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   1816篇
  免费   110篇
  国内免费   6篇
耳鼻咽喉   6篇
儿科学   30篇
妇产科学   30篇
基础医学   244篇
口腔科学   15篇
临床医学   184篇
内科学   320篇
皮肤病学   54篇
神经病学   157篇
特种医学   86篇
外国民族医学   2篇
外科学   358篇
综合类   13篇
预防医学   160篇
眼科学   11篇
药学   130篇
中国医学   1篇
肿瘤学   131篇
  2021年   33篇
  2020年   14篇
  2019年   23篇
  2018年   36篇
  2017年   16篇
  2016年   34篇
  2015年   19篇
  2014年   43篇
  2013年   85篇
  2012年   109篇
  2011年   109篇
  2010年   50篇
  2009年   52篇
  2008年   88篇
  2007年   79篇
  2006年   103篇
  2005年   91篇
  2004年   106篇
  2003年   72篇
  2002年   100篇
  2001年   65篇
  2000年   61篇
  1999年   56篇
  1998年   28篇
  1997年   12篇
  1996年   10篇
  1995年   17篇
  1994年   11篇
  1993年   8篇
  1992年   26篇
  1991年   27篇
  1990年   24篇
  1989年   20篇
  1988年   18篇
  1987年   31篇
  1986年   31篇
  1985年   21篇
  1984年   19篇
  1983年   11篇
  1982年   10篇
  1980年   7篇
  1979年   10篇
  1978年   15篇
  1977年   11篇
  1976年   9篇
  1975年   22篇
  1974年   14篇
  1973年   18篇
  1972年   7篇
  1971年   10篇
排序方式: 共有1932条查询结果,搜索用时 15 毫秒
31.
A century of publications on leishmaniasis in Alpes-Maritimes, in southern France, is here reviewed. Autochtonous human and canine leishmaniasis were first recognised in this département, which lies by the Mediterranean Sea and near the Italian border, in 1918 and 1925, respectively. The parasite responsible for the leishmaniasis, Leishmania infantum, is transmitted by Phlebotomus perniciosus and P. ariasi. The human leishmaniasis is zoonotic, with domestic dogs acting as the main 'reservoir' hosts. In prospective surveys over the last two decades, a mean of 12% of the domestic dogs checked in Alpes-Maritimes have been found seropositive for L. infantum but only about 50% of the seropositive animals showed any clinical signs of infection at the time of the surveys. During the last 30 years, 178 cases of human visceral leishmaniasis have been recorded in the area. Such cases are sporadic and often opportunistic, occurring predominantly in children (29% of the 178 cases) or HIV-positive subjects (31%). Recently, it has been demonstrated that, in Alpes-Maritimes, approximately 20% of those found seropositive in leishmanin skin tests are asymptomatic carriers, with amastigotes in their peripheral blood.  相似文献   
32.
Factors influencing hematopoietic recovery (HR) after autologous blood stem cell transplantation (ABSCT) were analyzed in 73 patients with various non-myeloid malignancies (NMM), and in 58 patients with acute myeloblastic leukemia (AML). Peripheral blood stem cells were collected following mobilization with chemotherapy, granulocyte colony-stimulating factor (G-CSF), or chemotherapy plus G-CSF. The conditioning regimen used consisted of either chemotherapy alone (112 cases) or chemotherapy plus total body irradiation (19 cases). The median number of colony-forming units granulocyte-macrophage (CFU-GM) was similar in both groups of patients, with the median number of CD34(+) cells infused being higher in the AML group (5.4 vs 4 x 10(6)/kg; P = 0.03). Median time neutrophils >0.5 x 10(9)/l was 13 days in both groups, and median time to a platelet count >20 x 10(9)/l was longer in AML patients (14 vs 12 days; P = 0.01). In multivariate analysis, the only factors affecting neutrophil recovery in the NMM group were the CD34+ cell number (continuous model) and the CFU-GM dose (categorized model) infused, whereas for platelet recovery, previous chemotherapy also remained significant. In the AML group, the only factors significantly affecting the speed of neutrophil recovery were dose of CD34+ cells administered and the patient's age. As for platelet recovery, only the progenitor dose administered remained significant. In the NMM group, the most discriminating cut-off values for a rapid neutrophil and platelet recovery were 1.5 x 10(6) and 2.5 x 10(6) CD34+ cells/kg, respectively, and for AML patients these figures were 1.5 x 10(6) and 4 x 10(6) CD34+ cells/kg, respectively. Our results confirm the slower HR after ABSCT in AML, and highlight the importance of progenitor cell dose in accelerating HR after ABSCT.  相似文献   
33.
