全文获取类型
收费全文 | 50913篇 |
免费 | 3031篇 |
国内免费 | 247篇 |
专业分类
耳鼻咽喉 | 630篇 |
儿科学 | 1177篇 |
妇产科学 | 1217篇 |
基础医学 | 7076篇 |
口腔科学 | 1500篇 |
临床医学 | 5574篇 |
内科学 | 11004篇 |
皮肤病学 | 799篇 |
神经病学 | 5014篇 |
特种医学 | 1762篇 |
外科学 | 6311篇 |
综合类 | 325篇 |
一般理论 | 44篇 |
预防医学 | 3616篇 |
眼科学 | 805篇 |
药学 | 3446篇 |
1篇 | |
中国医学 | 59篇 |
肿瘤学 | 3831篇 |
出版年
2023年 | 321篇 |
2022年 | 632篇 |
2021年 | 1145篇 |
2020年 | 748篇 |
2019年 | 981篇 |
2018年 | 1198篇 |
2017年 | 1069篇 |
2016年 | 1258篇 |
2015年 | 1315篇 |
2014年 | 1743篇 |
2013年 | 2509篇 |
2012年 | 3797篇 |
2011年 | 3986篇 |
2010年 | 2368篇 |
2009年 | 2156篇 |
2008年 | 3289篇 |
2007年 | 3595篇 |
2006年 | 3205篇 |
2005年 | 3262篇 |
2004年 | 3002篇 |
2003年 | 2798篇 |
2002年 | 2569篇 |
2001年 | 426篇 |
2000年 | 351篇 |
1999年 | 482篇 |
1998年 | 561篇 |
1997年 | 459篇 |
1996年 | 407篇 |
1995年 | 346篇 |
1994年 | 305篇 |
1993年 | 308篇 |
1992年 | 237篇 |
1991年 | 230篇 |
1990年 | 210篇 |
1989年 | 220篇 |
1988年 | 196篇 |
1987年 | 173篇 |
1986年 | 178篇 |
1985年 | 210篇 |
1984年 | 181篇 |
1983年 | 166篇 |
1982年 | 192篇 |
1981年 | 159篇 |
1980年 | 139篇 |
1979年 | 112篇 |
1978年 | 122篇 |
1977年 | 131篇 |
1976年 | 94篇 |
1975年 | 107篇 |
1974年 | 81篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
Petra M.C. Callenbach Lise P.M. Pels Paul G.H. Mulder Wim H.J.P. Linssen Rob H.J.M. Gooskens Jan L. van der Zwan Oebele F. Brouwer For the SUM Trial Group 《European journal of paediatric neurology》2007,11(6):325-330
About 4-10% of children and adolescents suffer from migraine. In the last few years, several studies have been performed to assess the efficacy and safety of triptans for the acute treatment of migraine in children and adolescents. Only sumatriptan nasal spray has been approved for the treatment of acute migraine with or without aura in adolescents aged 12-17 years in Europe. This review describes the results of the studies with sumatriptan nasal spray that have been performed in children and adolescents, including a study performed in the Netherlands. 相似文献
82.
A paleopathological maxilla and mandible with tooth agenesis were analyzed, focussing on the aetiology of the condition. The jaw material, derived from an adult mediaeval male, was examined by standard anthropological analyses, including radiography. In the maxilla there was agenesis of three permanent incisors and one premolar, and in the mandible of one permanent incisor and two permanent molars. Absence or marked reduction of the incisive foramen and the nasopalatine canal was found. The pattern of tooth agenesis was similar to the pattern observed in contemporary individuals, except for the agenesis of one permanent maxillary centreal insisor. It is suggested that the pronounced lack of the premaxillary area of the nasopalatine canals and the incisive foramen. As the condition can be ascribed to deviations in the prenatal developments, this investigation shows that embryological developmental patterns, which form the basis for the pattern of tooth agenesis, should be taken into account when evaluation dry bonde patholgy. 相似文献
83.
