全文获取类型
收费全文 | 8677篇 |
免费 | 73篇 |
国内免费 | 5篇 |
专业分类
耳鼻咽喉 | 275篇 |
儿科学 | 5篇 |
妇产科学 | 148篇 |
基础医学 | 1030篇 |
口腔科学 | 260篇 |
临床医学 | 1660篇 |
内科学 | 906篇 |
皮肤病学 | 10篇 |
神经病学 | 140篇 |
特种医学 | 404篇 |
外科学 | 2103篇 |
综合类 | 7篇 |
预防医学 | 624篇 |
眼科学 | 155篇 |
药学 | 335篇 |
肿瘤学 | 693篇 |
出版年
2023年 | 6篇 |
2022年 | 11篇 |
2021年 | 18篇 |
2020年 | 13篇 |
2019年 | 7篇 |
2018年 | 22篇 |
2017年 | 18篇 |
2016年 | 24篇 |
2015年 | 38篇 |
2014年 | 65篇 |
2013年 | 62篇 |
2012年 | 332篇 |
2011年 | 684篇 |
2010年 | 344篇 |
2009年 | 50篇 |
2008年 | 483篇 |
2007年 | 683篇 |
2006年 | 693篇 |
2005年 | 686篇 |
2004年 | 803篇 |
2003年 | 807篇 |
2002年 | 869篇 |
2001年 | 547篇 |
2000年 | 736篇 |
1999年 | 373篇 |
1998年 | 116篇 |
1997年 | 6篇 |
1995年 | 7篇 |
1994年 | 8篇 |
1993年 | 28篇 |
1992年 | 11篇 |
1991年 | 23篇 |
1990年 | 18篇 |
1989年 | 15篇 |
1988年 | 13篇 |
1987年 | 16篇 |
1986年 | 7篇 |
1985年 | 7篇 |
1983年 | 9篇 |
1982年 | 7篇 |
1979年 | 8篇 |
1978年 | 10篇 |
1977年 | 12篇 |
1976年 | 7篇 |
1974年 | 9篇 |
1973年 | 5篇 |
1972年 | 4篇 |
1971年 | 4篇 |
1968年 | 4篇 |
1967年 | 4篇 |
排序方式: 共有8755条查询结果,搜索用时 15 毫秒
1.
Restriction maps of the rDNA cistron of twelve species of mosquitoes in six genera of the subfamily Culicinae were constructed using eight 6 bp recognition restriction enzymes. Anopheles albimanus was used as an outgroup. The size of the rDNA cistron ranged from 8.5 kb in Aedes katherinensis to 12.9 kb in Ae. polynesiensis. A total of twenty-six sites were scored; eighteen were polymorphic among ingroup taxa. The proportion of polymorphic nucleotide sites (Pnuc) was 0.059 and the heterozygosity per nucleotide site (Hnuc) was 0.028. Wagner and Fitch Parsimony, Dollo Parsimony and Nei-Li distance/neighbour-joining methods were used to construct phylogenetic trees. The rDNA RFLP dataset did not provide a well-supported phylogeny among culicine taxa. The RFLP phylogenies are incongruent with the morphology character based and molecular phylogenies and derived relationships did not correspond with current taxonomic classifications. The lack of resolution was due to homoplasy arising from frequent independent loss or gain of restriction sites among unrelated taxa. 相似文献
2.
V T Ivashkin Iu V Grigor'ev A I Sinopal'nikov N V Korneev D N Levitski? E A KazakovaIGVirs 《Kardiologiia》1991,31(8):59-61
The clinical effects of Tenoric, a long-acting combined drug (atenolol and chlorthalidone in a tablet), were studied in 31 patients with Stages I and II hypertensive disease, by using echocardiography, daily automatic blood pressure monitoring, bicycle ergometry, measurements of plasma renin and aldosterone. The drug was found to be highly clinically effective in labile and sustained hypertension. When given once or twice a day, it makes it possible to reliably monitor blood pressure, improve hemodynamic parameters, as reflected by lower cardiac output and decreased peripheral vascular resistance, reduce the estimated mass of the left myocardium, alleviate a pressor response to exercise and enhance its tolerance, lower plasma renin levels. The side effects of the drug are minimal and include moderate bradycardia. Peripheral vasospasm and systemic weakness were observed in single cases. There were no atherogenic changes in lipid spectrum and disturbed glucose and uric acid metabolism during the drug therapy. 相似文献
3.
