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   8475篇
  免费   79篇
  国内免费   3篇
耳鼻咽喉   260篇
儿科学   42篇
妇产科学   143篇
基础医学   1013篇
口腔科学   284篇
临床医学   1640篇
内科学   886篇
皮肤病学   14篇
神经病学   118篇
特种医学   418篇
外科学   1943篇
综合类   15篇
预防医学   624篇
眼科学   161篇
药学   304篇
肿瘤学   692篇
  2024年   2篇
  2023年   11篇
  2021年   7篇
  2020年   5篇
  2019年   4篇
  2018年   17篇
  2017年   11篇
  2016年   10篇
  2015年   12篇
  2014年   18篇
  2013年   26篇
  2012年   320篇
  2011年   673篇
  2010年   330篇
  2009年   36篇
  2008年   482篇
  2007年   677篇
  2006年   691篇
  2005年   689篇
  2004年   807篇
  2003年   802篇
  2002年   867篇
  2001年   536篇
  2000年   734篇
  1999年   386篇
  1998年   128篇
  1997年   33篇
  1996年   37篇
  1995年   27篇
  1994年   21篇
  1993年   41篇
  1992年   3篇
  1991年   6篇
  1990年   6篇
  1989年   15篇
  1988年   8篇
  1987年   4篇
  1986年   11篇
  1985年   10篇
  1984年   8篇
  1983年   6篇
  1982年   10篇
  1981年   6篇
  1980年   10篇
  1978年   4篇
  1977年   3篇
  1976年   4篇
  1972年   3篇
排序方式: 共有8557条查询结果,搜索用时 562 毫秒
1.
BACKGROUND: Development of more than one primary melanoma in a patient is a relatively uncommon but well-recognized phenomenon. Its frequency has ranged from 1.2% to 8.2% in several series. This subgroup of patients with multiple primary lesions has not been characterized sufficiently. We report the experience of the Melanoma Unit of University Hospital Spedali Civili of Brescia, Italy. METHOD: Study subjects were drawn from 1240 patients with histologically confirmed melanoma, including melanoma in situ. From this group, multiple melanomas developed in 47 patients (3.79%). Every one of our patients has been taught to perform self-examination of the skin to detect suspicious pigmented lesions. RESULTS: Of the 47 patients described in this study, 38 had two primary melanomas, 7 had three melanomas and 2 had 5 and 10 melanomas, respectively. Mean age at first diagnosis was 46.2 years. The majority of subsequent melanomas (74.5%) were removed within 5 years of the initial operation. Synchronous lesions were found in 10 patients. In male patients, the lesion appeared most frequently on the trunk; in female patients, melanoma appeared mostly on the lower extremities. The second primary melanomas developed in the same anatomic region from the first in 53.2% of our patients. The proportion of in situ to invasive melanomas was greater for the second melanomas compared with the first melanomas. Regarding invasive melanomas, the mean thickness of the first melanomas was 1.31 mm compared with 0.66 mm for the second ones. Dividing patients into two groups, of more and less than 50, it is highlighted that in older patients synchronous lesions appear more frequently (36.4% vs. 8.0%); the median time interval between sequential melanomas is longer (84 vs. 63.7 months); and the ratio between the primary and secondary melanoma mean thickness is lower (1.21 : 1.08 vs. 1.43 : 0.63 mm). CONCLUSIONS: The study confirms that second primary melanoma is usually thinner than the first lesion, and it is more common in the same region of the body as the initial melanoma. The highest risk for a second melanoma is during the first 5 years, but a much longer time interval of 28 years is possible. Continued medical follow-up with complete skin examinations seems prudent, but it is very important to promote self-skin evaluation in patients to detect not only metastases but also subsequent primary melanomas in their earliest phases.  相似文献   
2.
59 angiomyolipomas were studied: immunohistochemistry (IHC) was used in 24 cases, electron microscopy (EM) in 6 cases. 57 tumors had a typical structure, 2 did not contain fat component. Premelanosomes were found by EM in one tumor. Smooth muscle actin was found in all tumor cells. Involvement of lymph nodes was observed in 2 patients. Histogenesis of this tumor is discussed.  相似文献   
3.
