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   466篇
  免费   25篇
  国内免费   19篇
耳鼻咽喉   1篇
儿科学   22篇
妇产科学   50篇
基础医学   64篇
口腔科学   8篇
临床医学   32篇
内科学   75篇
皮肤病学   10篇
神经病学   17篇
特种医学   47篇
外科学   39篇
综合类   29篇
预防医学   18篇
药学   52篇
中国医学   2篇
肿瘤学   44篇
  2023年   2篇
  2022年   3篇
  2021年   3篇
  2020年   4篇
  2019年   5篇
  2018年   5篇
  2017年   5篇
  2016年   9篇
  2015年   14篇
  2014年   25篇
  2013年   26篇
  2012年   26篇
  2011年   21篇
  2010年   23篇
  2009年   18篇
  2008年   16篇
  2007年   25篇
  2006年   25篇
  2005年   15篇
  2004年   9篇
  2003年   13篇
  2002年   6篇
  2001年   14篇
  2000年   8篇
  1999年   7篇
  1998年   21篇
  1997年   15篇
  1996年   10篇
  1995年   8篇
  1994年   12篇
  1993年   10篇
  1992年   2篇
  1991年   6篇
  1990年   8篇
  1989年   8篇
  1988年   8篇
  1987年   4篇
  1986年   4篇
  1985年   8篇
  1984年   7篇
  1983年   8篇
  1982年   6篇
  1981年   5篇
  1979年   8篇
  1978年   3篇
  1977年   7篇
  1974年   3篇
  1972年   2篇
  1971年   4篇
  1970年   4篇
排序方式: 共有510条查询结果,搜索用时 15 毫秒
11.
The amino acid intermediate homocysteine (Hcy) is formed during the metabolism of methionine to cysteine. Hyperhomocysteinemia (HHcy) is recognized as an independent risk factor for coronary atherosclerosis. The circulating levels of total Hcy (tHcy) can increase due to intake of foods rich in methionine or deficiencies of vitamins such as folate, pyridoxine and cyanocobalamin, which are required for the metabolism of Hcy. In addition, mutations in the genes coding for Hcy metabolizing enzymes can contribute to an increase in tHcy levels. Clinical and epidemiological studies have shown that an elevated level of tHcy measured in serum or plasma is a strong predictor of cardiovascular disease risk, which appears to be greatest in patients who have HHcy following a methionine load. Intimal hyperplasia (IH) (intima/media [I/M] ratio) is the universal response of a vessel to injury and may result in vasoconstriction when left unattended. The effect of dietary HHcy on balloon catheter-injured carotid artery and its modulation (if any) by the peroxisome proliferator-activated receptor agonist gamma rosiglitazone was evaluated in 12-week-old female Sprague-Dawley rats fed either a control diet or a diet containing 1% L-methionine. Once the rats were established on the diet, the group that was fed 1% L-methionine was further subdivided and either given an aqueous preparation of 3 mg/kg/day rosiglitazone or the vehicle via oral gavage for one week. This was followed by surgically injuring the left carotid artery using a Maverick Over-The-Wire catheter (2.0 mm × 20 mm, 3.2F; Boston Scientific, USA). The rats were continued on their respective diets and drug regimen for 21 days postsurgery. On day 22 of the procedure, the rats were sacrificed for collection of blood, the carotid arteries and liver for biochemical and histological evaluation. Compared with controls there was a significant increase in both tHcy levels and I/M ratio in the rats fed 1% L-methionine (5.4±0.28 μM versus 32.8±3.01 μM, P<0.002; and 0.175±0.05 versus 1.05±0.23, P<0.005, respectively). The effect of rosiglitazone in rats fed the control diet was not prominent. On the other