth). Various insoluble inorganic phosphates, including rock phosphate (RP), calcium phosphate (CaHPO4), tri-calcium phosphate (Ca3(PO4)2) and hydroxyapatite were tested as sole sources of phosphate for bacterial growth. Solubilization of these phosphates by
S. marcescens CTM 50650 was very efficient. Indeed, under optimal conditions, the soluble phosphorus (P) concentration it produced reached
967, 500, 595 and 326 mg/l from CaHPO4, Ca3(PO4)2, hydroxyapatite and RP, respectively. Study of the mechanisms involved in the MPS activity of CTM 50650, showed that phosphate
solubilization was concomitant with significant drop in pH. HPLC-analysis of culture supernatants revealed the secretion of
gluconic acid (GA) resulting from direct oxidation pathway of glucose when the CTM 50650 cells were grown on NBRIP containing
glucose as unique carbon source. This was correlated with the simultaneous detection by PCR for the first time in a S. marcescens strain producing GA, of a gene encoding glucose dehydrogenase responsible for GA production, as well as the genes pqqA, B, C and E involved in biosynthesis of its PQQ cofactor. This study is expected to lead to the development of an environmental-friendly
process for fertilizer production considering the capacity of S. marcescens CTM 50650 to achieve yields of P extraction up to 75% from the Gafsa RP. 相似文献
6.
The benign chondroblastoma is rarely located at the leg and hand bones. The reported case had a deformation of the first phalanx of the left leg second finger, clinico-radiologically diagnosed as a chondroma, and only the histopathological examination sets the diagnosis of benign chondroblastoma. 相似文献
7.
Release Mechanisms Behind Polysaccharides-Based Famotidine Controlled Release Matrix Tablets 总被引:1,自引:0,他引:1
Enas M. Elmowafy Gehanne A. S. Awad Samar Mansour Abd El-Hamid A. El-Shamy 《AAPS PharmSciTech》2008,9(4):1230-1239
Polysaccharides, which have been explored to possess gelling properties and a wide margin of safety, were used to formulate
single-unit floating matrix tablets by a direct compression technique. This work has the aim to allow continuous slow release
of famotidine above its site of absorption. The floating approach was achieved by the use of the low density polypropylene
foam powder. Polysaccharides (κ-carrageenan, gellan gum, xyloglucan, and pectin) and blends of polysaccharides (κ-carrageenan
and gellan gum) and cellulose ethers (hydroxypropylmethyl cellulose, hydroxypropylcellulose, sodium carboxymethyl cellulose)
were tried to modulate the release characteristics. The prepared floating tablets were evaluated for their floating behavior,
matrix integrity, swelling studies, in vitro drug release studies, and kinetic analysis of the release data. The differential scanning calorimetry and Fourier transform
infrared spectroscopy studies revealed that changing the polymer matrix system by formulation of polymers blends resulted
in formation of molecular interactions which may have implications on drug release characteristics. This was obvious from
the retardation in drug release and change in its mechanistics. 相似文献
8.
Based on its proven anabolic effects on bone in osteoporosis patients, recombinant parathyroid hormone (PTH1-34) has been evaluated as a potential therapy for skeletal repair. In animals, the effect of PTH1-34 has been investigated in various skeletal repair models such as fractures, allografting, spinal arthrodesis and distraction
osteogenesis. These studies have demonstrated that intermittent PTH1-34 treatment enhances and accelerates the skeletal repair process via a number of mechanisms, which include effects on mesenchymal
stem cells, angiogenesis, chondrogenesis, bone formation and resorption. Furthermore, PTH1-34 has been shown to enhance bone repair in challenged animal models of aging, inflammatory arthritis and glucocorticoid-induced
bone loss. This pre-clinical success has led to off-label clinical use and a number of case reports documenting PTH1-34 treatment of delayed-unions and non-unions have been published. Although a recently completed phase 2 clinical trial of PTH1-34 treatment of patients with radius fracture has failed to achieve its primary outcome, largely because of effective healing
in the placebo group, several secondary outcomes are statistically significant, highlighting important issues concerning the
appropriate patient population for PTH1-34 therapy in skeletal repair. Here, we review our current knowledge of the effects of PTH1-34 therapy for bone healing, enumerate several critical unresolved issues (e.g., appropriate dosing regimen and indications)
and discuss the long-term potential of this drug as an adjuvant for endogenous tissue engineering. 相似文献
9.
Jun Zhu Serguei Stepaniants Chunsheng Zhang Qingying Meng Mette Peters Yudong He Chester Ni Deborah Slipetz Michael A Crackower Hani Houshyar Christopher M Tan Ernest Asante‐Appiah Gary O'Neill Mingjuan Jane Luo Rolf Thieringer Jeffrey Yuan Chi‐Sung Chiu Pek Yee Lum John Lamb Yves Boie Hilary A Wilkinson Eric E Schadt Hongyue Dai Christopher Roberts 《Molecular systems biology》2012,8(1)
Common inflammatome gene signatures as well as disease‐specific signatures were identified by analyzing 12 expression profiling data sets derived from 9 different tissues isolated from 11 rodent inflammatory disease models. The inflammatome signature significantly overlaps with known drug targets and co‐expressed gene modules linked to metabolic disorders and cancer. A large proportion of genes in this signature are tightly connected in tissue‐specific Bayesian networks (BNs) built from multiple independent mouse and human cohorts. Both the inflammatome signature and the corresponding consensus BNs are highly enriched for immune response‐related genes supported as causal for adiposity, adipokine, diabetes, aortic lesion, bone, muscle, and cholesterol traits, suggesting the causal nature of the inflammatome for a variety of diseases. Integration of this inflammatome signature with the BNs uncovered 151 key drivers that appeared to be more biologically important than the non‐drivers in terms of their impact on disease phenotypes. The identification of this inflammatome signature, its network architecture, and key drivers not only highlights the shared etiology but also pinpoints potential targets for intervention of various common diseases. 相似文献
10.
Azemi Nur Farah Hani Misnan Rosmilah Keong Bun Poh Mokhtar Marina Kamaruddin Nurhaida Fah Wong Chee Yadzir Zailatul Hani Mohamad Yadzir Hani Mohamad Bakhtiar Faizal Abdullah Noormalin Arip Masita Ateshan Haidr Msahir 《Molecular biology reports》2021,48(10):6709-6718
Molecular Biology Reports - Tropomyosin is a major allergen in crustaceans, including mud crab species, but its molecular and allergenic properties in Scylla olivacea are not well known. Thus, this... 相似文献