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   2351篇
  免费   146篇
  国内免费   26篇
耳鼻咽喉   26篇
儿科学   66篇
妇产科学   56篇
基础医学   303篇
口腔科学   57篇
临床医学   145篇
内科学   711篇
皮肤病学   48篇
神经病学   199篇
特种医学   21篇
外科学   371篇
综合类   13篇
预防医学   159篇
眼科学   45篇
药学   130篇
中国医学   22篇
肿瘤学   151篇
  2023年   19篇
  2022年   47篇
  2021年   59篇
  2020年   46篇
  2019年   50篇
  2018年   67篇
  2017年   38篇
  2016年   60篇
  2015年   71篇
  2014年   94篇
  2013年   103篇
  2012年   161篇
  2011年   181篇
  2010年   109篇
  2009年   91篇
  2008年   146篇
  2007年   172篇
  2006年   139篇
  2005年   137篇
  2004年   154篇
  2003年   125篇
  2002年   128篇
  2001年   27篇
  2000年   29篇
  1999年   26篇
  1998年   23篇
  1997年   14篇
  1996年   12篇
  1995年   20篇
  1994年   10篇
  1993年   6篇
  1992年   7篇
  1991年   16篇
  1990年   5篇
  1989年   11篇
  1988年   7篇
  1987年   9篇
  1986年   8篇
  1985年   8篇
  1984年   5篇
  1983年   7篇
  1981年   5篇
  1979年   8篇
  1978年   6篇
  1977年   6篇
  1975年   6篇
  1974年   4篇
  1971年   4篇
  1963年   4篇
  1958年   3篇
排序方式: 共有2523条查询结果,搜索用时 15 毫秒
1.
2.
Although renal dysfunction is common after liver transplantation, postoperative renal function after split liver transplantation (SLT) has not been well studied. Renal function immediately after surgery was analyzed retrospectively in 16 patients that received a SLT (SLT group). The results were compared with corresponding data from 31 matched patients that received a full-size liver transplant (FSLT group) during the same period. Serum creatinine (SCr) was measured before surgery, and, after transplantation, daily during the first week and at days 14, 21, and 28. Renal dysfunction (RD) was defined as the requirement for renal replacement therapy (RRT) or a 100% increase in SCr if the basal value had been <1.0 mg/dL or a 50% increase in SCr if the basal value had been >1.0 mg/dL. SCr had to be at least 1.5 mg/dL for a diagnosis of RD to be considered. The classification of RD was: mild, SCr 1.5-2.4 mg/dL; moderate, SCr 2.5-4.0 mg/dL; or severe, SCr >4.0 mg/dL (the requirement for RRT). Both donor and recipient age and cold ischemia time were lower in the SLT group than in the FSLT group (P < 0.05). Length of surgery was longer in the SLT group (P < 0.05). There were no significant differences between groups with respect to Model for End-Stage Liver Disease scores, the need for transfusions, the length of admission to the intensive care unit (ICU), survival rate, individual severity index, or sepsis-related organ failure assessment scores at the time of diagnosing RD. Immunosuppression regimens were similar in both groups. RD developed in 82% of SLT patients, but in only 58% of FSLT patients (P = not significant [NS]). Among SLT patients, RD (23.0% mild, 15.5% moderate, and 61.5% severe) was more severe (P = 0.007) than in FSLT patients (63.1% mild, 15.8% moderate, and 24.1% severe). The requirement for RRT in the SLT group (43.7%) was significantly greater (P < 0.05) than that in the FSLT group (12.9%). This finding may be due to the different incidence of sepsis in the 2 groups (SLT 37.5% vs. FSLT 9.7%; P < 0.05). In conclusion, although the number of patients studied was small, our data suggest a higher incidence of RD and a greater requirement for RRT in patients that receive a split liver graft than in those that receive a full size liver graft.  相似文献   
3.
