首页 | 官方网站   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   1460篇
  免费   118篇
  国内免费   5篇
医药卫生   1583篇
  2023年   15篇
  2022年   15篇
  2021年   59篇
  2020年   28篇
  2019年   38篇
  2018年   60篇
  2017年   33篇
  2016年   54篇
  2015年   48篇
  2014年   64篇
  2013年   71篇
  2012年   95篇
  2011年   94篇
  2010年   58篇
  2009年   32篇
  2008年   71篇
  2007年   77篇
  2006年   83篇
  2005年   75篇
  2004年   92篇
  2003年   74篇
  2002年   63篇
  2001年   33篇
  2000年   33篇
  1999年   25篇
  1998年   16篇
  1997年   9篇
  1996年   4篇
  1995年   7篇
  1994年   12篇
  1993年   9篇
  1992年   14篇
  1991年   12篇
  1990年   13篇
  1989年   21篇
  1988年   13篇
  1987年   15篇
  1986年   11篇
  1985年   6篇
  1984年   6篇
  1983年   6篇
  1979年   2篇
  1975年   1篇
  1974年   4篇
  1972年   1篇
  1971年   2篇
  1969年   2篇
  1968年   1篇
  1967年   1篇
  1966年   2篇
排序方式: 共有1583条查询结果,搜索用时 15 毫秒
51.
Although the efficacy of hepatitis B vaccines in patients undergoing chronic hemodialysis (HD) treatment has been documented, the persistence of immunity in this population remains largely unknown. In this study we evaluated the persistence of hepatitis B vaccine immunity in HD patients. We followed 37 hepatitis B vaccinated HD patients (following a four-dose vaccination schedule of 40 mug injections intramuscularly in the deltoid muscle at 0, 1, 2, and 6 months) for up to one year to evaluate the persistence of immunity (as indicated by serum levels of hepatitis B surface antibody (anti-HBs) equal to or higher than 10 IU/L). One year after vaccination, 18.9% of patients had lost their anti-HBs (transient responders), while 81.1% still had detectable antibodies in the serum (persistent responders). From 81.1% of persistent responders 11.5% and 88.5% were weak and high responders, respectively. There was no significant difference between persistent and transient responders regarding age, sex, or nutritional factors. We did not find any factors that related to maintaining protective levels of anti-HBs in HD patients. It seems that an antibody titer above 100 IU/L following vaccination is necessary in order to maintain that level of antibody one year later.  相似文献   
52.
Methicillin-resistant Staphylococcus aureus (MRSA) represents a serious threat to the health of hospitalized patients. Attempts to reduce the spread of MRSA have largely depended on hospital hygiene and patient isolation. These measures have met with mixed success: although some countries have almost eliminated MRSA or remained largely free of the organism, others have seen substantial increases despite rigorous control policies. We use a mathematical model to show how these increases can be explained by considering both hospital and community reservoirs of MRSA colonization. We show how the timing of the intervention, the level of resource provision, and chance combine to determine whether control measures succeed or fail. We find that even control measures able to repeatedly prevent sustained outbreaks in the short-term can result in long-term control failure resulting from gradual increases in the community reservoir. If resources do not scale with MRSA prevalence, isolation policies can fail "catastrophically."  相似文献   
53.
54.
Objective: To determine epidemiologic and metabolic characteristics of renal stone in the northern Iran. Methods: We prospectively analyzed demographic, clinical and metabolic findings in children less than 16 years old with renal stone revealed by ultrasonography from September 2003 to May 2012. Evaluations included serum and urine measurement of main elements predisposing patients to stone formation. Findings : 271 children (160 males) aged 2 months to 16-years (mean 30 months) were evaluated. 91 (33.6%) had a positive family history, abdominal discomfort (18.8%), UTI (11.8%) and hematuria (11.4%) were main presenting features. 45 children were diagnosed accidentally without any specific compliant. Nearly all (99%) stones lay in kidney., 35.1% had metabolic, 10% infective and 4.1% obstructive trends, 110 children had no definable etiology. Hypercalciuria (25.5%) hyperoxaluria (18.4%) and hypocitraturia (18.1%) were more frequent than uricosuria (8.5%) and cystinuria (3.1%) Conclusion: Metabolic derangement plays significant role in stone formation in our area. Patients should be carefully evaluated considering this point of view.Key Words: Nephrolithiasis, Kidney Stone, Hypercalciuria, Hyperoxaluria, Cystinuria, Hypocitraturia  相似文献   
55.

Objective

To determine difference in the levels of circulating inactive ghrelin between undernourished and healthy children.

Methods

The present cross-sectional study was conducted in undernourished children from southwestern Iran, from July 2011 through July 2012. Postprandial inactive ghrelin levels were measured in 40 undernourished children and sex- and age-matched healthy controls by enzyme immunoassay.

Results

The levels of postprandial inactive ghrelin were considerably lower in undernourished compared to the healthy children (6.4 vs. 12.9, P?vs. 7.1, P?=?0.032).

Conclusions

Thus, the levels of inactive ghrelin was found to be low in undernourished children compared to healthy children. Early loss of appetite might be a result of low circulating inactive ghrelin levels in the postprandial state in undernourished children.  相似文献   
56.

Background:

Liver enzymes elevations (LEE) can be observed after kidney transplantation due to multifactorial causes.

Objectives:

We performed a retrospective study on 1589 kidney transplants, 971 male and 618 female, who were hepatitis B surface antigen (HBsAg) and hepatitis C virus-antibody (HCV Ab) negative, and had no other liver diseases, to detect the prevalence of LEE and its risk factors in these patients between May 2008 and May 2010.

