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   6533篇
  免费   290篇
  国内免费   51篇
耳鼻咽喉   135篇
儿科学   133篇
妇产科学   281篇
基础医学   851篇
口腔科学   52篇
临床医学   629篇
内科学   1935篇
皮肤病学   63篇
神经病学   617篇
特种医学   114篇
外科学   745篇
综合类   47篇
一般理论   1篇
预防医学   268篇
眼科学   111篇
药学   514篇
中国医学   12篇
肿瘤学   366篇
  2023年   35篇
  2022年   176篇
  2021年   304篇
  2020年   95篇
  2019年   140篇
  2018年   153篇
  2017年   105篇
  2016年   124篇
  2015年   147篇
  2014年   238篇
  2013年   280篇
  2012年   483篇
  2011年   483篇
  2010年   260篇
  2009年   214篇
  2008年   393篇
  2007年   461篇
  2006年   469篇
  2005年   444篇
  2004年   426篇
  2003年   420篇
  2002年   369篇
  2001年   60篇
  2000年   44篇
  1999年   53篇
  1998年   43篇
  1997年   52篇
  1996年   47篇
  1995年   17篇
  1994年   27篇
  1993年   15篇
  1992年   24篇
  1991年   22篇
  1990年   26篇
  1989年   28篇
  1988年   26篇
  1987年   11篇
  1986年   15篇
  1985年   12篇
  1984年   11篇
  1983年   11篇
  1982年   10篇
  1981年   10篇
  1980年   7篇
  1979年   7篇
  1978年   7篇
  1977年   9篇
  1970年   8篇
  1969年   8篇
  1966年   7篇
排序方式: 共有6874条查询结果,搜索用时 10 毫秒
61.
Pregnancy offers a unique opportunity for the early diagnosis of cervical cancer, due to the fact that pregnant patients have many possibilities of gynecological and cytological examinations. There is much evidence that pregnant women have two to three-fold higher chance of having preneoplastic lesions and early, operable stages of disease diagnosed. The preneoplastic lesions do not require any intervention during pregnancy. However, precise, serial colposcopic examinations, completed by biopsy if necessary, must be seriously considered in order to exclude invasive cancer. The only indication for conization during pregnancy is to rule out or confirm microinvasive or invasive cancer, provided such diagnose can change the time and the way of delivery. Invasive cervical cancer diagnose is frequently associated with difficult medical and ethical decisions. The most proper approach should be considered, taking into account the benefit of the mother and the child. The decision is easier in the early stage of cancer, because it has been proven that six- to twelve-week delay of the beginning of the therapy does not deteriorate the cancer outcome but it enables the fetus to acquire sufficient lung maturity. Advanced carcinoma of the cervix forces us to take prompt therapeutic decisions. Both, the continuation of the pregnancy and the administration of neoadjuvant chemotherapy are still possible.  相似文献   
62.
Mediastinal emphysema and subcutaneous emphysema are rare complications of labor. We have described a case of mediastinal and subcutaneous emphysema, observed in the II stage of labor in otherwise healthy primigravida. The diagnosis was confirmed clinically and by X-ray, and endoscopies examination in District Hospital and in Clinical Department of Surgery. The etiology of this condition was not established. The mediastinal and subcutaneous emphysema, disappeared spontaneously which was confirmed by check-up after 3 months.  相似文献   
63.
OBJECTIVE: Well-known natural unspecific antimicrobial factors acting in the vagina are additionally reinforced during menstrual bleeding by hemocidins--a recently discovered novel class of microbicidal peptides generated proteolytically from hemoglobin. The aim of the presented research was to investigate the relation between the average length of menstrual bleeding and the frequency of urogenital infections. We expected that the shorter menstrual bleeding might increase the risk of urogenital infections because is synonymous with the shorter period of exposition on bactericidal action of hemocidins. STUDY DESIGN: The study contains statistical analysis of an average declared length of menstrual bleeding in the group of 267 young, sexually active women with the symptoms of urogenital infections. The control group consisted of 300 young healthy women. RESULTS: The length of menstrual bleeding in the group of patients with urogenital infections (average 4.35 days) was statistically significantly shorter than in the control group (average 4.95 days). The average length of the menstrual cycle was equal and counted ca. 28 days in both groups. CONCLUSION: The length of menstrual bleeding seems to be a significant factor in the vaginal ecology maintenance.  相似文献   
64.
