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   2708篇
  免费   256篇
  国内免费   8篇
耳鼻咽喉   15篇
儿科学   174篇
妇产科学   26篇
基础医学   385篇
口腔科学   135篇
临床医学   251篇
内科学   743篇
皮肤病学   23篇
神经病学   209篇
特种医学   40篇
外科学   289篇
综合类   9篇
一般理论   1篇
预防医学   170篇
眼科学   9篇
药学   288篇
中国医学   2篇
肿瘤学   203篇
  2023年   13篇
  2021年   19篇
  2020年   32篇
  2019年   41篇
  2018年   50篇
  2017年   49篇
  2016年   44篇
  2015年   48篇
  2014年   74篇
  2013年   102篇
  2012年   112篇
  2011年   121篇
  2010年   75篇
  2009年   88篇
  2008年   127篇
  2007年   119篇
  2006年   107篇
  2005年   143篇
  2004年   126篇
  2003年   104篇
  2002年   94篇
  2001年   116篇
  2000年   98篇
  1999年   76篇
  1998年   54篇
  1997年   39篇
  1996年   35篇
  1995年   43篇
  1994年   44篇
  1993年   28篇
  1992年   66篇
  1991年   59篇
  1990年   61篇
  1989年   53篇
  1988年   50篇
  1987年   35篇
  1986年   49篇
  1985年   46篇
  1984年   30篇
  1983年   32篇
  1982年   22篇
  1981年   32篇
  1980年   15篇
  1979年   20篇
  1978年   17篇
  1977年   13篇
  1975年   12篇
  1974年   12篇
  1973年   13篇
  1970年   14篇
排序方式: 共有2972条查询结果,搜索用时 15 毫秒
1.
2.
3.
Loss of function variants in NOTCH1 cause left ventricular outflow tract obstructive defects (LVOTO). However, the risk conferred by rare and noncoding variants in NOTCH1 for LVOTO remains largely uncharacterized. In a cohort of 49 families affected by hypoplastic left heart syndrome, a severe form of LVOTO, we discovered predicted loss of function NOTCH1 variants in 6% of individuals. Rare or low-frequency missense variants were found in 16% of families. To make a quantitative estimate of the genetic risk posed by variants in NOTCH1 for LVOTO, we studied associations of 400 coding and noncoding variants in NOTCH1 in 1,085 cases and 332,788 controls from the UK Biobank. Two rare intronic variants in strong linkage disequilibrium displayed significant association with risk for LVOTO amongst European-ancestry individuals. This result was replicated in an independent analysis of 210 cases and 68,762 controls of non-European and mixed ancestry. In conclusion, carrying rare predicted loss of function variants in NOTCH1 confer significant risk for LVOTO. In addition, the two intronic variants seem to be associated with an increased risk for these defects. Our approach demonstrates the utility of population-based data sets in quantifying the specific risk of individual variants for disease-related phenotypes.  相似文献   
4.
Abstract The aim of the present clinical trial was to test tolerability during 2 treatments with EMDOGAIN® in a large number of patients. An open, controlled study design in 10 Swedish specialist clinics was chosen, with a test group of 107 patients treated with EMDOGAIN® in connection with periodontal surgery at 2 surgical test sites per patient. The procedures were performed 2 to 6 weeks apart on one-rooted teeth with at least 4 mm deep intraosseous lesions. A control group of 33 patients underwent flap surgery without EMDOGAIN® at I comparable site. In total 214 test and 33 control surgeries were performed. Serum samples were obtained from test patients for analysis of total and specific antibody levels. 10 of the patients had samples taken before and after the first surgery. 56 other samples were taken after one treatment with EMDOGAIN®, and 63 after 2 treatments. None of the samples, not even from allergy-prone patients after 2 treatments, indicated deviations from established baseline ranges. This indicates that the immunogenic potential of EMDOGAIN® is extremely low when applied in conjunction with periodontal surgery. Comparison between the test and control groups demonstrated the same type and frequency of post-surgical experiences, i.e., reactions caused by the surgical procedure itself. Clinical probing and radiographic evaluation was performed at baseline and 8 months postsurgery. About half of the patients (44 test and 21 control) were also evaluated after 3 years. There was a significant difference between the test and control results at 8 months post surgery. and this difference had increased further at the 3 year follow-up. The 2.5–3 mm increase in attachment and bone level after treatment with EMDOGAIN® was of the same magnitude as seen in the studies with split-mouth design aiming for lest of effectiveness of EMDOGAIN®.  相似文献   
5.
