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   896篇
  免费   23篇
  国内免费   10篇
耳鼻咽喉   1篇
儿科学   35篇
妇产科学   7篇
基础医学   62篇
口腔科学   10篇
临床医学   63篇
内科学   106篇
皮肤病学   29篇
神经病学   5篇
特种医学   98篇
外科学   105篇
综合类   259篇
预防医学   68篇
眼科学   4篇
药学   31篇
肿瘤学   46篇
  2023年   1篇
  2022年   3篇
  2021年   7篇
  2020年   3篇
  2019年   5篇
  2018年   7篇
  2017年   7篇
  2016年   5篇
  2015年   29篇
  2014年   13篇
  2013年   19篇
  2012年   21篇
  2011年   14篇
  2010年   48篇
  2009年   47篇
  2008年   35篇
  2007年   46篇
  2006年   60篇
  2005年   42篇
  2004年   58篇
  2003年   29篇
  2002年   26篇
  2001年   18篇
  2000年   19篇
  1999年   31篇
  1998年   42篇
  1997年   53篇
  1996年   55篇
  1995年   34篇
  1994年   30篇
  1993年   9篇
  1992年   9篇
  1991年   6篇
  1990年   7篇
  1989年   7篇
  1988年   15篇
  1987年   9篇
  1986年   10篇
  1985年   7篇
  1984年   11篇
  1983年   4篇
  1982年   7篇
  1981年   6篇
  1980年   4篇
  1978年   3篇
  1977年   4篇
  1976年   2篇
  1975年   2篇
排序方式: 共有929条查询结果,搜索用时 15 毫秒
101.
Shunt surgery is considered to be the treatment of choice in patients with non-cirrhotic portal hypertension. There is little data on the effect of side-to-side lieno-renal (SSLR) shunt on oesophageal variceal size, splenic size and splenic pulp pressure (SPP) in patients with non-cirrhotic portal hypertension. We evaluated pre- and postoperatively endoscopic grading of varices, splenic size and SPP for predicting shunt patency in 86 patients with non-cirrhotic portal hypertension: 56 with extrahepatic portal venous obstruction (EHPVO) and 30 with non-cirrhotic portal fibrosis (NCPF). The EHPVO patients with patent shunts (n= 47) showed significant reduction in SPP (pre-operative 43.56±7.9 vs postoperative 29.96±7.7 cm of saline), splenic size (6.5±2.8 vs 4.00±2.6 cm below costal margin) and varices grades (2.96±0.5 vs 0.92±0.8). Patients with blocked shunt (n= 9) did not show significant reduction in SPP and varices grades. However, there was reduction in spleen size (8.6±3.0 vs 6.3±4.3). In the NCPF group, 28 had patent shunts and showed significant reduction in SPP (46.3±13.5 vs 33.8±7.6 cm of saline), splenic size (9.1±3.3 vs 6.8±4.6 cm below costal margin) and varices grades (2.8±0.7 vs 1.05±0.96). As only two patients with NCPF had blocked shunts, no statistical comparison between patients with patent and patients with blocked shunts could be done. In conclusion, following SSLR, there is a significant reduction in SPP and varices grades in patients with patent shunts. Endoscopic grading of varices can be used to predict shunt patency. However, spleen size is not a good criteria for predicting shunt patency.  相似文献   
102.
Rowell's syndrome (RS) is a rare presentation of lupus erythematosus (LE) with erythema multiforme‐like lesions associated with antinuclear, anti‐La (SS‐B)/anti‐Ro (SS‐A) antibodies and rheumatoid factor (RF) positivity. This syndrome is suggested to be a different variant of cutaneous lupus erythematosus by some authors in literature. Here we present a 64‐year‐old woman with LE and a 51‐year‐old woman with LE and Sjögren syndrome (SS) who had erythema multiforme‐like eruptions and discuss the coexistence of lupus erythematosus and erythema multiforme.  相似文献   
103.

Background

A study was conducted to evaluate a system of standardizing the oxygen concentration inside the oxygen hood and to develop guidelines for controlled FiO2 administration by changing size of the hood, lid position on the hood and the oxygen flow rate, without an oxygen analyzer. The effect of low flow rates on carbon dioxide (CO2) retention was also studied.

Method

A dummy patient and thirty neonates, requiring oxygen to be delivered through head box, constituted the material for the study group. Oxygen content in the head box was measured using a standard oxygen analyzer while the size of head box, flow rate and lid position were changed independently and in combination. The head boxes were tested on a dummy patient. These results were analyzed, and applied to thirty neonates requiring oxygen therapy using a head box.

Result

Volume of headbox had an inverse relation with the oxygen concentration inside the headbox and smaller sized headbox achieved more predictable oxygen concentration at all flow rates. Maximum difference in oxygen concentration by varying the lid position was seen in the large headbox. Keeping the variables constant, oxygen concentration was significantly lower in babies as compared to dummy. No significant CO2 retention was found at a flow rate of four litres per minute (lpm) in small and three lpm in a medium and large head box respectively, while lower flow rates were associated with CO2 retention.

