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   6349篇
  免费   324篇
  国内免费   23篇
耳鼻咽喉   89篇
儿科学   168篇
妇产科学   92篇
基础医学   782篇
口腔科学   484篇
临床医学   540篇
内科学   1298篇
皮肤病学   108篇
神经病学   390篇
特种医学   59篇
外科学   521篇
综合类   58篇
一般理论   3篇
预防医学   1070篇
眼科学   92篇
药学   630篇
中国医学   95篇
肿瘤学   217篇
  2024年   6篇
  2023年   90篇
  2022年   249篇
  2021年   418篇
  2020年   220篇
  2019年   256篇
  2018年   261篇
  2017年   196篇
  2016年   198篇
  2015年   201篇
  2014年   329篇
  2013年   349篇
  2012年   480篇
  2011年   585篇
  2010年   254篇
  2009年   198篇
  2008年   322篇
  2007年   317篇
  2006年   293篇
  2005年   263篇
  2004年   237篇
  2003年   173篇
  2002年   160篇
  2001年   84篇
  2000年   68篇
  1999年   71篇
  1998年   35篇
  1997年   37篇
  1996年   19篇
  1995年   16篇
  1994年   17篇
  1993年   22篇
  1992年   26篇
  1991年   26篇
  1990年   26篇
  1989年   11篇
  1988年   23篇
  1987年   16篇
  1986年   12篇
  1985年   15篇
  1982年   7篇
  1980年   10篇
  1979年   8篇
  1977年   8篇
  1972年   7篇
  1971年   6篇
  1970年   5篇
  1969年   9篇
  1968年   8篇
  1967年   7篇
排序方式: 共有6696条查询结果,搜索用时 31 毫秒
1.
Coronavirus disease-19 (COVID-19) caused by the severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) is now a pandemic threat. This virus is supposed to be spread by human to human transmission. Cellular angiotensin-converting enzyme 2 (ACE2) is the receptor of SARS-CoV-2 which is identical or similar in different species of animals such as pigs, ferrets, cats, orangutans, monkeys, and humans. Moreover, a recent study predicted that dogs might be secondary hosts during the evolution of SARS-CoV-2 from bat to human. Therefore, there is a possibility of spreading SARS-CoV-2 through domestic pets. There are now many reports of SARS-CoV-2 positive cases in dogs, cats, tigers, lion, and minks. Experimental data showed ferrets and cats are highly susceptible to SARS-CoV-2 as infected by virus inoculation and can transmit the virus directly or indirectly by droplets or airborne routes. Based on these natural infection reports and experimental data, whether the pets are responsible for SARS-CoV-2 spread to humans; needs to be deeply investigated. Humans showing clinical symptoms of respiratory infections have been undergoing for the COVID-19 diagnostic test but many infected people and few pets confirmed with SARS-CoV-2 remained asymptomatic. In this review, we summarize the natural cases of SARS-CoV-2 in animals with the latest researches conducted in this field. This review will be helpful to think insights of SARS-CoV-2 transmissions, spread, and demand for seroprevalence studies, especially in companion animals.  相似文献   
2.
3.
Melatonin, the main hormone produced by the pineal gland, is secreted in a circadian manner (24‐hr period), and its oscillation influences several circadian biological rhythms, such as the regulation of clock genes expression (chronobiotic effect) and the modulation of several endocrine functions in peripheral tissues. Assuming that the circadian synchronization of clock genes can play a role in the regulation of energy metabolism and it is influenced by melatonin, our study was designed to assess possible alterations as a consequence of melatonin absence on the circadian expression of clock genes in the epididymal adipose tissue of male Wistar rats and the possible metabolic repercussions to this tissue. Our data show that pinealectomy indeed has impacts on molecular events: it abolishes the daily pattern of the expression of Clock, Per2, and Cry1 clock genes and Pparγ expression, significantly increases the amplitude of daily expression of Rev‐erbα, and affects the pattern of and impairs adipokine production, leading to a decrease in leptin levels. However, regarding some metabolic aspects of adipocyte functions, such as its ability to synthesize triacylglycerols from glucose along 24 hr, was not compromised by pinealectomy, although the daily profile of the lipogenic enzymes expression (ATP‐citrate lyase, malic enzyme, fatty acid synthase, and glucose‐6‐phosphate dehydrogenase) was abolished in pinealectomized animals.  相似文献   
4.
