全文获取类型
收费全文 | 2384920篇 |
免费 | 172560篇 |
国内免费 | 4405篇 |
专业分类
耳鼻咽喉 | 35291篇 |
儿科学 | 77530篇 |
妇产科学 | 67331篇 |
基础医学 | 336024篇 |
口腔科学 | 67832篇 |
临床医学 | 205457篇 |
内科学 | 469854篇 |
皮肤病学 | 53094篇 |
神经病学 | 188327篇 |
特种医学 | 95419篇 |
外国民族医学 | 1056篇 |
外科学 | 368192篇 |
综合类 | 53797篇 |
现状与发展 | 7篇 |
一般理论 | 766篇 |
预防医学 | 172645篇 |
眼科学 | 55202篇 |
药学 | 178750篇 |
6篇 | |
中国医学 | 5008篇 |
肿瘤学 | 130297篇 |
出版年
2018年 | 22712篇 |
2016年 | 19390篇 |
2015年 | 21959篇 |
2014年 | 30736篇 |
2013年 | 46948篇 |
2012年 | 63279篇 |
2011年 | 67030篇 |
2010年 | 40019篇 |
2009年 | 38422篇 |
2008年 | 64183篇 |
2007年 | 69509篇 |
2006年 | 69972篇 |
2005年 | 68034篇 |
2004年 | 66535篇 |
2003年 | 64444篇 |
2002年 | 63379篇 |
2001年 | 113974篇 |
2000年 | 117777篇 |
1999年 | 99946篇 |
1998年 | 26993篇 |
1997年 | 24435篇 |
1996年 | 24282篇 |
1995年 | 22997篇 |
1994年 | 21622篇 |
1993年 | 20176篇 |
1992年 | 78370篇 |
1991年 | 76337篇 |
1990年 | 74519篇 |
1989年 | 72041篇 |
1988年 | 66799篇 |
1987年 | 65806篇 |
1986年 | 62199篇 |
1985年 | 59281篇 |
1984年 | 44469篇 |
1983年 | 37625篇 |
1982年 | 22177篇 |
1981年 | 20194篇 |
1979年 | 41397篇 |
1978年 | 29130篇 |
1977年 | 25044篇 |
1976年 | 23014篇 |
1975年 | 25691篇 |
1974年 | 30240篇 |
1973年 | 29242篇 |
1972年 | 27636篇 |
1971年 | 25503篇 |
1970年 | 24151篇 |
1969年 | 22745篇 |
1968年 | 21085篇 |
1967年 | 18923篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
941.
Kindling is a process in which episodic electrical stimulation permanently increases seizure susceptibility. One mechanism to account for a change in seizure susceptibility is some alteration in signal transduction, possibly at the level of second messenger systems. In this study, male Long-Evans rats were kindled in the amygdala, and Ca2+/calmodulin (Ca2+/CaM)-dependent protein phosphorylation was assessed at the site of the primary kindled focus using one- and two-dimensional gel electrophoresis. In vitro phosphorylation of membrane and cytosol fractions in the presence of absence of Ca2+/CaM did not differentiate kindled from nonkindled amygdaloid tissue. These results suggest that changes in Ca2+/CaM-dependent phosphorylation are not related to the mechanism(s) underlying the establishment of an amygdaloid kindled focus. 相似文献
942.
M Battaglia M Gasperini G Sciuto P Scherillo G Diaferia L Bellodi 《Schizophrenia bulletin》1991,17(4):659-668
In a study of the families of 21 schizotypal patients, we found an increased morbidity risk for schizophrenia compared with that in the families of 21 nonschizotypal patients and 42 controls. The Axis I diagnoses did not influence the distribution of the morbidity risk in the families of the schizotypal patients. If the schizotypal subjects also had other personality disorders, the morbidity risk for schizophrenia among their relatives was lower, although not significantly. 相似文献
943.
The clinical features and prognosis of pseudoseizures diagnosed using video-EEG telemetry 总被引:25,自引:0,他引:25
A total of 110 patients underwent diagnostic evaluation for attacks of uncertain origin by means of video-EEG telemetry and had a diagnosis of pseudoseizures confirmed. Eighty-six patients (78%) were female, mean age of onset 25 years, and mean duration of attacks was 3 years. Many of the patients had erroneously been thought to be suffering from epilepsy. The attacks could be divided into two broad categories: attacks of collapse (one-third) and attacks with prominent motor activity (two-thirds). In some patients, the attacks were associated with incontinence and injury. The differential diagnosis and clinical features of the attacks are described. Additional psychiatric features were present in 52 (47%) patients. Follow-up (for a median 5 years; range, 1 to 14 years) showed that 40% of these patients stopped having pseudoseizures. This favorable outcome was associated with being female, leading an independent life, a formal psychological approach to therapy and counseling, and the absence of coexisting epilepsy, but not with the duration of pseudoepilepsy, prior episodes of pseudostatus, the coexistence of overt psychiatric disease, or the clinical features of the attacks. 相似文献
944.
This report deals with the control of detrusor hyperreflexia by the intravesical instillation of oxybutynin hydrochloride (OH) in 10 male and 3 female patients with complete suprasacral spinal cord lesions having clean intermittent catheterisation (CIC) because of unbalanced voiding. The indication for intravesical OH application was persisting urinary incontinence despite CIC in 11 patients and in 2 patients detrusor hypercontractility. One 5 mg tablet of OH was dissolved in distilled water and the solution was instilled into the bladder through the catheter, which has been used for urodynamics and which was then removed. Six hours later cystometry was repeated and the clinical effects were studied especially with regard to continence/incontinence and side-effects. The differences in the cystometric bladder capacity and maximum detrusor pressure before and after instillation of OH are statistically highly significant. Clinically, from those 10 patients who were incontinent between CIC before, 9 remained dry during the 6-hour period. None of the patients reported any side-effect after intravesical application of OH. However, with subsequent oral medication 8 out of 12 patients complained of typical anticholinergic side-effects. These results indicate that treatment with topical OH is an effective alternative to treating detrusor hyperreflexia, especially in patients already on CIC because of unbalanced voiding, but with persisting urinary incontinence due to detrusor hyperreflexia. OH is well absorbed from the bladder, however absorption seems to be protracted compared to oral intake. 相似文献
945.
