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   614篇
  免费   61篇
  国内免费   5篇
耳鼻咽喉   5篇
儿科学   37篇
妇产科学   6篇
基础医学   71篇
口腔科学   20篇
临床医学   91篇
内科学   151篇
皮肤病学   2篇
神经病学   38篇
特种医学   34篇
外科学   43篇
综合类   5篇
预防医学   75篇
眼科学   1篇
药学   53篇
中国医学   1篇
肿瘤学   47篇
  2024年   2篇
  2023年   9篇
  2022年   25篇
  2021年   42篇
  2020年   19篇
  2019年   15篇
  2018年   37篇
  2017年   19篇
  2016年   14篇
  2015年   29篇
  2014年   25篇
  2013年   34篇
  2012年   48篇
  2011年   27篇
  2010年   23篇
  2009年   23篇
  2008年   33篇
  2007年   32篇
  2006年   21篇
  2005年   20篇
  2004年   19篇
  2003年   20篇
  2002年   22篇
  2001年   7篇
  2000年   3篇
  1999年   4篇
  1998年   9篇
  1997年   7篇
  1996年   7篇
  1995年   3篇
  1994年   6篇
  1993年   3篇
  1992年   7篇
  1991年   4篇
  1990年   6篇
  1989年   8篇
  1988年   5篇
  1987年   4篇
  1986年   4篇
  1985年   13篇
  1984年   4篇
  1983年   4篇
  1981年   1篇
  1980年   4篇
  1979年   1篇
  1978年   2篇
  1977年   2篇
  1976年   1篇
  1975年   2篇
  1967年   1篇
排序方式: 共有680条查询结果,搜索用时 46 毫秒
41.
Objective: To report ventilation strategies, survival and complications in 39 outborn infants treated with high frequency oscillatory ventilation (HFOV).
Methodology Data were collected prospectively between 1 May 1992 and 31 December 1993 on all infants treated with HFOV who had severe respiratory failure despite optimal conventional ventilation.
Results Twenty-eight out of 39 (72%) survived. Of the 15 infants with birthweights <1500g, eight survived. Best survival rates were for infants with pulmonary interstitial emphysema with air leak (4/5) and for infants of birthweight >1500g with hyaline membrane disease (8/8), and meconium aspiration syndrome (7/7). Three infants deteriorated while on HFOV and required extracorporeal membrane oxygenation. Complications were: (i) development of pulmonary interstitial emphysema (1); (ii) recurrence of pneumothorax (3); (iii) hypotension (2); and (iv) bronchopulmonary dysplasia (9). One of the eight infants weighing <1500g who received HFOV in the first week of life developed periventricular haemorrhage.
Conclusion The initial results of HFOV for severe respiratory failure were encouraging although a learning curve was encountered with its introduction.  相似文献   
42.
The undesirable side effects and variable efficacy of some oral live rotavirus vaccines in infants have necessitated alternative vaccine approaches. We evaluated a recombinant RFVP2/WaVP6 rotavirus-like-particle (2/6VLP) oral vaccine, using an immunostimulating complex (ISCOM) matrix as adjuvant, in a gnotobiotic (Gn) pig model of human rotavirus (HRV) disease. The 2/6VLPs adhered to the ISCOM-matrix (2/6VLP-ISCOM ) and were antigenic, but they failed to induce protection. However, when combined with attenuated (Att) HRV for oral priming, the 2/6VLP-ISCOM vaccine was effective as a booster and induced partial protection against virulent Wa HRV. The 250 microg 2/6VLP dose was more effective than 100 microg. The highest mean numbers of IgA antibody secreting cells evaluated by ELISPOT in intestinal lymphoid tissues were in pigs receiving AttHRV+2/6VLP-ISCOM or three doses of AttHRV and were associated with the highest protection rates.  相似文献   
43.