4.
Sokolova IN Savelov NA Chistiakova OV Sorokin KV Gurariĭ LL Shatinina NN 《Arkhiv patologii》2005,67(6):38-43
59 angiomyolipomas were studied: immunohistochemistry (IHC) was used in 24 cases, electron microscopy (EM) in 6 cases. 57 tumors had a typical structure, 2 did not contain fat component. Premelanosomes were found by EM in one tumor. Smooth muscle actin was found in all tumor cells. Involvement of lymph nodes was observed in 2 patients. Histogenesis of this tumor is discussed. 相似文献
5.
The aim of this work, that was carried out using Wistar rats, was to characterize the response of neurons of different morphofunctional types to amphetamine administration and to study the possibility of correction of these changes by delta-sleep inducing peptide (DSIP). Single intraperitoneal injection of 60 microg/kg of DSIP following a long term amphetamine administration (2.5 mg/kg for 3 weeks) was shown to result in normalization of brain metabolism, that was disturbed by the drug. The correcting DSIP effect was found in rat brain structures judging by the parameters of the state of proteins in neurons of sensomotor cortex and caudate nucleus and by the activity of enzymes of neurotransmitter metabolism, such as type A and B monoamine oxidases and acetylcholine esterase, that was determined in subfractions of the same brain structures. DSIP modulating effect in phenamine stereotypy supports its role as an adaptogen of intercenter relations in CNS pathology. 相似文献
6.
Morphology of microparticles of the microencapsulated measles vaccine was studied by cryofractography, transmission electronic microscopy and by atomic force microscopy; co-polymers of polyacrylic acid and of sodium-alginate (spermidine) complexes were used as the matrix. The different-composition microcapsules had clear-cut borders and a certain range of sizes; but they were different in morphology, and their structures and densities varied identically with regard for a medium acidity, which is apparently preconditioned by some conformation-type alterations of matrix molecules. The studied preparations can, probably, protect the viral material in the stomach aggressive medium and release the material to ensure its contact with the intestine lymph tissue; thereof, they can be referred to as promising for further study of mucosal vaccines. 相似文献
7.
Shchelkanov MIu Kolobukhina LV Moskvina TM Aushev ID Kartoev AA Kelli EI Merkulova LN Grenkova EP Samokhvalov EI Petriaev VG Serobian AG Klimova EA Galkina IV Malyshev NA Aristova VA Slavskiĭ AA Luk'ianova NA Deriabin PG Gromashevskiĭ VL Efremenko VI Onishchenko GG L'vov DK 《Voprosy virusologii》2005,50(5):9-15
The laboratory verified cases of Crimean-Congo hemorrhagic fever (CCHF) in the piedmont steppes of the North Caucasus (Malgobeksky District, Republic of Ingushetia) are first described. The source of the first infection was Ixodidae ticks; three subsequent sources were contacts with the bloody discharges from patients. CCHF virus genome was detected in the blood of the cattle from an epidemic focus and in the pools of the Ixodes ticks Haemaphysalis parva Neum., 1897 and Boophilus annulatus Say, 1821, taken from cattle. The problem of including the piedmont steppes of the North Caucasus into the CCHF nosological area is discussed. 相似文献
8.
9.
10.
The aim of this chronic experimental study performed in 16 dogs was to determine the effect of epidural infusion of 0.01% clopheline solution on the morphological and histoenzymological characteristics of spinal ganglion neurons. Daily infusions of clopheline at the dose of 15 mg/kg for 14 days caused a decrease in capillary permeability in the spinal ganglia at the injection site and its increase in the intact areas. This finding suggests the changes in the activity of the microcirculatory bed with a disturbed interaction in capillary-neuron system. Analysis of morphometric parameters has demonstrated the presence of some functional and reversible dystrophic changes in spinal ganglion neurons, which were associated with epidural infusion of both clopheline and isotonic solution of sodium chloride. Determination of the activity of oxidation-reduction enzymes, which reflect the course of aerobic and anaerobic processes in spinal ganglion neurons, has shown no significant differences between the groups of animals infused with or isotonic solution of sodium chloride. In conditions of chronic experiment no significant variations were found in RNA content in ganglionic cells at and outside the sites of infusion of clopheline and of isotonic solution of sodium chloride. 相似文献