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   29722篇
  免费   2375篇
  国内免费   40篇
耳鼻咽喉   346篇
儿科学   1092篇
妇产科学   717篇
基础医学   5083篇
口腔科学   627篇
临床医学   2772篇
内科学   5785篇
皮肤病学   407篇
神经病学   3004篇
特种医学   1302篇
外国民族医学   8篇
外科学   3134篇
综合类   218篇
一般理论   12篇
预防医学   3039篇
眼科学   415篇
药学   1979篇
中国医学   25篇
肿瘤学   2172篇
  2023年   136篇
  2022年   248篇
  2021年   485篇
  2020年   334篇
  2019年   473篇
  2018年   601篇
  2017年   504篇
  2016年   549篇
  2015年   644篇
  2014年   824篇
  2013年   1173篇
  2012年   1704篇
  2011年   1774篇
  2010年   870篇
  2009年   934篇
  2008年   1488篇
  2007年   1504篇
  2006年   1487篇
  2005年   1407篇
  2004年   1218篇
  2003年   1199篇
  2002年   1061篇
  2001年   978篇
  2000年   976篇
  1999年   915篇
  1998年   423篇
  1997年   373篇
  1996年   360篇
  1995年   319篇
  1994年   308篇
  1993年   266篇
  1992年   593篇
  1991年   586篇
  1990年   553篇
  1989年   544篇
  1988年   479篇
  1987年   417篇
  1986年   379篇
  1985年   366篇
  1984年   277篇
  1983年   227篇
  1982年   130篇
  1981年   154篇
  1979年   170篇
  1978年   120篇
  1977年   131篇
  1976年   113篇
  1975年   117篇
  1974年   150篇
  1973年   106篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
With a view to the development of new controlled drug delivery systems, the formation of an interpolyelectrolyte complex (IPEC) between chitosan (CTS) and Eudragit L100 (L-100) has been studied. The structure of this IPEC is such that two maxima are observed in the curves of IPEC swelling in the media with different pH values. The release of a model drug (ibuprofen) from IPEC-based tablets is significantly retarded, and this delay can be controlled by changing the molecular weight of CTS in the IPEC composition. __________ Translated from Khimiko-Farmatsevticheskii Zhurnal, Vol. 39, No. 12, pp. 44–46, December, 2005.  相似文献   
32.
ObjectivesTo evaluate and summarize the evidence linking balance impairment as a risk factor for falls in community-dwelling older adults.Study Design and SettingSystematic review and meta-analysis. English language articles in MEDLINE, EMBASE, CINAHL (1988–2009), under keywords of accidental falls, aged, risk factors, and hip, radius, ulna, and humerus fractures; and bibliographies of retrieved articles. Community-dwelling older adults in a prospective study, at least 1-year duration, age more than 60 years, and samples not specific to a single disease-defined population were included. Sample size, inclusion/exclusion criteria, demographics, clinical balance measurement scale, type of fall outcome, method of fall ascertainment, length of follow-up, and odds ratio (OR) or risk ratio (RR) were extracted. Studies must have reported adjustment for confounders. Random effects meta-analysis to generate summary risk estimate was used. A priori evaluation of sources of heterogeneity was performed.ResultsTwenty-three studies met the selection criteria. A single summary measure could not be calculated because of the nonequivalence of the OR and RR, producing an overall fall risk of RR of 1.42 (1.08, 1.85) and OR of 1.98 (1.60, 2.46).ConclusionsBalance impairment imparts a moderate increase on fall risk in community-dwelling older adults. The type of fall outcome, the length of follow-up, and the balance measurement tool impact the magnitude of the association. Specific balance measurement scales were identified with associations for an increased fall risk, but further research is required to refine recommendations for their use in clinical practice.  相似文献   
33.
