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   4314篇
  免费   232篇
  国内免费   14篇
耳鼻咽喉   31篇
儿科学   167篇
妇产科学   72篇
基础医学   513篇
口腔科学   74篇
临床医学   379篇
内科学   914篇
皮肤病学   66篇
神经病学   380篇
特种医学   433篇
外科学   427篇
综合类   92篇
一般理论   1篇
预防医学   298篇
眼科学   240篇
药学   199篇
中国医学   9篇
肿瘤学   265篇
  2022年   27篇
  2021年   35篇
  2020年   40篇
  2019年   48篇
  2018年   66篇
  2017年   55篇
  2016年   70篇
  2015年   79篇
  2014年   115篇
  2013年   172篇
  2012年   204篇
  2011年   204篇
  2010年   126篇
  2009年   155篇
  2008年   159篇
  2007年   162篇
  2006年   159篇
  2005年   146篇
  2004年   107篇
  2003年   126篇
  2002年   142篇
  2001年   122篇
  2000年   114篇
  1999年   95篇
  1998年   116篇
  1997年   93篇
  1996年   92篇
  1995年   61篇
  1994年   70篇
  1993年   67篇
  1992年   61篇
  1991年   56篇
  1990年   69篇
  1989年   99篇
  1988年   72篇
  1987年   70篇
  1986年   76篇
  1985年   52篇
  1984年   51篇
  1983年   41篇
  1982年   42篇
  1981年   35篇
  1980年   29篇
  1979年   27篇
  1977年   36篇
  1976年   31篇
  1975年   36篇
  1973年   38篇
  1972年   28篇
  1970年   32篇
排序方式: 共有4560条查询结果,搜索用时 31 毫秒
1.
In the United States, renal cell carcinoma (RCC) incidence and the prevalence of obesity, an established risk factor for RCC, have been increasing for several decades. RCC is more common among older individuals. We sought to quantify the contribution of excess adiposity to the rising incidence of RCC among individuals 60 years or older. National Institutes of Health-American Association of Retired Persons Diet and Health Study data (n = 453 859 participants, enrolled in 1995-1996, age at enrollment 50-71 years) were used to estimate multivariable-adjusted hazard ratios (HRs) for RCC across body mass index categories and HRs associated with smoking. Population attributable fractions (PAFs) were calculated using estimated HRs and annual overweight/obesity prevalence from the National Health Interview Survey (1985-2008). PAF estimates were combined with RCC incidence from Surveillance, Epidemiology and End Results-13 to calculate annual percent changes in RCC incidence attributable (and unrelated) to overweight/obesity. We found that between 1995 and 2018, among individuals aged 60 years and older, PAF for overweight/obesity increased from 18% to 29% for all RCCs. In comparison, the PAF for smoking declined from 12% to 9%. RCC incidence increased 1.8% per year (95% confidence interval [CI] 1.5%-2.1%) overall, while RCC incidence attributable to overweight/obesity increased 3.8% per year (95%CI 3.5%-4.2%) and RCC incidence unrelated to overweight/obesity increased 1.2% per year (95% CI 0.9%-1.4%). In conclusion, overweight/obesity appears to have contributed importantly to the rising incidence of RCC in the United States since the mid-1990s. Public health interventions focused on reducing overweight and obesity could help substantially in curbing this trend.  相似文献   
2.
According to the current nutritional recommendations issued by professional diabetes and nutrition associations, diabetic patients should keep to a diet consisting of 45–60% carbohydrates, 10–20% protein, and not more than 35% fat. However, not all of these nutritional recommendations are evidence based. For example, current studies show that the intake of insoluble roughage may be underrepresented. It is also possible that diabetic patients could benefit from keeping to the lower end of the recommended range for carbohydrates (45%) and the upper end of the range advised for protein (20%).  相似文献   
3.
BACKGROUND: Gastric cancer (GC) is the leading cause of cancer deaths in China. Our study prospectively evaluated the impact of repeated endoscopic screens on GC mortality in a high-risk population in China. METHODS: Between 1989 and 1999, a population-based gastroscopic screening was conducted in 4,394 residents of Linqu County, China, a region with the highest rates of GC worldwide. Residents ages 35 to 64 years received initial gastroscopies with biopsies in 1989. Repeated endoscopies were performed in 1994 and 1999. Cancer occurrences and deaths were actively monitored throughout the entire period until July 2000. Mortality from GC was compared with expected values based on mortality rates obtained for Linqu in the 1990-1992 Chinese Cancer Mortality Survey. RESULTS: Between March 1989 and July 2000, 39,303 person-years were accumulated; 85 new GCs occurred, 29 (34.5%) were in early stage. Fifty-eight cases (68%) were identified at one of the screens. The number of observed deaths from GC (37) was close to the expected (36.8). The standardized mortality ratio was 1.01 (95% CI 0.72-1.37) for the entire cohort, 1.13 (95% CI 0.77-1.57) for males, and 0.65 (95% CI 0.26-1.32) for females. CONCLUSIONS: Despite high population coverage with repeated screens, no reduction in GC mortality was observed in this high-risk population in China.  相似文献   
4.
