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   7962篇
  免费   731篇
  国内免费   10篇
耳鼻咽喉   169篇
儿科学   235篇
妇产科学   147篇
基础医学   1018篇
口腔科学   186篇
临床医学   961篇
内科学   1303篇
皮肤病学   110篇
神经病学   857篇
特种医学   241篇
外科学   944篇
综合类   155篇
一般理论   16篇
预防医学   1070篇
眼科学   85篇
药学   570篇
  1篇
中国医学   7篇
肿瘤学   628篇
  2023年   59篇
  2022年   86篇
  2021年   213篇
  2020年   156篇
  2019年   212篇
  2018年   221篇
  2017年   185篇
  2016年   166篇
  2015年   189篇
  2014年   227篇
  2013年   364篇
  2012年   453篇
  2011年   493篇
  2010年   266篇
  2009年   212篇
  2008年   370篇
  2007年   455篇
  2006年   414篇
  2005年   394篇
  2004年   359篇
  2003年   315篇
  2002年   299篇
  2001年   154篇
  2000年   154篇
  1999年   145篇
  1998年   69篇
  1997年   64篇
  1996年   58篇
  1995年   52篇
  1993年   48篇
  1992年   114篇
  1991年   175篇
  1990年   128篇
  1989年   90篇
  1988年   100篇
  1987年   76篇
  1986年   94篇
  1985年   80篇
  1984年   75篇
  1983年   54篇
  1982年   46篇
  1979年   78篇
  1978年   48篇
  1977年   46篇
  1975年   53篇
  1974年   58篇
  1973年   53篇
  1972年   51篇
  1971年   49篇
  1970年   46篇
排序方式: 共有8703条查询结果,搜索用时 0 毫秒
41.
This study investigated relationships between child/parent dissatisfaction with child facial appearance and the self-concept/social competence of 8- to 15-year-old children with (N = 34) and without (N = 34) oral clefts. Children in both groups had normative psychosocial adjustment, but also reported moderate dissatisfaction with facial appearance. Cleft group parents were more likely to agree with their child's dissatisfaction. When cleft group parents were more dissatisfied with child facial appearance, their children reported better quality of life. Results suggest that parents of children with clefts reporting greater dissatisfaction may respond in positive ways that enhance quality of life.  相似文献   
42.
An increased risk of end-stage renal disease (ESRD) among blacks has been previously shown for most causes of chronic renal failure, including diabetes. Most previous studies have not considered the higher prevalence of diabetes in the black population and have not analyzed relative risk by type of diabetes. We found that the incidence of ESRD among blacks with diabetes was 3.6 times the rate in whites with diabetes. The relative risk for blacks increases progressively with age, reaching a maximum of 6.9 in persons over the age of 65. The incidence of ESRD due to diabetes is higher in the population with type I diabetes (492 per 100,000) than in the population with type II diabetes (71 per 100,000). Blacks have a higher incidence of ESRD in both type I diabetes (odds ratio, 2.96; 95% confidence interval, 1.8 to 4.9) and type II diabetes (odds ratio, 4.9; 95% confidence interval, 3.6 to 6.5). The incidence of ESRD in patients with diabetes varies with age, race, and type of diabetes.  相似文献   
43.
Both HIV infection and methamphetamine dependence can be associated with brain dysfunction. Little is known, however, about the cognitive effects of concurrent HIV infection and methamphetamine dependence. The present study included 200 participants in 4 groups: HIV infected/methamphetamine dependent (HIV+/METH+), HIV negative/methamphetamine dependent (HIV-/METH+), HIV infected/methamphetamine nondependent (HIV+/METH-), and HIV negative/methamphetamine nondependent (HIV-/METH-). Study groups were comparable for age, education, and ethnicity, although the HIV-/METH- group had significantly more females. A comprehensive, demographically corrected neuropsychological battery was administered yielding a global performance score and scores for seven neurobehavioral domains. Rates of neuropsychological impairment were determined by cutoff scores derived from performances of a separate control group and validated with larger samples of HIV+ and HIV- participants from an independent cohort. Rates of global neuropsychological impairment were higher in the HIV+/METH+ (58%), HIV-/METH+ (40%) and HIV+/METH- (38%) groups compared to the HIV-/METH- (18%) group. Nonparametric analyses revealed a significant monotonic trend for global cognitive status across groups, with least impairment in the control group and highest prevalence of impairment in the group with concurrent HIV infection and methamphetamine dependence. The results indicate that HIV infection and methamphetamine dependence are each associated with neuropsychological deficits, and suggest that these factors in combination are associated with additive deleterious cognitive effects. This additivity may reflect common pathways to neural injury involving both cytotoxic and apoptotic mechanisms.  相似文献   
44.