Conclusion

It is possible to predict the oxygen concentration inside the head box without the use of oxygen analyzer. Larger head box and higher lid position, results in lower oxygen concentration, at a given oxygen flow rate. Oxygen concentration achieved in babies is lesser than the concentration achieved in a dummy. Flow rates of less than four lpm in small and three lpm in medium and large sized head boxes are associated with CO2 retention. These results are not applicable to infants weighing less than 2 kg.Key Words: Neonates, Oxygen therapy, Oxygen hood, Oxygen concentration, Oxygen analyzer  相似文献   
104.
105.
A hospital-based case-control study was carried out to clarify the characteristics of mucoid presentation of acute enterocolitis in children. One hundred sixty-eight cases of acute mucoid enterocolitis (study population) were compared with 200 cases of watery diarrhoea and 118 cases of blood dysentery (control groups) on the basis of clinical characteristics and findings on stool examination. Study and control groups were comparable with respect to age, body weight and nutritional status. There was no significant difference in clinical characteristics (duration of diarrhoea, stool frequency, presence of vomiting, fever and dehydration) between patients suffering from mucoid enterocolitis and blood dysentery. However, watery diarrhoea patients had significantly high frequencies of vomiting (p = 0.00001) and dehydration (p  相似文献   
106.
107.
A modified Western blot (WB) that includes both shared (r21e) and unique recombinant envelope proteins from human T-lymphotropic virus (HTLV) type I (rgp46I) and type II (rgp46II) was compared to conventional HTLV serologic tests in 379 United States blood donors and individuals residing in diverse geographic regions, and the specimens were categorized as positive (n = 158), indeterminate (n = 158), or negative (n = 63) for HTLV infection. Of the 158 HTLV-I/II-positive specimens (66 requiring radioimmunoprecipitation assay [RIPA] for confirmation), 156 reacted concordantly with r21e, gag, and either rgp46I or rgp46II, thus eliminating the need for RIPA in all but two specimens and yielding a test sensitivity of 98.7 percent. Of the 158 indeterminate and 63 negative specimens, none reacted with r21e and rgp46I or rgp46II, yielding a test specificity of 100 percent. Furthermore, analysis of an additional 184 consecutive specimens from a retrovirology reference laboratory demonstrated that the modified WB correctly identified 27 of 28 HTLV-I specimens and all 13 HTLV-II specimens, with a test sensitivity of 97.6 percent. None of specimens that were indeterminate or nonreactive in conventional WB and/or RIPA and none of the screening enzyme immunoassay-negative specimens reacted with r21e and either rgp46I or rgp46II, for a test specificity of 100 percent. Thus, the modified WB appears to be highly sensitive and specific for simultaneous detection and discrimination of HTLV-I from HTLV-II and has the advantage of being a one-step assay that is easily performed in all types of laboratory settings and allows rapid, reliable, and standardized testing for HTLV-I/II infection.  相似文献   
108.
In a prospective survey of infants born in a single maternity unit, asymptomatic faecal colonisation by Clostridium difficile occurred in 31 (47%) of 66 babies who provided a faecal sample during week one of life and at age 14 and 28 days, and in 46 (30.7%) of the total of 150 babies for whom at least one faecal sample was obtained during the month of study. There was no evidence for acquisition of the organism from the mother during delivery and colonisation was unrelated to the means of delivery, infant sex, means of feeding, duration of hospital stay, or antibiotic treatment. New colonisation occurred throughout the month of the study and further evidence for environmental acquisition was obtained by the finding of a similar strain of C difficile in 7 babies from one ward together with positive environmental cultures. Colonisation was frequently transient and occasionally intermittent; most infants kept the same strain during their period of carriage. Twenty two (47.8%) babies colonised by C difficile had low titres of cytopathic faecal toxin but none had symptomatic diarrhoea or features of necrotizing enterocolitis. The in vitro toxigenic potential of 57 toxigenic isolates from 36 babies was low and 12 babies carried non-toxigenic strains. Transient colonisation by C difficile in early life is almost certainly more common than is generally recognized and the neonate provides an important reservoir of potential infection.  相似文献   
109.
OBJECTIVE: To evaluate the accuracy of a rapid assay that wasdeveloped to detect Helicobacter pylori antigen in the stool,using the principle of immunochromatography, in the Chinese population. METHODS: Eligible patients without prior treatment of H.pylori were recruited. An in‐house rapid urease test (RUT) andhistology were used as the gold standard. The results of the rapidstool antigen test were compared with the gold standard. RESULTS: Valid rapid stool antigen test results for interpretationwere obtained from 94 consecutive patients (mean age: 52.5, range:22?82 years). Sensitivity, specificity, positive predictivevalue, negative predictive value and accuracy were, respectively, 77.5%,87.0%, 81.6%, 83.9% and 83.0%.The test was easy to perform and results were available within 15 min. CONCLUSION: The rapid stool antigen test using immunochromatography accuratelydiagnoses H. pylori infection in Chinese patients.  相似文献   
110.
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