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   891篇
  免费   54篇
  国内免费   26篇
耳鼻咽喉   2篇
儿科学   49篇
妇产科学   19篇
基础医学   109篇
口腔科学   25篇
临床医学   169篇
内科学   223篇
皮肤病学   17篇
神经病学   27篇
特种医学   129篇
外科学   33篇
综合类   6篇
预防医学   31篇
眼科学   6篇
药学   101篇
肿瘤学   25篇
  2022年   4篇
  2021年   8篇
  2020年   7篇
  2019年   10篇
  2018年   14篇
  2017年   5篇
  2016年   12篇
  2015年   13篇
  2014年   15篇
  2013年   22篇
  2012年   21篇
  2011年   30篇
  2010年   21篇
  2009年   28篇
  2008年   27篇
  2007年   41篇
  2006年   23篇
  2005年   35篇
  2004年   33篇
  2003年   36篇
  2002年   31篇
  2001年   24篇
  2000年   18篇
  1999年   20篇
  1998年   43篇
  1997年   54篇
  1996年   56篇
  1995年   44篇
  1994年   31篇
  1993年   34篇
  1992年   16篇
  1991年   15篇
  1990年   10篇
  1989年   19篇
  1988年   19篇
  1987年   14篇
  1986年   10篇
  1985年   14篇
  1984年   11篇
  1983年   8篇
  1982年   10篇
  1981年   5篇
  1980年   5篇
  1979年   7篇
  1978年   5篇
  1977年   8篇
  1976年   8篇
  1975年   9篇
  1973年   3篇
  1936年   2篇
排序方式: 共有971条查询结果,搜索用时 0 毫秒
1.
2.
When hCG adsorbs to surfaces, including membranes from tissues that lack specific hCG receptors, it adsorbs with a particular orientation. Some sites on the alpha- and beta-subunits project away from the surface and can be detected with radiolabeled monoclonal antibodies. Other epitopes, which are located on a region on the hormone that presumably contacts the surface, lose their ability to bind antibody. Using antibodies specific for epitopes on hCG which remain exposed and can be detected when the hormone is adsorbed to rat brain homogenates, we found hCG or closely related substances bound to progestational decidual tissues. Immunologically reactive material adsorbed to the decidual tissue increased and decreased in parallel with the serum levels of hCG throughout pregnancy. Binding of labeled monoclonal antibody to substances similar or identical to hCG in other tissues, including placenta and fetal lung, but not red cells, also was identified. Unlike material adsorbed to decidual tissues, receptor-bound hCG was not recognized by any of our alpha-subunit-specific antibodies. This finding suggests either that the adsorbed hormone has a different orientation than receptor-bound hormone or that the adsorbed hormone has dissociated into subunits. These studies represent the first detection of nonreceptor binding of hCG or related molecules to tissues lacking receptors or presumed not to synthesize the hormone. The role of nonreceptor-bound hCG, if any, is unknown. Other than its effects on stimulation of luteal steroidogenesis during early pregnancy, the role of hCG during most of pregnancy has not been determined. Conceivably, the nonreceptor binding we identified is related to a role for hCG in pregnancy that is not associated with an action on the ovarian LH receptor.  相似文献   
3.
de Vries Reilingh  TS  van Geldere  D  Langenhorst  BLAM  de Jong  D  van der Wilt  GJ  van Goor  H  Bleichrodt  RP 《Hernia》2004,8(1):56-59
Polypropylene mesh is widely used for the reconstruction of incisional hernias that cannot be closed primarily. Several techniques have been advocated to implant the mesh. The objective of this study was to evaluate, retrospectively, early and late results of three different techniques, onlay, inlay, and underlay. The records of 53 consecutive patients with a large midline incisional hernia — 25 women and 28 men, mean age 60.4 (range 28–94) — were reviewed. Polypropylene mesh was implanted using the onlay technique in 13 patients, inlay in 23 patients, and underlay in 17 patients. Either the greater omentum or a polyglactin mesh was interponated between the mesh and the viscera. The records of these 53 patients were reviewed with respect to: size and cause of the hernia, pre- and postoperative mortality and morbidity, with special attention to wound complications. Patients were invited to attend the outpatient clinic at least 12 months after implantation of the mesh for physical examination of the abdominal wall. Postoperative complications occurred in 14 (26.4%) patients. The onlay technique had significantly more complications, as compared to both other techniques. Reherniation occurred in 15 (28.3%) patients. The reherniation rate of the inlay technique was significantly higher than after the underlay technique (44% vs 12%, P=0.03) and tended to be higher than the onlay technique (44% vs 23%, P=0.22). Repair of large midline incisional hernias with the use of a polypropylene mesh carries a high risk of complications and has a high reherniation rate. The underlay technique seems to be the better technique.  相似文献   
4.