OBJECTIVE: To determine whether inhaled corticosteroids should be prescribed to patients with milder forms of asthma and whether markers of airway inflammation should be considered when making therapy decisions. DATA SOURCES: A PubMed search was performed of the English-language literature published in the preceding 10 years (January 1, 1993, through December 31, 2003) concerning epidemiology, pathophysiology, therapy, and prognosis of mild intermittent asthma, with asthma, mild, and intermittent as indexing terms. STUDY SELECTION: All relevant studies including author's expert opinions were selected. RESULTS: Several studies have addressed the question of a possible benefit of maintenance therapy (ie, inhaled steroids) in patients with mild intermittent asthma. Although a diminishing effect on airway inflammation has been widely demonstrated, even in patients with mild disease, the impact of inhaled steroids on the long-term prognosis is much less clear. For patients with mild disease who are long-term inhaled steroid users, alternative therapy strategies, including low-dose inhaled steroids and leukotriene receptor antagonists, have been advocated. CONCLUSIONS: Mild intermittent asthma is a disease characterized not only by infrequent symptoms and normal lung function but also by chronic airway inflammation, possibly resulting in irreversible airflow limitation if left unattended. Therefore, maintenance therapy, such as (low-dose) inhaled steroids or leukotriene receptor antagonists, should be considered in patients with mild disease. Future studies should give more insight into the impact of prolonged anti-inflammatory therapy on the long-term prognosis of mild intermittent asthma patients. Whether results from these studies will justify a more aggressive treatment for these patients remains to be answered.  相似文献   
34.
AIM: To gain insight into the impact of urinary incontinence on the daily lives of Moroccan and Turkish women and their preferences for treatment. DESIGN OF STUDY: A qualitative analysis of data from semi-structured in depth interviews with 30 Moroccan and Turkish migrant women with urinary incontinence. SETTING: Six general practices with large numbers of immigrant families in four cities in the Netherlands. METHOD: Semi-structured in depth interviews were conducted with Moroccan and Turkish migrant women, who presented with complaints of urinary incontinence in six general practices with large numbers of immigrant families on the practice list in four different cities in the Netherlands. RESULTS: All the women adhered closely to bodily cleanliness and considered incontinence to be dirty. As Muslims, they were obliged to perform ritual prayers preceded by ablution five times per day and the urinary incontinence breached their status of ritual purity. Therefore, they had to wash more often and experienced this as a heavy burden. In a number of the women, shame formed a reason why they could not talk to anybody about the incontinence, not even with the doctor. One-third of the women felt that their GP had not taken them seriously. Knowledge about anatomy, physiology and available treatments was mostly lacking. In addition, the women did not understand the aim of the exercises from the physiotherapist. The majority of women gave preference to help from a female doctor. CONCLUSION: Urinary incontinence in Moroccan and Turkish migrant women formed a considerable problem in their daily following of the Islam faith. Shame on the part of the patient and miscommunication at the doctor's surgery led to inadequate care.  相似文献   
35.
BACKGROUND: Pre-clinical and clinical studies suggest that transplantation of bone marrow-derived stem cells can improve global cardiac function. However, no quantitative assessment of regional systolic contraction and correlation with phenotype has been made. Therefore, we used our model of cryoinfarcted rabbit myocardium for intracardiac transplantation of a mixed population of bone marrow-derived cells and assessed both regional function and myogenic conversion of the cells. METHODS: Nineteen New Zealand white rabbits underwent cryoinjury of the left ventricle. Autologous bone marrow (BM) cells were expanded in vitro. After 2 weeks, either 1 x 10(8) mixed BM-derived progenitor cells (BM group, n = 11) or vehicle (control group, n = 8) were injected into the cryoinjured region. Regional systolic function was measured using micromanometry and sonomicrometry before and 4 weeks after cell injection; cell phenotype was evaluated histologically. RESULTS: All animals in the BM group significantly improved both systolic shortening (0.11 +/- 0.7 vs -0.05 +/- 0.05 mm in the control group, p < 0.05) and regional stroke work when compared with control (9.6 +/- 2.4 vs -1.2 +/- 1.2 mm . mm Hg, p < 0.003). In addition, the BM group had improved global diastolic function, as measured by minimum dP/dt and end-diastolic pressure. On histologic assessment, BM cells differentiated toward a myogenic phenotype. CONCLUSIONS: Transplanting a mixed population of marrow-derived cells that can adopt a myogenic phenotype improves regional contractility and diastolic relaxation after myocardial infarction.  相似文献   
36.
The original article to which this Erratum refers was published in Pharmacoepidemiology and Drug Safety 2005; 14: 239–247.  相似文献   
37.
