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   91206篇
  免费   5869篇
  国内免费   2508篇
耳鼻咽喉   575篇
儿科学   1527篇
妇产科学   1058篇
基础医学   7744篇
口腔科学   1950篇
临床医学   8903篇
内科学   10733篇
皮肤病学   1066篇
神经病学   6595篇
特种医学   2290篇
外国民族医学   8篇
外科学   8554篇
综合类   14593篇
现状与发展   5篇
一般理论   4篇
预防医学   8769篇
眼科学   1372篇
药学   11878篇
  124篇
中国医学   9392篇
肿瘤学   2443篇
  2024年   314篇
  2023年   1626篇
  2022年   2831篇
  2021年   3868篇
  2020年   3403篇
  2019年   3403篇
  2018年   3028篇
  2017年   2813篇
  2016年   2683篇
  2015年   2491篇
  2014年   5428篇
  2013年   5253篇
  2012年   4941篇
  2011年   6035篇
  2010年   5240篇
  2009年   4073篇
  2008年   3968篇
  2007年   4200篇
  2006年   3710篇
  2005年   3137篇
  2004年   2691篇
  2003年   2436篇
  2002年   1832篇
  2001年   1585篇
  2000年   1411篇
  1999年   1233篇
  1998年   1039篇
  1997年   1019篇
  1996年   886篇
  1995年   919篇
  1994年   860篇
  1993年   729篇
  1992年   689篇
  1991年   667篇
  1990年   647篇
  1989年   573篇
  1988年   561篇
  1987年   500篇
  1986年   504篇
  1985年   847篇
  1984年   784篇
  1983年   585篇
  1982年   698篇
  1981年   599篇
  1980年   572篇
  1979年   489篇
  1978年   384篇
  1977年   398篇
  1976年   295篇
  1975年   193篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
BACKGROUND: Sodium removal (NaR) may have a major impact on the survival of peritoneal dialysis patients. The dialysate/plasma sodium concentration ratio (D/P(Na)) is an indirect index of transcellular water transport by aquaporin channels, and thus of ultrafiltration. Sodium concentration can be assessed by means of flame photometry (F), and direct (D-ISE) or indirect ion-selective electrodes (I-ISE), but these methods have different properties. I-ISE is being used increasingly in clinical laboratories. The aim of this study was to evaluate NaR and D/P(Na) using the three different measurement methods. METHODS: We performed peritoneal equilibration tests (PETs) in 44 peritoneal dialysis patients and calculated the NaR. We also calculated D/P(Na) during the test; plasma and dialysate sodium concentrations were measured by F, D-ISE and I-ISE. RESULTS: NaR was lower (P<0.001) with D-ISE (69+/-29 mmol) than with F (81+/-29 mmol) or I-ISE (79+/-28 mmol). D/P(Na) was also lower at baseline (0.92+/-0.02 vs 0.95+/-0.02 and 0.95+/-0.02; P<0.001), after 60 min (0.87+/-0.03 vs 0.90+/-0.03 and 0.90+/-0.03; P<0.001) and at the end of PET (0.88+/-0.04 vs 0.92+/-0.04 and 0.92+/-0.04; P<0.001) when measured by D-ISE in comparison with F and I-ISE, respectively. CONCLUSIONS: NaR and D/P(Na) were lower when measured by the D-ISE method compared with the F and I-ISE methods. NaR and D/P(Na) were similar when measured by F or I-ISE. I-ISE can be used reliably in the evaluation of NaR and D/P(Na) in everyday clinical practice of peritoneal dialysis.  相似文献   
82.
Two topical corticosteroids, budesonide (BUD) and beclomethasone dipropionate (BDP), both administered as suspensions in water, were investigated in healthy volunteers regarding influence on cortisol in plasma and urine (U-cortisol) after nasal application. In the first study, single doses of 200, 400, and 800 μg of BDP and BUD were given at 10:00 pm. In the second study, 100, 200, and 400 μg were given mornings and evenings for 4 days. In the single-dose study, none of the drugs or doses showed any significant influence on cortisol in plasma. However, U-cortisol decreased significantly after BUD 400 and 800 μg. In the multidose study, U-cortisol values were significantly reduced after all doses of BUD and the highest dose of BDP. The compounds tested showed different ability to cause measurable systemic effects after nasal application. The clinical implication is that the prescriber, when choosing a compound, should take the application site into consideration and should also be encouraged to find the lowest effective dose.  相似文献   
83.