BACKGROUND: To evaluate the contamination of delivery systems after an aerosol therapy session in patients with cystic fibrosis who have chronic Pseudomonas aeruginosa infection. METHODS: Fifty-three patients with cystic fibrosis were enrolled in the study from March 1996 to June 1997. All patients were age 7 years or older and had P aeruginosa infection. They also had been treated with recombinant deoxyribonuclease and were capable of producing sputum for culture. RESULTS: Nine devices were excluded for the study. A total of 44 nebulizers were included: 37 from patients with P aeruginosa colonization with a count of 10(6) colony-forming units/mL or more and 7 with a count of between 10(5) colony-forming units/mL and 10(6) colony-forming units/mL. CONCLUSION: This study demonstrates that in the absence of cleaning, nebulizers of patients with cystic fibrosis who are infected with P aeruginosa are likely to be contaminated by a pathogenic flora.  相似文献   
34.
35.
Chondrodysplasia punctata (CDP) is an etiologically heterogeneous disorder characterized by the radiographic finding of stippled epiphyses (punctate calcifications). It is often accompanied by a characteristic facial appearance, known as the Binder phenotype, which is attributed to hypoplasia of the nasal cartilages; abnormal distal phalanges (brachytelephalangy) are a common component manifestation as well. We report eight patients with a Binder phenotype with or without CDP who all shared a known or suspected maternal deficiency of vitamin K. We suspect that this phenotype is probably under recognized, and we hope to increase awareness about the maternal risk factors, especially hyperemesis gravidarum, which lead to nutritional deficiency. © 2013 Wiley Periodicals, Inc.  相似文献   
36.
Chondroitin sulfate and glucosamine sulfate exert beneficial effects on the metabolism of in vitro models of cells derived from synovial joints: chondrocytes, synoviocytes and cells from subchondral bone, all of which are involved in osteoarthritis (OA). They increase type II collagen and proteoglycan synthesis in human articular chondrocytes and are able to reduce the production of some pro-inflammatory mediators and proteases, to reduce the cellular death process, and improve the anabolic/catabolic balance of the extracellular cartilage matrix (ECM). Clinical trials have reported a beneficial effect of chondroitin sulfate and glucosamine sulfate on pain and function. The structure-modifying effects of these compounds have been reported and analyzed in recent meta-analyses. The results for knee OA demonstrate a small but significant reduction in the rate of joint space narrowing. Chondroitin sulfate and glucosamine sulphate are recommended by several guidelines from international societies for the management of knee and hip OA, while others do not recommend these products or recommend only under condition. This comprehensive review clarifies the role of these compounds in the therapeutic arsenal for patients with knee OA.  相似文献   
37.