Patients and methods:

Liver enzymes and other biochemical parameters were measured in all recipients. Patients were divided into three groups, according to laboratory test time since transplantation: Group I, less than 3 months, Group II, 4 - 12 months after transplantation, and Group III, more than one year post-transplantation.

Results:

The highest LEE was more frequent in older patients (P < 0.001) and male individuals (P < 0.001). Aspartate aminotransferase (AST) and alanine aminotransferase (ALT) levels were higher in patients who received kidneys from deceased donors (10.4% and 23.8%, respectively) as compared to living donor transplants (5.6% and 14.8%, respectively) (P < 0.001). The elevation of ALT was the liver enzyme abnormality after kidney transplantation with the highest prevalence (34.3%). The levels of ALT and AST were significantly elevated within the first 3 months after transplantation, followed by the 4-12 months period (P < 0.001). There was a reverse correlation between liver enzyme levels and renal allograft function in both univariate and linear regression analyses. This correlation increased over time. There was also a significant relation between cyclosporine blood levels and liver enzyme values in the univariate analysis. However, this relationship was attenuated over time. Elevated liver enzymes also correlated with anemia.

Conclusions:

The LEE is a common finding among kidney transplant recipients. Serial monitoring of aminotransferases, particularly ALT, should be performed in all patients after kidney transplantation.  相似文献   
57.

Aims/hypothesis  

Type 2 diabetes is associated with greater relative risk of CHD in women than in men, which is not fully explained by conventional cardiovascular risk factors. We assessed whether cardiovascular risk factors including more novel factors such as markers of insulin resistance, inflammation, activated coagulation and endothelial dysfunction differ more between diabetic and non-diabetic women than between diabetic and non-diabetic men, and the role of insulin resistance.  相似文献   
58.
Protein disulfide isomerase (PDI), an endoplasmic reticulum chaperone protein, catalyzes disulfide bond breakage, formation, and rearrangement. The effect of PDI inhibition on ovarian cancer progression is not yet clear, and there is a need for potent, selective, and safe small-molecule inhibitors of PDI. Here, we report a class of propynoic acid carbamoyl methyl amides (PACMAs) that are active against a panel of human ovarian cancer cell lines. Using fluorescent derivatives, 2D gel electrophoresis, and MS, we established that PACMA 31, one of the most active analogs, acts as an irreversible small-molecule inhibitor of PDI, forming a covalent bond with the active site cysteines of PDI. We also showed that PDI activity is essential for the survival and proliferation of human ovarian cancer cells. In vivo, PACMA 31 showed tumor targeting ability and significantly suppressed ovarian tumor growth without causing toxicity to normal tissues. These irreversible small-molecule PDI inhibitors represent an important approach for the development of targeted anticancer agents for ovarian cancer therapy, and they can also serve as useful probes for investigating the biology of PDI-implicated pathways.  相似文献   
59.
The objective of this study was to determine the Salmonella prevalence, the serotypes involved, and antimicrobial susceptibility patterns of Salmonella isolates recovered from fish, shrimp, lobster, and crab in Iran. A total of 384 samples of fish, shrimp, lobster, and crab were collected in three provinces along the Persian Gulf in the south coast of Iran. Samples were collected at the end of each month from September 2009 to May 2011. All samples were evaluated for the presence of Salmonella, stereotyped and tested for antimicrobial susceptibility. There was an overall Salmonella prevalence of 5%. Salmonella was isolated from a significantly larger number of fish (10.4%) than shrimp (1.8%; P?≤?0.05). No Salmonella was isolated from lobster and crab samples. Salmonella isolates recovered from fish and shrimp samples were of five different serotypes including Salmonella typhimurium, Salmonella enteritidis, Salmonel la typhi, Salmonella paratyphi B, and Salmonella newport. Susceptibilities of Salmonella isolates were determined for 12 antimicrobial drugs using the disk-diffusion method. Resistance to nalidixic acid was the most common finding (47.4%), followed by resistance to tetracycline (36.8%), streptomycin (15.8%), trimethoprim (15.8%), and ciprofloxacin (5.3%). To our best knowledge, this is the first study on prevalence of Salmonella in fish, shrimp, lobster, and crab and the first report on the isolation of Salmonella spp. from retail fish and shrimp in Iran.  相似文献   
60.
Milk is considered a nutritious food because it contains several important nutrients including proteins and vitamins. Conversely, it can be a vehicle for several pathogenic bacteria such as Staphylococcus aureus. The aim of the present study was to investigate the presence of classical enterotoxins of S. aureus in raw milk in Iran. For this purpose, from January 2011 to October 2011, a total of 88 raw milk samples from sheep (n?=?28), goat (n?=?27), camel (n?=?14), and water buffalo (n?=?19) were collected from 64 randomly selected herds in Isfahan, Chaharmahal va Bakhtiari, and Khuzestan provinces, Iran, and tested for staphylococcal enterotoxins (SEs) presence by enzyme-linked immunosorbent assay method. Out of 88 samples studied, 11 samples (12.5%) were positive for at least one SE. The prevalence rate of SEs contamination in raw sheep, goat, and water buffalo milk samples were 10.7%, 18.5%, and 15.8%. No classical SEs was founded from raw camel milk samples. Of these, four were positive for staphylococcal enterotoxin A (SEA), four for SEC, two SEA and SEC, and one for SEA and SED. None of the samples was positive for SEB and SEE. Statistical evaluation showed that there were no significant differences (P?>?0.05) between the presence of SEs raw sheep, goat, and water buffalo milk samples tested. The quality of Iranian milk is still low, and efforts from the government and the entire productive chain are required to attain consumer safety.  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-23

京公网安备 11010802026262号