Kollicoat IR, a new pharmaceutical excipient developed as a coating polymer for instant release tablets, was evaluated as a carrier in solid dispersions of Itraconazole. The solid dispersions were prepared by hot stage extrusion. Modulated temperature differential scanning calorimetry and X-ray powder diffraction were used to evaluate the miscibility of the drug and the carrier. The pharmaceutical performance was evaluated by dissolution experiments, performed in simulated gastric fluid without pepsin (SGF(sp)). In the X-ray diffractograms no Itraconazole peaks were visible; the polymer on the other hand appeared to be semi-crystalline. Moreover, its crystallinity increased during the extrusion process due to exposure to heat and shear forces. Modulated temperature differential scanning calorimetry analysis showed that the drug and the polymer formed a two phase system. Separate clusters of glassy Itraconazole were present for drug loads of 40% or higher, indicating further phase separation. Dissolution measurements demonstrated a significantly increased dissolution rate for the solid dispersions compared to physical mixtures. Interestingly the physical mixture made up of glassy Itraconazole and Kollicoat IR (20/80, w/w) showed a dissolution rate and maximum that was much higher than that of the physical mixture made up of crystalline Itraconazole and that of pure glassy Itraconazole. The results of this study show that Kollicoat IR is a promising excipient for the formulation of solid dispersions of Itraconazole prepared by hot stage extrusion.  相似文献   
38.
Risk Factors for a First Febrile Seizure: A Matched Case-Control Study   总被引:10,自引:6,他引:4  
Summary We conducted a matched casecontrol study to identify risk factors for first febrile seizures, with special emphasis on characteristics of the acute illness episode. Cases were identified through hospital emergency departments; controls were identified through outpatient clinics and emergency departments. Sixtynine children with first febrile seizures and no history of previous unprovoked seizures were matched for age (±6 months), site of routine pediatric care, and date of visit (±weeks) with 1 or 2 febrile controls who had no history of previous febrile or unprovoked seizures. Medical records for the index visit were reviewed, and parents were interviewed by telephone. Illness characteristics examined included height of temperature, type of underlying illness, contact with a physician during the illness but before the index visit, and use of acetaminophen or decongestants. Family history of febrile and of unprovoked seizures, sociodemographic characteristics, daycare use, and selected preand perinatal variables were also studied. On multivariable analysis, significant independent risk factors were height of temperature, history of febrile seizures in a firstor in a higher degree relative. Gastroenteritis as the underlying illness had a significant inverse (i.e., protective) association with febrile seizures. Maternal smoking during pregnancy was a marginally significant predictor of febrile seizures.  相似文献   
39.
Roth  J; Burwinkel  F; van den Bos  C; Goebeler  M; Vollmer  E; Sorg  C 《Blood》1993,82(6):1875-1883
MRP8 and MRP14 are two Ca(2+)-binding proteins of the S-100 family expressed by myelomonocytic cells. Both proteins assemble to noncovalently associated complexes in a Ca(2+)-dependent manner. Members of the S-100 family are known to play a role in cytoskeletal- membrane interactions; therefore, we investigated the subcellular distribution of MRP8/MRP14 and their complexes in human monocytes. Using differential centrifugation and subsequent Western blot or enzyme- linked immunosorbent assay analysis, we found that MRP8/MRP14 were almost completely translocated from the cytoplasma to membrane and cytoskeletal structures in a Ca(2+)-dependent manner. Using a cross- linking technique, complexed forms of MRP8/MRP14 were found to be associated with the plasma membrane. Analysis of MRP-transfected L132 cells showed that the MRP8 as well as the MRP14 component of the MRP8/MRP14 complex may independently bind to membrane and cytoskeletal structures. Furthermore, immunogold electron microscopy showed a colocalization of MRP8/MRP14 and the intermediate filament type III protein vimentin in A23187-treated monocytes. Our data indicate that, in analogy to other S-100-like proteins, MRP8 and MRP14 play a role in Ca(2+)-dependent cytoskeletal-membrane interactions. Restriction of MRP8/MRP14 expression to distinct stages of myelomonocytic differentiation suggests that these proteins are involved in highly specific pathways of intracellular signaling in phagocytes.  相似文献   
40.
In child and youth care in the Netherlands, systematic planning of treatment is more and more considered to be a condition for effective and well founded treatment. Although workers are convinced of the benefits of treatment plans, treatment planning is not yet a natural and integrated part of residential care. There are several pressure points. In this article a model of treatment planning will be presented that contributes to an answer to these pressure points. The theoretical bases and the practical implications of this model will be discussed.  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