The aim of this work, that was carried out using Wistar rats, was to characterize the response of neurons of different morphofunctional types to amphetamine administration and to study the possibility of correction of these changes by delta-sleep inducing peptide (DSIP). Single intraperitoneal injection of 60 microg/kg of DSIP following a long term amphetamine administration (2.5 mg/kg for 3 weeks) was shown to result in normalization of brain metabolism, that was disturbed by the drug. The correcting DSIP effect was found in rat brain structures judging by the parameters of the state of proteins in neurons of sensomotor cortex and caudate nucleus and by the activity of enzymes of neurotransmitter metabolism, such as type A and B monoamine oxidases and acetylcholine esterase, that was determined in subfractions of the same brain structures. DSIP modulating effect in phenamine stereotypy supports its role as an adaptogen of intercenter relations in CNS pathology.  相似文献   
4.
Morphology of microparticles of the microencapsulated measles vaccine was studied by cryofractography, transmission electronic microscopy and by atomic force microscopy; co-polymers of polyacrylic acid and of sodium-alginate (spermidine) complexes were used as the matrix. The different-composition microcapsules had clear-cut borders and a certain range of sizes; but they were different in morphology, and their structures and densities varied identically with regard for a medium acidity, which is apparently preconditioned by some conformation-type alterations of matrix molecules. The studied preparations can, probably, protect the viral material in the stomach aggressive medium and release the material to ensure its contact with the intestine lymph tissue; thereof, they can be referred to as promising for further study of mucosal vaccines.  相似文献   
5.
The laboratory verified cases of Crimean-Congo hemorrhagic fever (CCHF) in the piedmont steppes of the North Caucasus (Malgobeksky District, Republic of Ingushetia) are first described. The source of the first infection was Ixodidae ticks; three subsequent sources were contacts with the bloody discharges from patients. CCHF virus genome was detected in the blood of the cattle from an epidemic focus and in the pools of the Ixodes ticks Haemaphysalis parva Neum., 1897 and Boophilus annulatus Say, 1821, taken from cattle. The problem of including the piedmont steppes of the North Caucasus into the CCHF nosological area is discussed.  相似文献   
6.
7.
8.
We report an instance of critical ovarian hyperstimulation syndrome in a highly responsive in-vitro fertilization patient despite the preventive measure of a 4 day 'coast' interval during which no gonadotrophins were administered while gonadotrophin-releasing hormone agonist therapy continued until serum oestradiol concentrations fell below 3000 pg/ml.   相似文献   
9.
The aim of this chronic experimental study performed in 16 dogs was to determine the effect of epidural infusion of 0.01% clopheline solution on the morphological and histoenzymological characteristics of spinal ganglion neurons. Daily infusions of clopheline at the dose of 15 mg/kg for 14 days caused a decrease in capillary permeability in the spinal ganglia at the injection site and its increase in the intact areas. This finding suggests the changes in the activity of the microcirculatory bed with a disturbed interaction in capillary-neuron system. Analysis of morphometric parameters has demonstrated the presence of some functional and reversible dystrophic changes in spinal ganglion neurons, which were associated with epidural infusion of both clopheline and isotonic solution of sodium chloride. Determination of the activity of oxidation-reduction enzymes, which reflect the course of aerobic and anaerobic processes in spinal ganglion neurons, has shown no significant differences between the groups of animals infused with or isotonic solution of sodium chloride. In conditions of chronic experiment no significant variations were found in RNA content in ganglionic cells at and outside the sites of infusion of clopheline and of isotonic solution of sodium chloride.  相似文献   
10.
We studied follow-up iliac mucosa biopsies from 11 patients with juvenile polyposis and 4 patients with familial adenomatous polyposis who had undergone total colectomy with mucosal proctoectomy with creation of straight ileoanal anastomosis. The biopsies that have been taken from the posterior wall of the terminal ileum show incomplete and focal neocolonic transformation of iliac mucosa. Nevertheless, in most cases iliac mucosa preserved its architectural and histochemical characteristics. Chronic inflammation in iliac mucosa is not typical for patients with polyposis.  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