Summary Cystinuria is an inherited condition affecting the active transport of the diamino acids cystine, ornithine, lysine and arginine across the renal tubule and the small intestine. The only clinical effect is the production of urinary tract stones and if these can be prevented the affected individuals can lead a normal life. In many people cystine stones can be dissolved and new stone formation prevented by a high fluid intake, but if this does not succeed regular treatment with penicillamine will do so. Although many side-effects have been described with penicillamine treatment it is rare for them to be severe enough to prevent its use in patients with cystinuria. Since the clinical effects of cystinuria can be prevented by either a high fluid intake or by penicillamine it is important to make the diagnosis in affected individuals as soon as possible and cystinuria should therefore be considered in all people (regardless of age) who form urinary stones.  相似文献   
45.
Recently, divergent reports on the role of mast cells (MC) in different glomerular diseases have brought our attention to their role in an accelerated model of anti-glomerular basement membrane (GBM) glomerulonephritis (GN). Genetically MC-deficient Kit(W)/Kit(W-v) mice, MC-reconstituted Kit(W)/Kit(W-v) mice and Kit+/+ control mice were subjected to anti-GBM GN. Kit(+/+) mice developed moderate proteinuria and glomerular damage following the induction of anti-GBM nephritis. In contrast, proteinuria and glomerular damage were dramatically increased in MC-deficient Kit(W)/Kit(W-v) mice. MC-reconstituted Kit(W)/Kit(W-v) mice showed proteinuria and glomerular damage comparable to Kit+/+ mice. A significant increase in infiltrating T cells and macrophages was detected in MC-deficient Kit(W)/Kit(W-v) mice as compared to Kit+/+ control mice and MC-reconstituted Kit(W)/Kit(W-v) mice. Accordingly, we observed an increase of TGF-beta1 mRNA in kidneys from Kit(W)/Kit(W-v) mice. Interestingly, we did not detect MC in the kidney using either Giemsa staining or RT-real-time PCR, but MC were found in the regional lymph nodes. Finally, mortality of Kit(W)/Kit(W-v) mice was significantly increased after the induction of anti-GBM GN due to uremia. Our report provides the first direct evidence that MC are protective in anti-GBM GN, possibly by modulating the influx of effector T cells and macrophages to inflammatory sites in the kidney.  相似文献   
46.
This research was undertaken to study the fate of Type 2 cells after they have divided. To accomplish this, male rats were exposed to NO2 to increase the number of dividing Type 2 cells. Dividing cells were labeled with 3H-TdR and studied with autoradiographic techniques in the electron microscope for up to 14 days after labeling. The results show that initially most of the 3H-TdR labeled cells were Type 2. However, by 2 days there was a decrease in frequency of labeled Type 2 cells and a large increase in labeled Type 1 cells. The new frequencies of labeled alveolar epithelial cells were stable from 2 through 14 days. This evidence supports the interpretation that Type 2 cells may transform into Type 1 cells. In addition, it was shown that under the conditions of this experiment: (1) the time for transformation was about 2 days, and (2) during this process an intermediate cell type was present.  相似文献   
47.
48.
Oxidative phosphorylation in smooth muscle   总被引:2,自引:0,他引:2  
  相似文献   
49.
The prevalence of human T-cell lymphotropic virus type 1 (HTLV-1) and HTLV-2 infection in 1992 and 1993 was determined by testing 2,152 specimens from injection drug users living in 11 geographic areas in Spain. Results obtained by an authentic HTLV-1 and -2 test were compared with those obtained by an HTLV-1 assay. HTLV infection was identified in 7 of 11 regions, with an overall prevalence of 2.5% (range, 0.4 to 11.5%). Fourty-four (81%) of 54 subjects were infected with HTLV-2; the viral strains in the remaining 10 subjects could not be serologically typed. Underestimation of HTLV infection because of the low sensitivities of HTLV-1 enzyme immunoassays for HTLV-2 antibody was relatively low (< 20%). Therefore, previous epidemiologic findings generated with HTLV-1 enzyme immunoassays appear to be reasonably accurate. Our results suggest that the rate of HTLV infection may have been increasing recently among Spanish drug users.  相似文献   
50.
The nucleotide sequences of variable segments (VS) 1, 2, and 4 for the major outer membrane protein gene (omp1) of Chlamydia trachomatis were determined for serologically defined subtypes D', I', and L2'. Asymmetric DNA amplification was used to produce single-stranded DNA for direct sequencing. Amino acid substitutions were detected in VS1, VS2, and VS4 for I', in VS2 for L2', and in VS4 for D'. DNA sequencing of omp1 variant regions may be an important method for evaluating the molecular epidemiology of Chlamydia spp.  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