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   594篇
  免费   27篇
  国内免费   1篇
耳鼻咽喉   4篇
儿科学   18篇
妇产科学   6篇
基础医学   61篇
口腔科学   5篇
临床医学   53篇
内科学   192篇
皮肤病学   6篇
神经病学   41篇
特种医学   25篇
外科学   30篇
综合类   4篇
预防医学   76篇
眼科学   46篇
药学   23篇
中国医学   3篇
肿瘤学   29篇
  2023年   4篇
  2022年   15篇
  2021年   23篇
  2020年   4篇
  2019年   10篇
  2018年   12篇
  2017年   11篇
  2016年   8篇
  2015年   10篇
  2014年   15篇
  2013年   11篇
  2012年   31篇
  2011年   28篇
  2010年   19篇
  2009年   17篇
  2008年   27篇
  2007年   43篇
  2006年   26篇
  2005年   36篇
  2004年   39篇
  2003年   29篇
  2002年   31篇
  2001年   15篇
  2000年   6篇
  1999年   6篇
  1997年   4篇
  1995年   3篇
  1993年   3篇
  1992年   10篇
  1991年   7篇
  1990年   8篇
  1989年   4篇
  1988年   5篇
  1987年   4篇
  1986年   5篇
  1985年   8篇
  1984年   7篇
  1983年   5篇
  1981年   5篇
  1979年   7篇
  1978年   6篇
  1977年   3篇
  1975年   4篇
  1974年   3篇
  1973年   4篇
  1972年   9篇
  1971年   4篇
  1969年   4篇
  1968年   6篇
  1966年   3篇
排序方式: 共有622条查询结果,搜索用时 15 毫秒
1.
2.
3.
A woman with an eight-year history of polycythemia vera presented with numbness and weakness of both legs. A large spinal haematoma was revealed on magnetic resonance imaging which was treated clinically and which subsequently resolved.  相似文献   
4.
A suspected diagnosis of retinoblastoma can almost always be supported by intraocular calcification detected by computerized tomography. We report two patients with diffuse unilateral opacification of the ocular media who failed to demonstrate calcification on a CT scan.  相似文献   
5.
The anterior or rostrolateral prefrontal cortex (RLPFC) is frequently recruited during complex cognitive tasks across a wide range of domains, including reasoning, long-term memory retrieval, and working memory. The authors report an event-related functional MRI study, indicating that the RLPFC is specifically involved in the evaluation of internally generated information--or information that cannot be readily perceived from the external environment but has to be inferred or self-generated. The findings are consistent with a hierarchical model of lateral prefrontal organization, with RLPFC contributing only at the highest orders of cognitive transformations. This characterization of RLPFC function may help explain seemingly disparate findings across multiple cognitive domains and could provide a unified account of this region's contribution to human cognition.  相似文献   
6.
Archives of Sexual Behavior - Adolescence is a critical time in the U.S. for religious development in that many young people eschew their religious identity as they enter adulthood. In general,...  相似文献   
7.
M E Chittum  R E Kalina 《Ophthalmology》1987,94(9):1114-1119
Acute retinal pigment epitheliitis is an infrequently described macular disorder of unknown cause that affects healthy young adults. Acute symptoms include either reduced visual acuity or central scotoma. Ophthalmoscopy discloses discrete pigment clumps with surrounding hypopigmented halos in the center of the macula. Inflammatory signs are mild or absent. The hypopigmented areas show transmission hyperfluorescence without leakage on fluorescein angiography. Symptoms subside spontaneously although retinal pigment epithelial (RPE) changes are usually permanent. Central serous choroidopathy, macular edema, or permanently decreased vision have not developed in any of the eight patients we have followed for up to 8 years. Accurate identification of retinal pigment epitheliitis as a specific clinical entity is important because of the good prognosis without treatment.  相似文献   
8.
The carbonic anhydrase inhibitor, 6-amino-2-benzothiazolesulfonamide, formulated as a 3% suspension in a gel vehicle was instilled in one eye of 21 human subjects in a single dose study to determine its effect on aqueous dynamics. A small but statistically significant effect on aqueous humor flow was observed 2 to 7 hours after application. By 8 hours, the effect had disappeared, and intraocular pressure (IOP) measured 8 hours after application of a single dose was unchanged in these normal volunteers. The drug and its vehicle caused local side effects including irritation, hyperemia, and blurred vision. The authors wondered if multiple doses would produce a greater effect. Four subjects received up to four doses of the drug over 2 days and were restudied. Marked bulbar injection and follicular conjunctivitis, attributable to either the drug or the vehicle, developed in two of the subjects, both contact lens wearers. A milder form of bulbar injection and follicular conjunctivitis developed in a third subject, who received three doses of the drug and was not a contact lens wearer. These side effects precluded additional multiple-dose testing of this formulation of the drug, and no conclusions about the effect of the drug on aqueous flow can be drawn from this portion of the study.  相似文献   
9.
We aimed to assess the feasibility of ultrasound-based tissue attenuation imaging (TAI) and tissue scatter distribution imaging (TSI) for quantification of liver steatosis in patients with nonalcoholic fatty liver disease (NAFLD). We prospectively enrolled 101 participants with suspected NAFLD. The TAI and TSI measurements of the liver were performed with a Samsung RS85 Prestige ultrasound system. Based on the magnetic resonance imaging proton density fat fraction (MRI-PDFF), patients were divided into ≤5%, 5–10%, and ≥10% of MRI-PDFF groups. We determined the correlation between TAI, TSI, and MRI-PDFF and used multiple linear regression analysis to identify any association with clinical variables. The diagnostic performance of TAI, TSI was determined based on the area under the receiver operating characteristic curve (AUC). The intraclass correlation coefficient (ICC) was calculated to assess interobserver reliability.Both TAI (rs = 0.78, P < .001) and TSI (rs = 0.68, P < .001) showed significant correlation with MRI-PDFF. TAI overperformed TSI in the detection of both ≥5% MRI-PDFF (AUC = 0.89 vs 0.87) and ≥10% (AUC = 0.93 vs 0.86). MRI-PDFF proved to be an independent predictor of TAI (β = 1.03; P < .001), while both MRI-PDFF (β = 50.9; P < .001) and liver stiffness (β = −0.86; P < .001) were independent predictors of TSI. Interobserver analysis showed excellent reproducibility of TAI (ICC = 0.95) and moderate reproducibility of TSI (ICC = 0.73).TAI and TSI could be used successfully to diagnose and estimate the severity of hepatic steatosis in routine clinical practice.  相似文献   
10.
Biochar is a versatile carbon-rich organic material originating from pyrolyzed biomass residues that possess the potential to stabilize organic carbon in the soil, improve soil fertility and water retention, and enhance plant growth. For the utilization of biochar as a soil conditioner, the mutual interconnection of the physicochemical properties of biochar with the production conditions used during the pyrolysis (temperature, heating rate, residence time) and the role of the origin of used biomass seem to be crucial. The aim of the research was focused on a comparison of the properties of biochar samples (originated from oat brans, mixed woodcut, corn residues and commercial compost) produced at different temperatures (400–700 °C) and different residence times (10 and 60 min). The results indicated similar structural features of produced biochar samples; nevertheless, the original biomass showed differences in physicochemical properties. The morphological and structural analysis showed well-developed aromatic porous structures for biochar samples originated from oat brans, mixed woodcut and corn residues. The higher pyrolysis temperature resulted in lower yields; however, it provided products with higher content of organic carbon and a more developed surface area. The lignocellulose biomass with higher contents of lignin is an attractive feedstock material for the production of biochar with potential agricultural applications.  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