The intrauterine position occupied by a rodent fetus influences the amount of testosterone to which it is exposed before birth. Animals that are gestated between two male fetuses (2M) are exposed to higher circulating levels of testosterone than are animals positioned between two female fetuses (2F) and there are reliable differences in the reproductive physiology and behavior of 2M and 2F animals when adult. To determine whether intrauterine position modifies development of the central nervous system, we examined the sexually dimorphic spinal nucleus of the bulbocavernosus (SNB) in male and female gerbils from known intrauterine positions. We found that adult 2M female gerbils had 16% more SNB motoneurons than did 2F females. 2M males did not differ from 2F males in SNB motoneuron number, but the bulbocavernosus muscle, which is innervated by SNB motoneurons, was approximately 50% larger in 2M than in 2F males. These data indicate that intrauterine position can influence the morphology of the sexually dimorphic SNB neuromuscular system.  相似文献   
84.
Dysphoric Rumination Impairs Concentration on Academic Tasks   总被引:3,自引:0,他引:3  
Three studies investigated the effects of dysphoric rumination on concentration during 3 academic tasks—reading a passage from the GRE (Study 1), watching a videotaped lecture (Study 2), and proofreading written text (Study 3). Before performing these tasks, dysphoric and nondysphoric students were induced either to ruminate about themselves or to distract themselves by focusing on neutral images (all three studies) or by planning an event (Study 1). The results supported our hypothesis that dysphoric rumination, relative to distraction, would impair students' concentration. In all 3 studies, dysphoric ruminators reported difficulty concentrating, as well as interfering thoughts, during the relevant academic tasks. Furthermore, dysphoric ruminators were slower than dysphoric distractors in completing the tasks—specifically, reading the GRE passage (Study 1) and answering lecture comprehension questions (Study 2). In addition, dysphoric participants who ruminated showed impaired reading strategies (Study 1), reduced comprehension of academic material (Study 2), and poor proofreading performance (Study 3). These findings suggest that, in addition to its documented adverse effects on mood, thinking, and problem-solving, self-focused rumination interferes with instrumental behavior. Implications for social relationships and job performance are discussed.  相似文献   
85.
活性炭纤维在地方性氟中毒方面的应用展望   总被引:1,自引:0,他引:1  
曹守仁 《卫生研究》1994,23(2):77-79
介绍了活性炭纤维(ACFs)的制造,特性及其应用。它具有优异的结耕与性能特征。含碳量高,比表面积大,微孔丰富,从而吸附力强,而且活性炭纤维还可制成纱、布、毡等形状,它可用于去除燃煤氟中毒区室内空气中氟化氢、二氧化硫、氧化氮、氨等污染物,利用它的高吸附性能还可较好的去除饮水中的氟化物及其他有害物质。活性炭纤维是一种新型高效吸附材料。在氟中毒防治方面有广阔的前途。  相似文献   
86.
Both systemic and local therapy, for conditions of the breast and unrelated to it, may produce manuno-graphic changes. Some of these are characteristic, such as the pattern of scarring seen in reduction mammo-plasty. In many other instances, however, the changes produced overlap features commonly seen in malignancy. A knowledge of the timing, natural history and spectrum of these changes will aid mammographic interpretation.  相似文献   
87.
We report satisfactory results with a new operative treatment, conducted via an extensive anterolateral approach, involving 360 degree circumferential capsulotomy, for residual subluxation in congenital dislocation of the hip (CDH). Long-term radiographic results of this procedure (group A) were compared retrospectively with the results of partial capsulotomy (group B), which preserved the posteroinferior joint capsule. The mean center edge angle in group A (22.5°) was greater than that in group B (16.0°). Satisfactory results were achieved in 11 of 15 hips (73%) (Severin class I or II) in group A, and in 5 of 12 hips (42%) in group B. These results suggest that whole circumferential capsulotomy can remove obstacles to complete reduction, and that acetabular development can be expected in hips reduced by the procedure, without the performance of innominate osteotomy. We believe that our technique is a useful alternative for the treatment of residual subluxation in CDH.  相似文献   
88.
本文报道了1995年春对九洲港货运港区的鼠密度和灭鼠效果调查,结果鼠密度投药后(4.1%)比投药前(24.6%)有明显下降,灭鼠率达83.3%;根据九洲港货运港区鼠患情况,提出防鼠灭鼠建议。  相似文献   
89.
本文在25例(50侧)胎尸标本上对旋股外侧动脉分布、分支类型、管径及其临床应用解剖进行了详细的观察和讨论分析。以期对临床应用有所帮助。  相似文献   
90.
Although the adverse effect on pregnancy outcomes at high levels of lead exposure in the workplace has been recognized for years, there is uncertainty regarding the impact of exposure at the lower community exposure levels commonly encountered today. This review summarizes the epidemiologic literature and discusses pertinent methodologic issues and possible sources of interstudy variation. The authors conclude that prenatal lead exposure is unlikely to increase the risk of premature membrane rupture but does appear to increase the risk of preterm delivery. Whether prenatal lead exposure decreases gestational age in terms of infants is unclear. Prenatal lead exposure also appears to be associated with reduced birth weight, but results vary in relation to study design and degree of control for confounding. Adjustment for gestational age, a possible confounder of the birth weight-lead exposure association, did not yield clearer results.  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