The development of the artificial pancreas represents an important step forward in modern diabetology. The practical and theoretical findings obtained by its application to Type 1 (insulin-dependent) diabetic patients has given new insights into modes of insulin secretion, pathophysiology of diabetes mellitus, and new forms of treatment, i.e. the development of portable insulin pumps and intensified conventional insulin therapy. All of these therapies provided better results than conventional insulin administration. However, there is no doubt that the restoration of normoglycaemia in a real sense is obtainable only by an implantable artificial pancreas or pancreas transplantation. The development of the implantable artificial pancreas, on the other hand, is dependent upon the development of a reliably working permanently implantable glucose sensor. The first attempts in that direction have opened new vistas as to the differences between blood and interstitial tissue glucose measurements, displaying different modes of regulation under normal and pathologic conditions. A number of barriers have to be overcome until the final goal has been attained: to obtain, by automated blood glucose control, narrow glycaemic fluctuations of the normal subject, and to prevent, hopefully, relentless diabetic complications.  相似文献   
5.
Lipoprotein(a) as a strong indicator for cerebrovascular disease   总被引:19,自引:0,他引:19  
To evaluate the role of lipoprotein(a) (Lp(a] in patients with cerebrovascular disease (CVD), lipid parameters were compared with a control group (CO). Additionally, the Lp(a) serum levels were investigated in a coronary artery disease (CAD) group. The CO was made up of 37 healthy persons (age: 54.5 +/- 7.7, 26 males and 11 females), the CVD group included 46 patients with sustained transient ischemic attack (TIA) prolonged reversible ischemic neurologic deficits (PRIND) and cerebral infarction (CI) (age: 53.6 +/- 9.7, 32 males and 14 females), and the CAD group was made up of 28 survivors of myocardial infarctions (age: 52.5 +/- 8.1, 18 males and 10 females). The median values of Lp(a) in CVD were significantly higher than in the CO (p less than 0.01) and did not differ significantly from the CAD. Total TC, HDL-C, TG, LDL-C and the ratio of LDL-C/HDL-C did not show any significant difference between the control and cerebrovascular disease group. For quantification of the vascular lesions of the carotid system, a Duplex Doppler score system was used. The score correlated with Lp(a) in patients between 40 to 65 years of age (r = 0.34, p less than 0.01). Thus, we conclude that Lp(a) is not only a risk factor for CAD but also for CVD.  相似文献   
6.
Summary A randomized prospective study was performed to compare the results of filtering surgery using a Limbusbased versus a Fornix-based conjunctival flap. The wound closure of the Fornix-based flap was performed using a running 10/0 nylon suture at the limbus. No statistical significant difference of IOP regulation was found between the two groups. There was a tendency of reduced occurrence of shallow anterior chamber and of less vascularized filtering blebs in the Fornix-based technique.  相似文献   
7.
8.
目的 探讨创伤后迟发性脑肿胀的临床特点、发病机制与治疗。方法 回顾性分析1998年1月~2005年6月年收治的17例迟发性脑肿胀患者的临床特点和救治情况。结果 所有颅脑损伤患者采用保守治疗后均有好转,但于伤后5-10d出现恶化,CT复查有脑肿胀,经加强综合脱水等治疗后16例治愈,1例死亡。结论 迟发性脑肿胀好发于对冲性额、颞叶挫裂伤伴明显蛛网膜下腔出血、硬膜下薄层血肿及早期CT有脑肿胀者。其发病机制可能与创伤后的迟发性脑血管痉挛、微循环障碍、静脉回流障碍及甘露醇作用下降等因素有关。此类患者病情隐蔽性强,应加强观察、积极行CT复查,如能早期明确诊断,保守治疗多数效果良好。  相似文献   
9.
During the development of a silicone rubber implant for the delivery of estradiol 17-beta some batches of implants made from a certain lot of commercial estradiol inexplicably developed surface crystals of estradiol after several days of storage. An impurity profile was obtained for 28 lots of estradiol by a newly developed HPLC method. One or more impurities may have had a role in the spontaneous crystal growth on the surface of the implants, because the one lot of estradiol that initially had surface crystals on aging produced acceptable implants after multiple recrystallizations. Attempts to isolate suspected impurities for characterization were unsuccessful. During the manufacture of the implants, temperatures sufficient to melt the estradiol (mp, 173-179 degrees C) were used. It was expected that, upon implant cooling, melted impure estradiol would form a thermodynamically more active (i.e., noncrystalline) physical form. This metastable form could have migrated to the implant surface, where ambient conditions favored crystallization. Because melted estradiol of a higher purity tended to crystallize more readily, it was less likely to form a glass upon cooling. The phenomenon of surface crystallization was limited to one lot of estradiol with the highest level of impurities. Data from differential scanning calorimetry studies supported this conclusion.  相似文献   
10.
Thirteen patients with verified malignant mixed Müllerian tumor of the ovary treated in Denmark during the 7-year period 1981-87 were reviewed. Two patients had homologous and 11 patients had heterologous tumors. Four patients with early stage disease underwent radical surgery; 9 patients had stage III disease. Median survival for all 13 patients was 12 months. Six patients received platinum-containing cytotoxic therapy; 2 of these patients without measurable disease became long-term survivors (survival times 42+ and 92+ months, respectively) and 3 of the 4 remaining patients with evaluable disease obtained an objective remission.  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