The mutagenicity of cis-diamminedichloroplatinum(II) (DDP; cisplatin) and the rate at which resistance develops with repeated exposure to DDP are dependent on mutagenic translesional replication across DDP DNA adducts, mediated in part by DNA polymerase zeta, and on the integrity of the DNA mismatch repair (MMR) system. The aim of this study was to determine whether disabling Pol zeta by suppressing expression of its hREV3 subunit in human cancer cells can reduce the mutagenicity of DDP and whether loss of MMR facilitates mutagenic Pol zeta-dependent translesional bypass. The HCT116+ch3 (MMR(+)/REV3(+)) and HCT116 (MMR(-)/REV3(+)) human colon carcinoma cell lines were engineered to suppress hREV3 mRNA by stable expression of a short hairpin interfering RNA targeted to hREV3. The effect of knocking down REV3 expression was to completely offset the DDP resistance mediated by loss of MMR. Knockdown of REV3 also reduced the mutagenicity of DDP and eliminated the enhanced mutagenicity of DDP observed in the MMR(-)/REV3(+) cells. Similar results were obtained when the ability of the cells to express luciferase from a platinated plasmid was measured. We conclude that Pol zeta plays a central role in the mutagenic bypass of DDP adducts and that the DDP resistance, enhanced mutagenicity, and the increased capacity of MMR(-)/REV3(+) cells to express a gene burdened by DDP adducts are all dependent on the Pol zeta pathway.  相似文献   
44.
The discovery of two distinct isoenzymes of COX has led to the development and clinical introduction of COX-2 inhibitors with increased selectivity onto the market. Meloxicam is a non-steroidal anti-inflammatory drug (NSAID) of the oxicam class, and is a preferential inhibitor of COX-2, demonstrating effectiveness with anti-inflammatory, analgesic and antipyretic activity. Meloxicam is therapeutically utilised in the management of osteoarthritis and rheumatoid arthritis. Trials have examined the risk of gastrointestinal ulceration of meloxicam when compared with traditional non-specific COX-inhibiting NSAIDs with mixed results; meloxicam seems to have a greater gastrointestinal risk than the highly specific COX-2 NSAIDs. Meloxicam has a plasma half-life of approximately 20 h and is convenient for once daily administration. Neither moderate renal nor hepatic insufficiency significantly alters the pharmacokinetics of meloxicam in short-term studies. Furthermore, dose adjustment is not required in the elderly. Recent drug-drug interaction studies have demonstrated that meloxicam interacts with some medications, including cholestyramine, lithium and some inhibitors of cytochrome P450 -2C9 and -3A4. Consequently, increased clinical vigilance should be maintained when coprescribing some medications with meloxicam. Concentration-dependent therapeutic and toxicological effects have yet to be extensively elucidated for meloxicam. Long-term safety in various organ systems, especially in the heart and vascular system and with concomitant drug administration, remains to be proven. The pharmacokinetics of meloxicam enables once daily application, which increases compliance compared with some shorter acting NSAIDs; however, long-term clinical data clearly demonstrating safety and efficacy advantages are lacking.  相似文献   
45.
46.
Genetics and early disturbances of breathing control   总被引:4,自引:0,他引:4  
Early disturbances in breathing control, including apneas of prematurity and apparently life-threatening events, account for some cases of sudden infant death syndrome and for a rare disorder called congenital central hypoventilation syndrome (CCHS). Data suggesting a genetic basis for CCHS have been obtained. Recently, we found heterozygous de novo mutations of the PHOX2B gene in 18 of 29 individuals with CCHS. Most mutations consisted of five to nine alanine expansions within a 20-residue polyalanine tract, probably resulting from nonhomologous recombination. Other mutations, generally inherited from one of the parents, in the coding regions of genes involved in the endothelin and RET signaling pathways and in the brain-derived-neurotrophic factor (BDNF) gene have been found in a few CCHS patients. Interestingly, all these genes are involved in the development of neural crest cells. Targeted disruption of these genes in mice has provided information on the pathophysiological mechanisms underlying CCHS. Despite the identification of these genes involved in breathing control, none of the genetically engineered mice developed to date replicate the full human CCHS respiratory phenotype. Recent insights into the genetic basis for CCHS may shed light on the genetics of other early disturbances in breathing control, such as apnea of prematurity and sudden infant death syndrome.  相似文献   
47.