hand, administration of rosiglitazone to the rats on the 1% L-methionine diet significantly reduced the levels of serum tHcy (16.6±2.1 μM versus 32.8±3.01 μM, P<0.001); however, the tHcy levels remained significantly elevated compared with animals on the control diet (P<0.002). The group receiving the L-methionine diet plus rosiglitazone had an inhibition in the development of IH compared with those receiving the L-methionine diet alone (I/M of 0.278±0.041 versus 1.05±0.23, P<0.01). Moreover, the development of IH in the group receiving the L-methionine diet plus rosiglitazone treatment was not significantly different from that observed in the group on the control diet without rosiglitazone (0.278±0.041 versus 0.175±0.05, respectively). These findings may have important implications in deciphering the molecular mechanisms involved in the augmentation of IH in HHcy and modulation of this process by rosiglitazone.  相似文献   
12.
Bilateral luteomas of pregnancy in a patient with diabetes   总被引:1,自引:0,他引:1  
A patient with diabetes and luteomas of the ovaries demonstrated a significant and progressive rise in the serum levels of androstenedione and testosterone during pregnancy. The levels of these hormones were also elevated in cord blood and ovarian fluid. The increased insulin requirement to maintain euglycemia was observed at an earlier date in this pregnancy than in her previous pregnancy.  相似文献   
13.
Recombinant bovine adenovirus is being developed as a live vector for animal vaccination and for human gene therapy. In this study, two replication-competent bovine adenovirus 3 (BAV-3) recombinants (BAV331 and BAV338) expressing bovine viral diarrhea virus (BVDV) glycoprotein E2 in the early region 3 (E3) of BAV-3 were constructed. Recombinant BAV331 contains chemically synthesized E2 gene (nucleotides modified to remove internal cryptic splice sites) under the control of BAV-3 E3/major late promoter (MLP), while recombinant BAV338 contains original E2 gene under the control of human cytomegalovirus immediate early promoter. Since E2, a class I membrane glycoprotein, does not contain its own signal peptide sequence at the 5' end, the bovine herpesvirus 1 (BHV-1) glycoprotein D signal sequence was fused in frame to the E2 open reading frame (ORF) for proper processing of the E2 glycoprotein in both the recombinant viruses. Recombinant E2 protein expressed by BAV331 and BAV338 recombinant viruses was recognized by E2-specific monoclonal antibodies as a 53-kDa protein, which also formed dimer with an apparent molecular weight of 94 kDa. Insertion of an E2-expression cassette in the E3 region did not effect the replication of recombinant BAV-3s. Intranasal immunization of cotton rats with these recombinant viruses generated E2-specific IgA and IgG responses at the mucosal surfaces and in the serum. In summary, these results show that the pestivirus glycoprotein can be expressed efficiently by BAV-3. In addition, mucosal immunization with replication-competent recombinant bovine adenovirus 3 can induce a specific immune response against the expressed antigen.  相似文献   
14.