The outbreaks of rabies in humans transmitted by Desmodus rotundus in 2004 and 2005, in the northeast of the Brazilian State of Para, eastern Amazon basin, made this a priority area for studies on this zoonosis. Given this, the present study provides data on this phenomenon in an urban context, in order to assess the possible circulation of the classic rabies virus (RABV) among bat species in Capanema, a town in the Amazon basin. Bats were collected, in 2011, with mist nets during the wet and dry seasons. Samples of brain tissue and blood were collected for virological and serological survey, respectively. None of the 153 brain tissue samples analyzed tested positive for RABV infection, but 50.34% (95% CI: 45.67-55.01%) of the serum samples analyzed were seropositive. Artibeus planirostris was the most common species, with a high percentage of seropositive individuals (52.46%, 95% CI: 52.31 52.60%). Statistically, equal proportions of seropositive results were obtained in the rainy and dry seasons (c2 = 0.057, d.f. = 1, p = 0.88). Significantly higher proportions of males (55.96%, 95% CI: 48.96-62.96%) and adults (52.37%, 95% CI: 47.35-57.39%) were seropositive. While none of the brain tissue samples tested positive for infection, the high proportion of seropositive specimens indicates that RABV may be widespread in this urban area.  相似文献   
5.
The aim of the study was to explore the relationship between college graduates’ dual self-consciousness, job search clarity and perceived stress, and reveal the mediating role of perceived stress between dual self-consciousness and job search clarity. In this study, 467 college graduates were investigated using the Dual Self-Consciousness Scale, Job Search Clarity Scale, and Perceived Stress Scale. After controlling for gender, age, and region, the results revealed that: (1) private self-consciousness has a significant positive predictive effect on job search clarity; (2) perceived stress has a significant negative predictive effect on job search clarity; (3) perceived stress plays partial mediation effects between private self-consciousness and job search clarity; (4) perceived stress plays complete mediation effects between public self-consciousness and job search clarity; (5) perceived stress has suppressing effects between public self-consciousness and job search clarity.  相似文献   
6.
7.
We report on 3 patients with pseudoathetosis, which are involuntary, slow, writhing movements due to loss of proprioception.  相似文献   
8.
BACKGROUND: Randomized studies demonstrate that laparoscopic appendectomy yields better results compared with open techniques. We sought to identify factors that determine an extended hospital stay among patients undergoing laparoscopic appendectomy. METHODS: This was a prospective study including 669 patients undergoing laparoscopic appendectomy. We analyzed variables that can predict the length of hospital stay. RESULTS: Of 669 patients undergoing laparoscopic appendectomy, 141 stayed in the hospital for > or = 5 days (Group 1), and 97 stayed in the hospital for < or = 1 day after surgery (Group 2). The univariate analysis demonstrated that fever (P<0.0001), nausea and vomiting (P=0.060), leukocytosis (P<0.0001), gangrened or perforated intraoperative appearance of the appendix (P<0.0001), and appendix position behind the ileocecal junction (P<0.001) were related to a longer hospital stay. The multivariate analysis through logistical regression showed that the factors independently and significantly associated with an extended hospital stay were presurgical fever, appendix position behind the ileocecal junction, and intraoperative gangrened or perforated appearance of the appendix. CONCLUSION: Fever, appearance, and position of the appendix are factors related to an extended hospital stay.  相似文献   
9.
An interesting case of a child with a tail is reported. The child had a tail like structure in the back since birth, increasing with age. It was 20 cm. long, the longest tail so far described in the English literature. There was no functional complain. The result was excellent after excision as the problem was only cosmetic.  相似文献   
10.
The anatomic response to intravitreal bevacizumab injection in three patients with aggressive, posterior retinopathy of prematurity is described. In all cases, the worse eye was treated with a single intravitreal injection of 0.75 mg of bevacizumab as monotherapy or complementary to laser therapy. In 24 hours, all injected eyes showed regression of the tunica vasculosa lentis and iris vessel engorgement and disappearance of iris rigidity. In addition, plus disease and retinal proliferation began to regress. None of the eyes required additional treatment. Follow-up of up to 10 months  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