首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   2845篇
  免费   165篇
  国内免费   12篇
耳鼻咽喉   23篇
儿科学   47篇
妇产科学   34篇
基础医学   470篇
口腔科学   41篇
临床医学   318篇
内科学   487篇
皮肤病学   19篇
神经病学   291篇
特种医学   168篇
外科学   545篇
综合类   10篇
一般理论   1篇
预防医学   238篇
眼科学   8篇
药学   184篇
肿瘤学   138篇
  2024年   2篇
  2023年   17篇
  2022年   28篇
  2021年   78篇
  2020年   57篇
  2019年   87篇
  2018年   70篇
  2017年   68篇
  2016年   71篇
  2015年   84篇
  2014年   141篇
  2013年   179篇
  2012年   233篇
  2011年   245篇
  2010年   132篇
  2009年   138篇
  2008年   184篇
  2007年   208篇
  2006年   190篇
  2005年   175篇
  2004年   157篇
  2003年   114篇
  2002年   114篇
  2001年   17篇
  2000年   19篇
  1999年   23篇
  1998年   35篇
  1997年   26篇
  1996年   19篇
  1995年   22篇
  1994年   13篇
  1993年   14篇
  1991年   8篇
  1990年   5篇
  1989年   9篇
  1988年   4篇
  1987年   3篇
  1986年   4篇
  1985年   5篇
  1984年   2篇
  1983年   4篇
  1982年   1篇
  1981年   4篇
  1980年   5篇
  1978年   5篇
  1977年   1篇
  1975年   1篇
  1922年   1篇
排序方式: 共有3022条查询结果,搜索用时 21 毫秒
1.
The aim of the current research project was to explore the possibilities of combining pressurized carbon dioxide with hot stage extrusion during manufacturing of solid dispersions of itraconazole and polyvinylpyrrolidone-co-vinyl acetate 64 (PVP-VA 64) and to evaluate the ability of the pressurized gas to act as a temporary plasticizer as well as to produce a foamed extrudate. Pressurized carbon dioxide was injected into a Leistritz Micro 18 intermeshing co-rotating twin-screw melt extruder using an ISCO 260D syringe pump. The physicochemical characteristics of the extrudates with and without injection of carbon dioxide were evaluated with reference to the morphology of the solid dispersion and dissolution behaviour and particle properties. Carbon dioxide acted as plasticizer for itraconazole/PVP-VA 64, reducing the processing temperature during the hot stage extrusion process. Amorphous dispersions were obtained and the solid dispersion was not influenced by the carbon dioxide. Release of itraconazole from the solid dispersion could be controlled as a function of processing temperature and pressure. The macroscopic morphology changed to a foam-like structure due to expansion of the carbon dioxide at the extrusion die. This resulted in increased specific surface area, porosity, hygroscopicity and improved milling efficiency.  相似文献   
2.
BACKGROUND: Acne is a multifactorial disease exhibiting distinct clinical presentations. Among them, the catamenial type is a matter of concern for young women. Some oral contraceptives may help without, however, clearing the skin condition. AIM: The present open study aimed at evaluating the effect of overnight applications of a paste made of petrolatum,15% zinc oxide and 0.25% miconazole nitrate. METHOD: The split-face trial was conducted in 35 women. A non-medicated cream was used as control. Clinical evaluations and biometrological assessments on cyanoacrylate follicular biopsies were performed monthly for 3 months. Comedometry and the density in autofluorescent follicular casts were used as analytical parameters. In addition, the five most severe cases at inclusion were tested at the completion of the study for follicular bacterial viability using dual flow cytometry. RESULTS: Compared with baseline and to the control hemi-face, the medicated paste brought significant improvement of acne. The number of papules and their redness were reduced beginning with the first treatment phase. A reduction in the follicular fluorescence was yielded beginning with the second treatment phase. The ratios between injured and dead bacteria, on the one hand, and live bacteria, on the other hand were significantly increased at completion of the study. CONCLUSION: A miconazole paste applied for 1 week at the end of the ovarian cycle has a beneficial effect on catamenial acne.  相似文献   
3.