Functional connectivity studies conducted at the group level using magnetoencephalography (MEG) suggest that resting state networks (RSNs) emerge from the large-scale envelope correlation structure within spontaneous oscillatory brain activity. However, little is known about the consistency of MEG RSNs at the individual level. This paper investigates the inter- and intra-subject variability of three MEG RSNs (sensorimotor, auditory and visual) using seed-based source space envelope correlation analysis applied to 5 min of resting state MEG data acquired from a 306-channel whole-scalp neuromagnetometer (Elekta Oy, Helsinki, Finland) and source projected with minimum norm estimation. The main finding is that these three MEG RSNs exhibit substantial variability at the single-subject level across and within individuals, which depends on the RSN type, but can be reduced after averaging over subjects or sessions. Over- and under-estimations of true RSNs variability are respectively obtained using template seeds, which are potentially mislocated due to inter-subject variations, and a seed optimization method minimizing variability. In particular, bounds on the minimal number of subjects or sessions required to obtain highly consistent between- or within-subject averages of MEG RSNs are derived. Furthermore, MEG RSN topography positively correlates with their mean connectivity at the inter-subject level. These results indicate that MEG RSNs associated with primary cortices can be robustly extracted from seed-based envelope correlation and adequate averaging. MEG thus appears to be a valid technique to compare RSNs across subjects or conditions, at least when using the current methods.  相似文献   
38.
Detection and estimation of the degree of chronic aortic insufficiency with pulsed Doppler echocardiography was attempted in 27 patients documented to have aortic insufficiency on aortography. Twenty-five patients had associated aortic stenosis or mitral valve disease, or both. A disturbed diastolic flow within the left ventricular outflow tract was recorded in all but one patient (Doppler sensitivity 96 percent). Aortic insufficiency was clinically undetected In three patients (clinical sensitivity 89 percent). In a small number of patients Doppler echocardiography also appeared to be highly specific for this disorder. The Doppler technique estimated the degree of aortic Insufficiency by assessing the distribution of diastolic flow within the outflow tract and the body of the left ventricle. A significant correlation between the Doppler method and the angiographic estimation of aortic insufficiency was found (r = 0.88, p < 0.01).  相似文献   
39.
This review emphasises the particular difficulties encountered in confirming a suspected case of cutaneous or visceral leishmaniasis when that case is co-infected with HIV. HIV infection appears to have a more profound impact on the development of visceral leishmaniasis than on the evolution of the purely cutaneous disease. The various techniques available for immunological, parasitological and molecular diagnosis are presented and evaluated. The value of serodiagnosis for the detection of antileishmanial antibodies is in part dependent on the antigens used. Western blots may have a use not only in diagnosis but also in predicting the cases of HIV infection that are at most risk of developing symptomatic leishmaniasis. The presence of leishmanial parasites may still only be demonstrated incontrovertibly by the microscopical examination of smears or the culture of blood or biopsy samples. The use of cultures not only permits diagnosis but also detailed study of the parasites. The potential use of PCR in diagnosis is explored and related to other possible tests. A recommended, standardized procedure for the diagnosis of leishmaniasis in HIV-infected patients is presented.  相似文献   
40.
The purpose of this study was (1) to characterize more fully the effects of phorbol esters to stimulate GnRH release in vitro and (2) to determine whether cocaine (which disrupts estrous cyclicity in rats) affected phorbol ester stimulation of GnRH release in vitro. Hypothalami were collected from ovariectomized rats injected subcutaneously with 50 micrograms/kg of 17 beta-estradiol benzoate the two previous mornings. Sagittal sections of this block of CNS tissue comprising the preoptic area/anterior hypothalamus and mediobasal hypothalamus/median eminence were perfused at a rate of 6.2 ml/h with a modified Krebs-Ringer buffer (pH 7.4) using a programmable perfusion system. Perfusion results showed that 10-min pulses of phorbol 12-myristate 13-acetate or phorbol 12,13-dibutyrate (PDBu) increased GnRH release in dose-dependent fashion (10(-10) to 10(-6) M) but had no effect on aminergic transmitter release. The biologically inactive alpha-phorbol was without effect on GnRH release. PDBu-stimulated GnRH release was blocked by both tetrodotoxin and cocaine, known inhibitors of Na+ influx. These results suggest a role for protein kinase C in regulating the release of GnRH. Our results that cocaine and tetrodotoxin attenuated phorbol ester stimulation of GnRH, presumably through inhibition of Na+ influx, suggest a direct biochemical mechanism for cocaine disruption of hypothalamic GnRH secretion and, consequently, cyclic reproductive function.  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