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   2378篇
  免费   202篇
  国内免费   49篇
耳鼻咽喉   14篇
儿科学   124篇
妇产科学   58篇
基础医学   279篇
口腔科学   57篇
临床医学   213篇
内科学   557篇
皮肤病学   34篇
神经病学   102篇
特种医学   217篇
外科学   145篇
综合类   113篇
一般理论   4篇
预防医学   217篇
眼科学   218篇
药学   119篇
中国医学   4篇
肿瘤学   154篇
  2023年   22篇
  2022年   27篇
  2021年   53篇
  2020年   36篇
  2019年   28篇
  2018年   39篇
  2017年   57篇
  2016年   62篇
  2015年   58篇
  2014年   97篇
  2013年   106篇
  2012年   85篇
  2011年   79篇
  2010年   93篇
  2009年   101篇
  2008年   90篇
  2007年   124篇
  2006年   112篇
  2005年   75篇
  2004年   62篇
  2003年   50篇
  2002年   38篇
  2001年   54篇
  2000年   46篇
  1999年   46篇
  1998年   84篇
  1997年   73篇
  1996年   65篇
  1995年   59篇
  1994年   46篇
  1993年   55篇
  1992年   42篇
  1991年   41篇
  1990年   41篇
  1989年   49篇
  1988年   55篇
  1987年   36篇
  1986年   50篇
  1985年   42篇
  1984年   41篇
  1983年   34篇
  1982年   22篇
  1981年   12篇
  1980年   18篇
  1979年   17篇
  1978年   17篇
  1977年   17篇
  1976年   20篇
  1975年   11篇
  1973年   7篇
排序方式: 共有2629条查询结果,搜索用时 15 毫秒
21.
Urticaria in response to various physical stimuli has been reported in sporadic and familial patterns. The most common of these physical urticarias, dermographism, is a localized urticarial response to stroking or scratching of the skin and has not been reported previously to be familial. A four-generation family with dermographism, probably inherited as an autosomal dominant trait, is presented along with a discussion of sporadic dermographism and other types of familial physical urticarias.  相似文献   
22.
Previous studies have suggested that human follicular fluid contains factors that reduce the zona-binding capacity of spermatozoa. The present study provides further evidence of the existence of such factors. Using the hemizona binding assay (HZA), we have shown that the inhibitory effect of human follicular fluid on the zona-binding capacity of spermatozoa is concentration-dependent, an inhibitory effect being detected when the concentration of human follicular fluid was > or = 10%. A 1% concentration of human follicular fluid did not possess this inhibitory activity. Heating human follicular fluid at 56 degrees C for 30 min did not affect its inhibitory properties; treatment with proteinase-K abolished such inhibition. Human follicular fluid was fractionated sequentially by concanavalin-A affinity chromatography, Mono Q ion-exchange chromatography and Superose-12 gel filtration. The zona binding inhibitory activity resided in the fraction which bound to the lectin and Mono Q column and contained molecules with native molecular weights of 32 and 192 kDa. Sodium dodecyl sulphate-polyacrylamide gel electrophoresis analysis suggested that the 192 kDa glycoprotein was a tetramer, while the 32 kDa glycoprotein remained as a single molecular species under denaturing conditions. We conclude that two glycoproteins were responsible for the zona binding inhibitory activity of human follicular fluid. The physiological role of these factors remains unclear.   相似文献   
23.
24.
25.
26.
The NAD-dependent glycerol-3-phosphate dehydrogenases (G3PDH, EC 1.1.1.8) of Trypanosoma brucei and Leishmania mexicana are thought to have different roles in carbohydrate metabolism. Here the physicochemical and kinetic properties of natural G3PDH from T. brucei with the recombinant homologue of L. mexicana which share 63% positional identity are compared. Despite their supposed different functions in energy metabolism of the parasites the two G3PDHs have remarkably similar properties, including pH optima and K(m) value for dihydroxyacetone phosphate (DHAP) and NADH in the formation of glycerol 3-phosphate (G3P) and for NAD+ and G3P in the reverse reaction. Both enzymes are subject inhibition by dihydroxyacetone phosphate at concentrations above 0.2 mM and are inhibited by the trypanocidal drugs suramin and melarsen oxide at sub-micromolar concentrations.  相似文献   
27.
28.
Penetrating injuries are a leading cause of unilateral visual loss in young patients. We reviewed the records of 197 patients aged 18 years or younger who underwent primary repair of a penetrating ocular injury at the Wilmer Ophthalmological Institute from January 1970 through December 1981. The injury was caused by sharp objects in 49% of cases, missiles in 35%, and blunt trauma in 14%. Of 159 patients with at least 6 months follow-up, 110 (69%) achieved final vision of 5/200 or better, and 77 patients (48%) achieved final visual acuity of 20/50 or better. The prognosis after a penetrating injury is strongly influenced by the nature of the injury and the extent of initial damage. Several factors were found to correlate with an unfavorable visual outcome, including: initial preoperative visual acuity of worse than 5/200, injuries due to blunt trauma, wounds involving the sclera, double penetrating injuries, dense vitreous hemorrhage, and wounds associated with an intraocular "BB" pellet.  相似文献   
29.
PurposePediatric gastrostomy tubes (G-tubes) are associated with considerable utilization of healthcare resources. G-tube dislodgement can result in tract disruption and abdominal sepsis. We aimed to reduce early G-tube dislodgement by 25%.MethodsAn interdisciplinary team convened to identify key drivers of G-tube dislodgement and implement initiatives to reduce this complication. A G-tube care bundle was implemented in 2018. Rates of early G-tube dislodgement (within 90 days of insertion) were tracked. 15 months of cases after bundle implementation were compared to 20 months of cases before implementation. Length of stay (LOS, balancing measure) and bundle compliance (process measure) were tracked.ResultsG-tube dislodgements decreased 47% after bundle implementation. Overall, dislodgements after G-tube insertion decreased from 43% to 19% dislodgements per tube inserted, p = 0.004. Reductions were observed for dislodgements occurring in both the inpatient (14% vs. 1.5%) and outpatient (29% vs. 18%) settings. Median LOS was reduced from 15.3 to 7.1 days following implementation, p = 0.004. Process measures demonstrated 75% or greater compliance one year after implementation.ConclusionAn interdisciplinary team using quality improvement science methodology can significantly reduce G-tube dislodgement and improve value after pediatric gastrostomy tube insertion.Type of studyLongitudinal cohort study.Level of evidenceIII.  相似文献   
30.
In summary, having data from other service areas available in a relational clinical database could resolve many of the problems existing in today's registry systems. Uniting sophisticated information systems into a centralized database system could definitely be a corporate asset in managing the bottom line.  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