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   3002篇
  免费   201篇
  国内免费   33篇
耳鼻咽喉   22篇
儿科学   127篇
妇产科学   68篇
基础医学   323篇
口腔科学   52篇
临床医学   337篇
内科学   652篇
皮肤病学   65篇
神经病学   163篇
特种医学   276篇
外科学   307篇
综合类   44篇
预防医学   242篇
眼科学   52篇
药学   166篇
中国医学   27篇
肿瘤学   313篇
  2024年   4篇
  2023年   31篇
  2022年   69篇
  2021年   175篇
  2020年   82篇
  2019年   146篇
  2018年   133篇
  2017年   88篇
  2016年   91篇
  2015年   89篇
  2014年   125篇
  2013年   120篇
  2012年   171篇
  2011年   175篇
  2010年   123篇
  2009年   100篇
  2008年   133篇
  2007年   121篇
  2006年   109篇
  2005年   104篇
  2004年   84篇
  2003年   103篇
  2002年   95篇
  2001年   34篇
  2000年   43篇
  1999年   39篇
  1998年   55篇
  1997年   62篇
  1996年   47篇
  1995年   31篇
  1994年   48篇
  1993年   28篇
  1992年   20篇
  1991年   22篇
  1990年   24篇
  1989年   42篇
  1988年   26篇
  1987年   32篇
  1986年   31篇
  1985年   18篇
  1984年   21篇
  1983年   13篇
  1982年   18篇
  1981年   28篇
  1980年   8篇
  1979年   10篇
  1978年   13篇
  1977年   13篇
  1976年   15篇
  1975年   11篇
排序方式: 共有3236条查询结果,搜索用时 15 毫秒
91.
92.
93.
IntroductionHistorically, it has been assumed that Intermediate Respiratory Care Units (IRCU) were efficient, because they saved costs by reducing the number of admissions to intensive care units (ICU), and effective, because they specialized in respiratory diseases.MethodsThe number of IRCU admissions and mortality rate, historically and in 2016, were evaluated. For 2016, the grouped Related Diagnostic Groups (DRGs) were also described, and the savings achieved under all budgetary headings by avoiding UCI stays were calculated. A multivariate analysis was performed to associate costs with mean weights and complexity, and multiple logistic regression was performed on all patients admitted from 2004 to 2017 to describe the variables associated with mortality in our unit.ResultsAn IRCU generates savings of €500,000/year by reducing length of ICU stay. Analysis of the 2016 cohort shows that costs correlate with mean weight and mortality, and consequently complexity. The multivariate logistic regression analysis of the 2004–2017 cohort found respiratory frequency, leukopenia, anemia, hyperkalemia, and acidosis to be the variables best associated with mortality. The area under the curve for the logistic model was 0.75.ConclusionThe IRCU analyzed in our study was efficient in terms of ‘avoided costs’ and savings associated with complexity. Our results suggest that IRCUs have a lower mortality rate than other similar units, and are therefore a safe environment for patients.  相似文献   
94.
95.
We performed a seroepidemiological study of anti-Helicobacter pylori IgG by a commercial enzyme immunoassay kit (Meridian Diagnostics, USA) in 509 serum samples from 314 randomly selected asymptomatic subjects from among the population, and grouped into children (n = 124), adolescents (n = 74) and adults (n = 116), and in 195 serum samples from subjects presenting clinical gastric symptoms, grouped into children (n = 38) and adults (n = 157). The cut-off value was redefined and set at OD450 = 0.050. The percentage of seropositive individuals was not significantly different between the two groups of adults studied (75.9% and 80.2%, respectively) (p < 0.05), suggesting a high degree of contact with the microorganism in this region.  相似文献   
96.
Study of nuclear diameters in non-Hodgkin's lymphomas   总被引:2,自引:5,他引:2       下载免费PDF全文
The mean maximum nuclear diameter (Dmax) in 21 cases of non-Hodgkin's lymphoma (NHL) has been determined, using the Reichert-Jung (Kontron) MOP-AMO3 user-controlled image analyser. Nuclear diameters of high-grade malignancy NHL were found to be considerably greater than those of low-grade malignancy lymphomas, although there was some overlap of their ranges. These findings confirm objectively subjective estimates of nuclear size in NHL. The relative usefulness of the user-controlled (interactive) image analyser for the measurement of nuclei in tissue sections is compared with that of a fully automatic machine.  相似文献   
97.
Oxidative stress plays an important role in the pathogenesis of neurodegenerative diseases, such as Parkinson's disease (PD). There are several methods to measure oxidative stress, being lipid peroxidation (LPO) one of the most frequently used. Endogenous plasma LPO was determined by a spectrofluorimetric method in fifty two patients with sporadic PD and in forty controls. To know the maximum capacity of lipids to peroxidate, LPO was also measured after co-incubation with Fe2+/H2O2 (exogenous LPO). All PD patients were taken L-dopa and the effect of this treatment on LPO levels was additionally studied. Urine catecholamines and their main metabolites were also analyzed, and their possible correlation to LPO statistically studied. Endogenous plasma LPO levels were 33% higher in PD group than in control group (P<0.001). Exogenous plasma or oxidizability was also higher in PD patients compared to controls (20%, P<0.05). The intake of L-dopa was negatively dose-related to endogenous and exogenous plasma LPO. In conclusion, plasma of PD patients has elevated levels of LPO and also is more prone to peroxidation than that in the control group. The results also suggest an antioxidant effect of L-dopa.  相似文献   
98.
99.
CTX-M-19 is a recently identified ceftazidime-hydrolyzing extended-spectrum beta-lactamase, which differs from the majority of CTX-M-type beta-lactamases that preferentially hydrolyze cefotaxime but not ceftazidime. To elucidate the mechanism of ceftazidime hydrolysis by CTX-M-19, the beta-lactam MICs of a CTX-M-19 producer, and the kinetic parameters of the enzyme were confirmed. We reconfirmed here that CTX-M-19 is also stable at a high enzyme concentration in the presence of bovine serum albumin (20 micro g/ml). Under this condition, we obtained more accurate kinetic parameters and determined that cefotaxime (k(cat)/K(m), 1.47 x 10(6) s(-1) M(-1)), cefoxitin (k(cat)/K(m), 62.2 s(-1) M(-1)), and aztreonam (k(cat)/K(m), 1.34 x 10(3) s(-1) M(-1)) are good substrates and that imipenem (k(+2)/K, 1.20 x 10(2) s(-1) M(-1)) is a poor substrate. However, CTX-M-18 and CTX-M-19 exhibited too high a K(m) value (2.7 to 5.6 mM) against ceftazidime to obtain their catalytic activity (k(cat)). Comparison of the MICs with the catalytic efficiency (k(cat)/K(m)) of these enzymes showed that some beta-lactams, including cefotaxime, ceftazidime, and aztreonam showed a similar correlation. Using the previously reported crystal structure of the Toho-1 beta-lactamase, which belongs to the CTX-M-type beta-lactamase group, we have suggested characteristic interactions between the enzymes and the beta-lactams ceftazidime, cefotaxime, and aztreonam by molecular modeling. Aminothiazole-bearing beta-lactams require a displacement of the aminothiazole moiety due to a severe steric interaction with the hydroxyl group of Ser167 in CTX-M-19, and the displacement affects the interaction between Ser130 and the acidic group such as carboxylate and sulfonate of beta-lactams.  相似文献   
100.
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