OBJECTIVE: The aim of the present study was to examine the nature of previously reported deficits in sustained attention and response inhibition in adults with the developmental disorder, phenylketonuria (PKU). METHODS: This study used event-related potentials (ERPs) to examine the performance of PKU adults (n=9) and a matched control group (n=9) on a visual Go-Nogo task. RESULTS: Comparison of behavioural measures between the PKU and control groups failed to reach statistical significance, yet analysis of the ERPs showed statistically significant amplitude reductions in the P1 and N1 components elicited following presentation of stimuli, and a reduction in the amplitude of the N2 component elicited following presentation of Nogo stimuli. CONCLUSIONS: These results suggest that adults with PKU, despite being continuously treated from birth, manifest subtle impairments in distinct aspects of information processing including early sensory processing of visually presented information, as well as impairments in inhibitory functions. SIGNIFICANCE: The results contribute to an understanding of the neurophysiological mechanisms that are implicated in PKU and highlight the sensitivity of ERP techniques for the identification of the loci of information processing deficits in clinical groups.  相似文献   
5.
Olson  MA; Becker  GJ 《Radiology》1986,159(1):25-26
An anomalous pulmonary vein draining into the subdiaphragmatic inferior vena cava was initially demonstrated on computed tomographic (CT) scans. The diagnosis of scimitar syndrome was confirmed with digital subtraction angiography. In retrospect, the anomalous vein and dextroposition of the heart were shown on chest radiographs.  相似文献   
6.
One-hundred and six male children aged 6-23 months with a history of acute watery diarrhoea of less than 72 h duration were randomized to receive either folic acid in a dose of 5 mg at 8-h intervals or placebo for 5 d. There were 54 children in the folic acid group and 52 in the placebo group. The admission characteristics were comparable between the two groups. No significant differences were observed in the intake of oral rehydration solution or stool output between the groups. The mean ± SD of total stool output (g kg−1) was 532 ± 476 vs 479 ± 354 and the duration (h) of diarrhoea was 108 ± 68 vs 103 ± 53 in the folic acid vs placebo group, respectively. The findings, therefore, should have a positive influence on preventing the inappropriate use of folic acid in acute diarrhoea.  相似文献   
7.
The long intracellular half-life of abacavir (ABC) supports its once-daily use, and this would be expected to simplify treatment if ABC could be given as part of a complete once-daily regimen. A randomized double-blind clinical trial compared the efficacy and safety of 600 mg of ABC administered once daily (n = 384) versus 300 mg of ABC administered twice daily (n = 386) in combination with 300 mg of lamivudine (3TC) and 600 mg of efavirenz (EFV) administered once daily in antiretroviral-naive patients over 48 weeks. The baseline median plasma HIV-1 RNA level was 4.89 log10 copies/mL (44% with viral load >100,000 copies/mL), and the median CD4 cell count was 262 cells/mm. ABC administered once daily was non-inferior to the twice-daily regimen, with 66% and 68% of patients in these respective treatment arms achieving a confirmed plasma HIV-1 RNA level <50 copies/mL (95% confidence interval: -8.4%, 4.9%). The ABC once-daily and twice-daily regimens were similar with respect to infrequency of virologic failure (10% vs. 8%), emergence of resistance mutations, CD4 cell increases from baseline (median, 188 vs. 200 cells/mm), safety profile, and incidence of ABC-related hypersensitivity reactions (9% vs. 7%). ABC administered once daily in combination with 3TC and EFV administered once daily was non-inferior to the ABC twice-daily dosing schedule when combined with 3TC and EFV over 48 weeks.  相似文献   
8.
Supravalvular aortic stenosis (SVAS) is an inherited obstructive vascular disease that affects the aorta, carotid, coronary and pulmonary arteries. Previous molecular genetic data have led to the hypothesis that SVAS results from mutations in the elastin gene, ELN. In these studies, the disease phenotype was linked to gross DNA rearrangements (35 and 85 kb deletions and a translocation) in three SVAS families. However, gross rearrangements of ELN have not been identified in most cases of autosomal dominant SVAS. To define the spectrum of ELN mutations responsible for this disorder, we refined the genomic structure of human ELN and used this information in mutational analyses. ELN point mutations co-segregate with the disease in four familial cases and are associated with SVAS in three sporadic cases. Two of the mutations are nonsense, one is a single base pair deletion and four are splice site mutations. In one sporadic case, the mutation arose de novo. These data demonstrate that point mutations of ELN cause autosomal dominant SVAS.   相似文献   
9.
10.
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