The aim of this series of experiments was to determine whether attention is normally required for continuously processing vestibular information concerning orientation, or is required only when orientation is disrupted (eg by vestibular dysfunction or by conflicting visual and vestibular orientation cues). In the first two studies, healthy subjects were passively oscillated, and indicated when they perceived they were passing through their starting position. There was only weak evidence for interference between performance on this 'continuous orientation monitoring task' and on concurrent mental tasks. However, a third study showed that when patients with vestibular imbalance carried out the continuous orientation monitoring task their performance on a concurrent mental arithmetic task was substantially impaired. This dual task interference was correlated with inaccuracy in judging orientation on the continuous orientation monitoring task, which in turn correlated with severity of recent vestibular symptomatology (assessed by questionnaire). In a fourth experiment, disorientation was induced in healthy subjects by rotating the visual field about the line of sight. Bidirectional interference was observed between monitoring orientation (assessed by accuracy in setting a rod to the perceived vertical) and performance of an arithmetic task. Dual task interference was correlated with baseline levels of disorientation induced by the visual field, as indicated by inaccuracy in judging the visual vertical. These findings suggest that monitoring orientation makes significant demands upon cortical processing resources when disorientation is induced, whether the disorientation results from deficient sensory functioning or from ambiguous perceptual information.  相似文献   
4.
An extensive field survey allowed us to expand the geographical distribution of the scorpion Tityus perijanensis in the Perijá range, western Zulia State, Venezuela, including areas where adult cases of severe scorpionism have been reported. 16S ribosomal RNA (rRNA) gene sequencing, DL(50) determination, and native PAGE suggest low genetic and venom proteomic divergence across the distribution range. The results also indicate phylogenetic divergence between T. perijanensis and T. discrepans, the species prevalent in northcentral Venezuela. T. perijanensis venom lethality (0.91-0.94 mg/kg) is comparable to that of the Brazilian T. serrulatus and ranks highest among toxic Venezuelan Tityus studied so far. The data indicate that the Perijá range should be included amongst the endemic areas of scorpionism of Venezuela and Colombia.  相似文献   
5.
About 85% of the population of two Somali communities harboured soil-transmitted intestinal nematodes and/or protozoa. The commonest parasite (75% in the Lafoole institution and 59% in the Afgoye institution) was Trichuris trichiura. Mixed infections were common. The source of infection is contaminated fields around dwelling quarters, because of indiscriminate defaecation. One of the factors responsible for the higher incidence of hookworm in Lafoole (45%) compared with Afgoye (1.5%) may be the different soil character of the surrounding fields.  相似文献   
6.
7.
The chain propagation rate constants for the polymerization of ethylene and propene in the presence of δ-TiCl3/Al(CH3)3 at 22 °C are determined by means of a 13C NMR analysis of suitable block copolymers. The numerical values of the rate constants are compared with those previously reported.  相似文献   
8.
Gastric mucormycosis involvement is a rare condition that usually occurs in inmunocompromised patients and frequently has a fatal outcome. We report the case of a 73‐year‐old woman admitted to the intensive care unit with severe bleeding after an acute pulmonary disease. Upper endoscopy disclosed wide and deep necrotic ulcers in the body and fundus of the stomach and greenish exudates with the antrum and the duodenum undamaged. Autopsy revealed an invasive mucormycosis and a severe atheromatosis. Several predisposing factors for mucormycosis infection have been reported until now. We postulate that ischemic gastritis could be a predisposing factor for colonization of zygomycete.  相似文献   
9.
Colorectal cancer is one of the most common malignancies in developed countries. Although guaiac-based fecal occult blood tests have proven their efficacy for screening, they have major drawbacks. Immunochemical fecal occult blood tests are theoretically superior as they can detect very small amounts of hemoglobin, and they are specific to human hemoglobin. Recently many different immunochemical tests have been marketed, with variations in hemoglobin detection limit, mechanism of action, sample collection method, and test development. Molecular tests represent an alternative to fecal blood tests, which have been designed to detect certain fecal DNA mutations, or aberrant gene methylation (either hyper-or hypomethylation). In this review, we discuss a selection of the most significant studies published in the last 3 years regarding noninvasive tools for colorectal cancer screening.  相似文献   
10.
The authors present a retrospective study concerning 135 cases of untreated synchronous metastases from colorectal cancer. The median survival is 5.5 months and the natural history is depending on the percentage of liver replacement, on the "performance status" of each patient and on the stage of primary tumors classified according to Dukes. The seric levels of Alkaline Phosphatase and CEA are other useful prognostic factors. The age of patients and systemic chemotherapy (5-Fluorouracil) are not able to influence the evolution of the disease. At last different techniques, both curative and palliative, used in the current treatment of liver metastases from colorectal cancer are discussed and the reported survival improvements reaching with these forms of treatment are compared to the natural history of the disease.  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