Ryohei Kuwatsuru David M. Shames Andreas Mühler Jan Mintorovitch Vladimir Vexler Jeffry S. Mann Frederic Cohn David Price John Huberty Robert C. Brasch M.D. 《Magnetic resonance in medicine》1993,30(1):76-81
Magnetic resonance imaging enhanced with a macromolecular contrast medium (MMCM), albumin-Gd-DTPA, was used to estimate the plasma volume in vivo in the myocardium, lung, liver, and skeletal muscle of 10 normal rats. The plasma volumes of the same tissues in a parallel group of six rats were estimated in vitro by a conventional radioisotopic technique (111In-transferrin). Plasma volumes of myocardium, lung, liver, and skeletal muscle estimated by the MR technique (μl plas. ia cc-1 of tissue) were 101,109,163, and 11.0, respectively, while plasma volumes measured by the In-transferrin radioisotope technique (mg plasma g-1 of tissue) were 78.6, 215,143, and 11-2, respectively. Assuming a ratio of densities of aerated lung to blood of 0.45 and of other tissues to blood of 1.0, correlation between the methods was excellent (R2 = 0.99) indicating that MR imaging enhanced with MMCM permits reliable in vivo estimation of tissue plasma volume in the rat. 相似文献
84.
Pleural mesotheliomas and asbestos exposure in the pulp and paper industries: a new risk group identified by linkage of official registers 总被引:4,自引:0,他引:4
Bengt Jrvholm Hans Malker Birgitta Malker Jan Ericsson Gerd Sllsten 《American journal of industrial medicine》1988,13(5):561-567
Analysis of data obtained by linking the 1960 Swedish Census and the Swedish Cancer Registry has demonstrated an increased risk of pleural mesothelioma among pulp and paper workers. The present study was undertaken with the aim of revealing possible environmental risk factors. The work histories of the 25 cases identified earlier were reviewed. "Certain" or "probable" exposure to asbestos was found among 70% of these workers. The study illustrates how linkage of official registers can be used to identify new risk environments and encourage the establishment of preventive measures. 相似文献
85.
David de Wied Jan M. van Ree 《European archives of psychiatry and clinical neuroscience》1989,238(5-6):323-331
Summary Animal studies have demonstrated that neuropeptides modulate nervous system functions. It has been postulated that disturbances in neuropeptide systems may be aetiological factors in psychiatric and neurological disorders. Neuropeptides related to ACTH/MSH, including ORG 2766, increase motivation and attention and facilitate recovery processes after nerve damage. These peptides may be effective during the early stage of dementia. Vasopressin and related peptides improve memory processes in animals and humans. In addition, these peptides influence social behaviour, mood and addictive behaviour. The non-opioid -type endorphins have neurolepticlike activities in animals and antipsychotic effects in a category of schizophrenic patients. Peptides related to CCK have also been found to be effective in these patients. Some neuropeptides, e.g. TRH and PLG, have been reported to exert antidepressant effects. Further research may eventually produce neuropeptides with therapeutic action in psychiatric and neurological diseases.Parts of this article were presented on the occasion of the inauguration ceremony of the Department of Psychiatry of the University of Mainz on April 2 and 3, 1987 相似文献
86.
Gert Jan Laarman Menco G. Niemeyer Albert V. G. Bruschke Fred J. Verzijlbergen T. Liam Go Ernst E. van der Wall Carl A. P. L. Ascoop 《European journal of nuclear medicine and molecular imaging》1989,15(5):239-243
To establish test specific normal limits for quantitative analysis of uptake and washout of 201Tl after dipyridamole infusion combined with low level exercise, 20 healthy volunteers were studied with low likelihood of coronary artery disease (CAD) assessed by a stepwise probability analysis based on age, sex, symptoms, resting electrocardiogram, and exercise electrocardiography. Likelihood of CAD in these volunteers was calculated as 1%. After dipyridamole infusion combined with low level exercise, one volunteer complained of headache; no other side effects were observed. There were no chest pain complaints. Maximal hemodynamic changes were achieved during the 6th and 7th min of the test. No ST segment depression was recorded. Visual analysis of the 201Tl scintigrams was normal in all volunteers. Mean regional washout at 4 h was 44.37%±2.11%. The regional washout in the 70° LAO view (46.65%±1.10%) was significantly higher than in the anterior and 30° LAO views (43.44%±1.50% and 43.02%±1.45%, respectively). Profiles of uptake and washout of 201Tl were different after dipyridamole infusion combined with low level exercise as compared to maximal exercise. Thus, in quantitative analysis of 201Tl scintigraphy after dipyridamole infusion in conjunction with low level exercise as applied in the present study, it is mandatory to use normal limits of uptake and washout of 201Tl derived from healthy volunteers who underwent the same combined protocol. 相似文献
87.