The possibility that exposure to powerline frequency (60-Hz) magnetic fields might affect the form or intensity of epileptic seizures, induced by administration of pentylenetetrazol (PTZ) in rats, was examined. Male adult rats were exposed to either 60-Hz magnetic fields with intensities of up to 1.85 gauss (185 microT) or to a sham field condition, for 1 h prior to injections of PTZ (45-75 mg/kg). The subsequent seizures were monitored and recorded on videotape and any subsequent mortalities were noted. Exposure to 60-Hz magnetic fields prior to administration of PTZ was found to significantly (P less than 0.005) reduce the lethality of the drug-induced seizures. The LD50 for the sham-exposed group was 65.88 mg/kg, whereas for the 60-Hz magnetic field-exposed rats, the LD50 was 85.33 mg/kg. In some experiments exposure to the 1.0 and 1.5 gauss magnetic fields also produced significant (P less than 0.05) reductions in seizure durations. These findings suggest that acute exposure to low intensity 60-Hz magnetic fields has an inhibitory effect on the lethality and expression of PTZ-induced seizures in rats. Some possible mechanisms, which could account for these observed effects of magnetic field exposure on seizures, are discussed. 相似文献
946.
Zusammenfassung Die Osteotomie des Oberkiefers in der Le-Fort-I-Ebene, die heute routinemäßig in der Down-fracture-Technik durchgeführt wird, hat die chirurgische Behandlung skelettaler Dysgnathien grundlegend verändert. Sie ermöglicht eine dreidimensionale Korrektur des Oberkiefers und damit des gesamten Gesichtsschädels. Darüber hinaus kann der Oberkieferzahnbogen, zusätzlich zu einer Verlagerung des gesamten Oberkiefers, durch eine zusätzliche sagittale und transversale Osteotomie erweitert, verschmälert und verkürzt werden. Die Planung einer Oberkieferosteotomie erfolgt anhand des klinischen Bildes, der Kiefermodelle und des Fernröntgenbildes. Dabei muß der Unterkiefer frühzeitig mit in die Planung einbezogen werden, da er durch die Autorotation im Gelenk den Verlagerungen des Oberkiefers folgt. Erst durch eine gleichzeitige Osteotomie auch des Unterkiefers ergibt sich ein weites Indikationsspektrum für die Oberkieferosteotomie. Bei einer kombinierten Ober- und Unterkieferosteotomie ist praktisch jedes gewünschte Profil im unteren Gesichtsdrittel erzielbar.
Summary The osteotomy of the maxilla using the Le Fort I technique, today routinely performed in the down-fracture-technique, has changed surgical corrections of dentofacial deformities fundamentally. It offers a three-dimensional correction of the maxilla and also of the whole facial skull. Furthermore the upper dental arch can be expanded, intruded and shortened using a sagittal or transversal osteotomy in addition to a complete transposition of the maxilla. Planning of a maxillary osteotomy is performed under consideration of the clinical situation, the casts and the lateral cephalogram. The mandible must be considered at an early state of the preoperative planning, since the mandible will follow all transpositions of the maxilla by rotating with the TMJ. Only by performing a simultaneous osteotomy of the mandible, a broad spectrum of indications for maxillary osteotomy will result and practically every desired profile of the lower third of the face can be achieved using combined maxillary and mandibular osteotomies.相似文献
947.
948.
Glass ionomer restorative cement offers the clinician an alternative to bonded composite resin for restoration of certain lesions in primary teeth. This article details a step-by-step procedure for restoration of a smooth surface carious lesion in a primary incisor using an encapsulated glass ionomer restorative material and reviews advantages and limitations of the cement. A light-hardened glass ionomer liner/base that has proven useful as an enamel and dentin restorative is also described. 相似文献
949.
To produce hybrids, one member of the parental line is genetically made male-sterile. This male-sterile trait is encoded by mitochondria so that it is maternally inherited. Consequently, the progeny of a male-sterile plant is fully sterile. Nevertheless, during the handling of cytoplasmic male-sterile seed stocks, some mixture with seeds of the maintainer lines can occur. Up to the present time, the only way to check the homogeneity of the cytoplasmic male-sterile seed stock was to grow the plants until flowering time. We have developed a method which can be used immediately after the harvest, allowing us to check samples from both sunflower and sugar beet. We used the mitochondrial plasmid, present only in the maintainer lines, as a probe for the total nucleic acids prepared from the cytoplasmic male-sterile seed stocks which might be contaminated. The signals compared to those of samples artificially contaminated allow us to measure as few as one male-fertile seed in 1000 seeds in a rapid and accurate manner. 相似文献
950.
N-Hydroxythalidomide (1d), a potential metabolite of thalidomide (1a), was synthesized from N-phthalyglutaminic acid anhydride (1b) and O-tetrahydropyraline hydroxylamine, followed by deprotection. The teratogenicity of 1d was studied using the Hen's-Egg-Test model which had been found applicable for 1a. 1d was more teratogenic to chicken embryos compared to 1a. The percentage of teratogenic malformations in the 1d groups was 28-46%, whereas the percentage in the 1a groups was 20-23%. The oxygen protected precursor N-hydroxythalidomide (1c) was less teratogenic (11-15%). 相似文献