Study Objective . To compare the pharmacokinetics of a single 100-mg oral dose of itraconazole administered as 10 ml of a 10-mg/ml itraconazole solution in hydroxypropyl-β-cyclodextrin under fasting versus postprandial conditions. Design . Open-label, two-way, randomized, crossover study. Setting . Janssen Research Foundation, Belgium. Patients . Twelve healthy volunteers. Interventions . Blood samples were obtained for pharmacokinetic analyses immediately before dosing and at regular intervals up to 96 hours after each dose. Blood and urine samples were obtained for hematologic, biochemical, and urinary safety analyses at baseline and at the end of the study. Measurements and Main Results . The mean peak plasma concentrations of both itraconazole and its active metabolite hydroxy-itraconazole were significantly higher under fasting conditions than under postprandial conditions. The mean times to peak concentration for both the parent compound and its metabolite were significantly shorter under fasting than under nonfasting conditions. The mean areas under the curve (AUC0–∞ and AUC0–24 hrs) were also significantly higher under fasting than under postprandial conditions. Conclusions . Our findings suggest that the higher bioavailability of this new formulation of itraconazole may be of benefit in seriously ill patients who are not able to ingest adequate quantities of food. The fact that the solution was also well tolerated and was not associated with clinically significant changes in any laboratory value further underscores the potential utility of this dosing form.  相似文献   
4.
5.
Genetic linkage studies have indicated that chromosome 14q24.3harbours a major locus for early-onset (onset age <65 years)Alzheimer's disease (AD3). Positional cloning efforts have identifieda novel gene S182 or presenilin 1 as the AD3 gene. We have mappedS182 in the AD3 candidate region between D14S277 and D14S284defined by genetic linkage studies in the two chromosome 14linked, early-onset AD families AD/A and AD/B. We have shownthat S182 is expressed in lymphoblasts and have determined thecomplete cDNA in both brain and lymphoblasts by RT-PCR sequencing.S182 is alternatively spliced in both brain and lymphoblastswithin a putative phosphorylation site located 5' in the codingregion. We identified two novel mutations, Ile143Thr and Gly384Alalocated in, respectively, the second transmembrane domain andin the sixth hydrophilic loop of the putative transmembranestructure of S182. As families AD/A and AD/B have a very similarAD phenotype our observation of two mutations in functionallydifferent domains suggest that onset age and severity of ADmay not be very helpful predictors of the location of putativeS182 mutations.  相似文献   
6.
Alternatively activated macrophages (aaMphi) display molecular and biological characteristics that differ from those of classically activated macrophages (caMphi). Recently, we described an experimental model of murine trypanosomosis in which the early stage of infection of mice with a Trypanosoma brucei brucei variant is characterized by the development of caMphi, whereas in the late and chronic stages of infection, aaMphi develop. In the present study, we used suppression subtractive hybridization (SSH) to identify genes that are expressed differentially in aaMphi versus caMphi elicited during infection with this T. b. brucei variant. We show that FIZZ1 and Ym1 are induced strongly in in vivo- and in vitro-elicited aaMphi as compared with caMphi. Furthermore, we demonstrate that the in vivo induction of FIZZ1 and Ym1 in macrophages depends on IL-4 and that in vitro, IFN-gamma antagonizes the effect of IL-4 on the expression of FIZZ1 and Ym1. Collectively, these results open perspectives for new insights into the functional properties of aaMphi and establish FIZZ1 and Ym1 as markers for aaMphi.  相似文献   
7.
8.
Skeletal homeostasis critically depends on the proper anabolic functioning of osteolineage cells. Proliferation and matrix synthesis are highly demanding in terms of biosynthesis and bioenergetics, but the nutritional requirements that support these processes in bone-forming cells are not fully understood. Here, we show that glutamine metabolism is a major determinant of osteoprogenitor function during bone mass accrual. Genetic inactivation of the rate-limiting enzyme glutaminase 1 (GLS1) results in decreased postnatal bone mass, caused by impaired biosynthesis and cell survival. Mechanistically, we uncovered that GLS1-mediated glutamine catabolism supports nucleotide and amino acid synthesis, required for proliferation and matrix production. In addition, glutamine-derived glutathione prevents accumulation of reactive oxygen species and thereby safeguards cell viability. The pro-anabolic role of glutamine metabolism was further underscored in a model of parathyroid hormone (PTH)-induced bone formation. PTH administration increases glutamine uptake and catabolism, and GLS1 deletion fully blunts the PTH-induced osteoanabolic response. Taken together, our findings indicate that glutamine metabolism in osteoprogenitors is indispensable for bone formation. © 2020 American Society for Bone and Mineral Research (ASBMR).  相似文献   
9.
10.
This review reports on multiple epiphyseal dysplasia (MED), first described clinically in the early part of the 20th century. Over 50 years later, we are now beginning to unravel the mystery behind the genetic mutations involved in triggering the changes in cartilage observed in this condition. In the past decade considerable progress has been made in identifying the underlying genetic defect in some forms of MED. Understanding the precise effect that these molecular changes have on the integrity of the cartilage extracellular matrix will lead the way in identifying the complex disease pathophysiology that defines MED. In addition, a greater understanding of the role and interactions of specific cartilage molecules may reveal the basis of more widespread cartilage disorders such as osteoarthritis.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号