Mario Feola Jan Simoni David Fishman Rue Tran Peter C. Canizaro 《Artificial organs》1989,13(3):209-215
Hemoglobin (Hb) solutions can cause vasoconstriction and activation of intravascular coagulation. Because the endothelium plays a major role in the regulation of vascular tone and hemostasis, a study was conducted of human umbilical vein endothelial cells (EC) incubated with various Hbs. Cell injury was evaluated by electron microscopy and the release of lactic dehydrogenase, H2O2, and procoagulant "tissue factor." Cell reaction was assessed by the measurement of 6-keto-prostaglandin F (PGF)1 alpha (metabolite of prostacyclin) and thromboxane B2 (metabolite of thromboxane A2). Incubation with unmodified bovine hemoglobin for 24 h caused no cell injury and a reaction characterized by 48.4 +/- 8.2% increase in 6-keto-PGF1 alpha production, accompanied by 40.2 +/- 9.4% reduction in thromboxane (Tx)B2 (compared with a control group of EC incubated with saline solution). Incubation with a nonpure Hb solution (Hb plus red blood cell membrane aminophospholipids; a-PLs) caused cell injury with significant release of tissue factor, plus a reaction characterized by 97.5 +/- 12.5% increase in TxB2 production accompanied by 25.3 +/- 3% reduction in 6-keto-PGF1 alpha. A second nonpure Hb [Hb plus bacterial environmental endotoxin (E)] caused cell injury, the release of tissue factor, and increased production of both prostaglandins, with greater release of TxB2 (197 +/- 17%) than of 6-keto-PGF1 alpha (112 +/- 8.3%). These data indicate that the endothelium reacts differently to pure and nonpure hemoglobins. The biocompatibility of Hb solutions, with regard to vasoconstriction and activation of intravascular coagulation, depends on the absence of stromal a-PLs and bacterial E. 相似文献
88.
89.
The Susan Britton Wills Unit at the Bristol General Hospital is a small and busy multidisciplinary psychiatric unit, providing a wide range of in-patient, out-patient and day-patient services for the residents of Bristol Health District.
Full text
Full text is available as a scanned copy of the original print version. Get a printable copy (PDF file) of the complete article (1.6M), or click on a page image below to browse page by page.
1314 相似文献90.
Interactions of rutaecarpine alkaloids with specific binding sites for 2,3,7,8-tetrachlorodibenzo-p-dioxin in rat liver 总被引:1,自引:0,他引:1
Gillner Mikael; Bergman Jan; Cambillau Christian; Gustafsson Jan-Ake 《Carcinogenesis》1989,10(4):651-654
Rutaecarpine alkaloids have the capacity to inhibit specific2,3,7,8-[1,6-3H]tetrachlorodibenzo-p-dioxin (TCDD) binding inrat liver cytosol, as analysed by electrofocusing in polyacrylamidegel. The IC50 value for binding of 7,8-dehydrorutaecarpine wasestimated to 7 nM indicating a high-affinity interaction, whereasrutaecarpine appeared less active (IC50 110 nM). These findingsare of interest in view of the fact that analogues to thesecompounds may be formed following UV-irradiation of tryptophanand that such photo-products have been suggested to constitute(the) endogenous ligand(s) for the TCDD receptor. As furthersupport of this notion, the rutaecarpine alkaloids investigatedcould be fitted into a rectangle of 6.8x13.7 A, a characteristiccommon for most high affinity ligands of the TCDD receptor hithertostudied. In view of their structural similarity to dehydrorutaecarpineand the agreement of their mol. wt with that of the photoproductwith the highest affinity for the TCDD receptor, we suggestdeaza-analogues of dehydrorutaecarpine to represent possiblecandidates for the endogenous TCDD receptor ligand. 相似文献