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   1575篇
  免费   77篇
  国内免费   4篇
耳鼻咽喉   30篇
儿科学   38篇
妇产科学   18篇
基础医学   224篇
口腔科学   31篇
临床医学   149篇
内科学   304篇
皮肤病学   23篇
神经病学   172篇
特种医学   110篇
外科学   298篇
综合类   12篇
预防医学   66篇
眼科学   18篇
药学   84篇
中国医学   3篇
肿瘤学   76篇
  2023年   18篇
  2022年   29篇
  2021年   41篇
  2020年   26篇
  2019年   30篇
  2018年   53篇
  2017年   29篇
  2016年   44篇
  2015年   37篇
  2014年   57篇
  2013年   87篇
  2012年   106篇
  2011年   105篇
  2010年   58篇
  2009年   50篇
  2008年   106篇
  2007年   111篇
  2006年   82篇
  2005年   99篇
  2004年   81篇
  2003年   79篇
  2002年   73篇
  2001年   12篇
  2000年   12篇
  1999年   9篇
  1998年   13篇
  1997年   10篇
  1996年   9篇
  1995年   6篇
  1994年   6篇
  1993年   7篇
  1992年   11篇
  1991年   13篇
  1990年   12篇
  1988年   9篇
  1987年   6篇
  1986年   6篇
  1985年   8篇
  1984年   10篇
  1982年   5篇
  1981年   5篇
  1980年   4篇
  1979年   6篇
  1975年   5篇
  1974年   5篇
  1933年   14篇
  1931年   4篇
  1930年   5篇
  1913年   4篇
  1912年   5篇
排序方式: 共有1656条查询结果,搜索用时 15 毫秒
1.
2.
3.
40 patients undergoing primary hip arthroplasty, given autologous processed blood transfusion, were randomized to receive no antibiotic prophylaxis (group A, n 20) or cefuroxime (1.5 g single injection; group B, n 20). Bacterial contamination at various steps in the autotransfusion procedure was assessed in liquid and solid culture media. the operation field and the wound drainage blood were never contaminated in either of the groups but some of the suction tips were. Parts of the Vacufix® blood collection bags of group A contained bacteria, but none in group B. Processed red blood cell concentrates in both groups showed bacterial growth. Greater blood loss did not increase the contamination rate in general. Isolated bacteria included the species Staphylococcus epidermidis, coagulase-negative staphylococci and Propionibacteria in both groups, but with different cell counts. in addition, Corynebacterium bovis et minutissimum and Moraxella were identified in group A.

In conclusion, autologous blood transfusion was a safe procedure. If contamination occurred, the bacterial count was low, and the bacteria of low pathogenicity. Antibiotic prophylaxis with cefuroxime reduced this contamination of suction tips and collection bags and limited the transfer of autologous blood products.  相似文献   
4.
The inheritance of alcohol abuse and other psychopathology in 862 men and 913 women adopted by non-relatives, was studied. Both male and female adoptees were at greater risk to develop alcohol abuse if their biological, but not their adoptive, parents were alcoholic. Three types of families with alcoholism were distinguished that differed in frequency of alcohol abuse, somatoform disorders in women and in relation to antisocial behaviour in male adoptees. The combination of both genetic and environmental risk factors was necessary for the development of alcoholism in the most common, milieu-limited type of alcoholism. In families with a less common, male-limited, type of vulnerability, alcohol abuse was highly heritable in men, but women had multiple somatic complaints and seldom abuse. In a third type of family the common vulnerability was expressed as antisocial behaviour with violent criminality and recurrent alcohol abuse in males, but as high frequency somatization in female relatives.  相似文献   
5.
Specific receptors for vitamin D have been identified in human muscle tissue. Cross-sectional studies show that elderly persons with higher vitamin D serum levels have increased muscle strength and a lower number of falls. We hypothesized that vitamin D and calcium supplementation would improve musculoskeletal function and decrease falls. In a double-blind randomized controlled trial, we studied 122 elderly women (mean age, 85.3 years; range, 63-99 years) in long-stay geriatric care. Participants received 1200 mg calcium plus 800 IU cholecalciferol (Cal+D-group; n = 62) or 1200 mg calcium (Cal-group; n = 60) per day over a 12-week treatment period. The number of falls per person (0, 1, 2-5, 6-7, >7 falls) was compared between the treatment groups. In an intention to treat analysis, a Poisson regression model was used to compare falls after controlling for age, number of falls in a 6-week pretreatment period, and baseline 25-hydroxyvitamin D and 1,25-dihydroxyvitamin D serum concentrations. Among fallers in the treatment period, crude excessive fall rate (treatment - pretreatment falls) was compared between treatment groups. Change in musculoskeletal function (summed score of knee flexor and extensor strength, grip strength, and the timed up&go test) was measured as a secondary outcome. Among subjects in the Cal+D-group, there were significant increases in median serum 25-hydroxyvitamin D (+71%) and 1,25-dihydroxyvitamin D (+8%). Before treatment, mean observed number of falls per person per week was 0.059 in the Cal+D-group and 0.056 in the Cal-group. In the 12-week treatment period, mean number of falls per person per week was 0.034 in the Cal+D-group and 0.076 in the Cal-group. After adjustment, Cal+D-treatment accounted for a 49% reduction of falls (95% CI, 14-71%; p < 0.01) based on the fall categories stated above. Among fallers of the treatment period, the crude average number of excessive falls was significantly higher in the Cal-group (p = 0.045). Musculoskeletal function improved significantly in the Cal+D-group (p = 0.0094). A single intervention with vitamin D plus calcium over a 3-month period reduced the risk of falling by 49% compared with calcium alone. Over this short-term intervention, recurrent fallers seem to benefit most by the treatment. The impact of vitamin D on falls might be explained by the observed improvement in musculoskeletal function.  相似文献   
6.
