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   4768篇
  免费   531篇
  国内免费   70篇
耳鼻咽喉   34篇
儿科学   141篇
妇产科学   72篇
基础医学   695篇
口腔科学   89篇
临床医学   626篇
内科学   916篇
皮肤病学   46篇
神经病学   253篇
特种医学   354篇
外科学   633篇
综合类   145篇
一般理论   1篇
预防医学   495篇
眼科学   44篇
药学   348篇
肿瘤学   477篇
  2021年   81篇
  2020年   43篇
  2019年   69篇
  2018年   59篇
  2017年   70篇
  2016年   89篇
  2015年   82篇
  2014年   118篇
  2013年   134篇
  2012年   192篇
  2011年   197篇
  2010年   127篇
  2009年   139篇
  2008年   161篇
  2007年   197篇
  2006年   186篇
  2005年   200篇
  2004年   156篇
  2003年   137篇
  2002年   130篇
  2001年   144篇
  2000年   143篇
  1999年   134篇
  1998年   107篇
  1997年   96篇
  1996年   94篇
  1995年   101篇
  1994年   69篇
  1993年   62篇
  1992年   113篇
  1991年   94篇
  1990年   109篇
  1989年   135篇
  1988年   104篇
  1987年   98篇
  1986年   88篇
  1985年   108篇
  1984年   77篇
  1983年   47篇
  1982年   55篇
  1981年   42篇
  1980年   51篇
  1979年   49篇
  1977年   64篇
  1976年   44篇
  1973年   43篇
  1972年   44篇
  1971年   47篇
  1970年   56篇
  1968年   43篇
排序方式: 共有5369条查询结果,搜索用时 15 毫秒
71.
Aerosol delivery in lung disease   总被引:1,自引:0,他引:1  
Metered-dose inhalers are the preferred method of aerosol delivery under normal circumstances because of their convenient size, ease of use and better patient compliance. Where poor coordination exists a spacer device, breath-activated inhaler or powder inhalation should be used and if muscular weakness presents a problem a Haleraid should be tried. A clinical air pump with jet nebuliser is appropriate if these methods prove unsatisfactory; where wet aerosol has been shown to result in clearly superior effects; for very small children; and for the "brittle" asthmatic prone to sudden life-threatening attacks, especially patients living in isolated conditions. Regular checks on aerosol techniques and efficacy of therapy are important aspects of follow up and education of all patients with airflow obstruction.  相似文献   
72.
Antagonist properties of d-LSD at 5-hydroxytryptamine2 receptors   总被引:1,自引:0,他引:1  
The hallucinogenic agent d-lysergic acid diethylamide (d-LSD) interacts with a number of serotonin (5-hydroxytryptamine [5-HT]) receptor subtypes in the central nervous system. It has been hypothesized that hallucinosis is produced by agonist activity at 5-HT2 receptors. There exist, however, numerous data from radioligand binding, cellular, smooth muscle, and behavioral studies that suggest that d-LSD is a potent 5-HT2 antagonist. These data are reviewed in this report. In addition, d-LSD displays agonist activity at 5-HT1A and 5-HT1C receptor subtypes, as determined in biochemical studies. At the present time, agonist interactions at 5-HT1C receptors, as opposed to 5-HT2 receptors, appears to be a more likely "common mechanism of action" of hallucinogenic agents.  相似文献   
73.
74.
75.