Objective

Mycobacterial infections of the genital tract have been implicated in the etiology of female infertility. The correlation of endometrial TB PCR with laparoscopic and hysteroscopic features in patients with infertility was evaluated.

Methods

Women suffering from infertility and undergoing diagnostic laparoscopic and hysteroscopic examination were included. Endometrial specimens were assayed by Nested PCR for mycobacterium complex and the results were then retrospectively correlated with laparoscopic and hysteroscopic features.

Results

Positive TB PCR was observed in 32.18% (n=56) women. Out of these 56 patients, 48 had endoscopic abnormalities suggestive of tuberculosis (TB) and rest 8did not reveal any endoscopic abnormalities. However, of 174 patients 139 had endoscopic abnormalities with positive TB PCR in only 48. Sensitivity and specificity of endoscopic evaluation was 85.71 and 22.8%, respectively. The presence of periovarian adhesions, cornual block, tubal beading, tubercles, intrauterine adhesions, and ostial fibrosis had very strong association with positive TB PCR. Total predictive value of endoscopic evaluation in diagnosis of genital TB was 42.52%.

Conclusion

This study highlights that endoscopic evaluation is an important diagnostic tool, but can neither confirm nor exclude genital TB. Endometrial TB PCR may have to be routinely resorted to make a definite diagnosis of mycobacterial infection in endemic areas.  相似文献   
15.
These guidelines, written for clinicians, contains evidence-based recommendations for the prevention of hospital acquired infections Hospital acquired infections are a major cause of mortality and morbidity and provide challenge to clinicians. Measures of infection control include identifying patients at risk of nosocomial infections, observing hand hygiene, following standard precautions to reduce transmission and strategies to reduce VAP, CR-BSI, CAUTI. Environmental factors and architectural lay out also need to be emphasized upon. Infection prevention in special subsets of patients - burns patients, include identifying sources of organism, identification of organisms, isolation if required, antibiotic prophylaxis to be used selectively, early removal of necrotic tissue, prevention of tetanus, early nutrition and surveillance. Immunodeficient and Transplant recipients are at a higher risk of opportunistic infections. The post tranplant timetable is divided into three time periods for determining risk of infections. Room ventilation, cleaning and decontamination, protective clothing with care regarding food requires special consideration. Monitoring and Surveillance are prioritized depending upon the needs. Designated infection control teams should supervise the process and help in collection and compilation of data. Antibiotic Stewardship Recommendations include constituting a team, close coordination between teams, audit, formulary restriction, de-escalation, optimizing dosing, active use of information technology among other measure. The recommendations in these guidelines are intended to support, and not replace, good clinical judgment. The recommendations are rated by a letter that indicates the strength of the recommendation and a Roman numeral that indicates the quality of evidence supporting the recommendation, so that readers can ascertain how best to apply the recommendations in their practice environments.  相似文献   
16.
17.
18.
Fetal heart rate monitoring was first used as a clinical tool for the assessment of fetal danger and well-being. In the past decade, basic research has demonstrated the physiologic events associated with most heart rate changes. This review has demonstrated that study and semiquantification of the five analyzable features of an FHR recording can provide a strong reassurance of fetal health. The method has not proven as predictable for defining fetal disease, so additional parameters are needed to define clearly the significance of an abnormal FHR tracing.  相似文献   
19.
Glycosylated hemoglobin and blood sugar levels in the fasting state and two hours after oral 100 g glucose load were measured in 180 patients. Glycosylated hemoglobin was measured by cation exchange column chromatography, and blood sugar was measured by hexokinase reaction. Patients with an elevated postprandial and/or fasting blood sugar level (positive screen) subsequently underwent three-hour glucose tolerance test. The mean value of glycosylated hemoglobin in patients with a negative screen and normal hemoglobin was 6.17 +/- 0.61%; and the value for glycosylated hemoglobin in patients with class A diabetes and normal hemoglobin electrophoresis was 6.85 +/- 0.73% (P less than .001). A glycosylated hemoglobin value greater than 6.78 (mean + 1 SD) was considered elevated. Glycosylated hemoglobin values were elevated in 21 of 33 patients with gestational diabetes and in 27 of 147 patients with normal blood sugar levels. The sensitivity and specificity of glycosylated hemoglobin for the diagnosis of gestational diabetes were 63.6 and 81.6%, respectively. Fifty percent of patients with an initially elevated glycosylated hemoglobin value delivered macrosomic infants, whereas no patient with a normal glycosylated hemoglobin value had a macrosomic infant. An elevated glycosylated hemoglobin value may alert the obstetrician of a potentially elevated mean blood sugar level and may warrant aggressive management of gestational diabetes.  相似文献   
20.

Background  

The objective of this study was to demonstrate the use of an association rule mining approach to discover associations between selected socioeconomic variables and the four most leading causes of cancer mortality in the United States. An association rule mining algorithm was applied to extract associations between the 1988–1992 cancer mortality rates for colorectal, lung, breast, and prostate cancers defined at the Health Service Area level and selected socioeconomic variables from the 1990 United States census. Geographic information system technology was used to integrate these data which were defined at different spatial resolutions, and to visualize and analyze the results from the association rule mining process.  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