7.
OBJECTIVE: To better understand hepatitis C viropathies and seroprevalence by performing an epidemiologic analysis of pregnant women seropositive for antibody against hepatitis C. METHODS: We studied 1013 consecutive obstetric patients at Parkland Memorial Hospital who gave informed consent for detailed interviews and serotesting. Sera were analyzed for antibody to the hepatitis C virus using both C100-3 and RIBA-4 assays. Neonatal assessment was carried out in the immediate postpartum period. RESULTS: Hepatitis C antibody was detected in 2.28% (N = 23) of the 1005 women in whom analysis was completed. Factors associated with seropositivity included intravenous (IV) drug use, sexually transmitted diseases, hepatitis B infection, maternal age greater than 22.5 years, increased parity (eg, greater than 2.1), history of transfusion, and three or more different lifetime sexual partners or a sexual partner who used IV drugs. Maternal and neonatal outcome was not different between hepatitis C antibody-positive and -negative groups. CONCLUSIONS: Epidemiologic data are consistent with sexual and parenteral modes of transmission. Women with hepatitis C antibody did not have excessive perinatal complications compared with antibody-negative women. A model protocol and cost analysis for screening pregnant women for hepatitis C infection are presented. However, routine screening for hepatitis C is not advocated.  相似文献   
8.
9.
The Brca2 tumor-suppressor gene contributes to genomic stability, at least in part by a role in homologous recombinational repair. BRCA2 protein is presumed to function in homologous recombination through interactions with RAD51. Both exons 11 and 27 of Brca2 code for domains that interact with RAD51; exon 11 encodes eight BRC motifs, whereas exon 27 encodes a single, distinct interaction domain. Deletion of all RAD51-interacting domains causes embryonic lethality in mice. A less severe phenotype is seen with BRAC2 truncations that preserve some, but not all, of the BRC motifs. These mice can survive beyond weaning, but are runted and infertile, and die very young from cancer. Cells from such mice show hypersensitivity to some genotoxic agents and chromosomal instability. Here, we have analyzed mice and cells with a deletion of only the RAD51-interacting region encoded by exon 27. Mice homozygous for this mutation (called brca2(lex1)) have a shorter life span than that of control littermates, possibly because of early onsets of cancer and sepsis. No other phenotype was observed in these animals; therefore, the brca2(lex1) mutation is less severe than truncations that delete some BRC motifs. However, at the cellular level, the brca2(lex1) mutation causes reduced viability, hypersensitivity to the DNA interstrand crosslinking agent mitomycin C, and gross chromosomal instability, much like more severe truncations. Thus, the extreme carboxy-terminal region encoded by exon 27 is important for BRCA2 function, probably because it is required for a fully functional interaction between BRCA2 and RAD51.  相似文献   
10.
Lafora disease (LD) is a fatal and the most common form of adolescent-onset progressive epilepsy. Fulminant endoplasmic reticulum (ER)-associated depositions of starch-like long-stranded, poorly branched glycogen molecules [known as polyglucosans, which accumulate to form Lafora bodies (LBs)] are seen in neuronal perikarya and dendrites, liver, skeletal muscle and heart. The disease is caused by loss of function of the laforin dual-specificity phosphatase or the malin E3 ubiquitin ligase. Towards understanding the pathogenesis of polyglucosans in LD, we generated a transgenic mouse overexpressing inactivated laforin to trap normal laforin's unknown substrate. The trap was successful and LBs formed in liver, muscle, neuronal perikarya and dendrites. Using immunogold electron microscopy, we show that laforin is found in close proximity to the ER surrounding the polyglucosan accumulations. In neurons, it compartmentalizes to perikaryon and dendrites and not to axons. Importantly, it binds polyglucosans, establishing for the first time a direct association between the disease-defining storage product and disease protein. It preferentially binds polyglucosans over glycogen in vivo and starch over glycogen in vitro, suggesting that laforin's role begins after the appearance of polyglucosans and that the laforin pathway is involved in monitoring for and then preventing the formation of polyglucosans. In addition, we show that the laforin interacting protein, EPM2AIP1, also localizes on the polyglucosan masses, and we confirm laforin's intense binding to LBs in human LD biopsy material.  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