Although reliable antibodies are available that distinguishhuman suppressor T (Ts) cells from CTL and other T cells, feware available for murine Ts cells. We have developed a mAb (984D4.6.5)that, in the presence of complement, depletes alloantigen-specificTs cells but not CTL. This antibody recognizes activated TTscells but not their precursors. In these studies, flow cytometricanalysis demonstrates that 984D4.6.5 reacts with several Tscell hybridomas, cloned Th cell lines and WEHI-3 (a myelomonocytictumor cell line). Reactivity was not detected with BW5147, Thcell hybridomas, cloned Th cells, CTL lines and hybridomas,B cell lines, thymocytes, splenocytes, bone marrow cells nora variety of tumor cells. Among 984D4.6.5 positive lines, expressionis heterogeneous and the number of cells expressing high levelsof the epitope is increased when the hybridomas are maintainedat a relatively high cell density. Neuriminidase and pronasedeplete the epitope recognized by mAb 984D4.6.5. Protein synthesisand glycosylation inhibitors also reduce expression of thisepitope. These observations suggest that the epitope recognizedby 984D4.6.5 is a carbohydrate linked to a polypeptide. Thisantibody was tested by ELISA for binding to a large panel ofcarbohydrates and glycollpids coupled to BSA. The only one thatbound 984D4.6.5 was LS tetrasaccharide c (NeuNAc2-6Galpß1-4GIcNAcß1-3GaIß1-4Glc),an O-linked carbohydrate. Comparative analysis shows that boththe sequence and the linkage of these sugars are essential tothe reactivity with the 984D4.6.5 antibody. This epitope isexpressed by a glycoprotein of-200 kDa, as shown by Westernblots. The identity of this glycoprotein remains to be determined,but indirect evidence suggests that it is not CD45.  相似文献   
76.
77.
Pierce C 《Health data management》1995,3(8):65-6, 69-70
A growing number of the nation's 67 Blue Cross and Blue Shield plans, many of which are dominant health insurers in their markets, are attempting to expand their electronic health care transactions business. At least a dozen plans have created claims clearinghouses designed to handle claims and other electronic transactions destined for any payer.  相似文献   
78.
The purpose of this investigation was to study the efficacy of two dietary supplements on measures of body mass, body composition, and performance in 42 American football players. Group CM (n = 9) received creatine monohydrate, Group P (n = 11) received calcium pyruvate, Group COM (n = 11) received a combination of calcium pyruvate (60%) and creatine (40%), and Group PL received a placebo. Tests were performed before (T1) and after (T2) the 50 week supplementation period, during which the subjects continued their normal training schedules. Compared to P and PL, CM and COM showed significantly greater increases for body mass, lean body mass, 1 repetition maximum (RM) bench press, combined 1 RM squat and bench press, and static vertical jump (SVJ) power output. Peak rate of force development for SVJ was significantly greater for CM compared to P and PL. Creatine and the combination supplement enhanced training adaptations associated with body mass/composition, maximum strength, and SVJ; however, pyruvate supplementation alone was ineffective.  相似文献   
79.
A modern malaise   总被引:1,自引:0,他引:1  
JS Robertson Dr   《Public health》1999,113(4):155-156
  相似文献   
80.
We investigated predictors of change in plasma carotenoids from baseline to 3 y and examined plasma carotenoid concentrations at 1 and 3 y in response to a high vegetable diet. Participants were 56 women diagnosed with breast cancer and enrolled in a randomized feasibility study for a trial examining the effect of a diet high in vegetables and fruits on the risk of breast cancer recurrence. Independent t test analysis revealed that the intervention group had significantly higher vegetable and fruit servings and fiber at 12 mo and significantly higher vegetable servings at 36 mo compared with the control group (P < 0.05). Energy intake from fat was significantly lower in the intervention group at 12 and 36 mo. The intervention group had significantly higher consumption of beta-carotene, alpha-carotene, lutein and beta-cryptoxanthin at 12 mo (P < 0.05). beta-Carotene, alpha-carotene and lutein intakes also were significantly higher at 36 mo (P < 0.05). At 36 mo, the intervention group had significantly higher plasma concentrations of alpha-carotene and beta-carotene compared with the control group. Repeated-measures ANOVA revealed that the intervention group had significantly increased (P < 0.05 with Bonferroni correction) plasma beta-carotene, alpha-carotene, lutein and lycopene concentrations at 12 and 36 mo compared with baseline. Baseline carotenoid concentrations were significantly inversely predictive (P < 0.05) of plasma carotenoid change. In addition, change in body mass index (BMI) and plasma cholesterol concentrations were predictive of plasma carotenoid change from baseline to 3 y. Results of this study demonstrate that change in plasma carotenoid concentrations is associated with change in BMI, change in plasma cholesterol and baseline carotenoid concentrations. Plasma carotenoid response can be an indicator of long-term high vegetable intake for women at risk of breast cancer recurrence.  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