Previous studies of transformed rodent fibroblasts have suggested that specific isoforms of the actin-binding protein tropomyosin (TM) could function as suppressors of transformation, but an analysis of TM expression in patient tumor tissue is limited. The purpose of our study was to characterize expression of the different TM isoforms in human transitional cell carcinoma of the urinary bladder by immunohistochemistry and Western blot analysis. We found that TM1 and TM2 protein levels were markedly reduced and showed >60% reduction in 61% and 55% of tumor samples, respectively. TM5, which was expressed at very low levels in normal bladder mucosa, exhibited aberrant expression in 91% of tumor specimens. The Western blot findings were confirmed by immunohistochemical analysis in a number of tumors. We then investigated the mechanism underlying TM expression deregulation, in the T24 human bladder cancer cell line. We showed that levels of TM1, TM2 and TM3 are reduced in T24 cells, but significantly upregulated by inhibition of the mitogen-activated protein kinase-signaling pathway. In addition, inhibition of this pathway was accompanied by restoration of stress fibers. Overall, changes in TM expression levels seem to be an early event during bladder carcinogenesis. We conclude that alterations in TM isoform expression may provide further insight into malignant transformation in transitional cell carcinomas of the bladder and may be a useful target for early detection strategies.  相似文献   
48.
49.
Many pharmaceutically relevant molecules are still extracted directly from lignocellulosic biomass sources. As this can be a bottleneck in supply, total quantification followed by total extraction are desirable processes to ensure as much as possible is obtained, at the optimal time in the growth cycle. Herein we report the application of solid-state 13C nuclear magnetic resonance (NMR) spectroscopy to quantify shikimic acid present inside Chinese star anise (or star aniseed, llicium verum). Subsequently, methanol soxhlet extraction is compared with conventional aqueous hydroxides (i.e. sodium hydroxide) and cellulose-dissolving aqueous hydroxides (i.e. tetraethylammonium and tetrabutylammonium hydroxide) for shikimic acid isolation. Methanol extraction isolated ca. 6.6±0.1 wt% (wt%) shikimic acid (post-purification), and solid-state NMR confirmed extraction was incomplete even after 72 h. Conversely, dissolution of the star anise at room temperature in tetrabutylammonium hydroxide ([N4444]OH) allowed isolation of ca. 14.0±0.6 wt% shikimic acid (post-purification). Solid state NMR confirmed the star anise initially contained 19±3 wt% shikimic acid, which was quantitatively extracted after dissolution in the aqueous hydroxide solution. The solubility of the star anise and the kinetics of the shikimic acid extraction were also briefly evaluated.  相似文献   
50.
Long term health related quality of life (HRQL) and nutritional outcome of patients following esophagectomy for cancer has become increasingly significant as the 5-year survival rate in this patient group is increasing. This meta-analysis aims to investigate the HRQOL, nutritional impact symptoms and nutritional outcomes of patients following an esophagectomy at greater than 12 months after surgery.

In studies reporting on HRQL as an outcome, global QOL score at 6-month compare to greater than 12-month showed no statistically significant difference (65.92 vs. 75.78, p = 0.07). Forty-one percent of patients reported a greater than 10% weight loss at six-month follow-up (95% CI: 20–65%; I2 = 94.27, p < 0.001), and at the greater than 12-month follow-up, 33% of patients had the greater than 10% weight loss (95% CI: 15–57%; I2 = 96.18, p < 0.001). At the 12-month or longer post esophagectomy, just over half the patients reported dysphagia (51%, 95% CI: 25–76%; I2 = 95.70, p < 0.001), nausea was reported by 11% (95% CI: 7–19%; I2 = 59.31, p = 0.09), dumping syndrome reported by 60% (95% CI: 43–76%; I2 = 96.92, p < 0.001).

Symptoms such as dysphagia, diarrhea, reflux, dumping syndrome, and nausea were found to persist following esophagectomy. There were insufficient robust research investigating how these symptoms impact on the adequacy of dietary intake and micronutrient status.  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