The process of foaming poly(caprolactone)-based composite materials using supercritical carbon dioxide was analyzed, especially in terms of the biocompatibility of the resultant materials. The influence of foaming process conditions and composite material properties on the functional properties of polymer solid foams, intended for artificial scaffolds for bone cell culture, was investigated. The relationship between wettability (contact angle) and water absorption rate as a result of the application of variable conditions for the production of porous structures was presented. For the evaluation of potential cytotoxicity, the MTT and PrestoBlue tests were carried out, and animal cells (mouse fibroblasts) were cultured on the materials for nine days. There was no toxic effect of composite materials made of poly(caprolactone) containing porogen particles: hydroxyapatite, crystalline nanocellulose, and graphene oxide on cells. The desired effect of the porogens used in the foaming process on the affinity of cells to the resultant material was demonstrated. The tested materials have been shown to be biocompatible and suitable for applications in biomedical engineering.  相似文献   
65.
Glulam beams are increasingly used in the construction industry because of their high strength and the possibility of using round timber with smaller cross-sections. The load-bearing capacity of beams is strongly related to the quality of the outer layers and, in the case of wood, especially the tension zones. For these reasons, this study decided to replace the outer lamella with tensile plywood. The produced beams were subjected to static bending strength and modulus of elasticity evaluation. It was shown that the best static bending strength values were obtained for beams containing plywood in the tension layer. However, the change in structure in the tension zone of beams made of glued laminated timber results not only in an increase in the load capacity of elements produced in this way but also in a decrease in the range/range of the obtained results of bending strength. This way of modifying the construction of glued laminated beams allows a more rational use of available pine timber.  相似文献   
66.
BackgroundPlatelets play a vital role in the neoplastic process. Platelet parameters are hence an important source of information concerning ongoing neoplastic disease. The aim of the study is to assess the impact of selected platelet parameters on the survival of patients with non-small cell lung cancer (NSCLC).MethodsThe study included 532 (174 female and 358 male) patients aged 36–84 years (mean age 63.6 years) operated on due to NSCLC, staged IA–IIIA. Before the operation, all patients received a blood morphology test. The following parameters were subjected to statistical analysis: platelet count, mean platelet volume (MPV) parameter, platelet distribution width (PDW) parameter, platelet-to-lymphocyte ratio (PLR) and systemic immune-inflammation (SII) index. These findings were compared with the clinical data of the patients, and the probability of overall survival was analyzed.ResultsThe univariate analysis revealed a correspondence between PDW, MPV, PLR and SII index and patient survival. The multivariate analysis including patient clinical data found the following factors to have negative prognostic value for patients operated on due to NSCLC: male sex, advancement stage of neoplastic disease and Charlson Comorbidity Index (CCI) above 4, and PLR >144.ConclusionsPDW value, PLR and SII index are independent prognostic factors. In the multi-factor model, male sex, the advancement stage of the neoplastic disease, CCI above 4 and PLR lower than 144 had the greatest prognostic value.  相似文献   
67.
Nematodes as bioindicators of soil degradation due to heavy metals   总被引:1,自引:0,他引:1  
The effect of distance from a heavy metal pollution source on the soil nematode community was investigated on four sampling sites along an 4?km transect originating at the Kovohuty a.s. Krompachy (pollution source). The soil nematode communities were exposed to heavy metal influence directly and through soil properties changes. We quantified the relative effects of total and mobile fraction of metals (As, Cd, Cr, Cu, Pb, and Zn) on soil ecosystem using the nematode community structure (trophic and c-p groups,) and ecological indices (Richness of genera, H′, MI2-5, etc.). Pollution effects on the community structure of soil free living nematodes was found to be the highest near the pollution source, with relatively low population density and domination of insensitive taxa. A decrease in heavy metals contents along the transect was linked with an increase in complexity of nematode community. The majority of used indices (MI2-5, SI, H′) negatively correlated (P?<?0.05 or P?<?0.01) with heavy metals content and were sensitive to soil ecosystem disturbance. Contamination by heavy metals has negatively affected the soil environment, which resulted in nematode community structure and ecological indices changes. Results showed that the free-living nematodes are useful tools for bioindication of contamination and could be used as an alternative to the common approaches based on chemical methods.  相似文献   
68.
69.
70.
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