6.
Protein composition and mechanical function of intermediate filaments were examined in arteries of different sizes using desmin deficient mice (Des−/−) and their wild-type controls (Des+/+). Using SDS-PAGE gels and Western blots we found a gradient in desmin expression in the arterial tree; the desmin content increased from the elastic artery aorta, via the muscular mesenteric artery to the resistance-sized mesenteric microarteries ∼150 μm in diameter in Des+/+ mice. Mechanical experiments were performed on the aorta, the mesenteric artery and resistance-sized arteries using wire myographs. For aorta and mesenteric artery, no differences in passive or active circumference- stress relations were found between Des−/− and Des+/+ mice. In microarteries, both passive and active stress were lower in the Des−/− group. In conclusion, large elastic and muscular arteries contain a relatively low amount of desmin, and the desmin intermediate filaments do not seem to play a major role in the mechanical properties of these larger arterial vessels. In the microarteries, where expression of desmin is high, desmin plays a role in supporting both passive and active tension.  相似文献   
7.
8.
The effects of endothelin-1 (human, porcine) on contractions induced by transmural nerve stimulation, exogenous ATP or noradrenaline, and on the release of [3H]noradrenaline were studied in guinea pig and rat vas deferens. Endothelin enhanced nerve-induced contractile responses, increased basal muscle tone and increased the contractile response to exogenous ATP in both guinea pig and rat vas deferens. Endothelin did not affect the contractile responses to exogenous noradrenaline. The calcium channel blocker felodipine antagonized the stimulating effects of endothelin in the rat vas deferens, whereas blockade of lipoxygenase and cyclooxygenase pathways by a combination of BW 755C and indomethacin was without effect. In rat vas deferens preparations preincubated with [3H]noradrenaline, endothelin inhibited the 3H overflow induced by transmural stimulation, although the contractile responses were enhanced by endothelin. Pretreatment with forskolin or felodipine did not abolish the endothelin inhibition of radiotracer overflow. In conclusion, endothelin can modulate adrenergic and purinergic neuroeffector transmission in both guinea pig and rat vas deferens via inhibitory prejunctional and stimulant postjunctional mechanisms. The stimulant postjunctional effect seemed to predominate in our experiments.  相似文献   
9.
Ultrasound guided biopsy of the prostate with fine needle (22G) as well as trucut needle (18G) was performed in 145 patients with a suspicion of prostate cancer. After three weeks all patients were interviewed about complications associated with the biopsy. Hematuria and/or hemospermia occurred in 2/3 of the patients. None of the hemorrhages was severe and all ceased spontaneously. E. coli infection of the urinary tract occurred in 9 cases (6.2%). Five of the infections caused high fever and necessitated hospital care with parenteral antibiotics for 1 to 8 days. The patients with infection had no signs of immunological defects by which they might have been identified before the biopsy. As a consequence of these observations we now use prophylactic antibiotics when core biopsy of the prostate is performed transrectally.  相似文献   
10.
The effect of cooking time on mutagenic activity in crust, pan residue and smoke from pan-broiled pork patties was studied in the Ames Salmonella mutagenicity test system. The effect on mutagenicity of reheating the cooked patties and of keeping them warm was also studied. The meat was broiled at 200 degrees C for various times between 2 and 10 min. Broiled meat was reheated up to 5 times at 200 degrees C, each time to a centre temperature of 70 degrees C. Reheating was also performed in a microwave oven for 2 min and in an electric oven at 200 degrees C for 10 min. In addition, broiled patties were kept warm at 60 degrees C in an incubator for up to 9 hr. The mutagenic activity increased rapidly in all fractions except the volatile phase over the first 6 min of cooking, after which time only a slight increase was seen. At cooking times below 4 min no mutagenic activity was detected in the smoke. Reheating or keeping the meat warm for up to 9 hr had very little effect on the mutagenic activity of the meat. Reversed-phase high-performance liquid chromatography mutagenicity profiles of the aerosol, crust and pan-residue extracts showed no major qualitative differences in samples cooked at different times. It is concluded that during pan broiling at 200 degrees C the major part of the mutagenic activity is formed during the first 6 min of cooking. Reheating the meat or keeping it warm does not significantly affect the mutagenic activity. No major additional mutagens are formed during continued heating for up to 25 min.  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